HISTOPLASMOSIS IN THE AMERICAS: THE ROUTE TO AWARENESS

Histoplasmosis is a systemic mycoses that is often misdiagnosed and mistaken for tuberculosis. In a recent commentary in the Journal of fungi, Nacher et al have described how specialists in 4 countries became fully aware of the threat posed by histoplasmosis to immunocompromised HIV patients. The countries are French Guiana, Brazil, Guatamela and Colombia. These countries are now known to be hotbeds of histoplasmosis and disseminated disease is recognised as an AIDS defining condition.

This was not always so.

In French Guiana, it took  the dermatologists’ proactive search for pathogens in skin lesions to shed light on the problem.

In  Fortaleza, Brazil, the first cases of disseminated histoplasmosis (DH) were “accidentally” diagnosed when buffy coat was used to look for Leishmania in the peripheral blood of patients with presentations compatible with Kala-azar. A microbiologist (Jacó Ricarte L. Mesquita) working at the laboratory of São José Hospital, increasingly saw images of yeasts inside leukocytes in peripheral blood smears of febrile AIDS patients. He sent these samples for fungal culture at a reference laboratory at the Federal University of Ceará, which identified the presence of Histoplasma. The adoption of diagnostic methods such as microscopy and culture of buffy coat and later screening with lactate dehydrogenase were useful in reducing mortality due to histoplasmosis.

The experience in Guatamela could be summed up as ‘the more you look for histoplasmosis, the more you find it’.

In Africa, histoplasmosis is still very much a neglected disease. However, some countries are well on their way to awareness. Several studies have sprung up from Cameroon and South Africa documenting disseminated histoplasmosis in HIV patients. In Nigeria, the first histoplasmin skin sensitivity test survey in over thirty years was conducted in 2017: the results showed a prevalence of 4.4%. There is work to be done as we begin this journey to uncover the toll on the advanced HIV disease populace. The more we look, the more we will find.