Lyme disease in children rising in Pennsylvania: an inside look

Lyme Disease in Children Rising in Pennsylvania: Study Data

According to the CDC, in 2016, nearly 38% of all Lyme disease cases occurred in Pennsylvania. Other studies report that ticks infected with Borrelia burgdorferi are now detectable in every county in Pennsylvania, with infection rates similar to endemic Northeastern states.

A new study examines the impact of Lyme disease among children living in western Pennsylvania over a 10-year period. The authors hoped to better understand the clinical characteristics of pediatric Lyme as they changed over the study period.

“In clinical practice, we observed an increase in the number of patients diagnosed with Lyme disease at Children’s Hospital of Pittsburgh (CHP) of the University of Pittsburgh Medical Center (UPMC), which prompted our investigation,” states Eddens and colleagues.

What the Study Found: 773 Children Over 10 Years

The authors reviewed the records of 773 children diagnosed with Lyme disease between 2003 and 2013 at Children’s Hospital of Pittsburgh, specifically assessing clinical presentation, healthcare utilization patterns, and geographic locations.

Over the 10-year period, Lyme disease cases “increased exponentially, with the highest burden of infection shifting from rural to non-rural areas.”

“An exponential increase in Lyme disease occurred in the pediatric population of western Pennsylvania,” writes Eddens from the Medical Scientist Training Program at University of Pittsburgh and Carnegie Mellon University. In fact, the actual number of pediatric cases may be much greater, as “most, but not all, children in western PA are included in our integrated EMR, so our results likely under-represent the true case numbers of pediatric Lyme disease.”

Patient Demographics and Timing

The study revealed important patterns about who gets Lyme disease and when:

• The average age of all participants was 8.1 years
• 22% of children were between 0 and 4 years of age
• 45% of children were between 5 and 9 years old
• The majority were males (59%)
• 29% had a history of a tick bite
• 62% of cases were diagnosed between May and August

Common Signs and Symptoms in Pennsylvania Children

The study documented a range of presentations:

• 56% of children had an erythema migrans rash
• 47% had joint pain
• 45% had a fever
• 31% reported joint swelling
• 30% reported headache and fatigue
• 22% had difficulty walking

Neurologic symptoms were less common, according to the study’s findings. 12% presented with cranial nerve palsy, and 11% complained of neck stiffness.

Treatment Approaches and Specialist Involvement

Most children were prescribed either doxycycline (47%) or amoxicillin (44%). Outpatient intravenous antibiotics were used to treat 15 cases of Lyme meningitis and one case of Lyme arthritis.

The children were treated by a variety of specialists. Rheumatologists identified the first 5 children. Over the years, Infectious Disease specialists, along with clinicians from Orthopedic Surgery, Neurology, and Cardiology became involved in providing care.

“In the latter years of the epidemic, as the burden of Lyme disease reached its highest in the study period, most cases were diagnosed at ED [emergency departments] and PCP [primary care pediatricians] sites,” writes Eddens.

Geographic Shift: From Rural to Non-Rural Areas

The rising numbers of children with Lyme disease was substantial. “There was an exponential increase in the number of cases of pediatric Lyme disease over the study period, with a calculated doubling time of 1.6 years,” writes Eddens and colleagues.

The number of children with Lyme disease living in non-rural areas was substantial: 503 children resided in non-rural zip codes, and 169 children were living in the city of Pittsburgh itself.

The growth in numbers of cases is not unique to western Pennsylvania. “Specifically, several areas that were once Lyme-naïve, including Ohio, Illinois, North Dakota, and Iowa, now have an increasing B. burgdorferi-infected tick population and are at-risk for expansion of Lyme disease cases, similar to how Pennsylvania was at the time of this study,” the authors explain.

Frequently Asked Questions

Why did Lyme disease in children increase exponentially in Pennsylvania?

Multiple factors contributed: expanding tick habitats in previously low-risk areas, suburban sprawl bringing children into closer contact with tick populations, and the shift of the tick-borne disease burden from rural to non-rural and urban areas. Pennsylvania saw cases double every 1.6 years over the 10-year study period.

How many children in Pennsylvania were diagnosed with Lyme disease in this study?

The study documented 773 children diagnosed with Lyme disease at Children’s Hospital of Pittsburgh between 2003 and 2013. However, researchers note this likely underrepresents the true case numbers, as not all children in western Pennsylvania were included in the hospital’s electronic medical record system.

What percentage of children with Lyme disease in Pennsylvania had the classic rash?

56% of children in this study presented with an erythema migrans rash. This means 44%—nearly half—were diagnosed without the classic rash, highlighting why clinical judgment and symptom recognition beyond the rash are essential for diagnosis.

Are children in non-rural Pennsylvania areas at risk for Lyme disease?

Yes. The study found that the burden of Lyme disease shifted from rural to non-rural areas over the 10-year period. 503 children lived in non-rural zip codes, and 169 lived in Pittsburgh itself, demonstrating that urban and suburban children face substantial risk.

Is Pennsylvania’s experience unique, or are other states seeing similar increases?

Pennsylvania’s pattern is expanding to other regions. Areas once considered Lyme-naïve—including Ohio, Illinois, North Dakota, and Iowa—now have increasing infected tick populations and are at risk for similar case expansion, according to the study authors.

Clinical Takeaway

This 10-year Pennsylvania study documents an exponential rise in pediatric Lyme disease, with cases doubling every 1.6 years and the geographic burden shifting from rural to non-rural and urban areas. Nearly half of children were diagnosed without the classic rash, and most were seen by primary care providers and emergency departments rather than specialists.

For clinicians in Pennsylvania and other expanding endemic areas: maintain high clinical suspicion even in non-rural settings, recognize that absence of a rash does not rule out Lyme disease, and consider Lyme in the differential for children presenting with joint pain, neurologic symptoms, or unexplained fatigue during tick season.