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Introduction We live in an age of constant change, due, to a large degree, to the continuing threat of infection by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causative agent of COVID-19. This recently emerged pandemic coronavirus has spread throughout the world. Countries or parts of countries have responded by locking down segments of their areas, in some cases, literally preventing the population from leaving their…

Introduction Omsk hemorrhagic fever is an acute disease caused by the Omsk hemorrhagic fever virus (OHFV) and is prevalent in some areas of western Siberia. OHFV is one of the tickborne flaviviruses that is known to cause hemorrhagic fever, in league with Kyasanur forest disease virus (KFDV) in southern India and the Alkhurma hemorrhagic fever virus (AHFV) variant subset of KFDV in Saudi Arabia, as well…

Introduction Alkhurma hemorrhagic fever virus (AHFV) is present in Saudi Arabia and surrounding regions. It has 89%–92% homology with Kyasanur Forest disease virus (KFDV), found primarily in India. Genome sequencing has revealed that AHFV and KFDV are very similar in polyprotein properties, C and E proteins, RNA–RNA interaction sequences, NS3 and NS5 polymerase, as well as 5′ untranslated region structures. AHFV is now classified as a…

Introduction The two lineages of Powassan virus (POWV) are the causative agents for Powassan neuroinvasive disease. A POWV Lineage 1 was initially isolated in 1958 in Powassan, Ontario, Canada, from the brain of a young boy who died of encephalitis. This virus bears some serological relationship to the Far Eastern tickborne encephalitis virus (TBEV-FE), formerly known as Russian spring–summer encephalitis (RSSE) virus. Both are members of…

Introduction and History The name of louping-ill virus (LIV) is derived from the old Scot word “to loup” (“leap”), in reference to an uncoordinated gait and tendency to jump seen in afflicted animals. Shepherds in the early 19th century knew that affected sheep came from certain upland heather pastures and that animals from disease-free pastures that were imported into the infected pastures were also at risk…

Introduction to Tickborne Encephalitis Virus and Its History Tickborne encephalitis virus (TBEV) is one of the most important tickborne arboviruses in Central and Eastern European countries, Russia, and parts of Asia, infecting at least 13,000 people annually despite the fact that it is not a reportable disease in China. There has been a 300% increase in human infections during the 10 years preceding 2018. At least…

Neglected Flaviviruses of Latin America Ilhéus and Bussuquara Viruses Ilhéus virus (ILHV) is found in humans and animals and is distributed over large areas of South and Central America, including Brazil, Peru, French Guyana, Columbia, Ecuador, Bolivia, Guatemala, Panama, and Trinidad. A large study of the seroprevalence of ILHV in Trinidad, however, failed to detect ILHV-specific antibodies in horses ( n = 506), cattle ( n = 163),…

Introduction Murray Valley encephalitis virus (MVEV) is one of several mosquito-borne flaviviruses of the Japanese encephalitis virus complex that causes severe disease in humans. It is restricted to a small region of Oceania and, with the exception of travel-related cases, has been exclusively reported in Australia and Papua New Guinea. It is endemic in tropical portions of the Northern Territory and Kimberley region of Western Australia,…

Introduction and History USUV was first identified in South Africa in Culex naevei mosquitoes in 1959 and subsequently spread to regions thousands of kilometers apart, such as Senegal, Central African Republic, Nigeria, Uganda, Burkina Faso, Cote d’Ivoire, and Morocco. At that time, it was not associated with clinical disease in birds or mammals. Recently, these and other flaviviruses have spread and are now found in Tunisian…

Introduction Australia hosts at least 75 species of arboviruses, several of which are associated with mild to life-threatening human disease. Among these are encephalitic flaviviruses, such as the Kunjin strain of WNV (KUNV), Japanese encephalitis virus (JEV), and Murray Valley encephalitis virus (MVEV). Australia is also home to Ross River and Barmah Forest alphaviruses, which cause severe, and sometimes chronic, polyarthritis. The numbers of locally acquired…

Introduction West Nile virus (WNV) was first isolated in 1937 in the West Nile district of Uganda and was subsequently reported in other areas of Africa, the Middle East, Europe, South Asia, and Australia. For decades, infections with WNV were generally mild and infrequent. This changed in the 1990s as severe disease became increasingly common and widespread, due at least in part, to commerce and the…

Introduction In 2014, a rare and mysterious disease began to be seen in newborns in Brazil. Babies afflicted with this disease had several distinctive features: severe microcephaly accompanied by neurological, developmental, and prominent skull abnormalities; decreased range of motion; and, in some cases, eye damage. The number of miscarriages and stillbirths also increased in the affected areas. The disorder spread rapidly throughout Latin America and to…

Introduction Dengue fever (DF) and the more serious forms of DENV infection, dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS), are currently found throughout much of the world. DF causes extreme bone pain. DHF and DSS are life-threatening, primarily in individuals who have been infected with one, and then another, of the four DENV serotypes. Dengue-related diseases are the most common vector-borne infections of humans,…