Two mosquito samples from La Cañada Flintridge were found positive for the West Nile Virus last month, according to Thomas Dang from the Greater Los Angeles County Vector Control District, who presented an update on the West Nile Virus to the City Council on Oct. 17.
“As you know, mosquitoes are the world’s most deadly animal, mostly in other parts of the world where countries are still developing,” said Dang. “They do cause over 700,000 human deaths every year, unfortunately, many of them are child deaths.”
Examples of mosquito borne diseases include West Nile Virus, Zika, Malaria and Dengue, to name a few.
The Vector Control District’s mission is to control vectors such as mosquitos, midges and black flies in the greater Los Angeles area and protect residents from mosquito-borne diseases. Vector Control staff monitor insect activity through the surveillance of gutters, river channels, pools and ponds, provide service via request to private residential homes, take care of underground storm drains and perform mosquito trapping and disease monitoring.
“[We work in] a lot of public right-away places where these nasty little insects can breed and transmit diseases to us,” said Dang, noting that in California there have been 124 people who tested positive and were symptomatic for West Nile Virus, and six virus-related deaths so far in 2023.
In Los Angeles County so far this year, there have been 12 people who tested positive and were symptomatic for West Nile Virus, and one reported death.
“For the city of La Cañada Flintridge, we did identify through our mosquito trappings two West Nile Virus positive samples this year, and first detected them in September,” said Dang.
Historically, said Dang, the city has been very successful with controlling disease transmission. The last time there was a West Nile Virus positive sample was in 2017.
The Vector Control District educates city management and residents throughout the county. Dang, who personalized the presentation to the city last Tuesday, said that in 2021, “We have identified and confirmed 501 residential and public breeding sources, 87 pond and pool sources, and 164 underground storm drain sources where we confirmed mosquitoes breeding.”
He showed the Council the Southern California native Culez mosquito, which is the primary mosquito that transmits the deadly West Nile Virus.
He also presented the invasive Aedes mosquito which he described as, “the real problem mosquito.”
“They are the ones that you have been bitten by, they’re the ones that chase you inside your car and house and [will bite] through your clothes,” said Dang. “They mostly will bite you through your ankles, which you may have heard the media refer to them as ‘ankle biters,’ and these are invasive.”
In the case of the West Nile Virus, a female mosquito will bite a person and use their blood to lay her eggs. A mosquito can carry the virus after biting a bird that is infected.
“The cycle needs to be from bird to mosquito to human,” to be harmful, Dang said, but only 20% of people will develop symptoms.
The greatest risk is for those who are over 50 years old and those with weakened immune systems. There is no vaccine or treatment for West Nile Virus.
The main takeaway from the presentation, said Dang, is to be educated and prevent the breeding of mosquitoes by draining any standing water and throwing away unneeded, open containers that might collect rainfall.
“They only need a teaspoon of water to breed,” said Dang. “They are really, really successful in finding anywhere to lay eggs and to multiply. It’s a real big problem.”
Mayor Rick Gunter asked Dang if there is a particular time of year that mosquitoes come around now, because he feels like the insects are always present.
“They are becoming more of a year-round problem, and it’s something that we’re really trying to control,” Dang replied, also listing incidents that contribute to the problem such as hurricane Hilary and the weather still being warm in October.
“Thank you for all the good work,” said Gunter. “The reason we asked you to come is because we had [no cases] in 2017 and now, we have two this year, so I want to make sure we are on top of it and reminding our residents to take a quick look around their yard for mosquito breeding [areas].”
Dang told Council that if a community member feels they have an abnormal number of mosquitos, they can call for an assessment service at (562) 944-9656.
“We are available at your service,” said Dang.
For more information, see the mosquito source checklist and resources at glamosquito.org/mosquitoes.
First published in the October 26 print issue of the Outlook Valley Sun.
