MENLO PARK — The mosquitoes that can carry yellow fever have been found again in Menlo Park, San Mateo County health officials have announced.
Larvae for the mosquitoes, Aedes aegypti, was found in the city on Thursday, according to the San Mateo County Mosquito and Vector Control District. The mosquitoes’ presence has been recorded 13 times this year in the area of Holy Cross Cemetery in Menlo Park, including the first larvae found on Jan. 22.
Aedes aegypti mosquitoes can carry several viruses including yellow fever, dengue and chikungunya, a viral disease that causes fever and severe joint pain. They are not native to California but are common in urban areas of the southeastern portion of the country. The yellow fever mosquitoes are black and white and about a quarter-of-an-inch in size.
“The Yellow Fever mosquito — not the disease — has been identified,” said Robyn Thaw of the San Mateo County Department of Public Health.
“To date, no illnesses associated with this mosquito have been reported in California, and the risk of transmission remains low,” she said.
“However, it’s important to ensure this species does not become established in any community and that every effort is taken to eradicate this mosquito population.”
The Aedes aegypti mosquitoes were detected in San Mateo County on Jan. 22 and again on April 10. The mosquito species also was found in the same area last summer.
The mosquito must be infected with the virus to transmit disease to humans.
Of the nine cases of yellow fever found in the United States over the past 30 years, all involved travelers returning from Africa or Latin America and were not acquired in the United States, according to the Centers for Disease Control and Prevention.
Yellow fever appeared in the United States in the early 20th century but went away as a result of public health campaigns and improved sanitation and living standards.
The mosquito-borne disease, for which there is no cure, strikes about 200,000 people worldwide each year and kills about 30,000 of them. One yellow fever vaccine shot confers lifetime protection.
San Mateo County sees the mosquitoes as a threat. “Our goal is to eradicate this mosquito population,” Robert Gay, a mosquito and vector control district manager, said in a news release.
The district has expanded its surveillance area for yellow fever mosquito. The district is deploying traps for mosquitoes and mosquito eggs in the areas where the Aedes aegypti have been found, district officials said.
District employees also conduct door-to-door inspections and look for standing containers of water at homes.
Residents are advised to dump any standing water outside of their homes where mosquitoes tend to lay their eggs.
In 1979, the district eradicated yellow fever mosquitoes found near the San Francisco International Airport.
Last year, 14 larvae and three adult yellow fever mosquitoes were found around Holy Cross Cemetery between August and October, according to district officials.
Bay City News and staff writer Lisa Krieger contributed to this story.
