“House Plasmodial Prevalence Index” Another Relevant Indicator of Evaluating a Malaria Vector Control Operations, Example of Capango Village (Benguela Province, Angola)

The WHO fascicule “Information systems for the evaluation of malaria control programmes” identified as outcome target “the proportion of households targeted for use of nets using at least one impregnated bednet” [1].The parasitological evaluation of the efficacy of vector control programme is mainly based on the plasmodial prevalence rate evaluated by cross sectional or longitudinal surveys on representative sample of the human population targeted.For the new “House plasmodial” index we decided to combinethe 2 indicators: the classical human plasmodial prevalence and house considering as positive any house with “at least one symptomless inhabitant having at least one positive thick film during the survey”. We used this new indicator when analyzing data gained during 24 regularly done parasitological surveys during 5 years in Capango village where a vector control (VC) programme was implemented using both Long Lasting Nets PermaNet© 2.0 and deltamethrin treated wall lining called ZeroFly© inside every house. Surveys were done during 2 years before VC and 3 years after.It appeared that the House Plasmodial positive index showed the same trends and level as the classical human plasmodial prevalence and clearly indicated the impact of vector control in reducing the overall plasmodial prevalence in the targeted village.On the other hand it appeared repeating surveys identified “frequently positive houses” (=found positive in some 50% of surveys) and therefore to be prioritized for controland those “scarcely positive” (20% of surveys). The House Plasmodial Prevalence index appeared relevant and reliable, interesting to be used in vector control programme while easy to get and should be considered in other epidemiological situation.

Bio-efficacy, physical integrity, community usage and washing practices of mosquito nets treated with ICON MAXX long-lasting insecticidal treatment in India

BACKGROUND New brands of potential long lasting insecticide nets (LLINs) and LLIN treatment kits require field evaluation before they are used in a vector control programme. OBJECTIVES The aim of this study was to evaluate the bio-efficacy, usage, washing practice and physical integrity of nets treated with LLIN treatment kit, ICON MAXX in a phase III field trial in Odisha state, India. METHODS A total of 300 polyester nets treated with ICON MAXX and 140 polyester nets treated conventionally with lambda-cyhalothrin CS 2.5% ITNs were distributed. The bio-efficacy was evaluated with WHO cone bioassay. The chemical analysis of netting pieces was done at the beginning, after 12 and 36 months of the trial. FINDINGS After one year of distribution of nets, the bioassay showed 100% mortality on both ITNs and ICON MAXX treated nets. At 36 months, the overall pass rate was 58.8% and the mean lambda-cyhalothrin content of LLINs was 34.5 mg ai/m2, showing a loss of 44.4% of the original concentration. CONCLUSION ICON MAXX treated LLIN was found to retain bio-efficacy causing 97% knockdown of Anopheles stephensi up to 30 months and met the WHOPES criteria. However, the desired bio-efficacy was not sustained up to 36 months.

Malaria Prevalence, the Use of Intermittent Preventive Therapy and Long Lasting Insecticidal Nets among Pregnant Women in Onitsha, Anambra State, Nigeria.

Malaria prevalence, the use of intermittent preventive therapy (IPT) and long lasting insecticidal nets (LLINs) was studied among pregnant women in Onitsha, Anambra State, Nigeria. Peripheral blood were obtained from 204 pregnant women and examined microscopically for malaria parasites. Structured questionnaire was used to determine the use of IPT and LLIN among the pregnant women. The results showed an overall malaria prevalence of 40.5% (99/204) in pregnant women. Prevalence varied markedly within age groups, with ages 15-19 recording a value of 75%. Prevalence among the primigravidae was 55.1% compared to 39.5% for multigravidae. There was a statistical significance in prevalence by age and by parity (P<0.05). Compliance to the use of IPT was 53.9% (110/204). The result also showed that 79.4% (162/204) sleep under LLIN. Malaria was still a problem among pregnant woman and IPT reduced malaria during pregnancy.

Evaluation of Field Performance of Insecticide-Treated Mosquito Nets in North-Western Burkina Faso.

Aims: The aim of the study was to evaluate the field performance of insecticide-treated mosquito nets (ITNs) in north-western Burkina Faso. Study design: Cross-sectional survey. Place and Duration: The study took place between September and November 2008 (end of rainy season) in rural north-western Burkina Faso. Methodology: Standard WHO bioassays were performed on field-collected ITNs from three areas of different insecticide pressure: semi-urban Nouna town, three villages with cotton agriculture, and three villages without cotton agriculture. Data on age and washing frequency of ITNs was collected, and deltamethrin content was determind by HPLC. Results: The mean age of field-collected ITNs was 2.1 years. The mosquito mortality rate (Anopheles gambiae sl.) after 24 hours was 4% for the negative controls, 90% for the positive controls, and 73% for field-used ITNs. Differences in mosquito mortality between sub-areas disappeared after controlling for confounding variables. Conclusion: This study demonstrates that under real life conditions, deltamethrin still shows some level of effectiveness despite ongoing insecticide pressure. However, deltamethrin resistance has been observed in other parts of the country and thus close surveillance of ITN efficacy is needed. More frequent replacement of ITNs is also recommended.

Community awareness, perceptions, acceptability and preferences for using LLIN against malaria in villages of Uttar Pradesh, India.

Background & Objectives: Long-lasting insecticidal nets (LLINs) have been introduced in India recently into the vector control programme. A study was undertaken to assess the community perception regarding use of LLIN, their acceptability, collateral benefits, etc. in certain villages of District Gautam Budh Nagar, Uttar Pradesh, India where LLINs are in use by the community. Method: A randomized community-based survey was undertaken during April–May 2009 covering 596 respondents in LLIN villages where LLINs have been distributed along with 307 respondents in untreated net villages where untreated nets were distributed using structured questionnaire. Qualitative data were collected and the difference in proportion was calculated by z-test. Results: A substantial number of respondents had good knowledge of the symptoms of malaria. According to respondents, LLINs were very much effective in bringing down the malaria incidence in their families. About 98.3% of the respondents asserted the use of LLINs as their use not only reduced the number of mosquitoes as well as other non-target insects, but also reduced the malaria incidence. About 93.2% of the respondents were ready to purchase LLINs if available at nominal prices. All the respondents were satisfied about the performance of the LLINs in reducing the mosquito nuisance, safety of use and collateral benefits in LLIN villages. Conclusion: LLINs are safe, socially acceptable and should be promoted for vector control to reduce the disease burden in the communities.