West Nile Fever and West Nile Encephalitis are caused by the Flavivirus West Nile Virus (WNV). West Nile Virus is now a dangerous threat for horses, birds and humans.

Japanese encephalitis virus (JEV) is a significant vector-borne zoonotic pathogen, causing devastating encephalitis in humans. Its geographical range includes a majority of Asian countries and has also been recognized in some western Pacific areas. The main vectors of JEV are mosquitoes belonging to the genus Culex. Birds and pigs function as hosts and virus amplifiers, whereas humans are accidental hosts. Japanese encephalitis is commonly regarded as a rural disease.

Japanese encephalitis virus (JEV) is one of the leading causes of acute encephalitis in humans. The virus is spread by mosquitoes, mainly belonging to the Culex species. The main reservoirs are considered to be birds and pigs, with pigs constituting the most important reservoir in regard to human infection. During the last few decades the production of pork has increased significantly in Vietnam. With 90% of pigs being kept in households owning 10 pigs or less, pigs are widely spread across most parts of the country.