Tick-Borne Illnesses: Protecting Humans and Pets in a Growing Public Health Challengereatment, Care, and Prevention

Tick-borne diseases are rising sharply across North America, driven by climate change, expanding tick ranges, habitat fragmentation, and increased outdoor activity by both people and pets. These illnesses affect humans and companion animals through the same vectors, making a One Health approach essential. Dogs and cats often serve as sentinels—detecting infected ticks in an environment before humans show symptoms. Understanding the shared risks, differences in disease expression, and coordinated prevention strategies helps protect entire households.

This updated overview draws on the latest data from the CDC, Companion Animal Parasite Council (CAPC) 2025–2026 forecasts, AVMA, peer-reviewed veterinary literature, and clinical guidelines to cover burden, impacts, treatment, care, and prevention for both people and pets.

Expanding Risks for People and Pets

Blacklegged ticks (Ixodes scapularis and I. pacificus), lone star ticks (Amblyomma americanum), American dog ticks (Dermacentor variabilis), and brown dog ticks (Rhipicephalus sanguineus) transmit the majority of pathogens. CAPC’s 2026 Pet Parasite Forecast projects continued geographic expansion of Lyme disease, anaplasmosis, ehrlichiosis, and related infections into previously lower-risk areas, including parts of the Midwest, Ohio Valley, Southeast, and westward. Similar patterns appear in human surveillance.

Key shared pathogens include:

• Borrelia burgdorferi (Lyme disease) — primarily blacklegged ticks
• Anaplasma phagocytophilum and A. platys (anaplasmosis)
• Ehrlichia canis, E. ewingii, and E. chaffeensis (ehrlichiosis)
• Babesia species (babesiosis)
• Rickettsia rickettsii (Rocky Mountain spotted fever / RMSF)
• Powassan virus (primarily humans; rare severe disease)

Cats face additional risks such as cytauxzoonosis (“bobcat fever”) from Cytauxzoon felis, transmitted mainly by lone star ticks. Alpha-gal syndrome (red meat allergy) affects humans after certain tick bites but does not occur clinically in dogs or cats, as they naturally produce the alpha-gal sugar molecule.

Dogs show higher seroprevalence than cats for most agents. Recent feline testing (2022–2025) found exposure rates roughly 14–28% of those reported in dogs for the same pathogens. Coinfections are common in both species and can worsen outcomes.

Clinical Impacts: Humans vs. Pets

In humans, early symptoms often include fever, headache, fatigue, muscle aches, and (for Lyme) the characteristic erythema migrans rash. Untreated infections can progress to neurologic, cardiac, joint, or multi-organ involvement. RMSF and severe anaplasmosis/ehrlichiosis can be life-threatening if treatment is delayed. Powassan virus carries a significant risk of encephalitis and long-term neurologic deficits. Alpha-gal syndrome causes delayed allergic reactions (hives to anaphylaxis) after eating mammalian meat or dairy.

In dogs, signs frequently include fever, lethargy, loss of appetite, shifting-leg lameness or joint pain (classic for Lyme), swollen lymph nodes, and thrombocytopenia (low platelets leading to bruising or bleeding). Lyme can progress to serious kidney disease (Lyme nephritis), especially in certain breeds. Ehrlichiosis may become chronic with bone-marrow suppression. Babesiosis causes hemolytic anemia. Many dogs show mild or no clinical signs despite infection, which is why annual screening is valuable.

In cats, clinical disease is less common overall, but when it occurs it can be severe. Cytauxzoonosis is often rapidly fatal without aggressive treatment. Anaplasmosis and ehrlichiosis may cause fever, lethargy, and blood abnormalities. Cats can carry ticks into the home even if they rarely show illness themselves.

Pets and people share the same outdoor environments, so a positive tick-borne disease test in a dog often signals elevated risk for the household. For a broader checklist of symptoms that warrant attention, see our pet health warning signs guide.

Diagnosis

For humans, diagnosis relies on clinical signs plus two-tier serology (or modified testing), PCR when appropriate, and blood-smear examination for certain pathogens (e.g., Babesia, morulae in anaplasmosis/ehrlichiosis). Early Lyme with classic rash is often treated without waiting for labs.

For pets, veterinarians commonly use point-of-care SNAP 4Dx or similar tests that screen for antibodies to Borrelia, Anaplasma, Ehrlichia, and heartworm antigen. Positive results may prompt PCR confirmation, complete blood counts, chemistry panels, or urine testing (especially important for Lyme nephritis monitoring). Annual screening is recommended in endemic or expanding-risk areas.

Treatment and Care

Bacterial infections (Lyme, anaplasmosis, ehrlichiosis, RMSF)
Doxycycline is the first-line treatment for both humans and dogs (and generally cats when indicated).

• Humans: Duration varies by disease and severity (often 10–14 days for early Lyme or anaplasmosis; longer for disseminated disease or RMSF).
• Dogs: Typically 28 days for Lyme, ehrlichiosis, or anaplasmosis (10 mg/kg once daily or divided). Clinical improvement is often rapid (24–48 hours). Supportive care (fluids, anti-inflammatories, or transfusions for severe anemia/thrombocytopenia) is added as needed.
  Cats receive adjusted dosing and careful monitoring.

Babesiosis
Humans and dogs require antiprotozoal therapy (atovaquone + azithromycin is common; imidocarb is used for certain canine Babesia species). Severe cases may need blood transfusions or hospitalization.

Viral infections (e.g., Powassan)
Supportive care only; no specific antivirals.

Cytauxzoonosis in cats
Aggressive antiprotozoal therapy plus intensive supportive care; early intervention is critical.

Prompt treatment dramatically improves outcomes in both species. Incomplete or delayed therapy raises the risk of chronic or severe complications.

Prevention: Shared Strategies That Protect Everyone

Prevention is far more effective and less costly than treatment. Because the same ticks affect people and pets, coordinated measures work best.

For pets (year-round is essential)

• Use veterinarian-recommended isoxazoline products (oral or topical: e.g., afoxolaner, sarolaner, fluralaner, lotilaner) or other proven acaricides. CAPC and AVMA emphasize continuous, year-round protection due to expanding tick activity.
• Lyme disease vaccines are available and recommended for at-risk dogs (especially in endemic or expanding regions).
• Perform thorough tick checks after outdoor activity and remove any attached ticks promptly with fine-tipped tweezers.
• Keep yards tidy: mow regularly, reduce leaf litter and brush, and create barriers between lawns and wooded areas.

For seasonal risks beyond ticks, read our summer pet health guide. Our at-home dog grooming guide helps make routine coat checks part of your care habits. The 7-piece dog grooming kit can help with ordinary grooming, but is not a tick repellent or a substitute for veterinarian-recommended parasite prevention.

For humans

• Apply EPA-registered repellents (DEET, picaridin, IR3535, oil of lemon eucalyptus) and treat clothing with permethrin.
• Wear protective clothing, stay on trails, and perform full-body tick checks after being outdoors.
• Shower soon after potential exposure.
• Consider emerging human Lyme vaccine candidates once available (phase 3 data as of 2026 showed promising efficacy for one leading candidate).

Household-level actions
Treating pets reduces the number of ticks brought into the home, lowering risk for people. Environmental measures that reduce tick habitat benefit everyone. Pets cannot transmit most tick-borne pathogens directly to humans through casual contact; transmission still requires a tick bite.

Looking Ahead

CAPC forecasts and CDC surveillance confirm that tick ranges and pathogen prevalence will continue expanding. Integrated One Health strategies—combining pet preventives, human personal protection, environmental management, and improved diagnostics—offer the best defense. Regular veterinary visits that include parasite screening, coupled with awareness of human symptoms, create an early-warning system for the entire family.

If your pet tests positive for a tick-borne pathogen or shows unexplained fever, lethargy, or lameness, contact your veterinarian promptly and consider personal protective measures or medical evaluation for household members who share the same outdoor spaces. For the most current local risk maps and product recommendations, consult the CDC (cdc.gov/ticks), CAPC (capcvet.org), and your veterinarian or physician.

Key References

• Companion Animal Parasite Council (CAPC) 2025 & 2026 Pet Parasite Forecasts.
• CDC Tickborne Disease resources and surveillance data (through 2026).
• AVMA reports and JAVMA reviews on One Health tick management (2026).
• Clinical guidelines: IDSA/AAN/ACR 2020 Lyme guidelines (humans); ACVIM consensus and CAPC guidelines (dogs/cats).
• Recent seroprevalence studies in dogs and cats (2022–2025) and peer-reviewed literature in Journal of Veterinary Internal Medicine, Veterinary Parasitology, and Emerging Infectious Diseases.

Protecting pets and people from ticks is a shared responsibility—and one of the most effective ways to reduce the growing burden of these preventable diseases.