Carme B, Demar-Pierre M
Laboratoire Hospitalo-Universitaire de Parasitologie et Mycologie Médicale, Centre Hospitalier de Cayenne et Faculté de Medecine des Antilles et de la Guyane.
Med Trop (Mars). 2006 Oct;66(5):495-503.
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.
弓形虫病是一种典型的世界性寄生虫病，在法属圭亚那是一个主要的健康问题。造成这种情况的有三个因素，即：（1）HIV感染患者中弓形虫病的严重程度，该疾病在该地区尤为普遍；（2）先天性传播的高风险，正如大多数圭亚那人群中血清阳性率随年龄稳步上升所显示的那样；（3）最近在免疫功能正常的患者中发现了严重的原发性弓形虫感染。在艾滋病患者中，弓形虫病的流行病学方面与法属圭亚那HIV阳性人群的特殊特征相关，其临床表现主要为脑弓形虫病，这并不表明存在特别毒力的弓形虫菌株。同样，先天性弓形虫病除了在贫困和/或偏远地区与预防、诊断及随访相关的问题外，没有呈现出特殊的热带特征。这些特征与刚地弓形虫经典的家猫传播循环完全相符。然而，原发性感染的严重形式，特别是在免疫功能正常的成年人中，似乎与非典型特征有关。这些形式似乎与涉及野猫的森林传播循环有关，野猫在法属圭亚那仍然很多，还有它们的猎物。食用未煮熟的野猫猎物（这也是人类的一道美味）以及饮用被猫排出的卵囊污染的未处理河水都可能是感染源。在无人居住的森林地区以地面觅食为生的野生非食肉哺乳动物中观察到较高的弓形虫血清阳性率，这表明感染也可能是由于摄入了排入土壤中的卵囊。由于该地区没有家猫，必须假定这些卵囊是由野生猫科动物排出的。更有说服力的证据是，在这个动物宿主中，特别是在美洲虎中，以及在呈现更严重弓形虫病形式的患者中，都能发现具有多态性、相似性和非典型遗传特征的刚地弓形虫菌株。除了确认森林传播循环存在的纯粹科学意义外，了解这种可能不限于法属圭亚那或亚马逊地区的非典型弓形虫病形式，不仅对诊断，而且对治疗和预防都具有明显的实际医学意义。
