By Carole Upshur, Bronxville Green Committee
Jul. 29, 2020: Human pandemics are not new, and pandemics arising from viruses or bacteria linked to animals (zoonoses) are also not new.
The common flu, AIDS, rabies, and bubonic plague all have animal origins. Sixty to seventy percent of new infectious diseases come from animals.
Unfortunately, as bad as COVID-19 is, it is probably not the last scary infectious disease we will see in the near future.
Climate Change Affects Our Health
Almost all scientists agree that the burning of fossil fuels has drastically increased CO2 in the atmosphere, creating a “greenhouse effect” that results in a warming planet. Deforestation and many industrial agricultural practices also contribute to rising CO2.
Climate change affects our health beyond the obvious problems of heat, drought, fire, and increasingly extreme weather events. It is, therefore, important to tackle climate issues while also fighting the coronavirus pandemic.
-A warming climate increases the range of insects and other species that can bring once tropical diseases to areas like Westchester.
-A warming climate and population growth disrupt the ability of subsistence farmers to grow crops, resulting in their migration into wilderness areas, where they clear forests and put humans in contact with wild animals that carry diseases not normally transmitted to humans.
-As wilderness areas decrease, wild animals are forced into populated areas to find food, increasing their contact with humans.
-Food insecurity caused by stresses on water supplies and crops increases the hunting and foraging of wild animals for food.
Climate-related Diseases Have Reached Westchester
The most prevalent new diseases in our area are related to the tick population, including ticks that have migrated here from farther south.
Of the thirty tick species in New York State, four transmit disease to humans: the Deer or Black-legged tick, the American dog tick, the Lone Star tick, and the Woodchuck tick.
Ticks can be carried by many forest animals, including mice, chipmunks, squirrels, rabbits, fox, and deer, as well as animals like cows and dogs. For example, the Deer tick, which transmits Lyme disease, has a life cycle that involves three hosts. It starts with mice, which transmit the pathogen to the tick larvae, then other rodents at the nymph stage, and then the deer at the adult stage.
According to the New York State Department of Health, during the last few years, there has been a 65% increase in adult ticks carrying Lyme bacteria in Westchester.
But Lyme disease is only one of the tick-borne illnesses. Ticks can carry parasites, bacteria, and viruses that cause other diseases, including Babesiosis, Anaplasmosis, Ehrlichiosis, Rocky Mountain Spotted Fever, Tick Born Relapsing Fever (TBRF), and Powassan virus.
Recent media reports mention anaplasmosis as a growing tick-caused disease in the Hudson Valley and Long Island that mimics some COVID-19 symptoms, such as aches and fevers, without the rash common to Lyme disease. Anaplasmosis and Ehrlichiosis can be easily treated with a common antibiotic, but it’s essential to see a health-care professional soon after exposure and obtain a blood test to check for antibodies.
The New York State Department of Health runs an ongoing program that collects and analyses ticks for diseases and releases annual reports.
In 2019, ticks collected in Westchester carried the following diseases: 56% Lyme disease, 4% Babesiosis, 6% Anaplasmosis. The bacteria causing TBRF was 0% in Westchester County in 2019, although it was recorded in 4-10% of tick samples in prior years.
Tick-borne Illnesses Are Spreading
Tick-borne illnesses have doubled nationally since 2004, and seven new tick-borne pathogens have been identified.
A main cause is human intrusion into wild habitats and destruction of habitat for many species, including predators that hunt smaller mammals like mice. Mice tend to flourish in disrupted habitats because they have learned to feed on garbage and nest in proximity to humans.
In Westchester County, lower numbers of opossums due to loss of habitat has also led to more ticks. Opossums attract ticks to their fur but are effective in removing them through grooming. They eat up to 4,000 a week, according to a study by forestry scientist Richard Ostfeld from the Cary Institute of Ecological Studies in New York.
He also examined other species of animals common in the Hudson Valley and found that mice were the least effective groomers; they carry a lot of the tick population.
What Other New Disease Risks Do Westchester Families Face?
Another major vector for human disease is mosquitoes. Fortunately, according to the National Center for Biotechnology Information, conditions in the Northeast are not ideally suited for their breeding.
Dengue fever and Zika, which are carried by different species of mosquitoes, are spreading throughout the southern U.S., and the National Institute of Health (NIH) has reported cases of Dengue fever as close as Philadelphia. Over the next few years, such diseases could reach us.
New York City was the site of the first U.S. outbreak of West Nile virus, a mosquito-borne disease that transmits through birds. While there have been no recent cases in New York, West Nile is the leading cause of mosquito-borne illness in the U.S., primarily in Florida, the Southwest, California, and some midwestern states. Just recently, West Nile was detected in mosquitos in the Chicago suburbs.
West Nile virus was first detected at the Bronx Zoo in 1999 when crows and zoo birds started dying. As dead birds proliferated around the city, a mysterious human infection caused fever, confusion, weakness and was, in some cases, fatal. The death rate is about 5%, five to ten times the current coronavirus mortality rate. Robins and crows, which abound in urban areas and other disrupted habitats, are particularly good spreaders. In regions with larger and more diverse bird populations, the danger of West Nile is lower.
According to the New York State Department of Health, Eastern equine encephalitis (EEE) is another rare mosquito-borne illness that has reached upstate. This viral illness has no known treatment, and of the five confirmed cases in the state, none survived. There has not been a confirmed case since 2011.
Certain other circulating zoonotic viruses pose low-level threats. These include SARS CoV-1, Middle East Respiratory Syndrome, swine flu, and various avian and bird flu types. Some of these migrated from the wild into domestic farm animals and pose a constant threat if they are not carefully monitored. Human disease can also be caused by poor handling of meat in the supply chain and the unsafe storage of animal waste.
Bats Can Carry Deadly Viruses
Many viruses that can be caught by humans are endemic to bat populations.
Bats are not necessarily common in cities; however, intrusions into wilderness areas and the appetite in China and Africa for wild meat or medicinal cures from wild animals, increases human-bat contact.
The international wildlife trade and wild meat sold at wet markets, where various species are kept in cages near each other and slaughtered on the spot, provide ample opportunity for humans to contact airborne and blood or feces-borne pathogens.
The best theory about the origin of our current coronavirus is that it came from horseshoe bats trapped for food in central China and brought to the Wuhan wet market. It could also have come from bats brought to China from other areas of Southeast Asia.
Bats have adapted to tolerate high viral loads without suffering autoimmune reactions, and because flying raises their temperature, the viruses they attract also tolerate high temperatures.
So when humans develop a high fever to combat the same virus, it has no ameliorative effect. It’s difficult for humans to mount an immune response that is effective in reducing the virus.
How Can We Protect Ourselves?
In the last one hundred years, we have had a great run of success in controlling human infectious, so much so that many of us have taken our ability to fight disease for granted. The current coronavirus pandemic has been a shock and a wake-up call.
Vaccination provides the first line of defense. It’s troubling that lower vaccination rates have recently provoked outbreaks of measles in New York, and that polio and even smallpox are popping up in other countries.
Coronavirus reminds us we are just another mammal on the earth and not immune from the life and death struggles of all creatures.
There are obvious and simple preventive steps to avoid the common tick and mosquito-borne illnesses here in Westchester. These include
-wearing long-sleeved clothing,
-using insect repellant,
-doing tick checks of children and dogs,
-keeping current with vaccinations, including flu, which many of us don’t take seriously enough.
The ultimate solution lies in our coming to grips with climate change. To prevent being overwhelmed by ever more frequent and possibly deadly new zoonotic diseases, we need to face the hard reality of our human impact on the natural world.
We need to change the way we produce our energy and raise our food so that they do not threaten the very planet we rely on for sustenance.
As we work to address those challenges, we also need to invest in public health and scientific infrastructure—including local monitoring such as is currently going on in New York regarding ticks and mosquitos--to detect known and new pathogens.
Monitoring commercial agriculture animals in the U.S. and abroad is also important since some pathogens from the wild infect pigs, cows, and poultry, which in turn pass disease on to humans.
Looking at the genetic make-up of the 1918 flu virus, for example, suggests it might have passed through pigs before infecting humans.
We also need to support monitoring, surveillance, and better controls in other countries, particularly those that rely on wild animals for human consumption.
Unfortunately, last year a U.S. AID program that was doing just such monitoring was defunded, and recently the U.S. withdrew its financial support for the World Health Organization.
Budgets for disease identification by the Centers for Disease Control (CDC) have been cut 40% in the last decade (Live Science, 2013). This month, the American Public Health Association reported that over 55,000 U.S. state and local health workers had been cut since 2010 due to a lack of funding. Such zoonotic surveillance programs are critical in detecting and preparing for the next pandemic disease.
Note: Carole Upshur, EdD, is Professor Emeritus, Department of Family Medicine and Community Health, University of Massachusetts Medical School, and a member of the Bronxville Green Committee.
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