Lyme Disease Facts and Statistics: What You Need to Know

Lyme disease is an illness transmitted by ticks that carry the Borrelia burgdorferi bacterium. It is the most common vector-borne illness in the United States and affects an estimated 476,000 Americans yearly.

About 35,000 new cases are reported each year, although experts believe cases are underreported and undercounted. This would account for the large difference in reported cases vs. the estimated number of infections.

This article offers Lyme disease facts and statistics, including risk factors, incidence, screening, and detection.

Lyme Disease Overview

Lyme disease symptoms are not always obvious, and they vary, making diagnosis tricky. However, a bull's-eye skin rash is the most prominent characteristic of Lyme disease. Other symptoms include:

• Fever
• Headache
• Facial paralysis (with drooping usually on one side of the face)
• Fatigue
• Joint pain

Lyme Disease

How Common Is Lyme Disease?

Lyme disease is more common in certain geographic locations, where ticks that carry the disease are found. In the United States, the most common areas for contracting Lyme disease are:

• New England
• Mid-Atlantic states, including Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and Washington, D.C.
• Wisconsin
• Minnesota
  

Lyme disease incidence is increasing. In 1996, there were 16,455 confirmed cases; in 2019, there were 23,453 confirmed cases along with 11,492 probable cases.

Lyme Disease by Ethnicity

According to a study on health disparities associated with Lyme disease in the United States, the incidence of Lyme disease was highest in areas of socioeconomic advantage. People who reported Lyme disease were more likely to be White and college educated, and less likely to live below the poverty line. The researchers noted that other studies have reported both similarities and differences to these findings regarding tick-borne diseases in relation to socioeconomic factors.

Researchers have found that Black Americans tend to be diagnosed with Lyme later than White Americans. One study examined the differences in Lyme disease diagnosis between Black and White participants. In a sample of Medicare beneficiaries, researchers found that 34% of Black participants were diagnosed when they had advanced neurological symptoms compared to 9% of White participants who waited until this time.

Lyme Disease by Age and Gender

Lyme disease affects children more than adults. After children, middle-aged adults are most commonly infected.

One study reviewed 25 years of data to evaluate Lyme disease's changing age and sex distributions. Researchers found that the consistent peak in disease cases was among children ages 5 to 9. This led researchers to theorize that age-related behavior and interaction with tick habitats may make this age group more susceptible to Lyme disease.

The next highest age group was the so-called baby boomer generation of people born roughly from 1946 to 1964. Researchers suspect that the proportion of cases in this generation may have more to do with the size of this age group rather than outside risk factors. In other words, there are more people in this age group and, therefore, more cases.

In addition, Lyme disease affects males more than females. The same study also reported that incidence rates were significantly higher among males vs. females in most age groups.

Causes of Lyme Disease and Risk Factors

While ticks transmit Lyme, not every tick bite results in the disease. The most significant risk factor is how long a tick stays attached—if you do not remove a tick within 48 hours, the risk of contracting Lyme disease increases.

Risk factors for contracting Lyme disease include:

• Geographic location (mid-Atlantic and upper midwestern states)
• Exposure to tick habitats (wooded and grassy areas)
• Exposed skin
• Sitting in grass
• Brushing against trees, grasses, and brush

What Are the Mortality Rates for Lyme Disease?

Most people fully recover from Lyme disease with antibiotic treatment. However, many people not diagnosed and treated early may develop complications, some of which could be life-threatening. Late Lyme disease may result in the following:

• Arthritis
• Nervous system complications (nerve paralysis and meningitis)
• Heart rhythm irregularities
• Problems with memory, sleep, fatigue, and headaches

Surveillance data between 1985 and 2019 found 11 cases of fatal Lyme carditis (Lyme disease that infects the heart) worldwide. A review of death certificates between 1999 and 2003 listed Lyme disease as a rare cause of death.

During the review period, 96,068 cases of Lyme were reported to the Centers for Disease Control and Prevention (CDC). By contrast, in the United States, only 23 death certificates listed Lyme disease as an underlying cause of death.

Early Detection and Prevention

If you know a tick has bitten you or you have symptoms that indicate Lyme disease, diagnosis and treatment are essential. The sooner you receive treatment, the better your chances of a full recovery.

If you are experiencing symptoms, there is a two-step blood test to check for Lyme disease antibodies: An enzyme-linked immunoassay (ELISA) test, followed by a Western blot test.

However, it can take weeks for antibodies to develop and be detected by blood tests. Therefore, your initial test may be negative if you were recently infected. Since antibodies remain for months or even years, a blood test can not determine whether treatment is effective.

There are some ways to prevent tick bites, which include:

• Knowing where ticks live (tall grass, wooded areas, forest, gardens)
• Washing clothes in hot water after hiking or being outdoors
• Checking gear and pets
• Showering within two hours after you've been outdoors
• Checking for ticks (around the ears, behind the knees, in your hair, under your arms, etc.)
• Monitoring for any symptoms

Summary

Lyme disease is a vector-borne illness passed to humans through ticks. Lyme disease prevalence is increasing thanks to expanded tick habitats. Children ages 5 to 9 are the age group most affected by Lyme disease, followed by middle-aged people. Males are also more likely to become infected than females. Early detection is critical to avoid late Lyme disease and complications. However, most people with Lyme disease fully recover.