trichuriasis

　

WordNet

1. infestation by a roundworm; common in tropical areas with poor sanitation

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/11/09 21:25:57」(JST)

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This article is about the disease. For for the organism, see Trichuris trichiura.

Not to be confused with Trichinosis or Trichomoniasis.

Trichuriasis
Classification and external resources
Life cycle of Trichuris trichiura.
ICD-10	B79
ICD-9	127.3
DiseasesDB	31146
MedlinePlus	001364
Patient UK	Trichuriasis
MeSH	D014257

Trichuriasis also known as whipworm infection is an infection by the parasitic worm Trichuris trichiura (whipworm). If infection is only with a few worms, there are often no symptoms. In those who are infected with many worms, there may be abdominal pain, tiredness and diarrhea. The diarrhea sometimes contains blood. Infections in children may cause poor intellectual and physical development. Low red blood cell levels may occur due to loss of blood.

The disease is spread by people eating food or water that contains the eggs of these worms. The eggs are in the feces of people infected with the worms and the disease is most common in areas of the world where human feces are used as fertilizer. The worms live in the large bowel and are about four centimetres in length. Whipworm is diagnosed by seeing the eggs when examining the stool with a microscope. Eggs are barrel-shaped.

Prevention is by properly cooking food and hand washing before cooking. Other measures include improving access to toilets and clean water. In areas of the world were the infections are common, often entire groups of people will be treated all at once and on a regular basis. Treatment is with three days of the medication: albendazole, mebendazole or ivermectin. People often become infected again after treatment.

Whipworm infections affects about 600 to 800 million people. It is most common in tropical countries. In the developing world those infected with whipworm often also have hookworms and ascariasis infections. They have a large effect on the economy of many countries. Work is ongoing to develop a vaccine against the disease.

Signs and symptoms

• Light infestations (<100 worms) frequently have no symptoms.
• Heavier infestations, especially in small children, can present gastrointestinal problems including abdominal pain and distension, bloody or mucus-filled diarrhea, and tenesmus (feeling of incomplete defecation, generally accompanied by involuntary straining). While damage may be done to the GI tissue and appendicitis may be brought on (by damage and edema of the adjacent lumen) if there are large numbers of worms or larvae present, it has been suggested that the embedding of the worms into the ileo-cecal region may also make the host susceptible to bacterial infection. Severe infection may also present with rectal prolapse, although this is typically seen only in heavy infections of small children. High numbers of embedded worms in the rectum cause edema, which causes the rectal prolapse. The prolapsed, inflamed and edematous rectal tissue may even show visible worms.
• Growth retardation, weight loss, nutritional deficiencies, and anemia (due to long-standing blood loss) are also characteristic of infection, and these symptoms are more prevalent and severe in children. It does not commonly cause eosinophilia.
• Coinfection of Trichuris trichiura with other parasites is common and with larger worm burdens can cause both exacerbation of dangerous trichuriasis symptoms such as massive gastrointestinal bleeding (shown to be especially dramatic with coinfection with Salmonella typhi) and exacerbation of symptoms and pathogenesis of the other parasitic infection (as is typical with coinfection with Schistosoma mansoni, in which higher worm burden and liver egg burden is common). Parasitic coinfection with HIV/AIDS, tuberculosis, and malaria is also common, especially in Sub-saharan Africa, and helminth coinfection adversely affects the natural history and progression of HIV/AIDS, tuberculosis, and malaria and can increase clinical malaria severity. In a study performed in Senegal, infections of soil-transmitted helminths like Trichuris trichiura (as well as schistosome infections independently) showed enhanced risk and increased incidence of malaria.

• Heavy infestations may have bloody diarrhea.
• Long-standing blood loss may lead to iron-deficiency anemia.
• Rectal prolapse is possible in severe cases.
• Vitamin A deficiency may also result due to infection.

Mechanical damage to the mucosa may occur as well as toxic or inflammatory damage to the intestines of the host.

Cause

The phylum of Trichuris trichiura is Aschelminthes, its class is Adenophorea, its order is Stichosmida, and its family is Trichocephaloidea. The genus was formerly known as Trichocephalus, a more accurate name; however the generic name is now Trichuris, which means “hair tail” (impying that the posterior end of the worm is the attenuated section).

Reservoir

Humans are the main, but not the only reservoir for T. trichiura. Recent research verified by the application of molecular techniques (PCR) that dogs are a reservoir forT. trichiura, as well as T. vulpis.

Vector

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.

Transmission

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).

Life cycle

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.

Incubation period

• The exact incubation period of Trichuris trichiura is unknown, however immature eggs in soil under favorable conditions take about three weeks to mature: 15–30 days, 10 days minimum to mature before ideal ingestion by the human host. Favorable conditions for maturation of eggs is warm to temperate climates with adequate humidity or precipitation, as ova are resistant to cold, but not resistant to drying.
• Once ingested, the larva will remain dug into a villus in the small intestine for about 2–3 days until it is fully developed for migration to the ileo-cecum section of the gastrointestinal tract.
• The average total life span of Trichuris trichiura is one year, although there have been longer cases reported, lasting as long as five years (Note: inadequate treatment and re-infection are likely to play a role in this).

Morphology

Trichuris trichiura egg

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 eggs are prolate spheroids, the shape of the balls used in Rugby and Gridiron football. They are about 50-54 um long and have polar plugs (also known as refractile prominences) at each end.

Diagnosis

• A stool ova and parasites exam reveals the presence of typical whipworm eggs. Typically, the Kato-Katz thick-smear technique is used for identification of the Trichuris trichiura eggs in the stool sample.
• Although colonoscopy is not typically used for diagnosis, as the adult worms can be overlooked, especially with imperfect colon, there have been reported cases in which colonoscopy has revealed adult worms. Colonoscopy can directly diagnose trichuriasis by identification of the threadlike form of worms with an attenuated, whip-like end. Colonoscopy has been shown to be a useful diagnostic tool, especially in patients infected by only a few male worms and with no eggs presenting in the stool sample.

Trichuriasis can be diagnosed when T. trichiura eggs are detected in stool examination. Eggs will appear barrel-shaped and unembryonated, having bipolar plugs and a smooth shell. Rectal prolapse can be diagnosed easily using defecating proctogram and is one of many methods for imaging the parasitic infection. Sigmoidoscopy show characteristic white bodies of adult hanging from inflamed mucosa (coconut cake rectum).

Prevention

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.

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 geohelminthinfection, 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.

Infection can be avoided by proper disposal of human feces, avoiding fecal contamination of food, not eating dirt, and avoiding crops fertilized with night soil. Simple and effective proper hygiene such as washing hands and food is recommended for control.

Management

The highest clearance rates are obtained by combining mebendazole or albendazole with ivermectin. Ivermectin’s safety in children under 15 kg and pregnant women has not yet been established.

People with diarrhea may be treated with loperamide to increase the amount of drug contact with the parasites.

Mebendazole is 90% effective in the first dose, and albendazole may also be offered as an anti-parasitic agent. Adding iron to the bloodstream helps solve the iron deficiency and rectal prolapse. Difetarsone is also an effective treatment.

Epidemiology

Disability-adjusted life year for trichuriasis per 100,000 inhabitants in 2004.

  no data

  less than 5

  5-10

  10-15

  15-20

  20-25

  25-30

  30-35

  35-40

  40-45

  45-50

  50-60

  more than 60

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.

History

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).

Synonyms

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.

Research

Development of subunit vaccines requires the identification of protective antigens and their formulation in a suitable adjuvant. Trichuris muris is an antigenically similar laboratory model for T. trichiura. Subcutaneous vaccination with adult excretory–secretory products (ES) protects susceptible mouse strains from T. muris. Larval stages may contain novel and more relevant antigens which when incorporated in a vaccine induce worm expulsion earlier in infection than the adult worm products. Nematode vaccines marketed to date have been of the irradiated larval type and used exclusively for the treatment of animals. These vaccines are not stable and require annual production, involving the yearly production and sacrifice of donor animals for passage. There has been much interest in the production of subunit vaccines against human and agricultural parasites since the early 1980s. Development of subunit vaccines requires the identification of protective antigens and their formulation with a suitable adjuvant to stimulate the immune response appropriately.

References

External links

• http://www.gastrointestinalatlas.com/English/Colon_and_Rectum/Parasites/parasites.html

UpToDate Contents

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• 1. 蟯虫症および鞭虫症 enterobiasis and trichuriasis
• 2. 駆虫薬療法 anthelminthic therapies
• 3. 成人におけるステロイド抵抗性およびステロイド依存性の潰瘍性大腸炎に対するアプローチ approach to adults with steroid refractory and steroid dependent ulcerative colitis
• 4. 集団寄生虫駆除 population deworming
• 5. 小児における直腸脱の概要 overview of rectal prolapse in children

English Journal

• Glucose Absorption by the Bacillary Band of Trichuris muris.

• Hansen TV1, Hansen M2, Nejsum P1, Mejer H1, Denwood M3, Thamsborg SM1.
• PLoS neglected tropical diseases.PLoS Negl Trop Dis.2016 Sep 2;10(9):e0004971. doi: 10.1371/journal.pntd.0004971. eCollection 2016.
• BACKGROUND: A common characteristic of Trichuris spp. infections in humans and animals is the variable but low efficacy of single-dose benzimidazoles currently used in mass drug administration programmes against human trichuriasis. The bacillary band, a specialised morphological structure of Trichur
• PMID 27588682

• Identification of lead chemotherapeutic agents from medicinal plants against blood flukes and whipworms.

• Wangchuk P1, Giacomin PR1, Pearson MS1, Smout MJ1, Loukas A1.
• Scientific reports.Sci Rep.2016 Aug 30;6:32101. doi: 10.1038/srep32101.
• Schistosomiasis and trichuriasis are two of the most common neglected tropical diseases (NTD) that affect almost a billion people worldwide. There is only a limited number of effective drugs to combat these NTD. Medicinal plants are a viable source of parasiticides. In this study, we have investigat
• PMID 27572696

• Approved oncology drugs lack in vivo activity against Trichuris muris despite in vitro activity.

• Cowan N1,2, Raimondo A1,2, Keiser J3,4.
• Parasitology research.Parasitol Res.2016 Aug 8. [Epub ahead of print]
• Infections with soil-transmitted helminths (STHs) are considered among the most persistent global health problems. The few available drugs have limitations including low efficacy against Trichuris trichiura infections. As a starting point toward drug repositioning, we studied a set of FDA-approved o
• PMID 27498843

Japanese Journal

• 豚鞭虫卵に汚染された堆肥による子豚の豚鞭虫症の発生事例

• 日本獣医師会雑誌 67(4), 259-262, 2014
• NAID 130004888063

• 出血を伴う巨大潰瘍を合併した直腸鞭虫症の1例

• 日本消化器内視鏡学会雑誌 = Gastroenterological endoscopy 51(8), 1725-1729, 2009-08-20
• NAID 10025171380

• 大腸内視鏡下に摘出した鞭虫症の1例

• Progress of Digestive Endoscopy 73(2), 166-167, 2008
• NAID 130004652589

Related Links

• Trichuriasis | Define Trichuriasis at Dictionary.com

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• trichuriasis - definition of trichuriasis by Medical dictionary

trichuriasis /trich·u·ri·a·sis/ (trik″u-ri´ah-sis) infection with Trichuris, often asymptomatic in adults but with gastrointestinal symptoms in children. trich·u·ri·a·sis (trĭk′yə-rī′ə-sĭs) n. pl. trich·u·ri·a·ses (-sēz) Infection with a nematode. It is ...

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★リンクテーブル★

リンク元

「鞭虫」

「鞭虫」

　　[★]

英

whipworm、Trichuris、Trichuris trichiura

関

鞭虫属、鞭虫類、Trichuris属、トリチュリス属

関

trichuriasis