Batai virus (BATV) is a zoonotic orthobunyavirus transmitted by a wide range of mosquito vectors. The virus is distributed throughout Asia and parts of Africa and has been sporadically detected in several European countries. There is increasing evidence that BATV is emerging in Europe as a potential threat to both animal and human health, having been detected in mosquitoes, mammals, birds and humans. In recent years, serological surveillance in cattle, sheep and goats has suggested an antibody prevalence of up to 46% in European livestock, although human serological prevalence remains generally low. However, the recent and continued spread of invasive mosquito species into Europe may facilitate the establishment of competent populations of mosquitoes leading to increased BATV transmission. Migratory birds may also potentially facilitate the emergence of BATV in geographical locations where it was previously undetected. Although BATV has the potential to cause disease in humans and livestock, our understanding of the impact in wild animal populations is extremely limited. Therefore, there is a need for increased surveillance for BATV in mosquitoes, livestock, wild mammals and birds in Europe to understand the true impact of this virus.

Japanese encephalitis (JE) is an infection that occurs predominantly in Asia and the Pacific Islands. It is transmitted by mosquito bites, with the main vector being Culex tritaeniorhynchus, and is maintained in enzootic cycles involving pigs, wild birds and mosquitoes. JE is caused by infection with Japanese encephalitis virus (JEV), a zoonotic pathogen that also causes disease in mammals such as pigs and horses. In humans, most symptoms are mild or flu-like but can progress to encephalitis. Pigs are considered amplification hosts, and sows may have gestational complications. Horses may exhibit neurological signs. Detection of the virus can be confirmed by serological or molecular laboratory tests. Vaccination offers protection against JEV infection in humans, pigs and horses. Whilst there is no effective treatment of JE, human cases may require hospitalization for supportive therapy, which may include administration of fluids, oxygen and medication to treat symptoms.

Graphical West Nile virus (WNV) is transmitted by mosquitoes in a mosquito-bird-mosquito enzootic cycle, with spillover infections in humans and horses. Created with BioRender.com.

Ticks are of medical and veterinary concern due to their role as vectors of a wide range of pathogens, including viruses, protozoa, and bacteria. Accurate species identification is essential during tick surveillance and disease control programmes, as certain pathogens are associated with particular tick species. In this study, genetic variation of a partial sequence of the cytochrome c oxidase I ( COI ) gene was used for molecular identification of tick species to corroborate morphological identification. This also enabled investigation of cryptic diversity within tick species. Thirty species belonging to the genera Amblyomma, Argas, Carios, Dermacentor, Haemaphysalis, Hyalomma, Ixodes, Ornithodoros , and Rhipicephalu s were assessed. Tree-topology analysis confirmed discrete clustering of specimens according to species for the majority of taxa. Intraspecific genetic divergence ranged from 0 to 6.08%. In taxa where species complexes are known, separation of discrete groups were found. Several species yielded >2% intraspecific genetic divergence when compared to other taxa, suggesting potential cryptic diversity. DNA barcoding was an effective approach for the morphological identification of UK and non-native ticks, and for the detection of cryptic diversity within species.

Japanese encephalitis virus (JEV) is a mosquito-borne orthoflavivirus and a major cause of human encephalitis throughout Asia, although it is currently not reported in Europe. To assess the potential impact of climate change, such as increased temperatures, and the potential for native Cx. pipiens to transmit JEV genotype I in the United Kingdom (UK), we have investigated vector competence at two different temperatures. Culex pipiens f. pipiens were provided a bloodmeal containing JEV genotype I at 7.8 × 10⁸ PFU/mL. Mosquitoes were maintained for 14 days at 21 °C or 25 °C, and rates of infection, dissemination, and transmission potential were assessed. There was no evidence for virus infection, dissemination, or potential for transmission at 21 °C. However, at 25 °C, virus infection was detected in 5 of 36 mosquitoes (13.9%). Of these, JEV disseminated to legs and wings in three specimens (3/5) and viral RNA was detected in saliva from one specimen (1/3). These data indicate that at elevated temperatures of 25 °C, UK Cx. pipiens f. pipiens could transmit JEV genotype 1.