Detection of Crimean-Congo hemorrhagic fever virus in blood-fed Hyalomma ticks collected from Mauritanian livestock.

BACKGROUND: Crimean-Congo hemorrhagic fever virus (CCHFV) belongs to the genus Orthonairovirus (Nairovididae) and is a (re)emerging tick-borne pathogen. It is endemic in most parts of Africa, Asia and southern Europe, and can cause severe hemorrhagic symptoms in humans, with high fatality rates (5-30%). METHODS: Hyalomma ticks were collected from four different livestock herds (cattle and camels) in Mauritania in 2018. The tick species were determined morphologically and confirmed molecularly by using the cytochrome oxidase 1 gene marker. For the detection of CCHFV, ticks were tested individually by one-step multiplex real-time reverse-transcriptase quantitative polymerase chain reaction. The small segment of all positive samples was sequenced to determine the CCHFV genotype. RESULTS: In total, 39 of the 1523 ticks (2.56%) collected from 63 cattles and 28 camels tested positive for CCHFV. Three Hyalomma species were identified. Hyalomma rufipes had the largest proportion of positivity (5.67%; 16/282), followed by Hyalomma dromedarii (1.89%; 23/1214). No Hyalomma impeltatum tested positive (0%; 0/21). Positive ticks were found in only six out of 91 host animals. Viral sequence analysis revealed the presence of two different CCHFV lineages (Africa I and Africa III). CONCLUSIONS: In this study, 2.56% of Hyalomma ticks collected from camels and cattle in Mauritania tested positive for CCHFV. However, the true prevalence of CCHFV in unfed ticks may be lower, as a considerable number of ticks may have been passively infected during blood-feeding by co-feeding ticks or due to viremia of the host. The results indicate the need to track the actual area of circulation of this virus.

Comparison of whole genomes of tick-borne encephalitis virus from mountainous alpine regions and regions with a lower altitude.

Tick-borne encephalitis (TBE) has been a notifiable disease in Germany since 2001. Its causative agent, the TBE virus (TBEV), is the most important arbovirus in Europe and Northern Asia. The illness, caused by the European Subtype usually displays flu-like symptoms, but can result in sequelae and, in 2 % of all cases, in death. Over the last few decades, the virus has spread into new habitats, such as higher altitudes in the Alpine region. For this study, it was hypothesized that the environmental challenges that the virus might be exposed to at such altitudes could lead to the selection of viral strains with a higher resilience to such environmental factors. To determine whether strains identified at higher altitudes possessed different genetic traits compared to viruses from lower altitudes, an analysis of viral genomes from higher Alpine altitudes (> 500 m above sea level) (n = 5) and lower altitudes (< 500 m above sea level) (n = 4) was performed. No common phylogenetic ancestry or shared amino acid substitutions could be identified that differentiated the alpine from the lowland viral strains. These findings support the idea of many individual introductions of TBEV into the alpine region and the establishment of foci due to non-viral specific factors such as favorable conditions for vector species and host animals due to climate change.