Washington, Aug 4 (IANS) The US has been badly hit by mosquito-borne West Nile virus, with 241 cases of the disease, including four deaths, reported nationwide so far this year, CNN reported Saturday.
Of the 42 states that have reported infections in people, birds or mosquitoes, three -- Texas, Mississippi and Oklahoma -- had as much as 80 percent of cases, health officials said.
In the US, most infections occur between June and September, and peak in August, officials said.
Symptoms include fever, headache, body aches, joint pains, vomiting, diarrhoea, or rashes.
Less than one percent develop a serious neurologic illness such as encephalitis or meningitis -- inflammation of the brain or surrounding tissues.
People over the age of 50 and those with cancer, diabetes and kidney disease or with organ transplants are at greater risk.
CNN said there are no medications to treat West Nile virus or vaccines to prevent infection. People with milder illness typically recover on their own but those more seriously affected may need hospital care.