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New geographical area on the map of Crimean-Congo hemorrhagic fever virus: First serological evidence in the Hungarian population

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Abstract

Crimean-Congo hemorrhagic fever (CCHF) is an emerging tick-borne disease that is endemic in Africa, Asia, the Middle East, and the Balkan region of Europe; the disease is spreading northwards following widespread distribution of the main vector, Hyalomma marginatum, which was first found in Hungary in 2011. The aim of this pilot sero-surveillance study was to assess CCHF seroprevalence in Hungary. A total of 2700 serum samples obtained from healthy volunteer blood donors were screened using an in-house immunofluorescence assay and a commercially available ELISA kit. We found ten (0.37 %) seropositive donors. The western and central regions proved to be the most affected areas, with a prevalence of 2.97 %. Higher positivity was found among male donors (0.55 %) and younger donors (18–34 years; 0.78 %). Based on these results, a more extended surveillance focusing on specific at-risk populations and animals is advised. The results should also raise the awareness of clinicians and other high-risk populations, such as foresters and hunters, about the emerging threat of CCHF in Hungary.

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... In Bulgaria and Hungary, countries that are on the border with Romania, CCHFV is endemic, which suggests that the virus could also circulate in Romania. Small ruminants have been recognized as CCHFV hosts in certain endemic regions and have been epidemiologically linked to human cases (Gergova and Kamarinchev 2013, Földes et al. 2019, Magyar et al. 2021. ...
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Outbreaks that occur as a result of zoonotic spillover from an animal reservoir continue to highlight the importance of studying the disease interface between species. One Health approaches recognise the interdependence of human and animal health and the environmental interplay. Improving the understanding and prevention of zoonotic diseases may be achieved through greater consideration of these relationships, potentially leading to better health outcomes across species. In this review, special emphasis is given on the emerging and outbreak pathogen Crimean-Congo Haemorrhagic Fever virus (CCHFV) that can cause severe disease in humans. We discuss the efforts undertaken to better understand CCHF and the importance of integrating veterinary and human research for this pathogen. Furthermore, we consider the use of closely related nairoviruses to model human disease caused by CCHFV. We discuss intervention approaches with potential application for managing CCHFV spread, and how this concept may benefit both animal and human health.
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Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne infection caused by a virus (CCHFV) from the Bunyaviridae family. Domestic and wild vertebrates are asymptomatic reservoirs for the virus, putting animal handlers, slaughter-house workers and agricultural labourers at highest risk in endemic areas, with secondary transmission possible through contact with infected blood and other bodily fluids. Human infection is characterised by severe symptoms that often result in death. While it is known that CCHFV transmission is limited to Africa, Asia and Europe, definitive global extents and risk patterns within these limits have not been well described. We used an exhaustive database of human CCHF occurrence records and a niche modelling framework to map the global distribution of risk for human CCHF occurrence. A greater proportion of shrub or grass land cover was the most important contributor to our model, which predicts highest levels of risk around the Black Sea, Turkey, and some parts of central Asia. Sub-Saharan Africa shows more focalized areas of risk throughout the Sahel and the Cape region. These new risk maps provide a valuable starting point for understanding the zoonotic niche of CCHF, its extent and the risk it poses to humans. © The Author 2015. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene.
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Crimean-Congo Hemorrhagic Fever (CCHF) is a fatal infection, but no clinical case due to AP92 strain was reported. We described the first clinical case due to AP92 like CCHFV. A case infected by a AP92 like CCHFV was detected in Balkanian part of Turkey. Diagnosis was confirmed by RT-PCR and sequencing. A human serologic and tick survey studies were performed in the region, where the case detected. Thirty eight individuals out of 741 were found to be anti CCHFV IgM positive. The attack rate for overall CCHFV was calculated as 5.2%. In univariate analyses, CCHFV IgM positivity was found to be associated with the age (p < 0.001), male gender (p = 0.001), agricultural activity (p = 0.036), and history of tick bite (p = 0.014). In multivariate analysis, older age (OR: 1.03, CI:1.01-1.05, p < 0.001), male gender were found to be the risk factors (OR: 2.5, CI:1.15-5.63, p = 0.020) for CCHFV infection. This is the first human case with AP92 like CCHFV infection. Furthermore, this is the first report of AP92 like strain in Turkey. In the region, elderly males carry the highest risk for CCHFV infection.
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Crimean-Congo haemorrhagic fever (CCHF) is a viral zoonotic disease with a high mortality rate in humans. The CCHF virus (CCHFV) is transmitted to humans through the bite of Ixodid ticks or by contact with blood or tissues of infected livestock. In addition to zoonotic transmission, CCHFV can be spread from person to person and is one of the rare haemorrhagic fever viruses able to cause nosocomial outbreaks in hospitals. Crimean-Congo haemorrhagic fever is a public health problem in many regions of the world such as Eastern Europe, Asia, the Middle East and Africa. In addition to clinical symptoms, the diagnosis of CCHF is based on the use of serological tests for the detection of immunoglobulin M and immunoglobulin G antibodies and on the use of molecular tools such as RT-PCR. From 1970 to 1978, serological and epidemiological studies were performed in humans and in livestock of Iran. After two decades and observations of CCHF in some provinces of Iran, a CCHF surveillance and detection system was established in 1999, leading to a dramatically decreased mortality rate from 20% (year 2000) to 2% (year 2007).
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During the years 2000 to 2004, of 248 serologically confirmed cases of Crimean-Congo hemorrhagic fever (CCHF) that occurred in several parts of Iran, 169 were reported from Sistan-va-Baluchestan province. To assess the seroprevalence of CCHF virus infection within the Zahedan and Zabol districts of the Sistan-va-Baluchestan province in Iran, 300 subjects were sampled from the general population. In addition to blood sampling, a questionnaire was completed for every subject. All but just 3 of our 300 sampled subjects participated in blood sampling, and just 7 out of the 297 serum samples were found to be IgG ELISA positive. The point estimate of the seroprevalence was 0.024 (95% confidence interval: 0.003-0.044). A history of keeping livestock in houses (even for short periods) showed an association with seropositivity (P = 0.018). It seems that even occasional contact with livestock could be effective in transmission of the virus.
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Rhipicephalus sanguineus (the brown dog tick, kennel tick) has a world-wide geographical distribution. In Europe its original habitat is the Mediterranian basin, with sporadic introduction to northern countries. It is a three-host tick species, the dog being the primary host for all three developmental stages, but occasionally these can also attach to other mammals, even humans. This hard tick species is known for its capability to survive indoors, in houses. The authors review the geographical distribution, life-cycle, and significance of R. sanguineus as a vector that can transmit numerous pathogens. In August 2005, in North Hungary (Nógrád county, Zsunypuszta) on a beef cattle farm five engorged hard ticks were removed from the eyelids of a 2 year old, short-haired mixed breed male dog. Upon morphological examination all turned out to be nymphs of R. sanguineus. Sixteen days later a further engorged nymph was found on the same animal. To examine the presence of some important pathogens transmitted by this tick species, blood smears and serum samples of the dog were analysed, but they did not contain babesia developmental stages, or specific antibodies to Borrelia burgdorferi and Coxiella burnetii, respectively. Five further dogs were examined in the neighbourhood and were found tick-free. Extensive tick collection (by dragging/flagging) in four nearby forests revealed only 3 nymphs of Ixodes ricinus. However, 6 days later another dog became infested with R. sanguineus on the same farm. Both infested dogs were herding local cattle throughout their lives and neither the owners nor the dogs ever left the area (especially the country). The most likely introduction of these ticks in a younger stage (e.g. eggs in a fertilized female) was by a truck coming from Croatia to transport calves 40 days before the infestation was first detected.
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Larval Hyalomma truncatum ticks were infected with Crimean-Congo hemorrhagic fever (CCHF) virus by allowing them to engorge on viremic newborn mice. The overall tick infection rate was 4.4% (24/542). Virus was detected in specimens for greater than or equal to 160 days postinfection. Transstadial transmission to the adult tick stage was observed and horizontal transmission to a mammalian host was demonstrated. Horizontal transmission of CCHF virus to uninfected adult ticks occurred while feeding with transstadially infected ticks on the same host. No evidence of transovarial virus transmission from infected female ticks to their 1st generation progeny was observed.
Centers for Disease Control and Prevention
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