Journal of Vector Borne Diseases
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Item Bioecology of An. philippinensis in Andaman group of islands.(2003-03-04) Das, M K; Nagpal, B N; Srivastava, Aruna; Ansari, M AStudies on bioecology of An. philippinensis a vector of malaria was carried out in eight islands of the Andaman group. It was found that An. philippinensis preferred to rest and bite outdoors. Maximum biting was observed during 1800 to 2100 hrs on both cattle and human bait. The maximum breeding of An. philippinensis was recorded in slow moving stream followed by ponds with vegetation. The breeding sites infested with Chara and Spirogyra algae were most favourable whereas, with Lemna and Oscillatoria were unfavourable for the proliferation of this species. The breeding association of An. philippinensis was found with other seven anopheline species in different breeding habitats.Item Malaria genome project and its impact on the disease.(2003-03-04) Verma, Poonam; Sharma, Y DMalaria remains uncontrolled to-date due to lack of effective parasite and vector control strategies. With the completion of the host, parasite and vector genome projects more suitable and effective disease control measures can be achieved. Here we have reviewed the Plasmodium falciparum genome project and its impact on malaria research in future. The parasite genome project has revealed certain metabolic pathways which can be targeted to develop antimalarial drugs. It has also identified large number of potential antigens for the future potential vaccines. Now the researchers in the malaria field can plan to take up the studies, which can yield more fruitful results within the limited financial resources using bioinformatics, proteomics, structural, functional and comparative genomics, etc.Item Insecticide treated nets: impact on vector populations and relevance of initial intensity of transmission and pyrethroid resistance.(2003-03-04) Curtis, C F; Jana-Kara, B; Maxwell, C AInsecticide treated bednets locate a deposit of a quick-acting insecticide of low human toxicity between a sleeper and host-seeking mosquitoes. Thus a chemical barrier is added to the often incomplete physical barrier provided by the net. Treated nets may be considered as mosquito traps baited by the odour of the sleeper. Trials in Assam, Tanzania and elsewhere have shown that when a whole community is provided with treated nets, so many mosquitoes of anthropophilic species are killed by contact with the nets that the density and/or sporozoite rate of the vector population is reduced. In order to gain this "mass" or community effect, in addition to widespread personal protection, and thus to achieve the full potential of the treated net method, a high per cent coverage of the community is needed. This suggests that organised free provision of treated nets, comparable to a house spraying programme, is likely to be more cost-effective than trying to market nets and insecticide to very poor rural people. In areas with high malaria transmission, where acquisition of immunity to malaria is very important, it has been argued that vector control (without vector eradication) could, in the long run, make the situation worse by preventing the normal build-up of immunity. However, our data from Tanzania do not support this idea--3-4 years after provision of nets (which are re-treated annually) young children are still showing clear health benefits; older children are not "paying" for this by showing worse impact of malaria. There is less malaria morbidity in a highland area where malaria transmission is about 15x less intense than in a nearby lowland area. The per cent impact of treated nets malaria morbidity in both area was very similar. At present only pyrethroids are used for net treatment which suggested that emergence of pyrethroid resistance would have a disastrous effect. However, in West Africa, where there is now a high frequency of the kdr resistance gene in Anopheles gambiae, it is reported that treated nets continue to have a powerful impact on vector populations. In Tanzania, pyrethroid resistance has not been detected in malaria vectors, but it has emerged in bedbugs after seven years use of treated nets.Item Evaluation of botanicals as repellents against mosquitoes.(2003-03-04) Das, N G; Baruah, I; Talukdar, P K; Das, S CRepellent properties of three plant extracts--essential oil (steam distillate) of Zanthoxylum limonella (fruits), Citrus aurantifolia (leaf) and petroleum ether extract of Z. limonella (fruits) were evaluated as repellent against Aedes (S.) albopictus mosquitoes in mustard (Dhara) and coconut (Parachute) oil base under laboratory conditions. Three concentrations--10, 20 and 30% of the repellents were evaluated. Repellents in mustard oil afforded longer protection time against the bites of Aedes (S.) albopictus mosquitoes than those in coconut oil. At 30% concentration, 296-304 min protection time was achieved by the test repellents in mustard oil base while repellents in coconut oil exhibited 223.5-245 min protection time at the same concentration. Oil of Z. limonella gave the highest protection time against the bites of Aedes (S.) albopictus mosquitoes at all the concentrations than other herbal repellents tested both in mustard and coconut oil.Item Genetics of resistance to permethrin in Anopheles stephensi.(2003-03-04) Hodjati, M H; Curtis, C FItem Biolarvicides in vector control: challenges and prospects.(2003-03-04) Mittal, P KBiolarvicides, based on mosquitocidal toxins of certain strains of Bacillus sphaericus and Bacillus thuringiensis var israelensis H-14 (Bti) are highly effective against mosquito larvae at very low doses and safe to other non-target organisms. During past two decades various biolarvicide formulations produced in India and abroad have been tested at Malaria Research Centre and some formulations have undergone large-scale operational trials. Biolarvicide formulations of B. sphaericus are useful in the control of Culex and certain Anopheles spp, such as An. stephensi and An. subpictus, but not much effective against An. culicifacies and almost ineffective against Aedes aegypti. Repeated application of B. sphaericus in the same habitat, however, results in the development of resistance in larvae of target mosquitoes. In view of its low specificity for An. culicifacies and the potential for resistance in An. stephensi, B. sphaericus has limited prospects for control of malaria vectors. However, with some resistance management, B. sphaericus can still be used against Culex mosquitoes. On the other hand Bti formulations, which have broader spectrum of activity against Aedes, Culex and Anopheles spp, have not shown significant development of resistance in mosquitoes but their activity in field, particularly against surface feeding anopheline larvae is affected by various bioenvironmental factors, thus requiring weekly application in most habitats. To overcome this problem development of slow release formulations and genetically engineered biolarvicides by transplanting mosquitocidal toxin genes of Bti and B. sphaericus in some other environmentally compatible organisms have been investigated by different scientists.Item Bio-efficacy and operational feasibility of alphacypermethrin (Fendona) impregnated mosquito nets to control rural malaria in northern India.(2003-03-04) Ansari, M A; Razdan, R KBio-efficacy and operational feasibility of alphacypermethrin treated nets was evaluated in certain villages of District Ghaziabad (U.P.). Results revealed that poly-filament nylon nets treated with alphacypermethrin suspension concentrate (g/l) formulation @ 25 mg/m2 has shown repellent action (26.5 +/- 8.1), excito repellent action (93.7 +/- 8.1) and killing action (100%) against An. culicifacies landed on treated nets. Significant reduction in indoor resting density of An. culicifacies in human dwellings was also observed in treated nets village (p < 0.05). Instant killing action of treated nets did provide complete protection to inhabitants sleeping inside the net from An. culicifacies bites. The persistent use of nets by the inhabitants has also resulted significant reduction in malaria cases (p < 0.05). It was interesting to note that not even a single case of falciparum malaria was observed after distribution of treated nets in spite of the fact that at no point of time cent per cent compliance of net usage was observed during the study period. Bio-assay tests revealed that treated nets can produce up to 70% mortality in An. culicifacies for about 22 weeks and as such only one treatment with insecticide is required in a year in seasonal transmission area to protect from malaria. The study also revealed that treated nets can be stored at room temperature for about 10 months without loosing their efficacy suggesting thereby that malaria outbreaks can be tackled by the nets if adequate treated nets are stored in core problem districts. It was also revealed that An. culicifacies is a late night biter and as such treated nets can be used successfully against this species.Item Malaria morbidity and mortality in Uganda.(2003-03-04) Kiwanuka, Gertrude NItem Irritant effect, prevention of blood feeding and toxicity of nets impregnated with different pyrethroids on An. stephensi.(2003-03-04) Hodjati, M H; Mousavi, N; Curtis, C FA resistant strain of An. stephensi was confirmed to have high resistance to knock down and kill by four different pyrethroids in bioassays in comparison with a susceptible strain. Permethrin, lambda-cyhalothrin and deltamethrin were more irritant to the susceptible strain than the resistant as judged by time for first take-off, but nets treated with alphacypermethrin appeared to be more irritant to the resistant An. stephensi than the susceptible. With all the pyrethroids tested, the resistant strain spent a longer time in contact with a treated net, which was in contact with a human arm, than did the susceptible strain. With permethrin the resistant strain fed significantly more successfully through the treated netting than did the susceptible strain. With deltamethrin there was a non-significant tendency in the same direction in comparing the two strains. However, with alphacypermethrin there was a non-significant tendency in the reverse direction. After 15 min in the cage which tested for the ability to feed through a pyrethroid treated net, observed mortality was higher with the susceptible than the resistant strain. Thus there was no sign that the longer resting of the resistant strain on treated netting would compensate for the fact that a higher dose was needed to kill this strain. Such compensation has been suggested with West African An. gambiae where treated nets continue to work well against a highly resistant wild population. However, this does not seem to apply to our resistant An. stephensi.Item Testing of newly developed glycophospholipid antigen for the detection of P. falciparum malaria by laser light immunoassay in endemic and non-endemic areas.(2003-09-04) Roy, A; Biswas, S; Mya, M M; Saxena, R K; Roy, K BA glycophospholipid (GPL) antigen isolated from Plasmodium falciparum culture supernatant has been tested for its antigenicity. Detection of malaria positive known blood samples and unknown field samples from endemic and non-endemic areas were compared. In this study laser light scattering immunoassay (LIA) was used for the detection of P. falciparum malaria. Test results of control (malaria negative samples from Surat) were compared with known positive samples and unknown malaria positive field samples. A positive correlation has been observed (97%) in falciparum positive samples from laboratory and unknown samples from endemic area (Haldwani) by LIA method using GPL antigen. From the results of the study it was found that GPL antigen has a better antigenic property and can detect almost all the cases of Pf malaria by LIA method.Item Drug resistant falciparum malaria and the use of artesunate-based combinations: focus on clinical trials sponsored by TDR.(2003-09-04) Taylor, Walter R; Rigal, Jean; Olliaro, Piero LAntimalarial drug resistance has now become a serious global challenge and is the principal reason for the decline in antimalarial drug efficacy. Malaria endemic countries need inexpensive and efficacious drugs. Preserving the life spans of antimalarial drugs is a key part of the strategy for rolling back malaria. Artemisinin-based combinations offer a new and potentially highly effective way to counter drug resistance. Clinical trials conducted in African children have attested to the good tolerability of oral artesunate when combined with standard antimalarial drugs. The cure rates of the different combinations were generally dependent on the degree of resistance to the companion drug. They were high for amodiaquine-artesunate, variable for sulfadoxine/pyrimethamine-artesunate, and poor for chloroquine-artesunate.Item An inventory of Culicidae diversity in Haryana state.(2003-09-04) Kaur, Jagdish; Kirti, Jagbir SItem Markers for population genetic analysis of human plasmodia species, P. falciparum and P. vivax.(2003-09-04) Joshi, HemaPresent report deals with the genetic diversity existing among the field isolates of Plasmodium falciparum and P. vivax in India. Isoenzymes and molecular markers were used to analyse field isolates of P. falciparum and P. vivax. High level of length polymorphism was observed in repeat nucleotide sequences of MSP-1, MSP-2 and GLURP in P. falciparum isolates and CSP, GAM-1 and MSP-3 alpha in P. vivax isolates. In study populations a high proportion of isolates (up to 60%) were comprised of more than one genetically distinct parasite type--multiclonal. Presence of identical allelic forms of enzyme and DNA variations in different geographical areas and in different years suggest that isolates belong to a single random mating population of P. vivax and P. falciparum. Observed random combination of alleles in the field isolates suggest the unlinked nature of loci studied. Study supports the feasibility of using molecular markers for the identification of recrudescence in P. falciparum from fresh infection.Item Evaluation of repellent action of Cymbopogan martinii martinii Stapf var sofia oil against Anopheles sundaicus in tribal villages of Car Nicobar Island, Andaman & Nicobar Islands, India.(2003-09-04) Das, M K; Ansari, M AA field study was carried out to evaluate the mosquito repellent action of Cymbopogan martinii martinii Stapf var sofia oil in tribal village of Car Nicobar Island. Results revealed that application of 1 ml of the oil provided 98.7% protection in indoor and 96.52% in outdoor conditions during 12 h period of observation from the bites of An. sundaicus. Cymbopogan martinii martinii Stapf var sofia oil is an indigenous product, its application is safe and can be widely used for protection from malaria.Item Hospital based study of malaria in Ratnagiri district, Maharashtra.(2003-09-04) Mishra, GauraviItem How specific is the immune response to malaria in adults living in endemic areas?(2003-09-04) Mannan, B A; Patel, K; Malhotra, I; Ravindran, B; Sharma, ShobhonaIt is documented that people living in malaria endemic areas acquire immunity against malaria after repeated infections. Studies involving passive transfer of IgG from immune adults to the nonimmune subjects have shown that circulating antibodies play an important role, and that immune adults possess protective antibodies, which susceptible malaria patients do not. Through a differential immunoscreen, we have identified several novel cDNA clones, which react exclusively and yet extensively with immune sera samples. Specific antisera raised against the immunoclones inhibit the growth of parasites in culture. The clones studied so far turn out to be novel conserved Plasmodium genes. In order to study the response of sera of adults from malaria endemic areas of India and Africa to these immunogens, we carried out ELISA assays using these immunopeptides, other P. falciparum specific antigens, peptides, antigens from other infections such as mycobacterial infections and other proteins such as BSA. Children from the same areas and normal healthy urban people showed very little activity to each of these categories. A large percentage of adults from endemic areas responded positively to all the malarial immunogens tested. However, the same persons also showed high response to other antigens and proteins as well. The implications of these results are reported in this paper.Item Interrupting malaria transmission by genetic manipulation of anopheline mosquitoes.(2003-09-04) Jacobs-Lorena, MarceloMalaria ranks among the deadliest infectious diseases that kills more than one million persons every year. The mosquito is an obligatory vector for malaria transmission. In the mosquito, Plasmodium undergoes a complex series of developmental events that includes transformation into several distinct morphological forms and the crossing of two different epithelia--midgut and salivary gland. Circumstantial evidence suggests that crossing of the epithelia requires specific interactions between Plasmodium and epithelial surface molecules. By use of a phage display library we have identified a small peptide-SM1--that binds to the surfaces of the mosquito midgut and salivary glands. Transgenic Anopheles stephensi mosquitoes expressing a SM1 tetramer from a blood-inducible and gut-specific promoter are substantially impaired in their ability to sustain parasite development and transmission. A second effector gene, phospholipase A2, also impairs parasite transmission in transgenic mosquitoes. These findings have important implications for the development of new strategies for malaria control.Item Assessment of therapeutic efficacy of chloroquine and sulphadoxine-pyrimethamine in uncomplicated falciparum malaria.(2003-09-04) Biswas, Sukla; Valecha, Neena; Tyagi, Prajesh K; Phookan, Shobhan; Dev, Vas; Sharma, Surya K; Subbarao, Sarala KA standardised protocol has been developed by World Health Organization (CDS/RBM/2002) to assess the efficacy of common antimalarials in the treatment of clinically manifested infection with uncomplicated P. falciparum malaria for areas with low to moderate transmission. The therapeutic efficacy protocol is based on clinical and parasitological responses of the patients and it has the purpose of determining the practical efficacy of the drug regimen in study areas with the ultimate objective of ascertaining its continued usefulness or the necessity for replacing it in the routine treatment. Present study has been conducted at seven sites--Kathiatali and Simonabasti of District Nowgaon, Assam; Sonapur and Boko of District Kamrup, Assam; Keonjhar Town, Padampur and Basudebpur of District Keonjhar, Orissa. In order to reduce the patient recruitment time, health centre close to well-defined community was identified to conduct the activities at peak malaria season by selecting local pockets and organising mobile clinics. Microscopically confirmed cases of P. falciparum were enrolled according to the criteria for inclusion and exclusion. Treatment with recommended drug was given under supervision and a follow-up schedule at various intervals for 28 days was maintained. In chloroquine (CQ) study areas, wherever patients showed treatment failure, they were treated with second line drug--sulphadoxine-pyrimethamine (SP) combination and then followed-up as per study protocol. It was observed that 30% cases showed treatment failure to CQ in District Nowgaon, where revised drug policy has already been introduced. In Kamrup district, treatment failure with CQ was found to be less than 25%, which denotes the said regimen is still effective. Almost all the patients from Padampur and Basudebpur of District Keonjhar responded to CQ, treatment failure was noticed only in two patients (3%). The antifolate combination found to be fully effective as second line and also as first line wherever revised drug policy has been introduced.Item A report on the susceptibility status of Anopheles minimus (Theobald) against DDT and deltamethrin in three districts of Assam.(2004-03-31) Baruah, Kalpana; Lal, ShivItem Evaluation of pirimiphos-methyl (50% EC) against the immatures of Anopheles stephensi/An. culicifacies (malaria vectors) and Culex quinquefasciatus (vector of bancroftian filariasis).(2004-03-31) Ansari, M A; Mittal, P K; Razdan, R K; Dhiman, R C; Kumar, ABACKGROUND & OBJECTIVES: In India, temephos and fenthion are used as larvicides in fresh and polluted waters. Since use of same insecticide may precipitate resistant, as an alternative bioefficacy of pirimiphos-methyl--an organophosphorus insecticide was evaluated against immatures of Anopheles and Culex species in different breeding habitats in District Ghaziabad (U.P.) and Goa. METHODS: Laboratory bioassays were carried out using standard WHO procedure. LC50 and LC90 were calculated using Probit analysis. Abbott's formula was used to calculate per cent corrected mortality in laboratory exposures while, Mulla's formula was applied for calculating per cent reduction in mosquito immatures under field conditions. RESULTS: Pirimiphos-methyl was found to be most effective against larvae of An. stephensi followed by An. culicifacies and Cx. quinquefasciatus. The LC50 and LC90 values against three species were 0.023, 0.032 and 0.04 ppm; and 0.045, 0.057 and 0.114 ppm respectively. In field, pirimiphos-methyl @ 200 g a.i./ha against Anopheles species and @ 300 g a.i./ha against Culex species can produce > 80% reduction in density of immatures up to one week in different habitats. Pirimiphos-methyl < 0.25 ppm is not toxic to fish. INTERPRETATION & CONCLUSION: Pirimiphos-methyl is more effective against anophelines in clean water than culicines in polluted water. This larvicide should not be used at a concentration above 0.25 ppm in habitats harbouring the larvivorous fish.