Human Q Fever on the Guiana Shield and Brazil: Recent Findings and Remaining Questions

Purpose of Review

In this review, we report on the state of knowledge about human Q fever in Brazil and on the Guiana Shield, an Amazonian region located in northeastern South America. There is a contrast between French Guiana, where the incidence of this disease is the highest in the world, and other countries where this disease is practically non-existent.

Recent Findings

Recent findings are essentially in French Guiana where a unique strain MST17 has been identified; it is probably more virulent than those usually found with a particularly marked pulmonary tropism, a mysterious animal reservoir, a geographical distribution that raises questions.

Summary

Q fever is a bacterial zoonosis due to Coxiella burnetii that has been reported worldwide. On the Guiana Shield, a region mostly covered by Amazonian forest, which encompasses the Venezuelan State of Bolivar, Guyana, Suriname, French Guiana, and the Brazilian State of Amapá, the situation is very heterogeneous. While French Guiana is the region reporting the highest incidence of this disease in the world, with a single infecting clone (MST 117) and a unique epidemiological cycle, it has hardly ever been reported in other countries in the region. This absence of cases raises many questions and is probably due to massive under-diagnosis. Studies should estimate comprehensively the true burden of this disease in the region.

[Adrenocortical function in patients with systemic mycoses]

The systemic mycoses like paracoccidioidomycosis and histoplasmosis, are the main cause of adrenal insufficiency in the countries where they arc endemic. In Venezuela an elevated frequency of these mycoses has been registered. The objective of this study was to evaluate the glucocorticoid adrenal function in patients with paracoccidioidomycosis and histoplasmosis hospitalized in the University Hospital "Ruiz y Pácz" of Ciudad Bolivar (Bolivar state) and in the Hospital "Luis Felipe Rojas Guevara", of El Tigre (Anzoátegui state), Venezuela, between January 2003 and January 2004. The test of fast stimulation with synthetic adrenocorticotrophin hormone (ACTH) was applied to a total of 12 patients with diagnosis of some of these mycoses and data of epidemiologic interest were taken. The proportion men:women was of 5:1, the average age was 35.1 +/- 0.37 years, similar to the control group. Basal plasmatic cortisol levels were within the normal rank in all the patients. After the injection of synthetic ACTH, an increase of plasmatic cortisol values in the same rank for patients with a normal adrenal function was observed, but it was significantly lower than the observed for the control group. These results suggest that there is an adrenal gland functional reserve diminution in patients with either Paracoccidioidomycosis or Histoplasmosis. In patients with systemic mycoses, it is important to evaluate the response to the test of fast stimulation with ACTH due to the frequency of impairment of the glucocorticoid adrenal function in our location.

Epidemiological survey of histoplasmine and paracoccidioidine skin reactivity in an agricultural area in Bolívar state, Venezuela

Paracoccidiodomycosis and histoplasmosis are endemic diseases in the south of Venezuela, representing a public health problem. Prevalence of Paracoccidiodes brasiliensis and Histoplasma capsulatum infections were estimated in Monte Ralo, a rural community area of Bolivar state using paracoccidiodine and histoplasmine skin tests. Paracoccidiodine was intradermically injected to 173 persons and readings were made at 24 and 48 h afterwards to 167 persons (97.85%). Reaction was positive in 8.5% (n = 14) at 24 h post-injection and 13.2% (n = 20) at 48 h. Farmers showed the higher percentage of positivity at 24 and 48 h. One hundred-seventy five persons were intradermically injected with histoplasmine but 167 and 157 of them attended for reading of the dermal reaction at 24 and 48 h post-injection respectively. Tests were positive in 25.7% (n = 43) at 24 h and 42.7% (n = 67) at 48 h. Further studies are needed in surrounding places to delimit the endemic area of these mycosis in the Bolivar state. However, epidemiological vigilance of PCM and H should be considered by local health authorities.