| Trichuriasis | |
|---|---|
| Classification and external resources | |
Life cycle of Trichuris trichiura. Source: CDC |
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| ICD-10 | B79 |
| ICD-9 | 127.3 |
| DiseasesDB | 31146 |
| MeSH | D014257 |
Trichuriasis is a parasitic infection primarily in the tissue of the cecum, appendix, colon and rectum that is caused by Trichuris trichiura (whipworm), an intestinal parasitic nematode (roundworm).
The phylum of Trichuris trichiura is Aschelminthes, while its class is Adenophorea, its order is Stichosmida, and its family is Trichocephaloidea. Its genus, Trichocephalus, was recorded as a more accurate name, however the generic name trichuris, which means “hair tail” (which implies that the posterior end of the worm is the attenuated section), remains the dominant name form used today.
Human Whipworm, Trichocephaliasis, and Tricuriasis are all synonyms for Trichuriasis, human infection of the Trichuris trichiura intestinal nematode. In Spanish, trichuriasis is called “Tricuriasis,” while in it is known as “Trichuriose” in French and “Peitschenwurmbefall” in German.
The first written record of Trichuris trichiura was made by Morgani, an Italian scientist, who identified the presence of the parasite in a case of worms residing in the colon in 1740. Exact Morphological description and figures were first recorded in 1761 by Roedere, a German physicist. Soon after morphology and visual representation of the worms, Trichuris trichiura was given taxonomy (during the 18th century).
Humans are the main, but not the only reservoir for T. trichiura. As identification by microscopy is unreliable due to near identical sizes of different species of Trichuris spp. Recent research verified by the application of molecular techniques (PCR) that dogs are a reservoir for T. trichiura, as well as T. vulpis [1] .
Non-biting cyclorrhaphan flies (Musca domestica, Chrysomya rufifacies, Musca sorbens, Lucina cuprina, Calliphora vicina, Chrysomya bezziana and Wohlfarthia magnifica) have been found to carry Trichuris trichiura. A study in two localized areas in Ethiopia found cockroaches were carriers for several human intestinal parasites, including Trichuris trichiura.
Humans can become infected with the parasite due to ingestion of infective eggs by mouth contact with hands or food contaminated with egg-carrying soil. However, there have also been rare reported cases of transmission of trichuris trichiura by sexual contact. Some major outbreaks have been traced to contaminated vegetables (due to presumed soil contamination).
Unembryonated eggs (unsegmented) are passed in the feces of a previous host to the soil. In the soil, these eggs develop into a 2-cell stage (segmented egg) and then into an advanced cleavage stage. Once at this stage, the eggs embryonate and then become infective, a process that occurs in about 15 to 30 days). Next, the infective eggs are ingested by way of soil-contaminated hands or food and hatch inside the small intestine, releasing larvae into the gastrointestinal tract. These larvae burrow into a villus and develop into adults (over 2–3 days). They then migrate into the cecum and ascending colon where they thread their anterior portion (whip-like end) into the tissue mucosa and reside permanently for their year-long life span. About 60 to 70 days after infection, female adults begin to release unembryonated eggs (oviposit) into the cecum at a rate of 3,000 to 20,000 eggs per day, linking the life cycle to the start.
Adult worms are usually 3–5 cm long, with females being larger than males as is typical of nematodes. The thin, clear majority of the body (the anterior, whip-like end) is the esophagus, and it is the end that the worm threads into the mucosa of the colon. The widened, pinkish gray region of the body is the posterior, and it is the end that contains the parasite’s intestines and reproductive organs. Trichuris trichiura has characteristic football-shaped eggs, which are about 50-54 um long and contain polar plugs (also known as refractile prominences) at each end.
The highest clearance rates are obtained by combining mebendazole or albendazole with ivermectin.[1] Ivermectin’s safety in children under 15 kg and pregnant women has not yet been established.
Diarrheic patients may be treated with Imodium (loperamide hydrochloride) to increase the amount of drug contact with the parasites.
Trichuris trichiura is the third most common nematode (roundworm) of humans. Infection of trichuris trichiura is most frequent in areas with tropical weather and poor sanitation practices. Trichuriasis occurs frequently in areas in which human feces is used as fertilizer or where defecation onto soil takes place. Trichuriasis infection prevalence is 50 to 80 percent in some regions of Asia (noted especially in China and Korea) and also occurs in rural areas of the southeastern United States. Infection is most prevalent among children, and in North America, infection occurs frequently in immigrants from tropical or sub-tropical regions. It is estimated that 600-800 million people are infected worldwide with 3.2 billion individuals at risk.
Improved facilities for feces disposal have decreased the incidence of whipworm. Handwashing before food handling, and avoiding ingestion of soil by thorough washing of food that may have been contaminated with egg-containing soil are other preventive measures. Mass Drug Administration (preventative chemotherapy) has had a positive effect on the disease burden of trichuriasis in East and West Africa, especially among children, who are at highest risk for infection. Improvement of Sewage and Sanitation systems, as well as improved facilities for feces disposal have helped to limit defecation onto soil and contain potentially infectious feces from bodily contact. A study in a Brazil Urban Centre demonstrated a significant reduction in prevalence and incidence of geohelminth infection, including trichuriasis, following implementation of a city-wide sanitation program. A 33% reduction in prevalence of trichuriasis and a 26% reduction in incidence of trichuriasis was found in the study performed on 890 children ages 7–14 years old within 24 different sentinel areas chosen to represent the varied environmental conditions throughout the city of Salvador, Bahia, Brazil. Control of Soil Fertilizers has helped eliminate the potential for contact with human fecal matter in fertilizer in soil.
Limited access to essential medicine poses a challenge to the eradication of trichuriasis worldwide. Also, it is a public health concern that rates of post-treatment re-infection need to be determined and addressed to diminish the incidence of untreated re-infection. Lastly, with mass drug administration strategies and improved diagnosis and prompt treatment, detection of emergence of antihelmintic drug resistance should be examined.
John, David T. and Petri, William A.. Markell and Voge’s Medical Parasitology. Ninth Edition. Philadelphia, PA: Saunder Elsevier, Inc., 2006. http://commons.wikimedia.org/wiki/File:Trichuriasis_world_map_-_DALY_-_WHO2002.svg http://www.dpd.cdc.gov/dpdx/HTML/Trichuriasis.htm http://web.gideononline.com/web/epidemiology/ http://www.gastrointestinalatlas.com/English/Colon_and_Rectum/Parasites/parasites.html Joo JH,Ryu KH,Lee YH,Park CW,Cho JY,Kim YS,Lee JS,Lee MS,Hwang SG,Shim CS. “Colonoscopic diagnosis of whipworm infection.” Hepatogastroenterology 1998;45:2105–2109. Ok KS, Kim YS, Song JH, Lee JH, Ryu SH, Lee JH, Moon JS, Whang DH, Lee HK. “Trichuris trichiura Infection Diagnosed by Colonoscopy: Case Reports and Review of Literature.” Korean J Parasitol. 2009 Sep;47(3):275-280 “Trichuriasis.” Drugs for Parasitic Infection. New Rochelle, NY:The Medical Letter Inc., 2007. Hotez Peter J. M.D., Zheng Feng, Long-qi Xu, Ming-gang Chen, Shu-hua Xiao, Shu-xian Liu, Blair David, McManus Donald P., and Davis George M. “Emerging and Reemerging Helminthiases and the Public Health of China.” Emerging Infectious Disease. Volume 3, Number 3 (July–November 1997). Fetene T, Worku N. “Public health importance of non-biting cyclorrhaphan flies.” Trans R Soc Trop Med Hyg 2008 Sep 23. Kinfu A, Erko B. “Cockroaches as carriers of human intestinal parasites in two localities in Ethiopia.” Trans R Soc Trop Med Hyg 2008 Jun 23. Hotez Peter J. M.D., Molyneux David H Ph.D. D.Sc., Fenwick Alan Ph.D., Kumaresan Jacob M.B., B.S., D.P.H, Sachs Sonia Ehrlich M.D., Sachs Jeffrey D. Ph.D., and Savioli Lorenzo M.D. “Control of Neglected Tropical Diseases.” The New England Journal of Medicine 2007;357:1018:27. Mascarini-Serra L.M., Telles CA, Prado MS, Mattos SA, Strina A, Alcantara-Neves NM, and Barreto ML. “Reductions in the prevalence and incidence of geohelminth infections following a city-wide sanitation program in a Brazilian Urban Centre.” PLoS Neglected Tropical Diseases 2010 Feb 2; 4(2):c588. Nimir AR, Aziz MS, Tan GC, Shaker AR. “Massive lower gastrointestinal bleeding attributable to heavy whipworm infection and Salmonella typhi co-infection: a case report." Cases J. 2009 Sep 16;2:8285. Bickle QD, Solum J, Helmby H. “Chronic intestinal nematode infection exacerbates experimental Schistosoma mansoni infection.” Infect Immun. 2008 Dec;76(12):5802-9. Epub 2008 Sep 29. Whipworm Infection. MedlinePlus Medical Encyclopedia. US Federal Government public. domain. Update Date: 7/16/2004. Updated by: Daniel Levy, M.D., Ph.D., Infectious Diseases, Greater Baltimore Medical Center, Baltimore, MD. Review provided by VeriMed Healthcare Network. “Trichuriasis.” Drugs for Parasitic Infection. New Rochelle, NY:The Medical Letter Inc., 2007.
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