Field evaluation of Icon®Life, a long-lasting insecticidal net (LLIN) against Anopheles culicifacies and transmission of malaria in District Gautam Budh Nagar (Uttar Pradesh), India.

BACKGROUND & OBJECTIVES: In the present study, Icon®Life net, a long-lasting polyethylene net, 100 denier and bursting strength of minimum 280 kpa incorporated with deltamethrin @ 65 mg/m2 was evaluated for its efficacy in reducing the density of malaria vector Anopheles culicifacies and impact on malaria prevalence in a malaria endemic area of District Gautam Budh Nagar, India. METHODS: Wash resistance of Icon®Life LLIN was determined up to 20 serial washings using An. culicifacies in cone bioassays under field conditions. Efficacy of Icon®Life LLIN was determined in the field in three sets of villages in District Gautam Budh Nagar (Uttar Pradesh), India, selected randomly for the intervention with Icon®Life LLIN, untreated nets and a control without any intervention for the period of August 2008-July 2009. Entomological and malariometric indices in all the three villages were compared during pre- and post-intervention periods for one year against An. culicifacies. A survey was also conducted in the village provided with Icon®Life LLIN to assessing the perception of community regarding acceptance of these nets by the community. RESULTS: In cone bioassays on Icon®Life LLIN with An. culicifacies, >95% knockdown within 1 h and 100% mortality after 24 h exposure were reported even after 20× serial washings under field conditions. Results of the field study revealed reduced entry rate, resting density and parity rate of An. culicifacies in the village with Icon®Life LLIN when compared to no net and untreated net villages. Number of malaria cases reported were less in the Icon®Life LLIN used villages when compared to other two villages. The community compliance and acceptance was high and no adverse health events were reported by the households using these nets. CONCLUSIONS: Icon®Life LLIN is an effective intervention for the control of An. culicifacies transmitted malaria in India. Long-term studies are indicated for the duration of effectiveness and to ascertain the epidemiological impact of the use of Icon®Life nets.

Insecticide susceptibility status of Phlebotomus argentipes, a vector of visceral leishmaniasis in different foci in three states of India.

BACKGROUND & OBJECTIVES: Phlebotomus argentipes is the vector for visceral leishmaniasis in India. The development of resistance in kala-azar vector to DDT has been reported from various parts of India. The main objective of this study was to generate information on insecticides susceptibility status of P. argentipes to DDT, malathion and deltamethrin in different parts in three states of India. METHODS: Phlebotomus argentipes were collected from different villages, identified and used to investigate the susceptibility status against DDT, malathion and deltamethrin as per the WHO standard methods. RESULTS: Phlebotomus argentipes was resistant to DDT in different areas, viz. PHCs Murumgaon in Maharashtra; Ramgarh in Jharkhand; Kodah, Falka, Mahua and Lalganj in Bihar. In Phulwari Shareef PHC of Patna district in Bihar, DDT produced 89% mortality in P. argentipes, indicating resistant/tolerance (verification required) to DDT. The corrected percent mortality to malathion (5%) in different areas ranged between 98 and 100%; and to deltamethrin (0.05%) between 98.4 and 100%. The results showed that the tested P. argentipes are susceptible to malathion and deltamethrin. CONCLUSION: Phlebotomus argentipes are still susceptible to malathion and deltamethrin, but resistant to DDT. The susceptibility status of P. argentipes should be monitored regularly in diversified situations to ascertain the judicious use of insecticides being used for indoor residual spraying in the programme for rational use of appropriate insecticide.

Evaluation of indoor residual spray and insecticide treated bed nets in a malaria endemic area of Santhal Pargana, Dumka district (Jharkhand).

The study was carried out for evaluation of various activities of malaria control programme in five different tribal and malaria endemic Primary Health Centres of Dumka district (Jharkhand) during 2007-08. A total of 321 houses of 18 villages were surveyed on use of indoor residual spray (IRS) and insecticide-treated bed nets (ITN) and other activities as tool for vector control and interrupting the transmission of malaria. Out of 690 living rooms and 343 verandahs examined, IRS with Dichlorodiphenyl-trichloro-ethane (DDT) was done only in 16.23% living rooms and 64.72% verandahs. Refusal rate of IRS in living rooms was 81.93% due to lack of knowledge regarding the importance of IRS, no prior information to villagers, houses locked, reluctance to remove domestic articles, dislike of smell of DDT spray. Compliance rate of ITN uses was 71.66% during the night, which might be a factor for decline in malaria cases in the study area. Various important components of the programme, viz. surveillance and compliance to treatment activities, use of rapid diagnostic test kits (RDKs), involvement of accredited social health activist (ASHA's) and fever treatment depots (FTDs), laboratory activities, adult mosquito collection, other activities like constitution of village health sanitation committee, information education and communication activities, capacity building, use of larvivorous fishes, supervision of IRS etc. require much strengthening. However, 100% community acceptance was recorded for ITN in the villages surveyed. In addition, an entomological study was carried out for information on prevalence of mosquito species in this area to find out effectiveness of IRS activities. Eleven anopheline species, including three malaria vectors i.e., An. culicifacies, An. stephensi, An. fluviatilis, An. annularis, An. subpictus, An. nigerrimus, An. pallidus, An. aconitus, An. vagus, An. jamsii and An. splendidus were collected from cattle and human dwellings.

Evaluation of the impact of ZeroFly®, an insecticide incorporated plastic sheeting on malaria incidence in two temporary labour shelters in India.

BACKGROUND & OBJECTIVES: Prevention of malaria is a major technical and operational problem in displaced and mobile populations such as refugee camps and temporary labour settlements. Insecticide incorporated plastic sheeting is a new technology to control mosquitoes in emergency shelters and also temporary habitations at different locations. In view of this, efficacy of ZeroFly® , an insecticide incorporated plastic sheeting (factory treated with deltamethrin 2.0 g/kg or 265 mg/m2 ) was evaluated for its efficacy against malaria vectors and its impact on malaria incidence in temporary labour settlements in two urban areas in India. METHODS: This trial was conducted in two labour settlements in two urban areas, Delhi and Noida (U.P.), India with ~ 250 populations. In an area, two localities were selected for intervention with ZeroFly and untreated plastic sheets (control). Entomological and epidemiological data were collected using standard methods for one year. RESULTS: Baseline studies on the susceptibility of mosquitoes in Delhi and Noida areas revealed 100% susceptibility of the malaria vector species Anopheles culicifacies and An. stephensi to deltamethrin. Cone bioassay tests performed against An. culicifacies and An. stephensi to determine the efficacy of ZeroFly sheets showed 100% mortality against An. culicifacies and An. stephensi with 3 min exposure and after 24 h recovery period. Against Culex quinquefasciatus and housefly 100% mortality was obtained after 30 min of exposure period. Intervention with the ZeroFly plastic sheets resulted in almost complete reduction in the resting density of An. culicifacies and An. stephensi, the two major malaria vectors and also in the reduction of malaria cases in ZeroFly camps as compared to control camps. The ZeroFly plastic sheeting was found to be safe for human. Barring some complaints of skin irritation and itching, which were temporary in nature, no adverse health effects were reported by the users. The community acceptance was high. CONCLUSION: Results of the present study revealed that ZeroFly® plastic sheeting is highly effective in reducing the indoor resting density of mosquitoes, man -vector contact and malaria incidences in labour populations living in temporary shelters.

Efficacy of Advanced Odomos repellent cream (N, N-diethyl-benzamide) against mosquito vectors.

BACKGROUND & OBJECTIVES: Repellents are commonly used personal protection measures to avoid mosquito bites. In the present study, Advanced Odomos cream (12% N, N-diethyl-benzamide) was tested for its efficacy against mosquitoes in comparison to DEET (N,N-diethyl-3-methyl benzamide). METHODS: Bioassays were conducted to assess the repellency of Advanced Odomos and DEET creams against Anopheles stephensi and Aedes aegypti. Their efficacy was tested on human volunteers applied with different concentrations of test creams ranging from 1 to 12 mg/cm 2 and by exposing them to mosquitoes at hourly intervals. Field evaluation was also carried out to test the duration of protection of the test creams against Anopheles and Aedes mosquitoes during whole night and day time collections, respectively on human volunteers. Mosquito collections were done using torch light and aspirator. RESULTS: Complete (100%) protection was achieved at 10 mg/cm 2 cream formulation of Advanced Odomos (1.2 mg a.i/cm 2 ) dose against An. stephensi and 12 mg/cm 2 (1.44 mg a.i./cm 2 ) against Ae. aegypti on human baits. There was no statistically significant differences in per cent protection against mosquito bites between Advanced Odomos and DEET cream (P>0.05) in respective doses. Complete protection up to 11 h was observed against Anopheles mosquitoes during whole night collections and up to 6 h against Ae. aegypti in day time collections. No adverse reactions such as itching, irritation, vomiting, nausea, etc. were reported by the volunteers. INTERPRETATION & CONCLUSIONS: Advanced Odomos cream applied at 10 mg/cm 2 concentration provided 100% protection from Anopheles mosquitoes up to 11 h whereas about 6 h protection was recorded against Ae. aegypti. The laboratory and field trials indicate that for longer protection against Anopheles mosquitoes 10 mg/cm 2 will be appropriate and in case of Ae. aegypti more than 10 mg/cm 2 application is required for complete protection. In conclusion, the Advanced Odomos cream was comparable to the known repellent cream DEET for prolonged protection against malaria and dengue vectors.

Wash resistance and efficacy of Olyset net and Permanet 2.0 against Anopheles stephensi in India.

Long-lasting insecticidal nets (LLIN) have been developed for wash resistance and long-lasting effects against mosquito vectors. In this study we evaluated 2 LLIN products, Olyset net and Permanet 2.0, washed for 0, 5, 10, 15, and 20 times, against Anopheles stephensi, an urban malaria vector in India. We assessed the wash resistance and efficacy of these nets in relation to bloodfeeding inhibition and percent mortality in cone and tunnel test bioassays. Both Olyset and Permanet showed >80% mortality of An. stephensi in cone bioassays after 20 washes. In tunnel tests there was no significant difference between Olyset and Permanet 2.0 in causing total mosquito mortality (immediate and delayed) up to 10 washes and bloodfeeding inhibition and entry rate up to 15 washes. After the 20th wash, Permanet 2.0 was significantly more effective than the Olyset net in causing total mosquito mortality, whereas Olyset net showed less bloodfeeding and entry of mosquitoes as compared to Permanet 2.0. There was a gradual decline in efficacy of both LLIN products as the number of washings increased. Cone bioassays indicated a strong wash resistance in both the LLIN products after 20 washes. However, the tunnel tests demonstrated a gradual decline in efficacy of both products with the number of washings.

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.

Field evaluation of ZeroFly--an insecticide incorporated plastic sheeting against malaria vectors & its impact on malaria transmission in tribal area of northern Orissa.

BACKGROUND & OBJECTIVES: Insecticide incorporated plastic sheeting is a new technology to control mosquitoes in emergency shelter places and also temporary habitations in different locations. Therefore, field studies were conducted to assess the efficacy of ZeroFly plastic sheeting treated with deltamethrin on prevailing disease vectors Anopheles culicifacies and An. fluviatilis and its impact on malaria transmission in one of the highly endemic areas of Orissa. METHODS: The study was conducted in Birkera block of Sundargarh district, Orissa state. The study area comprised 3 villages, which were randomized as ZeroFly plastic sheet, untreated plastic sheet and no sheet area. ZeroFly plastic sheets and untreated plastic sheets were fixed in study and control villages respectively covering all the rooms in each household. Longitudinal studies were conducted on the bioefficacy with the help of cone bioassays, monitoring of the mosquito density through hand catch, floor sheet and exit trap collections and fortnightly domiciliary active surveillance in all the study villages. RESULTS: In ZeroFly plastic sheeting area, there was a significant reduction of 84.7 per cent in the entry rate of total mosquitoes in comparison to pre-intervention phase. There was 56.2 per cent immediate mortality in total mosquitoes in houses with ZeroFly sheeting. The overall feeding success rate of mosquitoes in the trial village was only 12.5 per cent in comparison to 49.7 and 51.1 per cent in villages with untreated plastic sheet and no sheet respectively. There was a significant reduction of 65.0 and 70.5 per cent in malaria incidence in ZeroFly plastic sheeting area as compared to untreated plastic sheet and no sheet area respectively. INTERPRETATION & CONCLUSIONS: Our study showed that introduction of ZeroFly plastic sheets in a community-based intervention programme is operationally feasible to contain malaria especially in the high transmission difficult areas.

Effect of synergist piperonyl butoxide (PBO) on the toxicity of some essential oils against mosquito larvae.

Effect of a known synergist piperonyl butoxide on the toxicity of steam distillate essential oils of Jamarosa (Cymbopogan nardus), Pacholli (Pogostemon pacholli), Basil (Ocimum basilicum), and Peppermint (Mentha pipreta) plant species against Anopheles stephensi larvae were evaluated. The purpose of the present study was to identify the insecticidal potential of these oils against mosquito larvae. The Piperonyl Butoxide (PBO) was used to enhance the activity of these oils with the aim of developing essential oil based formulations. The bioassays of these oils with and without PBO were performed against late 3rd instar larvae of An. stephensi. The LC50 values against An. stephensi were 44.19 ppm for Ocimum basilicum oil, followed by, Mentha pipreta, Cymbopogan nardus, and Pogostemon pacholli oil which gave LC50 values above 250 ppm. Thus in the present study the Ocimum basilicum oil was found to be most effective, whereas Pogostemon pacholli oil was found to least effective against mosquitoes for larvicidal action. The effect of synergist PBO led to the enhancement of toxicity of oils, the LC50 value for Ocimum basilicum were reduced from 44.19 ppm to 23.87 ppm. Similarly the oil of Pogostemon pacholli showed most significant results where the LC50 value was > 250 ppm it was reduced to 50 ppm with PBO.

Impact of etofenprox (Vectron 20 WP) indoor residual spray on malaria transmission.

BACKGROUND & OBJECTIVE: A longitudinal study was carried out to assess the impact of indoor residual spray with Vectron 20 WP (etofenprox) against Anopheles culicifacies and on malaria transmission in a selected village of Dadri primary health centre (PHC), District Gautam Budh Nagar, Uttar Pradesh, India. METHODS: Two villages, namely Patadi and Anandpur in District Gautam Budh Nagar, Uttar Pradesh, with similar malaria incidence and vector prevalence were selected for the present evaluation. In one village two rounds of indoor spraying of etofenprox (0.1 g/m(2)) were done at an interval of 12 wk and the other village was kept as control where no intervention except intensive active surveillance for early detection and prompt treatment (EDPT) was undertaken during the study period. Entomological and epidemiological data were collected using standard procedures. RESULTS: Persistence of the effectiveness of etofenprox against An. culicifacies was observed up to 12 wk. Spraying of etofenprox significantly reduced the density (P<0.001) and proportion of parous An. culicifacies mosquitoes (P<0.05) in the experimental village. There was a significant reduction in malaria cases in the experimental village during the post-spray period when compared to the control village (P<0.05). No adverse effect was reported by the spraymen and inhabitants during and after the spray. INTERPRETATION & CONCLUSION: Indoor residual spray of etofenprox (0.1 g/m(2)) with an interval of three months in between two rounds of spray produced the desired impact in reducing the indoor resting density of vector mosquitoes and also in curtailing malaria transmission in the sprayed village when compared with the control village without spray.

Effect of synergist piperonyl butoxide (PBO) on the toxicity of some essential oils against mosquito larvae.

Effect of a known synergist piperonyl butoxide on the toxicity of steam distillate essential oils of Jamarosa (Cymbopogan nardus), Pacholli (Pogostemon pacholli), Basil (Ocimum basilicum), and Peppermint (Mentha pipreta) plant species against Anopheles stephensi larvae were evaluated. The purpose of the present study was to identify the insecticidal potential of these oils against mosquito larvae. The Piperonyl Butoxide (PBO) was used to enhance the activity of these oils with the aim of developing essential oil based formulations. The bioassays of these oils with and without PBO were performed against late 3rd instar larvae of An. stephensi. The LC50 values against An. stephensi were 44.19 ppm for Ocimum basilicum oil, followed by, Mentha pipreta, Cymbopogan nardus, and Pogostemon pacholli oil which gave LC50 values above 250 ppm. Thus in the present study the Ocimum basilicum oil was found to be most effective, whereas Pogostemon pacholli oil was found to least effective against mosquitoes for larvicidal action. The effect of synergist PBO led to the enhancement of toxicity of oils, the LC50 value for Ocimum basilicum were reduced from 44.19 ppm to 23.87 ppm. Similarly the oil of Pogostemon pacholli showed most significant results where the LC50 value was >250 ppm it was reduced to 50 ppm with PBO.

Efficacy of PermaNet 2.0 against Anopheles culicifacies and Anopheles stephensi, malaria vectors in India.

Bioefficacy of PermaNet was evaluated in both the laboratory and field against Anopheles culicifacies and An. stephensi, major malaria vectors in India. Contact bioassays were carried out after repeated washings and ring net bioassays to determine the median knockdown time of mosquitoes. Three villages were selected for the field trial: in the 1st village PermaNets were distributed, in the 2nd village untreated nets were distributed, and the 3rd village was a control. Entomological data were collected using standard procedures. The PermaNet contact bioassays showed high mortality (>80%) even after 20 washes against both the vector species. The median knockdown time of An. culicifacies and An. stephensi was 392 and 480 sec when exposed to fresh PermaNets and 472 and 986 sec when exposed to PermaNets that had been washed 20 times, respectively. PermaNets showed high efficacy in reducing the person-vector contact as evidenced by reduced person-hour density in the PermaNet village. Long-term field trials are indicated to test the impact of use of PermaNets in controlling malaria.

Chemical composition and larvicidal activities of the essential oil of Zanthoxylum armatum DC (Rutaceae) against three mosquito vectors.

BACKGROUND & OBJECTIVES: In view of the recently increased interest in developing plant origin insecticides as an alternative to chemical insecticide, this study was undertaken to assess the larvicidal potential of the essential oil from the seeds of Zanthoxylum armatum DC [syn. Z. alatum Roxb] (Rutaceae) against three medically important species of mosquito vectors, Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus. METHODS: Essential oil was hydro distilled in the laboratory from the seeds obtained from the market and the chemical constituents of the oil were determined using GC/GC-MS. Bioefficacy of the essential oil was evaluated under laboratory conditions using III instar mosquito larvae. RESULTS: Among the three mosquito species tested, Cx. quinquefasciatus was the most sensitive (LC50 = 49 ppm) followed by Ae. aegypti (LC50 = 54 ppm) and An. stephensi (LC50 = 58 ppm). GC-MS analysis of the oil revealed at least 28 compounds, consisting mainly of oxygenated monoterpenes (75%) and monoterpenes (22%). Linalool though constituted a major part (57%), failed to produce any appreciable mortality when tested alone. INTERPRETATION & CONCLUSION: From the results it can be concluded that the larvae of the three mosquito species were susceptible to the essential oil composition. Such findings would be useful in promoting research aiming at the development of new agent for mosquito control based on bioactive chemical compounds from indigenous plant sources as an alternative to chemical larvicides.

Impact of Olyset nets on malaria transmission in India.

BACKGROUND & OBJECTIVES: Efficacy of Olyset nets, long-lasting insecticidal nets were tested from August 2003 to August 2006 against Anopheles culicifacies, the vector which transmits 60% of all malaria cases in rural India. METHODS: Three villages in District Gautam Budh Nagar (Uttar Pradesh), India were selected for the trial and Olyset nets were distributed in one village, in another village untreated nets were distributed and the third village was kept as control where nets were not used. Entomological, and epidemiological data were collected using standard methods. RESULTS: The use of Olyset nets reduced the indoor resting density of An. culicifacies and also reduced mosquito entry into the structures where Olyset nets were used. No mosquitoes were caught landing on the Olyset nets. There was a reduction in the parity rate of An. culicifacies in the Olyset net village as compared with untreated net and no net villages. The impact of Olyset nets was observed on malaria incidence and only one case of Plasmodiumfalciparum malaria was reported in the Olyset net village but these continued to be found in the village with untreated nets and the control. CONCLUSION: Results of the present study confirmed that Olyset nets are highly effective in reducing the indoor resting density of mosquitoes, man-vector contact and malaria incidence.