Returns to education and experience in self-employment: Evidence from Germany

This paper compares the returns to human capital in the self-employed and wage-employed sectors of the economy. Using data from the former West German sample of the German Socioeconomic Panel survey for the 1984-1997 time period, we estimate returns to education and work experience from standard log-earnings equations for self-employed and wage-employed workers. Two key results are found. First, additional schooling has a smaller effect on earnings for the self-employed than for the wage-employed. Indeed, educational attainment has an insignificant effect on self-employment earnings. Second, prior self-employment experience receives a lower return in wage-employment than does prior wage-employment experience. These results are consistent across specifications controlling for education endogeneity and self-selection bias.

Community-based control of a neglected tropical disease: the mossy foot treatment and prevention association

Podoconiosis (endemic non-filarial elephantiasis, also known as mossy foot) is a non-communicable disease now found exclusively in the tropics, caused by the conjunction of environmental, genetic, and economic factors. Silicate particles formed by the disintegration of lava in areas of high altitude (over 1,000 m) and seasonal rainfall (over 1,000 mm per annum) penetrate the skin of barefoot subsistence farmers, and in susceptible individuals cause lymphatic blockage and subsequent elephantiasis [1]. Although an estimated one million Ethiopians (of a total population of 77 million) are afflicted with podoconiosis [2], which creates a huge economic burden in endemic areas [3], no national policy has yet been developed to control or prevent the condition, and most affected communities remain unaware of treatment options

Behavioural and insecticidal effects of organophosphate-, carbamate- and pyrethroid-treated mosquito nets against African malaria vectors.

Three insecticides - the pyrethroid deltamethrin, the carbamate carbosulfan and the organophosphate chlorpyrifos-methyl - were tested on mosquito nets in experimental huts to determine their potential for introduction as malaria control measures. Their behavioural effects and efficacy were examined in Anopheles gambiae Giles s.s. (Diptera: Culicidae) and Anopheles funestus Giles s.s. in Muheza, Tanzania, and in Anopheles arabiensis Patton and Culex quinquefasciatus Say in Moshi, Tanzania. A standardized dosage of 25 mg/m(2) plus high dosages of carbosulfan (50 mg/m(2), 100 mg/m(2) and 200 mg/m(2)) and chlorpyrifos-methyl (100 mg/m(2)) were used to compare the three types of insecticide. At 25 mg/m(2), the rank order of the insecticides for insecticide-induced mortality in wild An. gambiae and An. funestus was, respectively, carbosulfan (88%, 86%) > deltamethrin (79%, 78%) > chlorpyrifos-methyl (35%, 53%). The rank order of the insecticides for blood-feeding inhibition (reduction in the number of blood-fed mosquitoes compared with control) in wild An. gambiae and An. funestus was deltamethrin > chlorpyrifos-methyl > carbosulfan. Carbosulfan was particularly toxic to endophilic anophelines at 200 mg/m(2), killing 100% of An. gambiae and 98% of An. funestus that entered the huts. It was less effective against the more exophilic An. arabiensis (67% mortality) and carbamate-resistant Cx quinquefasciatus (36% mortality). Carbosulfan deterred anophelines from entering huts, but did not deter carbamate-resistant Cx quinquefasciatus. Deltamethrin reduced the proportion of insects engaged in blood-feeding, probably as a consequence of contact irritancy, whereas carbosulfan seemed to provide personal protection through deterred entry or perhaps a spatial repellent action. Any deployment of carbosulfan as an individual treatment on nets should be carried out on a large scale to reduce the risk of diverting mosquitoes to unprotected individuals. Chlorpyrifos-methyl was inferior to deltamethrin in terms of mortality and blood-feeding inhibition and would be better deployed on a net in combination with a pyrethroid to control insecticide-resistant mosquitoes

Mutations in dhfr in Plasmodium falciparum infections selected by chlorproguanil-dapsone treatment.

Treatment with the novel antifolate drug combination chlorproguanil-dapsone effectively cleared asymptomatic Plasmodium falciparum infections in 246 (93.5%) of 263 children in the Usambara Mountains of Tanzania during the course of a 2-week follow-up. Samples from 71 recurrent infections, collected over a 9-week follow-up, showed selection for parasites with the triple mutant Ile(51)-Arg(59)-Asn(108) in dihydrofolate reductase. There was no selection for mutations in dihydropteroate synthetase, the target enzyme of dapsone. Search for complete identity in the highly polymorphic genes coding for merozoite surface proteins 1 and 2 in parasite samples collected before and after treatment indicated that the majority of recurrent parasitemias were new infections. These observations on selection in Tanzania and the lack of selection reported from a less endemic area suggest that the active metabolite of chlorproguanil, which has a short half-life in the blood, may persist in the liver, where it exerts selective pressure on growing preerythrocytic stages

Emerging priorities for HIV service delivery

Nathan Ford and co-authors discuss global priorities in the provision of HIV prevention and treatment services

Screening mosquito house entry points as a potential method for integrated control of endophagic filariasis, arbovirus and malaria vectors.

BACKGROUND: Partial mosquito-proofing of houses with screens and ceilings has the potential to reduce indoor densities of malaria mosquitoes. We wish to measure whether it will also reduce indoor densities of vectors of neglected tropical diseases. METHODOLOGY: The main house entry points preferred by anopheline and culicine vectors were determined through controlled experiments using specially designed experimental huts and village houses in Lupiro village, southern Tanzania. The benefit of screening different entry points (eaves, windows and doors) using PVC-coated fibre glass netting material in terms of reduced indoor densities of mosquitoes was evaluated compared to the control. FINDINGS: 23,027 mosquitoes were caught with CDC light traps; 77.9% (17,929) were Anopheles gambiae sensu lato, of which 66.2% were An. arabiensis and 33.8% An. gambiae sensu stricto. The remainder comprised 0.2% (50) An. funestus, 10.2% (2359) Culex spp. and 11.6% (2664) Mansonia spp. Screening eaves reduced densities of Anopheles gambiae s. l. (Relative ratio (RR) = 0.91; 95% CI = 0.84, 0.98; P = 0.01); Mansonia africana (RR = 0.43; 95% CI = 0.26, 0.76; P<0.001) and Mansonia uniformis (RR = 0.37; 95% CI = 0.25, 0.56; P<0.001) but not Culex quinquefasciatus, Cx. univittatus or Cx. theileri. Numbers of these species were reduced by screening windows and doors but this was not significant. SIGNIFICANCE: This study confirms that across Africa, screening eaves protects households against important mosquito vectors of filariasis, Rift Valley Fever and O'Nyong nyong as well as malaria. While full house screening is required to exclude Culex species mosquitoes, screening of eaves alone or fitting ceilings has considerable potential for integrated control of other vectors of filariasis, arbovirus and malaria

Sustaining control of Schistosomiasis mansoni in western Côte d'Ivoire : results from a SCORE study, one year after initial praziquantel administration

The Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) has launched several large-scale trials to determine the best strategies for gaining and sustaining control of schistosomiasis and transitioning toward elimination. In Côte d'Ivoire, a 5-year cluster-randomized trial is being implemented in 75 schools to sustain the control of schistosomiasis mansoni. We report Schistosoma mansoni infection levels in children one year after the initial school-based treatment (SBT) with praziquantel and compare with baseline results to determine the effect of the intervention.; The baseline cross-sectional survey was conducted in late 2011/early 2012 and the first follow-up in May 2013. Three consecutive stool samples were collected from 9- to 12-year-old children in 75 schools at baseline and 50 schools at follow-up. Stool samples were subjected to duplicate Kato-Katz thick smears. Directly observed treatment (DOT) coverage of the SBT was assessed and the prevalence and intensity of S. mansoni infection compared between baseline and follow-up.; The S. mansoni prevalence in the 75 schools surveyed at baseline was 22.1% (95% confidence interval (CI): 19.5-24.4%). The DOT coverage was 84.2%. In the 50 schools surveyed at baseline and one year after treatment, the overall prevalence of S. mansoni infection decreased significantly from 19.7% (95% CI: 18.5-20.8%) to 12.8% (95% CI: 11.9-13.8%), while the arithmetic mean S. mansoni eggs per gram of stool (EPG) among infected children slightly increased from 92.2 EPG (95% CI: 79.2-105.3 EPG) to 109.3 EPG (95% CI: 82.7-135.9 EPG). In two of the 50 schools, the prevalence increased significantly, despite a DOT coverage of &gt;75%.; One year after the initial SBT, the S. mansoni prevalence had decreased. Despite this positive trend, an increase was observed in some schools. Moreover, the infection intensity among S. mansoni-infected children was slightly higher at the 1-year follow-up compared to the baseline situation. Our results emphasize the heterogeneity of transmission dynamics and provide a benchmark for the future yearly follow-up surveys of this multi-year SCORE intervention study

Consistently high estimates for the proportion of human exposure to malaria vector populations occurring indoors in rural Africa.

BACKGROUND: Insecticide-treated nets (ITNs) and indoor residual spraying (IRS) are highly effective tools for controlling malaria transmission in Africa because the most important vectors, from the Anopheles gambiae complex and the A. funestus group, usually prefer biting humans indoors at night. METHODS: Matched surveys of mosquito and human behaviour from six rural sites in Burkina Faso, Tanzania, Zambia, and Kenya, with ITN use ranging from 0.2% to 82.5%, were used to calculate the proportion of human exposure to An. gambiae sensu lato and An. funestus s.l. that occurs indoors (πi), as an indicator of the upper limit of personal protection that indoor vector control measures can provide. This quantity was also estimated through use of a simplified binary analysis (π(i)(B)) so that the proportions of mosquitoes caught indoors (Pi), and between the first and last hours at which most people are indoors (Pfl) could also be calculated as underlying indicators of feeding by mosquitoes indoors or at night, respectively. RESULTS: The vast majority of human exposure to Anopheles bites occurred indoors (π(i)(B)= 0.79-1.00). Neither An. gambiae s.l. nor An. funestus s.l. strongly preferred feeding indoors (P(i) = 0.40-0.63 and 0.22-0.69, respectively), but they overwhelmingly preferred feeding at times when most humans were indoors (P(fl) = 0.78-1.00 and 0.86-1.00, respectively). CONCLUSIONS: These quantitative summaries of behavioural interactions between humans and mosquitoes constitute a remarkably consistent benchmark with which future observations of vector behaviour can be compared. Longitudinal monitoring of these quantities is vital to evaluate the effectiveness of ITNs and IRS and the need for complementary measures that target vectors outdoors

Epidemiology and individual, household and geographical risk factors of podoconiosis in ethiopia: results from the first nationwide mapping

Although podoconiosis is one of the major causes of tropical lymphoedema and is endemic in Ethiopia its epidemiology and risk factors are poorly understood. Individual-level data for 129,959 individuals from 1,315 communities in 659 woreda (districts) were collected for a nationwide integrated survey of lymphatic filariasis and podoconiosis. Blood samples were tested for circulating Wuchereria bancrofti antigen using immunochromatographic card tests. A clinical algorithm was used to reach a diagnosis of podoconiosis by excluding other potential causes of lymphoedema of the lower limb. Bayesian multilevel models were used to identify individual and environmental risk factors. Overall, 8,110 of 129,959 (6.2%, 95% confidence interval [CI] 6.1-6.4%) surveyed individuals were identified with lymphoedema of the lower limb, of whom 5,253 (4.0%, 95% CI 3.9-4.1%) were confirmed to be podoconiosis cases. In multivariable analysis, being female, older, unmarried, washing the feet less frequently than daily, and being semiskilled or unemployed were significantly associated with increased risk of podoconiosis. Attending formal education and living in a house with a covered floor were associated with decreased risk of podoconiosis. Podoconiosis exhibits marked geographical variation across Ethiopia, with variation in risk associated with variation in rainfall, enhanced vegetation index, and altitude