Understanding the transmission dynamics of Leishmania donovani to provide robust evidence for interventions to eliminate visceral leishmaniasis in Bihar, India.

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

The status of bromadiolone in the United States

The anticoagulant rodenticide bromadiolone is used throughout the U.S. under a number of trade names. An expanded research program is underway within Chempar to examine the use of bromadiolone in commensal and field rodent control. Data are presented herein on the toxicology, metabolism, secondary hazards, efficacy, and formulation developments with bromadiolone. A new Maki 0.001% liquid bait is being tested and excellent control results obtained against Norway rats (Rattus norvegicus), roof rats (R. rattus), and house mice (Mus musculus). New Maki paraffin blocks containing 50 ppm bromadiolone have been developed and are soon to be on the market. Bromadiolone biodegradability in the field and in animal tissues offers promise for expanded label claims for use in urban and field situations

Development of a new bird repellent, Flight Control

In August 1995 the development of a new bird repellent, Flight Control containing anthraquinone, was initiated. A series of laboratory formulation testing, cage and pen studies were conducted. The anthraquinone discrimination threshold (concentration at which birds could detect the test material) for starlings (Sturnus vulgaris) was 151 ppm in treated feeds. The model revealed that to achieve 90% repellency with Flight Control, the treated material should receive 1,131 ppm of anthraquinone. Bird feed containing pesticide granules treated with 1% anthraquinone and control feed in a lab choice study, resulted in zero mortality in quail chicks (Colinus virginianus). Pen studies with American robins (Turdus migratorius) demonstrated Flight Control repelled the species when holly berries were treated with 500 ppm anthraquinone. Pen studies in Louisiana using Flight Control-treated rice seeds generated efficacy in excess of 90% to cowbirds (Molothrus ater) and red-winged blackbirds (Agelaius phoeniceus)

Movements of Feral Hogs in Response to Warfarin Bait Consumption

The distribution of feral hogs throughout North American has increased dramatically since their introduction. The use of toxicants has proven to be a n effective tool in controlling feral hog numbers in several countries. Using data from 13 GPS hogs, we compared movements and space use of control and treated hogs between pre-baiting and baiting phases of 3 feral hog toxicant field tests. Generalized linear mixed models were used to explain prospective changes in movements. In addition, we evaluated the distance of toxicant-killed feral hog carcasses from bait stations, roads, and cultivated crop plots. The mean distances traveled by treatment hogs between the pre-baiting and baiting periods was reduced by 43.9%, 32.1%, and 48.8% for daily, diurnal, and nocturnal periods, respectively. Daily and nocturnal movements exhibited a significant decrease between pre-baiting and baiting phases by feral hogs as a result of bait consumption. Mean space use size between the pre-baiting and baiting periods for treatment hogs was reduced by 37.5% and 30.0% for 95% MCP and 50% MCP, respectively but was not a result of bait consumption. Toxicant-killed feral hog carcass distance from bait stations, cultivated crops, and roads averaged (± SE) 919.4 ± 68.1 m, 908.9 ± 72.1 m, and 120.7 ± 34.9 m, respectively. These carcasses were never recovered from crop plots or near roads and were typically found in natural land cover types. The toxicant warfarin reduced movements of feral hogs, which in turn can reduce their damage to crop and reduce the spread of disease

Movements of Feral Hogs in Response to Warfarin Bait Consumption

The distribution of feral hogs throughout North American has increased dramatically since their introduction. The use of toxicants has proven to be a n effective tool in controlling feral hog numbers in several countries. Using data from 13 GPS hogs, we compared movements and space use of control and treated hogs between pre-baiting and baiting phases of 3 feral hog toxicant field tests. Generalized linear mixed models were used to explain prospective changes in movements. In addition, we evaluated the distance of toxicant-killed feral hog carcasses from bait stations, roads, and cultivated crop plots. The mean distances traveled by treatment hogs between the pre-baiting and baiting periods was reduced by 43.9%, 32.1%, and 48.8% for daily, diurnal, and nocturnal periods, respectively. Daily and nocturnal movements exhibited a significant decrease between pre-baiting and baiting phases by feral hogs as a result of bait consumption. Mean space use size between the pre-baiting and baiting periods for treatment hogs was reduced by 37.5% and 30.0% for 95% MCP and 50% MCP, respectively but was not a result of bait consumption. Toxicant-killed feral hog carcass distance from bait stations, cultivated crops, and roads averaged (± SE) 919.4 ± 68.1 m, 908.9 ± 72.1 m, and 120.7 ± 34.9 m, respectively. These carcasses were never recovered from crop plots or near roads and were typically found in natural land cover types. The toxicant warfarin reduced movements of feral hogs, which in turn can reduce their damage to crop and reduce the spread of disease

Efficacy of a federally approved flea bait, orally administered to white-footed mice (Peromyscus leucopus), against blood feeding Ixodes scapularis larvae under simulated field conditions

A promising alternative approach to conventional vector control practices is the use of systemic insecticides/acaricides orally administered to relevant mammalian host species to control blood feeding disease vectors. In the United States, Lyme disease continues to be the most prevalent vector-borne disease with the Centers for Disease Control and Prevention estimating approximately 500,000 Lyme disease infections each year. Previous research has demonstrated the potential usefulness of a low dose fipronil bait in controlling Ixodes scapularis larvae feeding on white-footed mice. However, no such acaricide-only product is approved for use in treating white-footed mice to control I. scapularis. The purpose of the study was to evaluate the use of a federally approved fipronil flea control bait (Grain Bait) in controlling I. scapularis parasitizing white-footed mice (Peromyscus leucopus). A simulated field trial was conducted in which Grain Bait was presented to grouped white-footed mice alongside an alternative diet for 168 h. Mice were fitted with capsules and manually parasitized with I. scapularis larvae. Replete larvae detaching from each mouse were collected and monitored for molting to nymphs. The inside of each capsule was observed to evaluate tick attachment. Blood was collected from all Treatment group mice via cardiac puncture to determine the fipronil sulfone concentration in plasma (CP) for each animal. Results indicated that Grain Bait would be consumed in the presence of an alternative diet and that bait acceptance was greater for males, relative to females. Treatment with Grain Bait prevented 100% larvae from feeding to repletion at Day 7 post-exposure and prevented 80% of larvae from feeding to repletion and 84% from molting at Day 21 post-exposure, relative to Control groups. Molted nymphs were not recovered from mice that had CP detectable ≥18.4 ng/ml. The results suggest that this federally approved flea product could be utilized for tick control and that other medically important vector-host relationships should be considered

Field tests of a warfarin gel bait for moles

This paper discusses the more common methods of mole control used in the U.S. Field efficacy data are presented with a new product, Kaput® Mole Gel Bait, containing 250 ppm warfarin. Initial field studies in St. Louis, MO with a 500-ppm warfarin bait in 1998 yielded 50% efficacy within 5 days. The following year, a 250-ppm warfarin gel bait yielded 85% efficacy after 7 days of application. Field tests conducted in Ohio resulted in 90% control of eastern moles. Results from a field test in Oregon using warfarin alternate formulation and diphacinone gel baits demonstrated 47% and 80% control of Townsend’s mole within 15 and 7 days respectively

Field tests of a warfarin gel bait for moles

This paper discusses the more common methods of mole control used in the U.S. Field efficacy data are presented with a new product, Kaput® Mole Gel Bait, containing 250 ppm warfarin. Initial field studies in St. Louis, MO with a 500-ppm warfarin bait in 1998 yielded 50% efficacy within 5 days. The following year, a 250-ppm warfarin gel bait yielded 85% efficacy after 7 days of application. Field tests conducted in Ohio resulted in 90% control of eastern moles. Results from a field test in Oregon using warfarin alternate formulation and diphacinone gel baits demonstrated 47% and 80% control of Townsend’s mole within 15 and 7 days respectively

Measures to Control Phlebotomus argentipes and Visceral Leishmaniasis in India

Visceral leishmaniasis is a deadly parasitic disease that is transmitted via the bite of a female sand fly, Phlebotomus argentipes. The highest burden of this disease is in northern India. In 2005, India embarked on an initiative with Ne­pal, Bangladesh, and the World Health Organization to eliminate visceral leishmaniasis by 2015. With the goal of 1 case in 10,000 people still unmet, it is prudent to evaluate the tools that have been used thus far to reduce vector numbers and cases of the disease. Herein, we present a review of studies conducted on vector-control strategies in India to combat visceral leishmaniasis including indoor residual spraying, insecticide-treated bed nets, environmental modification, and feed-through insecticides. This review suggests that the quality of indoor residual spraying may enhance control measures while a combination of spraying, nets, and feed-through insecticides would best confront the diverse habitats of P. argentipes