It was a little late in arriving, but West Nile Virus is making its presence known in the Central Valley.

Specifically, there have been a number of ground and a few aerial spraying operations in and around the Escalon area over the past few weeks.

“Overall in San Joaquin County, the last two weeks, we have seen a significant rise in West Nile Virus activity,” San Joaquin County Mosquito and Vector Control District Public Information Officer Aaron Devencenzi explained.

Around the county, last week, there were 36 positive samples of mosquitoes, collected in traps and six of those positive samples were collected in Escalon.

“There were 63 positive samples the week prior, 14 of those were in Escalon,” Devencenzi added.

A test sample is 50 or less mosquitoes collected in a trap.

The relatively high number of positive samples hasn’t translated to a huge number of human cases of the virus, with just two confirmed WNV cases so far in the county, according to Public Health officials. There are others that are possible WNV and are currently under investigation to determine if there are more human cases around the county.

Warmer weather over the past couple of weeks has seen the mosquito population show up, said Devencenzi, and they seem to be bringing the virus with them.

He added that the District is continuing its spraying for ‘nuisance mosquitoes’ by the rivers but also is targeting the WNV-carrying mosquitoes throughout the county with the ground and aerial spray operations.

He said there are five basic factors that are in play right now that mean people should be taking extra precautions against the mosquito bites.

“The number of positive mosquito samples, the infection rate in those mosquitoes and the weather, warmer temperatures.” Devencenzi said. “Also, the presence of dead birds (with the disease) and the presence of human cases.”

The spraying operations will continue until the WNV threat has subsided.

“It started out pretty mild this year but now we’re seeing the increased risk,” Devencenzi added.

Residents can also still get mosquitofish to use on their property to help reduce the presence of mosquitoes.

Contact the District at 209-982-4675 or visit www.sjmosquito.org to request them.

“We will deliver them out to you anywhere in San Joaquin County,” Devencenzi said.