Yellow fever, dengue fever, Zika, those are serious diseases usually found in remote tropical environments, but Contra Costa County officials sounded the alarm because the mosquitoes that transmit those viruses have been found in the area.
Now they are preparing a major offensive to kill them before they go into hibernation.
“We found invasive mosquitoes in Antioch, and it is the species aedes aegypti, the yellow fever mosquito,” said Paula Macedo, GM of the Contra Costa Vector Control District. “This isn’t a mosquito we’ve had here before.”
The Aedes aegypti, with their black and white stripes, are known as “ankle biters” because they usually attack the lower part of a person’s leg. And they are quite small, about the size of a grain of rice. But their biology means they can carry a number of serious diseases, including yellow fever and dengue.
The province normally only sees a few cases a year, in people who have traveled to other countries.
“If we have people carrying Dengue, and this mosquito bites the right person, they can transmit it to someone else,” Macedo said. “So when that happens, we call it a ‘locally acquired case’. And we don’t want that because it could cause an epidemic in the area.”
On Saturday, Vector Control District officials held an information meeting at a park in the contaminated area. The boundaries extend from Highway 4 in the north to Blue Rock Drive in the south to Lone Tree Way in the west and Deer Valley Road in the east. Crew members covered the area and searched the front and back yards for breeding sources, such as old tires.
“They do collect rainwater and these invasive species will lay their eggs there,” said an inspector who examined the backyard of a house in the area.
But an unmaintained swimming pool in the same backyard was a more serious breeding ground. It only took one scoop in the dirty water to detect the mosquito larvae.
The county can treat such sources to kill the developing larvae, and starting Tuesday, weather permitting, they will begin spraying neighborhoods with trucks to spray mosquito-killing bacteria over homes and in backyards.
Back at the park, Kimberly Born arrived with some concerns about that.
“I have two koi ponds in my backyard and my concern was the spray, whether or not I should cover my ponds,” she said, before getting the answer she was hoping for. “And whatever they sterilize won’t harm the animals or aquatic life. So I’m a happy camper.”
As she stared at a beaker full of swimming larvae, 8-year-old Brooke Mann explained why many people breed mosquitoes without realizing what they are.
“They’re tortuous. They look like tadpoles, but smaller,” she said.
It’s a serious threat and the county says it will spray neighborhoods because there is only a short window to kill the mosquitoes before cooler weather sends them into hibernation.
“Just like the Medfly was many decades ago, I’m sure people will be freaking out about it,” said resident Ken De Silva. “But you know, the alternative is we have yellow fever or Zika or something.”
And the province won’t take ‘no’ for an answer.
“Ultimately, for the house that wouldn’t let us in, we’re going to get a code enforcement warrant to get in,” Macedo said. “We’ll come in no matter what. So if you let us in now or in two weeks while enforcing the code, it’s your choice. But as a public health agency we have the right to do this, to protect public health.”
Aedes aegypti are well adapted for survival. Their eggs can survive for six months after the water source dries up. Southern California has been battling the mosquito for a few years now, and so far this year they have had six locally acquired cases of Dengue in Los Angeles and one in San Diego.
In the Bay Area, they emerged two years ago in Martinez, but the eradication was successful.
“Here (in Antioch) the area is much more widespread and I am very concerned,” Macedo said.
So officials are now trying to kill as many people as possible before the weather starts to warm in April and the population has a chance to really take off.
