Lasting Insecticidal Nets Research Articles

Situation of Malaria in Kolkata Municipal Corporation area: A Secondary Data Analysis Report 2011.

A descriptive study was designed based on secondary data of Kolkata Municipal Corporation (KMC).Objectives:To estimate present status and trend of Malaria in KMC area; to determine time, place, person distribution of Malaria; to identify high-risk areas to mitigate future outbreak, and to recommend control strategies of Malaria.Materials and Methods:Three different sets of data were analyzed and the final estimate was obtained from the address confirmed database.Discussion:All the wards were high risk in boroughs 4 and 5. The Annual Blood Examination Rate (ABER) of KMC area declined to 5.29%. The falciparum percentage (Pf%) of KMC area was 8.91% in 2011. The ABER of Borough 14 was 1 but the Pf% was 14.6. “Sen Factor” may be calculated to plan the activities among the wards when the resources are limited.Conclusion:The ABER of Kolkata needs to be improved and Insecticide Treated Nets/ Long Lasting Insecticidal Nets must be considered to control the situation in addition to other regular vector-control measures and Behavior Change Communication activities. Cumulated ABER can be calculated for urban area to get an estimate of fever cases.

Indoor residual spraying with microencapsulated DEET repellent (N, N-diethyl-m-toluamide) for control of Anopheles arabiensis and Culex quinquefasciatus.

BackgroundEvolution of insecticide resistance in Anopheles gambiae complex necessitates evaluation of alternative chemical classes to complement existing insecticides for long lasting insecticidal nets (LLIN) and indoor residual spraying (IRS). Microencapsulated (MC) DEET (N, N-diethyl-m-toluamide) is a formulation of the popular repellent, which gives long lasting activity when applied to nets. Its suitability for IRS use has not been evaluated before. This study assessed the efficacy of DEET MC, for IRS in experimental huts.MethodsDEET MC was tested alongside standard repellent and non-repellent residual insecticides: lambdacyhalothrin, permethrin, pirimiphos methyl and DDT. Residual formulations of these compounds were sprayed on plywood panels attached to walls of experimental huts to assess efficacy against pyrethroid resistant, wild free-flying Anopheles arabiensis and Culex quinquefasciatus. The panel treatments were rotated weekly between huts.ResultsThe overall mortalities of An. arabiensis induced by the various treatments (range: 76-86%) were significantly greater than mortality in the untreated control (8%, P < 0.001). Mortality of An. arabiensis in DEET sprayed huts (82%) was higher than in lambdacyhalothrin CS (76%, P = 0.043) but not significantly different to pirimiphos methyl CS (86%, P = 0.204) or DDT huts (81%, P = 0.703). Against Cx. quinquefasciatus DEET MC was less effective, inducing lower mortality (29%) than other treatments. An arabiensis blood feeding rates were higher in the unsprayed control (34%) than in sprayed huts (range between treatments: 19-22%, P < 0.002), and DEET provided equivalent or superior blood feeding inhibition (44%) to other insecticides. Against Cx. quinquefasciatus there was no significant reduction in blood-feeding for any treatment relative to the control. There was a significantly higher exiting of An. arabiensis from huts sprayed with DEET (98%), lambdacyhalothrin (98%) and permethrin (96%) relative to the control (80%, P < 0.01). Exiting rates of Cx. quinquefasciatus did not differ between treatment huts and the control.ConclusionMicroencapsulated DEET acts like an insecticide at ambient temperature and induces mosquito mortality when applied to walls made from wooden panels. This trial demonstrated the potential of microencapsulated DEET to control An. arabiensis and warrants further studies of residual activity on interior substrates.

Laboratory and experimental hut evaluation of a long-lasting insecticide treated blanket for protection against mosquitoes

BackgroundLong-lasting insecticide treated blankets (LLIBs) may provide additional protection against malaria where use of long lasting insecticidal nets (LLIN) is low or impractical such as in disaster or emergency situations.MethodsInitial efficacy testing of a new candidate LLIB was carried out at LSHTM and KCMUCo, before and after washing, in cone and ball bioassays and arm-in-cage tests against pyrethroid susceptible Anopheles gambiae. A small scale field trial was conducted using veranda-trap experimental huts in northern Tanzania against wild An. arabiensis and Culex quinquefasciatus mosquitoes. Treatments included unwashed and 5 times washed permethrin treated LLIB and blankets hand-treated with permethrin (ITB), untreated blankets, and a holed unwashed Olyset net.ResultsCone test mortality was 75% for LLIB when unwashed, but decreased to 32% after 5 washes and <10% after 10 washes. In arm-in-cage tests protection against biting was 100% for LLIBs regardless of the number of washes while reduction in landings was 79% when unwashed, 75% after 5 washes, but declined to 41% after 10 and 33% after 20 washes. In ball bioassays using pyrethroid resistant An. arabiensis, mortality was low in all treatments (<35%) and there was no significant difference in mortality between Olyset net, LLIB or ITB (p > 0.05). Percentage mortality of An. arabiensis in huts with LLIB unwashed (26%) was not statistically different to Olyset net (31%, p = 0.5). The 5 times washed LLIB reduced blood-feeding by 49% which was equivalent to Olyset net (p > 0.086). There was no significant difference in percentage blood-feeding between LLIB and ITB unwashed or 5 times washed (p = 0.147 and p = 0.346 respectively). The 5 times washed LLIB reduced blood-feeding of Culex quinquefasciatus by 40%, although the Olyset provided the greatest protection with 85% inhibition. ELISA analysis of a sub-sample of blood fed mosquitoes showed that not all had fed on humans in the huts, therefore blood-feeding inhibition may have been underestimated.ConclusionsThis trial demonstrated the potential of LLIBs to provide substantial personal protection even against pyrethroid resistant mosquitoes. LLIBs may prove particularly useful where LLINs are unsuitable or net usage is low.

Indoor Application of Attractive Toxic Sugar Bait (ATSB) in Combination with Mosquito Nets for Control of Pyrethroid-Resistant Mosquitoes

BackgroundAttractive toxic sugar bait (ATSB) sprayed onto vegetation has been successful in controlling Anopheles mosquitoes outdoors. Indoor application of ATSB has yet to be explored. The purpose of this study was to determine whether ATSB stations positioned indoors have the potential to kill host-seeking mosquitoes and constitute a new approach to control of mosquito-borne diseases.MethodsInsecticides were mixed with dyed sugar solution and tested as toxic baits against Anopheles arabiensis, An. Gambiae s.s. and Culex quinquefasciatus in feeding bioassay tests to identify suitable attractant-insecticide combinations. The most promising ATSB candidates were then trialed in experimental huts in Moshi, Tanzania. ATSB stations were hung in huts next to untreated mosquito nets occupied by human volunteers. The proportions of mosquitoes killed in huts with ATSB treatments relative to huts with non-insecticide control treatments huts were recorded, noting evidence of dye in mosquito abdomens. ResultsIn feeding bioassays, chlorfenapyr 0.5% v/v, boric acid 2% w/v, and tolfenpyrad 1% v/v, mixed in a guava juice-based bait, each killed more than 90% of pyrethroid-susceptible An. Gambiae s.s. and pyrethroid-resistant An. arabiensis and Cx. quinquefasciatus. In the hut trial, mortality rates of the three ATSB treatments ranged from 41-48% against An. arabiensis and 36-43% against Cx. quinquefasciatus and all were significantly greater than the control mortalities: 18% for An. arabiensis, 7% for Cx. quinquefasciatus (p<0.05). Mortality rates with ATSB were comparable to those with long lasting insecticidal nets previously tested against the same species in this area. ConclusionsIndoor ATSB shows promise as a supplement to mosquito nets for controlling mosquitoes. Indoor ATSB constitute a novel application method for insecticide classes that act as stomach poisons and have not hitherto been exploited for mosquito control. Combined with LLIN, indoor use of ATSB has the potential to serve as a strategy for managing insecticide resistance.

Determinants of long lasting insecticidal nets distribution, ownership and use in the Federal Capital Territory, Nigeria implications for malaria programmes

A community-based household survey was conducted to investigate the ownership and utilization of malaria control commodities in the Federal Capital Territory (FCT), Nigeria, using a multifaceted four-phase operational research. The main objectives were to investigate access to and utilization of health services in the capital of the country, to evaluate Insecticide-treated nets (ITN)/long lasting insecticidal nets (LLIN) household coverage including ownership and usage and to assess progress towards achieving LLIN target in the FCT. A multifaceted four-phase operational research, consisting of a community-based household survey describing ownership and use of LLINs, a review of hospital records on malaria disease, the prevalence of malaria among children under the age of five years and use of sulphadoxine-pyrimethamine as intermittent preventive treatment in pregnancy (IPTp), was used to investigate the extent of access to health services and utilization of malaria control strategies adopted in the FCT with reference to the Roll Back Malaria initiative. Of the 585 households surveyed, only 158 (27%) reported ownership of LLINs and 427 (73%) not owning LLIN (χ² = 3.83, p < 0.05). Only 2% of adults, 7% under-fives and 19% of pregnant women, respectively slept under LLINs the night before survey. Urban under-fives were 12 times more likely to seek treatment for malaria than their semi-urban counterparts (χ² = 13.2, p = 0.0002, OR = 12.3, CI = 2.47, 61.35). There was no significant difference in the proportion of women in urban, semi-urban and rural location, who took antimalaria medication during last pregnancy or those who did not.Information, education and communication targeting health promotion on the use of LLIN in FCT could have a salutary impact on the well-being of rural, semi-urban and urban dwellers in Federal Capital Territory, Abuja, Nigeria. Key words: Community, household, malaria, long lasting insecticidal nets, Federal Capital Territory, area councils, economic burden, gross domestic product.

Impact of operational effectiveness of long-lasting insecticidal nets (LLINs) on malaria transmission in pyrethroid-resistant areas.

BackgroundA dynamic study on the transmission of malaria was conducted in two areas (R+ area: Low resistance area; R+++ area: High resistance area) in the department of Plateau in South Eastern Benin, where the population is protected by Long Lasting Insecticidal Nets (LLINs). The aim of this study was to determine if the resistance of malaria vectors to insecticides has an impact on their behavior and on the effectiveness of LLINs in the reduction of malaria transmission.MethodsPopulations of Anopheles gambiae s.l. were sampled monthly by human landing catch in the two areas to evaluate human biting rates (HBR). Collected mosquitoes were identified morphologically and female Anopheles mosquitoes were tested for the presence of Plasmodium falciparum antigen as assessed using ELISA. The entomological inoculation rate (EIR) was also calculated (EIR = HBR x sporozoitic index [S]). We estimated the parity rate by dissecting the females of An. gambiae. Finally, window catch and spray catch were conducted in order to assess the blood feeding rate and the exophily rate of vectors.ResultsAfter 6 months of tracking the mosquito's behavior in contact with the LLINs (Olyset) in R+++ and R+ areas, the entomological indicators of the transmission of malaria (parity rate and sporozoitic index) were similar in the two areas. Also, An. gambiae populations showed the same susceptibility to P. falciparum in both R+ and R+++ areas. The EIR and the exophily rate are higher in R+ area than in R+++ area. But the blood-feeding rate is lower in R+ area comparing to R+++.ConclusionThe highest entomological inoculation rate observed in R+ area is mostly due to the strong aggressive density of An. gambiae recorded in one of the study localities. On the other hand, the highest exophily rate and the low blood-feeding rate recorded in R+ area compared to R+++ area are not due to the resistance status of An. gambiae, but due to the differences in distribution and availability of breeding sites for Anopheles mosquitoes between areas. However, this phenomenon is not related to the resistance status, but is related to the environment instead.

Evaluation of New Tools for Malaria Vector Control in Cameroon: Focus on Long Lasting Insecticidal Nets

BackgroundFrom 2006 to 2011, biological activity of insecticides for Indoor Residual Spraying (IRS), conventional treatment of nets (CTNs) or long lasting insecticidal nets (LLINs) was evaluated before their approval in Cameroon. The objective of the study was to select the best tools for universal malaria vector control coverage.MethodologyBioassays were performed using WHO cones and the Kisumu susceptible strain of Anopheles gambiae s.s.. Among tested products, residual activity and wash resistance of Alpha-cypermethrin LLINs (Interceptor) and CTNs (Fendona) were assessed during 5 months in the Ntougou neighborhood.Principal FindingsAll the 14 tested products were found effective (95–100% knockdown and mortality rates), although a significant decrease of efficacy was seen with lambda-cyhalothrinWP IRS, alpha-cypermethrin CTNs and LLINs (p< 0.05). However, the efficacy of Interceptor nets did not decrease during the 5 months evaluation, even after 25 washes (0.07<p< 0.9). Meanwhile Fendona SC nets displayed a drastic decrease of activity after 5 washes, odds ratio was 3.07 (1.0–8.59).ConclusionThis study provided useful data for decision making and community education toward universal coverage of malaria vector control in Cameroon.

Long lasting insecticidal nets use, efficacy and physical integrity in a vector resistance area after a nationwide campaign in southern Benin, West Africa

Although effective malaria control measures such as long lasting insecticidal nets (LLINs) have been promoted, relatively little is known about their coverage dimension. However, usage varies among households, and such variation may seriously limit the potential impact of nets. Moreover, the efficacy of these measures against Anopheles gambiae in some departments is unknown. The objective of this study was to investigate LLINs coverage and use, and their efficacy against A. gambiae in Oueme department after a mass free distribution. A post survey campaign was undertaken in January, 2012 to assess the effect of campaign six months after LLINs (Olyset net) free distribution in southern Benin. A questionnaire has been provided to heads of 1,600 households randomly selected from four districts. Despite LLINs use reaching more than 80%, coverage was low at 50.9%. A considerable damage rate (14%) of Olyset nets after only 6 months of use was observed. Bioassays revealed inefficacy of olyset toward the local population of A. gambiae after only 6 months of use. Free distribution of LLINs rapidly improved their coverage in communities. The rapid wear observed associated with low efficacy raises the problem of the choice of impregnated materials in a context of high vector resistance to insecticides. Key words: Long lasting insecticidal nets (LLINs), olyset, efficacy, Anopheles gambiae, vector control.

Effectiveness and Compliance of Long Lasting Insecticide Nets (LLINs) on Malaria Parasitemia among Pregnant Women attending Antenatal Clinics in Port Harcourt, Rivers State

Effectiveness and Compliance of Long Lasting Insecticide Nets (LLINs) on Malaria Parasitemia among Pregnant Women attending Antenatal Clinics in Port Harcourt, Rivers State

A shift from Indoor Residual Spraying (IRS) with bendiocarb to Long-Lasting Insecticidal (mosquito) Nets (LLINs) associated with changes in malaria transmission indicators in pyrethroid resistance areas in Benin

BackgroundIndoor residual spraying (IRS) was implemented in the department of Ouémé-Plateau, southern Benin, in 2008 and withdrawn in 2011, when long lasting insecticidal nets (LLINs) were distributed to the communities that were previously targeted by IRS. Did the LLIN strategy provide a better level of protection against malaria transmission than IRS?MethodsEntomological surveillance was carried out to assess indicators of transmission risk during the last year of IRS and the first year after the LLIN intervention was put in place (2010–2011). Mosquito biting density was sampled by human landing collection (HLC). Females of Anopheles gambiae s.l. were dissected to estimate the parity rates and the blood meal index. A subsample of the An. gambiae s.l. collection was tested for presence of Plasmodium falciparum sporozoites. In addition, window exit traps and pyrethrum spray catches were performed to assess exophagic behavior of Anopheles vectors.ResultsThere were significant increases in all the indicators following withdrawal of IRS. Vector biting density (p<0.001) and longevity (OR=3.81[3.01-4.82] 95% CI; p<0.001) of the An. gambiae s.l. increased significantly; so too did the blood meal index (OR=1.48 [1.1-1.99] 95% CI; p<0.001). Entomological inoculation rate, after IRS withdrawal at one surveillance site, Adjohoun, rose two fold (9.0 infected bites/person/9 months (Apr-Dec 2011) versus 3.66 infective bites/person during the 9 months preceding IRS (Apr-Dec 2010). A second site, Missérété, experienced a six-fold increase after IRS cessation (15.1 infective bites/person/9 months versus 2.41 during IRS). Exophily after IRS cessation decreased significantly in all areas (p<0.001) suggesting that mosquitoes were more likely to rest in houses with LLINs, than in houses subjected to IRS.ConclusionLLINs did not impact on indicators of transmission to the same levels as did IRS after IRS withdrawal.

Effectiveness and Compliance of Long Lasting Insecticide Nets (LLINs) on Malaria Parasitemia among Pregnant Women attending Antenatal Clinics in Port Harcourt, Rivers State

Aim: To determine the effectiveness and compliance of Long Lasting Insecticide Nets (LLINs) on malaria parasitaemia among pregnant women attending antenatal clinics. Study Design:Cross sectional study. Place and Duration of Study:Rivers State, Nigeria, between April and September 2011. Methodology: Thick and thin blood films were made and stained using parasitological standard procedures to identify malaria parasites. Questionnaires were distributed to collect personal data of the pregnant women examined. Data gotten was analyzed with Chi-square test of significance. Results: A total of 400 pr egnant women were examined, 317(79%) used LLINs with 29(9.1%) positive formalaria parasites while 83(21%) did not use LLINs with 75 (90.4%) positive for malaria parasites (P<0.05). Pregnant women in their first, second and third trimesters that used LLINs had prevalence rates of 5.3%, 12.2% and 11.5% respectively

Status of pyrethroid resistance in Anopheles gambiae s. s. M form prior to the scaling up of Long Lasting Insecticidal Nets (LLINs) in Adzopé, Eastern Côte d’Ivoire

BackgroundThe growing development of pyrethroid resistance constitutes a serious threat to malaria control programmes and if measures are not taken in time, resistance may compromise control efforts in the foreseeable future. Prior to Long Lasting Insecticidal Nets (LLINs) distribution in Eastern Cote d’Ivoire, we conducted bioassays to inform the National Malaria Control Programme of the resistance status of the main malaria vector, Anopheles gambiae s. s. and the need for close surveillance of resistance.MethodsLarvae of An. gambiae s. s. were collected in two areas of Adzopé (Port-Bouët and Tsassodji) and reared to adults. WHO susceptibility tests with impregnated filter papers were carried out to detect resistance to three pyrethroids commonly used to develop LLINs: permethrin 1%, deltamethrin 0.05% and lambda-cyhalothrin 0.05%. Molecular assays were conducted to detect M and S forms and the L1014F kdr allele in individual mosquitoes.ResultsResistance, at various degrees was detected in both areas of Adzopé. Overall, populations of An. gambiae at both sites surveyed showed equivalent frequency of the L1014F kdr allele (0.67) but for all tested pyrethroids, there were significantly higher survival rates for mosquitoes from Tsassodji (32–58%) than those from Port-Bouët (3–32%) (p < 0.001), indicating the implication of resistance mechanisms other than kdr alone. During the survey period (May–June) in this forested area of Côte d’Ivoire, An. gambiae s. s. found were exclusively of the M form and were apparently selected for pyrethroid resistance through agricultural and household usage of insecticides.ConclusionPrior to LLINs scaling up in Eastern Côte d’Ivoire, resistance was largely present at various levels in An. gambiae. Underlying mechanisms included the high frequency of the L1014F kdr mutation and other unidentified components, probably metabolic detoxifiers. Their impact on the efficacy of the planned strategy (LLINs) in the area should be investigated alongside careful monitoring of the trend in that resistance over time. The need for alternative insecticides to supplement or replace pyrethroids on nets must be stressed.

Pyrethroid Resistance in Anopheles gambiae, in Bomi County, Liberia, Compromises Malaria Vector Control

BackgroundLong Lasting Insecticidal Nets (LLIN) and Indoor Residual Spraying (IRS) have both proven to be effective malaria vector control strategies in Africa and the new technology of insecticide treated durable wall lining (DL) is being evaluated. Sustaining these interventions at high coverage levels is logistically challenging and, furthermore, the increase in insecticide resistance in African malaria vectors may reduce the efficacy of these chemical based interventions. Monitoring of vector populations and evaluation of the efficacy of insecticide based control approaches should be integral components of malaria control programmes. This study reports on entomological survey conducted in 2011 in Bomi County, Liberia.Methods Anopheles gambiae larvae were collected from four sites in Bomi, Liberia, and reared in a field insectary. Two to five days old female adult An gambiae s.l. were tested using WHO tube (n = 2027) and cone (n = 580) bioassays in houses treated with DL or IRS. A sample of mosquitoes (n = 169) were identified to species/molecular form and screened for the presence of knock down resistance (kdr) alleles associated with pyrethroid resistance.Results Anopheles gambiae s.l tested were resistant to deltamethrin but fully susceptible to bendiocarb and fenithrothion. The corrected mortality of local mosquitoes exposed to houses treated with deltamethrin either via IRS or DL was 12% and 59% respectively, suggesting that resistance may affect the efficacy of these interventions. The presence of pyrethroid resistance was associated with a high frequency of the 1014F kdr allele (90.5%) although this mutation alone cannot explain the resistance levels observed.ConclusionHigh prevalence of resistance to deltamethrin in Bomi County may reduce the efficacy of malaria strategies relying on this class of insecticide. The findings highlight the urgent need to expand and sustain monitoring of insecticide resistance in Liberian malaria vectors, evaluate the effectiveness of existing interventions and develop appropriate resistance management strategies.

Bio-efficacy of selected long-lasting insecticidal nets against pyrethroid resistant Anopheles arabiensis from South-Western Ethiopia

BackgroundThe emergence and spread of insecticide resistance in the major African malaria vectors Anopheles gambiae s.s. and Anopheles arabiensis may compromise control initiatives based on insecticide-treated nets (ITNs) or indoor residual spraying (IRS), and thus threaten the global malaria elimination strategy.MethodsWe investigated pyrethroid resistance in four populations of An. arabiensis from south-western Ethiopia and then assessed the bio-efficacy of six World Health Organization recommended long lasting insecticidal nets (LLINs) using these populations.ResultsFor all four populations of An. arabiensis, bottle bioassays indicated low to moderate susceptibility to deltamethrin (mortality at 30 minutes ranged between 43 and 80%) and permethrin (mortality ranged between 16 and 76%). Pre-exposure to the synergist piperonylbutoxide (PBO) significantly increased the susceptibility of all four populations to both deltamethrin (mortality increased between 15.3 and 56.8%) and permethrin (mortality increased between 11.6 and 58.1%), indicating the possible involvement of metabolic resistance in addition to the previously identified kdr mutations. There was reduced susceptibility of all four An. arabiensis populations to the five standard LLINs tested (maximum mortality 81.1%; minimum mortality 13.9%). Bio-efficacy against the four populations varied by net type, with the largest margin of difference observed with the Jimma population (67.2% difference). Moreover, there were differences in the bio-efficacy of each individual standard LLIN against the four mosquito populations; for example there was a difference of 40% in mortality of Yorkool against two populations. Results from standard LLINs indicated reduced susceptibility to new, unused nets that was likely due to observed pyrethroid resistance. The roof of the combination LLIN performed optimally (100% mortality) against all the four populations of An. arabiensis, indicating that observed reductions in susceptibility could be ameliorated with the combination of PBO with deltamethrin, as used in PermaNet® 3.0.ConclusionOur results suggest that bio-efficacy evaluations using local mosquito populations should be conducted where possible to make evidence-based decisions on the most suitable control products, and that those combining multiple chemicals such as PBO and deltamethrin should be considered for maintaining a high level of efficacy in vector control programmes.

Why Use of Interventions Targeting Outdoor Biting Mosquitoes will be Necessary to Achieve Malaria Elimination.

By definition, elimination of malaria means permanent reduction to zero of locally incidence of infections. Achieving this goal among other reasons, it requires fully understanding on where and when persons are most exposed to malaria vectors as these are fundamental for targeting interventions to achieve maximum impact. While elimination can be possible in some settings with low malaria transmission intensity and dominated with late and indoor biting of vectors using Long Lasting Insecticidal Nets (LLIN) and Indoor Residual Spraying (IRs), it’s difficult and even impossible in areas with high and where majority of human exposure to transmission occurs outside human dwellings. Recently in response to wide spread use of LLIN and IRS, human risk of exposure to transmission is increasingly spread across the entire night so that much of it occurs outdoors and before bed time. This modification of vector populations and behaviour has now been reported from across Africa, Asia and from the Solomon Islands. Historical evidence shows that even in areas with intervention coverage exceeding 90% of human population it was so hard to even push prevalence down below the pre elimination threshold of 1% being compromised mainly with the outdoor residual transmission. Malaria control experts must however continue to deliver interventions that tackle indoor transmission but considerable amount of resources that target mosquitoes outside of houses and outside of sleeping hours will therefore be required to sustain and go beyond existing levels of malaria control and achieve elimination.

Residual activity and integrity of PermaNet® 2.0 after 24 months of household use in a community randomised trial of long lasting insecticidal nets against visceral leishmaniasis in India and Nepal

The World Health Organization (WHO) recommends several brands of long lasting insecticidal net (LN) for protection against insect vectors but also advises national programmes to monitor and evaluate performance under local conditions to help them select the most suitable LN for their setting. During the course of a community randomised trial of LNs against visceral leishmaniasis in northern India and Nepal, opportunity arose to assess the efficacy of PermaNet 2.0 (Vestergaard-Frandsen, Denmark) after two years of use against sandfly vectors. Between 63% (India) and 78% (Nepal) of LNs became holed over the course of two years, deltamethrin residues fell from 55 mg/m(2) to an average of 11.6 mg/m(2) (India) and 27.9 mg/m(2) (Nepal), but on the basis of bioassay criteria all LNs tested still met the WHO Pesticide Evaluation Scheme standard for LN effectiveness. Nets had on average only been washed 2.5 times (India) and 0.6 times (Nepal) by householders over the course of two years. The loss of insecticide was attributed to factors which had little or nothing to do with washing, such as handling, friction and torsion during daily use. Under conditions pertaining in this region of south Asia, and for two years at least, this brand of net continues to meet the criteria established by WHO for LNs.

Community Based Distributors and Increased Ownership of the Long Lasting Insecticidal Nets in Rural Area of Jos Plateau State

Background: The risk of malaria infection depends on the risk of being bitten by an infected mosquito, which itself depends on levels of transmission and exposure. The risk of infection leading to severe malaria disease depends on a person's immune status and access to treatment. Long lasting insecticidal nets (LLINs) have been one of the main strategies for malaria transmission reduction. LLIns are low cost and highly effective way of reducing the incidence of malaria in people who sleep under them. By preventing malaria, LLINs reduces the need for treatment and the pressure on health services. This study set out to assess the effectiveness of community based distribution in increasing ownership of LLIN in the community. Methods: it was an interventional study with a study and control group using pregnant women in Dorowa Babuje as the study group and pregnant women in Vwang as the control group, baseline data was generated using an interviewer administered questionnaire in both the study and the control group. In the study group, the women were allowed to select among them those that served as community based distributors (CBDs) who were pregnant women themselves that could read and write and understood English, Hausa and the native language Birom. Subsequently, the women were sensitized about malaria, the importance of LLINs as a means of preventing malaria and how to care for the nets. The CBD then distributed the nets to the women while in the control group, after generating the data, the women were sensitized just like the study group and informed on the possible places they could obtain the LLINs but the LLIns were not distributed them. After a period of four months, using the same interviewer administered questionnaire, data was generated in both the study and the control group to compare the pre and the post intervention result and at the end of the study period, free LLINs were then distributed to the control group. Result: Education was seen to have a statistical significant influence in the ownership of the LLINs at pre-intervention in both the study and the control groups. Ownership of LLINs increased statistically significantly in the study group from 9.8% to 97.6% (P&lt;0.0001) at post-intervention. In the control group, there was no statistically significant difference in the level of ownership of LLIN at the end of the study period (P=0.389). The ownership of the LLINs was increased 89.8% (AF=89.8%) due to the community based distributors that shared the LLINs to the pregnant women in the community. Conclusion: The distribution of the LLIN at the community level with the involvement of the community people has lead to the significant increase in the ownership of LLIN.

SP5-11 Highland malaria outbreak in Homeyo District, Papua Province, Indonesia: an entomological investigation

The first highland malaria outbreak and associated deaths was reported in May 2010 from several villages in Homeyo District, Papua Province. Homeyo is 1900 M above sea level with 15–25°C...

System effectiveness of a targeted free mass distribution of long lasting insecticidal nets in Zanzibar, Tanzania

BackgroundInsecticide-treated nets (ITN) and long-lasting insecticidal treated nets (LLIN) are important means of malaria prevention. Although there is consensus regarding their importance, there is uncertainty as to which delivery strategies are optimal for dispensing these life saving interventions. A targeted mass distribution of free LLINs to children under five and pregnant women was implemented in Zanzibar between August 2005 and January 2006. The outcomes of this distribution among children under five were evaluated, four to nine months after implementation.MethodsTwo cross-sectional surveys were conducted in May 2006 in two districts of Zanzibar: Micheweni (MI) on Pemba Island and North A (NA) on Unguja Island. Household interviews were conducted with 509 caretakers of under-five children, who were surveyed for socio-economic status, the net distribution process, perceptions and use of bed nets. Each step in the distribution process was assessed in all children one to five years of age for unconditional and conditional proportion of success. System effectiveness (the accumulated proportion of success) and equity effectiveness were calculated, and predictors for LLIN use were identified.ResultsThe overall proportion of children under five sleeping under any type of treated net was 83.7% (318/380) in MI and 91.8% (357/389) in NA. The LLIN usage was 56.8% (216/380) in MI and 86.9% (338/389) in NA. Overall system effectiveness was 49% in MI and 87% in NA, and equity was found in the distribution scale-up in NA. In both districts, the predicting factor of a child sleeping under an LLIN was caretakers thinking that LLINs are better than conventional nets (OR = 2.8, p = 0.005 in MI and 2.5, p = 0.041 in NA), in addition to receiving an LLIN (OR = 4.9, p < 0.001 in MI and in OR = 30.1, p = 0.001 in NA).ConclusionsTargeted free mass distribution of LLINs can result in high and equitable bed net coverage among children under five. However, in order to sustain high effective coverage, there is need for complimentary distribution strategies between mass distribution campaigns. Considering the community's preferences prior to a mass distribution and addressing the communities concerns through information, education and communication, may improve the LLIN usage.

Field efficacy of pyrethroid treated plastic sheeting (durable lining) in combination with long lasting insecticidal nets against malaria vectors

BackgroundInsecticide treated plastic sheeting (ITPS), sometimes known as durable lining, has potential as a long-lasting insecticidal surface for malaria vector control when used as lining for interior walls and ceilings inside the home. Against a backdrop of increasing long lasting net (LN) coverage, we examined the effect of combining permethrin-treated plastic sheeting (ITPS) with LNs in Burkina Faso.MethodsA verandah trap experimental hut trial of ITPS with or without Olyset LN was conducted in the Vallée du Kou near Bobo-Dioulasso, where the two molecular forms of Anopheles gambiae s.s., S (frequency 65%) and M (frequency 35%), occur. The S form is mostly pyrethroid resistant (Fkdr = 92%) owing to the kdr mechanism, and the M form is mostly kdr susceptible (Fkdr = 7%). The treatment arms included ITPS, Olyset, ITPS plus Olyset, ITPS plus untreated net (with or without holes), and untreated control.ResultsITPS was significantly inferior to Olyset LN in terms of mortality (37% vs 63%), blood feeding inhibition (20% vs 81%) and deterrence (0 vs 42%) effects, and hence altogether inferior as a means of personal protection (16% vs 89%). The addition of ITPS to Olyset did not improve mortality (62%), blood feeding inhibition (75%), deterrence (50%) or personal protection (88%) over that of Olyset used alone. Use of untreated nets - both holed and intact - with ITPS provided greater protection from blood-feeding. The intact net/ITPS combination killed more mosquitoes than ITPS on its own.ConclusionsAlthough ITPS has a potential role for community control of malaria, at low coverage it is unlikely to be as good as Olyset LNs for household protection. The combination of pyrethroid IRS and pyrethroid LN - as practiced in some countries - is unlikely to be additive except, perhaps, at high levels of IRS coverage. A combination of LN and ITPS treated with an alternative insecticide is likely to be more effective, particularly in areas of pyrethroid resistance.