DOWNLOAD ANIMATION WITH VOICE-OVER: htnewsdirect.nma.com.tw DOWNLOAD ANIMATION ONLY: newsdirect.nma.com.tw West Nile Virus, a mosquito-borne illness that survives in birds has arrived early this year in the US following heavy rain and widespread flooding. Symptoms appear between 5-15 days after being bitten and can include mild fever, headaches and occasionally swollen lymph glands. In rarer cases, the virus can lead to a stiff neck, muscle weakness and encephalitis and will require patients to be hospitalized.