The impact of climate change on mosquito-borne diseases in Africa.

Despite being one of the continents with the least greenhouse gas emissions, no continent is being struck as severely by climate change (CC) as Africa. Mosquito-borne diseases (MBD) cause major human diseases in this continent. Current knowledge suggests that MBD range could expand dramatically in response to CC. This study aimed at assessing the relationship between CC and MBD in Africa. Methods For this purpose, a systematic peer review was carried out, considering all articles indexed in PubMed, Scopus, Embase and CENTRAL. Search terms referring to MBD, CC and environmental factors were screened in title, abstract and keywords.Results A total of twenty-nine studies were included, most of them on malaria (61%), being Anopheles spp. (61%) the most commonly analyzed vector, mainly in Eastern Africa (48%). Seventy-nine percent of these studies were based on predictive models. Seventy-two percent of the reviewed studies considered that CC impacts on MBD epidemiology. MBD prevalence will increase according to 69% of the studies while 17% predicted a decrease. MBD expansion throughout the continent was also predicted. Most studies showed a positive relationship between observed or predicted results and CC. However, there was a great heterogeneity in methodologies and a tendency to reductionism, not integrating other variables that interact with both the environment and MBD. In addition, most results have not yet been tested. A global health approach is desirable in this kind of research. Nevertheless, we cannot wait for science to approve something that needs to be addressed now to avoid greater effects in the future.

The economic and nutrition transition in Equatorial Guinea coincided with a double burden of over- and under nutrition.

We assess trends in children's nutritional status in Equatorial Guinea, a country in socioeconomic transition. Nationally representative samples were conducted in 1997, at the start of the economic take off, and again in 2004. Children aged 0-60 months were included in the surveys (N=436, 552). Both surveys included a sociodemographic, dietary and health questionnaire, and anthropometric measurements from which height-for-age (HAZ); weight-for-age (WAZ) and weight-for-height (WHZ) Z-scores were calculated. Between 1997 and 2004, the prevalence of child overweight for all children increased from 21.8% to 31.7%, especially in urban areas (from 18.2% to 29.4%, p=0.01). Stunting prevalence among children >or=2 years old decreased (from 57.9% to 45.3%, p<0.02), but for all age groups remained very high (34.7% overall, 46.5% rural and 28.5% urban in 2004). The economic take off in Equatorial Guinea appeared to coincide with substantial increases in the prevalence of child overweight whereas the prevalence of stunting decreased even if it remained high. The results suggest that the country is undergoing a nutrition transition and acquiring the concomitant double burden of under and over nutrition.

Nutritional and socio-economic factors associated with Plasmodium falciparum infection in children from Equatorial Guinea: results from a nationally representative survey.

BACKGROUND: Malaria has traditionally been a major endemic disease in Equatorial Guinea. Although parasitaemia prevalence on the insular region has been substantially reduced by vector control in the past few years, the prevalence in the mainland remains over 50% in children younger than five years. The aim of this study is to investigate the risk factors for parasitaemia and treatment seeking behaviour for febrile illness at country level, in order to provide evidence that will reinforce the EG National Malaria Control Programme. METHODS: The study was a cross-sectional survey of children 0 to 5 years old, using a multistaged, stratified, cluster-selected sample at the national level. It included a socio-demographic, health and dietary questionnaires, anthropometric measurements, and thick and thin blood smears to determine the Plasmodium infection. A multivariate logistic regression model was used to determine risk factors for parasitaemia, taking into account the cluster design. RESULTS: The overall prevalence of parasitemia was 50.9%; it was higher in rural (58.8%) compared to urban areas (44.0%, p = 0.06). Age was positively associated with parasitemia (p < 0.0001). In rural areas, risk factors included longer distance to health facilities (p = 0.01) and a low proportion of households with access to protected water in the community (p = 0.02). Having had an episode of cough in the 15 days prior to the survey was inversely related to parasitemia (p = 0.04). In urban areas, the risk factors were stunting (p = 0.005), not having taken colostrum (p = 0.01), and that someone in the household slept under a bed net (p = 0.002); maternal antimalarial medication intake during pregnancy (p = 0.003) and the household socio-economic status (p = 0.0002) were negatively associated with parasitemia. Only 55% of children with fever were taken outside their homes for care, and treatment seeking behaviour differed substantially between rural and urban populations. CONCLUSION: Results suggest that a national programme to fight malaria in Equatorial Guinea should take into account the differences between rural and urban communities in relation to risk factors for parasitaemia and treatment seeking behaviour, integrate nutrition programmes, incorporate campaigns on the importance of early treatment, and target appropriately for bed nets to reach the under-fives.

Efficacy of Artesunate + Sulphadoxine-Pyrimethamine (AS + SP) and Amodiaquine + Sulphadoxine-Pyrimethamine (AQ + SP) for Uncomplicated falciparum Malaria in Equatorial Guinea (Central Africa).

Objectives. The objectives of the study were (i) to evaluate the efficacy of combination drugs, such as artesunate + sulphadoxine-pyrimethamine (AS + SP) and amodiaquine + sulphadoxine-pyripethamine (AQ + SP) in treatment of uncomplicated falciparum malaria (ii) to differentiate recrudescence from reinfection by analysing msp-1 and msp-2 genes of Plasmodium falciparum in treatment failure cases. Methods. We carried out an in vivo study in the year 2005 in 206 children between 6 to 59 months age groups. Of the 206, 120 received AQ + SP, and 86 received AS + SP. A clinical and parasitological followup during 14 days was undertaken. Finger-prick blood sample from each patient was taken on Whatman filter paper (no. 3) on days 0, 7, 14 and also the day when the parasite and symptoms reappeared for PCR analysis. Results. Late treatment failure was observed in 3.5% (4/114) with AQ + SP, and 2.5% (2/79) with AS + SP. The success rate was 96.5% with AQ + SP and 97.5% with AS + SP. No deaths and severe reactions were recorded. Out of the 6 treatment failure cases, one was reinfection as observed by PCR analysis of msp-1 and msp-2 genes on day 14. Discussion. Both the combinations found to be efficacious and safe and could be used as a first-line treatment for uncomplicated falciparum malaria in Equatorial Guinea.

Nutritional status and its correlates in Equatorial Guinean preschool children: results from a nationally representative survey.

BACKGROUND: In Equatorial Guinea, as a result of the recent growth of the oil industry, there is an opportunity to address important public health problems through public and private initiatives. To propose effective nutrition and public health strategies, it is important first to have reliable information on the nutritional status of the population and the underlying factors affecting it. OBJECTIVE: To assess the nutritional status and the prevalence of anemia among Equatoguinean children in a nationally representative sample and to identify the risk factors associated with the nutritional problems detected. METHODS: The study was a cross-sectional survey using a multistaged, stratified, cluster-selected sample. The survey included a sociodemographic, health, and dietary questionnaire and measurement of hematocrit and anthropometric features, from which nutritional indicators based on the National Center for Health Statistics (NCHS) reference and the World Health Organization (WHO) standards were calculated. Logistic regression models were used for the multivariate analysis. A total of 552 children aged 0 to 60 months were surveyed. RESULTS: The overall prevalence of stunting (< -2 height-for-age z-scores [HAZ]) was 29.7% based on the NCHS reference and 35.2% based on WHO standards; the risk factors associated with stunting were age (p < .0001), low socioeconomic status (p = .01), and fishing by a member of the household (p = .003) The prevalence of mild anemia (hemoglobin < 110 g/L) was 69.3%, and that of moderate or severe anemia (hemoglobin < 80 g/L) was 8.3%. The only significant risk factor associated with moderate to severe anemia was low household socioeducational level (p = .01). CONCLUSIONS: Stunting and anemia are public health problems in Equatorial Guinea. Integrated strategies, including fighting poverty and improving maternal education, should be undertaken.

Spatial and temporal variability of the Glossina palpalis palpalis population in the Mbini focus (Equatorial Guinea).

BACKGROUND: Human African Trypanosomiasis is a vector-borne parasitic disease. The geographical distribution of the disease is linked to the spatial distribution of the tsetse fly. As part of a control campaign using traps, the spatial and temporal variability is analysed of the glossina populations present in the Mbini sleeping sickness foci (Equatorial Guinea). RESULTS: A significant drop in the annual mean of the G. p. palpalis apparent density was noted from 2004 to 2005, although seasonal differences were not observed. The apparent density (AD) of G. p. palpalis varies significantly from one biotope to another. The fish dryers turned out to be zones with the greatest vector density, although the AD of G. p. palpalis fell significantly in all locations from 2004 to 2005. CONCLUSION: Despite the tsetse fly density being relatively low in fish dryers and jetties, the population working in those zones would be more exposed to infection. The mono-pyramidal traps in the Mbini focus have been proven to be a useful tool to control G. p. palpalis, even though the activity on the banks of the River Wele needs to be intensified. The application of spatial analysis techniques and geographical information systems are very useful tools to discriminate zones with high and low apparent density of G. p. palpalis, probably associated with different potential risk of sleeping sickness transmission.

Predicted distribution and movement of Glossina palpalis palpalis (Diptera: Glossinidae) in the wet and dry seasons in the Kogo trypanosomiasis focus (Equatorial Guinea).

The aim of this study was to predict the distribution and movement of populations of the tsetse fly, Glossina palpalis palpalis (Diptera: Glossinidae), in the wet and dry seasons and to analyze the impact of the use of mono-pyramidal traps on fly populations in the Kogo focus in 2004 and 2005. Three Glossina species are present in Kogo: Glossina palpalis palpalis, major HAT vector in West-Central Africa, Glossina caliginea, and Glossina tabaniformis. The apparent density (AD) of G. p. palpalis clearly fell from 1.23 tsetse/trap/day in July 2004 to 0.27 in December 2005. A significant reduction in the mean AD for this species was noted between seasons and years. The diversity of Glossina species was relatively low at all the sampling points; G. p. palpalis clearly predominated over the other species and significantly dropped as a consequence of control activities. The predictive models generated for the seasonal AD showed notable differences not only in the density but in the distribution of the G. p. palpalis population between the rainy and dry season. The mono-pyramidal traps have proven to be an effective instrument for reducing the density of the tsetse fly populations, although given that the Kogo trypanosomiasis focus extends from the southern Equatorial Guinea to northern Gabon, interventions need to be planned on a larger scale, involving both countries, to guarantee the long-term success of control.

Impact of different strategies to control Plasmodium infection and anaemia on the island of Bioko (Equatorial Guinea).

BACKGROUND: On the island of Bioko (Equatorial Guinea), insecticide-treated nets (ITNs) have been the main tool used to control malaria over the last 13 years. In 2004, started an indoor residual spraying (IRS) campaign to control malaria. The purpose of this study is to asses the impact of the two control strategies on the island of Bioko (Equatorial Guinea), with regards to Plasmodium infection and anaemia in the children under five years of age. METHODS: Two transversal studies, the first one prior to the start of the IRS campaign and the second one year later. Sampling was carried out by stratified clusters. Malaria infection was measured by means of thick and thin film, and the packed cell volume (PCV) percentage. Data related to ITN use and information regarding IRS were collected. The Pearson's chi-square and logistic regression statistical tests were used to calculate odds ratios (OR). RESULTS: In the first survey, 168 children were sampled and 433 children in the second one. The prevalence of infection was 40% in 2004, and significantly lower at 21.7% in 2005. PCV was 41% and 39%, respectively. 58% of the children surveyed in 2004 and 44.3% in 2005 had slept under an ITN. 78% of the dwellings studied in 2005 had been sprayed. In the 2005 survey, sleeping without a mosquito net meant a risk of infection 3 times greater than sleeping protected with a net hanged correctly and with no holes (p < 0.05). CONCLUSION: IRS and ITNs have proven to be effective control strategies on the island of Bioko. The choice of one or other strategy is, above all, a question of operational feasibility and availability of local resources.

Surveillance of in vivo resistance of Plasmodium falciparum to antimalarial drugs from 1992 to 1999 in Malabo (Equatorial Guinea).

From 1992-1999, we have assessed the therapeutic efficacy of three malaria treatment regimens (chloroquine 25 mg/kg over three days, pyrimethamine/sulfadoxine 1.25/25 mg/kg in one dose, and quinine 25-30 mg/kg daily in three oral doses over a four-, five-, or seven-day period) in 1,189 children under age 10 at Malabo Regional Hospital in Equatorial Guinea. Of those children, 958 were followed up clinically and parasitologically for 14 days. With chloroquine, the failure rate varied from 55% in 1996 to 40% in 1999; the early treatment failure rate increased progressively over the years, from 6% in 1992 to 30% in 1999. With pyrimethamine/sulfadoxine, the failure rate varied from 0% in 1996 to 16% in 1995. The short quinine treatment regimens used in 1992 and 1993 (4 and 5 days, respectively) resulted in significantly higher failure rates (19% and 22%, respectively) than the 7d regimen (3-5.5%). We conclude that: a) failure rates for chloroquine are in the change period (> 25%), and urgent action is needed; b) pyrimethamine/ sulfadoxine failure rates are in the alert period (6-15%), and surveillance must be continued; and c) quinine failure rates are in the grace period (< 6%), so quinine can be recommended.