Browsing by Author "Marc Coosemans"

Now showing 1 - 6 of 6

Effect of untreated bed nets on blood-fed Phlebotomus argentipes in kala-azar endemic foci in Nepal and India
(Fundacao Oswaldo Cruz, 2009) Albert Picado; Vijay Kumar; Murari Das; Ian Burniston; Lalita Roy; Rijal Suman; Diwakar Dinesh; Marc Coosemans; Shyam Sundar; Kesari Shreekant; Marleen Boelaert; Clive Davies; Mary Cameron
Observational studies in the Indian subcontinent have shown that untreated nets may be protective against visceral leishmaniasis (VL). In this study, we evaluated the effect of untreated nets on the blood feeding rates of Phlebotomus argentipes as well as the human blood index (HBI) in VL endemic villages in India and Nepal. The study had a "before and after intervention" design in 58 households in six clusters. The use of untreated nets reduced the blood feeding rate by 85% (95% CI 76.5-91.1%) and the HBI by 42.2% (95% CI 11.1-62.5%). These results provide circumstantial evidence that untreated nets may provide some degree of personal protection against sand fly bites.
Effect of village-wide use of long-lasting insecticidal nets on visceral Leishmaniasis vectors in India and Nepal: A cluster randomized trial
(2010) Albert Picado; Murari L. Das; Vijay Kumar; Shreekant Kesari; Diwakar S. Dinesh; Lalita Roy; Suman Rijal; Pradeep Das; Mark Rowland; Shyam Sundar; Marc Coosemans; Marleen Boelaert; Clive R. Davies
Background: Visceral leishmaniasis (VL) control in the Indian subcontinent is currently based on case detection and treatment, and on vector control using indoor residual spraying (IRS). The use of long-lasting insecticidal nets (LN) has been postulated as an alternative or complement to IRS. Here we tested the impact of comprehensive distribution of LN on the density of Phlebotomus argentipes in VL-endemic villages. Methods: A cluster-randomized controlled trial with household P. argentipes density as outcome was designed. Twelve clusters from an ongoing LN clinical trial - three intervention and three control clusters in both India and Nepal - were selected on the basis of accessibility and VL incidence. Ten houses per cluster selected on the basis of high pre-intervention P. argentipes density were monitored monthly for 12 months after distribution of LN using CDC light traps (LT) and mouth aspiration methods. Ten cattle sheds per cluster were also monitored by aspiration. Findings:A random effect linear regression model showed that the cluster-wide distribution of LNs significantly reduced the P. argentipes density/house by 24.9% (95% CI 1.80%-42.5%) as measured by means of LTs. Interpretation: The ongoing clinical trial, designed to measure the impact of LNs on VL incidence, will confirm whether LNs should be adopted as a control strategy in the regional VL elimination programs. The entomological evidence described here provides some evidence that LNs could be usefully deployed as part of the VL control program. Trial registration: ClinicalTrials.gov CT-2005-015374. © 2010 Picado et al.
Insecticide susceptibility of Phlebotomus argentipes in visceral leishmaniasis endemic districts in India and Nepal
(2010) Diwakar Singh Dinesh; Murari Lal Das; Albert Picado; Lalita Roy; Suman Rijal; Shri Prakash Singh; Pradeep Das; Marleen Boelaert; Marc Coosemans
Objectives: To investigate the DDT and deltamethrin susceptibility of Phlebotomus argentipes, the vector of Leishmania donovani, responsible for visceral leishmaniasis (VL), in two countries (India and Nepal) with different histories of insecticide exposure. Methods: Standard WHO testing procedures were applied using 4% DDT and 0.05% deltamethrin impregnated papers. The effect of the physiological status (fed and unfed) of females on the outcome of the bioassays was assessed and the optimal time of exposure for deltamethrin was evaluated on a colony population. Field populations from both countries were tested. Results: Fed and unfed females responded in a similar way. For exposure time on field samples 60 min was adopted for both DDT and deltamethrin. In Bihar, knockdown and mortality with DDT was respectively 20 and 43%. In Nepal almost all sand flies were killed, except at the border with Bihar (mortality 62%). With 0.05% deltamethrin, between 96 and 100% of the sand flies were killed in both regions. Conclusions: Based on literature and present data 4% DDT and 0.05% deltamethrin seem to be acceptable discriminating concentrations to separate resistant from susceptible populations. Resistance to DDT was confirmed in Bihar and in a border village of Nepal, but the sand flies were still susceptible in villages more inside Nepal where only synthetic pyrethroids are used for indoor spraying. The low effectiveness of indoor spraying with DDT in Bihar to control VL can be partially explained by this resistance hence other classes of insecticides should be tested. In both countries P. argentipes sand flies were susceptible to deltamethrin. © 2010 Dinesh et al.
Long-lasting Insecticidal Nets to Prevent Visceral Leishmaniasis in the Indian Subcontinent; Methodological Lessons Learned from a Cluster Randomised Controlled Trial
(Public Library of Science, 2015) Albert Picado; Bart Ostyn; Suman Rijal; Shyam Sundar; Shri Prakash Singh; François Chappuis; Murari Lal Das; Basudha Khanal; Kamlesh Gidwani; Epco Hasker; Jean Claude Dujardin; Veerle Vanlerberghe; Joris Menten; Marc Coosemans; Marleen Boelaert
[No abstract available]
Phlebotomus argentipes seasonal patterns in India and Nepal
(2010) Albert Picado; Murari Lal Das; Vijay Kumar; Diwakar S. Dinesh; Suman Rijal; Shri P. Singh; Pradeep Das; Marc Coosemans; Marleen Boelaert; Clive Davies
The current control of Phebotomus argentipes (Annandale and Brunetti), the vector of Leishmania donovani (Laveran and Mesnil), on the Indian subcontinent is base on indoor residual spraying. The efficacy of this method depends, among other factors, on the timing and number of spraying rounds, which depend on the P. argentipes seasonality. To describe P. argentipes' seasonal patterns, six visceral leishmaniasis (VL) endemic villages, three in Muzaffarpur and three in Sunsari districts in India and Nepal, respectively, were selected based on accessibility and VL incidence. Ten houses per cluster with the highest P. argentipes density were monitored monthly for 1516 mo using Center for Disease Control and Prevention light traps. Minimum and maximum temperature and rainfall data for the months January 2006 through December 2007 were collected from the nearest available weather stations. Backwards stepwise regression was used to generate the minimal adequate model for explaining the monthly variation in P. argentipes populations. The seasonality of P. argentipes is similar in India and Nepal, with two annual density peaks around May and October. Monthly P. argentipes density is positively associated with temperature and negatively associated with rainfall in both study sites. The multivariate climate model explained 57% of the monthly vectorial abundance. Vector control programs against P. argentipes (i.e., indoor residual spraying) should take into account the seasonal described here when implementing and monitoring interventions. Monitoring simple meteorological variables (i.e., temperature, rainfall) may allow prediction of VL epidemics on the Indian subcontinent. © 2010 Entomological Society of America.
Vector control by insecticide-treated nets in the fight against visceral leishmaniasis in the Indian subcontinent, what is the evidence?
(2008) Bart Ostyn; Veerle Vanlerberghe; Albert Picado; Diwakar Singh Dinesh; Shyam Sundar; François Chappuis; Suman Rijal; Jean-Claude Dujardin; Marc Coosemans; Marleen Boelaert; Clive Davies
Visceral leishmaniasis (VL) is a deadly vector-borne disease that causes an estimated 500 000 new cases a year. In India, Nepal and Bangladesh, VL is caused by Leishmania donovani, which is transmitted from man to man by the sandfly Phlebotomus argentipes. In 2005, these three countries signed a memorandum of understanding to eliminate VL from the region. Integrated vector management is one of the pillars of this elimination strategy, alongside early case detection and treatment. We reviewed the evidence of effectiveness of different vector control methods, to examine the potential role of insecticide treated bednets (ITNs). Indoor residual spraying has shown poor impact for various reasons and resistance to DDT is emerging in Bihar. Environmental management performed poorly compared to insecticide based methods. ITNs could give individual protection but this still needs to be proven in randomized trials. Given the constraints of indoor residual spraying, it is worthwhile to further explore the use of ITNs, in particular long lasting ITNs, as an additional tool in the VL elimination initiative. © 2008 Blackwell Publishing Ltd.