In what is being called a slow start to the annual West Nile Virus season, officials said 27 birds have tested positive for the sometimes deadly virus in California so far this year, eight of them in Sacramento County.
"There have been other years, like 2014 or 2016, where we've seen a lot more activity," said Luz Robles, the public information officer for the Sacramento-Yolo Mosquito and Vector Control District.
No human cases of the sometimes deadly virus been reported in the region this year. Just four cases have been confirmed elsewhere - in Los Angeles, Kern and Riverside counties - by the California Department of Public Health.
But officials are still urging people to be proactive in eliminating mosquito breeding grounds and protecting themselves.
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"It's time for people to be aware that mosquito season is in full swing," said Carla Hass, the director of communications for El Dorado County.
The season starts as early as April but usually doesn't kick in until May or June when steady warm temperatures arrive.
In most cases, the virus is spread through the bite of an infected mosquito, according to the California West Nile Virus website. Birds such as crows, ravens, finches and magpies act as hosts for the disease. Mosquitoes become carriers of the disease after they feed on an infected bird.
“Essentially, it’s a virus that presents itself with flu-like symptoms," Hass said. "Symptoms can range from just not feeling right to fever and fatigue.”
The vast majority of people who have contracted the disease don't have any symptoms, but 20 percent of cases will develop into what is referred to as West Nile Virus fever, Robles said. Symptoms of the fever include headache, fatigue, swollen lymph nodes and joint pains — unusual symptoms in the summer months.
The most serious cases can lead to life-threatening conditions such as meningitis and encephalitis, according to the Johns Hopkins Medicine Health Library.
Last year, 253 human cases of West Nile Virus were confirmed in California and there were 44 fatalities, Robles said. Six human cases were reported in Sacramento County in 2017 and six in Yolo County with no fatalities in either county.
In the last five years, there have been two reported human cases of the virus in El Dorado County.
Although there is no vaccine to prevent the spread of West Nile Virus, people can take precautions to lower the chance of contracting the virus.
“Mosquitoes can go from eggs to adults in four to seven days," Robles said. “We want to make sure people are not breeding mosquitoes around their homes. Anything that can hold standing water for more than a few days can and will become breeding grounds.”
Standing water can take the form of neglected pools, but can also take less obvious forms, such as dog dishes placed outside and dishes underneath potted plants, she said.
A press release from El Dorado County recommends draining standing water around the property and keeping water in swimming pools, ponds and water troughs circulating. It also recommends using a biological larvicide called "Mosquito Dunks" or adding mosquito fish to backyard ponds.
The Mosquito and Vector Control District provides free home inspections and has mosquito fish available for pick-up and delivery. Mosquito fish can eat 200 to 300 mosquito larvae per day.