By Stan Deresinski, MD, FACP, FIDSA
Clinical Professor of Medicine, Stanford University
Dr. Deresinski reports no financial relationships relevant to this field of study.
SYNOPSIS: Ross River virus, Sindbis virus, Kyasanur Forest disease, Lassa fever, avian influenza, MERS-CoV, and Seoul virus are among the viruses currently causing outbreaks.
The Americas are on the alert for a variety of introduced viral infections, including Zika, West Nile, yellow fever, and chikungunya, to name some. But there are many other fascinating viral infections currently actively causing disease throughout the world.
Ross River Virus1
Australia has had its most intense season of Ross River virus infection in many years, with a greater than five-fold increase over the same period. A total of 430 cases were reported in the first six weeks of 2017. Ross River virus is an alphavirus transmitted by a variety of mosquitoes, including Aedes and Culex species, with wallabies and kangaroos serving as the reservoir. Like other alphaviruses, severe arthralgias are often a prominent complaint of those infected.
Sindbis Virus2
About 45 patients in South Africa, most of whom were residents of Johannesburg, developed fever and rash, and some developed severe arthralgias. Among those for whom laboratory investigation was available, one was infected with West Nile virus, but the remainder had Sindbis virus infection. In addition to South Africa, Europe, Eurasia, Oceania, and Australia are areas where Sindbis virus infections are known to occur. As an alphavirus, Sindbis infection may be associated with severe, sometimes persisting, arthralgias.
Kyasanur Forest Disease3
Multiple Indian villages have been affected with Kyasanur Forest disease, and emergency vaccination programs are being implemented. Kyasanur Forest disease is a tick-borne flaviviral infection that primarily affects monkeys (it is commonly called “monkey fever”), and die-offs of these primates often herald impending human cases.
Lassa Fever4
As of March 1, 2017, more than 150 people have died due to Lassa fever in West Africa, with most occurring in Nigeria. The infection is believed to be acquired through contact with food or household objects that have been contaminated with rat feces or urine. As many as 20% of those infected develop hemorrhagic fever.
Avian Influenza A(H7N9)
Yearly epidemics of human infections due to avian influenza A(H7N9) have occurred in China since 2013, and the current one, the fifth, is the most extensive, with 460 cases reported as of March 10, 2017.5 The virus contains a 4-amino acid insertion in a host protease cleavage site in hemagglutinin that has been associated with increased pathogenicity — and most have caused severe respiratory illness with high mortality.
MERS CoV
A total of 1,917 laboratory-confirmed cases of MERS-CoV infection have been reported to the WHO; at least 684 of these resulted in death.6 Cases continue to occur, and there is no end in sight.Twelve new cases with three deaths were reported from Feb. 6-21, 2017. While human-to-human transmission occurs, most cases are the result of exposure to dromedary camels or ingestion of their raw milk. There remains concern about introduction to countries outside the Middle East as the result of human travel, as previously occurred with its introduction into South Korea, which resulted in an epidemic affecting 186 individuals, 36 of whom died.
Seoul Virus
Eight individuals who worked at rat breeding facilities in Illinois and Wisconsin developed infection due to the Seoul virus.7 Five of the six infections in Illinois were asymptomatic, and all eight patients recovered. As of March 9, 2017, 17 people in seven states have been infected. The Seoul virus is a hantavirus that has worldwide distribution and is reported to cause less severe disease than other hantaviruses, but it may cause hemorrhagic fever with renal syndrome in some patients, and an estimated 1-2% die.
REFERENCES
- Ross River virus — Australia (05): (New South Wales). Archive Number: 20170307.4885428. Available at: http://www.promedmail.org. Accessed March 11, 2017.
- Arbovirus clusters — South Africa: West Nile, Sindbis, alert. Archive Number: 20170224.4861086. Available at: http://www.promedmail.org. Accessed March 11, 2017.
- Kyasanur Forest disease — India (03): (MH,KA) Archive Number: 20170223.4852280. Available at: http://www.promedmail.org. Accessed March 11, 2017.
- Lassa fever - West Africa (09): Nigeria (BO) Archive Number: 20170302.4875164. Available at: http://www.promedmail.org. Accessed March 11, 2017.
- Iuliano AD, Jang Y, Jones J, et al. Increase in human infections with avian influenza A(H7N9) virus during the fifth epidemic — China, October 2016–February 2017. MMWR Morb Mortal Wkly Rep 2017;66:254–255.
- WHO. Middle East Respiratory Syndrome coronavirus (MERS-CoV) — Saudi Arabia. Available at: www.who.int/csr/don/10-march-2017-mers-saudi-arabia/en/. Accessed March 10, 2017.
- Hantavirus update — Americas (05): USA (Illinois, Wisconsin) Seoul virus. Archive Number: 20170122.4782661. Available at: http://www.promedmail.org. Accessed March 11, 2017.
Ross River virus, Sindbis virus, Kyasanur Forest disease, Lassa fever, avian influenza, MERS-CoV, and Seoul virus are among the viruses currently causing outbreaks.
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