**3. Results**

158 Current Topics in Tropical Medicine

1988). Thirdly, some of the females belonging to the *An. gambiae* complex were identified to species level, in a PCR-based assay (Scott et al., 1993). Finally, some of the mosquitoes belonging to the *An. funestus* group were further identified using an assay based on a

Repeated cross-sectional surveys were carried out in the study villages to assess malaria parasitaemia and clinical malaria in children aged ≤15 years. The first survey was done in June 2002. In 2003, two surveys were carried out in Zatta and three in Tiémélékro. The research team first worked in the primary schools and all children aged between 7 and 15 years from randomly selected classes were invited for a finger prick blood sample. Next, mothers and caregivers of under 7-year-old children were invited to accompany their children to a designated community location where a blood sample was taken from each

Thick and thin blood films were prepared on microscope slides. The slides were air-dried prior to transfer to a nearby laboratory where they were stained with Giemsa for 45 min. The slides were examined by the same experienced laboratory technician throughout the study under a microscope at high magnification. *Plasmodium* species and gametocytes were identified and counted against 200 leucocytes. When less than 10 parasites were found, reading was continued for a total of 500 leucocytes. Parasitaemia was expressed by the number of parasites per µl of blood, assuming for a standard count of 8000 leucocytes/µl blood. For quality control, 10% of the slides were randomly selected and re-examined by a

In our study, fever was defined when an individual had an axillary temperature >37.5 ◦C. Clinical malariawas defined as fever plus parasitaemia (Smith et al., 1994). Particular emphasis was placed on clinical cases with a parasitaemia >5000 parasites/\_l blood. The latter threshold has been chosen after comparing the proportions of fever cases and asymptomatic carriers for different classes of parasite density (Gaye et al., 1989). Subjects with malaria-related symptoms (e.g. headache) plus axillary temperature >37.5 ◦C were given artesunate plus amodiaquine (the respective first-line antimalarial treatment at the

The study protocol was approved by the institutional research commission of the Centre Suisse de Recherches Scientifiques (Abidjan, Côte d'Ivoire). Ethical clearance was obtained from the Ivorian Ministry of Public Health and National Malaria Control Programme. People who acted as bait and collectors in the mosquito collections were all volunteers and signed informed consent forms. During the study, Patients with malariarelated symptoms who presented at the dispensaries and mosquitoes' collectors were treated and protected for free against malaria by artesunate–amodiaquine chemoprophylaxis (artesunate–amodiaquine being the recommended, first-line treatment for malaria in Côte d'Ivoire at the time of the present study) and all mosquitoes' collectors were immunized against yellow fever. The heads of household in both study sites were informed and the parents or legal guardians of participating children signed a written

multiplex PCR (Koekemoer et al., 2002; Cohuet et al., 2003).

**2.1.4 Clinical and Parasitological surveys** 

child.

second senior technician.

**2.1.5 Ethical issues** 

informed consent sheet.

time of the study) and paracetamole.
