West Nile virus Social history of viruses

west nile virus, flavivirus, first identified in 1937 when found in blood of feverish woman. virus, carried mosquitoes , birds, caused outbreaks of infection in north africa , middle east in 1950s , 1960s horses in europe fell victim. largest outbreak in humans occurred in 1974 in cape province, south africa , 10,000 people became ill. increasing frequency of epidemics , epizootics (in horses) began in 1996, around mediterranean basin, , 1999 virus had reached new york city. since virus has spread throughout us. in us, mosquitoes carry highest amounts of virus in late summer, , number of cases of disease increases in mid july september. when weather becomes colder, mosquitoes die , risk of disease decreases. in europe, many outbreaks have occurred; in 2000 surveillance programme began in uk monitor incidence of virus in humans, dead birds, mosquitoes , horses. mosquito (culex modestus) can carry virus breeds on marshes of north kent. mosquito species not thought present in uk, widespread in southern europe carries west nile virus.