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Andrews’ Chapter 20 pgs 526-547. JoAnne M. LaRow, D.O. December 9, 2003. Phylum Protozoa. One-celled organisms Divided into classes according to nature of locomotion Class Sarcodina move by temporary projections of cytoplasm (pseudopods) Class Mastigophora by means of one or more flagella

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andrews chapter 20 pgs 526 547

Andrews’ Chapter 20pgs 526-547

JoAnne M. LaRow, D.O.

December 9, 2003

phylum protozoa
Phylum Protozoa
  • One-celled organisms
  • Divided into classes according to nature of locomotion
  • Class Sarcodina move by temporary projections of cytoplasm (pseudopods)
  • Class Mastigophora by means of one or more flagella
  • Class Ciliata by short, hair-like projections of cytoplasm (cilia)
  • Class Sporozoa with no special organs of locomotion
class sarcondina
Class Sarcondina
  • Best known organism in class: ameba
  • Entamoeba histolytica is ameba of medical significance
  • Amebiasis cutis begins as deep abscesses that rupture
  • These form ulcerations with distinct, raised, cordlike edges and an erythematous halo approx. 20 cm wide
  • Base is covered with necrotic tissue and hemopurulent, glairy, pus-containing amebae
Multiple large ulcers
  • Extensive tissue destruction
  • Resembles pyoderma gangrenosum
amebiasis cutis
Amebiasis Cutis
  • Lesions may occur on trunk, abdomen, external genitalia, buttocks, or perineum
  • Abdominal lesions may arise from hepatic abscesses
  • All ages are at risk
  • Intestinal amebiasis, with bloody diarrhea and hepatic abscesses, may be present
  • Chronic urticaria may be sole manifestation of early amebiasis
  • Organism may be found at base of lesion by direct smear or shave bx
histology amebiasis
  • Necrotic ulceration with many lymphocytes, neutrophils, plasma cells, and eosinophils
  • E. histolytica is found in tissue, within blood and lymph vessels
  • Organisms measures 50-60 microns in diameter
  • Has a basophilic cytoplasm, a single eccentric nucleus with a central karyosome
diagnosis amebiasis
Diagnosis Amebiasis
  • Organism is frequently demonstrable in fresh material from base of ulcer
  • Indirect hemagglutination test results remain elevated for yrs after initial invasive disease onset
  • Whereas, results of gel diffusion precipitation tests and counterimmunoelectrophoresis become neg at 6 months
  • This property can be used to test for recurrent or active disease in persons coming from endemic areas
tx amebiasis
  • Recommended is Metronidazole 750 mg orally TID for 10 days, followed by iodoquinol 652 mg TID for 20 days
  • Surgical drainage for abscesses
class mastigophora
Class Mastigophora
  • Organisms are known as flagellates
  • Many have undulating membrane with flagella along crest
  • Trichomonas vulvovaginitis is a common cause of vaginal pruritis with burning and frothy leukorrhea
  • Vaginal mucosa appears bright red from inflammation and may be mottled with pseudomebranous patches
  • Males may harbor organism and develop urethritis and prostatitis, and occasionally balanoposthitis
  • Neonates may acquire infection during passage through birth canal, but require tx only if symptomatic or if colonization lasts more than 4 weeks
  • However, as this is otherwise nearly exclusively a sexually transmitted disorder, trichomonas vulvovaginitis in a child should make one suspect sexual abuse
  • Tx Metronidazole 2.0 g in single oral dose TOC
  • Alternatively, 500 mg twice daily for 7 days may be given
  • Warn pts not to drink alcohol for 24 hrs after last dose because disulfiram type of effects of this med
  • Male sex partners should be tx
  • Metronidazole is contraindicated in pregnant women-use clotrimazole intravaginally
Colorless pyriform flagellate 5-15 microns long
  • Demonstrated in smears from affected areas
  • DIF is sensitive and specific
  • Three forms:
  • A.) cutaneous form restricted to skin
  • B.) mucocutaneous form affects both skin and mucosal surfaces
  • C.) visceral leishmaniasis that affects organs of reticulo-endothelial system
  • Cutaneous leishmaniasis, American mucocutaneous leishmaniasis, and visceral leishmaniasis (kala-azar), which includes infantile leishmaniasis and post-kala-azar dermal leishmaniasis, are all caused by morphologically and culturally indistinguishable protozoa of the family Trypanosomidae, called Leishmania
cutaneous leishmaniasis
Cutaneous Leishmaniasis
  • Several types of lesions
  • All tend to occur on exposed parts as all are transmitted by the sandfly
  • Organisms are obligate intracellular parasites existing in two forms: promastigote and amastigote
  • In gut organisms multiply as extracellular flagellated promastigotes
  • Following migration to the proboscis, parasites are inoculated (in promastigote form) via sandfly bite
  • These transform into amastigotes within cells of the reticuloendothial system in host- be it human, rodent or canine
old world leishmaniasis
Old World Leishmaniasis
  • Limited to the skin
  • Called Baghdad boil, oriental sore, leishmaniasis tropica, birskra button, Delhi boil, Aleppo boil, Kandahar sore, & Lahore sore
  • May present in two ways: moist or rural type, a slow growing, indurated, livid, indolent papule which enlarges in a few months to form an ulcer as much as 5 cm in diameter
  • Spontaneous healing takes place within 6 months, leaving a characteristic scar
  • Contracted from rodent reservoirs such as gerbils via the sand fly as vector
  • Short incubation period-1-4 weeks
old world leishmaniasis23
Old World Leishmaniasis
  • Dry or urban type
  • Has a longer incubation period (2-8 months or longer)
  • Develops more slowly, and heals more slowly than the rural type
leishmaniasis recidivans
Leishmaniasis Recidivans
  • Rarely, after initial or “mother “ lesion heals, there may appear at the borders of healed areas a few soft red papules covered with scales and having the “apple jelly” characteristics of lupus vulgaris
  • These spread peripherally on an erythematous base and are called lupoid type
  • Aka leishmaniasis recidivans
  • Occurs most commonly with urban type caused by L. tropica
new world leishmaniasis
New World Leishmaniasis
  • Subtypes present of purely cutaneous involvement are uta, pain bois, and bay sore or chiclero ulcer
  • Primary papule may become nodular, verrucous, furuncular, or ulcerated, with an infiltrated red border
  • Subcutaneous peripheral nodules, which eventually ulcerate, may signal extension of disease
  • A sporotrichoid pattern may occur with lymphadenopathy, and nodes may rarely yield organisms
  • Recidivans lesions are unusual in New World form of disease
American cutaneous leishmaniasis
  • Lesion of localized cutaneous leishmaniasis presenting as an indurated nodule with an ulcerated crateriform center
Cutaneous leishmaniasis
  • A well circumscribed ulcerated lesion on the face of a child
Cutaneous leishmaniasis
  • Multiple ulcerated lesions on the legs of a rural worker
Circular scars at previous sites of cutaneous leishmaniasis
  • Often only sign of a previous infection
chiclero ulcer
Chiclero Ulcer
  • In Yucatan and Guatemala, a subtype of New World disease exists: the chiclero ulcer
  • Most frequently site of infection is the ear
  • Lesions ulcerate and occur most frequently in workers who harvest chicle for chewing gum in the forests, where there is high humidity
  • This form is a more chronic ulcer that may persist for yrs, destroying ear cartilage and leading to deformity
  • Etiologic agent is L. mexicana and the vector, a sandfly, Lutzomyia flaviscutellatta
  • Uta is a term used by Peruvians for leishmaniasis occurring in mountainous territory at elevations of 1200 to 1800 meters above seas level
  • Ulcerating lesions are found on exposed sites, and mucosal lesions do not occur
disseminated cutaneous leishmaniasis
Disseminated Cutaneous Leishmaniasis
  • May be seen in New and Old World disease
  • Multiple nonulcerated papules and plaques
  • Chiefly on exposed surfaces
  • Caused by several subspecies of L. mexicana
  • L. aethiopica be etiology in Ethiopia and Kenya
  • Begins with a single ulcer, nodule, or plaque
  • Satellite lesions may develop & cover entire body
  • Disease is progressive and tx ineffective
  • Characterized by anergy to organism
  • Montenegro rxn is negative
  • Cutaneous leishmaniasis is endemic in Asia Minor & to a lesser extent in many countries around the Mediterranean Sea
  • Iran and Saudi Arabia have a high occurrence rate
  • Purely cutaneous lesions are found in Central and South America & 9 pts who acquired their disease in Texas have been reported
  • Children are affected most often, since immunity is acquired from initial infection
  • Deliberate inoculation on thigh is sometimes practiced so that scarring on face- a frequent site for Oriental sore-may be avoided
  • Organism has an alternate life in vertebrate and an insect host
  • Man and other mammals such as dogs and rodents are the natural reservoir hosts
  • Host vectors are Phlebotomus sandflies in Old World type and Phlebotomus perniciosus & Lutzomyia sandflies for the New World cutaneous leishmaniasis
  • After insect has fed on blood, the flagellates (leptomonas, promastigote) develop in gut in 8-20 days, after which migration occurs into the mouth parts; from here transmission into humans occurs by a bite
  • In humans, flagella are lost and a leishmanial form (amastigote) is assumed
  • Typical features of an ulcer: heavy infiltrate of histiocytes, lymphocytes, and a polymorphonuclear leukocytes
  • Numerous organisms are present ( mostly in histiocytes), which are nonencapsulated and contain a nucleus and a paranucleus
  • Wright’s, Giemsa, and monoclonal antibody staining may be helpful in identifying the organisms
  • Parasitized histiocytes form tuberculoid granulomas in dermis
  • Pseudoepitheliomatous hyperplasia may occur in edges of ulcer
Localized cutaneous leishmaniasis: a diffuse infiltrate extends into the subcutis
  • Epidermis is ulcerated
Mixed cell infiltrate with many plasma cells and neutrophils but with histiocytes predominating
  • Organisms are seen within the histocytes
diagnosis cont d
Diagnosis (cont’d)
  • More sophisticated tests to diagnose and classify subspecies involve detection of monoclonal antibodies with immunoperoxidase, radiolabeling, or fluorescenation, DNA probes, DNA buoyancy, restriction-endonuclease fragment patterns of kenetoplast DNA, restriction-frequent length polymorphisms of unclear DNA, and isoenzyme electrophoresis
montenegro skin test
Montenegro skin test
  • Uses leishmanial antigen to induce a cell-mediated response
  • Can be used as a diagnostic method
  • Cannot distinguish between past & present infections
  • Skin tests can be false-neg in anergic pts with disseminated infections
  • Demonstration of organism in smears
  • Parasites can be cultured from tissue fluid
  • A hypodermic needle is inserted into normal skin and to edge of ulcer base
  • Needle is rotated to work loose some material and serum, which is then aspirated
  • Culture on Nicolle-Novy-MacNeal (NNN) medium at 22 degrees- 35 degrees C
  • Leishmanin intradermal test may be helpful in nonendemic areas (Leishman-Montenegro-Donovan)
  • It becomes positive 3 months after infection
  • Spontaneous healing occurs, usually within 12-18 months, shorter for Old World disease
  • Rationale for tx an ordinarily self-limited infection include avoiding disfiguring scars in exposed areas, avoiding secondary infection; controlling disease in the population; and failure of spontaneous healing; in diffuse cutaneous and recidivans types, disease may persist for 20-40 yrs if untreated
tx cont d
Tx (cont’d)
  • In areas which localized cutaneous leishmaniasis is not complicated by recidive or sporotrichoid forms or mucocutaneous disease, tx with topicals: Paromycin sulfate 15% plus methylbenzethonium chloride 12%
  • Ketoconazole cream under occlusion,
  • Cryotherapy, local heat, and laser ablation, or with intralesional sodium stibogluconate antimony or emetine hydrochloride, may be effective and safe
  • Perilesional injections of interferon-gamma have also been reported to be effective but are expensive
tx cont d46
Tx (cont’d)
  • In pts who are immunocompromised or who acquire disease in areas where mucocutaneous disease may occur, systemic therapy is recommended
  • Many alternatives reported effective
  • Sodium antimony gluconate (sodium stibogluconate) solution given IV or IM-20mg/kg/day in two divided doses for 28 days
  • Repeated courses may be given
  • Antimony n-methyl glutamine (Glucantime) is used more often in Central and South America because of its local availability
  • Ketaconazole (600mg/day for 28 days), itraconazole, dapsone, rifampin, and allopurinol
tx cont d47
Tx (cont’d)
  • Some of these have not been subjected to control trials, as is true of most topical treatments
  • Recidive and disseminated cutaneous types may require prolonged courses or adjuvant interferon therapy
  • Amphotericin B may be used in antimony-resistant disease
  • Control depends on success of anti-fly measures taken by health authorities
mucocutaneous leishmaniasis leishmaniasis americana espundia
Mucocutaneous Leishmaniasis (Leishmaniasis Americana, Espundia)
  • Infection occurs at site of fly bite
  • Initially a destructive ulcer
  • Secondary lesions on the mucosa occur at the same time or sometime during the next 5 yrs
  • Earliest mucosal lesion is hyperemia of nasal septum with subsequent ulceration
  • Ulceration progresses to invade septum and later paranasal fossae
  • Perforation of septum eventually takes place
  • Nose remains unchanged externally, despite internal destruction
clinical features
Clinical Features
  • Initially only dry crust is observed, or a bright red infiltration or vegetation on nasal septum
  • Symptoms are obstruction and small hemorrhages
  • Despite mutilation and destruction it never involves nasal bones
  • When septum is destroyed, nasal bridge and tip of nose collapse, giving an appearance of a parrot beak, camel nose, or tapir nose
  • Four of the great chronic infections (syphilis, tuberculosis, leprosy, and leishmaniasis) have a predilection for the nose
  • Ulcer may extend to lips and continue to advance to pharynx, attacking soft palate, uvula, tonsils, gingiva, tongue
Eventual mutilation is called espundia
  • Two perpendicular grooves at union of osseous palate and soft tissues, in mist of vegetative infiltration of the entire pharynx is called the palate cross of espundia
  • Only in exceptional cases does American leishmaniasis invade genital or ocular mucous membranes
  • Frequency of mucous membrane involvement is variable
  • In Yucatan and Guatemala it is an exception
  • In other countries such as Brazil, it may occur in 80% of cases
  • Mucocutaneous leishmaniasis is predominantly a rural and jungle disease
  • It predominates in damp and forested regions
  • Can be contracted at any time of the year-risk is highest just after the rainy season
  • Affects all ages and races and both sexes are equally affected
  • In cases of granulomatous infiltration, when intracellular parasites are found in histiocytes, leishmaniasis is one of several disease to consider
  • Others are: rhinoscleroma, histoplasmosis, granuloma inginale, and toxoplasmosis
  • Leishman-Donovan body is nonencapsulated and shows a characteristic nucleus and parabasal body
  • Touch smears stained with Giemsa are helpful in may cases of cutaneous and mucocutaneous leishmaniasis
lab findings
Lab Findings
  • Leishmania is demonstrated in cutaneous and mucous membrane lesions by direct smears or cultures
  • Bx stained with Wright’s stain intracellular and extracellular organisms with typical morphology or two chromatic structures: nucleus & parabasal body
  • In later mucosal lesions there are less parasites making ID difficult
  • Cx via NNN medium is useful
  • Intradermal Montenegro test is performed
  • A suspension of 0.1-0.2 ml injected intradermally
lab findings55
Lab Findings
  • A reading is made 48-72 hrs later
  • Positive rxn is an area of induration greater than 5 mm in diameter 24-48 hrs after injection
  • Test is specific and sensitive, 95% positive results
  • But can be neg in early cases of disease
  • But it is easy to find the parasites
  • Cross rxn’s occur with certain forms of TB, but are rare
treatment mucocutaneous
  • Same as described for cutaneous leishmaniasis except that antimony resistance is common
  • Combination therapy using antimonials with other drugs like rifampin
  • Or adding immunomodualtors such as interferon gamma or interleukin-2 may result in cure
  • Amphotericin B tx may be needed
visceral leishmaniasis kala azar dumdum fever
Visceral Leishmaniasis (Kala-Azar,Dumdum Fever)
  • Earliest lesion is cutaneous nodule or leishmanioma
  • Occurs at site of initial sandfly inoculation
  • Kala-azar means “black fever”
  • Acquired its name because of patchy macular darkening of skin caused by deposits of melanin these develop later on in disease
  • Patches are most marked over forehead and temples, periorally, and on midabdomen
Nodules of various sizes
  • Some pedunculated
  • Pt has been tx for kala-azar over 6 month period over 20 yrs ago
visceral leishmaiasis
Visceral Leishmaiasis
  • Primary target for parasite is reticuloendothelial system; spleen, liver, bone marrow, and lymph nodes
  • Incubation period: 1-4 months
  • And intermittent fever,temps ranging from 39 degrees- 40 degrees ushers in the disease
  • Hepatosplenomegaly, agranulocytosis, anemia thrombocytopenia
  • Chills, fever, emaciation, wt loss, weakness, epistaxis, and purpura develop
  • Susceptibility to secondary infection may produce pulmonary and GI infection, ulcerations in the mouth (crancrum oris), and noma
  • Death occurs in 2 yrs if untreated
  • L. donovani spp. Donovani, infantum, & chagasi
  • These are parasite of rodents, canines, and humans
  • They are nonflagellate oval organisms 3 microns in diameter, known as Leishman-Donovan bodies
  • In the sandfly it is a leptomonad form with flagella
  • Leishman-Donovan bodies may be present in individuals with kala-azar of India
  • Specimens for examination in descending order of utility: spleen pulp, sternal marrow, liver tissue, and exudate from lymph nodes
  • Culture on NNN medium may also reveal organisms
  • The intradermal Montenegro test is also reliable
  • For tx: general support measures; pentavalent antimony is drug of choice
post kala azar dermal leishmanoid
Post-Kala-Azar Dermal Leishmanoid
  • In kala-azar leishmanoid forms (amastigote) may be widely distributed throughout apparently normal skin
  • During & after recovery a special form of dermal leishmaniasis known as post-kala-azar dermal leishmanoid appears
  • Condition appears during or shortly after tx in African form
  • Appearance may be delayed up to 10 yrs after tx in Indian form
  • It is common in India, occurring in up to 20% of pts; in Africa only 2% develop it
post kala azar dermal leishmanoid68
Post-Kala-Azar Dermal Leishmanoid
  • Two constituents of eruption: a macular, de-pigmented eruption found mainly on face, arms, and upper part of trunk; a warty, papular eruption in which amastigotes can be found
  • Pts may act as a chronic reservoir of infection-it may persist for up to 20 yrs
  • Condition closely resembles leprosy
  • Evidence that pts who will develop this have a marker interleukin-10 in their keratinocytes and sweat glands
vicerotropic leishmaniasis
Vicerotropic Leishmaniasis
  • 1 report of 8 soldiers developing systemic infection with L. tropica while fighting in Operation Desert Storm in Saudi Arabia
  • None had symptoms of kala-azar, but 7 had fever, fatique, malaise, cough, diarrhea, or abdominal pain
  • 1 pt was aymptomatic
  • None had cutaneous disease
  • In 7 diagnostic tests were pos. via bone marrow aspiration and 1 via lymph node aspiration
  • 5 of 6 tx’d with sodium stibogluconate improved
human trypanosomiasis
Human Trypanosomiasis
  • Three species are pathogenic to humans: Trypanosoma gambiense and T. rhodesiense in Africa; T. cruzi in America
  • Early stages of African trypanosomiasis a chancre may occur at site of tsetse fly bite
  • Next erythema with circumscribed swellings of angioedema, enlargement of lymph glands, fever, malaise, headache, and joint pain occurs
  • In West African (Gambian) form, illness is chronic over yrs with progressive deterioration
  • In East African (Rhodesian) form illness is acute with a stormy, fatal course of weeks to months
chagas disease
Chagas’ disease
  • Reduviid bug (kissing bug, assassin bug) usually bites at night, frequently at mucocutaneous junctions, where bug’s infected feces are deposited when it feeds
american trypanosomiasis
American Trypanosomiasis
  • Unsuspecting sleeping person rubs the feces into the bite and becomes infected
  • If bite occurs around the eye Romana’s sign develops; this consists of unilateral conjunctivitis and edema of eyelids, with an ulceration or chagoma in area
  • Bite becomes markedly swollen and red whether trypanosomes are involved or not
  • Acute Chagas’ disease is usually mild with fever, malaise, edema of face and lower extremities and generalized lymphadenopathy
chagas disease76
Chagas’ Disease
  • Prevalent in Central and South America from the U.S. to Argentina and Chile; highest incidence is Venezuela, Brazil, Uruguay, Paraguay, and Argentina
  • Approx. 29% of all male deaths in 29-44 yr age group in Brazil are ascribed to Chagas’ disease
tx chagas disease
Tx: Chagas’ Disease
  • Before CNS involvement occurs, suramin, a complex, non-metal-containing, organic compound, is tx of choice
  • For American trypanosomiasis, tx is of limited efficacy
  • Nifurtimox and benzimidazole clear the parasitemia and reduce severity of acute illness
  • There is a high incidence of adverse effects
  • Conservative tx is most appropriate for pt with CHF from Chagas’ myocarditis
  • GI complications(megaesophagus & megacolon) may be tx’ed surgically
chronic chagas
Chronic Chagas’
  • Occurs in 10-30% of infected persons yrs to decades later
  • Heart (myocarditis, arrhythmias, thromboembolism, and cardiac failure) & GI (megaesophagus and megacolon)
  • In the remaining infected but asymptomatic phase pts may pass the disease through transfusion
african trypanosomiasis
African Trypanosomiasis
  • In West Africa due to Trypanosoma brucei gambiense infection
  • In East Africa caused by Trypanosoma brucei rhodesiense infection
  • Vectors are usually several species of tsetse flies
  • Cutaneous manifestations include a localized bite rxn (‘trypanosomal chancre’) & an annular eruption coinciding with fever spike
rhodesian trypanosomiasis
Rhodesian Trypanosomiasis
  • Endemic among cattle-raising tribes of East Africa
  • With savannah habitat of the vectors determining its geographic distribution
  • Wild game and livestock are reservoir hosts as well as humans
  • The tsetse fly Glossina morsitans is the principal vector
gambian trypanosomiasis
Gambian Trypanosomiasis
  • Humans are the only vertebrate host and the palpalis group of tsetse flies is the invertebrate host
  • These flies are found close to water
  • Their fastidious biologic requirements restrict their distribution & distribution of disease
  • Incidence is seasonal, with humidity and temperature being determining factors
  • Highest incidence is in males 20-40 yrs old in tropics of West and Central Africa
Bite rxn earliest lesion
  • Called trypanosomal chancre
  • Resembles a boil but is painless
  • Aspirated fluid contains actively dividing trypanosomes
class sporozoa



  • A zoonosis caused by a parasite protozoan
  • Called Toxoplasma gondii
  • Manifestations vary (mild-severe);infection may be congenital or acquired
  • Congenital infection occurs from placental transmission-abortion or stillborn may result
  • Congenital toxoplasmosis presents with triad of hydrocephalus, chorioretinitis, and cerebral calcification
  • In addition there may be hepatosplenomegaly and jaundice
  • Skin changes are rare and nonspecific
congenital toxoplasmosis
Congenital Toxoplasmosis
  • Macular and hemorrrhagic eruptions predominate
  • Blueberry muffin lesions, reflect dermatoerythropoesis may occur
  • Abnormal hair growth and exfoliative dermatitis may also occur
acquired toxo
Acquired Toxo
  • Cutaneous and subcutaneous nodules, macular, papular, and hemorrhagic eruptions, followed by scarlatiniform desquamation, roseola-like, erythema multiforme-like, and lichen planus-like eruptions as well as exfoliative dermatitis
  • Eruption is usually accompanied by high fever and general malaise
acquried toxo
Acquried Toxo
  • Diagnosis of acquired toxo is important to:
  • healthy pregnant women concerned about recent exposure
  • adults with lymphadenopathy, fever, and myalgia, acute or chronic, who might have other serious diseases, such as lymphoma;
  • immunocompromised persons: such pts with AIDS, in whom toxoplasmosis might be fatal
  • it is the most common cause of focal encephalitis in pts with AIDS
acquired toxo91
Acquired Toxo
  • 20% of pregnant women have already had the disease and are protected
  • They are identified by a positive test very early in pregnancy, or just before pregnancy
  • A high titer just before the twentieth week of gestation might be an indication for tx or such a test before delivery-tx of infant
  • Immunofluorescence or complement fixation tests may be helpful
  • Diagnosis in adults is made by rising or high antibody test
  • Characteristic histologic changes in lymph nodes may be confirmatory
  • In congenital cases and rarely in acquired ones, chorioretinitis may occur a decade or more after infection
  • In congenital infection chorioretinitis is usually bilateral, whereas in acquired type it is usually unilateral
  • Toxoplasma gondii is a crescent-shaped, oval, or round protozoan
  • Can infect any mammalian or avian cell
  • Disease often is acquired through contact with animals-cats usually
  • Two major routes of transmission: oral and congenital
  • Meats used for human consumption may contain tissue cysts, therefore serving as a source of infection when eaten raw or undercooked
  • No evidence of human –to-human spread other than from mother to fetus
toxo diagnosis
  • Cannot be made clinically alone
  • Must isolate the organism
  • Protozoa can be found in tissue sections, smears, or body fluids by Wright’s or Giemsa stain; characteristic lymph node histology; serologically
  • Mouse inoculation with properly prepared tissue, ie lymph node, spinal fluid, or peripheral blood, may isolate and identify the parasite if stained with Giemsa or Wright’s stain
  • Antibodies are most commonly detected by Sabin-Feldman dye test, which becomes positive 10-14 days after initial infection
  • Maximum titer is attained in 4-5 weeks
  • Worldwide distribution, with several areas having a greater than 90% seropositivity
  • Occurs in eastern U.S. more frequently than in western U.S.
  • Resevoirs of infection reported have been dogs, cats, cattle, sheep, pigs, rabbits, rats, pigeons, and chickens
toxoplasmosis tx
  • Combination of pyrimethamine (Daraprim), and sulfadiazine act synergistically and form an effective tx
  • Dosages and total tx time vary according to age and immunologic competence of infected pt
  • Pyrimethamine is a folic acid antagonist, so concomitant folinic acid therapy is recommended
phylum cnidaria

Phylum Cnidaria




Sea anemones

All are radial marine animals

portugese man of war dermatitis
Portugese Man-of-War Dermatitis
  • Stings are characterized by linear lesions
  • Erythematous, urticaria, and even hemorrhagic
  • Common sites are forearms, sides of trunk, thighs, and feet
portuguese man of war dermatitis
Portuguese Man-of-War Dermatitis
  • Usual local manifestations are sharp, stinging, and intense pain
  • Internally there may be severe dyspnea, prostration, nausea, abdominal cramps, lacrimation, and muscular pains
  • Death may occur if areas stung are large in relation to size of pt
  • Fluid of nematocytes contain toxin that is carried into human victim through barbs along the tenticle
  • Venom is a neurotoxic poison that can produce marked cardiac changes
portugese man of war dermatits
Portugese Man –of-War Dermatits
  • Each Portuguese man-of-war is a colony of symbiotic organisms consisting of a blue to red float or pneumatophore with a gas gland
  • Several gastrozooids measuring 1-20 mm, reproductive polps, and fishing tentacles bearing the nematocytes from which barbs are ejected
  • Hydroid is found mostly along southeastern Florida coastline and in Gulf of Mexico, and on windward coasts throughout the mid-Pacific and South Pacific
jellyfish dermatitis
Jellyfish Dermatitis
  • Produces similar lesions of man-of-war, except not as linear
  • Delayed and persistent lesions were described by Reed et al from stings incurred in the Aegean and Caribbean areas
  • Prolonged hypersensitivy reactions have been reported associated with specific antijellyfish immunoglobulins
The most dangerous of all is Chironex fleckeri, the Australian sea wasp
  • It is colorless and transparent
  • Its sting is often fatal
  • Another seas wasp Carybdea marsupialis, is much less dangerous and occurs in Caribbean
seabather s eruption
Seabather’s eruption
  • An acute dermatitis beginning a few hrs after bathing in the ocean
  • Erythematous macules and papules appear that may develop into pustules or vesicles
  • Urticarial plaques may be present less commonly
  • Crops of new lesions may occur for up to 72 hrs
  • Eruption persists for 10-14 days on average
  • It is quite pruritic
Seabather’s eruption occurs along the coast of the Atlantic Ocean and affects covered areas of body
  • Cnidatian larvae become entrapped under bathing suit and the nematocyst releases its toxin because of external pressure
  • Buttocks and waist are primarily affected, with breast also involved in women
  • It has been noted that seabathers who take off their suit and shower soon after leaving the water may limit the eruptions
hydroid sea anemone and coral dermatits
Hydroid, Sea Anemone, and Coral Dermatits
  • Pts contacting the small marine hydroid Halecium may develop a dermatitis
  • These organisms grows like a centimeter-thick coat of moss on submerged portions of vessels or pilings
  • Sea anemones produce reactions similar to those produced by jellyfish and hydroids
  • Coral cuts are injuries caused by exoskeleton of corals, Milleporina
  • Milleporina have a largely undeserved reputation for becoming inflamed and infected & for delayed healing
  • The combination of implantation of fragments of coral skeleton and infection (since cuts occur moat commonly on feet) probably accounts almost entirely for these symptoms
  • Detoxification as soon as possible after injury is advisable for all of these types of stings or cuts
tx of stings cuts
Tx of Stings & Cuts
  • All therapy is the same: fire corals, hydroids, jellyfish, sea anemone
  • Soak wound in 5% acetic acid (vinegar)
  • Leading alternative is isopropyl alcohol (40-70%)
  • Meat tenderizer has been reported to be effective but not as reliable as vinegar
  • Detoxicant should be applied continuously for at least 30 mins
tx continued
  • Next, any large visible tentacles should be removed with forceps in a double-gloved hand
  • Remaining nematocytes should be removed by applying a layer of shaving cream and shaving area gently
  • Fresh water and abrasion will worsen the envenomation
  • Topical anesthetics or steroids may be applied after decontamination
  • Systemic rxn’s may occur either through large amounts of venom or a previously sensitizing exposure from which anaphylaxis may result
  • Specific antivenin is available for the box-jellyfish
sponges and bristleworms
Sponges and Bristleworms
  • Sponges have horny spicules of silicon dioxide and calcium carbonate
  • Some sponges produce dermal irritants such as halitoxin and okadaic acid
  • Others may be colonized by cnidaria
  • Allergic or irritant rxn’s may result
  • Bristleworms may also produce stinging
  • All of these may be tx’d by first using adhesive tape to remove spicules, then applying vinegar soaks and then applying a topical steroid
sea urchin injuries
Sea Urchin Injuries
  • Puncture wounds inflicted by brittle, fragile spines of seas urchins, mainly genus Diadema or Echinothrix, are stained blue-black by the spines and may contain fragments of the spines
  • These are rarely large enough to require removal
  • Foreign-body or sarcoidlike granulomas may develop
  • Injuries from spines of genus Tripneustes have been reported to cause fatal envenomation-but this genus is not found on U.S. coasts
  • Envenomations may occur from stingrays, scorpionfish, stonefish, catfish, & weaverfish
  • These wounds should be immersed in nonscalding water (45 degrees C) for 30-90 mins or until pain subsides
  • Calcified fragments may be visible on x-ray evaluation, with fluoroscopy guiding extraction of spines, especially on hands and feet
  • Debridement and possibly antibiotic therapy for deep puncture wounds of hands and feet is recommended
  • There is a specific antivenin for stonefish stings
seaweed dermatitis
Seaweed Dermatitis
  • Caused by marine alga
  • Dermatitis occurs 3-8 hrs after individual emerges from ocean
  • Distribution is in parts covered by a bathing suit: scrotum, penis, perineum. And perianal area
  • Caused by marine plant-Lyngbya majuscula Gomont
  • Observed on in bathers off windward shore of Oahu, Hawaii
  • Prophylaxis refraining from swimming in waters turbid with such algae
  • Shower within 5 mins after swimming; active tx same as acute burns
dogger bank itch
Dogger Bank Itch
  • Eczematous dermatitis caused by sea chervil, Alcyondium hirsutum
  • A seaweed-like animal colony
  • These mosses or sea mats are found on the Dogger Bank, an immense shelflike elevation under the North Sea between Scotland and Denmark
phylum platyhelminthes

Phylum Platyhelminthes

Flatworms: two classes:

Trematodes &Cestodes

Cestodes: segmented, ribbon-shaped flatworms that inhabit intestinal tract as adults and involve subcutaneous tissue, heart, muscle, eye in larval form

Encased in a sac eventually becoming calcified

class trematoda
  • Schistosome cercarial dermatitis
  • Severely pruritic, widespread, papular dermatitis
  • Caused by cercariae of schistosomes for which humans are not hosts (usually waterfoal and rodents like muskrats)
  • Eggs in excreta of these animals are deposited in water then hatch into swimming miracidia
  • Miracidia enter a snail, where further development occurs
  • From snail, free-swimming cercariae emerge to invade human skin on accidental contact
schistosome cercarial dermatitis
Schistosome Cercarial Dermatitis
  • These swimming, colorless, multi-cellular organisms are less than a millimeter long
  • Exposure to cercariae occurs when swimming or more often wading in water containing them
  • They attack by burrowing into skin, where they die
  • Species that cause this eruption cannot enter the bloodstream or deeper tissue
  • After coming out of water a transient erythematous eruption appears
  • After a few hrs eruption subsides and pruritis too
  • After quiescent period of 10-25 hrs symptoms recur, erythematous macules & papules develop in exposed areas
After several days the dermatitis heals spontaneously
  • There are two types: freshwater swimmer’s itch & saltwater marine dermatitis or clam-digger’s itch
  • It is not communicable
  • Can be prevented by thoroughly washing and drying with a towel after exposure
visceral schistosomiasis bilharziasis
Visceral Schistosomiasis (Bilharziasis)
  • Cutaneous manifestations begin with mild itch and a papular dermatitis of feet and other parts after swimming in polluted streams containing cercariae
  • Types of schistosomes causing this can penetrate into bloodstream and eventually inhabit venous system draining the urinary bladder (Schistosoma haematobium) or intestines (S. mansoni or S. japonicum)
  • After an asymptomatic incubation period, there may be a sudden illness with fever and chills, pneumonitis, and eosinophilia; petechial hemorrhages may occur
cutaneous schistosomiasis
Cutaneous Schistosomiasis
  • Granulomas most frequently involve genitalia, perineum, and buttocks
  • These bilharziomas usually caused by eggs of S. haematobium or S. mansoni
  • Vegetating, soft, cauliflower-shaped masses occur
  • Fistulous tracts and extensive hard masses occur; these are riddled by sinuses exudating a seropurulent discharge with characteristic odor
  • Phagedenic ulcerations and pseudoelephantiasis of scrotum, penis, or labia may occur
cutaneous schistosmiasis
Cutaneous Schistosmiasis
  • Infrequently, ectopic or extra-genital lesions may occur mainly on trunk
  • This is a papular eruption tending to group in plaques and become darkly pigmented and scaly
katayama fever
Katayama Fever
  • Severe urticarial eruption
  • Aka urticarial fever
  • Frequently present along with a S. japonicum infection
  • Occurs at beginning of oviposition,4-8 weeks after infection
  • Occurs mainly in China, Japan, Philippines
  • Fever, malaise, abdominal cramps, arthritis, and liver and spleen involvement are seen
  • Felt to be a serum sickness-like rxn
katayama fever126
Katayama Fever
  • Prevention includes: reducing infection sources, preventing contamination by human excreta of snail-bearing waters, control of snail hosts, avoiding exposure to cercaria-infested waters
  • Prophylactic measures are still being sought after
  • Tx: praziquantel (Biltricide) 20 mg/kg orally for each of two treatments in 1 day= TOC
  • S. japonicum requires 3 doses in 1 day
  • Schistosomicides exhibit toxicity for host as well as for parasite
  • Risk of undesirable side effects may be enhanced by concomitant cardiac, renal, or hepatosplenic disease
cysticerosis cutis
Cysticerosis Cutis
  • Natural intermediate host of pork tape worm is the pig
  • But humans may act in this role
  • Tapeworm known as Taenia solium
  • Larval stage of T. solium is Cysticercus cellulosae
  • Infection takes place after ingestion of food contaminated with eggs or by reverse peristalsis of eggs or proglottides from intestines to stomach
  • Eggs hatch, freeing the oncospheres
  • Onchospheres enter general circulation and form cysts in various parts of body: striated muscle, brain, eye, heart, and lung
cysticercosis cutis
Cysticercosis Cutis
  • In subcutaneous tissues lesions are usually painless nodules containing cysticerci
  • These are more or less stationary, numerous and often calcified (therefore seen on x-ray)
  • Pain and ulceration may occur
  • Disease is most prevalent in countries where pigs feed on human feces
  • Ddx: gumma, lipoma, epithelioma
  • Positive dx is via incision and examination of interior of calcified tumor, where parasite will be found
cysticercosis cutis130
Cysticercosis Cutis
  • Tx: Praziquantel 10mg/kg of body wt=TOC for intestinal tapeworms
  • Five times this dose for 15 days is required if CNS is involved
  • This regimen has no effect on calcified parasites-these need to be surgically removed
  • Caused by larva of tapeworm of species Spirometra
  • Adult tapeworm lives in intestines of dogs and cats
  • Rare tissue infection
  • Occurs in two forms:
  • Application sparganosis-occurs when an ulcer or infected eye is poulticed with flesh of an infected intermediate host-larvae become encased in small nodules in the infected tissues
  • Ingestion sparganosis: occurs when humans ingest inadequately cooked meat, such as snake or frog, or when humans drink water contaminated with cyclops which are infected with plerocercoid larvae
  • 1-2 slightly pruritic or painful nodules may form in subcutaneous tissue or on the trunk and legs
  • Humans are the accidental intermediate host of the Sparganum which is the alternative name for the plerocercoid larva
  • Tx is surgical removal or ethanol injection of infected nodules
  • Also known as hydatid disease
  • In humans, infection is produced by ova reaching mouth by hands, in food, or from containers soiled by ova-contaminated feces from an infected dog
  • Leading to Echinococcus granulosus infestation of liver and lungs
  • Soft, fluctuating, semitranslucent, cystic tumors may occur in skin, sometimes in supraumbilical area as fistulas from underlying liver involvement
  • These tumors become fibrotic or calcified after the death of the larva
  • Eosinophilia or intractable urticaria and pruritus may be present
  • Tx: excision with care not to rupture the cyst
  • Albendazole combined with percutaneous drainage may also be used
  • Marine, freshwater, or terrestrial types
  • After attaching to skin, they secrete an anticoagulant, hirudin
  • They then engorge themselves with blood
  • Local symptoms at site of bite include: ulceration, bullae, hemorrhage, pruritus, whealing, necrosis
  • Allergic rxn’s including anaphylaxis may occur
  • They may be removed by applying salt, alcohol, or vinegar, or by use of a match flame
  • Bleeding may be stopped by direct pressure or by applying a styptic pencil to site
  • Medicinally leeches may be used to salvage tissue flaps threatened by venous congestion
class nematoda




Creeping Eruption


Larva Currens



  • Pinworm, seatworm, oxyuriasis
  • Main complaint is nocturnal pruritus ani
  • Seen most frequently in children
  • Vagina may become infested with gravid pinworms
  • Restlessness, insomnia, enuresis, irritability may be seen
  • Cause by roundworm Enterobius vermicularis
  • May infest small intestines, cecum, and large intestine of humans
  • Worms, especially gravid ones, migrate toward rectum and at night emerge to peri-anal and perineal areas to deposit thousands of ova
  • Worm then dies outside the intestines
  • These ova are carried back to mouth of host on the hands
  • Larvae hatch in duodenum and migrate into the jejunem and ileum where they reach maturity
  • Fertilization occurs in the cecum, thus completing the life cycle
  • Humans are only known host of pinworm
  • It is probably the widest distributed of all helminths
  • Infection occurs from hand-to-mouth transmission, often from handling soiled clothes, bedsheets, etc
  • Ova under the fingernails are a common source
  • Ova may be airborne and collect in dust on furniture and floors
  • Investigation may show that all members of the family of an affected person harbor the infection
  • It is common in orphanages and mental institutions and among people living in communal groups
  • Diagnosis is made by demonstration of ova in smears taken from anal region early in morning before defecation
  • With pt in knee-chest position, a smear is obtained from anus with a small eye curette
  • This is placed on a glass slide with a drop of saline solution
  • It is also possible to use Scotch tape, looping the tape sticky-side out over a tongue depressor and then pressing it several times against perianal region
  • Tape is then smoothed out on a glass slide
  • A drop of a solution containing iodine in xylol may be placed on the slide before the tape to aid in detection of ova
  • These tests should be repeated on 3 consecutive days to rule out infection
  • Ova may be detected under the fingernails of infected persons
  • It is also feasible to identify dead pinworms in the stool
  • Tx: Albendazole 400 mg or mebendazole 100 mg repeated in 2 weeks
  • Personal hygiene and cleanliness at home ar important
  • Cut fingernails short, and scrub frequently
  • Sheets, underwear, towels, pajamas, and other clothing should be laundered throughly and separately
hookworm disease
Hookworm Disease
  • AKA ground itch, uncinariasis, ancylostomiasis, necatoriasis
  • Earliest skin lesions are erythematous macules and papules, which become vesicles in a few hrs
  • These are itchy and occur on soles, toe webs, and ankles
  • Contents of vesicles become rapidly purulent
  • These lesions are produced by invasion of the skin by Ancylostoma or Nector larvae and precede the generalized symptoms of disease by 2-3 months
  • Cutaneous lesions last less than 2 weeks before larvae continue their human life cycle
  • Eosinophilia may rise to 40% around 5th day of infection
hookworm disease146
Hookworm Disease
  • Onset of constitutional symptoms is accompanied by progressive iron deficiency anemia and debility
  • Urticaria often occurs
  • Skin becomes dry and pale or yellowish
  • Hookworm is a specific communicable disease caused by Ancylostoma duodenale or Necator americanus
  • In soil they become infective larvae in 5-7 days
  • Tiny larvae (which can scarcely be seen with a small pocket lens), when they come into accidental contact with bare feet, penetrate skin and reach capillaries
hookworm disease147
Hookworm Disease
  • Larvae are carried in circulation to lungs-through capillary walls into bronchi-move up trachea to pharynx and being swallowed, eventually reach their habitat in the small intestine
  • Here they bury their heads in mucosa and begin their sexual life
hookworm disease148
Hookworm Disease
  • Prevalent in most tropical and subtropical countries and is often endemic in swampy and sandy localities in temperate zones
  • In temperate zones larvae are killed off each winter and soil is re-contaminated from humans the following summer
  • Nector americanus prevails in Western Hemisphere, Central and South Africa, South Asia, Australia, & Pacific islands
hookworm disease149
Hookworm Disease
  • Defecation habits of infected individuals in endemic areas is responsible for its widespread distribution
  • Also cause is human feces for fertilization in may parts of the world
  • The climate is such that people go barefoot due to heat
  • Finding the eggs establishes a diagnosis
  • Ova appear in feces 5 weeks after onset of infection
hookworm disease151
Hookworm Disease
  • Tx: expulsion of parasites from body and tx by preventing re-infection through proper disposal of human feces
  • Albendazole 100mg once or mebendazole 100 mg BID for 3 days is effective
  • Prophylaxis depends on preventing fecal contamination of soil
creeping eruption
Creeping Eruption
  • AKA larva migrans
  • Twisting, winding linear skin lesions produced by burrowing of larvae
  • Victims are people who go barefoot at beaches, children playing in sandboxes, carpenters and plumbers working under homes, and gardeners
  • Most common areas involved are feet, buttocks, genitals, and hands
  • Onset characterized by local itching and appearance of papules at sites of infection
larva migrans
Larva Migrans
  • Intermittent stinging pain occurs, and thin, red, tortuous lines are formed in skin
  • Migrations begin 4 days after inoculation and progress at a rate of 2 cm per day
  • Larvae may remain quiescent for several days or even months
  • Linear lesions are often interrupted by papules marking sites of resting larvae
larva migrans156
Larva Migrans
  • As eruption advances, old parts tend to fade, but sometimes there are purulent manifestations caused by secondary infection; erosions and excoriations caused by scratching may occur
  • If disease is not interrupted by tx larvae usually die in 2-8 weeks, with resolution of eruption
  • Rarely eruption has persisted for up to 1 yr
larva migrans158
Larva Migrans
  • Majority of cases in this country are caused by penetration by larvae of a cat and dog hookworm Ancylostoma braziliense
  • This is acquired from body contact with excreta of dogs and cats
  • This is common along coast of southwestern US
  • Tx: Ivermectin 150 micrograms/kg as a single 12-mg dose or albendazole 200 mg BID for 3 days
  • Criteria for successful tx are relief of symptoms and cessation of tract extension- usually occurs within a week
  • Topical thiabendazole 10% oral suspension QID will help with pruritus and tracts become inactive within 1 week
  • Characterized by migratory, intermittent, erythematous, urticarial plaques
  • Each episode of painless swelling lasts from 7-10 days and recurs every 2-6 weeks
  • Movement of underlying parasite may be as much as 1 cm/hr
  • Total duration of illness may be 10 yrs
  • Histopathologic exam of skin swelling will demonstrate eosinophilic panniculitis
  • Clinical manifestation has been called larva migrans profundus
  • Nematode Gnathostoma dolorosi or spingerum is cause
Most cases occur in Asia or South America

Eating raw flesh from second intermediate host, most commonly freshwater fish, in form of sashimi & ceviche allows humans to become definitive host

One report of eating raw snake flesh

As the larval cyst in the flesh is digested, larva becomes motile and penetrates gastric mucosa, usually within 24-48 hrs of ingestion

Symptoms then occur as migration of parasite continues

Surgical removal is TOC if parasite can be located

This can be combined with albendazole 400 mg daily or BID for 21 days

larva currens
Larva Currens
  • Intestinal infections with Strongloides stercoralis may be associated with a perianal larva migrans syndrome, called larva currens
  • Named because of the rapidity of larval migration currens means running or racing
  • An auto-infection caused by penetration of perianal skin by infectious larvae as they are excreted in feces
  • An urticarial band is primary lesion of cutaneous strongyloidiasis
larva currens163
Larva Currens
  • Often is a chronic disease
  • Has been reported to last 40 yrs or more
  • Symptoms include: abdominal pain, diarrhea, peripheral eosinophilia
  • Skin lesions originate within 30 cm of anus
  • Extend as much as 10cm/day
  • Fatal cases of hyper-infection occur in immunocompromised pts
  • Parasite load increases dramatically and can produce fulminant illness
  • Widespread petechiae and purpura and chronic urticaria may be a presenting sign of dissemination
larva currens164
Larva Currens
  • Tx: ivermectin 200 micrograms/kg/day for 2 days or albendazole 400 mg/day for 3 days=TOC
  • Immunosuppressed hosts may be tx with thiabendazole 25 mg/kg BID for 7-10 days
  • Guinea worm disease or medina worm
  • Endemic in India, southwest Asia, northeast South America, West Indies, and Africa
  • Caused by Dracunculus medinensis contracted through drinking water contaminated with infected water fleas in which Dracunculus is parasitic
  • In stomach, larvae penetrate into mesentery where they sexually mature in 10 weeks
  • Female worm burrows to cutaneous surface to deposit her larvae and causes skin manifestations
  • As worm approaches surface it may be felt as a cordlike thickening and forms an indurated cutaneous papule
  • Papule may vesiculate and a painful ulcer develops, usually on the leg
  • Worm is often visible
  • When parasite comes into contact with water, the worm rapidly discharges its larvae, which are ingested by water fleas (Cyclops), contaminating the water
  • Cutaneous lesion is usually on lower leg, but may occur on genitalia, buttocks, or arms
  • There may also be urticaria, gastrointestinal upsets, eosinophilia, and fever
  • Disease may be prevented by boiling water before drinking, providing safe drinking water through boreholes, or filtering water through mesh fibers
  • Native tx consists of gradually extracting the worm a little each day, with care not to rupture it
  • If ruptures larvae escape into tissues and produce fulminating inflammation
  • Surgical removal is TOC
  • Metronidazole 500 mg/day resolves inflammation and permits easier removal of worm; so does warm water immersion
  • Elephantiasis Tropica (elephantiasis Arabum)
  • Widespread tropical disorder caused by infestation by filarial worms of Wuchereria bancrofti, Brugia malayi, or B. timori
  • Characterized by lymphedema
  • Resulting in hypertrophy of skin & subcutaneous parts
  • Enlargement of affected areas usually legs, scrotum, labia majora
  • More common in men than women
  • Onset characterized by recurrent attacks of acute lymphangitis
  • Episodes last days –weeks
  • Occurs for months-yrs
  • After each attack swelling subsides only partially
  • As recrudescences supervene thickening and hypertrophy worsen
  • Overlying epidermis becomes stretched, thin, shiny
  • Over yrs becomes leathery, insensitive, verrucous or papillomatous from secondary pyogenic infection
  • Involvement may then involve scalp, vulva, penis, female breasts, arms
  • Legs are usually affected symmetrical manner
  • Thickening becomes massive and pachydermatous
  • Thickened integument hangs in apposing folds between which there is a fetid exudate
Scrotal involvement causes area to become enormous and penis becomes hidden in it
  • Skin, first glazed, later becomes coarse and verrucous or ulcerated or gangrenous
  • Resistant urticaria may occur
  • Filarial orchitis and hydrocele are common
  • Testicle may enlarge rapidly to apple size and can be painful
  • Swelling may subside within a few days, enlargement may be permanent
  • Resulting obstruction and dilation of thoracic duct may occur; obstruction of lower abdominal tributaries into urinary tract, chyle appears in urine
  • Lobulated swellings of inguinal and axillary glands, called varicose glands occur
  • These are caused by obstructive varix and dilation of lymphatic vessels
  • Filaria are transmitted person-to-person by bites of mosquitoes
  • Culex, Aedes, and Anopheles species
  • Adult worms are threadlike, cylindrical and creamy white
  • Females are 4-10 cm long
  • Microfilarial embryos may be seen coiled each in its own membrane near posterior tip
  • Fully grown, shealthed microfilariae are 130-320 microns long
  • Adult worms live in lymphatic system producing microfilariae
  • An intermediate host is needed fror further development of parasite
  • Endemic in Africa, India, South China, Japan, Samoa, Taiwan
  • Occurs also in West Indies and Costa Rica
  • In Malaya, Ceylon, Indonesia, China, and Korea there is Malayan filariasis caused by B. malayi
  • B. timori is restricted to eastern Indonesian archipelago
  • W. bancrofti or B. malayi has been known in India since the sixth century BC.
  • Estimated that 250 million people are infected with these parasites
  • Infestation often is asymptomatic
  • Elephantiasis usually occurs only if hundreds of thousands of mosquito bites are suffered over a period of yrs- with episodes of intercurrent streptococcal lymphangitis
  • There is a striking periodicity to time of appearance and disappearance of microfilariae in skin and superficial vessels
  • Cutex fatigans bites at night
  • Microfilariae of W. bancrofti are found in peripheral circulation at midnight (nocturnal periodicity) but rarely during daytime
  • In South Pacific, it is nonperiodic
  • Search for microfilariae should be made on fresh cover-slip films of blood from finger or ear and examined with a low-power objective lens
  • Specimens should be taken at midnight
  • Calcified adult worms may be seen on x-ray
  • Adult filariae are found in abscesses or in material taken for path exam
  • Filarial worm can be traced fluorescently as microfilariae and adult worms have an affinity for tetracyclines, which fluoresce in UV light in a dark room
  • Filarial complement fixation tests are useful in seeking the cause of lymphedema
Prognosis is good
  • Living may become burdensome unless condition is alleviated
  • Ivermectin, 100- 440 micrograms/kg in one dose=TOC
  • Regimen (as well as alternative tx with diethylcarbamzine) will clear microfilariae but not adult worms
  • Surgical operations have been developed to remove edematous subcutaneous tissue from scrotum and breast
  • Prophylactic measures consist of appropriate mosquito control; diethylcarbamazine has been effective in mass prophylaxis