Social assessment on an integrated intervention for the prevention of Zika and other Aedes-borne diseases in pregnant women and their families in Mexico

Results of the project show that pregnant women can be provided with free or low-cost integrated interventions with methods of known efficacy (topical repellent and insecticide-treated window screens) along with educative strategies, and that they are highly motivated to use these methods to enhance maternal-child health for Zika and other Aedes-borne diseases (ABD). This is a one-page assessment/synopsis of the integrated intervention

Evaluating Over-the-Counter Household Insecticide Aerosols for Rapid Vector Control of Pyrethroid-Resistant Aedes aegypti

Vector control methods that mobilize and impact rapidly during dengue, Zika, and chikungunya outbreaks are urgently needed in urban contexts. We investigated whether one person using a handheld aerosolized insecticide could achieve efficacy levels comparable to targeted indoor residual spraying (TIRS), using pyrethroid-resistant Aedes aegypti in a semi-field setting with experimental houses in Mexico. The insecticide product (H24, a carbamate and pyrethroid mixture), available over-the-counter locally, was sprayed only on known Ae. aegypti–resting surfaces, for example, walls less than 1.5 m and dark hidden areas. In six identical houses with paired bedrooms, one bedroom was treated, and the other remained an untreated control. Each week for 8 weeks, 100 female pyrethroid-resistant Ae. aegypti were released in each bedroom and followed up daily. Mortality rates in treated bedrooms exceeded 90% for at least 2 weeks, and more than 80% (89.2; 95% CI: 79.98–98.35) for 3 weeks or more. Mortality rates in control houses were zero. Results demonstrate that the immediate impact of TIRS can be delivered by one person using existing products, at an estimated cost for the average household in Mexico of under US$3 per month. Triggered by early outbreak signs, dissemination via community hubs and mass/social media of instructions to treat the home immediately, with monthly re-treatment thereafter, provides a simple means to engage and empower householders. Compatible with integrated vector management strategies, it enables self-protection even if existing agencies falter, a situation exemplified by the potential impact on vector control of the restrictions imposed during the 2020 COVID-19 pandemic

Evaluation of insecticide-treated house screening on entomological infestation and arbovirus infection of Aedes aegypti during a Zika transmission period in Merida, Mexico

Houses are provided with long-lasting insecticidal nets (LLIN), permanently fixed with aluminium frames on doors and windows. Insecticide-treated house screening (ITS) proved to confer protection which showed 50% less chance of having indoor female Ae. aegypti in comparison with non-protected houses in urban areas of the Mexican cities of Acapulco and Merida. The brochure provides a brief encapsulation of the project and results. The study included the detection of dengue (DENV), chikungunya (CHIKV) and Zika (ZIKV) viruses. All of the project participants perceived effective mosquito reduction and recommend scaling-up of the intervention

Dengue vector management using insecticide treated materials and targeted interventions on productive breeding-sites in Guatemala

Background In view of the epidemiological expansion of dengue worldwide and the availability of new tools and strategies particularly for controlling the primary dengue vector Aedes aegypti, an intervention study was set up to test the efficacy, cost and feasibility of a combined approach of insecticide treated materials (ITMs) alone and in combination with appropriate targeted interventions of the most productive vector breeding-sites. Methods The study was conducted as a cluster randomized community trial using “reduction of the vector population” as the main outcome variable. The trial had two arms: 10 intervention clusters (neighborhoods) and 10 control clusters in the town of Poptun Guatemala. Activities included entomological assessments (characteristics of breeding-sites, pupal productivity, Stegomyia indices) at baseline, 6 weeks after the first intervention (coverage of window and exterior doorways made of PermaNet 2.0 netting, factory treated with deltamethrin at 55 mg/m2, and of 200 L drums with similar treated material) and 6 weeks after the second intervention (combination of treated materials and other suitable interventions targeting productive breeding-sites i.e larviciding with Temephos, elimination etc.). The second intervention took place 17 months after the first intervention. The insecticide residual activity and the insecticidal content were also studied at different intervals. Additionally, information about demographic characteristics, cost of the intervention, coverage of houses protected and satisfaction in the population with the interventions was collected. Results At baseline (during the dry season) a variety of productive container types for Aedes pupae were identified: various container types holding >20 L, 200 L drums, washbasins and buckets (producing 83.7% of all pupae). After covering 100% of windows and exterior doorways and a small number of drums (where the commercial cover could be fixed) in 970 study households, tropical rains occurred in the area and lead to an increase of the vector population, more pronounced (but statistically not significant) in the control arm than in the intervention arm. In the second intervention (17 months later and six weeks after implementing the second intervention) the combined approach of ITMs and a combination of appropriate interventions against productive containers (Temephos in >200 L water drums, elimination of small discarded tins and bottles) lead to significant differences on reductions of the total number of pupae (P = 0.04) and the House index (P = 0.01) between intervention and control clusters, and to borderline differences on reductions of the Pupae per Person and Breteau indices (P = 0.05). The insecticide residual activity on treated curtains was high until month 18 but the chemical concentration showed a high variability. The cost per house protected with treated curtains and drum covers and targeting productive breeding-sites of the dengue vector was $ 5.31 USD. The acceptance of the measure was generally high, particularly in families who had experienced dengue. Conclusion Even under difficult environmental conditions (open houses, tropical rainfall, challenging container types mainly in the peridomestic environment) the combination of insecticide treated curtains and to a less extent drum covers and interventions targeting the productive container types can reduce the dengue vector population significantly

A case of natural infection with Dirofilaria immitis in a coati (Nasua narica) from Mexico

This paper aims to describe the natural infection with Dirofilaria immitis in Nasua narica (white-nosed coati) from Yucatán, Mexico. Two carcasses of N. narica were collected on a highway that crosses through a dense forest with patches used for agriculture and livestock activities. We performed necropsies, and two female adult nematode parasites from the heart of one specimen were collected and preserved for their molecular identification using a conventional PCR directed at a fragment of the small subunit (18S) ribosomal RNA (18S-rRNA) gene. Bioinformatic analysis showed a similarity of 99 % with three sequences from D. immitis (two from Japan). Additionally, we performed a phylogenetic tree with the recovered sequence. All these analyses showed that D. immitis is present in N. narica from Mexico. The transmission of D. immitis toward populations of Nasua sp. may be due to indirect and accidental contact with domestic dogs or wild canids that share the same environment

Long-lasting insecticide-treated house screens and targeted treatment of productive breeding-sites for dengue vector control in Acapulco, Mexico

Background Long-lasting insecticidal net screens (LLIS) fitted to domestic windows and doors in combination with targeted treatment (TT) of the most productive Aedes aegypti breeding sites were evaluated for their impact on dengue vector indices in a cluster-randomised trial in Mexico between 2011 and 2013. Methods Sequentially over 2 years, LLIS and TT were deployed in 10 treatment clusters (100 houses/cluster) and followed up over 24 months. Cross-sectional surveys quantified infestations of adult mosquitoes, immature stages at baseline (pre-intervention) and in four post-intervention samples at 6-monthly intervals. Identical surveys were carried out in 10 control clusters that received no treatment. Results LLIS clusters had significantly lower infestations compared to control clusters at 5 and 12 months after installation, as measured by adult (male and female) and pupal-based vector indices. After addition of TT to the intervention houses in intervention clusters, indices remained significantly lower in the treated clusters until 18 (immature and adult stage indices) and 24 months (adult indices only) post-intervention. Conclusions These safe, simple affordable vector control tools were well-accepted by study participants and are potentially suitable in many regions at risk from dengue worldwide

Mosquito Excito-Repellency: Effects on Behavior and the Development of Insecticide Resistance

Mosquito’s resistance to avoiding insecticide-treated surfaces (“excito-repellency”) has two effects: irritation from direct contact with a treated area and repellency as an avoidance response to contact with treated surfaces. Nowadays, this behavior appears to reduce the success of mosquito control programs, particularly those based on insecticide-driven strategies. Different systems have been designed to assess the excito-repellency, evaluating numerous insecticides’ irritants, deterrents, and toxic properties at different concentrations. The information provides valuable insights regarding the patterns of mosquito behavior based on their physiological conditions, such as the age of the mosquitoes and the duration of the tests. However, the physiological processes resulting from chemical stimulus contact “chemoreception”) are still poorly explored and understood. This review provides an overview of insecticide effects on mosquito behavior and describes the mechanisms involved in chemical stimuli uptake, translation, and recognition