If you thought you were safe from Lyme disease because you don’t live in New England, where the tick-borne illness first appeared, think again. Now, 100 percent of the country — all 50 states plus the District — has residents who have tested positive for Lyme, a bacterial infection that can cause a wide variety of symptoms, including joint aches, fatigue, facial palsy and neck stiffness.

This news comes from a report from the clinical laboratory Quest Diagnostics, which analyzed the results of 6 million blood tests doctors had ordered to diagnose Lyme disease in their patients. The report found that Pennsylvania had the most positive cases last year: 10,001. The Pennsylvania tally, along with that of the six New England states — Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island and Vermont — accounted for about 60 percent of the country’s Lyme disease cases. Positive results grew by 50 percent in New England and by 78 percent in Pennsylvania from 2016 to 2017. However, the number of positive tests spiked in some areas not traditionally linked to Lyme disease. Florida, for instance, had 501 infections, up 77 percent since 2015. California had 483 people with positive test results — a 194.5 percent increase from 2015.

A telltale sign of Lyme disease is a bull’s-eye rash, but rashes with other shapes are common, too. Oral antibiotics cure most cases, especially when treatment starts early, but the infection can spread beyond the site of the bite if not treated. Some people have complained of symptoms that persist, and the National Institutes of Health is conducting research into chronic (or post-treatment) Lyme disease syndrome.

— Linda Searing