METHODS: Mosquito collections were carried out using human landing catches at ground and canopy levels in the Tawau Division of Sabah. Collections were conducted along an anthropogenic disturbance gradient (primary forest, lightly logged virgin jungle reserve and salvage logged forest) between 18:00 and 22:00 h.
RESULTS: Anopheles balabacensis, a vector of P. knowlesi, was the predominant species in all collection areas, accounting for 70 % of the total catch, with a peak landing time of 18:30-20:00 h. Anopheles balabacensis had a preference for landing on humans at ground level compared to the canopy (p mosquitoes were landing in the logged forest compared to the primary forest (p mosquito abundance in the logged forest and lightly logged forest (p = 0.554). A higher evening temperature (p mosquito abundance during collection nights.
CONCLUSIONS: This study demonstrates the potential ability of An. balabacensis to transmit P. knowlesi between canopy-dwelling simian hosts and ground-dwelling humans, and that forest disturbance increases the abundance of this disease vector. These results, in combination with regional patterns of land use change, may partly explain the rapid rise in P. knowlesi cases in Sabah. This study provides essential data on anthropophily for the principal vector of P. knowlesi which is important for the planning of vector control strategies.
RESULTS: HLC caught more An. balabacensis than any other method (3.6 per night). In contrast, no An. balabacensis were collected in MBT collections, which generally performed poorly for all mosquito taxa. Anopheles vector species including An. balabacensis were sampled in both HENET and MENET collections, but at a mean abundance of less than 1 per night. There was no difference between HENET and MENET in the overall abundance (P = 0.05) or proportion (P = 0.7) of An. balabacensis. The estimated diversity of Anopheles species was marginally higher in electrocuting net than HLC collections, and similar in collections made with humans or monkey hosts.
CONCLUSIONS: Host-baited electrocuting nets had moderate success for sampling known zoonotic malaria vectors. The primary vector An. balabacensis was collected with electrocuting nets baited both with humans and macaques, but at a considerably lower density than the HLC standard. However, electrocuting nets were considerably more successful than monkey-baited traps and representatively characterised anopheline species diversity. Consequently, their use allows inferences about relative mosquito attraction to be meaningfully interpreted while eliminating confounding factors due to trapping method. On this basis, electrocuting net traps should be considered as a useful standardised method for investigating vector contact with humans and wildlife reservoirs.
AIMS: This systematic review aims to determine the factors associated with mosquito control among construction workers.
METHODS: Primarily, articles related to factors associated with mosquito control among construction workers were collected from two different online databases (ScienceDirect and EBSCOhost). Two independent reviewers were assigned to screen the titles and abstracts of the collected data, stored in Microsoft Excel, against the inclusion and exclusion criteria. Afterwards, the quality of the included articles was critically assessed using the Mixed Method Appraisal Tool (MMAT). Of the 171 articles identified, 4 were included in the final review.
RESULTS: Based on the thorough evaluation, mosquito-related knowledge, practical mosquito prevention measures, and Larval Source Management (LSM) were identified as vital factors associated with mosquito control among construction workers. The significant association between mosquito-related knowledge and control practices indicates higher knowledge linked to effective practices, particularly among female workers and those who were recently infected with malaria. Concurrently, there were notable challenges regarding sustainable preventive measures and larval control methods in construction settings.
CONCLUSION: Implementing effective mosquito control, including knowledge and practice on mosquito control together with vector control, is highly required to suppress the expanding mosquito population. It is recommended that employers provide continuous mosquito control education and training to their employees and reward them with incentives, while employees should comply with the guidelines set by their employers to ensure successful mosquito control and reduce the spread of mosquito-borne diseases in the construction industry.
RESULTS: A total of 1599 Anopheles specimens were collected in the village, of which about 90% were An. balabacensis. Anopheles balabacensis was present throughout the year and was the dominant Anopheles species in all habitat types. The shrub bushes habitat had the highest Anopheles species diversity while forest edge had the greatest number of Anopheles individuals caught. GLMM analysis indicated that An. balabacensis abundance was not affected by the type of habitats, and it was more active during the early and late night compared to predawn and dawn. PCR assay showed that 1.61% of the tested An. balabacensis were positive for malaria parasites, most of which were caught in oil palm estates and infected with one to two Plasmodium species.
CONCLUSIONS: The identification of infected vectors in a range of habitats, including agricultural and farming areas, illustrates the potential for humans to be exposed to P. knowlesi outside forested areas. This finding contributes to a growing body of evidence implicating environmental changes due to deforestation, expansion of agricultural and farming areas, and development of human settlements near to forest fringes in the emergence of P. knowlesi in Sabah.
RESULTS: Over 31 days, 2243 mosquitoes were collected in 5748 discrete collections. Nine mosquito genera were sampled with Aedes and Culex species being present in all habitats and most abundant. RB and CDC backpack aspiration were most efficient for sampling Culex whereas CDC backpack aspiration and SRB were most efficient for Aedes. Most Aedes identified to species level were Ae. albopictus (91%), with their abundance being highest in forest edge habitats. In contrast, Culex were most abundant under houses. Most blood-fed mosquitoes (76%) were found in human settlements; with humans and chickens being the only blood source.
CONCLUSIONS: RB and SRB traps proved capable of sampling mosquitoes resting in all sampled habitats. However, sampling efficiency was generally low (c.0.1 per trap per day), necessitating traps to be deployed in high numbers for mosquito detection. None of the traps were effective for sampling zoonotic malaria vectors; however, SRB collected relatively higher numbers of the dengue vector Ae. albopictus. The higher abundance of mosquitoes in forest edge habitats indicates the potential value of these traps for investigating sylvatic dengue transmission. This study has demonstrated the merits in application of simple resting traps for characterising mosquito vector resting behaviour outside of the home.
METHODS: The abundance, diversity and biting behavior of human-biting Anopheles mosquitoes were assessed through monthly outdoor human landing catches (HLC) in three ecotypes representing different land use (forest edge, forest and agricultural area) across 8 months. Additionally, the host preference and biting activity of potential Anopheles vectors were assessed through comparison of their abundance and capture time in traps baited with humans (HLC, human-baited electrocuting net-HEN) or macaques (monkey-baited trap-MBT, monkey-baited electrocuting net-MEN). All female Anopheles mosquitoes were tested for the presence of Plasmodium parasites by PCR.
RESULTS: Previously incriminated vectors Anopheles balabacensis and An. flavirostris accounted for > 95% of anophelines caught in longitudinal surveillance. However, human biting densities were relatively low (An. balabacensis: 0.34-1.20 per night, An. flavirostris: 0-2 bites per night). Biting densities of An. balabacensis were highest in the forest edge, while An. flavirostris was most abundant in the agricultural area. The abundance of An. balabacensis and An. flavirostris was significantly higher in HLC than in MBT. None of the 357 female Anopheles mosquitoes tested for Plasmodium infection were positive.
CONCLUSIONS: The relatively low density and lack of malaria infection in Anopheles mosquitoes sampled here indicates that exposure to P. knowlesi in this setting is considerably lower than in neighboring countries (i.e. Malaysia), where it is now the primary cause of malaria in humans. Although anophelines had lower abundance in MBTs than in HLCs, An. balabacensis and An. flavirostris were caught by both methods, suggesting they could act as bridge vectors between humans and macaques. These species bite primarily outdoors during the early evening, confirming that insecticide-treated nets are unlikely to provide protection against P. knowlesi vectors.