Passive Outdoor Host Seeking Device (POHD): Designing and Evaluation against Outdoor Biting Malaria Vectors

Abstract

<jats:p>Odor-baited devices are increasingly needed to compliment long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) for control of residual malaria transmission. However, the odor-baited devices developed so far are bulky, dependent on the source of electricity and carbon dioxide (CO<jats:sub>2</jats:sub>), and they are logistically unsuitable for scaling up in surveillance and control of malaria vectors. We designed a passive and portable outdoor host seeking device (POHD) and preliminarily evaluated suitable components against <jats:italic>Anopheles arabiensis</jats:italic> that maintains residual malaria transmission. Experiments were conducted using semifield reared <jats:italic>An. arabiensis</jats:italic> within the semifield system at Ifakara Health Institute (IHI) in southeastern Tanzania. These mosquitoes were exposed to Suna traps® baited with BG lures or source of light and augmented with carbon dioxide (CO<jats:sub>2</jats:sub>) in view of identifying best attractants necessary to improve attractiveness of designed POHD. Two Suna traps® were hanged at the corner but outside the experimental hut in a diagonal line and rotated between four corners to control for the effect of position and wind direction on mosquito catches. Furthermore, mosquitoes were also exposed to either a bendiocarb-treated or bendiocarb-untreated POHD baited with Mbita blend, Ifakara blend, and worn socks and augmented with warmth (i.e., 1.5 liter bottle of warm water) inside an experimental hut or a screened rectangular box. This study demonstrated that mosquitoes were more strongly attracted to Suna trap® baited with BG lures and CO<jats:sub>2</jats:sub> relative to those traps baited with a source of light and CO<jats:sub>2</jats:sub>. The POHD baited with synthetic blends attracted and killed greater proportion of <jats:italic>An. arabiensis</jats:italic> compared with POHD baited with worn socks. Efficacy of the POHD was unaffected by source of warmth, and it was reduced by about 50% when the device was tested inside a screened rectangular box relative to closed experimental hut. Overall, this study demonstrates that the POHD baited with synthetic blends (Mbita and Ifakara blends) and bendiocarb can effectively attract and kill outdoor biting malaria vector species. Such POHD baited with synthetic blends may require the source of CO<jats:sub>2</jats:sub> to enhance attractiveness to mosquitoes. Further trials are, therefore, ongoing to evaluate attractiveness of improved design of POHD baited with slow-release formulation of synthetic blends and sustainable source of CO<jats:sub>2</jats:sub> to malaria vectors under semifield and natural environments.</jats:p>

Visual and thermal stimuli modulate mosquito-host contact with implications for improving malaria vector control tools

“… 7 To address the malaria global challenge, various new “lure-and-kill” mosquito traps and targets are in development, aimed at reducing the vector population and ultimately the entomological inoculation rate. 4 , 5 , 8 , 9 , 10 , 11 Promising reductions in malaria transmission suggest that mass-trapping mosquitoes and “push-pull” systems 12 could play an important role in diversifying efforts to eliminate the disease in many countries. 5 …”

Knowledge, Control Practices and Treatment Seeking Behaviour Regarding Malaria Among Students of Higher Education Institutions (HEIs) in Morogoro Urban District, Eastern Tanzania

“…This is achieved through different control measures, including, among others, larval source management (LSM) [1,2], long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) [3,7], house improvements as well as topical and spatial repellents [8,11]. LLINs and IRS are the most powerful and widely deployed control measures [12,13]; their increased use has significantly reduced malaria transmission risk and burden in most malaria-endemic countries [14,15]. However, the effectiveness of LLINs and IRS is increasingly threatened by the development of resistance in the prominent malaria mosquitoes to almost all recommended classes of chemical insecticides, let alone their irregular and inappropriate use.…”