Brad Paisley's 2007 song "Ticks" includes the not-so-enticing pick-up line "I'd like to check you for ticks." Yet it could be a healthy start to a new relationship, especially here: Pennsylvania led the nation in Lyme disease cases last year and New Jersey came in third.

In addition to carrying Lyme disease, ticks also carry Powassan virus, a rare disease that is now found in both states. There are many others on the lists of tick-borne illnesses put out by the World Health Organization and the Centers for Disease Control and Prevention.  A number of them are grouped as spotted fever  and referred to as rickettsioses. It's caused by the bacteria named for University of Chicago pathologist Howard Ricketts, who discovered the link in 1906.

Want more history? Research into tick-borne diseases in the United States, including the deadly Rocky Mountain spotted fever began at the turn of the 20th century. The state of Montana led the way. Check out this picture of Dr. Robert Cooley, of the Montana State Board of Entomology, with his collection of ticks from around the world.  The United States Public Health Service began the Rocky Mountain Laboratory in Hamilton, Mont., and took over the Board of Entomology in 1932.  During World War II, the laboratory produced vaccines against a number of diseases and after the war it became part of the National Institute of Health and is now located in the NIH's  of the National Institute of Allergy and Infectious Disease. Basic research investigations into vector-borne diseases continue in the facility, which now consists of five laboratories.

Tick diseases, pardon the expression, continue to hang on. (Technically the ticks grasp the skin, cut into it, insert a feeding tube and consume a blood meal.) Preventing ticks from attaching to you and others involves using DEET a chemical that repels but does not kill insects.  DEET raises safety issues in the eyes of some consumers but the Environmental Protection Agency reviewed its safety in 2014 and concluded that "normal use does not present a health concern to the general population, including children."

Even with DEET, though, you need to shower after outdoor activities, and, of course, conduct tick checks on yourself, on family members, and on your pets.  What to do? Here's the CDC's How to Remove a Tick guide – and a video from Tick Man Dan

Janet Golden focuses on the history of medicine and science. Her forthcoming book is "Babies Made Us Modern: How Infants Brought Americans into the 20th Century."