Gonzalez, Jean-Paul

Rico-Hesse, R.

Thayu, M.

Horizon / Pleins textes

194 
ABSTRACTS 
derived from nest-deposited engorged larvae, may attach to other mice visiting the nest during the 
following spring or summer. Additionally, non-fed nymphs that had detached from mice may 
parasitize other mice visiting that nest. Either interaction is likely to incease the capacity of the vecto 
to transmit zoonotic agents by intensifying host-vector contact. Thus, mouse nests serve as potential 
venues for transmission of certain tick-borne pathogens. 
179 SPECIES CONCEPTS AND IXODES TICKS. Telford SR". Department of Tropical Public 
Health, Harvard School of Public Health, Boston, MA. 
A recently published analysis of the status of the northern deer tick, lxodes dnmnziwi, illustrates the 
problems of defining a species in parasite systems. Morphological, karyotypic, and molecular 
evidence, synthesised with hybridisation data, indicated that the main vector of Lyme disease in the 
United States is a northern population of I. scrrpularis, the blacklegged ticks (Oliver et al. 1993). Such i 
comprehensive report was considered to be definitive, and synonymy of the 2 species was 
recommended. Scrutiny of the presented evidence indicates that such an action is unwarranted. 
Hybridisation evidence, in particular, was considered to be conclusive. Absence of fertile hybrids is 
evidence for isolation. But, the converse, often used as evidence for conspecificity, is at most 
inconclusive (Mayr 1963). At any rate, unpublished evidence documents asymmetrical fertility 
(Gowan and Oliver 1978) between the 2 ticks. Morphological analyses obscured relevant taxonomic 
characters, and ignored the possible presence of mixed populations in geographically intermediate 
sites. Molecular evidence was erroneously interpreted with an insect "clock'. Elegant experiments 
that were not emphasised indicated asymmetry in mate choice, suggesting that a specific mate 
recognition system (SMRS; Paterson 1980) and thus some isolation has been achieved. These 
considerations, coupled with behavioral distinctions that reduce the vectorial capacity of I .  scnyulnrk, 
suggest that these Ixodes species are not conspecific. The biological species concept shall be discussed 
in the light of recent concepts in evolutionary theory, and related to issues in parasitology and public 
health entomology, 
180 
SOUTH AMERICA, Gonzalez JP*, Thayu M, and Rico-Hesse R. 
Scientifique pour le Développement en Coopération, Paris, France; and Department of Epidemiolo 
and Public Health, Yale School of Medicine, New Haven, CT. 
There are now five arenaviruses recognized as pathogenic for humans in the Americas: Junín, 
Machupo, Flexal, Guanarito and SPH114202. In the 1960's, two arenaviruses had been shown to ca 
disease in humans in the Americas, Junín and Machupo. Flexal virus, isolated in 1975, appeared to 
mildly pathogenic for humans, after a laboratory infection. In 1989, Venezuelan hemorrhagic feve 
caused by Guanarito virus, was first detected. 105 presumed cases and 26 deaths were reported by 19 
and several strains isolated from humans and rodents. In 1991, two cases, including one fatality, 
Brazilian hemorrhagic fever have been documented and one virus strain identified, SPH114202. 
studied the molecular epidemiology and origin of these two last emerging arenaviruses by com 
them genetically to others from the Americas. We obtained nucleotide sequences (by primer 
extension of the viral S-RNA segment) of 8 of the 12 arenaviruses circulating in the Americas 
determine their phylogenies. Guanarito virus and the SPH114202 strains were genetically 
(approx. 30% of divergence) from other human arenaviruses. This support the hypothesis 
viruses have been evolving independently in their endemic focus, for some time. Specific 
tools (PCR/oligonucleotide probes) have been developed for clinical and epidemiological stuai 
These reagents allow for a rapid identification of these viruses, without the need for biological 
amplicfication. 
PHYLOGENY OF TWO EMERGING HUMAN PATHOGENIC ARENAVIRUSES FROM 
Institut Franais de Recherche 
PROGRAM AND ABSTRACTS OF THE 
JOINT ANNUAL MEETING 
OF THE AMERICAN SOCIETY OF 
TROPICAL MEDICINE AND HYGIENE 
AND THE AMERICAN SOCIETY OF 
PARASISOLQGBSTS 


Program and abstracts of the joint annual meeting of the American society of tropical medicine and hygiene and the American society of parasitologists : abstracts

Program and abstracts of the joint annual meeting of the American society of tropical medicine and hygiene and the American society of parasitologists : abstracts

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