Trichostrongyloidosis: causes, symptoms, diagnosis, treatment

Trichostrongyloidiasis is a zoonosis-geohelminthiasis. Humans are optional hosts. Adult helminths are localized in the small intestine of humans.

Causes of trichostrongyloidiasis. Humans are mainly parasitized by Trichostrongylus colubriformis. Trichostrongylids are small nematodes measuring 4-8 x 0.78-1 mm. The oral opening is limited by three lips. Males have a bursa at the rear end, two brownish spicules of unequal size and a rudder that directs their movement.

Helminth eggs are oval, 74-80 x 40-43 microns in size, covered with a thin transparent shell, with one slightly pointed end and the other blunt.

Development cycle. Trichostrongylidae parasitize, as a rule, in the organism of obligate hosts - small and large cattle and other herbivorous mammals. Sometimes humans become infected, who are optional hosts for this helminth. Humans become infected with trichostrongyloidiasis when eating plants contaminated with invasive larvae. Development occurs without migration. In the human intestine, the larvae penetrate the mucous membrane of the duodenum, develop, molt twice and turn into sexually mature helminths. After 20-30 days, eggs can be found in the patient's feces. The lifespan of helminths is more than 8 years.

Epidemiology of trichostrongyloidiasis. The role of humans as a source of invasion is small. Larvae enter the human body quite rarely and in small quantities.

Trichostrongyloidiasis occurs in countries with a warm and humid climate in Southeast Asia, North Africa, the Middle East, South, Central and North America, Armenia, Azerbaijan, Uzbekistan, the Volga region, and the Far East. Of the many existing species of trichostrongylids, 13 species have been found to be infected in humans. Residents of rural areas with well-developed livestock farming are more likely to get sick. The source of infection is herbivores, cattle and small ruminants that pollute pastures, barnyards, and stalls with helminth eggs. In the external environment, under favorable conditions (sufficient humidity, oxygen, and an optimal temperature of 30-32 °C), larvae develop in the eggs. After 1-3 days, they emerge from the egg membranes, molt twice, and within 4-14 days turn into invasive, filariform larvae. In the environment, the larvae can survive for 3-4 months. They can migrate vertically and horizontally and remain viable in the soil for a year. The factors of pathogen transmission are vegetables, fruits, and grasses contaminated with helminth larvae during agricultural work.

Infection with trichostrongyloidiasis occurs when eating fruits, vegetables, sorrel and other herbs contaminated with nematode larvae. Humans do not play a major role in the spread of this disease.

Pathogenesis. Helminths, penetrating the mucous membrane of the duodenum and jejunum, injure it. Symptoms arise due to the toxic-sensitizing effect of nematodes, and inflammatory processes may also develop.

Symptoms of trichostrongyloidiasis

The intensity of invasion in humans is usually low. The course of trichostrongyloidiasis is asymptomatic or has a subclinical form. In case of intensive infection, symptoms of gastrointestinal tract damage predominate. Patients note lack of appetite, nausea, belching, abdominal pain, diarrhea, irritability, weakness, weight loss. Sometimes hypochromic anemia, leukocytosis, eosinophilia develop.

Differential diagnostics. Differential diagnostics is carried out with ankylostomiasis.

Laboratory diagnostics. The diagnosis is made when eggs are found in the feces. The enrichment method is used, since the intensity of invasion is low. Cultivation of larvae on filter paper using the Harada and Mori method is also used. Sometimes helminth eggs are found in the duodenal contents.

Complications: Severe anemia, cachexia.

Treatment of trichostrongyloidiasis. Treatment is carried out with broad-spectrum nematicides (albendazole, mebendazole, medamin, pyrantel, etc.) according to the same schemes as for ascariasis.

Prevention. Prevention is similar to the prevention of other geohelminthiases (ascariasis, ancylostomiasis, etc.).