Chapter 56 Paragonimiasis Lung Fluke Kimberly Hayden Biol 423 SP 2010
General Characteristics Class: Trematodes Red/Brown short, leaf-like worm Bilateral symmetry Operculated eggs -golden brown Discovery (2010)
Morphology Two suckers: oral and ventral aid in attachment and locomotion Hermaphrodite: ovaries above testes and on the right side of body Rohde (2010)
History Paragonimiasis has infected 22 million people globally. Discovered by Kerbert 1878 in the lungs of Bengal tigers from India, which had later died in a zoo.
Geographic Distribution Far East: Japan, China, Taiwan, Indonesia, Manchuria, New Guinea, Philippines, and other areas of Southeast Asia Recent spread to : Latin America P. mexicanus South America Africa P. africanus Eastern U.S. and Canada: P. kellicotti -rarely results in human infection Baumann (2001)
Epidemiology High prevalence in the Far East due to cultural eating habits and proximity to infected crabs/crayfish. Food preparation such as drunken crab or crab soaked in soybean-sauce will not kill Paragonimiasis. Spread by contamination by crab juice to other work areas.
Epidemiology- South Korea Paragonimiasis was widespread across S. Korea by the late 1960’s. Industrialization in the 1970’s and 1980’s caused runoff polluting many streams. Pollution killed many crab and crayfish almost to extinction. Subsequently, rates of those infected by Paragonimiasis dramatically decreased to 1/100th of previous numbers. TODAY: A priority on health education and surveillance to control infection rates.
Pathogenesis The Imaging of Tropical Diseases
Pathogenesis • Eggs are excreted from human host -found in stool or sputum -golden eggs are coughed up along with blood -eggs must find their way to a freshwater source -upon finding fresh water the eggs will hatch and turn into ciliated larvae: miracidia
Pathogenesis 2. Primary host: SnailApprox. 3-5 months -miracidia infect the snail -asexual reproduction inside snail results in thousand of larvae: cercariae -cercariae leave the snail and swim around until they find the secondary host Thompson (2004)
Pathogenesis 3. Secondary Host: Freshwater crab/crayfish Approx. 6-8 weeks -cercariae infect crab and undergo a second transformation -transformation into the infective stage: metacercariae -infected crab ingested by human France-Presse (2007)
Pathogenesis 4. Human infection - once ingested the metacercariae burrow themselves through the gut and eventually up into the lungs* - in the lungs they will reach maturity in 5-6 weeks - flukes encapsulate themselves and lay eggs -capsules burst into the bronchioles to be coughed up *migration to other sites possible, most commonly the brain
Manifestations/Diagnositc Indicators Migration stage:nonspecific symptoms -diarrhea -abdominal & chest pain -allergic rxn - fever & chills Once Established in Lungs:elicit eosinophilic inflammatory rxn -one or more parasites become encapsulated in 1-2cm lesions -secondary infections occur after capsules burst : may clinically appear as chronic bronchitis -cough -night sweats -haemoptyisis -general malaise Severe Infections: -pleurisy -persistent rales -clubbed fingers -pneumothorax *Ectopic infection in the brain will exhibit neurological symptoms: paralysis, epilepsy, homonymous hemianopsia, optic atrophy, papilledema (brain infections occur most commonly in children)
Paragonimiasis vs. TB 10-20% of radiograph findings will be normal Abnormal Findings: Most show infiltrates that eventually lead to calcification and look clinically similar to TB on x-rays Many cases of P. westermani are diagnosed after TB treatment has failed, therefore a careful differential diagnosis is key in determining Paragonimiasis infections. HeathToKnow (2008)
Definitive Diagnosis 75% of infected individuals will have eggs detectible in their sputum after the first 3 months have passed so retesting of sputum is necessary Complement Fixation (CF) Test: standard test; sensitive and good indicator of cure Enzyme Immunoassay Tests: antibodies -can be used but cannot distinguish between past and current infection Immunoblot (IB) assay: antibodies Used by CDC but may not be able to detect for other species of Paragonimiasis besides P. westermani
Treatment and Prevention Bithionol:phenol drug class - uncouples phosphorylation - NOT available in the United States Praziquantel:causes severe spasms and paralysis of the worms muscles- worms destroyed in intestines or excreted in feces Dosage: 25mg/kg 3 times a day-3 days >90% effective in case studies PREVENTION: adequate cooking of shellfish before consuming.
Text Sources • Cho, SY. “Epidemiology of paragonimiasis in Korea.” U.S. National Library of Medicine National Institutes of Health. 1997. Accessed 04/21/2010. <http://www.ncbi.nlm.nih.gov/pubmed/9656345> • Ghaffar, Dr. Abdul and Dr. Gregory Brower. “Parasitology-Chapter Six Trematodes.” Microbiology and Immunology On-line: University of South Carolina School of Medicine. Updated April 15, 2010. Accessed: 04/19/2010. <http://pathmicro.med.sc.edu/parasitology/trematodes.htm> • Govinden, Kughan. “The Human Lung Fluke- Paragonimus Westermani (Domain Eukarya, Kingdom Animalia, Phylum Plathyhelminthes, Class Trematoda).” The Macrae Group LLC. 2009. Accessed 04/19/2010. < http://www.themacraegroup.com/2009-symposia/xi-international- symposium-on-respiratory-viral-infections/poster-abstracts/the-human-lung-fluke-2013- paragonimus-westermani-domain-eukarya-kingdom-animalia-phylum-plathyhelminthes-class- trematoda> • Micromedex. “Praziquantel (Oral Route).” MayoClinic.com. 11/1/2009. Accessed: 4/21/2010. < http://www.mayoclinic.com/health/drug-information/dr601147> • Ryan, Kenneth J. and George Ray. “Trematodes.” Sherris Medical Microbiology Fifth ed. McGraw-Hill Companies, Inc. 2010. 776-777, 879-884. • Sadun, Elvio H. and Alfred A. Buck. “Paragonimiasis in South Korea- Immunodiagnostic, Epidemiologic, Clinical, Roentgenologic and Therapeutic Studies.” The American Journal of Tropical Medicine and Hygiene. 1960. Accessed 04/20/2010. < http://www.ajtmh.org/cgi/content/abstract/9/6/562> • Singh, TN. “Pleuropulmonary Paragonimiasis Mimicking Pulmonary Tuberculosis- A Report of Three Cases.” Indian Journal of Medical Microbiology. 2005. Accessed 04/21/2010. < http://medind.nic.in/iau/t05/i2/iaut05i2p131.pdf> • Slemenda, SB. “Paragonimiasis: Antibody Detection.” Diagnostic Findings. Accessed: 4/20/2010. < http://www.dpd.cdc.gov/dpdx/html/frames/M- R/Paragonimiasis/body_Paragonimiasis_serol1.htm>
Picture Sources Baumann (2001) http://www.stanford.edu/class/humbio103/ParaSites2001/paragonimiasis/Paragonimiasis_Home.html HealthToKnow (2008) http://www.health2know.com/mini-lobsters/ Discovery (2010) http://animal.discovery.com/invertebrates/monsters-inside-me/lung-fluke-paragonimus-westermani/ France-Presse (2007) http://www.cosmosmagazine.com/news/1375/freshwater-crabs-thrive-roman-ruins Rohde (2010) http://knol.google.com/k/flukes-trematodes-the-biology-morphology-and-medical-economic-importance-of# The Imaging of Tropical Diseases http://www.isradiology.org/tropical_deseases/tmcr/chapter22/epidemiology.htm Thompson (2004) http://www.flmnh.ufl.edu/malacology/fl-snail/snails1.htm