ABSTRACT
Toxoplasmosis, a typical cosmopolitan parasitosis, is a major health problem in French Guiana. Three factors account for this situation, i.e., (1) severity of toxoplasmosis in patients with HIV infection that is particularly prevalent in the area, (2) high risk of congenital transmission as shown by the steadily increasing prevalence of seropositivity in function of age in most of the Guianese population and (3) recent identification of severe primary toxoplasmosis infection in immunocompetent patients. In AIDS patients, the epidemiologic aspects of toxoplasmosis are correlated to the special features of the HIV-positive population in French Guiana and its clinical expression, mainly in the form of cerebral toxoplasmosis, does not suggest involvement of a particularly virulent strain of Toxoplasma. Similarly congenital toxoplasmosis does not present special tropical features other than problems associated with prevention, diagnosis and follow-up in poor and/or remote settings. These features are fully compatible with the classic domestic cat cycle of Toxoplasma gondii. However severe forms of primary infection, particularly in immunocompetent adults, appear to be associated with atypical features. These forms appear to be correlated with a forest-based cycle involving wild cats, which are still numerous in French Guiana, and their prey. Ingestion of undercooked wildcat prey, which is also a delicacy for man, can also be a source of contamination as can be consumption of untreated river water infected with oocysts excreted by felines. Observation of higher toxoplasmosis seroprevalence in wild noncarnivorous mammals that live by foraging on the ground in uninhabited forest zones suggests that infection can also be due to ingestion of oocysts eliminated into the soil. Since there are no domestic cats in the area, it must be assumed that these oocysts are shed by wild felines. More convincing proof can be seen in the fact that T. gondi strains presenting polymorphism, similarities and atypical genetic features can be found both in this animal reservoir, particularly in jaguars, and in patients presenting the more severe form of toxoplasmosis. In addition to the purely scientific interest of confirming the existence of the forest-based cycle, knowledge of this atypical form of toxoplasmosis that is probably not confined to French Guiana or to the Amazon region has obvious practical medical implications not only for diagnosis but also for therapy and prevention.
