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Jamestown Canyon Virus and Powassan Virus

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Jamestown Canyon Virus and Powassan Virus Jamestown Canyon and Powassan: Arboviruses of Epidemiological Concern in the Northeastern and Midwestern United States Erica Vecchio, Microbiologist, Virology and Serology Dr. Nicolas Epie, Division Director, Virology and Serology Arboviruses • Arboviruses = “Arthropod-borne” viruses - Approximately 80-85% of all known species on Earth - Include insects, arachnids, crustaceans and other animals - May serve as vectors of disease Insects Arachnids Classification of Arboviruses • Arboviruses of concern in the United States are classified into the following families: - Flaviviridae - Yellow Fever - Bunyaviridae - La Crosse - Togaviridae - (Alphaviruses) - EEE - Reoviridae - Colorado Tick Fever Transmission of Arboviruses •Primary transmission •Secondary transmission in rarer cases Primary Transmission Cycle Background of Arboviruses • The geographical endemic area of arboviruses continues to expand. • In 2017, 2,291 (70% neuroinvasive) domestically acquired cases were reported in the United States: - 92% - West Nile virus cases - Two lesser-known arboviruses also noted: • Jamestown Canyon virus (genus Orthobunyavirus) - Mosquito-borne • Powassan virus (genus Flavivirus) - Tick-borne Mosquito-Borne Diseases • The most recognized vectors of human diseases • Found in virtually every region of the world • Transmitted diseases: -Chikungunya -St Louis Encephalitis -Dengue -West Nile -EEE -WEE -La Crosse -Yellow Fever -Malaria -Zika, etc. The yellow fever mosquito (Aedes aegypti) transmits yellow fever, dengue, Zika, and other viruses. Mosquito-Borne Diseases • Most mosquito-borne diseases are endemic to tropical and subtropical parts of the world. • The United States experienced sporadic outbreaks of dengue, malaria, and yellow fever in the past, but all are now rare in the U.S. • Eastern equine encephalitis (EEE), La Crosse, St. Louis encephalitis (SLE), West Nile, and Western equine encephalitis (WEE) continue to thrive. • Aedes and Culex mosquitoes are found throughout the country. Jamestown Canyon Virus (JCV) • The genus Orthobunyavirus includes the California group of seroviruses, the only members of this genus found in North America: - La Crosse (LACV) - California encephalitis (CE) - Keystone - Snowshoe hare (SSHV) - Jamestown Canyon virus (JCV) • The structure of JCV is a helical enveloped virus. • The genome is a three-segment negative sense RNA virus. By Nossedotti (Anderson Brito) - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=149 62209 History of JCV in North America • First isolated in 1961 from a Culiseta inornata mosquito. • Recognized in 1980 and became reportable to the CDC in 2004. • Testing began in 2013. • Increase possibly due to: - Intensified surveillance in the Midwest - Rising awareness of the disease among health officials and medical personnel, leading to improved testing procedures - Historical underreporting of cases Case Numbers • JCV and LACV cases in the U.S. in 2017: 75 for JCV versus 63 for LACV. • Additionally, the number of JCV infections reported to the CDC appears to be increasing over recent years: Reported Years Number of JCV Disease Cases 2000-2013 31 2014-2016 37 2017-2018 116 *2019 statistics are not yet available JCV Disease Cases Reported by Patient State of Residence States of Residence: • Connecticut • Louisiana • Maine • Massachusetts • Michigan • Minnesota • Mississippi • Montana • New Hampshire • New Jersey • New York • North Carolina • Ohio • Oregon • Rhode Island • Tennessee • Wisconsin Jamestown Canyon virus neuroinvasive disease cases reported to CDC by state of residence, 2009–2018 JCV Disease Cases Annual Incidence Reported by Patient County of Residence Serological testing of mosquitoes and wildlife reveal that JCV is geographically widespread within the United States, but human disease incidence is concentrated primarily in New England (New Hampshire, Massachusetts, New York, etc.) and the Upper Midwest (Minnesota and Wisconsin). Average annual incidence (per 100,000 population) of Jamestown Canyon virus neuroinvasive disease cases reported to CDC by county of residence, 2009–2018 JCV Vectors and Reservoirs • JCV is transmitted to humans primarily by mosquitoes, but 3 species of horseflies have also been found to carry the virus. • Insects obtain the virus by feeding on infected white-tailed deer and other mammals. Eastern tree-hole mosquito (Ochlerotatus triseriatus), a mosquito vector of the virus. JCV circulates in populations of white-tailed deer. JCV Vectors and Transmission • More than 26 species of mosquitoes are carriers of JCV • Aedes and Ochlerotatus – 2 recognized mosquito transmitters • Variety of mosquitoes carry JCV – cyclical transmission • Transovarian transmission—transmission to mosquito eggs: - This strategy helps perpetuate the virus through overwintering in eggs. JCV and Transmission •Primary mammalian reservoir is white-tailed deer •Other wild mammalian hosts including bison, elk, etc. •Humans and animals classified as dead-end hosts •JCV not spread by coughing, sneezing, or skin contact JCV Disease — Symptoms • Many people infected with Jamestown Canyon Virus Disease are asymptomatic. • Symptoms appear in others between 2 and 14 days, resulting in mild to moderate illness: - Fever - Headache - Fatigue - Photophobia - Upper respiratory signs – runny nose, cough, sore throat - Muscle and joint aches JCV Disease — Symptoms • Disease progression: - Roughly half of symptomatic JCV cases require hospitalization. - More severe conditions may develop due to meningitis or, more rarely, encephalitis: • Severe headaches • Neck rigidity • Gait/balance issues • Dizziness • Confusion • Tremors and/or seizures • Mortality from JCV is rare but possible; at least three deaths have been reported. JCV - Clinical Presentation • The transmission period of the virus is reported from spring into early fall (April to September). - Snowmelt Aedes species emerge in early spring. - Several other mosquito species are capable of transmitting the virus in the summer and early fall. • All ages and both genders have been infected, but victims appear to be predominately adult males with a median age of 58 to 63 years. - Greater outdoor exposure? - Decreased use of mosquito repellent? JCV Disease — Diagnostic Testing • Important for diagnosis with acute fever, meningitis, or encephalitis when exposed to mosquitoes. • Serum or CSF may be tested for IgM antibodies by MAC. • ELISA results are confirmed by plaque reduction neutralization (PRNT) tests or RT-PCR on serum or CSF. Treatment • Supportive care is available as no effective treatment is currently in place. This includes managing symptoms. • More critical cases - cerebral edema and intracranial pressure may need reduction. • No vaccine exists for JCV disease. • Prevention is the most important method to combat the disease. Prevention • Limit outdoor activities in mosquito areas. • Wear protective clothing. • Use mosquito repellants. • Pre-treat clothing with permethrin-based sprays. • Keep screens on open doors and windows. • Inspect yards for items with water pooling (i.e., tires, wheelbarrows, ditches, puddles). Prevention • Frequently empty/replace standing water. • Clean gutters so water does not collect and stagnate. • Fill tree holes that hold water with dirt or sand. • Cover or drill holes in trash and recycling containers that are kept in open areas outside. • Keep pools maintained, chemically treated, and/or covered when not in use. • Stock ornamental ponds with predatory fish such as goldfish, koi, and mosquito fish. Governmental Measures • Vector control measures (including inspection and spraying) should be practiced by municipalities. • Screening of blood donations for Jamestown Canyon virus is advisable. As of 2018, no cases of disease acquired from blood transfusions had been reported. Powassan Virus By Nossedotti (Anderson Brito) - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=14962176 Tick-Borne Diseases • Less focus on tick-borne diseases • Bacteria, protozoans, and/or viruses transferred to human populations: - Babesiosis (protozoal) - Lyme (bacterial) - Rocky Mountain spotted fever (bacterial) - Tick-borne encephalitis (viral) Tick vector for Rocky Mountain spotted fever Tick-Borne Diseases • Global distribution of ticks • Northern temperate regions are the particular locales of tick- borne encephalitis viruses • In the United States: - Tick-borne arboviruses and tick-borne diseases in general are a considerable public health concern. - The greatest number of vector-borne infections are tick-borne. - Additionally, disease rates have been steadily increasing in recent decades. Powassan Virus • In the past 20 years, Powassan virus (POWV) disease has received attention as an emerging arbovirus. • POWV is a member of the family Flaviviridae. • Of the tick-borne encephalitis flaviviruses, POWV is the only species found in North America. • The structure is an icosahedral enveloped virus. • The POWV genome consists of single-stranded, positive-sense RNA virus. History of POWV in North America • POWV was isolated from Dermacentor andersoni ticks in Colorado in 1952. • In 1958, identified from CNS autopsy specimen of a 5-year- old who died from encephalitis. • The first case of POWV disease in a U.S. citizen was diagnosed in New Jersey in 1970. • In 1996, a subtype of POWV, the deer tick virus (DTV), was discovered in Ixodes ticks. • POWV neuroinvasive disease became reportable to the CDC in 2001, and POWV non-neuroinvasive disease in 2004. Case Numbers • Reported
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