What Is Babesiosis?


Babesiosis, a parasitic infection caused by various Babesia species may sound unfamiliar, but it's a disease worth understanding. These tiny parasites are the culprits behind this ailment, and while over 100 Babesia species exist, only a handful can cause symptoms in humans. Primarily associated with livestock and pets, babesiosis also has the potential to affect humans, carried by ticks. To find out more about the causes, prevalence, and treatment of babesiosis, as well as how to protect yourself and your pets, keep reading.


There are lots of different species of Babesia, which is the parasite that causes babesiosis. Scientists have now distinguished between over 100 Babesia species, but only a few of those species can cause symptomatic infection in humans, including Babesia divergens, Babesia venatorum, and Babesia microti.1 

Babesiosis is known commonly in the agricultural industry, as it is an important animal disease best demonstrated in the infection of cattle and dogs. However, it can also infect humans, as it is a protozoan parasite carried by ticks. The parasite will be hosted within an animal, such as cattle, sheep, rodents or deer. A tick may bite this animal, pick up the parasite, and then go on to bite another new host, like another animal, or  human. However, the parasite is only then transmissible from human to human in the rare case of blood transfusion of an asymptomatic infected person to an uninfected person, or from mother to child during pregnancy.1

Prevalence and Risk Factors

Babesiosis is an extremely rare disease, and it is even rarer that an individual will experience any symptoms from infection, or fall ill after transmission of the parasite. However, in older adults and people who are immunocompromised, like people with HIV or other conditions that limit the immune response, or if you have had your spleen removed.2

Ticks are the primary vector for the parasite to move from host to host, so exposure to ticks is a significant risk factor for infections, and also means that the disease is endemic to particular regions or countries. 

Babesia parasites are primarily endemic in specific regions where suitable vectors like Ixodes ticks exist. In the United States, the Northeast, and upper Midwest, including parts of New England, New York, and Wisconsin, harbour these parasites. Certain areas in Europe, such as Austria and Germany, also experience endemicity. Regions with temperate climates, wooded or grassy landscapes, and high tick populations are more susceptible. Babesiosis cases have been reported in China, Korea, and Japan in Asia as well. Vigilance and preventive measures are essential in these endemic areas to minimize human exposure and transmission of these parasites.3

Signs and Symptoms

The majority of people infected with Babesia spp will be asymptomatic. If symptoms do show, these are usually in the form of nonspecific ailments including:

  • Headaches
  • Fever, chills, and sweats
  • Nausea
  • Fatigue
  • Body aches
  • Loss of appetite4

As infection progresses, a type of anaemia named haemolytic anaemia can develop, as the parasite infects red blood cells, causing them to die. This can lead to jaundice and darkening of the urine

If infection develops, there can be more severe complications, particularly in those individuals who are at higher risk. This can include:

  • Low blood pressure
  • Severe haemolytic anaemia
  • Severely haemolytic anaemia
  • Disseminated intravascular coagulation
  • Malfunction of the kidney, lungs, liver or other major organs
  • Death4


If you suspect you might have Babesiosis, this is the diagnosis process of this condition during its acute phase. They typically examine stained blood smears under a microscope. Additionally, xenodiagnosis or in vitro culture might be employed to isolate the parasite. For precise identification of the specific Babesia species, PCR (polymerase chain reaction) can be utilized. While serology cannot determine the exact species, it aids in epidemiological studies by assessing exposure to Babesia spp.5

Treatment and Management

In most healthy individuals, babesiosis typically goes away on its own and may not show many or any symptoms. But if someone has a weaker immune system, they might need treatment using medications like clindamycin, quinine, or other antiparasitic and antibiotic drugs. Clindamycin and quinine are the most common drugs used to treat people with serious symptoms of babesiosis.5

In some cases where clindamycin and quinine don't work, doctors might use a combination of two different drugs, atovaquone and azithromycin. For people who had their spleen removed and are dealing with severe babesiosis, blood transfusions could be part of the treatment plan.2 Remember, the right treatment should always be decided by healthcare experts. If you have any concerns, don't hesitate to talk to your doctor.


If you're going to places where there are lots of ticks that can carry Babesia parasites (like fields, woods, or marshy areas), there are some things you can do to protect yourself from getting infected. Try wearing long-sleeved shirts, pants, and hats to cover your skin. Light-colored clothes can help you spot ticks easily. You should also use tick repellents and upon coming  back from these places, make sure to check your clothes and skin, especially your scalp and the back of your neck, to make sure no ticks are on you. These steps can help you stay safe from Babesia infection.2

For pets, effective tick prevention is vital. Follow your vet’s guidance on the best protection for your dog. Opt for products that swiftly kill ticks upon attachment or repel them. Regularly check your dog for ticks, especially after walks in tick-prone areas like woodlands or places with deer and cattle. Ticks are active in warm weather but can survive year-round in sheltered spots. Therefore, consistent tick control is crucial throughout the year, not just in spring and summer.

Checking for ticks

After you've been outside, take some simple steps to avoid ticks. This is especially important in endemic areas. First, check your clothes, as ticks may cling onto them making their way into your home.. If you find any ticks, remove them. To make sure ticks are gone, put your clothes in a dryer on high heat for 10 minutes. If your clothes are damp, they might need more time. If you need to wash your clothes, use hot water because cold or medium-temperature water won't kill ticks.6

Don't forget to look at your gear and pets too. Ticks can stick to your stuff and pets, and then find their way onto you later. So, check your pets, coats, and bags carefully.

When you're back indoors, it's a good idea to take a shower within two hours. This can lower your chances of getting tick-borne diseases. Showering can help wash off any ticks that aren't attached yet. It's also a chance to do a tick check.

After being outside, it's important to check your body for ticks. Look in these spots:

  • Under your arms
  • Around your ears
  • Inside your belly button
  • Back of your knees
  • In your hair
  • Between your legs
  • Around your waist
  • Checking for ticks and taking these steps can help keep you safe from tick-related issues6


In the world of parasites, Babesia stands out as both an agricultural concern and a potential threat to humans. Though rare, this infection, transmitted through tick bites, can lead to symptoms in certain cases, especially among older adults and those with weakened immune systems. Babesia's reach is tied to the habitats of its vector, the tick, making specific regions like parts of the United States and Europe endemic to the disease. Vigilance against tick exposure, proper prevention measures, and understanding the disease's signs can help safeguard against babesiosis, ensuring that both humans and their pets remain safe.


  1. CM. Babesiosis in the uk | lyme disease action [Internet]. 2020 [cited 2023 Nov 15]. Available from: https://www.lymediseaseaction.org.uk/latest-news/babesiosis-in-the-uk/ 
  2. Babesiosis - symptoms, causes, treatment | nord [Internet]. [cited 2023 Nov 15]. Available from: https://rarediseases.org/rare-diseases/babesiosis/ 
  3. Kumar A, O’Bryan J, Krause PJ. The Global Emergence of Human Babesiosis. Pathogens 2021;10:1447. Available from: https://doi.org/10.3390/pathogens10111447.
  4. Prevention CC for DC and. Cdc - babesiosis - general information - frequently asked questions [Internet]. 2023 [cited 2023 Nov 15]. Available from: https://www.cdc.gov/parasites/babesiosis/gen_info/faqs.html
  5. Facts about babesiosis [Internet]. 2010 [cited 2023 Nov 15]. Available from: https://www.ecdc.europa.eu/en/infectious-disease-topics/z-disease-list/babesiosis/facts-about-babesiosis 
  6. CDC. Centers for Disease Control and Prevention. 2020 [cited 2023 Nov 15]. Preventing tick bites on people | CDC. Available from: https://www.cdc.gov/ticks/avoid/on_people.html 
  7. Babesiosis fact sheet [Internet]. Davies Veterinary Specialists. [cited 2023 Nov 15]. Available from: https://vetspecialists.co.uk/fact-sheets-post/babesiosis-fact-sheet/
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Olivia Laughton

BSc Microbiology (IND), University of Leeds

Having studied undergraduate Microbiology at University of Leeds, Olivia has a huge interest in all things small. Building on her academic foundation, time spent working in the health communications sector sparked passion for medical writing and education. Bridging the gap between complex science and empowering the every-day individual with health insights is where Olivia’s commitment lies, aiding the navigation to the intricacies of the science and healthcare fields alike.

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