U.S. Lyme disease incidence rates in 2021, by state

In 2021, the U.S. states with the highest rates of Lyme disease were Maine, West Virginia, and Rhode Island. However, the states with the highest total number of Lyme disease cases were New Jersey, New York, and Pennsylvania. That year, there were a total of 1,510 cases of Lyme disease in the state of Maine, with an incidence rate of 110 per 100,000 population.

What is Lyme disease?

Lyme disease is caused by bacteria usually transmitted to humans through the bite of a tick. Lyme disease is the most common vector-borne disease in the United States, however it is much more prevalent in some states than others, with the upper Midwest and the Northeastern states most at risk. Symptoms of Lyme disease can vary and usually come in stages but may include a rash, fever, headache, stiffness in the joints, tiredness, and muscle aches and pains. Lyme disease is usually treated with antibiotics. In 2022, funding for Lyme disease from the National Institutes of Health (NIH) totaled around 50 million U.S. dollars.

Trends in Lyme disease

Although the number of Lyme disease cases per year fluctuates, over the past couple decades, the number of Lyme disease cases in the United States has steadily increased. Between 1996 and 2021, the highest number of Lyme disease cases was in the year 2009 when almost 30,000 cases were reported. The lowest number reported during this period was in 2020, with just 12,123. Cases of Lyme disease are much more common in the summer months of June and July as this is when people are most likely to encounter ticks. The risk of Lyme disease is expected to increase in the future as climate change contributes to an expanded habitat for ticks.