Evaluation of the Use of Long-Lasting Impregnated Mosquito Nets (LLINs) in the Health District of Dimbokro (Center of Côte d’Ivoire)

The Dimbokro health district has one of the highest incidences of malaria in Côte d’Ivoire, despite numerous campaigns to distribute Long-Acting Impregnated Mosquito Nets (LLINs). Given this observation, what are the population’s attitudes towards LLINs that could explain the high endemicity of malaria in Dimbokro? The aim of this study is to assess the knowledge, attitudes and practices of people in the health area of Nofou, one of the villages in the Dimbokro health district where malaria is most prevalent, with a view to strengthening malaria control strategies. A collection of historical health data (malaria cases and LLIN usage rates) and a cross-sectional questionnaire survey was carried out from July 20 to August 03, 2022 in 400 households selected by systematic random sampling. Data were entered using Epi Info 7 and multivariate statistical analyses were performed using IBM SPSS 22 software. In the Dimbokro health district, the rate of LLIN use was negatively correlated (r = -0.771) with malaria incidence over the six years of historical data collection. Households had an average of 53% good knowledge, 68.6% good practices and 28.4% good attitudes towards LLINs. The study also revealed that the main factors explaining LLIN use in the Nofou health area are mosquito bite (ORa = 5.29 (1.12 - 25.04)), age of household members (ORa = 1.07 (1.01 - 1.14)) and marital status (ORa = 8.45 (1.70 - 45.02)). Awareness-raising on the use of LLINs should be intensified in the Dimbokro health district. Other control strategies, such as vector control and environmental sanitation, should be considered to combat malaria.

Post-intervention assessment of long-lasting insecticide nets (LLINs) distributed in the Kano metropolis, Kano State, Nigeria

Kano state has distributed about 4,137,464 Long Lasting Insecticide Nets (LLINs) in 2009 being one of the main malariavector control strategy developed by the Nigeria Federal Ministry of Health(FMOH) in line with Roll Back Malaria. The objective of the study was to evaluate the effectiveness of LLINs in use, the knowledge, attitude and practicesof some net users inthe Kano metropolis. A Cone bioassay with laboratory reared Anopheles was performed. Knock down after 60 minutes and mortality after 24 hours followed with a 3 minutes exposure were evaluated. A total of 210 households were administered with a structured questionnaire on two hundred and five (205) respondents (97.6%) indicated knowledge about LLINs while five (5) respondents (2.4%) were not aware. Very high and consistent knockdown and mortality in all 5 replicates were found. Respondent still holds some reservation on the use of LLINs, and one hundred and five respondents (54.8%) believed it causes heat. The respondents replied that they did not rely mostly on LLINs, despite their beliefs in the efficacy of it rather. 41.4% of the people that participated in the research still resorted to use of aerosols and 26.2% use smoke screens to prevent mosquito bites. It can be concluded from the findings that respondents were aware of long lasting insecticide net and agreed on its effectiveness against the vector of malaria parasite and other insects, with some having reservations on the use of smoke screens and indoor residual insecticide sprays to prevent mosquitobites. Considering that the nets are expected tobe effective for three years or more years, it is reasonable to conclude that the nets were effective in preventing mosquito bites based on the knock-down and exposure mortality results obtained during this study.

Evaluation at the Level of Health Facilities, of the Protective Efficacy of LLINs in Children under 5 Years Old from Localities of Low and High Resistance of Vectors to Pyrethroid Insecticides in Benin in West Africa

Context: The resistance to pyrethroids in malaria vectors continues to grow in Africa and could therefore compromise or reduce substantially the effectiveness of LLINs in preventing malaria. It is therefore of paramount importance to evaluate the protective efficacy of LLINs in children sleeping in areas of vector resistance to insecticides in order to draw lessons for future interventions. This study assesses the effect of the use of LLINs on malaria morbidity in clusters of low and high resistance of vectors to pyrethroids. Methods: This is a cross-sectional case-control study with one control for one case that was conducted in the communes of Kétou, Ifangni, Kétou, and Pobè in the Plateau department of southern Benin. The use of LLINs and malaria morbidity was measured and compared in children from clusters of low and high vector resistance to insecticides. In each commune, 30 cases and 30 controls were recruited for a total of 240 children under 5 years of age from villages with low and high insecticide resistance. Results: According to the localities of origin of the children, of all parents of children surveyed, 169 (70.4%) asserted the children slept under an LLIN the day before they arrived at the health center. This rate represents 70.8% (85 children) among the cases and 70.0% (84 children) among the controls without significant difference (p = 0.8). The use of LLINs the day before the survey, the frequency of their use during the two weeks preceding the day of the survey, their availability at the household level, the use of other tools for protection against mosquito bites are the same in the two groups of children (cases and controls) (p > 0.05) as well in low and high resistance villages. On the other hand, the parasite prevalence, the splenomegaly and the geometric means of the parasite densities, are significantly higher in the cases than in the controls (p Conclusion: The evaluation of epidemiological indicators in children under five years old at the level of health centers did not enable demonstrating the impact of resistance on the operational effectiveness of the LLINs. The information collected within the four health facilities only reflects the situation that should normally be seen in the population under the real conditions of use of LLINs in high and low resistance areas.

溴氰菊酯长效驱蚊帐灭蚊效果观察

为观察0.3%溴氰菊酯长效驱蚊帐对蚊虫的杀灭效果,参照NY/T 1151.4—2012标准进行实验室和模拟现场药效测试。结果显示,0.3%溴氰菊酯长效驱蚊帐在接触试验中,洗涤前、洗涤10次与洗涤20次后,对淡色库蚊1 h平均击倒率分别为100%、96.49%、93.94%;在模拟现场试验中,0.3%溴氰菊酯长效驱蚊帐洗涤20次后,对淡色库蚊12 h平均击倒率为93.68%,24 h平均死亡率为93.68%。试验表明,0.3%溴氰菊酯长效驱蚊帐具有持久、有效的防蚊灭蚊效果。

Human Habitats and Malaria Vector Control in Benin: Current Situation and Implications for Effective Control

Long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS) are the main indoor malaria vector tools control tools. The study examined housing characteristics and investigated the relationship between the total volume of household possessions, the volume of the sleeping room, and the hanging of LLINs. A total of 831 bedrooms were randomly selected in Benin in 2015. The findings showed that mud walls were predominant in rural areas (more than 75%), while metal roofs were common (77.3% - 97.9%). Battery-powered lighting was prevalent in rural areas in Northern (97%), while open-flame oil lamps were commonly used in rural areas in Southern (86%). The availability of correct bedding was low, ranging from 1% to 10% in all households. 20% of the bedrooms had at least 50% of their volume occupied by household possessions in urban areas. In rural areas, bedrooms without LLINs had a lower mean rate ratio of the volume occupied by possessions per the total volume of the room compared to bedrooms with at least one LLIN installed (p < 0.0001). The characteristics of human habitats are not favourable to the correct use of vector control intervention indoors. It is therefore important to improve people’s living conditions as the next step for malaria elimination.

Evaluation of the Anti-Salivary IgG Response Specific to Anopheles Vectors of Malaria in Children under Five Seen in Health Care Settings in Areas of Low and High Insecticide Resistance in Southern Benin

The widespread use of long-lasting insecticidal nets (LLINs) is a major intervention method for malaria control. While coverage of LLINs has increased, there is a need for information on the operational effectiveness of nets deployed in the field in the context of malaria vector resistance to insecticides used for impregnation. The development of specific anti-malarial biomarkers to assess exposure to mosquito bites is an important development in evaluations. The aim of this study was to characterize the human IgG antibody response to Anopheles gSG6-P1 saliva, a salivary peptide antigen previously shown to be a relevant biomarker of human exposure to Anopheles bites, in order to assess the LLINs under field conditions in areas of low and high vector resistance to insecticides. We analyzed data from 240 randomly selected children ( 0.05). Furthermore, the same finding was observed for antibody expression in children whether or not they used LLINs on the day before the survey (p = 0.7724). Similarly, gender and especially age, major factors of variation in the adaptive immune response, did not have a significant effect on IgG expression.

Factors Associated with Low Use of Insecticide-Treated Nets among Children under 5 Years of Age in Fo-Boure (Benin) in 2019

Despite the free distribution of insecticide impregnated nets, malaria is still the cause of many deaths, particularly among children under 5 years old, casting doubt on the real use of these mosquito nets by parents. The present work aimed to identify the factors associated with the low use of mosquito nets. This was a cross-sectional study with an analytical aim, carried out in the locality of Fô-Bouré (Sinendé) in 2019 among children under 5 years old and their parents. A cluster random sampling was carried out according to the WHO technique. The dependent variable was the low use of LLINs and the independent variables were: socio-demographic, economic, relative to parents’ knowledge of the causes and control methods of malaria. Results: The factors identified as associated with the low use of LLINs were: female sex (p = 0.0059), low level of education (p = 0.0001), free mode of acquisition (p = 0.0476), poor knowledge of control methods (p = 0.0389), type of house: mud or tent house (p = 0.0034), unsanitary immediate environment (p = 0.0002) and children’s evening dressing style (p = 0.0001). Conclusion: A global development policy, especially in terms of education, sanitation and housing improvement as recommended by the “Roll Back Malaria” initiative is necessary to improve the rate of insecticide impregnated nets use. .

Improving the Use of Insecticide-Treated Nets among Children under Five Years Old in Benin, West Africa

Background: In Benin, malaria represents the first cause of consultation and hospitalization (48% for children under 5 years old) in health units. It also accounts for 23.1% of deaths recorded in health facilities (MoH, 2019). Between the two main components of vector control adopted by Benin government, the mass distribution campaigns of Insecticide-Treated Nets (ITNs) remained the only proven cost-effective way to rapidly achieve high and equitable coverage (WHO, 2017). After the fourth mass distribution campaign conducted in 2017, the Demographic and Health Survey (DHS) data indicated that the percentage of children who slept under an ITN has increased from 20% in 2006 to 70% in 2011-2012 and to 76% in 2017-2018 while the incidence of malaria (tested positive) is increasing rapidly among children under 5 years old, growing from 36.5% in 2009 to 28.8% in 2012 and then to 51.4% in 2019. This study aims to understand this contrast by identifying the origin of the increase in ITN use over time among children under five years old and the factors which determine this use. Methods: Data from the Demographic and Health Survey (DHS) conducted in Benin respectively in 2006 and in 20018 were used during the analysis, which covered 13,445 children under five years old from 2006 DHS and 12,255 children from 2017-2018 DHS. Firstly, the data were analyzed using decomposition method to highlight the origin of the increase of ITN use over time among children under five years old. Secondly, the chi-square test analysis estimated the association between ITN use and some characteristics (wealth index, maternal or caregiver education level and child age). Finally, the logistic regression model was used to identify the main factors, which influence the net use over the study period. Results: This study shows that the improvement of basic conditions is the main origin of behavior change in the use of ITNs among children under five years old. This improvement of the basic conditions consists of making ITNs available in households and informing household members about the benefits of ITN use. So, the free ITN distribution campaigns, routine distribution, awareness campaigns about the benefits of ITN use are the strategies, which increase the household capacities and knowledge, allowing household members to make their children sleep under net. The analysis also shows that region of residence, wealth index of household, household size, religion, and child age continue to determine the ITN use among children under age 5 years old and MNCP will integrate the factors in malaria prevention strategies in order to achieve universal use of ITNs. Conclusions: Although, sleeping under ITN behavior has indeed spread among children under 5 years old, policymakers and other stakeholders should design strategies to maintain and improve the current level of ITN use to reach the collective protection threshold (80% according to WHO). Therefore, to address the challenges of universal use of ITN, the study recommends expanding the routine distribution system to private sector health centers;discussing issues related to health service utilization (particularly ITN use) within a consultation framework at the communal level. In addition, collecting qualitative and quantitative data in the Oueme region will allow better understanding of all aspects of the ITN use gap among children under 5 years.

伏诺拉生联合铋剂等四联疗法治疗幽门螺杆菌感染的效果探讨

目的:探讨伏诺拉生联合铋剂等四联疗法治疗幽门螺杆菌感染的效果。方法:选择2022年6月至11月在上海孟超肿瘤医院消化内科门诊就诊且初诊为Hp感染的120例患者为研究对象,随机分为研究组和对照组。研究组60例患者使用伏诺拉生联合铋剂等四联疗法(伏诺拉生+阿莫西林+克拉霉素+胶体果胶铋)治疗,对照组60例患者使用艾普拉唑联合铋剂等四联疗法(艾普拉唑+阿莫西林+克拉霉素+胶体果胶铋)治疗。比较两组治疗后的Hp根除率,并对其治疗期间发生不良反应的情况进行统计对比。结果:两组患者均完成治疗,无患者中途退出。治疗后行13C呼气试验的结果显示,研究组的Hp根除率为93.33%,与对照组的91.67%相比差异无统计学意义(P>0.05)。治疗期间,研究组中发生不良反应的患者共有8例,其中口苦1例,恶心2例,腹胀3例,黑便2例;对照组中发生不良反应的患者共有10例,其中黑便3例,口苦2例,腹胀3例,头痛2例。两组患者的上述不良反应均较轻,无需特殊处理,且停药后均消失。治疗期间,研究组的不良反应发生率为13.33%,对照组的不良反应发生率为16.66%,二者相比差异无统计学意义(P>0.05)。结论:伏诺拉生联合铋剂等四联疗法治疗Hp感染的效果及安全性与艾普拉唑联合铋剂等四联疗法相当。考虑本研究中样本量较小,建议扩大样本量后进行多中心研究。

徽州民居过渡季热环境分析

为掌握徽州民居过渡季室内热舒适及室内热环境差异性,对当地典型传统民居与新民居室内外过渡季热环境参数进行实测,测试结果表明秋季室外温湿度均高于春季,春季气温更为稳定。传统民居中不同空间温湿度差异不大,地垄具有良好的保温防潮作用。民居室内湿度较为适宜,温度在18℃以下所占比例较大,新民居较传统民居保温性能更好。

中缅边境缅甸克钦邦第二特区长效蚊帐发放使用情况

目的了解中缅边境缅甸克钦邦第二特区长效蚊帐发放使用情况,为开展长效蚊帐发放工作提供参考。方法收集整理2008～2009年中缅边境缅甸克钦邦第二特区长效蚊帐发放情况,并抽样调查该特区3个自然村177户家庭长效蚊帐发放使用情况。结果 2008～2009年该特区共发放了10517顶长效蚊帐,覆盖当地居民8 930户44 022人以及中国在缅务工人员1 050人。抽样调查发现,长效蚊帐发放1年半后,长效蚊帐拥有率达85.88%,86.58%的家庭经常悬挂长效蚊帐,36.84%认为使用长效蚊帐可以防止得疟疾。31.78%的长效蚊帐有轻微破损,另有8.57%的长效蚊帐破损严重已无法使用。结论中缅边境缅甸克钦邦第二特区长效蚊帐发放达到了预期效果,但今后应加强长效蚊帐使用健康教育活动,定期评估长效蚊帐质量与发放效果。

Knowledge &Utilization of Long Lasting Impregnated Nets among Housewives in Al Moneera City and Al Koozi Villages, Hodieda Governorate, Republic of Yemen 2007

Malaria is considered as one of the main health problem in the Republic of Yemen. In February 2006 National Malaria Control Program started freely distribution of Long Lasting Impregnated Nets (LLINs) for vulnerable groups to malaria infection (pregnant women and children under 5 years). After one year of distribution, there is a need to measure the use rate among vulnerable groups and explore factors affecting their use. The aim of the study was to investigate the use rate of long lasting impregnated nets among children under five years and pregnant women in Al Moneera city and Al Koozi villages of Hodieda governorate. Methodology: Cross section study with multistage sample, Random selection of one urban and one rural locality. 768 housewives were interviewed, proportionally allocated sample according to the number of vulnerable groups in each locality. Systematic random sample to select households. Results: The use rate of LLINs for vulnerable groups was 74.3% CI (71.2 - 77.4). There was no statistically significant association between the use of LLINs and residence, also with ages of housewives, occupation, type of house, but there is strong statistically significant association between use of LLINs and having correct information about how to use and to take care of them P value < 0.001, also with educational status of housewives;P value 0.03 and educational status of fathers;P value 0.01. (84%) have correct information about how to use and take care of LLINs and the main source of information was health workers who distributed them. Only 13.4% realized pregnant women as a vulnerable group to malaria infection while about 77.9% realized children as a vulnerable group to malaria infection. The main reason of LLINs use (84.8%) was protection from nuisance of insects. Conclusion and recommendations: There is shortage in the information about the protective effect of LLINs from malaria infection and the main reason of using them is protection from nuisance of insects. There is a need to increase health awareness about the role of LLINs in malaria prevention.

Mass Distribution Campaign of Long-Lasting Insecticidal Nets in the Democratic Republic of Congo from 2018 to 2021 in the Context of the Emergence of COVID-19: Results and Lessons Learned

Introduction: The DRC had planned 23 mass distribution campaigns distribution of long-lasting insecticidal nets (LLIN) for the years 2018-2020, the implementation of which spanned from 2018 to July 2021. This article reviews the campaign’s planning process, the results, challenges, and lessons learned. Methods: A descriptive method was used to postpone the planning and implementation process according to the National Malaria Control Program (NMCP) standards adapted to the COVID-19 context. The changes and adaptations implemented as well as the challenges encountered are described. Results: Between January 2018 to June 2021, 23 LLIN mass distribution campaigns were organized in the DRC with the financial support of The Global Fund to Fight against Tuberculosis, AIDS and Malaria (GFTAM) and Against Malaria Foundation (AMF) allowing the distribution of 55,273,473 LLINs to 19,048,372 households at risk of malaria transmission with an average of 2.9 LLINs per household. The enumerated population (111,081,191) exceeded 7% of the micro plans projected population (102,790,391) while the number of households enumerated (19,311,629) was 3% lower compared to the micro planning projection households (19,862,417). Compared to a reported household coverage of 96% of households achieved over the expected households, the independent monitoring carried out revealed 91% of households served in the intervention areas. The main reasons for not reaching households mentioned by the respondents were absence at the time of distribution (26%) followed by the loss of vouchers (16%). Several communication channels were used among which, community workers were the most frequently mentioned (63.1%), followed by radios (18.5%) and churches (12.4%). Conclusion: Good planning, effective coordination of stakeholders, and revision of the implementing campaigns methods following the COVID-19 were factors in the success of this campaign. An effort to respect the schedules for renewing LLINs in households, coupled with good continuous distribution, is necessary to maintain the gains and hope for an impact in terms of morbidity and mortality reduction of malaria.

Evaluation of Efficacy of Insecticides and Long-Lasting Insecticidal Nets for Control of Culex quinquefasciatus Say Populations from Northern Nigeria

Information on Culex mosquitoes (vectors of filarial worm and viral encephalitis) from northern Nigeria is scanty, hindering evidence-based control. Here, two Culex populations (Kano and Kaduna) were characterized. Culex quinquefasciatus and Culex pipiens were found breeding in sympatry, with some hybrid individuals identified. Larval bioassays revealed high temephos resistance (LC50s = 1.34 mg/mL and 3.01 mg/mL for Kano and Kaduna, respectively). Larvae were more sensitive to α-cypermethrin (LC50s = 0.026 mg/mL and 0.067 mg/mL for Kano and Kaduna). WHO adult tube bioassays revealed high pyrethroid and DDT resistance, with mortalities of 44.01% ± 6.79%, 35.83% ± 12.58%, 29.69% ± 9.97% and 52.47% ± 4.34% for permethrin, deltamethrin, α-cypermethrin and DDT, respectively. Highest resistance was observed with bendiocarb (mortality = 13.58% ± 3.98%). High resistance was obtained with fenitrothion and malathion (mortalities = 21% ± 4.76% and 56.47% ± 8.67%, respectively), while a full susceptibility was observed with pirimiphos-methyl. Pre-exposure to piperonylbutoxide (PBO) significantly recovered α-cypermethrin susceptibility (mortality = 82% ± 5.16%, χ2 = 50.99, p < 0.0001), compared with the conventional bioassay (mortality = 32 ± 7.30). Mortalities of <20% were obtained in cone bioassays with Yorkool, DuraNet and PermaNet3.0 (side panels) nets, suggesting a loss of efficacy of conventional long-lasting insecticidal nets. However, mortalities of 99% and 86% were obtained in Kano and Kaduna populations using the roof of PermaNet3.0 (containing PBO and deltamethrin). Despite the high frequency of the 1014F VGSC knockdown resistance mutation allele (0.90), no correlation was observed between the 1014F kdr genotype and resistance phenotype. Sequencing of fragments of the acetylcholinesterase-1 gene detected no G119S mutation, in malathion-alive and malathion-dead females. These suggest a preeminent role of metabolic resistance in these Culex populations.

Field Durability of Yorkool^(█) LN Nets in the Benin Republic

Context: Recent publications on WHO recommended methods for estimating the survival of LLINs are good guidelines for assessing the performance of long-lasting insecticidal nets (LLINs). Thus, this field trial study was undertaken to evaluate the durability of the Yorkool? LN mosquito net distributed during the 2017 campaign in Benin. Methods: The monitoring of Yorkool? LN nets was carried out in two districts (Djougou III and Barienou) in Djougou, department of Donga, northern Benin from October 2017 to March 2019. A representative sample of 250 households that had received the Yorkool? LN polyester LLINs during the 2017 campaign was selected in the rural and urban areas of each district and monitored for 6, 12 and 18 months. An evaluation of the survival of Yorkool? LN nets was conducted based on the rate of loss and physical condition of the surviving nets as measured by the proportional hole index (pHI). Finally, the chemical efficacy of these LLINs during each period was determined using the WHO cone tests. Results: Survival of Yorkool? LN nets was similar in both rural and urban areas, although there was a difference in survival between the 6-month (95.3%), 12-month (89.7%), and 18-month follow-up periods (74.4%). A difference in survival was also observed between the NetCalc model (84%) compared to the Yorkool? LN nets of this study (74.4%). The attrition rate was 29.6% for LLINs at 18 months. Surprisingly, the physical integrity of the LLINs was minimally affected in the municipality. Indeed, the proportion of mosquito nets in good condition without a hole was 51.8% compared to 56.8% with a hole after 18 months. Only 7.8% of the LLINs in the two districts were damaged compared to 2.6% which needed to be replaced. The washing frequency, location of the LLINs and the frequency of use are some factors contributing to the appearance of the holes in LLINs. The bio-efficacy results of LLINs based on the cone test were good with mortality rates of 74%, 66%, 72% and 58% respectively after baseline, 6, 12 and 18 months of use. Conclusions: The observed differences in the survival of Yorkool? LN nets are due to community living conditions and movements and not to the equipment used to manufacture LLINs. However, the estimated median survival has shown that Yorkool? LN nets would have an average lifespan of 2 years 8 months despite their fairly good physical condition. These results may be useful to the National Malaria Control Program (NMCP) during the period of replacement of these nets on the field.