Babesiosis

Clear→ stable

Vector-borne

Current NYS Status

748 cases in 2024 — near the 5-year baseline of ~1,095.

2024 statewide cases: 748

Source: NYSDOH Annual Communicable Disease Report 2024 + 5-yr baseline

What is it?

Babesiosis is caused by Babesia microti, a microscopic parasite that infects red blood cells, transmitted by blacklegged ticks. NYS had 748 cases in 2024, concentrated in Suffolk County and the eastern end of Long Island. Severe cases involve hemolytic anemia requiring hospitalization.

How it spreads

Transmitted primarily by the bite of infected blacklegged ticks. Can also be transmitted through blood transfusion — babesiosis is the most common transfusion-transmitted parasitic infection in the US. Peak season is June through August.

Symptoms

Ranges from asymptomatic to severe. When symptomatic: fever, chills, sweats, fatigue, headache, and body aches similar to malaria. Severe disease involves hemolytic anemia (breakdown of red blood cells), low platelet count, and can progress to organ failure.

Who is at risk?

Adults over 50, people without a spleen, and immunocompromised individuals are at high risk for severe and potentially life-threatening disease. People on Long Island face the highest regional risk.

What you can do

🛡Use tick repellent and check thoroughly for ticks after outdoor activities, especially on Long Island

🛡Remove attached ticks promptly

⚕️Seek medical care urgently for fever and flu-like symptoms after tick exposure if you are immunocompromised or asplenic

👁If you have had babesiosis, inform healthcare providers and blood banks before any blood donation

Tier B — Annual report tracking

Based on NYSDOH annual communicable disease report. Threat level reflects 2024 case counts compared to the 5-year baseline.

Seasonality: tick season

This information is for general public health awareness and is not a substitute for professional medical advice, diagnosis, or treatment.