Additional Haplogroups of Toxoplasma gondii out of Africa: Population Structure and Mouse-Virulence of Strains from Gabon

Prevalence of human toxoplasmosis in tropical African countries usually exceeds 50%. Its role as a major opportunistic infection of AIDS patients is regularly described. Due to the lack of investigation, congenital infection is certainly underestimated in Africa. Incidence of Toxoplasma ocular disease is higher in Africa and South America than in Europe. Severe cases in immunocompetent patients were described after infection acquired in Amazonia, but nothing is known about such cases in Africa. Several studies argued for a role of genotypes in the clinical expression of human toxoplasmosis, and for a geographical structuration of Toxoplasma across continents. Genetic data concerning isolates from Africa are scarce. Here, apart from the worldwide Type III, we described two main haplogroups, Africa 1 and 3. We detected genetic exchanges between urban centers favored by trade exchange and transportation. It shows how important human influence is, even in shaping the genetic structure of a zoonotic disease agent. Finding of identical haplogroups in South America suggested that these African and American strains share a common ancestor. As a higher pathogenicity in human of South American genotypes has been described, this similarity of genotypes should encourage further clinical studies with genotype analysis in Africa

Orienting and alerting: effects of 24 hours of prolonged wakefulness.

It is well known that a decrease in vigilance can easily occur during 24 h of continuous wakefulness, but no study has assessed whether and in what way extended wakefulness might affect spatial orienting. In other words, it is not clear what happens when a subject has to orient his attention during a state of poor vigilance, resulting from sleep loss or sustained wakefulness. The aim of this study was to investigate this issue. Twelve right-handed male subjects participated in the experiment, which took place on two consecutive days. On the first day, in order to evaluate baseline orienting attention, the subjects performed a covert orienting task (in which the cue stimuli generated endogenous shifts of attention), lasting 20 min; on the second day, during 24 h of prolonged wakefulness, the same task was performed 12 times, about every 120 min, beginning at 10.00 a.m. Results showed an overall slowing of reaction time across the sessions, indicating a linear decrease of vigilance. However, this vigilance decrease did not seem to affect attention-orienting mechanisms, suggesting that the two systems are independent of each other