P. Jambulingam

DNA Barcodes Can Distinguish Species of Indian Mosquitoes (Diptera: Culicidae)

Abstract Species identification of mosquitoes (Diptera: Culicidae) based on morphological characteristics remains often difficult in field-collected mosquito specimens in vector-borne disease surveillance programs. The use of DNA barcodes has been proposed recently as a tool for identification of the species in many diverse groups of animals. However, the efficacy of this tool for mosquitoes remains unexplored. Hence, a study was undertaken to construct DNA barcodes for several species of mosquitoes prevalent in India, which included major vector species. In total, 111 specimens of mosquitoes belonging to 15 genera, morphologically identified to be 63 species, were used. This number also included multiple specimens for 22 species. DNA barcode approach based on DNA sequences of mitochondrial cytochrome oxidase gene sequences could identify 62 species among these, in confirmation with the conventional taxonomy. However, two closely related species, Ochlerotatus portonovoensis (Tiwari & Hiriyan) and Ochlerotatus wardi (Reinert) could not be identified as separate species based on DNA barcode approach, their lineages indicating negligible genetic divergence (Kimura two-parameter genetic distance = 0.0043).

DNA barcoding for identification of sand flies (Diptera: Psychodidae) in India

About 50 species of sand flies have been reported to be prevalent in India. We explored the utility of the DNA barcode approach towards species identification of these medically important insects. A total of 62 specimens belonging to seven morphologically identified species of two genera, Phlebotomus and Sergentomyia, collected from Puducherry Union Territory, Maharashtra and Rajasthan states of India were subjected to the analysis. Neighbor‐joining (NJ) analysis of DNA barcode sequences identified the individuals of seven morphological species into eight distinct species, as presented in the designed NJ tree. This methodology delineated morphologically identified species, S. bailyi, into two genetically isolated groups. Also, this study characterizes DNA barcodes of P. argentipes and P. papatasi, the vector species of leishmaniasis in India, for the first time.

Knowledge, attitude and practice on malaria: A study in a tribal belt of Orissa state, India with reference to use of long lasting treated mosquito nets

Local knowledge and practice related to malaria is important for the implementation of culturally appropriate, sustainable and effective interventions. In this context, to know peoples knowledge, attitude and practice on malaria and its prevention, a study was carried out in two districts viz., Malkangiri and Koraput of Orissa state in India, the former with ongoing insecticide treated mosquito nets (ITNs) programme and the latter without such programme (non-ITNs). Both qualitative and quantitative methods were used for data collection. The local concepts used for malaria describe only the biomedical symptoms of the disease although a few by meaning in local language reflect peoples misconceptions about the cause of malaria. About 63% of the respondents mentioned mosquito bite as the cause for this disease and 65% considered malaria as a serious problem. Qualitative data showed that people from remote villages seek treatment from traditional healers, Disharis. About 64% of the respondents stated that avoiding mosquito bites could prevent malaria. Majority (99%) of the people reported using personal protection measures to avoid mosquito bites. Although, majority of the people were aware of the cause and prevention of malaria (about 70% stated sleeping under mosquito net prevents malaria), a sizable proportion still had misconceptions and hence appropriate communication strategies should be developed and imparted alongside ITNs/LLINs distribution for a behaviour change to adopt such preventive measures. Since, the tribes are habituated to seek treatment from traditional healers; they could be involved in motivating people to use ITNs/LLINs to protect from mosquito bites and malaria.

Acceptability, willing to purchase and use long lasting insecticide treated mosquito nets in Orissa State, India

Long lasting insecticide treated nets (LLINs) that require no re-treatment have been advocated as an effective tool against malaria transmission. However, success of this community based intervention measure largely depends on its acceptability and proper usage by the target population, besides assuring access to bed nets. To determine the acceptability of LLIN, its usage and peoples willingness to buy the net, a study was conducted in two tribal districts viz., Malkangiri (with ongoing ITN programme) and Koraput (no ITN programme) of Orissa State, India. Both qualitative and quantitative data collection methods were used to collect information regarding the objective of the study. A total of 2457 LLINs (Olyset Nets) were distributed in the selected villages of these districts at free of cost. In the study villages of Malkangiri, 58% of the households had either ITNs (73%) or other types of mosquito nets aside from the LLINs and in the villages of Koraput, only 8% had other nets, as majority (96%) informed that buying nets from market was not affordable to them. Physical verification of the nets during the house visits revealed that 75.4% and 83% (in ITNs and non-ITNs villages, respectively) of the LLINs and 76% of the other nets (including ITNs) were used by the respondents, the night before the survey as nets were in a hanging position at the time of the visit. Majority of the respondents (76-98%) felt that reduction of mosquito bites as the main perceived benefit of using the LLINs. About 55% and 67% of the respondents from non-ITNs and ITNs areas, respectively, expressed their willingness to buy the LLINs. Among them, 76.8% and 94.7% offered to pay INR<100 for a net and also ready to buy it by cash payment. Social marketing of LLINs at a subsidized price or free supply to the deserving sections of people (socially/economically poor and/or under-privileged) and ensuring the availability of nets during harvesting season could encourage people to buy and use LLINs.

Population movement and malaria persistence in Rameswaram Island: Foreword

During 1982-84, the Vector Control Research Center (VCRC) of the Indian Council for Medical Research (ICMR) at Pondicherry studied the role of population movement in the persistence of malaria transmission in Rameswaram Island, Tamil Nadu, between mainland India and Sri Lanka. While the island supports a population of 56,000, mostly fishermen, there is also a periodic, back and forth migration of fishermen between mainland villages and Rameswaram. This population movement greatly contributes to the high prevalence of malaria in both areas, since fishermen can be either donor or recipient of malaria in either place. The VCRC monitered and recorded the movement of fishermen in various seasonal camps by questioning them and by the VCRC staff accompanying them when possible. In 9 fishing camps 412 of 1098 families had migrated from mainland villages; 686 families had migrated from villages within Rameswaram Island. A mass blood survey found 138 of 4073 individuals examined positive for malaria; 107 of 680 fever cases examined were positive for malaria. Mosquito collections, the lack of permanent treatment facilities for the transient population, and ecological factors indicate a high receptivity for malaria on Rameswaram Island. With the island attracting between 1000-4000 tourists daily and over 200,000 travelers annually between India and Sri Lanka, evidence exists for considerable danger from the importation of chloroquinine resistant malaria strains into Rameswaram. Adequate attention to human ecology will be needed for malaria control in this area.

Reliability of light trap sampling for Anopheles fluviatilis, a vector of malaria.

The utility of light traps for sampling Anopheles fluviatilis, the major malaria vector in the hill tracts of Koraput district, Orissa, was assessed. A modified version of the CDC miniature light trap was used in the study. The data generated from light trap collections were analysed and compared with daytime resting, man-biting and night resting collections carried out in parallel. The number per trap recorded in cattle sheds was significantly higher than that recorded in human dwellings. A similar pattern was observed in hand catches of indoor resting population though the difference was not significant. The density recorded from light traps over time was found to have a significant positive linear association with corresponding indoor (r = 0.625; p = 0.0019) as well as outdoor (r = 0.603; p = 0.0029) diurnal resting densities. The proportion with different gonotrophic stages varied significantly between different types of collections. The age structure of A. fluviatilis did not differ significantly with the types of collection. As the light trap catches reflect seasonal fluctuations in the diurnal resting collections, they can justifiably be used in monitoring the relative density of A. fluviatilis in the place of cumbersome hand catch methods. Other uses of light traps are also discussed.

Glutathione S Transferase Activity in Indian Vectors of Malaria: A Defense Mechanism Against DDT

ABSTRACT Glutathione S transferases (GSTs) are multifunctional enzymes involved in detoxification of xenobiotic compounds in majority of the insect groups. Significance of insect GSTs is their elevated level of activity in association with insecticide resistance. This investigation was to explore the metabolic status of GSTs in two Indian DDT-resistant malaria vectors, Anopheles culicifacies and Anopheles annularis, and one DDT-susceptible vector, Anopheles fluviatilis. Malkangiri and Koraput districts of Orissa State, endemic for falciparum malaria and having a long insecticide spraying history, were the study areas. F1 progeny was raised from wild-caught females of the three vectors and used for biochemical assays to detect the GST-mediated DDT resistance mechanism. Results of the enzyme assay showed a significant 3-fold increase in GST activity in DDT-resistant An. annularis compared with its susceptible population. In DDT-resistant An. culicifacies, the median GST activity (71.8 µmol/min/mg) was almost the same as estimated in the DDT-resistant An. annularis (74.6 µmol/min/mg), suggesting that the GST activity estimated in An. culicifacies could be an elevated level for detoxification of DDT. Furthermore, the GST activity in DDT-resistant An. culicifacies and An. annularis was significantly higher than that in the DDT-susceptible An. fluviatilis, which had a GST activity of 20.0 µmol/min/mg. Also, the GST-mediated DDT detoxification was confirmed by comparing GST activity in wild-caught females with that in their F1 progeny.

Persistent foci of falciparum malaria among tribes over two decades in Koraput district of Odisha State, India

BackgroundKoraput, a predominantly tribe-inhabited and one of the highly endemic districts of Odisha State that contributes a substantial number of malaria cases to the India’s total. Control of malaria in such districts would contribute to change the national scenario on malaria situation. Hence, a study was carried out to measure the magnitude of malaria prevalence in the district to strengthen the malaria control activities.MethodsPrevalence of malaria was assessed through a sample blood survey (SBS) in seven randomly selected community health centres (CHCs). Individuals of all age groups in the villages selected (one in each subcentre) were screened for malaria infection. Both thick and thin smears were prepared from blood samples collected by finger prick, stained and examined for malaria parasites searching 100 fields in each smear. The results of a blood survey (n = 10,733) carried out, as a part of another study, during 1986–87 covering a population of 17,722 spread in 37 villages of Koraput district were compared with the current survey results. Software SPSS version 16.0 was used for data analysis.ResultDuring the current study, blood survey was done in 135 villages screening 12,045 individuals (16.1% of the total population) and among them, 1,983 (16.5%) were found positive for malaria parasites. Plasmodium falciparum was the major malaria parasite species accounted for 89.1% (1,767) of the total positives; Plasmodium vivax and Plasmodium malariae accounted for 9.3% (184) and 0.2% (5), respectively. Gametocytes were found in 7.7% (n = 152) of the positive cases. The majority of parasite carriers (78.9%) were afebrile. The 1986–87 blood survey showed that of 10,733 people screened, 833 (7.8%) were positive for malaria parasites, 714 (85.7%) with P. falciparum, 86 (10.3%) with P. vivax, 12 (1.4%) with P. malariae and 21 (2.5%) with mixed infections.ConclusionThe results of the current study indicated a rising trend in transmission of malaria in Koraput district compared to the situation during 1986–87 and indicated the necessity for a focused and reinforced approach for the control of the disease by improving people’s access to diagnosis and treatment and ensuring implementation of the intervention measures with adequate coverage and compliance.

Bionomics of Anopheles minimus and An. fluviatilis (Diptera: Culicidae) in east-central India, endemic for falciparum malaria: human landing rates, host feeding, and parity.

ABSTRACT The host feeding of Anopheles minimus Theobald and An. fluviatilis James was studied in the villages of east-central India by conducting human landing collections between 1800 and 0600 hours at monthly intervals from May 2006 to July 2007. Four species of anopheline mosquitoes, An. minimus, An. fluviatilis, An. maculatus Theobald, and An. subpictus Grassi, were collected, the former two known vector species of malaria being the most abundant (97.1%). The An. minimus complex has been identified as sibling species A and An. fluviatilis complex as species S (90.9%) and T (9.1%). Both the species were prevalent throughout the year and obtained from landing collections indoors and outdoors. The average human landing density (HLD) of An. minimus and An. fluviatilis was 1.76 and 1.78 indoors and 1.71 and 1.56 per human per night outdoors, respectively. The HLD was relatively higher during the rainy season, although not significant in the case of An. fluviatilis. The human landing activity of An. minimus and An. fluviatilis occurred between 2000 and 0400 hours and peaked during 2300–0200 hours both indoors and outdoors.

Efficacy of Two Formulations of the Bioinsecticide Spinosad Against Culex quinquefasciatus in India

Abstract Spinosad 12% suspension concentrate (SC) and 0.5% granular (G) formulations were tested against Culex quinquefasciatus immatures at 3 dosages—50, 100, and 150 mg active ingredient (AI)/m2—in cesspits, street drains, and disused wells in comparison with temephos 1% G at 1 part per million. The 2 formulations reduced the density of pupae of Cx. quinquefasciatus by 80–100% for 7–14 days in cesspits, 7–18 days in drains, and 33–69 days in disused wells at the 3 dosages tested. The 12% SC and 0.5% G formulations were equally effective in suppressing the larval and pupal populations of Cx. quinquefasciatus in all the habitats treated. At 100 mg AI/m2 in drains and cesspits, the efficacy of spinosad 0.5% G was greater than that of temephos (1% G) and that of spinosad 12% SC was comparable to that of temephos (1% G) applied to the 2 habitats. In disused wells, both the formulations lasted longer than temephos. Based on the small-scale trial, the rate of 150 mg AI/m2 of spinosad was selected for field application to cesspits and drains and 50 mg AI/m2 for application to disused wells. The efficacy observed in medium-scale trials was in agreement with that of small-scale trials. The trial showed that the 2 formulations of spinosad can be used for larval control of Cx. quinquefasciatus, at 50 mg AI/m2, applied at weekly intervals to cesspits and street drains and at monthly intervals to disused wells. At the higher dose of 150 mg AI/m2, the 2 formulations were effective in suppressing the pupal population for 2 wk in cesspits and street drains and for 2 months in disused wells.