Effectiveness and Cost of Insecticide-Treated Bed Nets and Indoor Residual Spraying for the Control of Cutaneous Leishmaniasis: A Cluster-Randomized Control Trial in Morocco.

Cutaneous leishmaniasis (CL) remains an important public health problem in Morocco. A cluster-randomized trial was conducted with the following three study arms: 1) long-lasting insecticide-treated nets (LLINs) plus standard of care environmental management (SoC-EM), 2) indoor residual spraying (IRS) with α-cypermethrin plus SoC-EM, and 3) SoC-EM alone. Incidence of new CL cases by passive and active case detection, sandfly abundance, and cost and cost-effectiveness was compared between study arms over 5 years. Incidence of CL and sandfly abundance were significantly lower in the IRS arm compared with SoC-EM (CL incidence rate ratio = 0.32, 95% confidence interval [CI] = 0.15-0.69, P = 0.005 and sandfly abundance ratio = 0.39, 95% CI = 0.18-0.85, P = 0.022). Reductions in the LLIN arm of the study were not significant, possibly due to poor compliance. IRS was effective and more cost-effective for the prevention of CL in Morocco

Insecticide susceptibility status of Phlebotomus (Paraphlebotomus) sergenti and Phlebotomus (Phlebotomus) papatasi in endemic foci of cutaneous leishmaniasis in Morocco

<p>Abstract</p> <p>Background</p> <p>In Morocco, cutaneous leishmaniasis is transmitted by <it>Phlebotomus sergenti </it>and <it>Ph. papatasi</it>. Vector control is mainly based on environmental management but indoor residual spraying with synthetic pyrethroids is applied in many foci of <it>Leishmania tropica</it>. However, the levels and distribution of sandfly susceptibility to insecticides currently used has not been studied yet. Hence, this study was undertaken to establish the susceptibility status of <it>Ph. sergenti </it>and <it>Ph. papatasi </it>to lambdacyhalothrin, DDT and malathion.</p> <p>Methods</p> <p>The insecticide susceptibility status of <it>Ph. sergenti </it>and <it>Ph. papatasi </it>was assessed during 2011, following the standard WHO technique based on discriminating dosage. A series of twenty-five susceptibility tests were carried out on wild populations of <it>Ph. sergenti </it>and <it>Ph. papatasi </it>collected by CDC light traps from seven villages in six different provinces. Knockdown rates (KDT) were noted at 5 min intervals during the exposure to DDT and to lambdacyhalothrin. After one hour of exposure, sandflies were transferred to the observation tubes for 24 hours. After this period, mortality rate was calculated. Data were analyzed by Probit analysis program to determine the knockdown time 50% and 90% (KDT50 and KDT90) values.</p> <p>Results</p> <p>Study results showed that <it>Ph.sergenti </it>and <it>Ph. papatasi </it>were susceptible to all insecticides tested. Comparison of KDT values showed a clear difference between the insecticide knockdown effect in studied villages. This effect was lower in areas subject to high selective public health insecticide pressure in the framework of malaria or leishmaniasis control.</p> <p>Conclusion</p> <p><it>Phlebotomus sergenti </it>and <it>Ph. papatasi </it>are susceptible to the insecticides tested in the seven studied villages but they showed a low knockdown effect in Azilal, Chichaoua and Settat. Therefore, a study of insecticide susceptibility of these vectors in other foci of leishmaniasis is recommended and the level of their susceptibility should be regularly monitored.</p

Potential of Aedes albopictus to cause the emergence of arboviruses in Morocco

International audienceIn 2015, the mosquito Aedes albopictus was detected in Rabat, Morocco. This invasive species can be involved in the transmission of more than 25 arboviruses. It is known that each combination of mosquito population and virus genotype leads to a specific interaction that can shape the outcome of infection. Testing the vector competence of local mosquitoes is therefore a prerequisite to assess the risks of emergence. A field-collected strain of Ae. albopictus from Morocco was experimentally infected with dengue (DENV), chikungunya (CHIKV), zika (ZIKV) and yellow fever (YFV) viruses. We found that this species can highly transmit CHIKV and to a lesser extent, DENV, ZIKV and YFV. Viruses can be detected in mosquito saliva at day 3 (CHIKV), day 14 (DENV and YFV), and day 21 (ZIKV) post-infection. These results suggest that the local transmission of these four arboviruses by Ae. albo-pictus newly introduced in Morocco is a likely scenario. Trial registration: ClinicalTrials.gov APAFIS#6573-201606l412077987v2

Ecological and Control Techniques for Sand Flies (Diptera: Psychodidae) Associated with Rodent Reservoirs of Leishmaniasis

Background:Leishmaniasis remains a global health problem because of the substantial holes that remain in our understanding of sand fly ecology and the failure of traditional vector control methods. The specific larval food source is unknown for all but a few sand fly species, and this is particularly true for the vectors of Leishmania parasites. We provide methods and materials that could be used to understand, and ultimately break, the transmission cycle of zoonotic cutaneous leishmaniasis.Methods and Findings:We demonstrated in laboratory studies that analysis of the stable carbon and nitrogen isotopes found naturally in plant and animal tissues was highly effective for linking adult sand flies with their larval diet, without having to locate or capture the sand fly larvae themselves. In a field trial, we also demonstrated using this technique that half of captured adult sand flies had fed as larvae on rodent feces. Through the identification of rodent feces as a sand fly larval habitat, we now know that rodent baits containing insecticides that have been shown in previous studies to pass into the rodents\u27 feces and kill sand fly larvae also could play a future role in sand fly control. In a second study we showed that rubidium incorporated into rodent baits could be used to demonstrate the level of bloodfeeding by sand flies on baited rodents, and that the elimination of sand flies that feed on rodents can be achieved using baits containing an insecticide that circulates in the blood of baited rodents.Conclusions:Combined, the techniques described could help to identify larval food sources of other important vectors of the protozoa that cause visceral or dermal leishmaniasis. Unveiling aspects of the life cycles of sand flies that could be targeted with insecticides would guide future sand fly control programs for prevention of leishmaniasis

Diagram of the use of stable isotope analysis to link the plants used for forage by jirds to the feces produced by these jirds and to sand flies that had fed on these feces as larvae.

<p>The δ¹³C and δ¹⁵N values of 100.0% of sand flies fed jird feces as larvae in the lab and 50.0% of sand flies captured at the study site matched the field collected jird feces. Stable isotope analysis also indicated the remaining 50.0% of sand flies captured at the study site had fed as larvae on one of two distinct alternative (and currently unknown) food sources other than jird feces.</p

Stable carbon and nitrogen isotope ratios (δ¹³C and δ¹⁵N) of feces of wild jirds, tissue of the plant fed on by jirds, and individual wild adult sand flies that had been collected near jird burrows or reared in the laboratory as larvae on field-collected jird feces.

<p>Hierarchical cluster analysis identified 3 significantly different groups of samples based on δ¹³C and δ¹⁵N values. The cluster circled in red contained feces of wild jirds, tissue of the plant fed on by jirds, individual sand flies reared in the laboratory as larvae on field-collected jird feces, and 50.0% of the sand flies captured near the jird burrows. The clusters circled in blue and yellow contained 36.4% and 13.6% of the sand flies captured near the jird burrows, respectively.</p

The mean number of females of <i>P.</i><i>papatasi</i> captured per night and the mean number of sand flies that was positive for the presence of rubidium at sites treated with rodent bait containing rubidium plus ivermectin or rubidium alone.

<p>The mean number of females of <i>P.</i><i>papatasi</i> captured per night and the mean number of sand flies that was positive for the presence of rubidium at sites treated with rodent bait containing rubidium plus ivermectin or rubidium alone.</p

Shaw's jird feeding on bait that had been placed at a study site.

<p>Shaw's jird feeding on bait that had been placed at a study site.</p

Stable carbon and nitrogen isotope ratios (δ¹³C and δ¹⁵N) of individual adult sand flies that had been reared in the laboratory on the feces of either hamsters or rabbits.

<p>Hierarchical cluster analysis identified 3 significantly different groups of samples based on δ¹³C and δ¹⁵N values. The cluster circled in red contained all sand flies reared as larvae on rabbit feces, and the cluster circled in blue contained all sand flies reared as larvae on hamster feces.</p