Cryptosporidiosis is a disease caused by unicellular parasites belonging to the Cryptosporidium genus. The small intestine is the primary site of localization of infection which predicts the main clinical symptom of the disease — diarrhea. The most important factors influencing Cryptosporidium infection and the course of disease are molecular genetic variability of the parasite, its virulence and infectivity, and viability of the mucosa of the digestive tract and local and systemic immunity of the macroorganism. The immune status of the host plays a key role in determining sensitivity to infection and the severity of the disease. Cryptosporidium infection differs in outcomes: asymptomatic in some patients, acute enteritis accompanied by profuse diarrhea, lesions of internal organs, and fatal outcome in others. Current therapeutic approaches to the treatment of cryptosporidiosis are ineffective. Despite the existence of a large number of drugs with antiparasitic effect, there are no medications with a specific effect on cryptosporidia. Understanding the factors that determine both the pathogenicity of Cryptosporidia and the protective properties of host defense systems will allow developing effective prevention measures and therapeutic interventions of this protozoosis.
Background. Cryptosporidium protozoa are the leading causative agent of diarrhea and cause of death in children under 5 years of age. The role of cryptosporidia in the development and course of acute intestinal infections (AII) in children in Russia remains unstudied. Objective. Our aim was to study the prevalence and clinical laboratory features of cryptosporidium-associated aII in children under 5 years of age. Methods. A cross-sectional study (conducted in March-June 2017) included children admitted to hospital with symptoms of AII (fever, loose watery stools, weakness, decreased appetite and/or vomiting) by the ambulance service. On admission, stool samples were collected from all patients. Cryptosporidium oocysts were determined by microscopic examination of faecal smears stained according to Tsil-Nielsen after preliminary concentration by a modified formalin-ether technique. The presence of intestinal pathogens was determined by a bacteriological technique and using a polymerase chain reaction. Results. The study included 107 children with AII (girls — 51%). Cryptosporidia were detected in 28 (26%) patients, in 93% of cases — together with bacterial and/or viral pathogens. The etiological structure of cryptosporidium-associated AII and AII in cryptosporidiosis negative children (n = 79) did not differ. On admission, children with cryptosporidium-associated AII had a higher blood leukocyte count — 13.0_109/L (9.2; 16.0) versus 8.3_109/L (6.1; 11.2) in children without cryptosporidiosis (p < 0.001). It has been also found that antibiotics were more often used in the treatment of children with cryptosporidium-associated AII — in 21 (75%) versus 39 (49%) in the comparison group (p = 0.026). Conclusion. Cryptosporidia are detected in every fourth child with AII under 5 years of age. Patients with cryptosporidia are distinguished by a higher level of blood leukocytes upon admission and a more frequent prescription of antibiotics than in the group of cryptosporidiosis negative patients.
The aim of this study was to identify the features of CD4+ lymphocytes apoptosis in children with cryptosporidiosis. Feces for the detection of cryptosporidium and venous blood for the study of lymphocytes apoptosis were the material of the study. Mononuclear leukocytes were isolated from venous whole blood and cultured in a complete culture medium. Cells were incubated for 24 hours with inducers of the receptor (TNFα) and mitochondrial pathways of apoptosis (dexamethasone).Cryptosporidia have been found in 35% of acute intestinal infections in children. The number of lymphocytes with cytoflurimetric signs of apoptosis in the group of cryptosporidiosis-positive patients did not differ from that in patients without cryptosporidiosis (p=0.421). There were no intergroup differences in the number of CD4+ lymphocytes expressing the Fas receptor on their surface (p=0.462). In cultures incubated in the presence of dexamethasone, a decrease in the number of apoptotically altered CD4+ lymphocytes was registered only in the group of cryptosporidiosispositive patients (p=0.028).The study showed that in cryptosporidiosis, the sensitivity of CD4+ cells to the induction of the mitochondrial pathway of apoptosis changes in favor of slowing down this variant of cell death.
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