There is an extensive body of medical and scientific research literature on visceral leishmaniasis (VL) in the Caucasus, Central Asia, the Crimean Peninsula and the southern part of The Russian Federation that is written in Russian, making it inaccessible to the majority of people who are interested in the leishmaniases in general and VL in particular. This review and summary in English of VL in what was Imperial Russia, which then became the Soviet Union and later a number of different independent states intends to give access to that majority. There are numerous publications in Russian on VL and, mostly, those published in books and the main scientific journals have been included here. The vast geographical area encompassed has been subdivided into four main parts: the southern Caucasus, covering Armenia, Azerbaijan and Georgia; Central Asia, covering Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan and Uzbekistan; the Crimean Peninsula and the northern Caucasus, which is part of The Russian Federation. Only rare cases of VL have been recorded in the northern Caucasus and Crimean Peninsula. In the other countries mentioned, human VL has been more intense but epidemics like those associated with L. donovani in India and East Africa have not occurred. For most of the countries, there are sections on the distribution, clinical aspects, the causative agent, the reservoirs and the vectors. Serological surveys and research into therapy are also covered. Recent studies on VL in Uzbekistan covered the application of serological, biochemical and molecular biological methods to diagnose human and canine VL, to identify the leishmanial parasites causing them in Uzbekistan and neighbouring Tajikistan and the epidemiology of VL in the Namangan Region of the Pap District, Eastern Uzbekistan. More recently, two studies were carried out in Georgia investigating the prevalence of human and canine VL, and the species composition of phlebotomine sand flies and their rates of infection with what was probably L. infantum in Tbilisi, eastern Georgia and Kutaisi, a new focus, in western Georgia. Though published in English, summaries of this information have been included where relevant to update the parts on VL in Uzbekistan and Georgia.

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The process of production of inactivated influenza vaccines involves a stage of inactivation of both the influenza virus and the possible viral contaminants that can come from the raw materials (chicken embryos). One of such contaminants is the avian leukemia virus. The minimum viral contaminant load reduction that the inactivating agents should guarantee is by 4 lg/ml; this or higher level of the deactivating ability ensures the finished vaccine is free from viral contaminants. The purpose of this work was to cultivate the leukemia virus to the titer of 5 lg/ml (minimum) and to measure the reduction of the avian leukemia virus titer in influenza vaccine intermediates upon exposure to the inactivating agents. The RAV-1 and RAV-2 leukemia virus strains and influenza vaccine intermediates such as virus-containing allantoic fluid and virus concentrates were used in the study. Avian leukemia virus titers were determined by enzyme immunoassay. We created conditions for cultivation of the RAV-1 and RAV-2 avian leukemia virus strains in the primary culture of chicken embryo fibroblasts (CEF); the inactivating agents considered were the most commonly used β-propiolactone and UV radiation. It was found that after 12 hours of exposure to β-propiolactone, the RAV-1 avian leukemia virus load decreased by 4.61 ± 0.46 lg, and that of RAV-2 strain - by 4.33 ± 0.33 lg, which indicates that β-propiolactone is an effective inactivating agent. Five minutes of exposure to UV radiation reduces the RAV-1 strain viral load by 4.22 ± 0.31 lg and RAV-2 strain viral load by 4.44 ± 0.48 lg.

The programs carried out previously for the eradication of infectious diseases have been described with the special attention in regard to the reasons of its failures and/or negative experience gained. So far the global program on smallpox eradication achieved the established goal, while two other, polio eradication initiative and dracontiasis eradication, are still going on rather long period of time. The program of elimination of measles and rubella, which according to the original plan, should be movedfor eradication in the future, is facing a lot ofproblems for the time being and therefore it is difficult to predict any future developments in this area. Nevertheless a number of initiatives and/or programs are very much keen nowadays to establish the goal of eradication or elimination without, according the authors opinion, serious and deep analysis of the burden of the targeted disease, its epidemiological and clinical peculiarities, feasibility for achievement of goal etc. The criterions for the disease selection for eradication/elimination are presented in the article. The hasty decision on such matter may lead to the failure of initiative, lack of the staff motivation, loss of the public health authority prestige and discredit the disease eradication concept as such.

Introduction. Arboviral infections are a rising public health concern not only for some individual countries, but also for the entire world due to the repeated outbreaks over the past decade.The aim was to conduct a seroprevalence study of Dengue (DENV), Zika (ZIKV), Yellow fever (YFV) and Chikungunya (CHIKV) viruses using a limited number of samples in Nicaragua.Materials and methods. Total 200 serum samples collected previously in Nicaragua were analyzed simultaneously. Commercially available diagnostic kits, as well as in-house methods were used. The avidity of antibodies (IgG) in positive serum samples was assessed after the treatment with 8M urea.Results. 85 serum samples (42.5%) contained IgG antibodies to one or several viruses simultaneously. IgG antibodies only to one virus were detected in 46 serum samples (23%) with the avidity index (AI) ≥ 30%. Among 39 samples (19.5%) that contained IgG antibodies to several viruses, only in 19 samples (9.5%) IgG antibodies with high AI (≥ 30%) to several viruses were detected. In 16 serum samples (8.0%), IgG antibodies to DENV with a high AI and antibodies to ZIKV and/or YFV with a low AI < 30% were detected.Discussion. The results obtained in ELISA testing were corrected, since only IgG antibodies with a high AI confirm the past infection. The analysis of the specific IgG antibody avidity helped not only to confirm the cases of combined or sequential infection in the past, but also to discriminate the cross-reactive IgG antibodies induced by closely related DENV, ZIKV and YFV. The presence of cross-reactive IgG antibodies, on the one hand, make it difficult to determine the real seroprevalence of flavivirus infections, and, on the other hand, may increase the risk of antibody-dependent enhancement (ADE) of the disease, which is well-known for the secondary Dengue fever and for the consecutive infection with DENV and ZIKV.Conclusion. The analysis of virus-specific antibody avidity made it possible not only to distinguish recent from the past infection, but also to discriminate the cross-reactive antibodies with the low avidity.