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Warming planet means more mosquito-borne disease

Kathy Aney

East Oregonian

Published on July 20, 2018 4:54PM

Staff photo by E.J. HarrisMosquioto expert Sascha McKeon spend three years in the Brazilian Amazon and even discovered a previously unknown mosquito species - the anopheles rickwilkersoni.

Staff photo by E.J. HarrisMosquioto expert Sascha McKeon spend three years in the Brazilian Amazon and even discovered a previously unknown mosquito species - the anopheles rickwilkersoni.

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Staff photo by E.J. HarrisA helicopter is used to disperses the larvicide, VectoBac G, over wetlands in the Power City Wildlife Area to control mosquito populations on Thursday north of Hermiston. The helicopter is contracted by the West Umatilla Mosquito Control District.

Staff photo by E.J. HarrisA helicopter is used to disperses the larvicide, VectoBac G, over wetlands in the Power City Wildlife Area to control mosquito populations on Thursday north of Hermiston. The helicopter is contracted by the West Umatilla Mosquito Control District.

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Staff photo by E.J. HarrisA ground crew at the West Umatilla Mosquito Control District fills a aerial application bucket system with the larvicide, VectoBac G, on Thursday in Hermiston.

Staff photo by E.J. HarrisA ground crew at the West Umatilla Mosquito Control District fills a aerial application bucket system with the larvicide, VectoBac G, on Thursday in Hermiston.

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The deadliest creature in the animal kingdom doesn’t have teeth or claws — it’s smaller and far more benign looking than bear, boa constrictor or shark.

“The number one most dangerous animal in the world is the tiny, tiny mosquito,” said mosquito expert Sascha McKeon. “Mosquitos are the worst vectors. They transmit bacteria, viruses and parasites like protists and nematode worms. Mosquitoes can carry multiple infectious agents.”

Mosquitoes can pass along malaria, Dengue fever, chikungunya, encephalitis, yellow fever, West Nile virus and zika, among others. Now, thanks to climate change, some of these ailments could someday come to a neighborhood near you.

McKeon spent three years as a field researcher in the Brazilian Amazon and even discovered a previously unknown mosquito species — the Anopheles rickwilkersoni. The Blue Mountain Community College biology instructor spoke Tuesday at the monthly Science Cafe hosted by the Eastern Oregon Climate Change Coalition (EOC3) at the Prodigal Son Brewery & Pub.

McKeon likes to refer to a mosquito researcher as a cross between Indiana Jones and Buffy the Vampire Slayer. Instead of gold, however, mosquito researchers chase down larval breeding sites and genetic information.

McKeon flashed on the screen a chart showing numbers of people killed by various animals. Sharks kill about 10 people in the world each year. Crocodiles kill 1,000. Snakes kill 50,000. Humans murder around 425,000.

The mosquito stood alone in its lethality.

“About 725,000 deaths a year can be attributed to mosquitoes worldwide,” McKeon said.

The mosquitoes transmitting all those viruses and diseases aren’t found only in distant Africa or South America, McKeon said. They already live right here in the United States.

“There are 3,500 different species of mosquitoes,” McKeon said. “They span all seven continents. There are mosquitoes that live in Antarctica. They are everywhere.”

She ticked off the names of the three main types of mosquitoes on the planet — Culex, Aedes and Anopheles — and said all reside here. The Culex is brown and bland — the unshowy, girl-next-door mosquito. Aedes mosquitoes, such as the Asian tiger mosquito, are black with white stripes. The Anopheles, the type that transmits malaria, is black and sleek with knee-high white stockings.

So why isn’t the U.S. swamped by deadly mosquito-borne diseases?

“What’s really holding back the diseases is that pathogens need a certain temperature to transmit,” McKeon said.

She said mosquitoes can go full-throttle in places where the temperature is 84 degrees and higher year-round like the tropics. As long as we continue to have seasons, mosquitoes will die off and new uninfected batches will emerge, she said. But if we become like the tropics, then there will be no die-off.

“Lets flash forward 60 years from now,” McKeon said. “If our climate estimates go as predicted. By 2080, it’ll be 84 degrees almost year-round (in much of the U.S). This will be the new tropics. Oregon will have pockets.”

Oddly, malaria has visited us before. McKeon flashed on the screen a photo of the Centers for Disease Control in Atlanta.

“This was not built to be the CDC,” she said. “It was built (in 1942) to be the Office of Malaria Control.”

The office was placed in Atlanta rather than Washington, D.C., because the South had the most malaria problems. The National Malaria Eradication Program sprayed, drained mosquito breeding sites and used other methods to eliminate malaria from the country by 1949.

It will likely return as global temperatures rise.

Ticks are already spreading farther north and McKeon attributes that to longer, warmer springs that lengthen summer, giving ticks an increased chance of survival going into winter. Rocky Mountain spotted fever, which is transmitted by certain ticks, was diagnosed this summer in Morrow County.

McKeon isn’t all gloom and doom. She hopes mankind will find a way to combat climate change. There are ways to control mosquitoes and the arsenal is growing.

One promising method is the sterile insect technique. The idea is to release irradiated male mosquitoes. After mating with them, the females lay sterile eggs. It takes a lot of energy for mosquitoes to mate and they have to wait a month to build up enough energy for another attempt. The population slowly decreases.

McKeon doesn’t believe mosquitoes should be totally obliterated from the face of the earth, even if it was possible.

“Do we really want to eradicate them?” she asked. “They are an integral part of several ecological food chains. What about the birds and fish that feed on them? We would be taking away a major source of protein for them.”

But the point is moot.

“Mosquitoes have always been around,” McKeon said. “Mosquitoes are older than we are. They’ve been around over 100 million years. The numbers are rising. We haven’t controlled them and we haven’t figured out how to live in harmony with them just yet.”

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Contact Kathy Aney at kaney@eastoregonian.com or 541-966-0810.





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