A fourth patient in Plano is fighting West Nile fever, the less severe form of West Nile virus.
Collin County Health Care Services confirms a person living in the 75025 zip code in the northern part of the city has contracted the illness.
Meanwhile the city is counting down the days until fall and continuing to test mosquitoes for West Nile virus.
"We set out the traps yesterday afternoon and pick them up in the morning," said Environmental Health Manager Geoff Heinicke.
The city started setting traps in early April, one month ahead of normal.
After a higher number of West Nile virus cases in 2012 and four human cases in Plano this year, the city decided to get a jump on the mosquito battle.
Plano has seen five infected mosquito pools and although the numbers are lower, they haven't slowed down.
"This year is turning out to be a more typical season," said Heinicke.
The city is also doing habitat monitoring in places that have thick brush, high grass, standing water and low flow creeks. On such area in East Plano has had positive mosquito tests.
Heinicke says they'll continue setting traps and testing mosquitoes through the first week in October, or until a major cold snap.