Ecological characteristics of Simulium breeding sites in West Africa

Twenty-nine taxa of Simulium were identified amongst 527 collections of larvae and pupae from untreated rivers and streams in Liberia (362 collections in 1967–71 & 1989), Togo (125 in 1979–81), Benin (35 in1979–81) and Ghana (5 in 1980–81). Presence or absence of associations between different taxa were usedto group them into six clusters using Ward agglomerative hierarchical cluster analysis. Environmental data associated with the pre-imaginal habitats were then analysed in relation to the six clusters by oneway ANOVA. The results revealed significant effects in determining the clusters of maximum river width (all P < 0.001 unless stated otherwise), water temperature, dry bulb air temperature, relative humidity,altitude, type of water (on a range from trickle to large river), water level, slope, current, vegetation,light conditions, discharge, length of breeding area, environs, terrain, river bed type (P < 0.01), and the supports to which the insects were attached (P < 0.01). When four non-significant contributors (wet bulb temperature, river features, height of waterfall and depth) were excluded and the reduced data-set analysed by principal components analysis (PCA), the first two principal components (PCs) accounted for 87% of the variance, with geographical features dominant in PC1 and hydrological characteristics in PC2. The analyses also revealed the ecological characteristics of each taxon’s pre-imaginal habitats, which are discussed with particular reference to members of the Simulium damnosum species complex, whose breeding site distributions were further analysed by canonical correspondence analysis (CCA), a method also applied to the data on non-vector species

Onchocerciasis (river blindness) – more than a century of research and control

This review summarises more than a century of research on onchocerciasis, also known as river blindness, and its control. River blindness is an infection caused by the tissue filaria Onchocerca volvulus affecting the skin, subcutaneous tissue and eyes and leading to blindness in a minority of infected persons. The parasite is transmitted by its intermediate hosts Simulium spp. which breed in rivers. Featured are history and milestones in onchocerciasis research and control, state-of-the-art data on the parasite, its endobacteria Wolbachia, on the vectors, previous and current prevalence of the infection, its diagnostics, the interaction between the parasite and its host, immune responses and the pathology of onchocerciasis. Detailed information is documented on the time course of control programmes in the afflicted countries in Africa and the Americas, a long road from previous programmes to current successes in control of the transmission of this infectious disease. By development, adjustment and optimization of the control measures, transmission by the vector has been interrupted in foci of countries in the Americas, in Uganda, in Sudan and elsewhere, followed by onchocerciasis eliminations. The current state and future perspectives for control, elimination and eradication within the next 20–30 years are described and discussed. This review contributes to a deeper comprehension of this disease by a tissue-dwelling filaria and it will be helpful in efforts to control and eliminate other filarial infections

Lack of interaction between orlistat and oral contraceptives

Objectives: Orlistat, a potent and selective inhibitor of gastrointestinal lipases, is designed for the treatment of obesity. A double-blind, randomised, placebo-controlled, 2-way crossover study investigated the possible influence of orlistat on the ovulation-suppressing action of combination oral contraceptives (OC). Methods: After an 8-day run-in prior to the first of two consecutive menstrual cycles (Day 1 was the first day of menstruation), two groups of 10 healthy women, 20-27 years of age and on a stable regimen with OCs, received either 120 mg orlistat t.i.d. or placebo t.i.d, on Days 1-23 of the first cycle, and, separated by a placebo washout period on Days 24-28, the alternative treatment on Days 1-23 of the second cycle. In both cycles, serum luteinizing hormone (LH) was measured on Days 12-16 and progesterone on Days 12, 16, 19-23. Results: The geometric means of time-averaged concentrations (Days 12-16 for LH and Days 19-23 for progesterone) in the cycles with orlistat and placebo, respectively, and the one-sided 95% confidence region for the mean in the cycle with orlistat were 1.92, 2.03 and <2.23 IU l-1 for LH and 0.147, 0.145 and < 0.176 μg l-1 for progesterone. The one-sided 95% confidence region for the ratio (orlistat/placebo) of geometric means was < 1.06 for LH and < 1.11 for progesterone. Conclusion: During normal ovulation the peak serum concentration of LH is above 30 IU l-1 around Day 14 of the cycle, and that of progesterone exceeds 3 μg l-1 around day 21. The 95% confidence regions for the means, as well as all individual concentrations, were below these limits. It was concluded that orlistat did not influence the ovulation suppressing action of oral contraceptives. In the Netherlands, a double-blind, randomized, placebo-controlled, two-way crossover study was conducted to determine whether administration of the inhibitor of gastrointestinal lipases, Orlistat, concomitantly with combined oral contraceptives (OCs) inhibits the ovulation-suppressing action of OCs. The 20 subjects, 20-27 years old, were healthy and had a body mass index between 22 and 27 kg m-2. All subjects completed the study. Most adverse events were mild and related to the pharmacological effect of Orlistat (fatty or oily stool, flatus with discharge, or abdominal pain). The geometric means of time-averaged serum concentrations in the cycles with Orlistat and the placebo and the 1-sided 95% confidence region for the mean in the cycle with Orlistat were 0.147, 0.145, and less than 0.176 mcg l-1 for progesterone and 1.92, 2.03, and less than 2.23 IU l-1 for luteinizing hormone (LH), respectively. These figures were well below the peak concentrations during normal ovulation (3 mcg l-1 for progesterone and 30 IU l-1 for LH). The plasma concentration of Orlistat was either close to the limit of quantification (1 mcg l-1) or below this limit. These findings suggest that Orlistat had no effect on the ovulation-suppression capabilities of the OCs. Chemicals/CAS: Contraceptives, Oral, Combined; Enzyme Inhibitors; Lactones; Luteinizing Hormone, 9002-67-9; orlistat, 96829-58-2; Progesterone, 57-83-