[Integration of demographic factors in the characterization of risk areas for sleeping sickness in Côte d'Ivoire]. / Intégration des facteurs démographiques à la caractérisation d'un espace à risque de maladie du sommeil en Côte d'Ivoire.

The purpose of this study was to classify the risk for transmission of African human trypanosomiasis (sleeping sickness) according to population and settlement densities in four different areas of Zoukougbeu, Cote d'Ivoire, where the exact location of cases reported since 1990 is known. Epidemiological risk indexes were calculated from entomological data obtained from three surveys and analyzed with respect to presence of patients and occupancy rate in each area. Results indicated that there was a risk of transmission near the village of Bahigbeu II where the population density is between 30 and 40 inhabitants per km2 and settlement density is 4 per km2. There was also a risk in less inhabited areas such as Ouatigbeu where the population density is less than 30 inhabitants per km2 and dwelling density less than 4 per km2. In fact, cases are regularly reported in Ouatigbeu but never in Bahigbeu II. Based on these findings, we conclude that, while land occupancy can be considered as a risk factor for sleeping sickness, other factors such as human mobility must be taken into account to characterize risk areas and predict outbreaks.

[Incidence of African trypanosomiasis and the density of settlements in the forests of Côte d'Ivoire: the possibility of predicting high risk areas for surveillance of disease reservoirs]. / Incidence de la maladie du sommeil et densité des campements de culture en forêt de Côte d'Ivoire: possibilité de prédiction des zones à risques pour la mise en place précoce d'un réseau de surveillance.

In the forests of Côte d'Ivoire a surveillance network is needed to quickly and continuously detect cases of Human African Trypanosomiasis (HAT). This requires knowledge of high risk areas, and thus of an appropriate epidemiological indicator. Study of several HAT foci in Côte d'Ivoire shows a striking correlation between epidemiological risk and settlement density by square kilometer (r = 0983; P < 0.05). Epidemiological risk and disease incidence will increase up to the point when human influence eradicates the vector. This hypothesis is supported by the correlation between settlement density (d) and cumulative incidence: i = 0988 d - 0967 (r = 0.951). The prevalence would be 0.5% from 1.5 settlements per km2, and 1% from a density of 2. The first results of remote sensing indicate that it is possible to identify forest areas where settlement density has reached a critical level.

[Detecting sleeping sickness: comparative efficacy of mobile teams and community health workers]. / Dépistage de la maladie du sommeil: efficacité comparée des équipes mobiles et des agents de santé communautaires.

The solution to the problem of human African trypanosomiasis (HAT) first of all requires improved case detection. Effective tests have been available for a number of years but the results of medical surveys are still mediocre, mainly because the populations are poorly mobilized. Those few mobile teams still visiting villages obtain very low presentation rates. In spite of major information campaigns among villagers, in Côte d'Ivoire the Institut Pierre Richet (IPR) and Trypanosomiasis Clinical Research Project (PRCT) teams examined only 42% (9311) of the 22,300 inhabitants of a disease focus during a conventional ten-day survey. In the same focus, community health workers specially trained in sleeping sickness and in the collection of blood samples on filter-paper examined 73% of the population (15,000 individuals) in less than two months. Implementation of a sleeping sickness control strategy is restricted to two types of intervention: either conventional mobile teams which are on hand, competent and rapidly operational but which fail to carry out exhaustive case detection, or integration of case detection into primary health care by entrusting surveillance to the community health workers. This approach requires a minimum of training but ensures that sentinels are permanently present in the village communities. By using the community health workers rather than mobile teams it should be possible to achieve comprehensive monitoring. In operational terms, the cost of surveillance per person is US$ 0.55 for the mobile teams as against US$ 0.10 for the community health workers. Integration of HAT case detection into primary health care is therefore an effective and economical solution, provided the community health workers are properly supervised and above all motivated.

[Epidemiologic risk of infectious disease transmission in regions of the Ivory Coast]. / Le risque epidemiologique dans un foyer de maladie du sommeil en Cote d'Ivoire.

An epidemiological risk indicator based on purely entomological factors can be used to identify regions which are at higher risk of transmission within the endemic forest zones of Ivory Coast, and can serve to point out biotopes to be treated to make antivector campaigns more effective. In the forests of Ivory Coast, so-called socially open environments which are populated by a great number of ethnic groups who are highly mobile and whose amps are spread over a large area, are particularly vulnerable to epidemics of the disease. Transmission always occurs near water: at rivers, water holes, plantations. By contrast, socially closed societies consisting of a single ethnic group settled in a village are at much lower risk. It seems that human behaviour plays as much a role in transmission dynamics as environmental changes which may be more or less favourable to the vector.

[Evaluation of the parasitologic technics used in the diagnosis of human Trypanosoma gambiense trypanosomiasis in the Ivory Coast]. / Evaluation des techniques parasitologiques utilisées dans le diagnostic de la trypanosomose humaine a Trypanosoma gambiense en Côte-d'Ivoire.

The investigators carried out a comparative evaluation of twelve or parasitological techniques used nowadays in the diagnosis of human trypanosomiasis and parasite isolation in the lymph fluid, blood and cerebro-spinal fluid (CSF). The tests were performed on 64 seropositive suspects selected with TESTRYP-CATT among 661 attendants examined at the Projet de Recherches Cliniques sur la Trypanosomiase (PRCT), Daloa, Côte-d'Ivoire. The study showed that the sensitivity of the different techniques varies between 17.2% (for CSF inoculation to Mastomys) and 84.5% (for the anion exchange centrifugation technique-mAECT). The classical techniques, says lymph fluid examination, direct blood examination and thick blood have a sensitivity of 58.6, 22.4 and 34.5% respectively. The most sensitive methods are lymph fluid examination, mAECT and double centrifugation of CSF (69%). The sensitivity increases up to 98.3% with the combination of two or three techniques. The combination of lymph fluid examination/mAECT/double centrifugation of CSF is either the most sensitive and the most suitable one for use in the field. The combination of lymph fluid examination and mAECT which detects 91.4% of the infected subjects is the most efficient. The authors discussed the results and recommended that similar study be done in field conditions to assess methods which either demonstrated better sensitivity and are more suitable for field use.

[Risk factors for human African trypanosomiasis in the endemic foci of Ivory Coast]. / Les facteurs de risque de la trypanosomiase humaine africaine dans les foyers endemiques de Cote d'Ivoire.

A case-control study on risk factors of Trypanosoma brucei gambiense human african trypanosomiasis was carried out in 111 patients diagnosed in the three main foci of Ivory coast. Each case was age and sex matched with one seronegative control living in the same locality. Based upon previous epidemiological surveys conducted in similar areas, the potential risk factors were identified and assessed using a standard questionnaire. The study demonstrates that in the forest area of Ivory coast human trypanosomiasis in a behavioral disease affecting mainly coffee and cocoa farmers. The allogenous populations coming from sudano-sahelian savannah are more exposed to the disease than other ethnic groups. People sleeping at the farm (encampments) are more likely to become infected than those living at the village (ODDS-Ratio = 4.5). People fetching water in natural holes and pools have an increased risk (ODDS-Ratio = 3.6). Cases reported more often than controls that they are foodstuffs dealers from the farms to the villages (ODDS-Ratio = 13.0). These results are consistent with data from previous studies. We identified preventable risk factors, upon which interventions should be carried out to reduce the incidence of the disease. The possibility of using these findings to improve sleeping sickness control programme in the forest areas of Ivory Coast is discussed.

[Prevalence of asthma and respiratory diseases in schools in Bouake (Ivory Coast): preliminary results]. / Prévalence de l'asthme et des maladies respiratoires en milieu scolaire à Bouake (Côte d'Ivoire): résultats préliminaires.

Using an auto-administered questionnaire, a cluster sample survey was carried out in January 1990 among 2433 secondary schoolchildren in Bouake (Cote d'Ivoire). The prevalence rate of asthma was fairly high (10.8%), as well as that of wheezing (19.8%), dyspnea (42.8%), broncho-pulmonary diseases (25.8%) and smoking habit (14.5%). The results are discussed with regard to the published data.