Pasadena’s Public Health Department Leads Fight Against Mosquitoes Capable of Spreading Zika

While Southern California, indeed the entire United States, braces for outbreaks of the Zika virus, the city of Pasadena has a distinct advantage over many communities in the control of mosquitoes and the prevention of the disease.

Not only does Pasadena have its own Health Department but Pasadena’s Environmental Health Division operates its own vector control program, which works closely with other vector control districts and the California Department of Public Health to monitor, reduce and prevent the spread of infectious disease-carrying mosquitoes into Pasadena.

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Editor’s Note: This is the second and final part of our series looking at the threat of the Zika virus to the Pasadena area. The Centers for Disease Control continues to cite the virus, which causes birth defects in infants born to infected mothers, as a major threat to the health of American communities.

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Though the Zika-carrying mosquito species (aedis albopictus aka Asian Tiger Mosquito and aedis aegypti) have been located in the San Gabriel Valley, and as close as Altadena, they have not as of yet been reported in Pasadena. In addition, the species that has been identified in Altadena is not currently infected by the Zika virus, according to Michael Johnson, Director of the Pasadena Health Department.

Johnson explained further, “We do have concerns about the type of mosquito that has been identified in the San Gabriel Valley. It is one of those aedis albopictus mosquitos that is a potential carrier of Zika as well as some other mosquito-borne diseases that are a concern.”

“But,” Johnson continued, “we don’t have any evidence that the disease vectors are actually in those mosquito populations. At this point, it’s just the presence of that mosquito that raises our antenna.”

And, according to Dr. Joseph Wakoli Wekesa, scientific program manager at the San Gabriel Valley Mosquito and Vector Control District, it’s not unusual for mosquito species to live in a certain area and not necessarily expand to other cities, especially when they are being tracked and monitored.

Explained Wekesa,“Here in San Gabriel for the past five years, we’ve been tracking aedis albopictus, and in these trackings we find that the mosquitoes that set it off were in El Monte. They’ve been there for five years, this is their sixth year so far and we’ve got them now in Monrovia, and Arcadia. They were in only those two cities in 2013, and in 2014 they were in San Gabriel, Monterey Park, La Puente, and the City of Industry.”

“In 2015 they got into Azusa, parts of Glendora, and parts of West Covina and Covina,” Wekesa continued, “They have not reached Walnut, they have not reached San Dimas or La Verne or Claremont, and they’re not in the city of Sierra Madre.”

Nor Pasadena, largely because the city’s own vector control district conducts routine visual surveillance of identified standing water, and will apply larvicides to prevent mosquito breeding throughout the spring-fall mosquito breeding season, according to Johnson.

The various vector control departments are also in constant communication with each other, according to Wekesa.

“The City of Pasadena, has a vector control and a public health department,” Wekesa explained, “and their colleagues will call and ask, ‘What did you find?,’ ‘This is what we’re doing,’ and if there’s anything, I’ll let you know’. ”

Wekesa said that San Gabriel Valley Vector Control officials communicate with Pasadena’s vector control officials on a regular basis.

In fact, Johnson said, all of the regional vector control programs and districts share information, through phone communications, and in regional meetings.

Vector Control Districts also conduct trapping and testing of mosquitoes to identify breeds of mosquitoes, Johnson added.

Mosquitoes can also do a good job of keeping themselves hidden, according to Jason Farned, public information officer with the San Gabriel Valley Mosquito and Vector Control District, who explained, “”The reason why these mosquitoes are becoming established in these areas is because they live very close to humans and they are extremely durable. They’re very hard to get rid of. So they lay their eggs on the inside of very small, usually man-made containers, and those eggs can lay viable for several months up to even a year or more, waiting for the right conditions to hatch. We’ve found them living comfortably in containers as small as a bottle cap.

“Just debris in the back yard that’s collected,” he continued, “even a chip bag or a plastic bag that’s blown into the corner of your yard could potentially collect sprinkler water and start growing these mosquitoes very easily.” According to the Center for Disease Control (CDC), the virus is transmitted from human to human by the bites of infected female mosquitoes. During the first week of infection, Zika virus can be found in the blood and passed from an infected person to another mosquito through mosquito bites.

According to Wekerka, the Tiger mosquitoes in California are particularly hardy and pernicious. “The mosquitoes first got here in a lucky bamboo plant from China in 2001, and just three years ago Aedes aegypti was first found in the Fresno area and it spread.” he said.

According to the CDC, there are a number of things residents can do to dramatically reduce the chances of mosquito infestation and a possible Zika outbreak.

Outside the home, residents should empty and scrub, turn over, cover, or throw out any items that hold water like tires, buckets, planters, toys, pools, birdbaths, flowerpot saucers, or trash containers, once a week. Mosquitoes lay eggs near water. Residents should also tightly cover water storage containers so that mosquitoes cannot get inside to lay eggs.

More information on local mosquitoes and diseases is available at this link: http://www.glacvcd.org/vector-information/mosquitoes/invasive-mosquitoes/