Reported cases of tickborne disease — U.S. states and territories, 2004–2016


A Facebook friend posted a photo of his adult son’s nasty spider bite over the weekend. The wound came from one of only two venomous spiders in the U.S. that cause severe reactions (the black widow and the brown recluse), sending him to the hospital emergency department and keeping him there for a day. Amanda Gardner reminds us that most other spiders don’t bite at all, and when they do, they aren’t venomous. Simple home therapy is all that’s needed:

Wash the area with soap and water and apply an antibiotic ointment. Then rest, use a cold compress to reduce any pain and swelling, and elevate your arm or leg if that’s where you were bitten. Over-the-counter pain relievers and antihistamines can help as well.


Gardner looks at other biting insects that are often no more than summertime irritants. (Spiders, by the way, are arachnids, not insects, and are enormously beneficial to your home and garden when they aren’t scaring the heck out of you.) Mosquito bites are probably the most common bites seen, and while they can carry severe and sometimes life-threatening diseases like malaria, dengue, yellow fever, West Nile, Zika, and several others, they typically cause nothing more than raised pink welts that itch like crazy. Cold compresses and perhaps a little Calamine lotion should take the itch away. Bites from flies, fleas, bedbugs, chiggers, lice, and ants seldom cause anything worse than rashes that itch. (Of course, we all should remember that the bubonic plague (“Black Death”), which spread through Europe, Asia, and Africa in the 14th century and killed upwards of 50 million people, was transmitted by the lowly flea.) A study last month from the Centers for Disease Control and Prevention shows a rise in vector-borne diseases in the United States. Between 2004 and 2016, most vector-borne diseases were transmitted by mosquitos and ticks (77%):

A total 642,602 cases were reported. The number of annual reports of tickborne bacterial and protozoan diseases more than doubled during this period[…] Lyme disease accounted for 82% of all tickborne disease reports during 2004–2016. The occurrence of mosquitoborne diseases was marked by virus epidemics. Transmission in Puerto Rico, the U.S. Virgin Islands, and American Samoa accounted for most reports of dengue, chikungunya, and Zika virus diseases; West Nile virus was endemic, and periodically epidemic, in the continental United States.


Also worrisome is the fact that nine new diseases emerged during this period:

Overall, from 2004 to 2016, there were nine insect-spread diseases reported for the first time in the United States and U.S. territories, including Zika, chikungunya, Heartland virus, Bourbon virus and more.


Alexandra Sifferlin explains that several factors, including climate change, are responsible for the rise in vector-borne infections:

The reason for the increase in diseases spread by mosquitoes largely has to do with the fact that people and goods are traveling and accessing different parts of the world more now than in the past. “All someone needs to do is pick up one of these viruses and fly back to the Untied States,” says Petersen. “If a local mosquito bites them, it can cause an outbreak. That’s what happened with Zika.” Other diseases like West Nile virus can be affected by climate and weather, with warmer weather coinciding with outbreaks.

The rise in diseases spread by ticks could be partly due to people living in wooded spaces where there are more deer—a popular host for ticks. With less farmland and more suburban living, neighborhoods are developing in places where ticks are common. CDC experts say the geographic range of ticks that spread disease has steadily grown over the past 20 years.


Every county of Pennsylvania has now been impacted by the spread of Lyme disease carried by deer ticks. (Like spiders, ticks are also arachnids.) With a wetter and warmer climate forecast for Pennsylvania in the next several years and decades, the impact of Lyme disease will be felt more vividly as the tick’s lifecycle and habitat changes. If a tick happens to avert your careful surveillance and bites and feeds from your or your child’s skin, early removal is extremely important, says Amanda MacMillan:

When a tick bites into a human’s or animal’s skin and begins feeding, it can transmit bacteria, viruses or parasites. For some illnesses, like Lyme disease, it takes 24 to 36 hours for the harmful bacterium to be passed to the host[…]


Fine-tipped tweezers are the best tools for removing a feeding tick, whose mouth parts can become practically cemented to the skin. Trying to suffocate the tick by smothering it with vasoline or lighting it with a match, as some old remedies suggest, will likely not be successful and may even be dangerous. Grab the tick as close to the skin as possible, without squeezing on the abdomen, and, without yanking or twisting, pull it straight out with steady and even force. Don’t be alarmed if you don’t get the whole tick:

If part of the tick stays in your skin after you pull it out with tweezers, try not to worry too much about it. “Treat it with alcohol to make sure it’s sterile, but mouth parts themselves will not cause infection,” says Gangloff-Kaufmann, “and your skin will work them out just like it does a splinter.”


Clean the area with a cotton ball soaked in rubbing alcohol and flush the tick down the toilet. (There is no need to save the tick; pediatricians run tests on tykes, not ticks.) If you think the tick was attached for longer than 24 hours, or you aren’t sure, call your doctor’s office during regular office hours for further instructions. (Tick bites are not emergencies.)