Nematodes Gregory L. Brower, D.V.M., Ph.D. Cell Biology and Anatomy School of Medicine Columbia, South Carolina
Parasitology Resources • World Health Organization • http://www.who.int/en/ • Centers for Disease Control • http://www.cdc.gov/ • http://www.dpd.cdc.gov/dpdx/ • Kansas State University • http://www.k-state.edu/parasitology/ • Atlas of Medical Parasitology • http://www.cdfound.to.it/html/atlas.htm
Parasitology Resources • World Health Organization • Training Manual on Diagnosis of Intestinal Parasites http://www.who.int/wormcontrol/documents/benchaids/training_manual/en/ • United States Military • http://www.phsource.us/PH/TM/index.htm • http://www.phsource.us/PH/PARA/index.htm • Parasitology Autotutorial • http://workforce.cup.edu/buckelew/ • Pubmed and Journal Case Studies
At Risk Populations • Developing Countries • Tropics • Southern United States • Institutional settings (e.g. daycares) • Newly arrived persons • Travelers • Immigrants • Refugees
Number of Specimens Positive For Parasites Year Ascaris Hookworm Trichuris Pinworm 1974-77 3,713 285 1,321 ? 1990-94 572 88 238 ? Incidence of Parasitic Worm Infections in South Carolina
~200000/day AscarislumbricoidesLife Cycle
Symptoms Organ involved Small and large intestine Abdominal pain; distended abdomen, anorexia, weight loss, occasional vomiting and loose stool Pulmonary Cough wheezing, dyspnea, substernal discomfort Symptoms of Ascariasis
50 :m AscariasisDiagnosis characteristic corticoid eggs in the stool
AscariasisPrevention and Treatment • Good Hygiene • Anthelmintics: • Mebendazole • Albendazole • Ivermectin
Trichinosis Geographical Distribution • World-wide distribution • Not common in Muslim countries • Related To: • Hog Farming Conditions • Pork Consumption
Trichinosis: Case-1 • A 54 year old man who resided in Franklin County. The patient had been hospitalized a 3-week history of diaphoresis, fever, weakness, tachycardia, diarrhea, an 8-pound weight loss, and dry cough. Laboratory testing indicated an elevated white blood cell (WBC) count (20,600/mm3 with 33% eosinophils), hyponatremia), elevated lactate dehydrogenase and elevated creatininephosphokinase. • The patient reported eating 2 pounds of nearly raw bear meat during several meals 2 weeks earlier. Because of suspicion of trichinellosis, albendazole and corticosteroids were administered and the patient recovered fully by February 2004.
Trichinosis: Case-2 • 38 year old man and a woman aged 54 years were admitted to a hospital with 7- and 14-day histories , respectively, of: fever, chills, headache, myalgias, arthralgias, and facial swelling. • The man's WBC count was 14,600/mm3, with 24% eosinophils, 13% lymphocytes, and 2% monocytes. • The woman's WBC count was 16,200/mm3, with 28% eosinophils, 13% lymphocytes, and 3% monocytes. • Serum obtained from both patients tested positive for Trichinella antibodies. • Both were started on a course of albendazole and corticosteroids and recovered fully.
Trichinosis: Case-2 Questioning of the patients revealed that the man had shot a black bear in Canada. The bear was field dressed, and selected meat was packed on ice for transport to Tennessee. The wife prepared and cooked the bear meat on an outdoor grill for themselves and four other persons. The man and woman ate their steaks medium rare; while the other four ate their steaks well done. The meat was examine histologically and numerous Trichinella larvae were observed encysted in characteristic hyalinized capsules in the striated muscle tissue.
Trichinosis: Diagnosis • Symptoms • Recent history of eating under-cooked pork, seal or bear • Eosinophilia • Increased serum creatinine phosphate and lactate dehydrogenase • Positive serology
Worm Location Symptoms intestinal mucosa nausea, vomiting, abdominal pain, diarrhea, head ache circulation Edema, periorbital conjunctivitis, photophobia,fever, chill, sweating, muscle pain, spasm, eosinophilia Chest pain, tachycardia, edema, vascular thrombosis myocardium Head ache (supraorbital), vertigo, tinnitus, deafness, mental apathy, delirium, coma, loss of reflexes brain Trichinosis:Symptoms
Trichinella • Muscle invasion stage 2 to 8 weeks after infection. Fever and perorbital edema are followed by myalgia (muscle pain) and weakness. • Characteristic splinter hemorrhages can be found under finger nails (DDX – endocarditis). • Fever and chills can persist for weeks. • Headache is common and dizziness may develop. • Deaths are rare and due to myocarditis, encephalitis and pneumonia (larvae in the diaphragm).
Trichinosis: Treatmentand Prevention Prevention • Elimination of parasite from hogs • Cooking meat well • Freeze pork immediately after packaging Treatment • Corticosteroids for symptomatic relief • Albendazole or Mebendazole for killing parasite
TrichuriasisEpidemiology • A tropical disease, primarily of children • 65% of 1 billion cases seen in Asia and Africa • Seen is rural (low country) South Carolina • Caused by Trichuris trichura (whipworm)
3000-10000/day TrichuristrichuraLife Cycle
TrichuristrichuraSymptoms • Abdominal pain • Chronic profuse diarrhea with mucus and blood • Weight loss and anemia • Prolapsed rectum
10 :m TrichuristrichuraDiagnosis Symptoms Examine stool for eggs
TrichuristrichuraPrevention and Treatment • Prevention: • Sanitary eating habits • Improved hygiene • Treatment • Mebendazole is effective
PinwormEpidemiology • World-wide, primarily in children • Urban disease in crowded environment • Enterobiusvermicularis
~10,000/day EnterobiusvermicularisLife Cycle
EnterobiusvermicularisSymptoms • Perianal, perineal and vaginal irritation • Insomnia and restlessness • Occasionally mild abdominal pain, nausea and vomiting
EnterobiusvermicularisPinwormNeurosis Mental distress, guilt complex, and desire to conceal knowledge of the infection from others are perhaps the most significant trauma caused by this persistent, pruritic parasite.
EntrobiusvermicularisDiagnosis Nocturnal observation
EntrobiusvermicularisDiagnosis Scotch tape test for eggs
50 :m EntrobiusvermicularisDiagnosis Scotch tape test for eggs
EntrobiusvermicularisPrevention and Treatment • Improved hygiene is preventive • Pyrentalpalmoate is very effective • Mebendazole is an alternative
Strongyloides stercoralis Epidemiology • Prevalent in the tropics • Southern US and Puerto Rico
Site Symptoms Pathogenesis Itching and red blotches Cutaneous invasion and sub‑cutaneous migration of larva Skin Verminous pneumonitis Migration of larvae through lung, bronchi, and trachea Pulmonary GI tract Mid-epigastric pain; nausea and vomiting; diarrhea/constipation; bloody dysentery. Attachment of adult worms and injury to upper intestinal mucosa General Weight loss and anemia (rare) Loss of nutrients and blood StrongyloidesstercoralisSymptoms
Strongyloides stercoralis Diagnosis Larvae in stool
StrongyloidesstercoralisPrevention and Treatment • Improved hygiene is preventive • Treatment: • Ivermectin • Albendazole