Climate Change and Arthropod-borne Diseases

by Tom Ellis

ALBANY, NY: Bryon Backenson of the NYS Health Department DOH) spoke at the October 19 SPB dinner about climate change and arthropod-borne diseases. Mr. Backenson is a research scientist and Director of Investigations and Vector Surveillance Control in the DOH Bureau of Communicable Diseases Control (BCDC). He is also an assistant professor in the Department of Epidemiology and Biostatistics at the University at Albany’s School of Public Health.

Mr. Backenson is also chair of the Clifton Park open space committee. I heard him speak at the August 15 Climate, Weather, Data: Protecting Our Crops and Landscapes conference in Voorheesville and was pleased he agreed to speak with SPB.

He began saying about seventy communicable diseases are reported to DOH, the BCDC investigates them and tries to limit their spread, and he detects pathogens and helps prevent their spread. The BCDC conducts surveillance and receives reports, educates the public and health providers, does research in laboratories and searches data for trends, and vector control — knocking out mosquitoes.

Mr. Backenson spoke about the importance of correct tick removal. He said the more you annoy a tick the more it salivates and infects you. He urged people to remove ticks pulling them straight out with fine point tweezers.

Mr. Backenson said there are many vector-borne diseases in New York. These include six or seven tick-borne diseases including Lyme Disease; many mosquito-borne diseases including West Nile Virus, Eastern Encephalitis, Dengue Fever, Yellow Fever; and many louse- and flea-borne diseases. He said Yellow Fever is now raging in Africa and Zika has little health impact on the already-born but can have considerable impacts on the unborn.

He said there is much less insect control in New York with pesticides than years ago and increased hiking leads to more tick exposures. Lyme Disease, he said, has been moving north and west across New York; thirty years ago, about ninety percent of the reported cases were in Suffolk, Nassau, Putnam, Westchester, and Rockland counties; the total in those counties remains about the same today while their proportion of the state total declines.

“We tend to think of climate change in a vacuum,” he said. A one degree temperature increase may lead to a spread of one vector to new regions but a predator may also move with the vector species. “Predicting climate change impacts,” he said, “is not easy due to it’s complicated impacts.”

He insisted that we must have guidelines in place when we count things and there is considerable uncertainty if disease symptoms experienced by a person are caused by Lyme Disease.

New York has the most Zika cases of any United State due to New York City being a major travel hub to and from Central and South America. He said Puerto Rico has 26,000 cases or ninety-eight percent of locally acquired cases in the United States. New York has 838 reported cases with 620 of these in New York City.

Two mosquitoes are associated with Zika transmission; Aedes aegypti, which is tied to human exposures, a skittish bug that can infect five or six people before “getting a belly full of blood;” and Aedes albopictus (the Asian Tiger Mosquito), which feeds on many species. Aedes albopictus is the one we see in New York, and is not as potent a vector as Aedes aegypti.

He said all mosquitoes must find some way to survive the winter as larva, eggs, or adults, or they die in sustained cold weather. New York has about seventy-five mosquito species and each has separate characteristics. Climate play a big role in their lives.

Of the approximately seventy-five ways to catch mosquitoes, DOH primarily uses five. He said individual mosquitoes rarely travel more than 200 yards from where they are born.

He said he has worked on and off at DOH for sixteen years. The BCDC receives strong financial and political support from the state, his bureau is good at what it does, and must react to disease outbreak when they occur. BCDC works with many other government agencies and the University at Albany School of Public Health.

The big Zika concern today is in Asia, especially China and India. Good sanitation and screens on windows limit Zika incidence in the US. He said he does not expect there will be tens of millions of Zika cases in South and Central America. New bug-borne diseases occur in the world on average about every three to four years.

If Zika infects a person, the body will repel it; if a woman gets pregnant years after a Zika exposure, the baby will not be Zika-impacted.

He said ticks die out in dry conditions; snow cover keeps humidity high underneath allowing tick survival.

Tim Truscott said there are many more mosquitoes in his Albany neighborhood than twenty-fives years ago and far fewer night hawks.


Published in November/December 2016
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