[Popular nosology of infantile diseases in West Côte-d'Ivoire and consequences for malaria care management]. / Nosologie populaire des maladies infantiles dans l'Ouest de la Côte-d'Ivoire. Implications pour le paludisme.

In a rural area of intense and permanent malaria transmission in Southwest Côte-d'lvoire, traditional midwifes of the Yacouba ethnic group, with also an important function for the children health and care, were interviewed in 2002 about their knowledge of the infantile pathologies. Their nosology is greatly based on symptoms and etiologic explanations of the disorder of secretions. The accumulation of a viscous liquid in different parts of the body, especially in the chest, the throat or the head, explains numerous febrile or afebrile diseases, including malnutrition. Some pathologies, particularly convulsions, are described by analogy with animals behaviour Relations between these entities and the biomedical ones are difficult to establish. The traditional care and treatments result from these concepts. A vomiting child or a child suffering from diarrhoea is subject to devices to evacuate his excess of liquid. Yellow brews are used against jaundice. Furthermore, an important mistrust remains towards medical treatments particularly for all parenteral therapies. Health facilities are only used as a the last resort. Their bad reputation is confirmed by the high rate of mortality of patients coming often too late. To improve malaria care management, health-care workers have to take into consideration these concepts and also prove their abilities to ensure good medical practices.

[Therapeutic efficiency of chloroquine in the savannah region in the north of Côte d'Ivoire (1997)]. / Efficacité thérapeutique de la chloroquine en région de savane du nord de la Côte d'Ivoire en 1997.

We evaluated from August to December 1997 the therapeutic effect of chloroquine (CQ) in treatment of mild malaria. Five villages of the savannah area of Côte d'Ivoire were selected for this study In this area and season, the transmission of malaria is of hyper-endemic type. The 14-day protocol of WHO was used and all the patients were treated with CQ 25 mg/kg over three days. 360 febrile children between 6 and 83 months old out of 545 were selected, and 286 were fully followed. At the beginning of the study axillary temperatures and parasitemia showed no difference in the 5 villages. The average therapy failure rate was 11.5% (IC to 95%; 7.8-15.2) with a maximum of 18.5%. The failure rates estimated in the various villages showed a hardly significant difference (p = 0.05). In the North of Côte d'Ivoire, the good efficiency of CQ can be explained by the low drugs pressure related to the behaviour of populations who use traditional phytotherapy in first resort to treat the fevers.

Inland valley rice production systems and malaria infection and disease in the savannah of Côte d'Ivoire.

In sub-Saharan Africa, lowlands developed for rice cultivation favour the development of Anopheles gambiae s. l. populations. However, the epidemiological impact is not clearly determined. The importance of malaria was compared in terms of prevalence and parasite density of infections as well as in terms of disease incidence between three agroecosystems: (i) uncultivated lowlands, 'R0', (ii) lowlands with one annual rice cultivation in the rainy season, 'R1' and (iii) developed lowlands with two annual rice cultivation cycles, 'R2'. We clinically monitored 2000 people of all age groups, selected randomly in each agroecosystem, for 40 days (in eight periods of five consecutive days scheduled every 6 weeks for 1 year). During each survey, a systematic blood sample was taken from every sick and asymptomatic person. The three agroecosystems presented a high endemic situation with a malaria transmission rate of 139-158 infective bites per person per year. The age-standardized annual malaria incidence reached 0.9 malaria episodes per person in R0, 0.6 in R1 and 0.8 in R2. Children from 0 to 9-year-old in R0 and R2 had two malarial attacks annually, but this was less in R1 (1.4 malaria episodes per child per year). Malaria incidence varied with season and agroecosystem. In parallel with transmission, a high malaria risk occurs temporarily at the beginning of the dry season in R2, but not in R0 and R1. Development of areas for rice cultivation does not modify the annual incidence of malarial attacks despite their seasonal influence on malaria risk. However, the lower malaria morbidity rate in R1 could be explained by socio-economic and cultural factors.

[The epidemiology of malaria in the southwestern forests of the Ivory Coast (Tai region)]. / Epidémiologie du paludisme dans le sud-ouest forestier de la Côte d'Ivoire (région de Taï).

An epidemiological study on malaria was undertaken between July 1995 and July 1996 in two villages (Zaïpobly and Gahably) and their encampments (Kouassikro, Hamanikro and Konankro), in the south-western forest area of Côte d'Ivoire (region of Taï). The parasitological scheme comprised a total of 2023 tests performed on children aged from 0 to 14 years. The species found were Plasmodium falciparum, P. malariae and P. ovale with a proportion of 84%, 14% and 2% respectively. The global parasite prevalence of all Plasmodium species was 85% and malaria was holoendemic. The average parasitic density decreased progressively as the age increased, in contrast to the plasmodic index which did not vary. All the malarial indexes were similar in the villages and their encampments. Only overall fever prevalence was permanent and in all age groups it was higher in the encampments than in the villages. The entomological findings showed that transmission was permanent and intense throughout the year, with a recrudescence during the rainy season. Transmission was attributed to Anopheles gambiae s.l. in 85% of the cases whereas An. funestus played a secondary role. The average sporozoïtic index was 7.6% and varied between 1.1% and 16.7%. The entomological inoculation rate was of 400 infected bites per person-year for An. gambiae s.l. In such conditions of intense transmission, acquisition of premunition starts at a very early age. This assertion is verified by the average parasite density and the frequency of high parasitic densities which were at their maximum between 1 and 4 years of age and decreased thereafter as the age increased. The paludometric and entomologic indexes obtained are the most elevated ever to have been observed in Côte d'Ivoire, as a result of considerable ecological changes linked to the deterioration of the forest environment over the past 30 years. This deterioration has probably been caused by demographic pressure resulting from internal and foreign immigration to the Taï region and more especially by the influx of Liberian refugees.

[Efficacy of permethrin-impregnated Olyset Net mosquito nets in a zone with pyrethroid resistant vectors. I--Entomologic evaluation]. / Efficacité des moustiquaires pré-imprégnées de perméthrine Olyset Net en zone de résistance des vecteurs aux pyréthrinoïdes. I--Evaluation entomologique.

The efficacy of permethrin-treated Olyset Net mosquito nets on malaria transmission and morbidity was studied in Kafine, a village located in the savanna region of the Cote d'Ivoire in Africa. After collecting sociodemographic, entomological, and parasitological data, bednets were distributed first in the southern half of the village and then in the whole village. Throughout the study period, mosquito specimens were captured on the skin of inhabitants at four points in the village between 6 PM and 6 AM both inside (but outside bednets) and outside houses. Prior to distribution of bednets, the mean biting rate (MBR) by Anopheles gambiae was 77.4 bites per man per night (b/m/n). The mean parturity rate (MPR) was 40.6 p. 100, the sporozootic index (SI) was 0.99 p. 100, and the mean entomological inoculation rate (MEIR) was 0.7 infectious bites per man per night (b+/m/n). Six months after distribution of bednets in the southern half of the village, MBR was 80.2 b/m/n, MPR was 32 p. 100, SI was 1.8 p. 100, and MEIR was 0.83 b+/m/n. After extending distribution to the whole village, data from November 1996 to July 1997 were as follows: MBR, 67.8 b/m/n; MPR, 20.1 p. 100; SI, 0.65 p. 100; and MEIR, 0.66 p. 100. From August 1977 to July 1998, data were as follows: MBR, 102.6 b/m/n; MPR, 26.2 p. 100; SI, 1.15 p. 100; and MEIR, 0.74 b+/m/n. Comparative analysis of these data showed that use of bednets had no effect on the bite or entomological inoculation rate. This is in agreement with the documented resistance of vectors in the study zone to permethrin. Despite the known stimulation/repulsion effect of permethrin, use of treated bednets had no real impact on transmission. This inefficacy could be related to the high prevalence (80 p. 100) of the Kdr gene (responsible for resistance) in the savanna form of Anopheles gambiae.

[Efficacy of permethrin-impregnated Olyset Net mosquito nets in a zone with pyrethroid resistance vectors. II. Parasitic and clinical evaluation]. / Efficacité des moustiquaires pré-imprégnées de perméthrine Olyset Net en zone de résistance des vecteurs aux pyréthrinoïdes. II. Evaluation parasitoclinique.

The efficacy of permethrin-treated Olyset Net mosquito nets in preventing transmission and morbidity of malaria was studied in Kafine, a village in the rice-growing region of the Cote d'Ivoire. Entomological data demonstrated that permethrin-treated mosquito nets failed to reduce transmission of malaria. Laboratory tests showed that Anopheles gambiae s.s. in Kafine were resistant to permethrin and other pyrethroids. Study included a cohort of 163 children under five years of age who did or did not use mosquito nets. The number of patients seeking treatment for malaria attacks with fever was recorded weekly. No difference was found between the user and non-user groups with regard to the percentage of children exhibiting Plasmodium flaciparum trophozoites or gametocytes or to the mean parasite load. However the rate of high density parasitemia and malaria attacks was twice as high in the non-user group. This difference between users and non-users of mosquito nets cannot be explained only as the result of a physical barrier against bites. In areas where mosquitoes are resistant to pyrethroids, tests conducted in experimental huts have shown that impregnated mosquito nets reduce host/vector contact. However further study will be need to evaluate the overall impact of impregnated nets on malaria in the areas where mosquitoes are resistant to insecticides.