Mosquitoes

health

Montgomery County testing mosquitoes for West Nile virus after death

Following the confirmation of a West Nile virus related death and Montgomery County’s second possible case, the Precinct 3 Mosquito Abatement Team is on high alert as they continue to test mosquito samples.

On Friday, the Montgomery County Public Health District announced the death of a man in his 70s who lived in the 77381 ZIP code. While the man did have other medical conditions but the death was classified as a probable West Nile virus case. A woman in her 60s who lives in the 77382 ZIP code has been confirmed as the second case.

At this time in 2019, the county had no cases of West Nile virus, health officials said.


Cody Grimes, manager of projects and logistics for the Precinct 3 office, said the announcement of the death and second case did not prompt spraying in those ZIP codes. Grimes explained that due to the time to get the confirmation on the cases, crews had already responded to those ZIP codes when the mosquito sample returned positive.

He noted currently there are no West Nile positive samples in South County.

“We do spray when we get positive mosquito samples,” Grimes said, adding mosquito season is winding down. “There hasn’t been anything abnormal this year.”

West Nile virus can cause serious disease and is commonly spread by infected mosquitoes, according to MCPHD. People typically develop symptoms between three and 14 days after they are bitten. According to the CDC, approximately 80 percent of people who are infected will not show any symptoms at all.

Milder symptoms include fever, headache, body aches, nausea, vomiting and, sometimes, swollen lymph glands or a skin rash on the chest, stomach and back. These symptoms can last up to several weeks. Serious symptoms that account for less than 1 percent of those infected can include high fever, headache, neck stiffness, disorientation, coma, tremors, seizures or paralysis. These symptoms can last for several weeks and neurological effects may be permanent.

Anyone who develops symptoms of severe West Nile virus illness, such as unusually severe headaches or confusion, should seek medical attention immediately. However, the majority of milder illnesses improve on their own.

According to the CDC, the most effective way to avoid West Nile virus is to prevent mosquito bites. Avoid bites by using insect repellants, wearing protective clothing when outdoors and emptying standing water outside of your home.

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health

Artificial Light May Make Aedes Aegypti Mosquitoes ‘Abnormally’ Active At Night, Study Shows

KEY POINTS

  • Aedes aegypti mosquitoes are more active when there is natural light
  • A study found that Aedes aegypti mosquitoes bite twice as much at night when there is artificial light 
  • The study highlights how increasing levels of light pollution could impact transmission of diseases like dengue

Aedes aegypti mosquitoes, which are carriers of dengue and Zika viruses, are known to be active biters during the daytime, but a team of researchers has found that artificial lights can “abnormally” increase their biting behavior even at night.

Aedes Aegypti mosquitoes transmit various mosquito-borne diseases such as dengue fever, chikungunya, yellow fever and Zika fever. The species mostly bite in the early morning and in the afternoon hours when there is light, but what happens when they are exposed to artificial lights at night?

To find out, a team of researchers conducted an experiment wherein the study’s first author, Samuel S. C. Rund of the University of Notre Dame’s Department of Biological Sciences, let mosquitoes bite him under certain conditions including during daytime, at night, and at nighttime while exposed to artificial light. They then measured the mosquitoes’ blood-feeding behavior.

As expected, the mosquitoes fed more during the daytime and less at night. However, mosquitoes that were exposed to artificial light at night were actually twice as likely to bite compared to those not exposed, a news release from the University of Notre Dame said.

This shows that mosquitoes that feed during the daytime tend to bite more at night when there is artificial light.

Aedes aegypti mosquitoes Aedes aegypti mosquitoes are seen at the Laboratory of Entomology and Ecology of the Dengue Branch of the U.S. Centers for Disease Control and Prevention in San Juan, Puerto Rico, March 6, 2016. Photo: Reuters

“This is potentially a very valid problem that shouldn’t be overlooked,” study co-author Giles Duffield, also of the University of Notre Dame’s Department of Biological Sciences, said in the news release. “They live and breed in the vicinity of houses, so the chances of Aedes aegypti being exposed to light pollution are very likely.”

Aedes aegypti mosquitoes are considered “container-inhabiting” mosquitoes, the University of Florida (UF) explains, because they often breed in items that are commonly seen in or around a house, such as spare tires, drainage ditches, untreated swimming pools and unused flower pots. 

“They thrive in urbanized areas, in close contact with people making them an exceptionally successful vector,” the university in a feature.

The Notre Dame team said their study “highlights the concern that globally increasing levels of light pollution could be impacting arboviral disease transmission, such as dengue fever and Zika, and has implications for application of countermeasures for mosquito vector control.” 

The researchers are studying the relationship between artificial light and Aedes ageypti and trying to understand whether there is a genetic factor to the mosquitoes’ biting behavior since not all of them are willing to bite at night even with the lights, the news release said. 

The study is published in The American Journal of

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