until 1998 , only 2 cases of severe primary toxoplasmosis had been reported in french guiana , in 1992 ( 1 ) and 1997 ( 2 ) . however , from 1998 through 2006 , 44 cases occurred ( 35 ) . all patients were immunocompetent ( not hiv - infected ) adults who had been hospitalized because of a marked , nonspecific , infectious syndrome . all patients had elevated and prolonged fever ; most had weight loss , hepatic cytolysis , lymphadenopathy , headache , and pneumopathy . other signs such as rash , retinochoroiditis , myocarditis , myositis , and neurologic disorders , may occur with toxoplasmosis , albeit infrequently . prognosis is linked to lung involvement , which typically occurs 1015 days after onset of fever and requires hospitalization . approximately one third of patients with this severe form of disease experience respiratory distress and need to be in an intensive care unit . unless specific treatment ( sulfadiazine and pyrimethamine ) is initiated quickly acute toxoplasmosis was diagnosed by serologic tests , which suggested recent primary infection ( substantial and rapid increase in immunoglobulin [ ig ] g , associated with specific igm , in 2 separate samples taken 12 weeks apart tested at the same time ) ; by blood or bronchoalveolar lavage samples positive by pcr ; and by absence of an alternative cause . microsatellite analysis performed on isolated strains or on toxoplasma dna extracts showed that all isolates exhibited an atypical multilocus genotype , in contrast with strains usually described in europe or north america . most patients reported forest - related activities such as ingestion of surface water , consumption of undercooked game meat , and hunting . we recently described an outbreak of toxoplasmosis from late december 2003 through mid january 2004 involving 11 cases among the 38 inhabitants of a village in suriname near the french guiana border ( 6 ) . using 8 microsatellite markers with a high power of discrimination , we described a unique multilocus genotype for 5 patients and demonstrated that only 1 strain was responsible for this outbreak ( in at least 5 of 11 patients ) . however , the same strain was responsible for different clinical outcomes in each of the 11 patients : 2 cases were congenital and lethal , 9 cases occurred in immunocompetent adults ( 5 patients , 1 of whom died , had disseminated toxoplasmosis and needed hospitalization ; and 4 had less severe disease with no life - threatening signs or need for hospitalization ) . genetic susceptibility of the host to this unusually severe form of toxoplasmosis may explain in part the severity of symptoms , although we observed this disease in the different ethnic groups of french guiana ( caucasians from inland france , creoles , amerindians , bushineng , and brazilians ) . such a severe outcome in humans may be explained by poor host adaptation to emerging and highly virulent strains of t. gondii circulating in a forest - based cycle involving wild felids ( definitive hosts ) and their prey ( intermediate hosts ) ( figure ) . the high seroprevalence for noncarnivorous wild mammals in french guiana , especially terrestrial animals such as deer , armadillos , pacas , and peccaries ( 7 ) , suggests oral exposure to oocysts eliminated by wild felids in the absence of domestic cats ( 8) . wild felids are still numerous in french guiana . isolation of 1 genetically atypical toxoplasma strain in a free - living jaguar ( panthera onca ) is a further argument for the existence of a t. gondii wildlife cycle ( 9 ) . sources of contamination are uncooked meat from hunted game and river water containing oocysts excreted by wild cats . transmission cycle of highly virulent strains of toxoplasma gondii involving wild felids ( definitive hosts ) and their prey ( intermediate hosts ) . in north america and in western europe , t. gondii has been considered to have a clonal population structure and low genetic diversity ; > 95% of strains belonged to 3 clonal lineages , types i , ii ( mainly ) , and iii ( 10 ) . the greater genetic diversity of t. gondii in a wild and tropical environment , compared with the domestic environment , could be connected to the considerably higher diversity of hosts in the wild . in the neotropical rain forest , fauna are abundant and highly diverse ; 560 species of mammals have been recorded ( 11 ) . a plurality of alleles is needed for t. gondii to colonize a maximum of ecological niches in such a diverse environment . because little molecular assessment has been performed for t. gondii from asymptomatic infected persons in french guiana , it is difficult to know what proportion of persons infected with the atypical strains found there have severe disease . in french guiana , a wild cycle of t. gondii coexists with a domestic cycle , in which cats take a central role . both cycles , wild and domestic for the domestic cycle , there are 11 dna samples ( 6 urban isolates from animals raised in captivity [ 3 cats and 3 monkeys ] and 5 human isolates from patients with classical disease [ 2 aids patients with cerebral toxoplasmosis , 2 patients with congenital infections , and 1 patient with lymphadenopathy ] ) . recent studies that used multiple markers and collected samples from other countries have shown that , at least in the tropical part of south america , t. gondii strains have higher genetic diversity ( 12,13 ) . few data concerning the genetic diversity and population structure of this parasite are available in africa ( 14 ) and asia ( 15 ) . the number of cases of this severe form of primary t. gondii infection ( > 50 well - documented observations in the past decade ) is particularly high in french guiana , given the small size of the population ( 200,000 inhabitants ) , compared with the low number of published cases . although such a wild t. gondii cycle with severe human clinical consequences has not been described in brazil or in other countries of the guyana shield , it seems unlikely that it is a disease specific to french guiana . amazonian areas , and likely other rain forest areas where felids live , could be affected by this form of toxoplasmosis , which could be designated  amazonian toxoplasmosis  or  wild rain forest toxoplasmosis .  from a healthcare perspective worldwide , physicians should consider a diagnosis of acute toxoplasmosis as soon as possible after the onset of signs and symptoms in patients who live in or have recently visited the amazonian region and who have a severe infectious syndrome with visceral , especially lung , involvement . if recent infection with t. gondii is diagnosed , a potent antitoxoplasmosis treatment ( sulfadiazine plus pyrimethamine ) must be prescribed without delay .
from 1998 through 2006 , 44 cases of severe primary toxoplasmosis were observed in french guiana in immunocompetent adults . 
 toxoplasma gondii isolates exhibited an atypical multilocus genotype . 
 severe disease in humans may result from poor host adaptation to neotropical zoonotic strains of t. gondii circulating in a forest - based cycle .