Impact of urbanization on the abundance and distribution of Anophelines population in Ghaziabad district, Uttar Pradesh, India.

BACKGROUND OBJECTIVES: In urban areas, upsurge in population has resulted in more breeding sites for malaria vectors, and hence this scenario potentially undermine malaria elimination and control programs. The change in land use due to urbanization may result in the presence and distribution of malaria vectors. Understanding potential malaria vectors is essential for current and future malaria transmission control strategies. This study investigated the effects of rapid urbanization on malaria vectors An. culicifacies s.l. and An. stephensi L. in Ghaziabad district. METHODS: Ghaziabad district which presents several levels of urbanization was selected for this study. Entomological investigations were conducted seasonally from 2014-2016 in the rural, urban, and peri-urban regions. Vector incrimination study was done using ELISA (confirmation by PCR) on suspected Anopheles vectors viz. An. culicifacies, An. stephensi, An. annularis and An. subpictus. RESULTS: An. culicifacies showed alteration in distribution influenced by rural and agricultural land whereas An. stephensi was found to be influenced by artificial habitats and population growth. INTERPRETATION CONCLUSION: The study also confirms the association between the abundance of malaria vectors and land use change.

Novel development of Lecanicillium lecanii-based granules as a platform against malarial vector Anopheles culicifacies.

Mosquitoes are infectious vectors for a wide range of pathogens and parasites thereby transmitting several diseases including malaria, dengue, Zika, Japanese encephalitis and chikungunya which pose a major public health concern. Mostly synthetic insecticides are usually applied as a primary control strategy to manage vector-borne diseases. However excessive and non-judicious usage of such chemically derived insecticides has led to serious environmental and health issues owing to their biomagnification ability and increased toxicity towards non-target organisms. In this context, many such bioactive compounds originating from entomopathogenic microbes serve as an alternative strategy and environmentally benign tool for vector control. In the present paper, the entomopathogenic fungus, Lecanicillium lecanii (LL) was processed to make the granules. Developed 4% LL granules have been characterized using the technique of Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). The developed formulation was also subjected to an accelerated temperature study at 40 °C and was found to be stable for 3 months. Further, GCMS of the L. lecanii was also performed to screen the potential biomolecules present. The developed formulation was found to be lethal against Anopheles culicifacies with an LC50 value of 11.836 µg/mL. The findings from SEM and histopathology also substantiated the mortality effects. Further, the SEM EDX (energy dispersive X-ray) studies revealed that the treated larvae have lower nitrogen content which is correlated to a lower level of chitin whereas the control ones has higher chitin content and healthy membranes. The developed LL granule formulation exhibited high toxicity against Anopheles mosquitoes. The granule formulations can be used as an effective biocontrol strategy against malaria-causing mosquitoes.

Sustainable control of malaria employing Gambusia fishes as biological control in Jalore and Barmer districts of Western Rajasthan.

Sardar Sarovar Irrigation Canal system was constructed by Narmada Valley Development Authority (NVDA) to cater to drinking water as well as for irrigation purposes in Jalore and Barmer districts of Western Rajasthan. To cater to the needs of water for the villagers in the command areas, 'Diggies' (surface water tanks) with 'Sumpwells' (water supply surface tanks) were installed. In a health impact assessment study of the irrigation canals from December 2010 to February 2016, the breeding of two major malaria vectors. An. culicifacies and An. stephensi were observed in diggies and sumpwells. As a biological control, Gambusia affanis fishes were employed for larval control in such stagnated water sites during the intervention phase viz. February 2012 in 251 diggies and 251 sumpwells. A significant reduction of breeding in diggies (99.54%) and sumpwells (97.81%) was observed. The positivity and larval density (dip index) were monitored in the control from up to February 2016 for their sustainability.

Mobile app based pictorial identification key for Indian anophelines.

BACKGROUND & OBJECTIVES: Malaria control strategies for a particular area largely depends on the correct identification of the mosquito species prevalent in that area. This study aimed to develop an android mobile app named 'Pictorial Indian anophelines key', which can be used to identify the 58 species of Indian female adult anophelines based on morphological characteristics. METHODS: The pre-requisite to use this app requires a minimum basic knowledge of mosquito morphological characteristics and features. The user needs to view the collected mosquito under a dissecting binocular microscope and has to select the observations on the app presented in the form of labelled picture format. The app uses a divide and conquer algorithm which narrows the selection from genus level to final identification of species. RESULTS: The app is user-friendly, quick and it accurately identifies the mosquito species in a maximum of six consecutive clicks. The result displays a complete image of identified mosquito along with its quick identification features. It can be used for both subgenus Cellia and Anopheles. INTERPRETATION & CONCLUSION: This pictorial key-based mobile app could be helpful for entomologists, malariologists, researchers, public health workers as well as students in the quick and correct identification of anopheline mosquitoes prevalent in India which in turn could be helpful in devising appropriate approaches towards malaria control and prevention. The app can be modified as per future requirements.

Co-distribution of dengue and Chikungunya viruses in Aedes mosquitoes of Delhi, India.

BACKGROUND & OBJECTIVES: In India, vector-borne diseases, dengue and chikungunya are major public health concerns. In recent decades, dengue outbreaks have been reported in almost every part of India. In 2016, India recorded 101388 dengue cases and 210 deaths, including 4337 cases and six deaths in Delhi, whereas Chikungunya outbreaks were reported from several states in 2006, with 1.3 million cases. The Dengue virus (DENV) and Chikungunya virus (CHIKV) are both transmitted by the same Aedes mosquito species. DENV and CHIKV co-infections have been reported in 13 of 98 countries, with both viruses being transmitted locally. The reasons for the sudden upsurge in cases of these diseases are undetermined. METHODS: From March to December 2016, a study was carried out in 66 localities of Delhi in collaboration with the Municipal Corporation of Delhi. Localities were selected on the basis of confirmed dengue cases reported during the last five years and the study area was visited once a month. A door-to-door entomological survey was conducted to identify Aedes breeding in all water-filled containers in and around houses. Both immature and mature stages of Aedes mosquitoes were collected. Mosquitoes were pooled (n≤10 each for male and female) breeding site-wise and stored in Trizol at -80°C. The Chikungunya and dengue viruses were detected using a multiplex RT-PCR. RESULTS: A total of 981 Aedes mosquitos were distributed among 146 Pools, and DENV and CHIKV were detected using Multiplex Reverse Transcriptase-PCR. Chikungunya virus was identified in 19 pools of females captured adults, whereas dengue virus was found in 8 pools of females captured adults. There was no evidence of coinfection in any of the pools. INTERPRETATION & CONCLUSION: In endemic areas, continuous surveillance for both dengue and Chikungunya viruses is required to identify and characterize these viral pathogens. This information will also help implement effective strategies to combat outbreaks produced by these emerging viral pathogens.

Larvicidal activity of Ricinus communis extract against mosquitoes.

BACKGROUND & OBJECTIVES: Vector control strategies play significant role in reducing the transmission of malaria, dengue and other vector-borne diseases. The control of vector population using synthetic insecticides has resulted in development of insecticide resistance and negative effects on humans and environment. The present investigation evaluated the larvicidal potential of methanol, dichloromethane and hexane extracts of leaves and seeds of Ricinus communis (castor) plant against the early IV instar larvae of the dengue vector, Aedes aegypti, and malaria vector, Anopheles culicifacies. METHODS: Plant extracts were screened for their efficacy against Ae. aegypti and An. culicifacies using WHO standard larval susceptibility test method. Dose response bioassay was performed to get lethal concentrations. Further, gas chromatography-mass spectroscopy (GC-MS) analysis was carried out to identify the bioactive chemical constituents of the extracts of R. communis. Toxicity of the extracts towards non-target organism, Poecilia reticulata was also evaluated. RESULTS: The leaf and seed extracts of R. communis showed significant mortality against the larvae of Ae. aegypti and An. culicifacies at concentrations of 31.25, 62.5, 125, 250, 500 ppm; and 2, 4, 8, 16, 32, 64 ppm, respectively. At 24 h of the exposure period, the larvicidal activities were highest for the methanol extract of seeds with LC50 15.52 and 9.37 ppm and LC90 45.24 and 31.1 ppm for Ae. aegypti and An. culicifacies, respectively. The methanol extract of seeds and leaves was found to be safe towards non-target organism, P. reticulata. The GC-MS profile showed that seed extracts were having higher concentration of stigmasterol (7.5%), ß-sitosterol (11.48%), methyl linoleate (2.5%), vitamin E (11.93%), and ricinoleic acid (34%) than the leaf extracts. INTERPRETATION & CONCLUSION: The seed extract of R. communis has better larvicidal activity than the leaf extract and can be used as an effective larvicide against mosquitoes. The non-toxicity of the extracts towards P. reticulata further suggests that these plant extracts could be used along with predatory fishes in integrated vector control approaches.

Health Impact Assessment of Indira Sagar Project: a paramount to studies on Water Development Projects.

BACKGROUND: Very limited studies on Health Impact Assessment (HIA) of Water Development Projects (WDP) in relation to mosquito-borne diseases have been carried out in India. The current study focuses on using HIA as a tool for finding impact of Indira Sagar Project, Madhya Pradesh on human health in relation to mosquito borne diseases, and emphasizing its incorporation as an integral part of any WDP. METHODS: Screening, scoping, assessment, recommendation, reporting, and evaluation were carried out in selected study areas. Entomological, epidemiological, socio-economic and knowledge, attitudes and practices data related to malaria transmission in three dam components: Submergence (SUB), Command (CMD) and Resettlement and Rehabilitation (RR) colonies were generated for the period of January 2013-December 2014. Statistical analysis was attempted to compare data among dam components and to identify risk factors. Component-specific mitigation measures were suggested based on observations. RESULTS: Anopheles culicifacies was the dominating species in all three dam components and its man-hour density in CMD areas was higher compared to SUB and RR. The odds of finding a positive malaria case was much higher in CMD compared to SUB (OR 1.24, CI 95% 0.71-2.43) and RR (OR 5.48, CI 95% 0.73-40.63). Respondents of CMD stated more previous episodes of malaria (81.8%) compared to RR (61.4%) and SUB (55.7%). The canonical discriminant analysis concluded that distance from reservoir/Indira Sagar canal had the highest discriminating ability of malaria cases in different components followed by treatment-seeking behaviour and malaria history. The analysis identified these risk factors with 70% accuracy. CONCLUSION: Engineering manipulations may be carried out in CMD areas to control seepage and RR colonies should be established beyond 3 km from reservoir/Indira Sagar canal considering the flight range of A. culicifacies. Strengthening of surveillance with early detection and complete treatment was recommended for CMD areas. To avoid future transmission in other areas and projects HIA should be carried out at planning stage for planning better control activities.

Role of An. culicifacies as a vector of malaria in changing ecological scenario of Northeastern states of India.

BACKGROUND & OBJECTIVES: Malaria has become endemic and subject of concern in most part of the India especially Northeastern states of India. Surveys before 2000 revealed that Anopheles minimus was major vector responsible for transmission of malaria in this region followed by An. dirus and An. fluviatilis. However, recent studies indicate replacement of An. minimus vector by An. culicifacies due to different ecological changes and change in landuse pattern etc. The objective of present study was to explore the vectorial role of An. culicifacies in transmission of malaria in four malaria endemic states, viz. Assam, Meghalaya, Manipur and Sikkim of India. METHODS: The seven surveys were conducted in 176 selected villages belonging to eight districts of the four states in both pre-monsoon (March-April) and post-monsoon (September-October) seasons from 2010 to 2013. However, in 2011 surveys could not be carried out due to public inconvenience in pre-monsoon season. For vectorial role of all vector species collected, ELISA and PCR were assayed. RESULTS: A total of 19,173 specimens belonging to 30 anopheline species were collected, out of which 4315 belonged to four established vector species. In total, 4183 specimens were processed through ELISA, out of which 236 specimens were found positive for circumsporozoite (CS) protein. Further, infectivity was confirmed by PCR in 35 samples, of which 12 samples were found positive for Plasmodium falciparum and three for P. vivax. Out of 12 Plasmodium falciparum positive samples, nine samples were positive for An. culicifacies, two for An. fluviatilis and one for An. minimus. While out of three Plasmodium vivax positive samples, two samples were positive for An. dirus and one sample was positive for An. culicifacies. INTERPRETATION & CONCLUSION: Anopheles culicifacies replaced the An. minimus, the vector of malaria in Northeastern states of India, as it was found to be highly infected with malaria parasite as compared to An. minimus by ELISA and PCR analysis, and thus playing a major role in malaria transmission in this region. The ecological changes like deforestation, development of irrigation channels and change in landuse pattern, have helped in evolution of An. culicifacies in the study area. Therefore, modified vector control strategies are required on urgent basis.

The footprints of relapsing malaria in southwest Delhi, India.

BACKGROUND & OBJECTIVES: Control of vivax malaria is challenging due to persistence of hypnozoites causing relapses and safety concerns with primaquine in G6PD deficient individuals. We present the epidemiology of malaria with emphasis on recurrence of vivax malaria over a period of four years in southwest Delhi among patients reporting to malaria clinic. METHODS: Microscopic examination of stained blood smears of fever patients attending malaria clinic was performed. Confirmed malaria cases were treated as per the national treatment guidelines. The epidemiological data of confirmed malaria cases including demographic characteristics, age, gender and past history of malaria were analysed. Patients were asked to report in case of occurence of fever. RESULTS: From January 2011 to December 2014, 429 Plasmodium vivax, 24 P. falciparum and three mixed infection cases were reported to the Malaria Clinic at National Institute of Malaria Research, New Delhi. Malaria cases peaked in the months of August and September during all the four years. Recurrent episodes of vivax malaria were observed in 14.72% patients to whom primaquine was not dispensed, while the prevalence was 4.02% among those who received primaquine. The relapsing patterns observed were of both short as well as long latency P. vivax phenotypes. The entomological survey of area from where malaria patients reported, showed prevalence of Anopheles stephensi. INTERPRETATION & CONCLUSION: The study showed presence of persistent P. vivax malaria with strains causing both frequent and long latency recurrences (probable relapses) in southwest Delhi. This highlights the need to evaluate primaquine regimens against both these strains and formulate strategies to improve compliance to 14-days primaquine treatment.

Detection of dengue virus in individual Aedes aegypti mosquitoes in Delhi, India.

BACKGROUND & OBJECTIVES: Delhi, the capital city of India, has so far witnessed several outbreaks of dengue fever since 1967 (last one reported in 2013). Improved virological and entomological surveillance are the only tools that can help in prevention of dengue as well as in the development of dengue control programmes. The aim of the study was to conduct a prospective field study to detect dengue virus in adult Aedes aegypti mosquitoes collected from various localities represented by different socioeconomic groups in Delhi. METHODS: The study areas were selected and categorized into high, medium and low income groups on the basis of socioeconomical characteristics of the resident population, where dengue cases were reported during the past three years by MCD. Dengue viral infection was detected in the head squash of each adult mosquito by immunofluorescent assay (IFA) employing monoclonal antibodies against dengue virus (DENV). A total of 2408 females and 1206 males of Ae. aegypti were collected and tested by IFA. RESULTS: Out of 2408 Ae. aegypti females, 14 were found positive, with minimum infection rate (MIR) of 5.8 per 1000 mosquitoes. Among the 18 study areas, 11 localities were found positive for dengue virus infection. Low income group (LIG) areas showed highest mosquito infectivity (9.8), followed by medium income group (MIG), i.e. 6.2; while least was observed in high income group (HIG), i.e. 1.3. No vertical transmission of dengue virus could be detected in 1206 Ae. aegypti males collected. INTERPRETATION & CONCLUSION: The study concludes that there was high MIR in the identified localities of low and medium income groups. Estimation of MIR in a female Aedes mosquito in the existing arsenals for dengue surveillance would be an added advantage for early warning of dengue outbreak. The presence of infected mosquitoes in identified localities of Delhi was alarming and require rigorous vector surveillance so that the severe outbreaks can be prevented.

Control of Aedes aegypti and Ae. albopictus, the vectors of dengue and chikungunya, by using pheromone C21 with an insect growth regulator: Results of multicentric trials from 2007-12 in India.

BACKGROUND & OBJECTIVES: Aedes mosquito control has gained much importance nowadays in view of rise in number of reported cases of dengue and chikungunya in India and other countries. In the present study, C21 attracticide (containing a pheromone and an insect growth regulator­IGR, developed by Defence Research and Development Establishment (DRDE), Gwalior, India was tested for its feasibility for surveillance and control of Aedes mosquito in a multicentric mode from October 2007 to June 2012 in urban (Delhi, and Bengaluru district, Karnataka) and suburban (Alappuzha district, Kerala) settings of the country in three phases. METHODS: Across the randomly selected households in each study area, two to four containers treated with attracticide (experimental) and untreated (control) were placed and monitored by trained surveillance workers on weekly/ fortnightly basis for determining the presence of eggs, larvae and pupae. Container positivity, percent larvae, egg and pupae collected were determined during different phases and analyzed statistically using SPSS 18.0. RESULTS: Container positivity was found statistically significant at Bengaluru and Alappuzha, Kerala while in Delhi, it was found non-significant. Eggs collected from experimental containers were significantly higher in comparison to control at all the locations except Delhi. Also larvae collected from control containers were significantly higher at all the locations except Bengaluru. Pupae collected from control containers remained significantly higher at all the locations as no pupal formation was recorded from experimental containers. INTERPRETATION & CONCLUSION: The use of C21 attracticide hampered pupal formation, thus inhibiting adult population in the study areas. The study established that C21 attracticide was efficacious in the field conditions and has potential for use in surveillance and management of dengue and chikungunya mosquitoes.

Impact of deforestation on known malaria vectors in Sonitpur district of Assam, India.

BACKGROUND & OBJECTIVES: An alarming rate of deforestation has been reported from Sonitpur district of Assam, India therefore, a study was initiated during 2009 using remote sensing (RS) to assess deforested areas in the district and to study the impact on malaria vectors in order to formulate appropriate control strategy. METHODS: RS imageries of 2000 and 2009 were used to assess deforested areas in the selected district. Entomological data were collected in four surveys during 2009-2011. The data were analyzed statistically using test of single proportions (χ 2 ) and pair-wise comparison. Vector incrimination was done using enzyme-linked immunosorbent assay (ELISA) and entomological inoculation rate (EIR) was calculated to estimate transmission intensity. RESULTS: The deforested areas were identified in north-western parts of Sonitpur district falling in Dhekiajuli Primary Health Centre (PHC). The forest cover of the PHC decreased >50% during 2000-2009. Five species of anopheline vectors were collected. Anopheles minimus sensu lato (s.l.) was collected least abundantly while An. culicifacies s.l. prevailed most abundantly and significant difference was observed between proportions of the collected vector species. Pair-wise comparison between An. culicifacies s.l. and An. minimus s.l. was also found statistically significant indicating that An. culicifacies s.l. is establishing its population in deforested areas. An. culicifacies s.l. was found ELISA positive and EIR was measured as 4.8 during transmission season. CONCLUSION: An. culicifacies s.l. replaced An. minimus s.l., the vector of malaria in northeast India and was found ELISA positive, therefore could have possible role in malaria transmission in the deforested areas of the district.

Identification of risk factors for malaria control by focused interventions in Ranchi district, Jharkhand, India.

BACKGROUND & OBJECTIVES: Ranchi, the capital of Jharkhand state is endemic for malaria, particularly the Bundu Primary Health Centre (PHC) is the worst affected. Therefore, a study was initiated during 2009 using remote sensing (RS) and geographical information system (GIS) to identify risk factors responsible for high endemicity in this PHC. METHODS: Bundu and Angara in Ranchi district were identified as high and low malaria endemic PHCs based on epidemiological data of three years (2007-09). The habitation, streams, other water body, landform, PHC and village boundary thematic maps were prepared using IRS-P6/LISS III-IV imageries and macro level breeding sites were identified. Digital elevation model (DEM) of the PHCs was generated using Cartosat Stereo Pair images and from DEM, slope map was derived to calculate flat area. From slope, aspect map was derived to indicate direction of water flow. Length of perennial streams, area under rocky terrain and buffer zones of 250, 500 and 750 m were constructed around streams. High resolution remote sensing imageries were used to identify micro level breeding sites. Based on macro-micro breeding sites, six villages from each PHC were selected randomly having combination of different parameters representing all ecotypes. Entomological data were collected during 2010-11 in pre- and post-monsoon seasons following standard techniques and analyzed statistically. Differential analysis was attempted to comprehend socioeconomic and other determinants associated with malaria transmission. RESULTS: The study identified eight risk factors responsible for higher malaria endemicity in Bundu in comparison to Angara PHC based on ecological, entomological, socioeconomic and other local parameters. CONCLUSION: Focused interventions in integrated vector management (IVM) mode are required to be carried out in the district for better management and control of disease.

A spatial statistical approach to analyze malaria situation at micro level for priority control in Ranchi district, Jharkhand.

BACKGROUND & OBJECTIVES: The presence of efficient malaria vectors namely Anopeles culicifacies, An. fluviatilis and An. annularis (Diptera: Culicidae), rapid industrialization causing large influx of population and poor health infrastructure are some of the factors that make malaria an important public health problem in Ranchi, the capital of Jharkhand State, India. A geographical information system (GIS) based retrospective study using spatial statistical tools was initiated in 328 subcentres of 14 primary health centres (PHCs) of the district using malaria epidemiological data of three years (2007-2009) to identify spatial distribution pattern of Plasmodium vivax (Pv) and Plasmodium falciparum (Pf) occurrence, delineation of hot spots and to map directional distribution trend of Pf spread to help formulate evidence-based policy and to prioritize control during 2011. METHODS: Spatial statistics tools like Global Moran's I index, Getis-Ord Gi* and Standard Deviational Ellipse were used in GIS domain for analysis. RESULTS: Spatial distribution pattern of Pv occurrence was found random while Pf distribution was significantly clustered. During 2007-2009, the number of subcentres under Pf hot spot category exhibited downward trend while high Pf risk subcentres exhibited upward trend. One consistent Pf hot spot consisting of five subcentres was identified in Silli PHC. During 2009, one Pf hot spot consisting of 20 subcentres and 18 subcentres under high Pf risk category were identified in Angara, Silli, Burmu and Kanke PHCs. A shifting trend in Pf spread was noticed from north-west to western direction from 2008 onwards. INTERPRETATION & CONCLUSIONS: The study recommended priority control in 20 Pf hot spot and 18 high Pf risk reporting subcentres including five consistent Pf hot spot subcentres in Angara, Silli, Burmu and Kanke PHCs during 2011 to address grave malaria situation in the district in a cost-effective manner.

Retrospective study of chikungunya outbreak in urban areas of India.

BACKGROUND & OBJECTIVES: A retrospective study on chikungunya outbreak in India in five States viz. Delhi, Madhya Pradesh, Orissa, Maharashtra and Kerala was conducted in 2007-2008 to know the distribution and determinants of chikungunya fever outbreak in India. METHODS: On the basis of high and low incidence of chikungunya fever, two districts from each State and two wards from the selected district were taken for random selection of 1000 households from 10 districts and 5 States. Semi-structured questionnaires were administered to individuals, patients, qualified health professionals and to stakeholders for collecting information. RESULTS: The educational background and occupation of the respondents showed variations across the study States. Only in high incidence ward of Maharashtra, water storage period for 3-6 days and emptying, drying of water containers on weekly basis was noted. The study through knowledge, attitude, belief, practice (KABP) obtained individual's perception of chikungunya fever, its prevention and control. Patients' expenditure on treatment was mainly recorded less than Rs 500 across study States. Health facility survey obtained an overview of the capacity of local health facilities. Stakeholders' perception regarding chikungunya fever was also noted. INTERPRETATION & CONCLUSIONS: The study revealed differences in awareness of chikungunya, cause of the disease, vector responsible, mode of transmission, biting time and elimination of breeding of mosquitoes statistically significant among high and low incidence wards of all the States. Expenditure on treatment was independent of economically active status and loss of man-days across all the States. Education and occupation did not have any relation with emptying/drying of water containers in high incidence wards. Strengthening of surveillance, information, education and communication (IEC) activities along with case management facilities may be provided by the State health department for prevention of chikungunya outbreaks in future. Stakeholders should be more involved in outbreak management and future planning.

Resting behaviour of Anopheles stephensi type form to assess its amenability to control malaria through indoor residual spray.

BACKGROUND & OBJECTIVES: In the present study, an attempt was made to find reasons of ineffectiveness of indoor residual spray to interrupt malaria transmission by investigating the behaviour of two variants of Anopheles stepnesi, viz. type form and mysorensis in rural areas of Rajasthan, India. METHODS: Both low malarious (DDT spray from 1958 to 1976) and high malarious (DDT spray from 1958 to April 2006) villages were selected for the study in Arid zone district Jodhpur, Rajasthan during March-April 2006. Resting behaviour of the species during all its movement rhythms covering 24 h period related to: (i) swarming/ mating; (ii) pre- and post-biting rest; (iii) after feed resting between hoping movements; (iv) night and day time resting and; (v) diel activity movements in response to temperature changes, were carried out. RESULTS: The results showed that household objects like cupboards, furnitures, hanging clothes, goods stacked on loft, stored clothes, cobwebs and floor were the dominant resting sites both in sprayed and unsprayed villages. About 95 and 97% of An. stephensi preferred to rest on household objects of unsprayed and sprayed villages respectively. There was no significant difference in resting behaviour of the species in both groups of villages (p >0.05). The pre-biting resting time was recorded as 5 to 15 min whereas post-biting resting time lasted for 15 to 25 min. After biting outdoor (in courtyard--open to sky) species starts entering the rooms at around 2330 hrs. It was observed that during III quarter (0100 to 0400 hrs) maximum species entered into the room were 56% in unsprayed and 62% in sprayed villages. Statistically there was no significant difference in the entry of mosquitoes (p >0.05) in both the groups of villages. CONCLUSION: Before DDT era, An. stephensi was found resting at all heights of the walls inside the human dwellings. Present study revealed that An. stephensi is trying to avoid sprayable surfaces and tend to rest on unsprayable surfaces during all its movement rhythms starting from swarming, pre-/post-biting and during hopping movements in the courtyard and thereafter household objects inside the room as final day time resting. It was concluded that changed behaviour of resting of An. stephensi on unsprayable objects in sprayed rooms largely accounted for failure of malaria control. Control of An. stephensi, thus requires an integrated vector control strategy based upon interesectoral, environmental, larviciding with chemical/biolarvicide and use of larvivorous fish wherever feasible. Such a control strategy offers cost-effective and sustainable option than indoor residual spray.

Utilization of the castor seed cake (biowaste) for mosquito vector control.

The present work is related to the utilization of castor (Ricinus communis) seed cake, biowaste produced during the oil extraction of castor seeds, as efficient mosquitocidal composition against Aedes aegypti and Anopheles culicifacies. The efficacy of coil formulations was evaluated in the Peet Grady chamber and resulted in 90% and 100% knocked down and mortality against A. aegypti and A. Culicifacies, respectively. Further heavy metals' (Cr, Pb, Co, As, Cd, Cu, Mn, and Zn) analysis of the coil was performed using Inductively Coupled Plasma mass spectrometry and was compared with commercially available mosquito repellent coil. Heavy metal analysis revealed that commercial repellent coil had a higher content of heavy metals than the castor seed cake coil. Finding of the present research study indicates that castor seed cake coil has the potential to be used in mosquito vector control. Castor seed cake coil formulation will also open up avenues in future for sustainable utilization of the biowaste.

Social and environmental risk factors for dengue in Delhi city: A retrospective study.

Global urbanization is leading to an inexorable spread of several major diseases that need to be stemmed. Dengue is one of these major diseases spreading in cities today, with its principal mosquito vector superbly adapted to the urban environment. Current mosquito control strategies are proving inadequate, especially in the face of such urbanisation and novel, evidence-based targeted approaches are needed. Through combined epidemiological and entomological approaches, we aimed to identify a novel sanitation strategy to alleviate the burden of dengue through how the dengue virus spreads through the community. We combined surveillance case mapping, prospective serological studies, year-round mosquito surveys, socio-economic and Knowledge Attitudes and Practices surveys across Delhi. We identified lack of access to tap water (≤98%) as an important risk factor for dengue virus IgG sero-positivity (adjusted Odds Ratio 4.69, 95% C.I. 2.06-10.67) and not poverty per se. Wealthier districts had a higher dengue burden despite lower mosquito densities than the Intermediary income communities (adjusted Odds Ratio 2.92, 95% C.I. 1.26-6.72). This probably reflects dengue being introduced by people travelling from poorer areas to work in wealthier houses. These poorer, high density areas, where temperatures are also warmer, also had dengue cases during the winter. Control strategies based on improved access to a reliable supply of tap water plus focal intervention in intra-urban heat islands prior to the dengue season could not only lead to a reduction in mosquito abundance but also eliminate the reservoir of dengue virus clearly circulating at low levels in winter in socio-economically disadvantaged areas.

Identification of malaria hot spots for focused intervention in tribal state of India: a GIS based approach.

BACKGROUND: In India, presently malaria shows a declining trend whereas Plasmodium falciparum (Pf) cases show an up trend. In central India, specifically, Madhya Pradesh (M.P.) a forested and tribal area, control of malaria is logistically difficult and outbreaks are frequently recorded, reasons for this being inadequate surveillance, poor reporting, a time lag in reporting to decision makers and a lack of geo referenced information to pin point the trouble spots for a timely preventive action. RESULTS: An information management system based on Geographic Information System (GIS) using district and block wise malaria data, has been constructed for Madhya Pradesh for quick retrieval of info and dynamic generation of maps to highlight hot spots of malaria for formulating prompt and focused malaria control strategy. Out of total 48 districts consisting of 313 blocks, based on certain criteria GIS identified 58 blocks falling in 25 districts as Hot Spots. Malaria flares up from these pockets whenever favourable conditions for transmission occurs. It was suggested to National Vector Borne Disease Control Programme (NVBDCP) that focused malaria control in these hot pockets may be taken up on priority during the year 2007, it was implemented by State Health Authorities, M.P. under the directive of NVBDCP. Implementation of control measures were evaluated by NVBDCP. CONCLUSION: GIS mapping would make it easy to update information instantly and to identify the trouble spots at the village level within the district which is the lowest unit equipped with computer facilities and the information can reach instantly to state and the policy makers to formulate focused and cost effective malaria control strategy. This is the first time when GIS has been used in national control programme for tribal malaria.