Tsetse elimination: its interest and feasibility in the historical sleeping sickness focus of Loos islands, Guinea.

Guinea is the West African country which is currently the most prevalent for sleeping sickness. The littoral area is the region where most of the recent sleeping sickness cases have been described, especially the mangrove sleeping sickness foci of Dubreka and Boffa where Glossina palpalis gambiensis is the vector. Loos islands constitute a small archipelago 5 km apart from the capital, Conakry. Medical, animal, and entomological surveys were implemented in these islands in Oct-Nov 2006. No pathogenic trypanosomes were found in these surveys. The locally very high tsetse densities (up to more than 100 tsetse/trap/day) linked to pig rearing, constitute a high potential risk for humans (taking into account populations movements with neighboring active sleeping sickness foci of the Guinea littoral, and the history of sleeping sickness on these islands), and for the economically important pig rearing, as well as a danger for tourism. This situation, associated to the possibility of elimination of these tsetse populations due to low possibility of reinvasion, led the National Control Program to launch a tsetse elimination project following an "area wide" strategy for the first time in West Africa, which participates in the global objective of the PATTEC (Pan African Tsetse and Trypanosomosis Eradication Campaign).

[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.

Impact of the development of agricultural land on the transmission of sleeping sickness in Daloa, Côte d'Ivoire.

Although tools to control sleeping sickness do exist, their use is difficult; areas where intervention is most required often cannot be targeted for lack of appropriate risk indicators. The importance of human behaviour and habits in the manifestation of the disease is clear. In the development of effective new approaches to the control of the disease, information must be gathered about human populations, and their interaction with the environment, in rural as well as in urban and peri-urban areas. The results of a study carried out in Daloa show that use of some methods for the development of agricultural land leads to increased human-vector contact and, as a result, increased risk of sleeping sickness. Such land-management methods may therefore be useful as risk indicators for transmission. Transmission does not occur in the town of Daloa itself but in surrounding areas under cultivation. The use of the epidemiological risk index seems to be inappropriate in urban (and perhaps peri-urban) areas. The results emphasise not only the importance of environmental and demographic data in elucidating the epidemiology of human trypanosomiasis but also the need for further investigations in peri-urban areas.

Effects of urbanization on transmission of human African trypanosomiasis in a suburban relict forest area of Daloa, Côte d'Ivoire.

The epidemiological risk of human African trypanosomiasis transmission was evaluated from entomological parameters (apparent trap density, female teneral rates, daily survival rates, proportion of human feeds) of tsetse (Glossina palpalis palpalis) populations in the town of Daloa, Côte d'Ivoire. High tsetse densities were found in the town outskirts, where the calculated risk of transmission was greatest. Environmental changes brought about by urbanization did not result in the disappearance of tsetse, or the interruption of sleeping sickness transmission. The few cases of sleeping sickness detected (32) in the years 1990-95 indicated that transmission was unrelated to tsetse density.

[Geographic approach to urinary schistosomiasis in an average African town, Daloa (Ivory Coast)]. / Approche géographique de la schistosomiase urinaire dans une ville moyenne africaine, Daloa (Côte d'Ivoire).

Agricultural activity occurs within many medium size towns in developing countries. Rural influences and urbanization, which may be well or poorly managed, combine to create new health problems. A geographical approach is useful for evaluating the ability of the health care system to deal efficiently with these problems. Such an approach should take into account the urban environment and human population, health care and spatial differentiation factors. Relevant health indicators were selected to analyze the geographical patterns of health risk and of the health care system. These factors were analyzed according to area, at various levels. Field studies were carried out and aerial photographs and the various available maps were also studied. Results were compared to determine whether the health care system was appropriate for the health needs of the town. Urinary schistosomiasis is a useful example for assessing the value of the suggested methodology. The risk of transmission of this disease is high so its early detection is vital. The ability of the health care system to detect infection was assessed.

[Contribution to studies on the modern health care system in the Republic of Congo: geographical approach]. / Contribution aux études sur le système de soins modernes en République du Congo: approache géographique.

We carried out a geographic analysis of the modern health care system in the rural areas of Kouilou and Niari (Republic of Congo). Spatial differences in physical (e.g. vegetation, relief) and human (social and demographic profiles) factors must be characterized because they have an effect on the organization and spatial distribution of the health care system. The location of health care structures depended on the structure of the local environment. The health care system seemed primarily to be a component of the economic development determining population distribution in the forest area. In the savannah, it was part of the local administrative framework, the key factor determining the structure of the local space. Health care services were most used in areas with average to large population densities, in which there were the largest number of health care structures. Areas with "marginal" population densities and health care center distributions had the lowest rates of health care use. Health care zones can be defined by considering geographical characteristics and the characteristics of the health care system. This makes health planning (e.g. opening of health centers, improvement of health centers) much easier to undertake.

Determination des zones a risque de trypanosomiase humaine; application au controle et a la lutte pour une valorisation des acquis scientifiques

Depuis des annees; on a demontre que le piegeage est la seule technique utilisable pour la lutte contre les glossines; en utilisant la force de travail des communautes rurales; sous la supervision d'une equipe restreinte. Mais malgre les efforts des entomologistes pour reduire les couts de la lutte antivectorielle; ceux-ci sont difficilement supportables pour des etats africains concernes par la trypanosomiase humaine africaine. Ce travail de lutte serait certainement efficace s'il etait base sur un systeme d'information geographique et la teledetection. Ces derniers permettent en effet de caracteriser precisement les principaux foyers endemiques; d'extrapoler les resultats a l'ensemble d'une zone biogeographique et de prevoir la localisation des futures zones a risques

Gestion de l'espace et maladies liees a l'environnement : cas de l'Afrique de l'Ouest

L'environnement peut etre incrimine de bien des facons dans l'existence de pathologies tropicales. Les interactions peuvent expliquer les phenomenes sanitaires a l'echelle de la transmission dans le cadre de l'environnement compris comme un systeme. Il ne s'agit pas de nier le role des facteurs qui conditionnent l'existence du vecteur dynamique. Par contre au sein d'une zone d'endemicite ce sont les comportements et donc la gestion de l'espace qui vont provoquer des disparites face au risque sanitaire

[Mobility in the Sahel, especially in the triangular frontier area covering parts of Mauritania, Senegal, and Mali]. / Mobilite sahelienne dans le triangle frontalier Mauritanie-Senegal-Mali

PIP: Migration trends in the frontier area of Mauritania, Senegal, and Mali are described. Data on migration in colonial times are used as an introduction to the study of more recent migration streams between the independent states of the region.^ieng