Cryptosporidiosis

Cryptosporidiosis - protozoal disease, usually occurring in the gastrointestinal form of diarrhea osmotic type and cause severe illness in persons with immunodeficiency.

New Cryptosporidium were detected in 1907 E. Tyzzer in the gastric mucosa in laboratory mice with no signs of pathology of the gastrointestinal tract. This organism is considered "harmless" commensal for over 50 years. In 1955 was registered the first case of cryptosporidiosis in animals - Cryptosporidium were identified in fatal gastroenteritis in poultry. Since 1970, Cryptosporidium was found in the gastrointestinal tract (GIT) and / or respiratory tract of most mammals, birds, fish and reptiles.

The first case of cryptosporidiosis in humans is described in 1976, and in the early 1980's, it became clear that the genus Cryptosporidium frequently cause infections in humans, which is associated not only with the improvement of diagnosis, but also a significant increase in the number of persons with immunodeficiency primarily with the acquired immunodeficiency syndrome (AIDS).

What provokes Cryptosporidiosis?

The genus Cryptosporidium (from the Greek. Implicit argument) belongs to the family Cryptosporidiidae, subtype Apicomplexa (due to the fact that sporozoites are apical complexes), class Sporozoasida, subclass Coccidiasina.

Cryptosporidium are obligate parasites, infecting mucous membranes of the microvilli gastrointestinal and respiratory tracts of animals and humans. Initially it was thought that different Cryptosporidium strictly specific to the particular type of vertebrate or person in connection with which their classification has been constructed on the basis of infected animals. However, further experiments on cross-infection have shown that various Cryptosporidium is much less specific than previously thought.

In this regard, in 1984, pre-existing species (21 species) were grouped into 4 types. Currently genus Cryptosporidium officially includes 6 species: C. nasorum, infecting fish, C. serpentis, infecting reptiles, C. baileyi and C. meleagrides, infect birds, C. muris and C. parvum, infect mammals. It should be emphasized that virtually all cases of cryptosporidiosis were caused by human C. parvum.

The cycle of Cryptosporidium is "exclusive", ie all cycles of development occur in the body of the same host.

Epidemiology. Infections of the gastrointestinal tract caused by cryptosporidium, are registered in all age groups and on all continents except Antarctica. Such wide distribution of cryptosporidiosis associated with a large number of natural reservoirs of infection, low infective dose and high-resistant pathogens to disinfectants and antiparasitic drugs. Children, especially under the age of 2 years, more susceptible than adults. Cumulative incidence of cryptosporidiosis is about 1-3% in industrialized countries and 5-10% - in developing countries.

It should be noted that gipodiagnostiks this disease is associated with the imperfection of diagnostic techniques and the need for a special color samples, which is held not in all laboratories. The results of serological studies suggest that perhaps, cryptosporidiosis occurs much more frequently than is diagnosed. Thus, antibodies to cryptosporidium were detected in 25-35% of persons in the populations of industrialized countries and in about 65% - in developing countries.

Some authors note that for cryptosporidiosis is characterized by some seasonality with peak incidence in the warm season. Human infection occurs by ingestion of oocysts, mainly at the use of water. Preserving the Environment, Cryptosporidium oocysts are capable of infection by up to 18 months at 4 °C and up to 1 week at minus 10 °C. However, when heated (72 °C) die within 1 min.

The main mechanism of transmission - fecal-oral. Infection can occur through direct contact with an infected person or animal, as well as environmental objects (usually with water), contaminated cryptosporidium.

Infective dose of Cryptosporidium is very small. Thus, the experiment showed that the development of infection in primates can occur even when hit 10 oocysts. In healthy volunteers clinical cryptosporidiosis developed in 100% of cases by ingestion of oocysts and in 1000 20% - by ingestion of oocysts 30. The mathematical modeling showed that the infection can cause a hit in the gastrointestinal tract even a single oocyst, while 50% infective dose - approximately 132 oocysts.

Waterway spread of cryptosporidiosis, first described in 1983, is the main mode of the parasite. The greatest danger lies in the fact that most modern technology does not allow to purify water from Cryptosporidium. This is due to the unique resistance of oocysts to disinfectants, especially chlorine, as well as the small size of oocysts, allowing them to pass through many filters.

The period of infectiousness of the source - the entire period of the disease and several weeks after the disappearance of clinical symptoms.

Pathogenesis during cryptosporidiosis.

After ekstsistirovaniya oocysts caught up in the stomach and duodenum, sporozoites are released from reaching the microvilli of enterocytes, where there is a further development of them formed trophozoites. Parasite invaginating the apical membrane at the base of microvilli, which, stretching and slip over it, form a parasitophorous vacuole. With further propagation of Cryptosporidium actively contaminating small intestinal mucosa and damage it mikrovorsinchatuyu rim. This results in a violation of membrane digestion and absorption - maldigestion and malabsorption. Excessive amounts of disaccharides, peptones and other non-fermented completely substances in the lumen of the small intestine, promotes osmotic gipofermentativnoy diarrhea. This diarrheal syndrome is maintained and further strengthened the emerging fermentative dyspepsia. The latter develops as a result of income in the cecum of a large quantity of unfermented disaccharides.

Accession vomiting increases the loss of fluid and electrolytes. In some cases, the disease may occur without diarrhea, because of damage cryptosporidium gastric mucosa.

When cryptosporidiosis may be affected epithelium of the pharynx, larynx, esophagus, stomach, but most often damaged epithelium of the small intestine. Against the background of immunodeficiency there is a severe form of the disease, in addition to the digestive system in the pathological process involved other organs and tissues.

Symptoms of cryptosporidiosis?

The incubation period lasts from 4 to 14 days.

The spectrum of clinical manifestations of cryptosporidiosis is quite wide. First of all, it depends on the immunological status of the patient. The main and most common clinical manifestation of disease as patients with normal immune systems, and with immunodeficiency is profusely watery diarrhea.

In patients with normal immune systems develop diarrhea, usually acute, lasts from several days to 2 weeks, after which always takes place independently. In contrast, in patients with AIDS diarrhea develops progressively more severe (average 3-6 liters per day, less often - up to 20 liters per day) may continue for several months and often leads to life-threatening patient's dehydration and electrolyte disturbances. Very rarely when cryptosporidiosis subfebrile marked increase in body temperature and flu-like syndrome - myalgia, headache, weakness, anorexia.

While patients with normal immune systems, symptoms of cryptosporidiosis is limited only by diarrhea, then the immunodeficiency can be observed both intestinal and extraintestinal symptoms associated with damage to the respiratory tract, pancreas and biliary tract.

Respiratory infection is accompanied by a cough, shortness of breath and wheezing, hoarseness. This patient is not necessarily a defeat of the intestine.

Cryptosporidiosis biliary cholecystitis can occur much more rarely - hepatitis and sclerosing cholangitis, which clinically manifested by fever, pain in right hypochondrium, jaundice, nausea, vomiting and diarrhea. Can increase the level of bilirubin, alkaline phosphatase and transaminases. Diagnosis of biliary cryptosporidiosis is based on biopsy and detection of different developmental stages of Cryptosporidium in the biliary tract. The defeat of cryptosporidium pancreas is extremely rare. Described only 8 cases in HIV-infected patients.

Bronchopulmonary (respiratory), cryptosporidiosis is characterized by fever, lymphadenopathy, prolonged cough with scanty mucous, less mucous-purulent sputum, dyspnea, cyanosis. In sputum can be detected Cryptosporidium oocysts. When a biopsy revealed metaplasia of surface epithelial cells of bronchi. Patients with AIDS are described and bilateral interstitial pneumonia caused by cryptosporidium. Oocysts while detected in alveolar macrophages. Respiratory cryptosporidiosis completed death of patients, despite massive chemotherapy.

Diagnosis of cryptosporidiosis?

Diagnosis of cryptosporidiosis in most cases based on the detection of Cryptosporidium oocysts in the faeces and (or) much less frequently - in the biopsy of small intestinal mucosa in the syndrome of watery diarrhea. However, the most commonly used conventional staining methods, in most cases do not allow a diagnosis as Cryptosporidium or stained very weakly, as, for example, when stained by Gram or painted so that they can not distinguish from yeasts.

In this regard, the majority of authors consider a modified (as dekolorayzera spirtoatsetonovoy mixture is used instead of 1% sulfuric acid) color for acid-optimal for visualization of Cryptosporidium. With this method, staining Cryptosporidium oocysts are stained in red (or pink) color and clearly visible on the blue-violet background, which are painted other microorganisms and the contents of the intestine. Currently available as monoclonal antibodies labeled with a fluorescent label, which also allows you to visualize this microorganism with high specificity and sensitivity.

In acute cryptosporidiosis number of oocysts in the feces large. This allows the use of direct microscopy sample of feces. However, in some situations, such as chronic cryptosporidiosis with mild, when the concentration of oocysts in feces is small, it is necessary to use special techniques to increase their concentration. These include methods of flotation (in sucrose solutions for Sheaher, zinc sulfate, saturated solution of sodium chloride) and methods of concentration (formalin-ethyl acetate and efirformalinovy).

Developed serological tests - immunofluoresence and ELISA. However, their importance for the diagnosis of active disease is very limited and little. In this regard, the tests are only used in epidemiological studies.

Some authors recommend the use of molecular methods, particularly polymerase chain reaction (PCR). However, their importance for routine laboratory diagnosis of cryptosporidiosis is not yet defined.

Treatment of cryptosporidiosis?

Cryptosporidiosis is not subject to treatment. However, antiretroviral drugs may reduce or stop the symptoms of this disease.

Several drugs that are intended for other purposes, are being tested for treatment of cryptosporidiosis. They include Paromomycin (Humatin), azithromycin (Zithromax), Latrazuril and Atovaquone (Mepron).

But the most promising drug in this area is nitazoxadin. He has helped half of all patients who participated in the research of this drug. Unfortunately, the development nitazoksadina was stopped in connection with the decision of the Office of the Food and Drug Administration. However, in 2002 the drug was approved for the treatment of children.

From crypto-infection can not get rid. But there is a possibility to control diarrhea caused by this infection. You can use Imodium, Kaopektat and other similar drugs. In severe cases of diarrhea are also sometimes treated with Sandostatin.

Another drug to fight diarrhea caused by cryptosporidiosis, Sporidin-G, is now under testing.

If you have diarrhea, turn your attention to the fact that you should drink plenty of fluids to avoid dehydration.

There shall be carefully selected (with the lack disaharov) diet, enzymes, mukoprotektory. In immunocompetent persons etiotropic therapy using macrolides, cotrimoxazole, daraprim, metronidazole, furazolidone. A rehydration therapy.

Effective methods of therapy etiotropic immunocompromised persons, and, especially, HIV / AIDS patients has not yet been developed. Attraction using macrolides, clindamycin, furazolidone and other drugs. However, the main importance is the pathogenetic therapy and more effective treatment for major diseases - HIV infection. Nevertheless, in patients with immunodeficiency diseases of any nature encourages the use of spiramycin (rovamicyn) to 3-9 grams per day.

Prevention of cryptosporidiosis.

Medicines to prevent cryptosporidiosis does not exist.

The best protection - it is clean. Avoid contact with the feces of people or animals. Be sure to wash your hands after using the toilet, gardening, handling dirty laundry or animals, or child care (diapering). Cryptosporidiosis can be transmitted through saliva or sexual contact. Do not swallow water while swimming, because it may contain bacteria cryptosporidiosis. Raw oysters may also contain these bacteria.

In some cities, public water supply may carry bacteria cryptosporidiosis. This can be found in the department of water supply in your city. If drinking water contains bacteria, and your number of CD4 cells below 300, try to fulfill the following conditions:

• Bring drinking water to a boil and boil for at least 1 minute, or
• Drink bottled water, or
• Drink filtered water. Use the filters that are marked with the inscription "1-micron filter" or "complies with the National Science Foundation", or
• Drink distilled water as bottled water may be unsafe if it had not been brought to a boil or cleaned properly.