Aedes Aegypti Mosquito Control in the Dominican Republic
Total Page:16
File Type:pdf, Size:1020Kb
FINAL REPORT LETHAL OVITRAPS WITH ATTRACTANT FOR AEDES AEGYPTI MOSQUITO CONTROL IN THE DOMINICAN REPUBLIC Recommended Citation: The Zika AIRS Project (ZAP). Lethal Ovitrap Report. Rockville, MD. The Zika AIRS Project, Abt Associates Inc. Contract: GHN-I-00-09-00013-00 Task Order: AID-OAA-TO-14-00035 Submitted to: United States Agency for International Development Abt Associates Inc. 1 6130 Executive Boulevard 1 Rockville, Maryland 20852 1 T. 301.347.5000 1 F. 301.913.9061 1 www.abtassociates.com Table of Contents 1 Introduction ............................................................................................................................................................... 4 2 Study Area .................................................................................................................................................................. 4 3 Objectives ................................................................................................................................................................... 5 4 Tools ............................................................................................................................................................................ 6 5 Methodology .............................................................................................................................................................. 6 5.1 Experimental Design ....................................................................................................................................... 6 5.2 Vector Control ................................................................................................................................................ 8 6 Results ......................................................................................................................................................................... 8 6.1 Entomological surveillance ............................................................................................................................ 8 6.2 Field Study ....................................................................................................................................................... 10 6.3 Vector Control .............................................................................................................................................. 14 7 Discussion................................................................................................................................................................. 16 8 Discoveries, Challenges, and Recommendations ............................................................................................ 17 9 Bibliography .............................................................................................................................................................. 18 10 Annex ......................................................................................................................................................................... 19 1 Introduction The Dominican Republic (DR) is a Caribbean nation that shares the island of Hispaniola with the Republic of Haiti. With a population of approximately 10.6 million and an area of 48,670 square kilometers, the country is densely populated and increasingly urbanized. Due to its tropical location, the DR experiences elevated temperatures and humidity consistently throughout the year. Most of the country’s land mass sits less than 500 meters above sea level, and there are abundant sources of water. These environmental conditions make the DR an ideal location for the proliferation of mosquitoes and other vectors that may be involved in the transmission of communicable diseases. The goal of integrated vector management (IVM) is to combine different chemical, biological, environmental, and behavior measures to address variable components of the vector transmission cycle, improving efficiency in cost effectiveness, environmental management, and sustainability. Typically, an IVM program addresses specific goals for each region and its economical, logistical and technical capabilities. In this respect, it is necessary to design and implement new, viable and sustainable alternatives for limited resource countries that interrupt the Aedes aegypti life cycle reducing the transmission of arboviruses such as dengue, Zika, and Chikungunya, while keeping the risk of other highly lethal diseases (like yellow fever) at a minimum. ZAP DR has supported the Centro de Control de Vectores y Zoonosis (CECOVEZ, previously CENCET) since 2017 in the integration of the entomological surveillance method with ovitraps, measuring the adult mosquito density through egg collection and counting. Studies performed in six provinces of the Dominican Republic (La Altagracia, Azua, Espaillat, San Cristóbal, Santo Domingo, and Santiago de los Caballeros), have proven that hay infused ovitraps attract more Aedes mosquitoes than plain water ovitraps.1 The entomological surveillance of the Aedes aegypti mosquito is performed through entomological surveys at the breeding sites, where the classic aedic indexes are determined: household index, container index, and Breteau index. This information provides infestation levels as an additional entomological surveillance measure. Considering ovitraps high efficiency to capture Aedes mosquito eggs, the ZAP Project, using the lab facilities of the Universidad Autónoma de Santo Domingo (UASD), designed an IVM strategy incorporating lethal ovitraps focused on reduction of mosquito reproduction. The lethal ovitraps for this study consisted of dark colored plastic containers with a roughened surface containing Bti and 10% hay infusion that works as an attractant for pregnant females for oviposition. 2 Study Area The study area for this pilot is the Monte Plata municipality, in the Monte Plata province. This municipality is located in the south-central area of the island, with geographic coordinates of: 18° 45' 00'' N - 69° 51' 00'' W (See Figure 1 below). Weather is tropical, with an average temperature of 25.9°C and average rainfall of 1,924 mm. Monte Plata has 46,723 inhabitants, the municipal district has 26,192 people according to the 2010 national population and housing census. 1 Entomological surveys, with ovitraps, October - December 2017, ZAP Project, in 6 sentinel sites (Manoguayabo Oeste, Azua, Moca Higuey, Area 1 and Area 3 of Santiago de los Caballeros), of the Dominican Republic. Page | 4 The last entomological survey performed in the third quarter of 2017 by the Dirección Provincial de Salud de Monte Plata (local health department), found an index of 5 for A. aegypti infestation. Infestation level combines three indexes (house, container, Breteau) on a scale of 0-9. A score of 5 therefore means an elevated infestation level. Figure 1. Location of the Monte Plata province in the Dominican Republic, and division of the 4 study areas (3 intervention and 1 control). Control 2 1 3 3 Objectives General Objective The main objective of this pilot study was to establish the effectiveness of lethal ovitraps as part of an integrated mosquito control strategy, determining its feasibility and sustainability in the Dominican Republic. Specific Objectives To develop new technical tools and procedures that complement entomological surveillance and integrated vector management in the Dominican Republic; To determine the degree of attraction for mosquitoes in the oviposition stage to different Bti and hay infused combinations; To define the residual effect of different Bti concentrates with and without infusions on A. aegypti larvae; and To evaluate the impact of a mosquito control strategy that integrates lethal ovitraps and reduction of breeding sites over the aedic infestation indexes and adult mosquito density. Page | 5 4 Tools The following tools were necessary to support this study: Plastic100ml (1 liter) capacity black Digital scale from 1 to 1000 grams colored containers 2.5 liter capacity plastic containers Pellon paper Droppers Hay bales “jamos” bug nets Bacillus thuringiensis isrraelensis (1 kilo) Prokopack aspirators GPS BG traps Area maps Tables 20X magnifiers 250ml capacity container cages Flashlights 1 stereoscope (Nexius ZOOM 5 liter buckets NZ.1902-S) Sensitive precision balance (from 0.001) cellphones 5 Methodology 5.1 Experimental Design The lethal ovitraps pilot consisted of three phases: laboratory, semi-field, and field phases. 5.1.1 Laboratory Phase During the laboratory phase, we tested differences in the level of attraction of gravid mosquitoes in oviposition, using ovitraps with different concentrations of Bti, with and without hay infusion as attractant. The tests were conducted at the entomology laboratory of Universidad Autónoma de Santo Domingo. 5.1.1.1 Preference of oviposition on Bti and Bti with attractant In this experiment, differences in attraction for female gravid mosquitoes in oviposition were determined comparing the following combinations of ovitraps attractant: plain water, concentrations of 3ppm or 6ppm Bti and 10% hay infused with 3ppm or 6ppm Bti. For the oviposition experiments, San Cristobal strain 5-day-old female mosquitoes were used and kept in insectarium conditions of 26-29 C temperature, and 70-90% relative humidity. These mosquitoes were previously mated and subsequently blood-fed for 3 hours. For this, three mice of the Mus musculus species were introduced. Two days after being blood-fed, 10 randomly picked