The Role of Fungal Infections in HIV

Infections resulting from fungi affect large numbers of individuals with HIV and AIDS and are responsible for hundreds of thousands of deaths each year worldwide. Although the number of fungal infections has fallen in the United States and other developed nations due to the ease of obtaining HIV testing and access to antiretroviral drugs (ART), the risk still exists. In less developed countries where HIV is prevalent, the need for rapid testing and treatment remains urgent.

Researchers at the Mayo Clinic College of Medicine, along with several other institutions, recently issued a paper detailing four major types of fungi that lead to infections in HIV-positive patients.

Pneumocystis jirovecii is a very common airborne fungus to which most individuals are exposed at a young age with no ill effects. However, the fungus can cause pneumocystis pneumonia in immunocompromised individuals. Roughly 400,000 cases of Pneumocystis pneumonia occur globally every year, with a mortality rate of anywhere from 10% to 30%. Those diagnosed early and without any other infections tend to fare best.

While ART has reduced the number of HIV patients who develop Pneumocystis pneumonia, the disease persists in the population of HIV-positive individuals who are not aware that they are HIV-positive, and in those who stop taking ART or for whom ART is not effective. The primary symptoms are a cough and difficulty breathing; lab tests can confirm the diagnosis. The infection can be successfully treated with drugs, but the best therapy is avoiding the infection in the first place. According to the researchers, HIV patients with low CD4 counts or history of Candida (yeast) infection in the throat should be given regular prophylactic doses of co-trimoxazole until CD4 counts rise and stay elevated for at least 3 months. In less wealthy countries, this medication regimen may also cut the risk of malaria, anemia, and poor growth in children.

The most common cause of infections of the central nervous system in HIV patients is the fungus Cryptococcus neoformans, which may lead to cryptococcal meningitis in a vulnerable HIV-infected population. Inhaled into the lungs, this fungus makes its way to the brain, causing headache, nausea, vomiting, and vision problems. Without treatment, it can lead to reduced consciousness and seizures, or even death. The fungus is known to kill 70% of sufferers within 3 months if left untreated. The problem is most acute in sub-Saharan Africa. A rapid-response test, if available, can quickly diagnose the condition. For those lucky enough to be diagnosed early, long-term antifungal therapy may allow for recovery; prophylactic treatment with the antifungal drug flucozanole may prevent HIV patients with low CD4 counts from contracting the illness in the first place.

Found in soil that contains bird or bat droppings, the fungus Histoplasma capsulatum leads to HIV-associated histoplasmosis, a disease that can affect a wide variety of organs and tissues and, if left untreated, is usually fatal. Cases of HIV-associated histoplasmosis are mainly found in Latin America as well as southeastern US states. According to the authors, histoplasmosis occurs in up to one-quarter of HIV patients.

“HIV-associated histoplasmosis is more widespread than was previously thought and is probably neglected, undiagnosed, or misdiagnosed as tuberculosis,” the authors write. Up to 60% of HIV-positive patients with histoplasmosis will die of this disease, which is characterized by fever, exhaustion, weight loss, cough, and difficulty breathing.

Finally, the fungus Talaromyces marneffei wreaks havoc on the health of HIV-infected individuals in Asia who are exposed to certain plants and animals. Talaromycosis, the resulting disease, can manifest in fever, weight loss, swelling of the liver, spleen, and lymph nodes, respiratory difficulties, and skin lesions. Roughly 10% of sufferers in Hong Kong and Thailand will die of talaromycosis; one-third of those in China and Vietnam succumb due to delayed diagnosis and relative unavailability of ART.

The report’s authors stress that antifungal medications must be made available in many more parts of the world, as must faster means of disease diagnosis. “For pneumocystis, talaromycosis, and particularly histoplasmosis, affordable, rapid point-of-care diagnostic tests, as have been developed for cryptococcosis, are urgently needed,” they write. “Such measures, together with continued international efforts for education and training in the management of fungal disease, have the potential to greatly improve patient outcomes.”

Laurie Saloman, MS, is a health writer with more than 20 years of experience working for both consumer and physician-focused publications. She is a graduate of Brandeis University and the Medill School of Journalism at Northwestern University. She lives in New Jersey with her family.