“Ticks are the silent health threats hiding in our woods!”
Ellen Stromdahl, 2025
The mid-Atlantic region of the United States – stretching from New York to North Carolina – has long been recognized as a hotspot for tick-borne diseases. While Lyme disease has dominated headlines and public concern for decades, other illnesses associated with tick bites are on the rise.
Ellen StromdahlAmong them is Babesia microti, the parasite responsible for babesiosis, a disease similar to malaria that is transmitted by ticks. A leading researcher in this field is Ellen Stromdahl, a now-retired entomologist and tick expert who has played a significant role in identifying and analyzing the spread of tick species and the pathogens they carry, especially in the mid-Atlantic region.
Now living on the Eastern Shore of Virginia, Stromdahl was formerly associated with the Tick-Borne Disease Laboratory at the Defense Health Agency – Public Health, Aberdeen, Maryland, where she focused on vector surveillance and tick-borne disease ecology. Working at the intersection of military health, entomology, and epidemiology, she has helped advance scientific knowledge of how ticks and tick-borne diseases pose risks to both military personnel and civilians, particularly in areas where soldiers trained in forested environments.
In April of this year, Stromdahl and co-authors published an article “Emerging babesiosis in the mid-Atlantic: autochthonous human babesiosis cases and Babesia microti (Piroplasmida: Babesiidae) in Ixodes scapularis (Acari: Ixodidae) and Ixodes keiransi (Acari: Ixodidae) ticks from Delaware, Maryland, Virginia, West Virginia, and the District of Columbia, 2009 to 2024” (https://academic.oup.com/jme/article-abstract/62/4/995/8117626).
Babesiosis is a parasitic disease. The blacklegged or deer tick (Ixodes scapularis), which when infected, can transmit babesiosis, is commonly found on the Shore. These same ticks can also cause Lyme disease, anaplasmosis (manifested by potentially serious fever, headache, muscle aches, and chills) and Powassan virus, which begins with fever, headache, vomiting and weakness, and may lead to serious diseases like meningitis and encephalitis.
According to Stromdahl, Babesia affects red blood cells, much like malaria. “Babesiosis can cause serious illness, particularly in older adults, the immunocompromised, or individuals without spleens. Symptoms include fever, chills, fatigue, muscle aches, anemia and dark urine,” she said, adding that severe cases can lead to organ failure and death. Unlike Lyme disease, treatment for babesiosis requires a combination of antiparasitic drugs and quinine.
The first U.S. cases of babesiosis were confined mainly to Nantucket Island, Massachusetts, in the late 1960s, but the incidence of the disease has slowly expanded into the mid-Atlantic states, most notably the Eastern Shore of Maryland and Virginia. The mid-Atlantic’s temperate climate, deciduous forests, and growing deer populations make it an ideal environment for several tick species. The tick spreading babesiosis in this region is the blacklegged tick (commonly known as the deer tick).
The first case of locally acquired human babesiosis was reported from Queen Anne’s County, MD, in 2009. Subsequently, a team led by John Nickerson of the Queen Anne’s County Health Department, Katherine Feldman, then the Maryland State Public Health Veterinarian, and Ellen Stromdahl collected blacklegged ticks from sites around the home of the patient. Although only 16 ticks were collected, testing revealed infections with the microbes that cause babesiosis, Lyme disease and anaplasmosis.
Several factors have contributed to the expansion of ticks and tick-borne diseases. Climate change – warmer winters and longer growing seasons – allow ticks to survive and thrive in what were previously less favorable environments. Suburban sprawl, i.e., increased development of forested areas, brings people into closer contact with tick habitats. The mid-Atlantic’s abundant populations of mice and white-tailed deer are key carriers of babesia.
Compounding the issue, notes Stromdahl, is the lack of public awareness. While Lyme disease garners wide attention, many people, including medical clinicians, remain unaware of babesiosis, which leads to underdiagnosis and misdiagnosis.
“Combatting babesiosis and other tick-borne diseases in the mid-Atlantic requires a multi-pronged approach,” stated Stromdahl. “More public education, better land management techniques (especially, deer population control), personal protection (DEET or permethrin), and increased medical knowledge is necessary for increased awareness about ticks, proper tick removal techniques and symptoms of babesiosis. And healthcare providers should consider babesiosis in the differential diagnosis for patients with febrile seizures, particularly during peak tick-activity seasons.”
Stromdahl’s work has led to improved tick surveillance, personal protection strategies, and public health messaging. For Delmarva residents, the implications are critical. Outdoor recreation, hiking, gardening and even dog-walking in tick-prone environments now carries more risk. “Infections like babesiosis – especially when co-infections with Lyme or anaplasmosis occur – can be debilitating; even life-threatening,” said Stromdahl. “While we enjoy a wonderful life here on the Shore, we need to remain vigilant about the tiny neighbors inhabiting our forests.”
There are several resources available to learn more about ticks and Babesiosis:
- The Centers for Disease Control and Prevention: https://www.cdc.gov/ticks/index.html
- The Johns Hopkins Bloomberg School of Public Health: https://www.hopkinslymetracker.org/; https://publichealth.jhu.edu/lyme-and-tickborne-diseases-institute
- Tick Encounter Resource Center: https://web.uri.edu/tickencounter/
- Military Tick Identification/Infection Confirmation Kit (MilTICK) – Free tick testing for current and retired military personnel: https://ph.health.mil/topics/entomology/kits/Pages/HumanTickTestKitProgram.aspx
- The Tick App (https://tickapp.us/) on your SmartPhone
