Visceral Leishmaniasis (VL) is a neglected vector-borne disease. In India, it is transmitted to humans by Leishmania donovani-infected Phlebotomus argentipes sand flies. In 2005, VL was targeted for elimination by the governments of India, Nepal and Bangladesh by 2015. The elimination strategy consists of rapid case detection, treatment of VL cases and vector control using indoor residual spraying (IRS). However, to achieve sustained elimination of VL, an appropriate post elimination surveillance programme should be designed, and crucial knowledge gaps in vector bionomics, human infection and transmission need to be addressed. This review examines the outstanding knowledge gaps, specifically in the context of Bihar State, India.The knowledge gaps in vector bionomics that will be of immediate benefit to current control operations include better estimates of human biting rates and natural infection rates of P. argentipes, with L. donovani, and how these vary spatially, temporally and in response to IRS. The relative importance of indoor and outdoor transmission, and how P. argentipes disperse, are also unknown. With respect to human transmission it is important to use a range of diagnostic tools to distinguish individuals in endemic communities into those who: 1) are to going to progress to clinical VL, 2) are immune/refractory to infection and 3) have had past exposure to sand flies.It is crucial to keep in mind that close to elimination, and post-elimination, VL cases will become infrequent, so it is vital to define what the surveillance programme should target and how it should be designed to prevent resurgence. Therefore, a better understanding of the transmission dynamics of VL, in particular of how rates of infection in humans and sand flies vary as functions of each other, is required to guide VL elimination efforts and ensure sustained elimination in the Indian subcontinent. By collecting contemporary entomological and human data in the same geographical locations, more precise epidemiological models can be produced. The suite of data collected can also be used to inform the national programme if supplementary vector control tools, in addition to IRS, are required to address the issues of people sleeping outside.

This study examined the spatial distribution and seasonal fluctuations of population densities of phlebotomine sand flies and was designed to obtain baseline data on the population trends of Phlebotomus argentipes, P. papatasi, and Sergentomyia spp. in a visceral leishmaniasis endemic area of Bihar, India. Beginning on 28 October 2009 and through 20 October 2010, 63 CDC light traps were evenly distributed in human homes, cattle sheds, combined dwellings, chicken coops, and adjacent vegetation areas in three villages in the Saran District of Bihar State. Sand fly collections were made on a weekly basis, sorted, and identified according to species, sex, and feeding status of the two genera. The daily temperatures and relative humidity ranges were collected in a representative human home, cattle shed, and combined dwelling in each of the three study villages. Village census surveys were conducted in the three study villages in February 2010, acquiring human population data, structural composition data, and livestock census information, and documenting the history of visceral leishmaniasis within each household. A total of 52,653 sand flies was trapped and identified over 3,276 trap-nights. Peaks in abundance were observed in November 2009, March and April, June through August. Of the sand flies trapped, 72.1% were P. argentipes, 27.1% Sergentomyia spp., and 0.8% P. papatasi. Distribution of the sand fly captures included 30.6%, 26.7%, 18.6%, 12.1%, and 12.0% from vegetation, combined dwellings, cattle sheds, housing, and poultry houses, respectively. Journal of Vector Ecology 36 (Supplement 1): S106-S117. 2011.

BackgroundDespite the implementation of vector control strategies, including insecticide-treated bed nets (ITN) and indoor residual spraying (IRS) in western Kenya, this area still experiences high level of malaria transmission. Novel vector control tools are required which target such vector species, such as Anopheles arabiensis, that feed outdoors and have minimal contact with ITNs and IRS.MethodsTo address this need, ivermectin, eprinomectin, and fipronil were evaluated in Zebu cattle under semi-field conditions to evaluate the potential of these compounds to reduce the survival of blood feeding An. arabiensis. Over the course of four experiments, lactating cattle received doses of oral ivermectin at 0.1 or 0.2 mg/kg, oral eprinomectin at 0.2 or 0.5 mg/kg, topical eprinomectin at 0.5, 0.75, or 1.5 mg/kg, or oral fipronil at 0.25, 0.5, 1.0, or 1.5 mg/kg. On days 1, 3, 5, 7, 14, and 21 days post-treatment, cattle were exposed to An. arabiensis, and mosquito mortality post-blood feeding was monitored. For the analysis of survival data, the Kaplan–Meier estimator and Mantel–Haenszel test was used to contrast the treatment and control survival functions.ResultsAll three compounds significantly reduced the survival time of An. arabiensis. Twenty-one days post-treatment, mortality of mosquitoes fed on cattle dosed orally with 0.2 or 0.5 mg/kg eprinomectin, topically with eprinomectin at 0.5 mg/kg, or orally with either 1.0 or 1.5 mg/kg fipronil was still significantly higher than control mortality.ConclusionsThese data demonstrate the effectiveness of three insecticidal compounds administered systemically to cattle for controlling the cattle-feeding mosquito An. arabiensis. Eprinomectin and fipronil provided the longest-lasting control. Such endectocidal treatments in cattle are a promising new strategy for control of residual, outdoor malaria transmission and could effectively augment current interventions which target more endophilic vector species.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-015-0883-0) contains supplementary material, which is available to authorized users.

Identification of the source of bloodmeals in vectors plays an important role in epidemiological studies by determining the host preferences of wild sand flies in natural habitat. The anthropophilic index is a crucial component in human leishmaniasis. Bloodmeal analysis can identify the reservoir hosts of vector borne diseases. The amplification of the mitochondrial cytochrome b gene, followed by reverse line blot analysis, helps to identify the bloodmeal ingested by the wild caught sand flies. In the current study, blood fed sand flies were collected from three different villages in Bihar, India, by using Centers for Disease Control mini traps with incandescent light. Traps were placed in five different sites in the villages. Whole genome DNA was extracted from the blood fed sand flies and was amplified for the cytochrome b region, followed by reverse line blot analysis. In total, 442 blood fed sand flies were analyzed out of which 288 (65%) were positive to cytochrome b polymerase chain reaction. Humans, cattle, buffalo, and goats were the major bloodmeals identified, followed by chickens. In some of the blood fed sand flies, multiple bloodmeals were identified. In the current study, sand flies mostly fed on humans, followed by cattle, buffalo, and goats. In this regard, it is necessary to also consider cattle, buffalo, and goats when addressing vector control in Bihar, India.

Abstract. India is one of three countries that account for an estimated 300,000 of 500,000 cases of visceral leishmaniasis (VL) occurring annually. Bihar State is the most affected area of India, with more than 90% of the cases. Surveys were conducted in two villages within the Saran district of Bihar, India, from 2009 to July of 2011 to assess risk factors associated with VL. Forty-five cases were identified, and individuals were given an oral survey. The results indicated that men contracted the disease more than women (58%), and cases over the age of 21 years accounted for 42% of the total VL cases. April to June showed the highest number of new cases. Of 135 households surveyed for sleeping conditions, 95% reported sleeping outside, and 98% slept in beds. Proximity to VL cases was the greatest risk factor (cluster 1 relative risk = 11.89 and cluster 2 relative risk = 138.34). The VL case clustering observed in this study can be incorporated in disease prevention strategies to more efficiently and effectively target VL control efforts.