MICROBIOLOGY

• Japanese encephalitis virus (JEV) is a mosquito-borne flavivirus similar to the St. Louis encephalitis virus, Zika, Murray Valley encephalitis, yellow fever, Dengue, and West Nile virus.[9]
• JEV is a single-stranded, positive-sense, enveloped RNA virus transmitted by Culex mosquitoes in tropical and temperate areas.[8]
  • Wild birds are natural hosts, and domestic pigs, wading birds, and bats are amplifying hosts.
  • Blood transfusion and organ transplantation are potential modes of transmission.
• JEV is endemic in Asia, Southeast Asia, and the Pacific Islands, causing about 70,000 cases of infection and 14,000-20,000 deaths per year worldwide.[16]
  • CDC list of countries: https://www.cdc.gov/japaneseencephalitis/maps/index.html
• The recent detection of JEV in multiple commercial piggeries across four temperate southern Australian states led to a "Communicable Disease Incident of National Significance" declaration on March 4, 2022.
  • Australian public health authorities report a sentinel case of lethal viral panencephalitis in a 45-year-old, at least 40 cases of infection, and five deaths.[7][3][4]
  • https://wwwnc.cdc.gov/travel/images/japanese-encephalitis-australia-map.png
• The risk of infection is estimated at 1/5000 per month of travel to rural areas of Asia where transmission occurs.
  • In temperate Asia, the incidence of cases peaks in summer and fall.
  • In the tropics or subtropics, transmission occurs in wet seasons but may occur year-round.
• Emerging risk in southern Europe via C. pipiens with JEV sequences found in mosquitoes and birds in Italy.[10]