Onchocerciasis transmission in Ghana: Persistence under different control strategies and the role of the simuliid vectors

Background: The World Health Organization (WHO) aims at eliminating onchocerciasis by 2020 in selected African countries. Current control focuses on community-directed treatment with ivermectin (CDTI). In Ghana, persistent transmission has been reported despite long-term control. We present spatial and temporal patterns of onchocerciasis transmission in relation to ivermectin treatment history. Methodology/Principal Findings: Host-seeking and ovipositing blackflies were collected from seven villages in four regions of Ghana with 3–24 years of CDTI at the time of sampling. A total of 16,443 flies was analysed for infection; 5,812 (35.3%) were dissected for parity (26.9% parous). Heads and thoraces of 12,196 flies were dissected for Onchocerca spp. and DNA from 11,122 abdomens was amplified using Onchocerca primers. A total of 463 larvae (0.03 larvae/fly) from 97 (0.6%) infected and 62 (0.4%) infective flies was recorded; 258 abdomens (2.3%) were positive for Onchocerca DNA. Infections (all were O. volvulus) were more likely to be detected in ovipositing flies. Transmission occurred, mostly in the wet season, at Gyankobaa and Bosomase, with transmission potentials of, respectively, 86 and 422 L3/person/month after 3 and 6 years of CDTI. The numbers of L3/1,000 parous flies at these villages were over 100times the WHO threshold of one L3/1,000 for transmission control. Vector species influenced transmission parameters. At Asubende, the number of L3/1,000 ovipositing flies (1.4, 95% CI = 0–4) also just exceeded the threshold despite extensive vector control and 24 years of ivermectin distribution, but there were no infective larvae in host-seeking flies. Conclusions/Significance: Despite repeated ivermectin treatment, evidence of O. volvulus transmission was documented in all seven villages and above the WHO threshold in two. Vector species influences transmission through biting and parous rates and vector competence, and should be included in transmission models. Oviposition traps could augment vector collector methods for monitoring and surveillance

Prevalência do aleitamento materno no Distrito Federal, Brasil Prevalence of breast-feeding in Brasilia, Brazil

O artigo relata os resultados de um inquérito transversal, de base populacional, realizado em Dia Nacional de Vacinação. Um grupo de 3.305 mães, com filhos na faixa etária de 0 a 180 dias, selecionado por amostragem sistemática, foi entrevistado com questionário pré-testado. A prevalência do aleitamento materno exclusivo, na faixa etária de 0-15 dias, foi de 62% (intervalo de confiança de 95%: 58,5-65,3) e de 12,8% (11,0-14,7), na faixa etária de 151-180 dias. A duração mediana do aleitamento materno exclusivo correspondeu a 39,4 dias. O aleitamento predominante manteve-se constante ao longo dos intervalos etários, com uma prevalência média de 33,1% (31,4-34,7), enquanto o parcial variou de 4,5% (3,1-6,4) a 28,4% (25,8-31,0), nas idades mencionadas. Para o aleitamento materno (todas as modalidades), a prevalência foi de 96,8% (95,8-97,7) e 70,9% (67,7-73,9), respectivamente. Em conclusão, a prevalência do aleitamento materno no Distrito Federal é elevada, mas é curto o período em que as crianças são amamentadas exclusivamente ao seio.<br>This article presents the findings of a population-based cross-sectional survey carried out during a mass immunization campaign. A group of 3,305 mothers whose babies were 0 to 180 days old was selected by systematic sampling and interviewed with a pretested questionnaire. The prevalence of exclusive breast-feeding among 0-15 day-old children was 62% (IC 95%: 58.5-65.3) and 12.8% (11.0-14.7), among 151-180 day-old children. The average duration of exclusive breast-feeding was 39.4 days. The prevalence of predominant breast-feeding was invariable along the age intervals showing a mean of 33.1% (31.4-34.7). The prevalence of partial breast-feeding among 0-15 day-old children was 4.5% (3.1-6.4) and 28.4% (25.8-31.0) for the mentioned age groups. For maternal breast-feeding, the overall prevalence varied from 96.8% (95.8-97.7) to 70.9% (67.7-73.9). In conclusion, although the overall prevalence of breast-feeding in Brasilia is relatively high, the period that children are exclusively breast-fed is short

Seston capture by Hydropsyche siltalai and the accuracy of capture efficiency estimates

1. Suspension feeding by caseless caddisfly larvae (Trichoptera) constitutes a major pathway for energy flow, and strongly influences productivity, in streams and rivers. 2. Consideration of the impact of these animals on lotic ecosystems has been strongly influenced by a single study investigating the efficiency of particle capture of nets built by one species of hydropsychid caddisfly. 3. Using water sampling techniques at appropriate spatial scales, and taking greater consideration of local hydrodynamics than previously, we examined the size-frequency distribution of particles captured by the nets of Hydropsyche siltalai. Our results confirm that capture nets are selective in terms of particle size, and in addition suggest that this selectivity is for particles likely to provide the most energy. 4. By incorporating estimates of flow diversion around the nets of caseless caddisfly larvae, we show that capture efficiency (CE) is considerably higher than previously estimated, and conclude that more consideration of local hydrodynamics is needed to evaluate the efficiency of particle capture. 5. We use our results to postulate a mechanistic explanation for a recent example of interspecific facilitation, whereby a reduction of near-bed velocities seen in single species monocultures leads to increased capture rates and local depletion of seston within the region of reduced velocity

Trente ans de lutte contre l’onchocercose en Afrique de l’Ouest. Traitements larvicides et protection de l’environnement

La lutte contre l'onchocercose, ou cécité des rivières, une maladie parasitaire endémique, fut entreprise en Afrique de l'Ouest dans une perspective do développement durable. Tous les moyens technologiques disponibles ont de ce fait été mobilisés pour le contrôle du vecteur, une simulie, puis du parasite responsables de cette maladie, par le Programme de Lutte contre l’Onchocercose en Afrique de l'Ouest (OCP). La lutte antivectorielle consistant en épandages d’insecticides chimiques sur les sites de développement de la simulie dans les rivières, il est apparu indispensable d’assurer la sauvegarde de l’environnement aquatique qui fournit aux communautés riveraines eau et ressources biologiques. Les technologies les plus modernes ont été mises en œuvre dès leur mise au point, pour combattre la maladie, contribuant ainsi à la protection de ce milieu. Le programme de surveillance écologique des rivières traitées par des larvicides anti-simulies a été mis en place dès le lancement d’OCP. et assuré par des spécialistes de I' hydrobiologie des pays africains participants du Programme, sous la supervision d’un groupe international d’experts indépendants, le Groupe Écologique. OCP est incontestablement un succès aussi bien pour ce qui est du contrôle de la maladie que de la protection de l'environnement. Il est l'exemple unique au monde d’un programme de santé publique de longue durée qui depuis son origine a mis en œuvre tout ce qui était possible pour harmoniser les enjeux de l’amélioration de la santé et ceux de la protection de l’environnement. Il s'est achevé avec la satisfaction de laisser aux générations montantes un environnement non dégradé et des vallées libérées de l’onchocercose, qui permettront d’accroître la productivité agricole des pays africains.The control of onchocerciasis, or river blindness, an endemic parasitic disease, was implemented in West Africa in the perspective of sustainable development AH the available technological means to fight this disease, by way of the control of its blackfly vector, then its parasite, were therefore implemented by the Onchocerciasis Control Programme in West Africa (OCP). Vector control being achieved through applications of chemicals on its river breeding sites, it was necessary, at the same time, to fight for the preservation of the aquatic environment, which supplies the communities that live along the rivers with water and biological resources. This was the spirit in which the OCP was set up and implemented, and the most modem technologies were used as they become available to fight the disease, thus facilitating the preservation of the aquatic environment. This Programme has indisputably been a success as regards the control of the disease as also from the point of view of the preservation of the environment The aquatic monitoring programme of the rivers under treatment with anti-simulid larvicides was set up right from the very beginning, and performed by national experts of the Participating Countries of the Programme, under the aegis of a group of international independent experts, the Ecological Croup The Onchocerciasis Control Programme in West Africa is an unique example in the world of a long-term public health programme which has made every effort possible from its inception to adequately combine health and environment issues. It ended with the satisfaction of bequeathing to the coming generations a non degraded environment and valleys freed from onchocerciasis which would increase the agricultural productivity of the countries

Suspension and Filter Feeding In Aquatic Insects

Aquatic insect feeding occurs at the nexus of habitat, food source and size, and behavior and relies largely on the complexities of mouthpart morphology. This intersection has important consequences for tropic interactions, nutrient processing, and ecosystem function. In aquatic habitats, immature insects feed in a variety of ways; however, consumption of small suspended particles (seston) in the water column is a common mode for representatives of several insect groups. Ingestion of seston can occur via active or passive removal and broadly encompasses filter and suspension feeding. In this chapter, we explore the ways in which various aquatic insects acquire food particles. We focus on food sources and particle sizes, feeding behavior, morphology of mouthparts, and trophic importance. The major groups explored include Ephemeroptera (mayflies), Diptera (true flies), and Trichoptera (caddisflies), each of which have evolved unique strategies for obtaining particles from the water column. Members of this feeding group are critical as food sources for aquatic and terrestrial organisms, they play large roles in nutrient cycling, and some are vectors of important human and animal diseases