Diseases spread by mosquitoes and ticks are on the rise in the United States, both in geographic coverage and in numbers of victims.
There is reason to believe a warming climate is playing a role in these trends, but that is a far cry from assigning all of the blame to climate change. There is a statistical correlation with an increase in tick and mosquito borne diseases and warmer temperatures. In terms of absolute proof, though, correlation does not prove causation.
Let’s look at the trends, with data supplied by the Centers for Disease Control and Prevention. Click here to see the most recent epidemiological incidence map for Lyme Disease, from 2016. Now, compare the incidence and coverage with that of 2001.
Reported case trends from 1996 to 2016:
It should be noted that epidemiologists believe there is still massive underdiagnosis of Lyme disease. About 35,000 cases are diagnosed and reported annually, but CDC estimates that the real number of incidence is closer to 300,000 cases. Some victims develop only minor symptoms and largely ignore them with no diagnosis or treatment, which can be a dangerous choice. We don’t have the space for a complete discussion of Lyme disease symptoms and treatment, but here’s a CDC link on proper tick removal technique. You can find signs and symptoms here and guidelines for treatment here.
Not all insect vector-borne rates of incidence have a demonstrable tie to a warming climate. West Nile Virus is one example. However, there is a somewhat more compelling link to be made for the increased incidence and geographic spread of tick-borne diseases and at least some relationship to warming and longer growing seasons. Moreover, New York State now ranks near the top.
Other factors, according to the CDC, include land use; socioeconomic and cultural factors (i.e. more hiking, more exposure on marginal lands); pest control; access to health care; and human response to disease threat.
Mosquito control undertaken by counties and municipalities using EPA-registered larvicides and insecticides vary in efficiency, depending on budgetary constraints and community response (or resistance) to those efforts. Sometimes, public support grows when evidence of the West Nile Virus shows up in traps and, worse, with human cases. As individuals, we all need to eliminate as much standing water on our property as possible to reduce breeding grounds.
Control of tick populations is far more difficult and is seldom undertaken by counties and municipalities. On your own property, opening some shaded brush areas near walkways to more sunlight and less dampness can reduce populations. For individuals, DEET is still the main insect repellent of choice, though there are some alternatives. Its efficacy and safety have long been demonstrated, when properly used. Protective clothing may not sound appealing in hot weather, but long-sleeved shirts, hats and tucked-in long pants really do make tick attachment far less likely.
“Checking for ticks” is a must when walking through the brush, and clearing tall growth and brush away from walkways is advisable. Consumer Reports recommends cutting grass to a shorter length near walkways, even if it’s not the best thing to do for a lush lawn. In addition to using repellents such as DEET on our skin, treating our clothing and gear with permethrin (which CDC notes is a highly effective insecticide and repellent) can make a big difference. This is also recommended by Consumer Reports.
If you’re craving more detailed information on these preventative measures, check out this link from CDC.
By the way, the author is aware ticks are not insects, so hold the emails. Locally, our own Cornell Cooperative Extension has great biological expertise to offer homeowners.