Use of vector control to protect people from sleeping sickness in the focus of Bonon (Côte d’Ivoire)

BackgroundGambian human African trypanosomiasis (gHAT) is a neglected tropical disease caused by Trypanosoma brucei gambiense transmitted by tsetse flies (Glossina). In Côte d’Ivoire, Bonon is the most important focus of gHAT, with 325 cases diagnosed from 2000 to 2015 and efforts against gHAT have relied largely on mass screening and treatment of human cases. We assessed whether the addition of tsetse control by deploying Tiny Targets offers benefit to sole reliance on the screen-and-treat strategy.Methodology and principal findingsIn 2015, we performed a census of the human population of the Bonon focus, followed by an exhaustive entomological survey at 278 sites. After a public sensitization campaign, ~2000 Tiny Targets were deployed across an area of 130 km² in February of 2016, deployment was repeated annually in the same month of 2017 and 2018. The intervention’s impact on tsetse was evaluated using a network of 30 traps which were operated for 48 hours at three-month intervals from March 2016 to December 2018. A second comprehensive entomological survey was performed in December 2018 with traps deployed at 274 of the sites used in 2015. Sub-samples of tsetse were dissected and examined microscopically for presence of trypanosomes. The census recorded 26,697 inhabitants residing in 331 settlements. Prior to the deployment of targets, the mean catch of tsetse from the 30 monitoring traps was 12.75 tsetse/trap (5.047–32.203, 95%CI), i.e. 6.4 tsetse/trap/day. Following the deployment of Tiny Targets, mean catches ranged between 0.06 (0.016–0.260, 95%CI) and 0.55 (0.166–1.794, 95%CI) tsetse/trap, i.e. 0.03–0.28 tsetse/trap/day. During the final extensive survey performed in December 2018, 52 tsetse were caught compared to 1,909 in 2015, with 11.6% (5/43) and 23.1% (101/437) infected with Trypanosoma respectively.ConclusionsThe annual deployment of Tiny Targets in the gHAT focus of Bonon reduced the density of Glossina palpalis palpalis by >95%. Tiny Targets offer a powerful addition to current strategies towards eliminating gHAT from Côte d’Ivoire.     

Influence of physiological phenology on the seasonal pattern of ecosystem respiration in deciduous forests

Understanding the environmental and biotic drivers of respiration at the ecosystem level is a prerequisite to further improve scenarios of the global carbon cycle. In this study we investigated the relevance of physiological phenology, defined as seasonal changes in plant physiological properties, for explaining the temporal dynamics of ecosystem respiration (R_ECO) in deciduous forests. Previous studies showed that empirical R_ECO models can be substantially improved by considering the biotic dependency of R_ECO on the short‐term productivity (e.g., daily gross primary production, GPP) in addition to the well‐known environmental controls of temperature and water availability. Here, we use a model‐data integration approach to investigate the added value of physiological phenology, represented by the first temporal derivative of GPP, or alternatively of the fraction of absorbed photosynthetically active radiation, for modeling R_ECO at 19 deciduous broadleaved forests in the FLUXNET La Thuile database. The new data‐oriented semiempirical model leads to an 8% decrease in root mean square error (RMSE) and a 6% increase in the modeling efficiency (EF) of modeled R_ECO when compared to a version of the model that does not consider the physiological phenology. The reduction of the model‐observation bias occurred mainly at the monthly time scale, and in spring and summer, while a smaller reduction was observed at the annual time scale. The proposed approach did not improve the model performance at several sites, and we identified as potential causes the plant canopy heterogeneity and the use of air temperature as a driver of ecosystem respiration instead of soil temperature. However, in the majority of sites the model‐error remained unchanged regardless of the driving temperature. Overall, our results point toward the potential for improving current approaches for modeling R_ECO in deciduous forests by including the phenological cycle of the canopy.     

Population Genetics and Reproductive Strategies of African Trypanosomes: Revisiting Available Published Data

Trypanosomatidae are a dangerous family of Euglenobionta parasites that threaten the health and economy of millions of people around the world. More precisely describing the population biology and reproductive mode of such pests is not only a matter of pure science, but can also be useful for understanding parasite adaptation, as well as how parasitism, specialization (parasite specificity), and complex life cycles evolve over time. Studying this parasite’s reproductive strategies and population structure can also contribute key information to the understanding of the epidemiology of associated diseases; it can also provide clues for elaborating control programs and predicting the probability of success for control campaigns (such as vaccines and drug therapies), along with emergence or re-emergence risks. Population genetics tools, if appropriately used, can provide precise and useful information in these investigations. In this paper, we revisit recent data collected during population genetics surveys of different Trypanosoma species in sub-Saharan Africa. Reproductive modes and population structure depend not only on the taxon but also on the geographical location and data quality (absence or presence of DNA amplification failures). We conclude on issues regarding future directions of research, in particular vis-à-vis genotyping and sampling strategies, which are still relevant yet, too often, neglected issues.     

Supramolecular structure characterization of cellulose II nanowhiskers produced by acid hydrolysis of cellulose I substrates

Cellulose II nanowhiskers (CNW-II) were produced by treatment of microcrystalline cellulose with sulfuric acid by both controlling the amount of H(2)SO(4) introduced and the time of addition during the hydrolysis process. The crystalline structure was confirmed by both XRD and (13)C CP-MAS NMR spectroscopy. When observed between crossed polarizers, the cellulose II suspension displayed flow birefringence and was stable for several months. The CNW-II nanowhiskers were significantly smaller than the cellulose I nanowhiskers (CNW-I) and had a rounded shape at the tip. The CNW-II average length and height were estimated by AFM to be 153 ± 66 and 4.2 ± 1.5 nm, respectively. An average width of 6.3 ± 1.7 nm was found by TEM, suggesting a ribbon-shape morphology for these whiskers. The average dimensions of the CNW-II elementary crystallites were estimated from the XRD data, using Scherrer's equation. A tentative cross-sectional geometry consistent with both XRD and NMR data was then proposed and compared with the geometry of the CNW-I nanowhiskers.     

Breast-milk substitutes: a new old-threat for breastfeeding policy in developing countries. A case study in a traditionally high breastfeeding country

Background

Developing countries with traditionally breastfeeding are now experiencing the increasing pressure of formula milk marketing. This may endanger lives and undermine the efforts of national policies in achieving the objectives of the Millennium Development Goals. We examined the use of, and factors for use, of all available breast-milk substitutes (BMS) in a country with a traditionally high rate of breastfeeding.

Methods

Randomised multi-stage sampling surveys in 90 villages in 12/17 provinces in Laos.Participants: 1057 mothers with infants under 24 months of age.Tools: 50-query questionnaire and a poster of 22 BMS (8 canned or powdered milk; 6 non-dairy; 6 formulas; 2 non-formulas).Outcome measures included: prevalence of use and age of starting BMS in relation to socio-demographic characteristics and information sources, by univariate and multivariate analyses.

Results

Of 1057 mothers: 72.5% currently breastfed; 25.4% gave BMS (10.6% infant formula); 19.6% gave BMS before 6 months of age (of them: 83% non-dairy or cereals; mean age: 2.9 months; 95% Confidence interval: 2.6–3.2). One formula and one non-formula product accounted for 85% of BMS. BMS were considered as milk by the majority of mothers. Thai TV was the main source of information on BMS for mothers. Lao Loum mothers (the main ethnic group) living in concrete houses with good sanitary conditions, were more likely than others to use BMS before 6 months (OR: 1.79, (1.15–2.78), p<0.009). Mothers who fed their infants colostrum at birth were less likely to use BMS before 6 months of age (OR: 0.63, (0.41–0.99), p = 0.04). Unemployed mothers living in rural areas were less likely to consider BMS better than breast milk.

Conclusion

In Laos, mothers with the highest socio-economic status are showing a tendency to give up breastfeeding. Successful educational strategies and advocacy measures should be urgently developed to promote and sustain breastfeeding in developing countries.     

Antepartum Depression and Anxiety Associated with Disability in African Women: Cross-Sectional Results from the CDS Study in Ghana and C?te d'Ivoire

Background

Common mental disorders, particularly unipolar depressive disorders, rank among the top 5 with respect to the global burden of disease. As a major public health concern, antepartum depression and anxiety not only affects the individual woman, but also her offspring. Data on the prevalence of common mental disorders in pregnant women in sub-Saharan Africa are scarce. We provide results from Ghana and Côte d''Ivoire.

Methods

We subsequently recruited and screened n = 1030 women in the third trimester of their pregnancy for depressed mood, general anxiety, and perceived disability using the Patient Health Questionnaire depression module (PHQ-9), the 7-item Anxiety Scale (GAD-7), and the World Health Organisation Disability Assessment Schedule II (WHO-DAS 2.0, 12-item version). In addition to estimates of means and prevalence, a hierarchical linear regression model was calculated to determine the influence of antepartum depression and anxiety on disability.

Results

In Ghana, 26.6% of women showed substantially depressed mood. In Côte d''Ivoire, this figure was even higher (32.9%). Clear indications for a generalized anxiety disorder were observed in 11.4% and 17.4% of pregnant women, respectively. Comorbidity of both conditions was common, affecting about 7.7% of Ghanaian and 12.6% of Ivorian participants. Pregnant women in both countries reported a high degree of disability regarding everyday activity limitations and participation restrictions. Controlled for country and age, depression and anxiety accounted for 33% of variance in the disability score.

Conclusions

Antepartum depression and anxiety were highly prevalent in our sample and contributed substantially to perceived disability. These serious threats to health must be further investigated and more data are needed to comprehensively quantify the problem in sub-Saharan Africa.     

Existing competitive indices in the intercropping system of Manihot esculenta Crantz and Lagenaria siceraria (Molina) Standley

An assessment of the competitive indices in intercropping between cassava (Manihot esculenta) and bottle gourd (Lagenaria siceraria) was conducted with the aim of increasing the productivity of these crops. For this purpose, three farmers preferred landraces of cassava (yacé, blêbou and six mois) and three morphotypes of gourd (dark green and round fruit, light green and round fruit, light green and long fruit) were used to test the three intercropping ratios (gourd:cassava with 6:42, 6:24 and 6:18). Intercropping systems were assessed by land equivalent ratio (LER), area time equivalent ratio (ATER), relative crowding coefficient (K), actual yield loss (AYL), aggressivity (A) and competition ratio (CR). LER, ATER and K values were greater than 1 for gourd-cassava (6:24). These findings indicate an advantage of intercropping for exploiting the resources of the environment. Cassava clones were more competitive than gourd component.