Maricopa County. Officials are asking residents to turn off their water supply.

The county, which seats Phoenix, has recorded more than 200 human cases and 12 deaths as of September 30, according to statistics from Environmental Services. The county had only three deaths last year.

WNV is spread primarily through mosquito bites. 

The main vector of WNV transmission is through mosquito bites.
(iStock)

One of those who died this year in Maricopa County is Nathan Ryberg, a former Tempe police detective. Ryberg’s death was confirmed Thursday, Sept. 23, less than two weeks after he reportedly went into a coma while fighting the virus.

MULTIPLE STATES WARN ON WEST NILE VIRUS RISK AMID PEAK PERIOD

West Nile Virus is a disease caused by a virus that is primarily spread through mosquito bites. Maricopa County Environmental Services says that WNV can be spread from mother to baby in rare instances. According to health experts, only 1 out of 5 infected people will experience symptoms.

County officials are urging residents to take steps to deprive mosquitoes of water, which is needed for every stage of the mosquito breeding process. This can be done by emptying, draining, or covering all things that can hold water.

County officials spray pesticides, or “fogging”, in areas where there has been a high level of mosquito activity. A county website shows which areas have been fogged the most in recent weeks.

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Last year marked one of the driest monsoon seasons on record. This year, Phoenix saw nearly four inches of rainfall.

The Associated Press contributed to this report.