EPIDEMIOLOGICAL SURVEILLANCE
All institutions and professionals interested in forming an Epidemiological Surveillance Network are invited to create a systematic register and to promote information exchange on histoplasmosis in Latin America

Monitoring Network

All interested persons are invited to participate in the updating, concentration, and recording of histoplasmosis data in Latin America, particularly in Mexico

 

Cases Notification
Incorporation to the Network

CHARACTERISTICS OF THE DISEASE

The systemic mycosis histoplasmosis also called "histoplasmosis capsulati" can be manifested by light clinical forms, sometimes confused with an ordinary cold, to forms with severe symptoms. In Mexico, the predominating PPH clinical form is diagnosed mainly in adults and occasionally associated to lung cavitations that simulate clinical symptoms almost undistinguishable from pulmonary tuberculosis1. It is important to stress out that not all patients with the lung disease depict radiographic changes and a large number of individuals course with a subclinical form. The disseminated disease, in contrast to descriptions made in the USA, was considered a rare clinical entity, although this panorama changed as of 1980, due to the increase in the number of individuals with immunosuppression of different origins2. Immunocompromised individuals are ideal targets for fungus infections, in particular patients with AIDS. However, the anti-retrovirus therapy (HAART) boom for AIDS patients has reduced the opportunistic infections associated to AIDS, among them histoplasmosis, which frequently coursed with a severe prognosis ending in the disseminated form. Histoplasmosis is amply distributed worldwide. The endemic areas of the world with the largest number of cases are located in the valleys of the Mississippi and Ohio Rivers in the USA and in several regions of Latin America1,2.

EPIDEMIOLOGICAL SURVEILLANCE

In Mexico, it is the systemic mycosis of highest prevalence both endemically and epidemically2-5. The latter has been recorded in all federal states and represents an environmental and occupational problem, especially for those persons living or working in regions considered to be of high infection risk, where the conditions that favor H. capsulatum development prevail. However, considering its ubiquity, the endemic form might be masked due to the lack of registration. Infection risk exists for susceptible individuals in any place where suitable physical and nutritional conditions for the pathogen are found. In Mexico, the presence of the etiologic agent has been recorded in urban zones; both by its isolation from public parks and by its association to epidemics in the big cities, as was the case of a recent outbreak in Acapulco, the most important tourist center of the country, initially it was reported through a press release and short note from the CDC (Center for Disease Control and Prevention, National Center for Infections Diseases, Division of Bacterial and Mycotic Diseases) in Atlanta, USA.

It was not required to notify officially the disease until 1988, when the General Direction of Epidemiology (DGE), through the National System of Epidemiological Surveillance from the Health Ministry, included histoplasmosis in the official register of infectious diseases. From 1988 to 1994, the cases recorded by the DGE referred to the epidemic form and were found mainly in the central states of the country, followed by the South Pacific and the Gulf states2-4.

According to DGE data, histoplasmosis incidence is variable, and presents an ascending trend, starting in 1991 the morbidity rate revealed this trend in the subsequent years (see figure to the left). Since 1995, histoplasmosis cases were not anymore recorded officially; consequently, at present, the magnitude of the problem is not fully grasped, although it might be more important than officially broadcasted, taking into account what happened recently in Acapulco and that in all the American continent histoplasmosis outbreaks have been reported. Although histoplasmosis has been detected in all the national territory, it is important to emphasize that its endemic distribution varies within the same geographical area and there may be places with higher or lower infection risk4,5.

In Mexico, this mycosis should be considered more carefully by the authorities of the Health Ministry to reconsider its reincorporation to the National System of Epidemiological Surveillance. The mentioned data justify the need to increase the epidemiological studies to define endemicity criteria; to perform samplings of soil and droppings, above all in public sites at risk due to entertaining or occupational activities; to determine and update histoplasmin prevalence data, besides implementing studies on possible fungal reservoirs in nature, as part of a National Program of Epidemiological Surveillance; since, as mentioned, the infection and death indexes are of the highest in the world.

Therefore, to implement a Monitoring Network of Histoplasmosis in Mexico and Latin America would contribute to the epidemiological programs for disease control, besides its surveillance that would enable, in a near future, to establish efficient actions to reduce the infection risk for the most susceptible populations.

SPECIALIZED ATTENTION

Should the disease or risk of infection be suspected, advise, prophylactic measures, and pertinent treatment might be obtained from the following institutions in Mexico City:

REFERENCES

  1. Tewary R, Wheat LJ, Ajello L. Agents of histoplasmosis In: Medical Mycology. Topley & Wilson's, Microbiology and Microbial Infections 9thed. (eds. Ajello L, Hay RJ). New York: Arnold and Oxford University Press, 1998; pp. 373-407.
  2. Vaca-Marín MA, Martínez-Rivera MA, Flores-Estrada JJ. Histoplasmosis en México, aspectos históricos y epidemiológicos. Rev Inst Nal Enf Resp Mex 1998;11:208-15.
  3. Velasco-Castrejón O. La histoplasmosis pulmonar primaria en México. Rev Inst Nal Enf Resp Mex 1998;11:221-5.
  4. Taylor ML, Reyes-Montes MR, Chávez-Tapia CB, Curiel-Quesada E, Duarte-Escalante E, Rodríguez-Arellanes G, Peña-Sandoval GR, Valenzuela-Tovar F. Ecology and molecular epidemiology findings of Histoplasma capsulatum, in Mexico. In: Research Advances in Microbiology, (eds. Mojan RM, Benedik M). Kerala: Global Research Network, 2000; pp. 29-35.
  5. Taylor ML, Morales-Quiroz A, Chávez-Cortéz CR, García-Torres D, Montaño-Ortiz G, Pedroza-Séres M. Actualidades inmunológicas y moleculares de la histoplasmosis en Morelos, México. Gac Méd Méx 2000;136:441-7.