The Bunyavirales order is a large, diverse group of viruses encompassing over 400 recognized virus species. These viruses infect a variety of hosts, from plants to insects to rodents to humans. A common feature of human pathogenic Bunyaviruses is transmitted to humans via a vector such as mosquitoes, rodents, and ticks. Notable human pathogens within the order include rodent-borne Lassa fever virus and Hantaan virus, mosquito-borne Rift Valley Fever Virus, La Crosse encephalitis Virus (LACV), and the tick-borne Crimean-Congo hemorrhagic fever virus (CCHFV), Severe Fever with thrombocytopenia syndrome virus (SFTSV) and Heartland virus (HRTV). Clinical disease caused by these viruses varies from encephalitis to hemorrhagic fever, and case fatality rates for viruses such as Crimean-Congo hemorrhagic fever virus can be greater than 30%.
Tick-borne viruses are becoming an increasingly appreciated public health threat, and tick-borne bunyaviruses are no exception. CCHFV has a broad geographic distribution with reported cases, serological evidence, and presence in tick-vectors reported throughout Southern and Eastern Europe, Africa, the Middle East and Asia. Similar evidence of SFTSV is found in China, Korea and Japan. HRTV is a recently identified tick-borne bunyavirus in the United States. Importantly for public health, the geographic range of the tick vectors is expanding, placing new populations at risk. The principal vector of CCHFV, the Hyalomma tick has been found as far north as Sweden, and CCHFV-infected ticks have been found on long-ranging migratory birds threatening rapid introduction to new geographic regions. The vector for SFTSV, Haemaphysalis longicornis, was recently introduced to the United States, where it has rapidly become a widespread invasive species with little hope of eradication. Due to milder winters, tick populations are increasing, and increased human-tick contact will likely lead to increasing cases of HRTV. Thus, not only can tick-borne viruses rapidly move to new geographic regions, but their associated tick vectors can rapidly expand their geographic range, placing new populations at risk of infection.
Despite being a significant public health threat, key gaps exist in our understanding of tick-borne bunyaviruses. Beginning with virus-vector interactions and ecology, we have a limited understanding regarding the role of the tick in the viral life cycle, evolution and contribution to human disease. Even more, scarce information on vector distribution and spreading as well as host preferences, is available. The role of wildlife and livestock animals awaits being elucidated. Among humans infected with tick-borne bunyaviruses, the host responses that contribute to or protect from disease and how tick-borne bunyaviruses overcome these responses are largely unclear. Critically we lack available vaccines nor antivirals and further understand little about how candidate vaccines can confer protection.
This special issue is focused on highlighting these gaps in understanding of tick-borne bunyaviruses and seeks primary research and reviews focused on topics such as tick-borne bunyavirus discovery, model development, host and viral determinants of disease, tick-virus interactions, seasonal and spatial dynamics of ticks, the use of sentinel hosts animals, tick contributions to viral pathogenesis, and antiviral and vaccine development.
The Bunyavirales order is a large, diverse group of viruses encompassing over 400 recognized virus species. These viruses infect a variety of hosts, from plants to insects to rodents to humans. A common feature of human pathogenic Bunyaviruses is transmitted to humans via a vector such as mosquitoes, rodents, and ticks. Notable human pathogens within the order include rodent-borne Lassa fever virus and Hantaan virus, mosquito-borne Rift Valley Fever Virus, La Crosse encephalitis Virus (LACV), and the tick-borne Crimean-Congo hemorrhagic fever virus (CCHFV), Severe Fever with thrombocytopenia syndrome virus (SFTSV) and Heartland virus (HRTV). Clinical disease caused by these viruses varies from encephalitis to hemorrhagic fever, and case fatality rates for viruses such as Crimean-Congo hemorrhagic fever virus can be greater than 30%.
Tick-borne viruses are becoming an increasingly appreciated public health threat, and tick-borne bunyaviruses are no exception. CCHFV has a broad geographic distribution with reported cases, serological evidence, and presence in tick-vectors reported throughout Southern and Eastern Europe, Africa, the Middle East and Asia. Similar evidence of SFTSV is found in China, Korea and Japan. HRTV is a recently identified tick-borne bunyavirus in the United States. Importantly for public health, the geographic range of the tick vectors is expanding, placing new populations at risk. The principal vector of CCHFV, the Hyalomma tick has been found as far north as Sweden, and CCHFV-infected ticks have been found on long-ranging migratory birds threatening rapid introduction to new geographic regions. The vector for SFTSV, Haemaphysalis longicornis, was recently introduced to the United States, where it has rapidly become a widespread invasive species with little hope of eradication. Due to milder winters, tick populations are increasing, and increased human-tick contact will likely lead to increasing cases of HRTV. Thus, not only can tick-borne viruses rapidly move to new geographic regions, but their associated tick vectors can rapidly expand their geographic range, placing new populations at risk of infection.
Despite being a significant public health threat, key gaps exist in our understanding of tick-borne bunyaviruses. Beginning with virus-vector interactions and ecology, we have a limited understanding regarding the role of the tick in the viral life cycle, evolution and contribution to human disease. Even more, scarce information on vector distribution and spreading as well as host preferences, is available. The role of wildlife and livestock animals awaits being elucidated. Among humans infected with tick-borne bunyaviruses, the host responses that contribute to or protect from disease and how tick-borne bunyaviruses overcome these responses are largely unclear. Critically we lack available vaccines nor antivirals and further understand little about how candidate vaccines can confer protection.
This special issue is focused on highlighting these gaps in understanding of tick-borne bunyaviruses and seeks primary research and reviews focused on topics such as tick-borne bunyavirus discovery, model development, host and viral determinants of disease, tick-virus interactions, seasonal and spatial dynamics of ticks, the use of sentinel hosts animals, tick contributions to viral pathogenesis, and antiviral and vaccine development.