virus cases in the following year. As drought can decrease fish and other populations that eat mosquito eggs, higher numbers of mosquitoes can result. Higher temperatures are linked to decreased time for replication and increased viral load in birds and mosquitoes. Research A vaccine for horses (ATCvet code: ) based on killed viruses exists; some zoos have given this vaccine to their birds, although its effectiveness is unknown. Dogs and cats show few if any signs of infection. There have been no known cases of direct canine-human or feline-human transmission; although these pets can become infected, it is unlikely they are, in turn, capable of infecting native mosquitoes and thus continuing the disease cycle. AMD3100, which had been proposed as an antiretroviral drug for HIV, has shown promise against West Nile encephalitis. Morpholino antisense oligos conjugated to cell penetrating peptides have been shown to partially protect mice from WNV disease. There have also been attempts to treat infections using ribavirin, intravenous immunoglobulin, or alpha interferon. GenoMed, a U.S. biotech company, has found that blocking angiotensin II can treat the "cytokine storm" of West Nile virus encephalitis as well as other viruses. As of 2019, six vaccines had progressed to human trials but none had been licensed in the United States. Only the two live attenuated vaccines produced strong immunity after a single dose. References External links CDC—West Nile Virus—NIOSH Workplace Safety and Health Topic West Nile Virus Resource Guide—National Pesticide Information Center Virus Pathogen Database and Analysis Resource (ViPR): Flaviviridae Species Profile – West Nile Virus (Flavivirus), National Invasive Species Information Center, United States National Agricultural Library. Lists general information and resources for West Nile Virus. Horse diseases Bird diseases Flaviviruses Arthropod-borne viral fevers and viral haemorrhagic fevers Zoonoses Tropical diseases Insect-borne diseases Animal vaccines Encephalitis Animal viral diseases Wikipedia medicine articles ready to translate