Thursday, December 22, 2022

Science Advances: A Widespread Super–Insecticide-Resistant Aedes aegypti Mosquito in Asia










#17,188

When it come to deadliest creatures on earth; sharks, snakes, and even humans pale in comparison to the lowly mosquito, which serves as a vector for an array of deadly diseases (Malaria, Dengue, WNV, EEE, Zika, etc.) that kill well over 1 million people each year. 

Next to proper sanitation and effective water treatment, the control of mosquitoes has probably done more to save lives than any other non-pharmaceutical intervention. 

But, as I wrote a dozen years ago in From the `Nature Bats Last’ Deptas a soon as somebody invents a better mousetrap, nature will begin to work on making a better mouse. 

In 2010, the immediate concern was that our most effective mosquito repellent DEET, or N,N-Diethyl-m-toluamide  (a name that, for some reason, never really caught on with the public), was beginning to lose some of its effectiveness. 

A year later, we saw a cautionary report from Declan Butler On Growing Mosquito Insecticide Resistance, whose Nature News article Mosquitoes score in chemical war describes how growing resistance is threatening global malaria-control efforts.

A 2014 PLoS One Study Insecticide Resistance Status of United States Populations of Aedes albopictus and Mechanisms Involved noted some pockets of mosquitoes resistant to DDT and malathion in both Florida and New Jersey.  

While in 2016 we reviewed an Interim guidance document for entomologists from the WHO: Monitoring & Managing Insecticide Resistance in Aedes Mosquito Populations,

As I noted at the time, adaptation is the linchpin of evolutionary survival, making man's victories against bacteria, viruses, and other pests fleeting at best.

Yesterday researchers from Japan's NIID (National Institute of Infectious Diseases) published a lengthy paper in Science Advances, which documents the widespread detection of super-insecticide-resistant mosquitoes in Vietnam and Cambodia. 

While this isn't the first detection of this genetic trait, it is the most intense, and widespread to date. Due to its length, I've only reproduced the abstract below.  Follow the link to read it in its entirety.  I'll have a postscript when you return. 


SHINJI KASAI, KENTARO ITOKAWA , NOZOMI UEMURA , AKI TAKAOKA , SHOGO FURUTANI, YOSHIHIDE MAEKAWA, DAISUKE KOBAYASHI , NOZOMI IMANISHI-KOBAYASHI, MICHAEL AMOA-BOSOMPEM , AND OSAMU KOMAGATA

Aedes aegypti (Linnaeus, 1762) is the main mosquito vector for dengue and other arboviral infectious diseases. Control of this important vector highly relies on the use of insecticides, especially pyrethroids. The high frequency (>78%) of the L982W substitution was detected at the target site of the pyrethroid insecticide, the voltage-gated sodium channel (Vgsc) of A. aegypti collected from Vietnam and Cambodia. Alleles having concomitant mutations L982W + F1534C and V1016G + F1534C were also confirmed in both countries, and their frequency was high (>90%) in Phnom Penh, Cambodia.
 
Strains having these alleles exhibited substantially higher levels of pyrethroid resistance than any other field population ever reported. The L982W substitution has never been detected in any country of the Indochina Peninsula except Vietnam and Cambodia, but it may be spreading to other areas of Asia, which can cause an unprecedentedly serious threat to the control of dengue fever as well as other Aedes-borne infectious diseases.

          (Continue . . . )

For most of the 20th century, the control of mosquitoes - and mosquito borne diseases - has been a remarkable success story, particularly in North America and Europe.  But in 1999 the West Nile Virus (likely brought in by a traveler to New York City) arrived, and quickly spread across the nation. 

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Today it is endemic across all of North America, and causes tens of thousands of mild illnesses, and hundreds of deaths, each summer. Since then : 
Anything that erodes our ability to control mosquitoes - such as the spread of insecticide-resistant breeds - poses a genuine public health concern.  

Which is why yesterday's report may eventually have global significance.