Yaohui Fang

Hainan Island, located in the South China Sea, is known as an area with diseases related to Rickettsia spp. or spirochete infection; however, the potential threat there from infection with tick-borne viruses (TBVs) remains obscure. In the present study, the dominant tick species, including Rhipicephalus sanguineus and Rhipicephalus microplus, were collected in Hainan Island, and tick viromes were investigated by metagenomic sequencing. In total, 27 viral species were identified belonging to the families Orthomyxoviridae, Flaviviridae, Nairoviridae, Phenuiviridae, Totiviridae, Chuviridae, Rhabdoviridae, and Parvoviridae, amongst which one novel virus and 13 new strains were discovered. Subsequently, individual ticks were screened for seven TBVs, Huanggang Rhabd tick virus 1 (HRTV1), Lihan tick virus (LHTV), Mivirus (MIV), Guangdong tick quaranjavirus (GTQV), Wenchang Ephemerovirus (WEPMV), Jingmen tick virus (JMTV), and brown dog tick phlebovirus (BDPTV), resulting in high prevalence rates of 16.97%, 9.59%, 10.33%, 7.38%, 7.01%, 6.27%, and 3.69%, respectively. While co-infection with multiple viruses was more frequent in R. sanguineus, R. microplus ticks generally had higher viral loads. Four febrile patients showed antibody responses to three TBVs, one each to LHTV and JMTV, and two to GTQV; the patient with antibodies to JMTV also showed neutralizing activity against this virus. This study promoted our understanding of the diversity and complexity of the TBV community in Hainan Island. The results provide serological evidence that human exposure to TBVs like JMTV may have occurred in Hainan, raising concern about potential risks from TBVs and the need to perform further surveys of TBVs among ticks, animals and humans.

Tick-borne viruses (TBVs) pose significant public health and economic threats. Pakistan has endemic Crimean-Congo hemorrhagic fever virus (CCHFV), but evidence suggests broader TBV circulation. This study assessed the seroprevalence of thirteen TBVs (seven are members of the genus Orthonairovirus and six are members of the genus Bandavirus) in humans, livestock, and rats in Punjab, Pakistan. Serum samples (n = 794: 321 livestock, 253 human, and 220 rat) were collected from the Narowal, Lahore, and Faisalabad districts. Antibodies to viral NPs were detected using the luciferase immunoprecipitation system (LIPS). The overall seroprevalence was 19.14% (152/794); it was highest in livestock (27.10%), then humans (20.55%), and then rats (5.91%). The highest seroprevalence rates were 3.12% for CCHFV in livestock, 3.56% for Yezo virus (YEZV) in humans, and 0.91% for Tamdy virus (TAMV) and Tacheng tick virus 1 (TcTV-1) in rats. Neutralizing antibodies were detected against CCHFV (1 cattle, 4 humans), Bhanja virus (BHAV) (3 livestock, 1 rat), TAMV (1 cattle), Guertu virus (GTV) (1 cattle), and Dabie bandavirus (2 cattle). Sixteen samples showed antibodies to both orthonairoviruses and bandaviruses, indicating co-exposure. Further analysis showed that seropositivity was not randomly distributed. Livestock kept in commercial farming systems and people working mainly outdoors had distinctly higher exposure to TBVs than subsistence livestock and indoor workers. The results supported the circulation of TBVs among hosts within the close socio-economic/ecological integration area of Pakistan. These findings confirm the circulation of CCHFV, SFTSV, GTV, and TAMV; provide the first serologic evidence of BHAV in Pakistan; and underscore the need for further investigation into the potential circulation of additional TBVs. All results demonstrated that multiple TBVs have been circulating among humans, livestock, and rodents in Pakistan.

Arboviruses pose significant public health challenges globally, particularly in Pakistan, where deforestation, climate change, urbanization, inadequate sanitation, and natural disasters have all contributed to the spread of mosquito-borne flavivirus diseases like dengue fever. The lack of a thorough national surveillance system has made it difficult to determine the extent and distribution of these diseases. Concern has been raised by recent outbreaks of West Nile virus (WNV) and chikungunya (CHIKV) epidemics, which may lead to Zika virus (ZIKV) outbreaks in the future. Additionally, hospital-based surveillance has detected the Japanese encephalitis virus (JEV) in the region. Evidence also points to the presence of additional arboviruses in healthy populations, such as the Karshi virus (KSV), Tamdy virus (TAMV), Crimean–Congo hemorrhagic fever virus (CCHFV), and severe fever with thrombocytopenia syndrome virus (SFTSV). This review aims to address the risk factors linked to these diseases, provide specific policy recommendations for efficient disease prevention and control, and describe the epidemiological trends of these diseases in Pakistan while emphasizing the critical need for improved surveillance and thorough epidemiological investigations.