Philadelphia reports first West Nile Virus cases this season

West Nile virus is spreading in the Philadelphia region, with the city reporting its first cases of the season last week, per state and local data.

Why it matters: Most human cases are asymptomatic, but some infections can cause serious illness, including debilitating, long-term complications or death.

State of play: West Nile virus has been detected in mosquitoes in the majority of Pennsylvania counties this year, with at least a dozen human infections statewide, per the state .

• Philadelphia reported on Aug. 15 that two people were infected with a severe form of the virus that can affect the nervous system.
• Several other cases were reported in the region in recent months.

Driving the news: Health officials across the region tell Axios they're trying to minimize the risk of infection to people and birds, including by deploying surveillance programs and spraying water-bound areas where mosquitoes lay eggs.

• Since May, Philadelphia has sprayed for larvae and mosquitos at nearly 100 locations across the city.

Zoom in: Montgomery County, which has reported a single case, has set up about 500 mosquito traps this year.

• This week, the Hatboro Little League halted games at its complex after mosquitoes from a nearby trap tested positive for the virus, Richard Lorraine, the county's medical director, told Axios.

Meanwhile, Bucks County has spent about $170,000 on mosquito mitigation efforts this year. They've had two human infections so far this year, up from one last year.

• Raymond Buckley, Bucks County's mosquito disease control coordinator, tells Axios the county has had more than 10% of their traps test positive for the virus this year.

Generally, officials say they're seeing more positive pools in areas where there's creeks and canals.

By the numbers: More than 40% of 677 mosquito traps tested in Philadelphia since May were positive for the virus.

• Positive mosquito pools are scattered across Philadelphia, including Fairmount and Pennypack parks.
• Philadelphia County (325) is No. 1 in the state with the most positive pools, Bucks County (126) is fifth and Montgomery County (72) is ninth, per state and local data.

What they're saying: Health officials say people can take steps, such as wearing long sleeve shirts and using repellant, to protect themselves from being bitten by mosquitoes carrying the virus.

• But there's still a risk of contracting the virus throughout mosquito season, which runs from April to October, around when the first frost hits.

Other recommendations:

• Keep weeds and tall grass trimmed short, and drain standing water from yards and other spots like old tires and plant container trays.
• Clear roof gutters.
• Keep garden ponds clean and stocked with mosquito-eating fish or mosquito "dunks" — chemical pellets that dissolve and kill larvae.
• Repair door and window screens to keep mosquitos out of your home.