Babesiosis (Piroplasmosis) in Cats

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Key takeaways

Babesiosis in cats is a serious tick-borne disease resulting from infection with the Babesia parasite. 

  • Transmission of Babesia involves a bite from an infected tick of the Ixodes tick family
  • Ixodes ticks are found worldwide, but species carrying feline babesiosis are active primarily in southern Asia and sub-saharan Africa
  • Babesia infects the blood cells, resulting in blood cell destruction and anemia
  • Cats with babesiosis present primarily with lethargy, poor appetite, weight loss, weakness, and pale gums
  • Investigation involves physical examination and blood work
  • Definitive diagnosis involves detection of Babesia through microscopic examination of the blood or specialized testing
  • Treatment options include antiparasitic medication alongside symptomatic treatment of anemia such as fluid therapy and blood transfusions
  • Prognosis varies depending on severity of the anemia and response to treatment
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A closer look: Babesiosis (Piroplasmosis) in Cats

Babesiosis is primarily a tick-borne infection and is normally restricted to animals living in, or traveling to, areas where the ticks are endemic.

Babesia species that infect cats are more resistant to antiparasitic medication than canine species, making treatment less effective in some cats.

Cats suspected of babesiosis require urgent veterinary attention.

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Risk factors

Symptoms vary significantly in cats, as they are often able to adapt to mild or moderate anemia.

Other cases show no symptoms. Some severely affected cats present with acute collapse and sudden death.

Babesiosis is less common in cats than in dogs, and no cases have been reported in North America. Ticks carrying feline Babesia species are most prevalent in southern Asia and sub-saharan Africa.

Cats usually adapt to mild to moderate anemia, and may show no symptoms and clear infection without treatment. Cases of severe anemia are sometimes fatal.

Possible causes

The Ixodes tick species become infected with Babesia after feeding on an infected animal. If an infected tick bites and feeds on a cat, it can pass the parasite on.

Once a cat becomes infected with Babesia, the parasite infects the red blood cells, causing the immune system to identify and destroy the infected cells. The destruction of red blood cells ultimately results in anemia.

Transfer of infected blood between cats sometimes results in infection. Alternative infection routes include:

  • Cat fights
  • Transfer from mother to kittens in the uterus
  • Blood transfusions

Main symptoms

Testing and diagnosis

Investigation of babesiosis involves:

  • Physical examination
  • Blood work
  • Microscopic detection of Babesia inside the blood cells
  • Identification of antibodies against the parasite in the bloodstream
  • Identification of parasitic proteins in the bloodstream

Steps to Recovery

The goals of treatment depend on the severity of the infection and symptoms. In some cases, simply resolving symptoms is the goal of treatment, while in others, complete resolution of infection is desired. Treatment options include:

  • Antiparasitic medication
  • Immunosuppressive medications in some cases
  • Fluid therapy
  • Blood transfusions

Prognosis varies depending on the severity of anemia at presentation, the particular species of Babesia infection present, and the overall health of the cat at the time of infection.

Most patients show signs of improvement within 1-2 weeks of treatment. Repeated blood work is required to monitor anemia and ensure that treatment is successful. Some species of Babesia in cats are resistant to antiparasitic medication, and may not respond to treatment or relapse several weeks later. Some cats cannot clear the infection completely even with treatment, and become lifelong carriers of the parasite.

Cats with severe anemia have a poorer prognosis. Most cats with babesiosis recover, but it is fatal in 1 in 5 cases.


Babesiosis is a vector-borne disease, and prevention involves tick control. Effective tick control requires year-round use of veterinary-approved antiparasitic preparations effective at preventing attachment and feeding of ticks.

Note: always consult a veterinarian before choosing external parasite control for cats. Many products on the market are not effective or safe. Some products are highly toxic to cats.

Prevention of blood transfer as a source of infection is only necessary in endemic areas, but includes:

  • Careful screening of blood donor cats for Babesia
  • Ensuring stray cats don’t enter the property
  • Not breeding from cats with babesiosis

Is Babesiosis (Piroplasmosis) in Cats common?

Prevalence depends on the geographical location of the ticks that transmit Babesia. Feline babesiosis is more common in southern Asia, and sub-saharan Africa. No cases have been reported in North America.

Typical Treatment

  • Anti-parasitic medication
  • Fluid therapy
  • Blood transfusions


Michael Kearley, DVM - Writing for PetMD
Phillip D. Carter , BVSc, MVS / Peter Rolls , BVSc, MVS - Writing for Merck Veterinary Manual
No Author - Writing for Companion Animal Parasite Council
No Author - Writing for Wag!

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