What is Trichocephalosis (Trichurosis)?
Trichurosis (trichocephalosis, trichiuriasis) is a helminthiasis from the group of nematodoses, characterized by predominant dysfunction of the gastrointestinal tract and the nervous system. It is widespread everywhere, especially in the humid zones of the temperate, subtropical and tropical belts.
Causes of Trichocephalosis (Trichurosis)
The causative agent of trichocephalosis is a nematode of the genus Trichocephalus Schrank, 1788, family Trichocephalidae, Baird, 1853 – whipworm Trichocephalus trichiurus. The generic name of the helminth consists of two Greek words: thrix – hair, Kephale – head (hairy head), which reflects the shape of the body of the helminth. In the Russian medical literature of previous years, it can be found under the name – whipworm.
Whipworms are thin nematodes, the front end of the body, which is about 2/3 of the length, is threadlikely elongated, and the rear end is short and thick. In females, the back end is in the form of a saber-curved arc, in the male; spirally twisted.
The length of the male is 3–4.5 cm, the females are 3.5–5.5 cm. During life, the body of the helminth is white, sometimes grayish-reddish, the cuticle is transversely striated. The digestive system is represented by the mouth opening, deprived of the lips, which leads to a long and thin esophagus, on the front surface of which the digestive glands are arranged in one row, so that the esophagus looks clear. At the junction of the anterior thin part of the body, vlasgoglu into the thickened esophagus passes into the intestinal tube, ending with the anus on its posterior end.
The female reproductive system has an unpaired genital opening on the border of the filament-like front end to the thickened back. In the male, the reproductive system is also unpaired and ends with a curved and pointed spicule (2.5 mm) which is located in the spinal vagina, covered with numerous spines.
Whisker eggs are yellowish-brown or golden-yellow in color, barrel-shaped (lemon-shaped), have colorless “corks” at the poles). These corky formations are protrusions of the inner shell. The egg shell is smooth, thick consists of four shells. The inner fibrous casing serves to protect the eggs from chemical damage, the rest from mechanical ones. The eggs are 47–54 µm long and 22–23 µm wide.
Eggs from the uterus of the female come out before the start of crushing, the internal content of their fine-grained, their further development and maturation is completed in the external environment.
Whipworms are parasitic in humans, some species of monkeys. The habitat of sexually mature worms are: cecum, vermiform process, the descending part of the colon. With intensive invasion, they inhabit all parts of the colon and in the lower segment of the small intestine. The front end of the whipworm penetrates the mucous, submucous and muscular membranes of the intestinal wall, its posterior end hangs loosely in the intestinal lumen.
The helminth feeds at the expense of tissue juice, less by blood (it is an optional hematophagus), which, according to the laws of a capillary vessel, enters its thin esophagus. Fertilized females lay in the lumen of the intestine per day from 1000 to 3500 immature eggs. Their development to the stage of invasive larva occurs in the environment in the presence of oxygen, sufficient humidity and temperature. The larva matured in the mature egg has a spear-shaped stylet – a morphological indicator of invasiveness. In the external environment, eggs remain viable and invasive for 1-2 years, in temperate climates they can winter through under a thick layer of snow.
T. trichiurus parasitizes only in a person who becomes infected when swallowing invasive eggs that have matured in the soil. In the small intestine, the shell of the egg is destroyed, the larva leaves it, which with the help of the stylet penetrates into the deep layer of the mucous membrane, develops there within 3-10 days, after which it goes into the lumen, goes down into the cecum, where in about 1.5 months it reaches mature state.
The life span of the parasite in humans is 5-7 years.
Pathogenesis during Trichocephalosis (Trichurosis)
In the epidemiology of trichocephalosis and ascariasis, the dose has much in common.
Trichocephalosis, as well as ascariasis – natural-endemic invasion, geohelminthiasis and the only source of invasion is man. The main factors of pathogen transmission are vegetables, berries, table greens, consumed by a person without heat treatment. Infection can occur through contaminated hands.
The most favorable conditions for the development of eggs are created in the soil at a temperature of + 26 ° C to + 30 ° C, relative air humidity close to 100%, soil moisture 18 – 22%. Under these optimal conditions, eggs become invasive in 17 to 25 days. However, eggs in the external environment can develop in the temperature range of +15 – + 35 ° С, and the period of their development varies from two weeks to 3-4 months.
At the same time, there are some peculiarities in the epidemiology of trichuriasis compared with ascariasis, due to the biology of the pathogen. In particular, with trichocephalosis, the pathogen is parasitic in the human body for up to 5 years (for 1 year of ascariasis), i.e., the source of invasion pollutes the soil for a longer period and there is no seasonality in the incidence of trichocephalosis. The development of slag eggs occurs at a higher soil moisture content in the range of 18–22%. Under favorable conditions, whipworm eggs remain viable in the soil from 10 to 36 months.
They can develop in the environment at a higher temperature and atmospheric humidity (not less than 85%), the development period of the larvae is longer, the resistance of eggs to ultraviolet rays and to drying, to the influence of high and low temperatures is higher. Therefore, although the distribution of ascariasis and trichocephalosis coincides in general terms, the distribution range of trichocephalosis is somewhat shifted to the south.
In a warm and humid climate, trichocephalosis is possible throughout the year, and the mass infection season lasts 5.5–6 months from the end of March to the first decade of October.
As with ascariasis, trichocephalosis is more common in children, as well as among those who work with the land, fertilizing the land with non-disposed feces, among sewer workers and sewage treatment plants, cesspool workers, field farmers, gardeners, etc.
The pathogenic effect of whipworms on the body consists mainly of mechanical and allergic effects.
Being introduced into the intestinal wall, the whipworm with its thin hair-like head end “flushes” the mucous membrane as it were, penetrating sometimes to the submucosal and muscular layers. In places of localization of the parasite, infiltrates, small hemorrhages, edemas, erosion occur around the sites of the head end implantation on the mucous membrane. Changes and trauma to the intestinal wall, which depend on the intensity of invasion, contribute to the penetration of the microbial flora. As early as 1901, I. I. Mechnikov pointed to the significant role of claws in the development of appendicitis and typhlitis.
A certain value in the pathogenesis of trichocephalosis has a sensitizing effect of metabolic products on the body. We must assume that it is precisely this that aggravates the effect of bacterial flora on the colon mucosa, which is clinically manifested by the tendency of such patients to diarrhea, as well as to neurological disorders.
An important role in the pathogenesis of trichocephalosis are visceral reflexes that bind the ileocecal region (the place of localization of whipworms) with other areas of the intestine. Irritation of the nerve endings of the ileocecal region entails a violation of the secretory and motor function of the stomach. This explains the frequent violations of gastric secretion, the appearance of pain in the epigastric region, simulating gastric ulcer and duodenal ulcer.
Whipworms are facultative hematophagous, each helminth is able to absorb per day up to 0.005 ml of blood. With very intense invasions that are registered in tropical regions of the world (up to 5,000 parasitic individuals), anemia is described in children.
Symptoms of Trichocephalosis (Trichurosis)
The clinical picture of trichocephalosis is diverse and depends on the intensity of invasion, the reactivity of the organism and the presence of concomitant diseases.
In nonintense invasion, trichocephalosis proceeds subclinically. In clinically significant forms, symptoms of pathology of the gastrointestinal tract and the nervous system are usually observed, but there is no pathology characteristic of this invasion only in trichocephalosis.
Disorders of the gastrointestinal tract are manifested in decreased appetite, nausea, vomiting, drooling. Patients note pains in the right ileocecal region, resembling appendicitis pain, pains of a cramping character in the epigastric region, simulating the clinic of gastritis, peptic ulcer. Sometimes with trichocephalosis, a pattern of colitis with diarrhea or constipation develops in the infested, less often with the presence of visible mucus and blood in the feces. With trichocephalosis, there may be complaints of headache, dizziness, irritability, poor sleep, less often – fainting, convulsive seizures.
Diagnosis of Trichocephalosis (Trichurosis)
The diagnosis is established on the basis of detection in the feces of eggs when viewing large smears under the binocular, as well as flotation methods with the study of the surface film under the binocular directly in the cup or after removing it with a glass slide. In view of the fact that a significant part of the infected invasion intensity is weak, the eggs in the feces are often small and difficult to detect. Therefore, careful and repeated research is needed. Records of the results of treatment is carried out by controlling the study of feces 15-20 days after deworming.
Treatment of Trichocephalosis (Trichurosis)
The drug of choice is mebendazole (vermox). Adult dose 100 mg 2 times a day, a course of 3 days. Effective with trichocephalosis Quantrell (daily dose of 10-20 mg / kg once, course of 2-3 days), diphaseal (daily dose for children under 5 years old – 2.5 g, older than 5 years and adults – 5 g, given once, course 5 days). If necessary, the course of treatment of trichocephalosis is repeated after 2-3 weeks.
The treatment of trichocephalosis is only subjected to invasions the rest of the family members conduct a threefold coproovoscopic examination. Recommend disfim, bemosat, vermox (according to generally accepted schemes). To determine the effectiveness of treatment, the clinical diagnostic laboratory of a medical institution that has identified an invasion and who has treated it, conducts a threefold examination (with an interval of 15-20 days). Clinical examination of the invasive and his family is carried out within 2 years after the moment of treatment. During this time, in spring and autumn, all family members are examined for helminthiasis, and the sanitary-epidemiological service at the same time carries out a selective epidemiological survey of microcoots with a helminthological study of environmental elements.
The microfocal is removed from the register, if within 2 years from the moment of treatment of the invasive one, not a single case of trichocephalosis has been registered, the false microfocal is after a threefold negative result of the examination according to the Kalantaryan method since the end of treatment. In the case of the establishment of a permanent link between the false and true microfocal, recovery is carried out in both at the same time, and the period of clinical examination in them in this case is 2 years.
Prevention of Trichocephalosis (Trichurosis)
The complex of preventive measures for trichocephalosis is similar to that for ascariasis and is carried out simultaneously. The most important are measures aimed at protecting the soil from fecal contamination and increasing the sanitary literacy of the population.