The COVID-19 pandemic in francophone West Africa: from the first cases to responses in seven countries.

BACKGROUND: In early March 2020, the COVID-19 pandemic hit West Africa. In response, countries in the region quickly set up crisis management committees and implemented drastic measures to stem the spread of the SARS-CoV-2 virus. The objective of this article is to analyse the epidemiological evolution of COVID-19 in seven Francophone West African countries (Benin, Burkina Faso, Côte d'Ivoire, Guinea, Mali, Niger, Senegal) as well as the public health measures decided upon during the first 7 months of the pandemic. METHODS: Our method is based on quantitative and qualitative data from the pooling of information from a COVID-19 data platform and collected by a network of interdisciplinary collaborators present in the seven countries. Descriptive and spatial analyses of quantitative epidemiological data, as well as content analyses of qualitative data on public measures and management committees were performed. RESULTS: Attack rates (October 2020) for COVID-19 have ranged from 20 per 100,000 inhabitants (Benin) to more than 94 per 100,000 inhabitants (Senegal). All these countries reacted quickly to the crisis, in some cases before the first reported infection, and implemented public measures in a relatively homogeneous manner. None of the countries implemented country-wide lockdowns, but some implemented partial or local containment measures. At the end of June 2020, countries began to lift certain restrictive measures, sometimes under pressure from the general population or from certain economic sectors. CONCLUSION: Much research on COVID-19 remains to be conducted in West Africa to better understand the dynamics of the pandemic, and to further examine the state responses to ensure their appropriateness and adaptation to the national contexts.

[Efficacy against Malaria Vectors of Long-Lasting Insecticide-Treated Mosquito Nets after 17 Months of Use in the City of Bouaké, in the Center of Côte d'Ivoire]. / Efficacité contre les vecteurs du paludisme de moustiquaires imprégnées d'insecticide à longue durée d'action après 17 mois d'utilisation dans la ville de Bouaké, au centre de la Côte d'Ivoire.

Malaria remains a public health problem in Côte d'Ivoire despite a 95% coverage rate with long-lasting insecticide-treated mosquito nets (LLINs) since 2015. A study was conducted in Bouaké to determine the residual efficacy of LLINs used during 17 months (N = 30) and of stored and unpacked LLINs (N = 8). The physical integrity of LLINs and their biological efficacy on populations of Anopheles gambiae (sensitive and resistant to insecticides) were assessed. The study revealed that 57% (17/30) of LLINs recovered from households have a hole. The proportional hole indices indicated that 70% (21/30) of LLINs were in good condition, 20% (6/30) were repairable and 10% (3/30) were unusable.This study also showed that the LLINs used and stored were effective on the sensitive Kisumu strain but ineffective on resistant populations of An. gambiae of Bouaké. Average knock-down and mortality rates induced by LLINs used on the populations of An. gambiae from Bouaké were 23% and 9%, respectively. The resistance of mosquitoes to insecticides and the alteration of the physil integrity of mosquito nets are probably major factors to be taken into account in estimating the efficacy of LLINs in the field.

Le paludisme demeure un problème de santé publique en Côte d'Ivoire malgré un taux de couverture en moustiquaires imprégnées à longue durée d'action (MILDA) de 95 % depuis 2015. Une étude a été menée à Bouaké afin de déterminer l'efficacité résiduelle de MILDA utilisées pendant 17 mois (n = 30) et celle de MILDA stockées et non déballées (n = 8). Pour ce faire, l'intégrité physique des MILDA et leur efficacité biologique sur des populations d'Anopheles gambiae (sensibles et résistants aux insecticides) ont été évaluées. L'étude a révélé que 57 % (17/30) des MILDA récupérées dans les ménages sont trouées et que les indices proportionnels de trous les plaçaient dans la catégorie des moustiquaires en bon état pour 70 % (21/30) d'entre elles, réparables pour 20 % (6/30) d'entre elles, inutilisables pour les 10 % (3/30) restants. Cette étude a également montré que les MILDA utilisées et stockées étaient efficaces sur la souche sensible Kisumu, mais inefficaces sur les populations résistantes d'An. gambiae de terrain. Les taux moyens de knock-down et de mortalité induits par les MILDA utilisées sur les populations d'An. gambiae de Bouaké étaient respectivement de 23 et 9 %. La résistance des moustiques aux insecticides et l'altération de l'intégrité physique des moustiquaires sont probablement des facteurs majeurs à prendre en compte dans l'estimation de l'efficacité des MILDA sur le terrain.

[Family environment and dental health disparities among urban children in Burkina Faso]. / Environnement familial et disparités de santé dentaire des enfants en milieu urbain au Burkina Faso.

BACKGROUND: Dental caries is the most common multifactorial disease in children and has substantial negative impact on daily life. In sub-Saharan Africa, few data are available on the relationship between dental caries and the social and family environment of children. The objectives of the present study were firstly to assess the level of prevalence and severity of dental caries of children in Ouagadougou, the capital city of Burkina Faso and secondly to determine whether or not individual factors, family and living conditions are linked with dental health disparities within the population. METHODS: Interview and clinical data were obtained from a household-based cross-sectional survey. A two-stage stratified sampling technique was applied in four areas of Ouagadougou representing different stages of urbanization. RESULTS: The final study population included 1606 children aged 6-12 years. For the overall group the total caries prevalence rate was 48.2%. Results showed that the dental health status of the mother, social integration of the householder and socioeconomic level of the household were associated with the dental health of children. Disparities in dental health were prominent; poor dental health was relatively frequent in children from households poorly integrated into social networks with rather acceptable standard in terms of material wealth. CONCLUSION: Our study showed that individual factors as well as family-related and environmental factors had an influence on their caries experience. The rapidly changing lifestyle affects oral health and the burden of oral diseases is expected to increase initially in people of upper classes and later in disadvantaged people. Disease prevention focussing on common risk factors of chronic diseases should be enhanced. In addition, the accessibility of quality fluoride products (e.g. toothpaste, salt, water) should be facilitated as soon as possible.

[Land-use and urinary schistosomiasis in Daloa (Côte d'Ivoire)]. / Gestion de l'espace et schistosomose urinaire a Daloa (Côte d'Ivoire).

The relation between agricultural land development of inland-valleys and health population has been studied in a town of the Ivorian forest area using urinary schistosomiasis as an indicator. Snails were collected during 4 months in rice fields and water holes used for market gardening of two urban inland-valleys (Batagnihi and Gakognihi). Prevalence of schistosomiasis was evaluated in two districts, Kennedy II and Fadiga, located close to the investigated inland-valleys. Schistosomiasis risk was higher in the Batagnihi where rice cultivation was more developed and prevalence of urinary schistosomiasis was higher in the Kennedy II district which is close to this inland-valley particularly among the Northern migrant people. The Kennedy II population has much more contacts with the inland-valley because of rice cultivation and social status. The higher socio-economic level of the Fadiga population limiting its contacts with the inland-valley can explain this result.

[African towns and health: references and stakes]. / Villes africaines et santé: repères et enjeux.

Urbanization is a fairly recent phenomenon. Thus during the 19th century, only 5% of the population was living in town. However it is more and more important as urban population has been multiplied by 15 since 1900. In Africa, this evolution is still more recent and the continent remains poorly urbanized. But the rate of urbanization is the fastest in the world and demographic forecasts indicate that by 2025, more than 50% of the African population will live in towns. Consequences of urbanization on human development are not well known. Concepts of demographic and epidemiological transitions were widely used for health. Health transition is another concept, including cultural, social and behavioural determining factors as well as ways of caring and being cared for. These processes account for the reduction of infectious diseases through a fall of mortality and birth rates and the emergence of non-transmissible diseases like cardiovascular diseases, cancers, mental diseases.... Although health situation is depicted as better in towns (better immunization, health care offer, better access to health care...), mortality and morbidity patterns seem to change more quickly in towns than in rural areas. However this is not true everywhere in urban areas where several towns are to be found within the same town and for example, health of populations living on margins may be worse than that of rural populations. Urban people resort to modern health care together with traditional healers, even informal, sometimes illegal health care, involving heavy costs but offering no guarantee as regards their quality and their efficiency for patients and society. It appears that developing countries have to face a new health care demand quite different from the one they used to face before, when they have simultaneously to cope with uncontrolled town growth. Under these conditions, urban health should become a priority.

[Role of patient travel in transmission of human African trypanosomiasis in a highly endemic area of the Ivory Coast]. / Représentation spatiale des déplacements des malades dans un foyer de trypanosomose humaine africaine de Côte d'Ivoire.

Human African trypanosomosis (HAT) remains a major public health problem in Subsaharan Africa. The region around the town of Bonon in middle western Côte d'Ivoire is a highly endemic HAT zone. The purpose of this study was to assess the role of travelling of infected patients in transmission of HAT. The study population included a total of 96 patients in whom HAT had been diagnosed actively or passively between 1999 and 2000. Information on each patient's residence and workplaces, i.e. water site, and farm field, was used to calculate the mean distance traveled and mean number of places visited daily by each patient. Findings indicated that both parameters, i.e., distance traveled and number of places visited, were significantly higher for patients living in Bonon than those living in hamlets or homesteads. Based on analysis of patient movements the endemic zone could be divided into three subdivisions with different modes of disease transmission. This study was performed as a preliminary step for a larger investigation designed to allow specific targeting of HAT hot spots based mainly on a geographic information system.

Host age and time of exposure in Trypanosoma brucei gambiense Human African Trypanosomiasis.

Human African Trypanosomiasis is related to behavioural risk factors but complex interactions exist between (i) environmental and behavioural risk factors, (ii) vector and (iii) human host. Our aim was to investigate the interrelationships between previously analysed risk factors and the roles of age and time of exposure according to ethnic group and migration status. However, this descriptive and retrospective study is based on cases only (no controls) and our results must therefore be regarded as hypothesis-generating. Individuals originating from areas where sleeping sickness is absent and who settle in an endemic area seem to develop the disease after a shorter time of exposure than native subjects from endemic areas. Our results emphasise the complexity of vector-transmitted disease epidemiology, involving behavioural and/or environmental risk factors on the one hand, and more individual ones such as ageing, immunity and genetic background on the other hand.

[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.

[Age group distribution of Glossina palpalis palpalis females in plantations and shallow water of the forest region of Côte d'Ivoire. Relation to the prevalence of sleeping sickness]. / Répartition des groupes d'âge de Glossina palpalis palpalis femelle dans les plantations et les talwegs en zone forestière de Côte d'Ivoire. Relation avec la prévalence de la maladie du sommeil.

In epidemiologically dangerous biotopes of foci with high prevalence of Human African Trypanosomiasis (HAT), different female age groups (nulliparous, young parous, old parous) were observed in the same proportions. On the contrary, in areas without HAT or in low prevalence foci (< 0.2%), these proportions significantly differed. Female age group distribution in epidemiologically dangerous biotopes could thus be a good indication by which to guide the control of Human African Trypanosomiasis (HAT).

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

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.

[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.

Effects of two insect growth regulators on the susceptibility of Aedes aegypti (Diptera:Culicidae) to Molinema dessetae (Nematoda:Filarioidea).

The effects of 2 growth regulators, diflubenzuron (DFB) and OMS 2017, on the ability of females Aedes aegypti to become infected with Molinema dessetae was studied under laboratory conditions. OMS 2017 and DFB had no effect on either the amount of blood ingested or the microfilarial load. The infective potential of females that survived DFB treatment was significantly greater than untreated females, but there was no difference between OMS 2017-treated and control females. The percentage of infective larvae in the head after OMS 2017 and DFB treatments was significantly greater than for control females. Insect growth regulators appear to affect the vectorial competence of mosquitoes, and these results indicate the need for preliminary studies before these compounds are used in large-scale control programs.

A FORTRAN program to simulate the evolution of genetic variability in a small population.

This paper presents a FORTRAN-77 program that performs Monte Carlo simulation of the evolution of genetic structure in a small population under selection. The aim is to study the possibility of foreseeing a response plateau in a theoretical population, depending on population size and management, and to apply this to small populations actually selected, to predict a possible exhaustion of genetic variability. A set of subroutines describing the different steps in a selection cycle (birth, expression of phenotypic value, genetic evaluation, selection, reproduction, death) is available and the user can choose the sequence of subroutines, the characteristics of individuals submitted to each step, and also build more personal subroutines if necessary. The program is based on the generation of exact genotypes and their transmission from parents to offspring, through simulation of meiosis and pairing of gametes. Parameters concerning the genome, the initial structure of the population and its management are required. The genetic mean and variance of the population for each new cycle of selection are given as outputs. Examples of applications are given and discussed.

Effects of two insect growth regulators on ecdysteroid production in Aedes aegypti (Diptera: Culicidae).

Diflubenzuron and OMS 2017 are insect growth regulators that affect larval to adult development in Aedes aegypti (L.) by altering ecdysis. When larvae were exposed to sublethal concentrations, surviving adults express reduced reproductive potential. In mosquitoes, ecdysteroids are important in larval and adult ovarian development. We applied 30% emergence reduction concentrations (EI30) of OMS 2017 and diflubenzuron to 4th-instar Ae. aegypti to determine if changes in ecdysteroid production may explain these physiological effects. Ecdysteroid concentrations were measured in the larvae, pupae, and adults after treatment with both IGRs. After treatment with OMS 2017, the 1st peak of ecdysteroid production in larvae was totally inhibited, but after pupation, ecdysteroid concentrations were the same as in untreated controls. In diflubenzuron-treated larvae, the second peak of production was delayed and the ecdysteroid concentrations of the larvae, pupae, and adults were depressed slightly when compared with untreated controls. The production of ecdysteroids by the ovaries was not altered by sublethal larval treatment with both IGRs. Although OMS 2017 and diflubenzuron belong to the same chemical family, their mode of action apparently is different.

Effects of the insect growth regulators OMS 2017 and diflubenzuron on the reproductive potential of Aedes aegypti.

The effects of 2 benzoylphenylurea insect growth regulators, OMS 2017 and diflubenzuron, on 4th instar larvae of Aedes aegypti were investigated in the laboratory. Apart from delayed lethal action, possible effects on the reproductive potential were also studied. A baseline concentration of each compound causing 30% emergence inhibition was determined. At this concentration, OMS 2017 affected fecundity of the mosquito but diflubenzuron did not. The fertility of females that survived OMS 2017 exposure also was decreased; 23% of the eggs reached the 4th larval instar. Diflubenzuron did not cause any reduction in fertility. The basal follicle number showed great variability after both treatments as it was alternatively equal, lower, or higher than in the control.