The dissertation is devoted to finding out the features of clinical course of giardiasis in adults with comparison of the effectiveness of different methods of laboratory examination during the initial visit of patients with giardiasis, which made it possible to optimize the diagnostics, to develop a diagnostic algorithm and to correct the revealed disorders. To achieve the objectives 164 people were examined (74 men and 90 women) aged 20 to 60 years old and 20 quiet healthy individuals of similar age and gender who were treated at the Department of Medical Parasitology and Tropical Diseases in 2012-2017 years, and underwent comprehensive clinical laboratory and instrumental examination. The work analyzes the data of a carefully collected anamnesis, subjective and objective data, defines the clinical and laboratory features of the course of giardiasis in patients, presents data on the state of nonspecific immune protection with the definition of a set of indicators that characterize cellular and humoral immunity. When conducting a clinical and statistical analysis of the effectiveness of different multiplicities of coproprotozooscopic studies, it was found that for the verification of giardiasis the most optimal from a clinical point of view is the threefold coproprotozooscopic study. The increase in the number of patients with identified lamblia cysts was 25,6% (p <0,001) during the transition from one- to a two-fold study, and 18,3% (p <0,001) during the transition from two- to three-fold studies. The increase in the number of individuals with isolated lamblia cysts in the fourth and fifth analyses turned out to be statistically insignificant, amounting to 1,2% and 0,6%, respectively (p >0,05 and p >0,05, respectively). Based on the results of long-term follow-up observation of patients with giardiasis, an algorithm for laboratory examination and treatment monitoring was developed. According to the results of long-term follow-up observation of patients with giardiasis, we have developed an algorithm for laboratory examination and treatment monitoring, taking into account the fact that at the present stage practical doctors in screening diagnostics of infectious and parasitic diseases prefer immunological methods. ELISA was used as the starting laboratory test to determine the concentration of specific IgG antibodies. Regardless of the results of ELISA, the next stage of the examination was clinical diagnostics, which allowed us to outline a further strategy for laboratory examination of the patient. Conducted clinical and statistical study of various regimens of etiotropic treatment of giardiasis based on the principles of evidence-based medicine showed that etiotropic drugs (furazolidone, ornidazole, metronidazole, albendazole) have the same antiparasitic and clinical efficacy. As comparative studies have shown, the elimination of the parasite has been achieved in more than 90% of treated patients with giardiasis.
