The US state of Texas is battling an outbreak of the West Nile virus, the mosquito-borne disease that killed at least 16 people and continues to sicken hundreds, authorities said.
Throughout the state, 381 people have been sickened since the start of the year, according to the Texas Department of State Health Services.
"Texas is on track to have the most cases of West Nile illness since the disease first emerged in the state in 2002," it said in a statement.
"The City of Dallas is experiencing a widespread outbreak of mosquito-borne West Nile virus and has caused and appears likely to continue to cause widespread and severe illness and loss of life," Mayor Michael Rawlings said in the proclamation that takes effect Wednesday.
First discovered in Uganda in 1937, the virus is carried by birds and spread to humans by mosquitoes.
Severe symptoms can include high fever, vision loss and paralysis, while milder manifestations of the virus can range from headaches to skin rashes.
According to the Centers for Disease Control and Prevention, as of Tuesday 693 cases of the virus have been reported country-wide so far this year, including 26 deaths. Texas tops the list of both cases and fatalities.
In 2011, Texas saw a total of 27 cases and two deaths, the CDC said. Country-wide, 712 cases and 43 fatalities were reported over that 12-month period.
In an effort to stem the number of new infections, Texas authorities have urged residents to use insect repellent before heading outdoors, remain inside at dusk and at dawn, dress in protective clothing and drain standing water that could become a breeding ground for mosquitoes.
Last month, officials in New York City said the West Nile virus had been detected on Staten Island, one of the city's five boroughs.