What is the relationship between toxoplasmosis and HIV?

Toxoplasma Gondii
Toxoplasma Gondii. BSIP/UIG/Getty Images

What is Toxoplasmosis?

Until the 2015 controversy where a drug executive raised the price of a drug for toxoplasmosis more than 5000 percent, most people had probably never heard of the condition. A lot of journalists talked about the drug as being an HIV drug, but that's not strictly true. Toxoplasmosis is a parasitic infection. In most people, the immune system can fight it off easily. However, immunocompromised people, such as those who are HIV positive, can develop serious problems if infected.

Complications of toxoplasmosis can include blindness, seizures, and even encephalitis.

Does Toxoplasmosis Only Infect People with HIV?

Pregnant women are also often warned about possible exposure to the parasites that cause toxoplasmosis. It can infect the fetus or infant, potentially leading to blindness, hearing loss, or mental disabilities. In fact, toxoplasmosis is why pregnant women are often counseled not to change cat litter. Cats can carry the parasite. However, it's only dangerous for infants if their mothers become infected during pregnancy. Women who were infected before they became pregnant are unlikely to transmit the infection.

How Do People Get Toxoplasmosis?

People most often become infected with toxoplasmosis when they ingest either tissue cysts containing parasitic eggs or spores containing those same eggs. This can happen from eating infected meat. It can also be due to poor hygiene or hand washing practices.

Toxoplasmosis is not only found in cat feces. It's also found in many other organisms and their feces, and the spores can contaminate soil and water. That's one of the reasons people recommend wearing gardening gloves when working in the dirt!

Thoroughly cooking meat products reduces the risk of infection with toxoplasmosis, as well as other parasites.

So does good hygiene. Washing hands before eating is important. So is thoroughly cleaning hands after changing cat litter and engaging in other activities with the potential of exposure to toxoplama. In addition, its important to clean fruits and vegetables well, since they may have surface contamination by the parasite.

How Common is Toxoplasmosis in People with HIV?

Toxoplasmosis is incredibly common. Studies estimate that around 25-30 percent of the general population show evidence of infection with the Toxoplasma gondii parasite. However, most of those infections don't cause problems. What causes problems, most often, is when the parasite  reactivates in the central nervous system and/or the brain. This is more likely to happen in people with compromised immune systems, such as those with advanced HIV. (When HIV is properly treated, the immune system is not any more susceptible than for uninfected people. It is people with a CD4 count of <100 who are most vulnerable. Those people have AIDS. They are considered to be severely immunocompromised

Toxoplasmosis is one of the most common opportunistic infections affecting the central nervous system in individuals with advanced HIV/AIDS.

As with other opportunistic infections, it has become less common as more effective HIV treatments have become available. Because of these treatments, more people are able to keep infection under control. Long term adherence to combined antiretroviral therapies (cART) help keep the immune systems of individuals with HIV healthier. With such treatment, the immune systems of HIV+ people stay basically as functional so those of people who are HIV-. This makes opportunistic infections, such as a reactivation of toxoplasmosis, less likely to occur.


Opsteegh M, Kortbeek TM, Havelaar AH, van der Giessen JW. Intervention strategies to reduce human Toxoplasma gondii disease burden. Clin Infect Dis. 2015 Jan 1;60(1):101-7. doi: 10.1093/cid/ciu721. Epub 2014 Sep 15.

Pollack, A (2015, September 20) "Drug Goes From $13.50 a Tablet to $750, Overnight". New York Times. Accessed 12/19/15 from http://www.nytimes.com/2015/09/21/business/a-huge-overnight-increase-in-a-drugs-price-raises-protests.html?_r=0

Robert-Gangneux F, Dardé ML. Epidemiology of and diagnostic strategies for toxoplasmosis. Clin Microbiol Rev. 2012 Apr;25(2):264-96. doi: 10.1128/CMR.05013-11.

Yan J, Huang B, Liu G, Wu B, Huang S, Zheng H, Shen J, Lun ZR, Wang Y, Lu F. Meta-analysis of prevention and treatment of toxoplasmic encephalitis in HIV-infected patients. Acta Trop. 2013 Sep;127(3):236-44. doi: 10.1016/j.actatropica.2013.05.006.

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