Indoor Mosquito Research Articles

Effectiveness of Transfluthrin-Coated Inflammable-Fumes Insecticide-Paper (RamboTM) in the prevention of malaria in Kano, Nigeria

Background: A 15-months community Randomized Controlled Trial was conducted with the aim of assessing effectiveness of Transfluthrin-Coated Inflammable-Fumes Insecticide-Paper (TCIP) [RamboTM] on indoor mosquitoes and malaria. Methods&Materials: The studywas conducted in two communities, Panshekara andDanbare, Kano,Nigeria randomly selected as interventionandcontrol respectively. 150households (HHDs)were systematically selected in each of the two and their doors andwindowswere ‘netted’withmesh-wire. In the intervention community there were ‘netted-alone’ and ‘netted+TCIP’ administered HHDs. Participants were allowed use of Insecticide-Treated-MosquitoNets. Additional 20 HHDs were randomly selected within the two communities as internal controls and were neither ‘netted’ nor administered TCIP. Fever, blood film microscopy for malaria parasite, haematocrit and entomological indices (indoor mosquito collection and determination of species at breeding sites) were conducted quaterly. Pyrethrum Spray Collection (PSC) technique was used to collect adult mosquitos monthly from rooms in both communities. Main malaria vector species were identified using molecular techniques (PCR). ELIZA was used to identify circumsporozoite protein (CSP) of Plasmodium falciparum. Results:A total 2565personswere studied inPanshekara (1208) and Danbare (1357). There was declining trend in malaria through 4 quarters in Panshekara compared to baseline ( 2-trend, p =0.02) and slight reduction in proportion with anaemia. In Panshekara, a total of 1592 Culex species were collected out of which 911 (57.2%) were from the internal control, 440 (27.6%)were from the screened ‘netted’ and 241 (15.1%) from ‘netted+TCIP’ treated HHDs. 396 Anopheline malaria vectors were collected out of which 339, 27 and 30 were from the control, ‘netted’ and ‘netted+TCIP’ treated sites respectively. In comparison to the baseline pre-netting phase, wire netting alone provided 51% protection against the nuisance of Culicine mosquitoes, while netting plus TCIP provided 73% protection against Culicinemosquitoes. Themainmalaria vectors species were An. gambiae s.s and An. arabiensis but An. funestus could not be analysed further. CSP of P. falciparum were seen in all the 3 vector species. Conclusion: Very slight reduction in malaria and anaemia was observed. Protection conferred by TCIP was modest against Culex spp but small against the malaria vectors. TCIP complimented netting. Trial number-ATMR2010050002022487. Pan-AfricanClinical-Trial-Group

The current status of infrastructure for monitoring the efficacy of antimalarial therapeutics in Zambia.

Sub-Saharan countries have experienced centuries of high morbidity and mortality due to malaria. In addition to insecticide-treated mosquito nets and indoor residual spraying, modern antimalarial medicines have been developed to reduce disease prevalence, although the emergence of drug-resistant strains has compromised their efficacy. The purpose of this study was to evaluate the current status of malaria diagnosis and treatment, and to monitor the therapeutic efficacy of antimalarial drugs. A descriptive cross-sectional survey was conducted from 2011 to 2013 at 10 district hospitals in Zambia designated as malaria sentinel sites as well as at the National Malaria Control Centre. District medical officers at each site completed interview questionnaires. Although basic infrastructure necessary for monitoring antimalarial drug resistance (such as laboratory, dispensary, admission ward, database unit, administration offices, bed space, examination and emergency rooms) was present at all sites, there was a shortage of licensed healthcare personnel. At some sites, antimalarial drugs were prescribed for malaria-like symptoms without diagnostic confirmation by blood smear. There was no regular monitoring of antimalarial drug resistance: only one trial was conducted among all sites in the previous 24 months. A lack of antimalarial drug resistance monitoring might be associated with personnel and funding shortages. Additional financial support would be necessary to avoid the development and spread of drug-resistant malaria in Zambia.

Efficacy of Bacillus thuringiensis var. israelensis against malaria mosquitoes in northwestern Burkina Faso.

BackgroundIn Sub Saharan Africa malaria remains one of the major health problems and its control represents an important public health measure. Integrated malaria control comprises the use of impregnated mosquito nets and indoor residual spraying. The use of drugs to treat patients can create additional pressure on the equation of malaria transmission. Vector control may target the adult mosquitoes or their aquatic larval stages. Biological larvicides such as Bacillus thuringiensis israelensis (Bti) represent a promising approach to support malaria control programs by creating additional pressure on the equation of malaria transmission.MethodsIn this study we examined the efficacy of a water-dispersible granule formulation (WDG) of the biological larvicide Bti (VectoBac®) against wild Anopheles spp. larvae. Different concentrations of the larvicide were tested in standardized plastic tubs in the field against untreated controls. In weekly intervals tubs were treated with fixed concentrations of larvicide and the percentage reduction of larvae and pupae was calculated.ResultsAll used concentrations successfully killed 100 percent of the larvae within 24 hours, while the higher concentrations showed a slightly prolonged residual effect. Natural reconolization of larvae took place after two and three days respectively, late instar larvae were not found before 5 days after treatment. For the higher concentrations, up to three days no new larvae were found, implicating that the residual effect of WDG in tropical conditions is approximately one to two days. The overall pupae reduction in treated tubs was 98.5%.ConclusionsBiological larviciding with Bti can be a promising, additional tool in the fight against malaria in Africa. Environmental particularities in tropical Africa, first and foremost the rapid development of mosquitoes from oviposition to imago have to be taken into account before implementing such counter measures in national or international vector control programs. Nonetheless biological larviciding seems to be an appropriate measure for selected conditions, offering a significant contribution to the future of malaria control.

Factors associated with dengue fever IgG sero-prevalence in South Kordofan State, Sudan, in 2012: Reporting prevalence ratios

Dengue fever (DF) is a vector-borne virus transmitted to humans by infected Aedes mosquitoes. In this study, we identified the most important factors associated with the prevalence of IgG antibodies in a border state between Sudan and the new republic of South Sudan. To quantify the association of specific factors with the prevalence of DF IgG antibodies in Lagawa among subjects aged 16-60 years in 2012. Analytical cross-sectional community-based study conducted in Lagawa in 2012. Indoor mosquito breeding was the most significant predictor affecting DF IgG serology. Household water storage was also strongly associated with the presence of IgG antibodies. Residence in urban areas, younger age and a history of travel to the Red Sea State were significant predictors of DF IgG seroprevalence in South Kordofan state. Indoor (household) behaviors associated with DF infection should be modified to mitigate the infection risk in the study area. Awareness should be raised regarding DF in Lagawa to ensure community participation in all control measures, and the surveillance system at the border between Sudan and the republic of South Sudan should be strengthened.

Monitoring Malaria Vector Control Interventions: Effectiveness of Five Different Adult Mosquito Sampling Methods

Long-term success of ongoing malaria control efforts based on mosquito bed nets (long-lasting insecticidal net) and indoor residual spraying is dependent on continuous monitoring of mosquito vectors, and thus on effective mosquito sampling tools. The objective of our study was to identify the most efficient mosquito sampling tool(s) for routine vector surveillance for malaria and lymphatic filariasis transmission in coastal Kenya. We evaluated relative efficacy of five collection methods--light traps associated with a person sleeping under a net, pyrethrum spray catches, Prokopack aspirator, clay pots, and urine-baited traps--in four villages representing three ecological settings along the south coast of Kenya. Of the five methods, light traps were the most efficient for collecting female Anopheles gambiae s.l. (Giles) (Diptera: Culicidae) and Anopheles funestus (Giles) (Diptera: Culicidae) mosquitoes, whereas the Prokopack aspirator was most efficient in collecting Culex quinquefasciatus (Say) (Diptera: Culicidae) and other culicines. With the low vector densities here, and across much of sub-Saharan Africa, wherever malaria interventions, long-lasting insecticidal nets, and/or indoor residual spraying are in place, the use of a single mosquito collection method will not be sufficient to achieve a representative sample of mosquito population structure. Light traps will remain a relevant tool for host-seeking mosquitoes, especially in the absence of human landing catches. For a fair representation of the indoor mosquito population, light traps will have to be supplemented with aspirator use, which has potential for routine monitoring of indoor resting mosquitoes, and can substitute the more labor-intensive and intrusive pyrethrum spray catches. There are still no sufficiently efficient mosquito collection methods for sampling outdoor mosquitoes, particularly those that are bloodfed.

Environmentally friendly tool to control mosquito populations without risk of insecticide resistance: the Lehmann’s funnel entry trap

BackgroundCurrent malaria control strategies have cut down the malaria burden in many endemic areas, however the emergence and rapid spread of insecticide and drug resistance undermine the success of these efforts. There is growing concern that malaria eradication will not be achieved without the introduction of novel control tools. One approach that has been developed in the last few years is based on house screening to reduce indoor mosquito vector densities and consequently decrease malaria transmission. Here screening and trapping were combined in one tool to control mosquito populations. The trap does not require an insecticide or even an attractant, yet it effectively collects incoming resistant and susceptible mosquitoes and kills them.ResultsPerformance of the funnel entry trap was tested in low and high malaria vector density areas. An overall reduction of 70 to 80% of mosquito density was seen in both. Species and molecular forms of Anopheles gambiae identification indicated no variation in the number of Anopheles arabiensis and the molecular forms of An. gambiae between houses and traps. Mosquitoes collected in the traps and in houses were highly resistant to pyrethroids (0.9 kdr-based mechanism).ConclusionThere is a global consensus that new intervention tools are needed to cross the last miles in malaria elimination/eradication. The funnel entry trap showed excellent promise in suppressing mosquito densities even in area of high insecticide resistance. It requires no chemicals and is self-operated.

Consistently high estimates for the proportion of human exposure to malaria vector populations occurring indoors in rural Africa

Background Insecticide-treated nets (ITNs) and indoor residual spraying (IRS) are highly effective tools for controlling malaria transmission in Africa because the most important vectors, from the Anopheles gambiae complex and the A. funestus group, usually prefer biting humans indoors at night.Methods Matched surveys of mosquito and human behaviour from six rural sites in Burkina Faso, Tanzania, Zambia, and Kenya, with ITN use ranging from 0.2% to 82.5%, were used to calculate the proportion of human exposure to An. gambiae sensu lato and An. funestus s.l. that occurs indoors (πi), as an indicator of the upper limit of personal protection that indoor vector control measures can provide. This quantity was also estimated through use of a simplified binary analysis (πiB) so that the proportions of mosquitoes caught indoors (Pi), and between the first and last hours at which most people are indoors (Pfl) could also be calculated as underlying indicators of feeding by mosquitoes indoors or at night, respectively.Results The vast majority of human exposure to Anopheles bites occurred indoors ( = 0.79–1.00). Neither An. gambiae s.l. nor An. funestus s.l. strongly preferred feeding indoors (Pi = 0.40–0.63 and 0.22–0.69, respectively), but they overwhelmingly preferred feeding at times when most humans were indoors (Pfl = 0.78–1.00 and 0.86–1.00, respectively).Conclusions These quantitative summaries of behavioural interactions between humans and mosquitoes constitute a remarkably consistent benchmark with which future observations of vector behaviour can be compared. Longitudinal monitoring of these quantities is vital to evaluate the effectiveness of ITNs and IRS and the need for complementary measures that target vectors outdoors.

Synergies in integrated malaria control

Synergies in integrated malaria control

Modeling the Effects of Malaria Preventative Measures

Malaria is a serious and sometimes fatal epidemic affecting nearly half of the world’s population and is the 5th leading cause of death by infectious disease world-wide. There are currently two recommended methods for prevention and eradication of the disease: insecticide-treated mosquito nets (ITNs) and indoor residual spraying (IRS), but efficacies and compliance vary from region to region. In this project, we look at the effects of ITNs and IRS as methods for eradication of malaria. To compare these methods, we develop a differential equation model and apply the next generation matrix method to determine the basic reproductive number. The differential equation model builds on classical SIR epidemiological models, with added constraints for the two preventative measures. Analysis shows that the effects of ITNs and IRS can help eradicate the disease. We find that the effect of ITNs is significantly greater than the effect of IRS. We conclude that the combination of compliance and efficacy for ITNs needs to be at least 61% and that there is no such percentage for IRS alone that will eradicate the disease. At a minimum, in combination, compliance and efficacy for ITNs needs to be at least 60% and compliance and efficacy for IRS needs to be at least 60%.

Adult Mosquito Populations and Their Health Impact around and far from Dams in Tigray Region, Ethiopia

Malaria control program in Ethiopia has a history of more than 40 years, but still now, malaria is a major cause of morbidity and mortality in Ethiopia. The objective of this study is to assess the impact of dam construction in the distribution of mosquito in intervention (dam nearby villages) and controlled (villages far from dam). Indoor adult mosquitoes were collected using 144 CDC light traps from 12 villages (6 from the intervention and 6 from the control villages) Community- based malaria parasitology was also done. Sampling was done in November 2005, December 2005, May 2006 and September 2006). A total of 1713 adult indoor mosquitoes were collected, of these, 1182 (69%) were Anopheles and 531 (31%) Culex. The prevalence of Anopheles was 45.77% in the intervention villages and 23.23% in the controlled villages (F p = 0.012). The prevalence of Anopheles increased twice in the intervention compared to the controlled villages. A total of 1436 children, 888 from intervention and 548 from control villages were examined for malaria parasitology. Only 57 children were found infected by Plasmodium species. Malaria prevalence rate was 3.97% (4.17% and 3.65% in intervention and control village, respectively)(x2 = 0.11, p= 0.7399). Among the 57 malaria positive cases in 32 (56.14%) we found P. vivax and in the 25 (43.86%) P. falciparum. We can tentatively conclude that the dams situated at 2000m and above do resulted two fold adult indoor mosquito, but do not seem to have resulted in a markedly higher incidence of malaria in the region. The study concludes that concerned authorities should take appropriate measures to improve health-care facilities for local communities when planning new irrigation schemes wherever they occur.Keywords: Anopheles, Culex, Dam, Intervention, Malaria

Controlling and sampling adult sand flies with a fumigant containing permethrin and deltamethrin

The efficacy of a new smoke-generating formulation (fumigant, MidMos Solutions Ltd., GB), containing the active ingredients permethrin and deltamethrin, was evaluated against adult sand flies in an apartment (280 m(3)), a semi-open large animal shelter (enclosing an area of 300 m(2)), a closed Bedouin animal tent (104 m(3)), and a garden (141 m(2)) enclosed by a stone wall. In each location, four cages with approx. 100 Phlebotomus papatasi were exposed to the fumigant 0.5 m and 2.0 m above ground for 15 and 60 min. Controls were kept in untreated similar rooms and there were two repetitions. In the apartment and the animal tent, a single cartridge caused 100% mortality within 15 min. In the large animal shelter, one fumigant caused mortality of 86% in the lower cages and 75% in the upper cages after 15 min. After 60 min, mortality was 94 and 87%, respectively. With two fumigants, mortality was 98.5 and 91% after 15 min and after 60 min all sand flies were dead. In the garden, one fumigant caused mortality of 93% in the lower cages and 85.5% in the upper cages after 15 min. After 60 min the mortality was 98 and 92%, respectively. With two fumigants, all flies were dead within 15 min.

Insecticide resistance in the dengue vector Aedes aegypti from Martinique: distribution, mechanisms and relations with environmental factors.

Dengue is an important mosquito borne viral disease in Martinique Island (French West Indies). The viruses responsible for dengue are transmitted by Aedes aegypti, an indoor day-biting mosquito. The most effective proven method for disease prevention has been by vector control by various chemical or biological means. Unfortunately insecticide resistance has already been observed on the Island and recently showed to significantly reduce the efficacy of vector control interventions. In this study, we investigated the distribution of resistance and the underlying mechanisms in nine Ae. aegypti populations. Statistical multifactorial approach was used to investigate the correlations between insecticide resistance levels, associated mechanisms and environmental factors characterizing the mosquito populations. Bioassays revealed high levels of resistance to temephos and deltamethrin and susceptibility to Bti in the 9 populations tested. Biochemical assays showed elevated detoxification enzyme activities of monooxygenases, carboxylesterases and glutathione S-tranferases in most of the populations. Molecular screening for common insecticide target-site mutations, revealed the presence of the “knock-down resistance” V1016I Kdr mutation at high frequency (>87%). Real time quantitative RT-PCR showed the potential involvement of several candidate detoxification genes in insecticide resistance. Principal Component Analysis (PCA) performed with variables characterizing Ae. aegypti from Martinique permitted to underline potential links existing between resistance distribution and other variables such as agriculture practices, vector control interventions and urbanization. Insecticide resistance is widespread but not homogeneously distributed across Martinique. The influence of environmental and operational factors on the evolution of the resistance and mechanisms are discussed.

Larval source management for malaria control in Africa: myths and reality.

As malaria declines in many African countries there is a growing realization that new interventions need to be added to the front-line vector control tools of long-lasting impregnated nets (LLINs) and indoor residual spraying (IRS) that target adult mosquitoes indoors. Larval source management (LSM) provides the dual benefits of not only reducing numbers of house-entering mosquitoes, but, importantly, also those that bite outdoors. Large-scale LSM was a highly effective method of malaria control in the first half of the twentieth century, but was largely disbanded in favour of IRS with DDT. Today LSM continues to be used in large-scale mosquito abatement programmes in North America and Europe, but has only recently been tested in a few trials of malaria control in contemporary Africa. The results from these trials show that hand-application of larvicides can reduce transmission by 70-90% in settings where mosquito larval habitats are defined but is largely ineffectual where habitats are so extensive that not all of them can be covered on foot, such as areas that experience substantial flooding. Importantly recent evidence shows that LSM can be an effective method of malaria control, especially when combined with LLINs. Nevertheless, there are a number of misconceptions or even myths that hamper the advocacy for LSM by leading international institutions and the uptake of LSM by Malaria Control Programmes. Many argue that LSM is not feasible in Africa due to the high number of small and temporary larval habitats for Anopheles gambiae that are difficult to find and treat promptly. Reference is often made to the Ross-Macdonald model to reinforce the view that larval control is ineffective. This paper challenges the notion that LSM cannot be successfully used for malaria control in African transmission settings by highlighting historical and recent successes, discussing its potential in an integrated vector management approach working towards malaria elimination and critically reviewing the most common arguments that are used against the adoption of LSM.

Evaluations of Attractants, Lights and Fans for Indoor Mosquito Traps against Culex pipiens (Diptera: Culicidae)

The study evaluated the efficacy of indoor LED light traps (LED‐Trap) to develop with two different LED light frequencies, three attractants, two fan speeds, and three different types of mosquito traps under laboratory conditions on collection of Culex pipiens females. The attractants tested were various concentrations of lactic acid, ammonia solution and ammonium hydrogen carbonate. Four repetitions of the study were performed in each 20 or 50 Cx. pipiens in an 1.8 m x 3.7 m x 1.8 m screened enclosure. Collection rates of Cx. pipiens were not significantly different in the traps between 380 nm (mean 76.5% of a collection rate) and 400 nm (mean 96.0%) of wavelengths from the LED light traps for 14 hour operations. Without lights, the rates were not significantly different among the three different traps such as Nozawa (mean 70.7% of a collection rate), Black‐hole (mean 80.0%) and the LED‐Trap of fan speed 2,600 rpm (mean 74.7%) but they were all significantly higher than that of the LED‐Trap of a fan speed 1,350 rpm (mean 29.3%) for 14 hours. Three different concentrations of lactic acid baits in the M‐traps were not significantly different collection rates among 500, 1,000, 10,000 ppm with average collection rates of 80.0%, 93.0%, and 81.5% after 14 hour operations, respectively. Culex pipiens were not more significantly captured in the LED‐traps using five concentrations of ammonia solutions from 100 ppm to 20,000 ppm compared with those of control traps. However, the traps with ammonium hydrogen carbonate collected more mosquitoes of the averages of 26.3%, 22.5%, 43.8% at 1,000, 10,000, 20,000 ppm than control traps (fan only), respectively. Further work is needed to investigate the bait chemicals.

Natural Plant Sugar Sources of Anopheles Mosquitoes Strongly Impact Malaria Transmission Potential

An improved knowledge of mosquito life history could strengthen malaria vector control efforts that primarily focus on killing mosquitoes indoors using insecticide treated nets and indoor residual spraying. Natural sugar sources, usually floral nectars of plants, are a primary energy resource for adult mosquitoes but their role in regulating the dynamics of mosquito populations is unclear. To determine how the sugar availability impacts Anopheles sergentii populations, mark-release-recapture studies were conducted in two oases in Israel with either absence or presence of the local primary sugar source, flowering Acacia raddiana trees. Compared with population estimates from the sugar-rich oasis, An. sergentii in the sugar-poor oasis showed smaller population size (37,494 vs. 85,595), lower survival rates (0.72 vs. 0.93), and prolonged gonotrophic cycles (3.33 vs. 2.36 days). The estimated number of females older than the extrinsic incubation period of malaria (10 days) in the sugar rich site was 4 times greater than in the sugar poor site. Sugar feeding detected in mosquito guts in the sugar-rich site was significantly higher (73%) than in the sugar-poor site (48%). In contrast, plant tissue feeding (poor quality sugar source) in the sugar-rich habitat was much less (0.3%) than in the sugar-poor site (30%). More important, the estimated vectorial capacity, a standard measure of malaria transmission potential, was more than 250-fold higher in the sugar-rich oasis than that in the sugar-poor site. Our results convincingly show that the availability of sugar sources in the local environment is a major determinant regulating the dynamics of mosquito populations and their vector potential, suggesting that control interventions targeting sugar-feeding mosquitoes pose a promising tactic for combating transmission of malaria parasites and other pathogens.

Evaluation of Bifenthrin 80 SC, as a wall treatment against Culex quinquefasciatus Say (Diptera: Culicidae), a vector of Wuchereria bancrofti Cobbold, an etiological agent of Human Lymphatic Filariasis

AbstractThe mosquito, Culex quinquefasciatus Say, is a vector of Wuchereria bancrofti Cobbold, an etiological agent of Human Lymphatic Filariasis (HLS), which, in its more extreme manifestations is known as elephantiasis. This debilitating disease is still prevalent in many tropics and subtropics, particularly in the Old World tropics. The efficacy of the pyrethroid insecticide Bifenthrin as a potential insecticide for treatment of indoor building walls against Cx. quinquefasciatus was evaluated under laboratory conditions. Six concentrations (0.1, 0.2, 0.3, 0.4, 0.5 and 0.6 percent) of insecticide were sprayed. Knockdown and mortality of mosquitoes were recorded after 5, 15, 30, 60 minutes as well as 6 and 24 hours following exposure. The knockdown effects were positively correlated with the dose and exposure period. The mean percent mortalities for the above mentioned doses after 24 hours of exposure were 11.67%, sx = 0.31; 73.33, sx = 3.33; 80.00, sx = 0.37; 81.67, sx = 0.31; 81.67, sx = 0.31; 83.33, sx = 2.10; 89.00, sx = 2.23, respectively, while the LC50 and LC90 were 0.53 and 1.002 percent respectively. Residual potentiality was tested up to 5 days with the three higher doses where nearly 80% death was recorded at 0.6% concentration after 120 hours of exposure. Bifenthrin 80 SC could be used successfully to control indoor mosquito populations.

Evaluation of malaria prevention strategies during pregnancy in Ndola, Zambia

ABSTRACTBackgroundMalaria in pregnancy is associated with many negative outcomes for the woman, foetus and neonate. Intermittent preventive treatment during pregnancy (IPTp) using three doses of sulfadoxine/pyrimethamine (SP), insecticide-treated mosquito nets (ITNs) and indoor residual spray (IRS), constitute the main strategies used to prevent malaria. The aim of this study is to evaluate the effectiveness of these strategies for the reduction of malaria prevalence in pregnant women.MethodsA questionnaire on socio-demographic information, history of malaria during current pregnancy and prevention strategies used was administered to 450 consecutive patients admitted into labour wards at three local clinics. From the antenatal cards, information was collected on the last menstrual period, date of each dose of SP taken, gravidity, and HIV status. A blood slide to detect Plasmodium was then collected from each woman after consent.ResultsOf the participants in the study, 2.4% had a positive blood slide at term and 15.8% reported malaria during pregnancy. All the participants took at least one dose of SP with 87.6% completing the stipulated three doses. The mean gestational ages for each dose were 22.1 (SD 4.6), 29.1 (SD 4.4) and 34.4 (SD 3.9) weeks for the first, second and third dose respectively. With regard to ITNs, 79.5% had one, but only 74.1% used it regularly. IRS was completed in all three of the clinics’ catchment areas. Only 23.4% used commercial insecticide.ConclusionThe measured prevalence of malaria at term in Ndola was remarkably low, although the self-reported rate during pregnancy was still high. The national targets for accessing IPTp were exceeded, although the timing of each dose needs to be improved. Access to ITNs was high, but usage needs to increase.

Pengaruh Pengasapan (Thermal Fogging) Insektisida Piretroid (Malation 95%) Terhadap Nyamuk Aedes aegypti dan Culex quinquefasciatus di Pemukiman

Abstracts. The evaluation of piretroid insecticide (active ingredient Malation 95%) was con­ducted in Sub district Tengarang, Semarang Segency, Central Java Province. The insecti­cide was applied using thermal fogging method for dosages of 125, 250, 375, 500 and 625 ml/ha (diluted in diesel to 10 litters). The evaluation of the efficacy was conducted against two mosquito species, Aedes aegypti (the main dengue haemorrhagic fever) and Culex quinquefasciatus (the urban lymphatic fil­ariasis vector). Result of the evaluation was revealed that dosages of 500 and 625 ml/ha were effective against both tested mosquito species indoor and outdoor.Key Word: Aedes aegypti, Culex quinquefasciatus, insecticide Piretroid (Malation 95%), thermal fogging.

Effect of two different house screening interventions on exposure to malaria vectors and on anaemia in children in The Gambia: a randomised controlled trial

House screening should protect people against malaria. We assessed whether two types of house screening--full screening of windows, doors, and closing eaves, or installation of screened ceilings--could reduce house entry of malaria vectors and frequency of anaemia in children in an area of seasonal malaria transmission. During 2006 and 2007, 500 occupied houses in and near Farafenni town in The Gambia, an area with low use of insecticide-treated bednets, were randomly assigned to receive full screening, screened ceilings, or no screening (control). Randomisation was done by computer-generated list, in permuted blocks of five houses in the ratio 2:2:1. Screening was not treated with insecticide. Exposure to mosquitoes indoors was assessed by fortnightly light trap collections during the transmission season. Primary endpoints included the number of female Anopheles gambiae sensu lato mosquitoes collected per trap per night. Secondary endpoints included frequency of anaemia (haemoglobin concentration <80 g/L) and parasitaemia at the end of the transmission season in children (aged 6 months to 10 years) who were living in the study houses. Analysis was by modified intention to treat (ITT), including all randomised houses for which there were some outcome data and all children from those houses who were sampled for haemoglobin and parasitaemia. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN51184253. 462 houses were included in the modified ITT analysis (full screening, n=188; screened ceilings, n=178; control, n=96). The mean number of A gambiae caught in houses without screening was 37.5 per trap per night (95% CI 31.6-43.3), compared with 15.2 (12.9-17.4) in houses with full screening (ratio of means 0.41, 95% CI 0.31-0.54; p<0.0001) and 19.1 (16.1-22.1) in houses with screened ceilings (ratio 0.53, 0.40-0.70; p<0.0001). 755 children completed the study, of whom 731 had complete clinical and covariate data and were used in the analysis of clinical outcomes. 30 (19%) of 158 children from control houses had anaemia, compared with 38 (12%) of 309 from houses with full screening (adjusted odds ratio [OR] 0.53, 95% CI 0.29-0.97; p=0.04), and 31 (12%) of 264 from houses with screened ceilings (OR 0.51, 0.27-0.96; p=0.04). Frequency of parasitaemia did not differ between intervention and control groups. House screening substantially reduced the number of mosquitoes inside houses and could contribute to prevention of anaemia in children. Medical Research Council.

House design modifications reduce indoor resting malaria vector densities in rice irrigation scheme area in western Kenya

BackgroundSimple modifications of typical rural house design can be an effective and relatively inexpensive method of reducing indoor mosquito vector densities and consequently decreasing malaria transmission. Public health scientists have shown the potential for house design to protect people against malaria, yet this type of intervention remains virtually ignored. A randomized-controlled study was, therefore, undertaken to determine the effects of this method of vector control on the density of indoor resting malaria vectors in a rice irrigation scheme area in lowlands of western Kenya.MethodsTen treatment houses were modified with ceilings of papyrus mats and insecticide-treated netting (ITN) and tested against ten control houses without papyrus ceilings. To determine densities of mosquitoes resting in homes, the pyrethrum spray method was used to simultaneously collect indoor resting malaria vectors in intervention and control houses. Each house was sampled a total of eight times over a period of four months, resulting in a total of 80 sampling efforts for each treatment. Community response to such intervention was investigated by discussions with residents.ResultsPapyrus mats ceiling modification reduced house entry by Anopheles gambiae s.l and Anopheles funestus densities by between 78–80% and 86% respectively compared to unmodified houses. Geometric mean density of Anopheles gambiae s.l. and Anopheles funestus in modified houses were significantly lower (t18 = 7.174, P < 0.0001 and t18 = 2.52, P = 0.02, respectively) compared to controls. Unmodified houses were associated with relatively higher densities of malaria vectors. There was a 84% (OR 0.16, 95% CI 0.07–0.39, P < 0.0001) and 87% (OR 0.13, 95% CI 0.03–0.5, P = 0.0004) reduction in the odds of Anopheles gambiae s.l. and Anopheles funestus presence in modified houses, respectively, compared with unmodified houses. Residents responded favourably to this mode of vector control.ConclusionHouse modifications involving insect screen ceilings made from locally available materials and small ITN incorporated in house construction have the potential to reduce human exposure to malaria vectors, and thus parasite infection, in a rice irrigation scheme area of western Kenya. Ceiling modification is likely to be acceptable and is expected to be of greatest benefit when used in combination with other malaria control strategies.