What is Intestinal Capillaria?
Intestinal capillarosis is a helminthiase in humans caused by the nematodes Capillaria philippiensis. Capillaries were first discovered in 1963 in a seriously ill patient in the Philippines. Invasion is manifested in intractable diarrhea with a high mortality rate. A clinical study showed the presence of severe enteropathy with protein loss and impaired absorption of fats and carbohydrates.
Causes of Intestinal Capillaria
Capillaries are nematodes of the Trichuroidea family, Capillaria philippinensis, and are very close to the representatives of the same group of helminths – whipworm and trichinella. Adult capillaries are small parasites from 2 to 4 mm long. Eggs are peanut-shaped with flat bipolar plugs; their sizes are on average 42–20 µm. Adult parasites live in the mucous membrane of the small intestine, especially often in the jejunum. Adult worms, larval forms, and eggs are found in the feces.
The invasive person is not contagious. The natural susceptibility of people seems to be high. The incubation period lasts a month or more.
The disease was found almost exclusively in individuals living along the north and west coast of Luzon Island, the Philippines. It was also reported on several cases in Thailand. Since 1966, the disease has taken the form of an epidemic, and more than 2,000 cases and 100 deaths have been reported. Men were more likely to become infected than women, perhaps because of their vocational training. Before the discovery of effective chemotherapeutic drugs, the death rate in the absence of treatment reached 30%; with the introduction of chemotherapy, it was reduced to 6%.
The mode of transmission and the life cycle of the helminth are not fully understood. Larvae of the I stage of development were found in some species of freshwater fish. When these fish or larvae are eaten by gerbils, helminths develop into an adult state in the intestinal lumen. Adults quickly begin to produce new larvae that mature to adult parasites of the second generation. Most of the females of this generation produce eggs, the latter fall into the gerbil feces. Some females, however, hatch larvae, which leads to the emergence of another generation of adult parasites in the intestine. Eggs should apparently mature in fresh water before they are swallowed by fish. Natural infection of others. mammals other than humans have not been established, however, birds and rats may be infected experimentally. The presence of a large number of adult worms, larva-bearing females, developed eggs and all larval stages in the human intestine allows us to conclude that the parasitic cycle in gerbils and humans is the same. The mechanisms by which people are infected remain unspecified. However, it is known that many naturally infected lagoon fish, in particular Hypselotris bipartita, are consumed raw by the people of Luzon.
Pathogenesis during Intestinal Capillaria
Adult worms in large numbers penetrate the mucous membrane of the small intestine and cause severe enteropathy with protein loss and impaired absorption. As a rule, hypokalemia, hypocalcemia and hypoproteinemia are noted. According to the autopsy, the invasion does not extend beyond the intestine.
Symptoms of Intestinal Capillaria
At the beginning of the disease, rumbling in the abdomen and recurrent, vague abdominal pains appear, then, usually after 2-3 weeks, profuse watery diarrhea begins. Other symptoms that correspond to the main pathophysiological processes are lack of appetite, vomiting, weight loss, muscle atrophy and weakness, hyporeflexia and edema. There may be pain and tension in the abdomen. The period between the onset of symptoms and the death of the patient usually lasts for 2-3 months. Subclinical invasion was not observed.
Diagnosis of Intestinal Capillaria
The diagnosis is based on the detection of eggs in the feces. Capillary eggs should be differentiated from clawed eggs similar to them. It is necessary to take measures in order not to miss capillariasis in persons with trichuriasis, since in the endemic zone in the majority of patients both of these invasions can coexist.
Treatment of Intestinal Capillaria
The use of mebendazole is combined with the introduction of fluids and electrolytes, which leads to an improvement in the patient’s condition: 400 mg of the drug per day, divided into several doses, should be prescribed for 20 days to prevent relapse.