Jean-François Molez

Impact of chloroquine resistance on malaria mortality

Over 12 years, from 1984 to 1995, we conducted a prospective study of overall and malaria specific mortality among three rural populations in the Sahel, savanna and forest areas of Senegal. The emergence of chloroquine resistance has been associated with a dramatic increase in malaria mortality in each of the studied populations. After the emergence of chloroquine resistance, the risk of malaria death among children 0-9 years old in the three populations was multiplied by 2.1, 2.5 and 5.5, respectively. This is the first study to document malaria mortality at the community level in Africa before and after the emergence of chloroquine resistance. Findings suggest that the spread of chloroquine resistance has had a dramatic impact on the level of malaria mortality in most epidemiological contexts in tropical Africa.

Evaluation of anti-Plasmodium falciparum antibodies in Senegalese adults using different types of crude extracts from various strains of parasite

To date, no consensus exists on the type of crude Plasmodium falciparum Ags to be used in a standard assay for the evaluation of the overall anti-blood-stage immune response in humans. Comparison of the dose-dependent reactivity of using a pool of hyper-immune Senegalese sera to saponin and water schizont extracts of the Senegalese 07/03 isolate indicated similar reactivity on both types of antigen preparations. Water schizont extracts from three different strains of P. falciparum adapted to in vitro culture probed with a panel of specific mouse antisera and monoclonal antibodies reacting with conserved antigens showed similar antigenic content. Seroreactivity of immune individuals living in three different areas of endemicity was assessed in parallel on water crude extracts. The individual IgG, IgM and IgG subclass antibody responses to the various schizont preparations correlated positively. The specific IgM response was higher on the Senegalese schizont extract than on the FCR3 extract and was highest in Dielmo villagers. The IgG response was similar in all three locations and was strain independent. These results indicate that monitoring IgG antibody levels to the widely distributed FCR3 strain using an easily prepared crude lysate might represent a valuable reference ELISA allowing homogenisation and comparison of data from different laboratories.

Canine visceral leishmaniasis caused by Leishmania infantum in Senegal: risk of emergence in humans?

In the context of global warming and the risk of spreading arthropod-borne diseases, the emergence and reemergence of leishmaniasis should not be neglected. In Senegal, over the past few years, cases of canine leishmaniasis have been observed. We aim to improve the understanding of the transmission cycle of this zoonosis, to determine the responsible species and to evaluate the risk for human health. An epidemiological and serological study on canine and human populations in the community of Mont Rolland (Thiès area) was conducted. The data showed a high seroprevalence of canine leishmaniasis (>40%) and more than 30% seropositive people. The dogs seroprevalence was confirmed by PCR data (concordance > 0.85, Kappa > 0.7). The statistical analysis showed strong statistical associations between the health status of dogs and seropositivity, the number of positive PCRs, clinical signs and the number of Leishmania isolates. For the first time, the discriminative PCRs performed on canine Leishmania strains clearly evidenced that the pathogenic agent is Leishmania infantum. The results obtained show that transmission of this species is well established in this area. That the high incidence of seropositivity in humans may be a consequence of infection with this species is discussed.