The Rise of the Mosquito

Close your eyes for a moment and imagine the deadliest animal on earth. Many of you may think of a menacing great white shark, raging rhinoceros, ferocious grizzly bear, ill-tempered hippo or a sneaky snake. Everyone hates snakes. But the biggest killer by far is the tiny mosquito. It takes 725,000 lives a year. One child every 30 seconds. It is also responsible for Up until now, mosquitoes have been considered only minor irritants here in the U.S. That's about to change. Thanks to rising temperatures, expect to see the rise of the mosquito. Pestilence, one of the four horsemen mentioned in Revelation, is on its way. But is there any cause for concern here in the Lehigh Valley. The answer seems to be Yes. 

Pennsylvania’s Department of Environmental Protection (DEP), has just released final counts for its surveys of West Nile Virus (WNV). With the wet weather, 2018 was one of the worst years to date for mosquitoes carrying the virus. A sampling of Northampton County mosquito pools turned up 83 positive results compared to only 17 reported in 2017. In Lehigh County, there were 151 positive results compared to just 74 last year.

“We take any threat to public health seriously,” said NorCo Executive Lamont McClure in a statement informing the public of these results. “Northampton County is committed to preventing the transmission of West Nile Virus to humans. In 2019 we will reopen our Vector Control Department. Since 2016, the County has contracted with the Penn State Extension services for West Nile and Zika Virus. As of December 31st, Penn State will no longer run those programs.”

Across Pennsylvania in 2018, there were 115 human cases of WNV recorded, with 8 deaths. The DEP reported a total of 107 avian cases and 108 veterinary cases of the virus. No human, avian or veterinary cases of WNV were reported in Northampton County. But in Lehigh County, four people were infected. 

WNV was first detected in the U.S. in 1999 and affects birds, humans, horses and other mammals. In humans, 80% of the cases are asymptomatic and 20% involve non-neuroinvasive illness. Less than 1% of cases result in conditions such as encephalitis which can cause paralysis and even death. There were nationwide epidemics of the virus in 2003 and 2012.

Adult mosquito surveys are conducted from May through October, testing them for mosquito-borne diseases. Field Techs focus first on standing water, where mosquitoes lay their eggs, taking samples to test for the presence of the virus. Spraying does not take place until an action threshold, a high enough percentage of positive mosquitoes indicating a threat of humans, is reached.

This August, high numbers of positives were detected in the Lehigh Valley so spraying began in hot spots. Safety precautions are taken for any application of pesticides. Public notices are sent out in advance to residents, people with immune problems, and apiaries. Spraying is limited to targeted areas and done at night to avoid affecting honeybees; streams, ponds and rivers are avoided to prevent contamination of waterways.

Successful control of the mosquito population requires community effort. Homeowners should drain any source of standing water on their property, including turning over buckets and pools and tossing unnecessary items and trash. Toys, pots, cans, tire swings and plugged gutters make for excellent mosquito breeding habitats. Mosquitoes can breed in as small a space as a soda bottle cap.

The Lehigh Valley may wish to consider the approach being used by a Google company called Verily to rid Fresno of mosquitoes carrying infectious disease. For the past two years, the City has sent white vans into problem neighborhoods to release, of all things, millions of mosquitoes. They are male mosquitoes. Male mosquitoes don't bite. And these particular mosquitoes are shooting blanks, i.e. are sterile. When they mate with a female, she is unable to produce offspring. The result is less mosquitoes.

After two years of Debug Fresno, Google reports a 95% reduction in mosquitoes carrying infectious disease in Fresno. A similar project in Innisfail, Australia, resulted in a 80% decrease in mosquitoes.