The city of Conway hopes that a new ordinance will stop people from keeping tires that hold standing water. The rule is designed to prevent West Nile virus, which is carried by mosquitoes. The measure also prohibits "any receptacle or condition" that holds stagnant water that allows mosquitoes to breed. Mosquitos acquire the virus from infected birds and transfer it to humans and animals when they bite. There is no vaccine or treatment for the virus, which leads to flu-like symptoms in about a fifth of humans infected. In rare cases, the virus can cause fatal brain swelling. In 2003, Arkansas had 26 human cases of West Nile virus but no deaths. In 2002, the state reported 43 human cases and blamed the virus for five deaths. The state Health Department urges Arkansas residents to remove standing water to help control mosquito populations.