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Opportunistic Fungal Infections affecting HIV/AIDS

HIV (Human Immunodeficiency virus) is a virus which attacks the body’s immune system, specifically white blood cells such as T-helper(CD4⁺) cells and macrophages . HIV positive individuals are more vulnerable to other infections and diseases, especially opportunistic infections. If left untreated, HIV can develop into AIDS (acquired immunodeficiency syndrome). This is a disease that usually occurs during the later stages of HIV and is characterized by the development of many opportunistic infections and or a CD4⁺ cell count below 200 cells per cubic millimeter of blood.

Opportunistic infections are infections from pathogens which are usually harmless to healthy individuals, but cause disease in those with weakened immune systems. Bacteria, viruses, protozoa and fungi can all cause opportunistic infection.

Cryptococcosis

Fungus: Cryptococcus

This is a fungal infection that is caused by basidiomycetous yeast cryptococcus fungi, specifically by the species Cryptococcus neoformans and occasionally Cryptococcus gattii. The cryptococcal species are morphologically encapsulated yeasts, which are commonly found in bird droppings (C. neoformans) or in higher plants (C. grattii) . They exist as teleomorphs in their sexual form and are yeast in their asexual form. These fungi are facultative intracellular organisms, which means that they are capable of reproducing and surviving both inside and outside of cells.

Usually, C. neoformans target immunosuppressed individuals, those affected by AIDS, while C. gattii frequently infects immunocompetent individuals. C. neoformans can be found worldwide, but C. gattii are usually found in subtropical regions and the Pacific Northwest. Globally, there are a reported 1 million cases of cryptococcosis and approximately 625,000 of those cases are fatal. Out of 100,000 people affected by AIDS, 2-7 have a fatal case of cryptococcosis.

Signs and Symptoms:

C. neoformans and C. gattii both cause pneumonia-like illness in the lungs while in the brain it causes meningitis. This fungus usually attacks the lungs and the central nervous system (brain and spine). Symptoms include cough, shortness of breath, chest pain, headache and confusion. C. gattii can also cause fungal growth in the lungs, skin brain and other organs. The incubation period of C. gattii is not well known but averages six to seven months after exposure to the fungus. Symptoms can take longer to develop in some people, from 13 months to up to three years, in one case,  after exposure to the fungi.

Histoplasmosis

Fungus: Histoplasma capsulatum

Histoplasma capsulatum is a dimorphic fungus, which mean that it grows in mold form at 25 degrees Celsius and in yeast form at 37 degrees Celsius. This fungus can be found in nitrogen rich soil that is contaminated with bat and/or bird droppings . It causes a pulmonary and hematogenous disease that is often chronic. It usually enters the body by spore and becomes a yeast once in the body but can be found in mold form in nature . Once it enters the body, it spreads to the lymph nodes and then circulates through the bloodstream to the rest of the body .

Signs and Symptoms:

There are three main forms of histoplasmosis:

Acute primary:

This form is a syndrome with cough, chest pain, myalgia and malaise. Acute pneumonia is evident in this form.

Chronic cavitary:

This form is characterized by pulmonary lesions which resemble cavitary tuberculosis. Coughing and dyspnea worsen in this form and eventually progresses to disabling respiratory dysfunction.

Progressive disseminated:

This form often has nonspecific or subtle symptoms such as fever, fatigue and weight loss. It is usually subacute or chronic. Several parts of the body are affected including the central nervous system, which leads to meningitis or focal brain lesions. Adrenal infection and pneumonia are rare but are possible in this form

Pneumocystis pneumonia (PCP)

Fungus: Pneumocystis jirovecii

Pneumocystis jirovecii, previously known as Pneumocystis carinii, is a yeast-like fungus in the genus Pneumocystis. It attacks the lung and causes pneumonia in individuals with weak immune systems. Since healthy adults can carry the fungus in their lungs, the fungus can spread from person to person through these asymptomatic carriers.

Similar to the other fungi above, PCP is rare in healthy people. However, 40% of people who have PCP also have HIV/AIDS and the other 60% are immunosuppressed. About 20% of adults might carry this disease at any time with no symptom. The body can usually eradicate the illness in a few months . However, PCP can be fatal if not treated.

Signs and Symptoms:

PCP symptoms usually develop over a few days. Symptoms include chest pain, chills and difficulty breathing.

Treatment

HIV is treated with antiretroviral therapy, or ART. These are medications that, when taken in combination, help to mitigate the effects of HIV and slow the onset of AIDS. If CD4+ cell count is kept above 200 cells/ mm3, then opportunistic infections will not be as chronic, and your body would have a better chance of fighting off these fungi. C. neoformans infections are treated with antifungal medication. Those with asymptomatic or mild-moderate pulmonary infections are given fluconazole. For more severe infections or meningitis, a combination of amphotericin B and flucytosine are used first, followed by fluconazole to clear the infection. Duration and type of treatment depends on the patient’s physical state.  Fungal growths (cryptococcomas) is surgically removed . Disseminated forms of histoplasmosis or cases which affect the lungs can be treated with antifungal medication such as Itraconazole. The treatment can range from 3 months to 1 year, depending on the severity of the infection . PCP can be treated with prescription medicine and the most common form of treatment is trimethoprim/sulfamethoxazole (TMP/SMX). This can be given orally or through IV. The side effects of TMP/SMX rash and fever .