Histoplasmosis common and severe even after HAART became available in Panama

Histoplasmosis has remained a common and severe infection in HIV-positive patients in Panama, even after the introduction of HAART, according to an article to be published in the April 15^th edition of Clinical Infectious Diseases (now available on-line). The investigators found that patients presenting with histoplasmosis often had another opportunistic infection, undiagnosed HIV infection and severe immune suppression.

Histoplasmosis is caused by the fungi Histoplasma capsulatum, and although rare in the UK, it is common in Central and Southern America. Although environmental conditions in Panama are favourable to histoplasmosis, the condition was rare in the country until the advent of HIV. It is estimated that 1.5% of the population in Panama have an AIDS diagnosis, and disseminated histoplasmosis is a common reason for admission to the HIV ward at the Arnulfo Arias Madrid hospital in Panama City, and is often the first condition indicative of severe immune suppression diagnosed in HIV patients.

Investigators at the Arnulfo Arias Madrid Hospital wished to determine the incidence, clinical characteristics, method of diagnosis, and outcome of disseminated histoplasmosis amongst patients admitted to their ward between 1997 and 2003. HAART was made available to patients in Panama in 1999. A retrospective review of medical records was conducted.

A total of 2379 patients were admitted to the AIDS ward between 1997 and 2003 and 182 patients (8%) had confirmed disseminated histoplasmosis. However, the investigators restricted their analysis to the 104 patients whose medical records were available.

Fever was the most common symptom, present in 92% of patients, but respiratory symptoms (64%), weight loss (62%) and diarrhoea (50%) were also common. Chest X-rays were performed on 54 patients, and were abnormal for 44 individuals.

A diagnosis of histoplasmosis was confirmed on the basis of a blood culture in over two-thirds of patients (67%), and over half of patients (51%) also had a bone marrow culture confirming the infection.

Another opportunistic infection was present in over a quarter of patients (27%), tuberculosis being the most common and diagnosed in 16 individuals. At the time when histoplasmosis was diagnosed, only 11 patients were taking HAART.

The median age of patients was 37 years, 88 were men, and 57% had heterosexual sex as their HIV risk factor, sex between men accounting for 28% of cases.

Severe immune suppression was present in the majority of patients, with 73 individuals (80%) having a CD4 cell count below 100 cells/mm³. The median CD4 cell count for all patients at the time of histoplasmosis diagnosis was only 65 cells/mm³.

Treatment with amphotericin B deoxycholate was provided to nearly all the patients (100 individuals, 96%), although three patients died before they were provided with antifungal therapy. In total, 40 patients experienced side-effects to this treatment, the most common being hypocalaemia (20 individuals) and increased creatitine levels (17 patients).

In total 13 patients (12%) died, the majority within 30 days of admission to hospital.

Commenting on their findings, the investigators note that there has not been a decline in the incidence of histoplasmosis amongst HIV-positive individuals since Panama made HAART available in 1999. They believe that this is “because it is often the first manifestation of the disease [HIV]. This pattern reflects that of the AIDS epidemic in Panama: HIV-infected people seek medical attention during the advanced stages of the disease when they have one or more life-threatening opportunistic infections to fight before HAART can be effective.”