Anlmal,Plant and Flsherles Quarantine and Inspection Agency

□ West Nile virus 1. Definition - Zoonotic mosquito-transmitted arbovirus 2. Aetiology - Family Flaviviridae, Genus Flavivirus, Japanese Encephalitis Antigenic Complex, West nile virus 3. Host range - Wild birds, human, horse etc. 4. Geographical distribution - Africa, Europe, the Middle East, west and central Asia, Oceania (subtype Kunjin), and most recently, North America. 5. Transmission - West Nile (WN) virus is amplified during periods of adult mosquito blood-feeding by continuous transmission between mosquito vectors and bird reservoir hosts - Infected Mosquitoes. Most often, WNV is spread by the bite of an infected mosquito. Mosquitoes become infected when they feed on infected birds. Infected mosquitoes can then spread WNV to humans and other animals when they bite. - Transfusions, Transplants, and Mother-to-Child. In a very small number of cases, WNV also has been spread through blood transfusions, organ transplants, breastfeeding and even during pregnancy from mother to baby. - Not through touching. WNV is not spread through casual contact such as touching or kissing a person with the virus. 6. Incubation period - Incubation period is 3 ~ 15 days 7. Diagnosis - Clinical Diagnosis In Wild birds may exhibit neurological signs prior to death In horse The majority of infected horses do not display clinical signs Fever is an inconsistently recognised feature. Mild to severe ataxia. Additionally, horses may exhibit weakness, muscle fasciculation and cranial nerve deficits In human Most persons who become infected with West Nile virus (WNV) develop no clinical illness or symptoms West Nile Fever : Fever, Headache, Fatigue, Skin rash on the trunk of the body (occasionally), Swollen lymph glands (occasionally), Eye pain (occasionally) Severe Disease: West Nile Meningitis, West Nile Encephalitis, and West Nile Poliomyelitis - Lab. Diagnosis Virus isolation using cell culture (Vero, RK-13 etc) Identification of virus : Immuno-histochemical (IHC) staining Reverse-transcription polymerase chain reaction Serological tests in equine : Equine IgM capture ELISA any species : Plaque reduction neutralisation Test 8. Control and eradication - In horse : WNV vaccination in U.S.A. - Vector control 9. Public health aspects - Zoontic disease 10. Further Information : http://www.oie.int/eng/normes/mmanual/A_00133.htm http://www.cdc.gov/ncidod/dvbid/westnile/index.htm