Isolation and characterization of emerging Mpox virus from India

Mpox (previously known as Monkeypox) has recently re-emerged, primarily through human-to-human transmission in non-endemic countries including India. Virus isolation is still considered as the gold standard for diagnosis of viral infections. Here, the qPCR positive skin lesion sample from a patient was inoculated in Vero E6 cell monolayer. Characteristic cytopathic effect exhibiting typical cell rounding and detachment was observed at passage-02. The virus isolation was confirmed by qPCR. The replication kinetics of the isolate was determined that revealed maximum viral titre of log 6.3 PFU/mL at 72 h postinfection. Further, whole genome analysis through next generation sequencing revealed that the Mpox virus (MPXV) isolate is characterized by several unique SNPs and INDELs. Phylogenetically, it belonged to A.2 lineage of clade IIb, forming a close group with all other Indian MPXV along with few from USA, UK, Portugal, Thailand and Nigeria. This study reports the first successful isolation and phenotypic and genotypic characterization of MPXV from India.

Deltamethrin Contact Exposure Mediated Toxicity and Histopathological Aberrations in Tissue Systems of Public Health Importance Cockroach Species Periplaneta americana and Blattella germanica

Cockroach species Periplaneta americana and Blattella germanica potentially survive in locations close to human activity. Besides spoiling food material, cockroaches also transfer pathogens of different diseases among human beings. Since the insecticides have been used extensively to control cockroaches, information on their insecticide susceptibility and toxicity at the cellular level may be crucial. In the study, deltamethrin toxicity as well as the deltamethrin-mediated cytomorphological changes in the brain, ovary and midgut of the two important cockroach species have been assessed. Different concentrations [0.00025% (0.0025 mg/ml), 0.0025% (0.025 mg/ml), 0.025% (0.25 mg/ml), 0.25% (2.5 mg/ml), 0.5% (5 mg/ml), 1% (10 mg/ml)] of deltamethrin in acetone were used to expose test species in WHO bottle assay. Knockdown was recorded after 5 min interval while delayed mortality was observed after 24 h. Brain, ovary and gut were dissected post 1 h exposure and 24 h holding (for 0.25, 0.5 and 1% concentration), and tissues were processed for microscopic analysis. Deltamethrin exposed cockroaches and dissected tissues were used to estimate deltamethrin using HPLC. At 0.00025% (lowest concentration), the percentage knock-down observed was 66.7% for P. americana and 80% B. germanica respectively (R2 = 0.78; p = 0.0001) in 1 h. KDT50 value was found to be 8.7 min (95% CI: 7.3–10.2), while KDT99 was 20.7 min (95% CI: 16.0–35.7) in P. americana at 1% concentration. Whereas, the KDT50 and KDT99 values for B. germanica were 7.4 min (95% CI: 5.4–9.1) and 27.4 min (95% CI: 18.2–80.0) at a similar concentration. LD50 and LD95 values (for 60 min standard exposure) were 0.0006% (95% CI: 0.00–0.001) and 0.034% (95% CI: 0.013–0.49) respectively for P. americana, while these values were 0.0005 (95% CI: 0.00–0.001) and 0.04 (95% CI: 0.01–0.23) for B. germanica. Exposure to 1% deltamethrin induced a considerable toxic effect in the epithelial cells in the midgut. HPLC estimated 0.21 ± 0.05 mg (95% CI: 0.18–0.25; CoV 23.9%) deltamethrin in P. americana post 1% exposure. Even short term exposure to a low concentration of synthetic pyrethroid deltamethrin displayed immediate knockdown and delayed mortality in both the test species. Considerable histological damage was observed in both the insects at 1% exposure. In India, resistance to deltamethrin may have been reported among different insects due to its extensive use. However, the formulations such as insecticide paints, attractant baits etc. developed using deltamethrin as an active ingredient could be useful in cockroach control operations.

Deltamethrin Microencapsulation in Emulsion Paint Binder and Its Long-Term Efficacy Against Dengue Vector Aedes aegypti

Various control interventions have been effective in the control of arthropod vectors to a certain extent; still, sustained vector control is an existing problem globally. Insecticide-based formulations have been found to be useful, however the proper delivery of active molecules to target vectors is important. Currently, synthetic pyrethroid deltamethrin (DM) has been microencapsulated in the emulsion paint binder and evaluated for long-term effectiveness against dengue vector Aedes aegypti. Different compositions of emulsion binder were prepared by varying the content of monomer and DM. A selection was made for the composition yielding the best combination of properties like solid content, intrinsic viscosity, and DM content. Developed formulation was tested against laboratory-reared and pathogen-free Ae. aegypti mosquitoes. Encapsulation of DM in emulsion binder during polymerization showed a uniform distribution. The optimized formulation was stable and did not have a considerable plasticizing effect. Scanning electron microscopy revealed that grain-like micro crystals of DM and surfactant sodium lauryl sulfate (SDS) were uniformly distributed on the formulation surface. The best optimized formulation was highly effective against dengue vector Ae. aegypti and found to provide efficacy for up to 18 months of application. The knockdown time (KDT) values KDT₁₀ and KDT₅₀ were 7.4 min (95% CI: 5.6–9.1) and 22.1 min (95% CI: 19.7–24.3) respectively, whereas 24 h corrected mortality was 90% (95% CI: 82.5–97.5) after 18 months of application (T18). The probit model used to determine knockdown values did not deviate from the linearity and displayed normal distribution of knockdown % with time for different formulations (p ≥ 0.1). Presently developed DM microencapsulated emulsion binder was stable, smooth, and uniform. The binder displayed excellent anti-insect property and was capable of providing long-term effectiveness against dengue vectors Ae. aegypti. Such a formulation after field-scale evaluation could be very useful in attaining long-term protection from arthropod vectors.

Behavioural response of mosquito vectors Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus to synthetic pyrethroid and organophosphorus-based slow-release insecticidal paint

BACKGROUND

The direct toxicological impact of insecticides on vector mosquitoes has been well emphasized; however, behavioural responses such as excito-repellency and physical avoidance as a result of insecticide exposure have not been much studied. We have demonstrated the excito-repellency and behavioural avoidance in certain vector mosquito species on exposure to a slow-release insecticidal paint (SRIP) formulation in addition to direct toxicity.

METHODS

A SRIP formulation developed by the Defence Research and Development Establishment, Gwalior, contains chlorpyriphos, deltamethrin and pyriproxyfen as active insecticides. Anopheles stephensi, Culex quinquefasciatus and Aedes aegypti mosquitoes were used to study the excito-repellency response of the formulation. The experiments were performed in a specially designed dual-choice exposure and escape chamber made of transparent polymethyl methacrylate. For the experiments, the SRIP formulation was applied undiluted at a rate of 8 m² per kg on 15 cm² metallic surfaces. Mosquitoes were introduced into the exposure chamber, and observations of the movement of mosquitoes into the escape chamber through the exit portal were taken at 1-min intervals for up to 30 min.

RESULTS

The evaluated formulation displayed strong excito-repellency against all three tested vector mosquito species. Results showed that the ET₅₀ (escape time 50%) for Ae. aegypti, An. stephensi and Cx. quinquefasciatus was 20.9 min, 14.5 min and 17.9 min for contact exposure (CE) respectively. Altogether in CE, the escape rates were stronger in An. stephensi mosquitoes at different time intervals compared to Ae. aegypti and Cx. quinquefasciatus mosquitoes. The probit analysis revealed that the determined ET did not deviate from linearity for both non-contact exposure (NCE) and placebo exposure (PE) (χ² ≤ 7.9; p = 1.0) for Ae. aegypti mosquitoes and for NCE (χ² = 8.3; p = 1.0) and PE (χ² = 1.7; p = 1.0) treatments in Cx. quinquefasciatus. Mortality (24 h) was found to be statistically higher (F = 6.4; p = 0.02) in An. stephensi for CE but did not vary for NCE (p ≥ 0.3) and PE (p = 0.6) treatments among the tested mosquito species. Survival probability response suggested that all the three tested species displayed similar survival responses for similar exposures (χ² ≤ 2.3; p ≥ 0.1).

CONCLUSION

The study demonstrates the toxicity and strong behavioural avoidance in known vector mosquito species on exposure to an insecticide-based paint formulation. The combination of insecticides in the present formulation will broaden the overall impact spectrum for protecting users from mosquito bites. The efficacy data generated in the study provide crucial information on the effectiveness of the tested formulation and could be useful in reducing the transmission intensity and disease risk in endemic countries.

Pyriproxyfen treated surface exposure exhibits reproductive disruption in dengue vector Aedes aegypti

Background

Reduced susceptibility of mosquito vectors to currently used insecticides hampers control interventions. Recently pyriproxyfen, an insect growth regulator has been demonstrated to effectively reduce the reproductive potential in vector mosquitoes.

Methods

Pyriproxyfen (PPF), in different concentrations (0.75%, 0.075%, 0.0075%, and 0.00075%) was applied on papers and Indian wild type Aedes aegypti female mosquitoes (N ≥ 20 for each treatment) were exposed onto it as per WHO guidelines, to study the reproductive disruption. PPF concentration on treated papers was quantitatively cross-determined using HPLC method. Reduction in fecundity, fertility and adult emergence in exposed female Ae. aegypti was determined. Abnormal development in ovary and eggs of exposed females was studied microscopically after different time intervals.

Results

Eggs laid, eggs hatched, pupae formed and adults emerged per female exposed in both before blood meal and after blood meal groups declined significantly from lowest to highest concentration of PPF (F ≥ 5.2; p < 0.02). Adult emergence inhibition in females exposed to PPF before and after blood meal groups ranged from 58.8% [OR = 0.18 (95% CI = 0.09–0.36)] to 79.2% [OR = 0.04 (95% CI = 0.02–0.10)] and 64.4% [OR = 0.12 (95% CI = 0.05–0.28)] to 77.1% [OR = 0.05 (95% CI = 0.02–0.14)] respectively in different concentrations. The probit model used suggested that FI₅₀ (50% fertility inhibition) and EI₅₀ (50% emergence inhibition) were 0.002% (p = 0.82) and 0.0001% (p = 0.99) for females exposed before blood meal, while 0.01% (p = 0.63) and <0.0001% (p = 0.98) for the females exposed after blood meal, respectively. The eggs laid by the females exposed to PPF-treated surface showed altered body organization, desegmentation and disoriented abdominal and cervical regions in the developing embryo. Quantification of PPF on impregnated papers showed that it was uniformly distributed throughout the matrix.

Conclusions

The present study has shown that tarsal contact to PPF-treated surface for a small time drastically influenced the fecundity, fertility and adult emergence in Indian wild Ae. aegypti mosquitoes. Results suggest that a certain minimum concentration of PPF through contact exposure can reduce the abundance of vector mosquitoes to a considerable level. The formulations based on combination of PPF and other compatible insecticides may be an impactful approach where susceptible mosquitoes are killed by the insecticide component while resistant mosquitoes are sterilised by PPF.

Development of resistance against insecticides has challenged mosquito control programmes globally and prompted the research of alternative options that can complement insecticides. An insect growth regulator, pyriproxyfen (PPF) usage against mosquitoes can effectively reduce the vector population. PPF mainly inhibits the metamorphosis of mosquito larvae into pupae and prevent the adult emergence, therefore it is generally applied in mosquito breeding habitats. PPF has been shown to exhibit delayed residual effect that may impair the reproductive capacity by affecting the survival, fecundity and fertility of adult mosquito exposed through tarsal contact. Presently, the effectiveness of different concentrations of PPF intended to be delivered through contact have been evaluated against dengue vector Ae. aegypti. Results suggested that very low PPF concentration treated surfaces drastically reduce the fecundity, fertility and adult emergence in mosquitoes. Study suggests that control interventions based on PPF-treated surfaces could provide an additional route to target mosquito vector control by overall population density reduction.

Correction to: Are malaria elimination efforts on right track? An analysis of gains achieved and challenges ahead

AbstractIn the original publication of this article [1], the legends in Fig. 9 are missing during the process of typesetting.

Are malaria elimination efforts on right track? An analysis of gains achieved and challenges ahead

Background

Malaria causes significant morbidity and mortality each year. In the past few years, the global malaria cases have been declining and many endemic countries are heading towards malaria elimination. Nevertheless, reducing the number of cases seems to be easy than sustained elimination. Therefore to achieve the objective of complete elimination and maintaining the elimination status, it is necessary to assess the gains made during the recent years.

Main text

With inclining global support and World Health Organisation (WHO) efforts, the control programmes have been implemented effectively in many endemic countries. Given the aroused interest and investments into malaria elimination programmes at global level, the ambitious goal of elimination appears feasible. Sustainable interventions have played a pivotal role in malaria contraction, however drug and insecticide resistance, social, demographic, cultural and behavioural beliefs and practices, and unreformed health infrastructure could drift back the progress attained so far. Ignoring such impeding factors coupled with certain region specific factors may jeopardise our ability to abide righteous track to achieve global elimination of malaria parasite. Although support beyond the territories is important, but well managed integrated vector management approach at regional and country level using scrupulously selected area specific interventions targeting both vector and parasite along with the community involvement is necessary. A brief incline in malaria during 2016 has raised fresh perturbation on whether elimination could be achieved on time or not.

Conclusions

The intervention tools available currently can most likely reduce transmission but clearing of malaria epicentres from where the disease can flare up any time, is not possible without involving local population. Nevertheless maintaining zero malaria transmission and checks on malaria import in declared malaria free countries, and further speeding up of interventions to stop transmission in elimination countries is most desirable. Strong collaboration backed by adequate political and financial support among the countries with a common objective to eliminate malaria must be on top priority. The present review attempts to assess the progress gained in malaria elimination during the past few years and highlights some issues that could be important in successful malaria elimination.

Electronic supplementary material

The online version of this article (10.1186/s40249-019-0524-x) contains supplementary material, which is available to authorized users.

Self-Transport and Manipulation of Aqueous Droplets on Oil-Submerged Diverging Groove

We report experimental study of self-transport of aqueous droplets along an oil-submerged diverging groove structure. The migration phenomenon is illustrated, and the effect of various parameters such as droplet size d, oil layer thickness h, groove angle 2θ, and groove thickness δ on the droplet transport behavior (i.e., migration velocity and length) is investigated. Our study reveals that complete engulfment of aqueous droplets in the oil layer, that is attributed to a positive spreading parameter ( S > 0), is a prerequisite for the droplet transport. The results show that only droplets of diameter larger than the oil layer thickness (i.e., d ≥ h) get transported owing to a differential Laplace pressure between the leading and trailing faces of a droplet because of the diverging groove. Using experimental data, the variation of droplet migration velocity with distance along the diverging groove is correlated as U( x) = ψ x^-0.9, where ψ = d^0.32θ^-2.2 h^-1.5δ^0.7. The submerged groove structure was used to demonstrate simultaneous and sequential coalescence and transport of multiple droplets. Finally, the submerged groove structure was employed for extraction of aqueous droplets from oil. The proposed technique opens up a new avenue for evaporation and contamination free transport and coalescence of droplets for chemical and biological applications.

Cerebral organoids reveal early cortical maldevelopment in schizophrenia-computational anatomy and genomics, role of FGFR1

Studies of induced pluripotent stem cells (iPSCs) from schizophrenia patients and control individuals revealed that the disorder is programmed at the preneuronal stage, involves a common dysregulated mRNA transcriptome, and identified Integrative Nuclear FGFR1 Signaling a common dysregulated mechanism. We used human embryonic stem cell (hESC) and iPSC-derived cerebral organoids from four controls and three schizophrenia patients to model the first trimester of in utero brain development. The schizophrenia organoids revealed an abnormal scattering of proliferating Ki67+ neural progenitor cells (NPCs) from the ventricular zone (VZ), throughout the intermediate (IZ) and cortical (CZ) zones. TBR1 pioneer neurons and reelin, which guides cortico-petal migration, were restricted from the schizophrenia cortex. The maturing neurons were abundantly developed in the subcortical regions, but were depleted from the schizophrenia cortex. The decreased intracortical connectivity was denoted by changes in the orientation and morphology of calretinin interneurons. In schizophrenia organoids, nuclear (n)FGFR1 was abundantly expressed by developing subcortical cells, but was depleted from the neuronal committed cells (NCCs) of the CZ. Transfection of dominant negative and constitutively active nFGFR1 caused widespread disruption of the neuro-ontogenic gene networks in hESC-derived NPCs and NCCs. The fgfr1 gene was the most prominent FGFR gene expressed in NPCs and NCCs, and blocking with PD173074 reproduced both the loss of nFGFR1 and cortical neuronal maturation in hESC cerebral organoids. We report for the first time, progression of the cortical malformation in schizophrenia and link it to altered FGFR1 signaling. Targeting INFS may offer a preventive treatment of schizophrenia.

Dynamics of a Water Droplet over a Sessile Oil Droplet: Compound Droplets Satisfying a Neumann Condition

We report the dynamics of compound droplets with a denser liquid (water) droplet over a less dense sessile droplet (mineral oil) that satisfies the Neumann condition. For a fixed size of an oil droplet, depending on the size of the water droplet, either it attains the axisymmetric position or tends to migrate toward the edge of the oil droplet. For a water droplet-to-oil droplet at volume ratio V_w/V_o ≥ 0.05, stable axisymmetric configuration is achieved; for V_w/V_o < 0.05, migration of water droplet is observed. The stability and migration of water droplets of size above and below critical size, respectively, are explained using the force balance at the three-phase contact line and film tension. The larger and smaller droplets that initially attain the axisymmetric position or some radial position, respectively, evaporate continuously and thus migrate toward the edge of the oil droplet. The radial location and migration of the water droplets of different initial sizes with respect to time are studied. Experiments with water droplets on a flat oil-air interface did not show migration, which signified the role of the curved oil-air interface for droplet migration. Finally, coalescence of water droplets of size above the critical size at the axisymmetric position is demonstrated. Our compound droplet studies could be beneficial for applications involving droplet transport where contamination due to direct contact and pinning of droplets on solid surfaces is of concern. Migration and coalescence of water droplets on curved oil-air interfaces could open new frontiers in chemical and biological applications including multiphase processing and biological interaction of cells and atmospheric chemistry.

Morphometric and morphological appraisal of the eggs of Anopheles stephensi (Diptera: Culicidae) from India

BACKGROUND & OBJECTIVES

Anopheles stephensi is one of the most important urban malaria vectors in India and contribute about 12% of total malaria cases. An. stephensi has three ecological variants; type, intermediate and mysorensis that can be differentiated on the basis of differences in number of ridges on egg float and on the basis of spiracular indices. Because of its anthropophilic nature the 'type' form is an efficient malaria vector. In the present study, the egg surface morphometry and morphology of An. stephensi 'type' form was studied and detail distinguish- ing characters were recorded for its correct identification.

METHODS

Eggs of An. stephensi 'type' form were studied by scanning electron microscopy (SEM) after sputter- coating with gold. In total 23 egg characters were analysed morphologically and morphometrically, which included egg attributes, deck attributes, ventral tubercles, micropyle and float attributes.

RESULTS

The dorsal surface of the egg of 'type' form was curved while the ventral surface was concave and both anterior and posterior ends were blunt. The average length and width of egg was 473.94 + 11.18 and 154.69 + 2.66 μm respectively. The number of float ribs observed was 20.33 ± 0.33. The maximum length of float was found to be 246.57 + 15.27 μm, whereas maximum width was 87.16 + 3.83 μm.

INTERPRETATION & CONCLUSION

The present study has generated some important data which is specific to An. Stephensi 'type' form and provided significant morphological and morphometric standards for its correct identification. This information could be useful in differentiation of An. stephensi 'type' form from other ecological forms of the same species as well as other species of Anopheles.

Disappearance of Anopheles minimus and Anopheles dirus from Certain Malaria Endemic Areas of Assam, India

BACKGROUND

Orang Primary Health Centre (OPHC) and Balipara Primary Health Centre (BPHC) of Assam (India) report mosquito borne diseases annually. Current study was performed to ascertain the prevalence of known malaria and Japanese Encephalitis (JE) vectors and their possible role in disease transmission.

METHODS

Malaria epidemiological data for 2006-2010 and JE data for 2008-2013 of Assam, India were obtained from the health authority. Mosquitoes were collected using CDC light traps and identified morpho-taxonomically.

RESULTS

Plasmodium falciparum cases (81.5%, 95% CI= 72.0-91.1) were statistically higher in OPHC (P< 0.0001, t= 8.0) during the recent years. There was 4.4 folds rise in the confirmed acute encephalitis syndrome (AES) and 3.2 folds increase in the confirmed JE cases during 2013 as compared to 2008. Altogether 9,218 mosquito specimens (PTND= 153.6), comprising of 44.1% anophelines (PTND= 67.7), 42.3% culicines (PTND= 65.0) and 9.5% mansonia (PTND= 14.6) were recorded. In BPHC, Anopheles vagus was recorded in high density (P< 0.0001), whereas Culex quinquefasciatus was the predominant JE vector (P= 0.04). In OPHC, among the known malaria vectors, the density of Anopheles annularis was significantly high (P< 0.0001). However Culex bitaeniorhynchus was the predominant known JE vector (P< 0.0001) followed by Cx. quinquefasciatus.

CONCLUSION

Even in the absence of known efficient vectors, many Anopheles species are still involved in malaria transmission. There was disappearance of Anopheles minimus and Anopheles dirus and establishment of An. annularis, An. vagus and An. philippinensis/nivipes mosquitoes in study area.

Novel Bio-Markers for Prediction of Preeclampsia

Pre-eclampsia (PE) is a pregnancy related disorder. It is an important cause of maternal and perinatal morbidity and mortality worldwide. Two to eight percent of pregnancies were affected by PE. It is characterized by de novo hypertension and proteinuria after 20 weeks of gestation. The etiology and pathogenesis of the disease is unknown, but recent studies have revealed that placenta is the place of origin of this disorder and widespread maternal endothelial dysfunction is the characteristic feature of the disease. Some biochemical molecules are identified recently which are involved in the pathogenesis of the disease, which may help in early identification of patients at risk and help in providing proper prenatal care. Several promising biomarkers have been proposed, alone or in combination. Maternal serum concentrations of these biomarkers either increase or decrease in PE during gestation. This review focuses on the various biomarkers available and their utility in prediction and diagnosis of pre-eclampsia.

Typing of Plasmodium falciparum DNA from 2 years old Giemsa-stained dried blood spots using nested polymerase chain reaction assay

A panel of 129 Giemsa-stained thick blood spots (TBS) confirmed for Plasmodium falciparum infection having different levels of parasite density were collected from a malaria endemic area. DNA was extracted and nested polymerase chain reaction (PCR) assay was performed to amplify P. falciparum DNA. Nested PCR assay successfully amplified P. falciparum DNA at a very low parasitaemia of ~10 parasites/μl of blood. Current PCR assay is very simple and can be used retrospectively to monitor the invasion and prevalence of different Plasmodium species in endemic areas.

Malaria vector Anopheles culicifacies sibling species differentiation using egg morphometry and morphology

Background

The malaria vector Anopheles culicifacies (sensu lato) is an important malaria vector in Southeast Asia which comprises of five sibling species namely A, B, C, D and E. However, only a few forms have been identified as malaria vectors in various endemic countries. Currently, for the first time egg morphometry and morphology has been used to differentiate the three known vector sibling species of Anopheles culicifacies collected from malaria endemic Madhya Pradesh state of central India.

Methods

The adult An. culicifacies (s.l.) was collected from five districts using standard mosquito collection methods. Adult female mosquitoes were allowed to lay eggs individually. The emerged mosquitoes were identified using allele specific polymerase chain reaction (AS-PCR) to sibling species. Eggs of sibling species A, D and E were studied using scanning electron microscopy (SEM) for morphometric and morphological characteristics.

Results

Currently AS-PCR identified four known sibling species (B, C, D and E) of An. culicifacies in the study area. The surface morphology and morphometric attributes of the sibling species A, D and E eggs considerably differed from each other. An. culicifacies E had a narrow deck as compared to A and D, while An. culicifacies A had a bigger micropyle with 6–7 sectors as compared to D and E that had 6 sectors. An. culicifacies D had the smallest float (the structure present on sides of the egg surface in which air is filled that help in floating) and the number of ribs was also fewer than for An. culicifacies A and E.

Conclusions

The present study provides the first evidence that in addition to PCR assay, sibling species of An. culicifacies can also be differentiated using morphological and morphometric characteristics of the egg stage. The results also advocate that the sibling species of An. culicifacies are morphologically dissimilar and can be resolved using advanced microscopy.

Preliminary in vitro antiplasmodial activity of Aristolochia griffithii and Thalictrum foliolosum DC extracts against malaria parasite Plasmodium falciparum

Background

Resistance development in human malaria parasites against commonly used antimalarial drugs has necessitated the scientific exploration of traditionally used antimalarial plants. Plant derivatives have been used for curing malaria historically. The present study involves in vitro evaluation of two medicinally important plants Aristolochia griffithii and Thalictrum foliolosum DC used in antimalarial chemotherapy by the tribes of northeast India.

Method

Chloroform, ethyl acetate and n–butanol extracts of Aristolochia griffithii and Thalictrum foliolosum DC were evaluated in vitro against chloroquine sensitive (SS) and chloroquine resistance strains (RS) of P. falciparum. The tests were conducted following WHO standard method and the inhibition of parasite (IC₅₀) was calculated.

Results

In A. griffithii, the IC₅₀ value for ethyl acetate extracts against SS was 6.2 ± 0.02 μg/ml and found to be lower than chloroform extracts, which exhibited an IC₅₀ value of 14.1 ± 0.1 μg/ml (t = 191.1; p < 0.0001). The IC₅₀ values of both chloroform and ethyl acetate extracts for RS were higher as compared to the SS (p < 0.0001). In T. foliolosum DC the IC₅₀ concentration of chloroform extracts for SS and RS were 0.5 ± 0.0 and 1.1 ± 0.0 μg/ml respectively (t = 54.2; p < 0.0001).

Conclusion

The present findings, although preliminary, but scientifically demonstrate that identification and isolation of active compounds of these two plant materials and testing against different Plasmodium species could lead to the development of potential antimalarial drugs for future.

Absence of asymptomatic malaria in a cohort of 133 individuals in a malaria endemic area of Assam, India

BACKGROUND

Malaria in northeast India affects children and adults annually. The number of malaria cases reported has declined over the past few years. Nevertheless, it is not clear whether there is an actual decline in parasitaemia or whether asymptomatic malaria infections are on the rise, especially in forested and forest-fringed areas. Asymptomatic malaria forms a parasite reservoir that acts as an epicentre for malaria spread during high-transmission season. Therefore it is important to understand the quantum of asymptomatic malaria infections among the vulnerable population.

METHOD

Four forest fringed historically malaria endemic villages were selected for the study. A total of 133 individuals without a fever history in the past four weeks were tested for malaria parasite using rapid diagnostic test (RDT), microscopy and polymerase chain reaction (PCR) assay during January - February 2014. Indoor resting Anopheles vectors were collected, identified and tested for sporozoite using VectorTest™ panel assay during October 2013 to March 2014, which is a low transmission season for malaria. Social and demographic data were recorded during the study.

RESULTS

Mean age (± SEM) of the participants was 16.1 ± 1.2 years (95 % CI: 13.8-18.4). All participants (100 %) reported to use mosquito nets. Altogether, 43.6 % of participants had education below primary level and only 9 % reported a travel history during the past four weeks. All RDT, microscopy and PCR assays were found negative indicating no asymptomatic malaria parasitaemia. Seven known malaria vector species namely, Anopheles nivipes, An. minimus, An. annularis, An. vagus, An. aconitus, An. philippinensis and An. culicifacies, were recorded in the present study. VectorTest™ sporozoite panel assay conducted on 45 pools (N = 224) of vector mosquitoes were found negative for Plasmodium sporozoite.

DISCUSSION

Northeastern states of India report asymptomatic malaria parasitemia along with high malaria transmission. An. minimus and An. dirus are recognised as efficient vectors, but An. culicifacies, An. philippinensis and An. annularis also play role in malaria transmission. Currently all participants were found negative for asymptomatic malaria, however the small sample size may restrict the scope of present results to the population living in more remote areas.

CONCLUSION

No cases of asymptomatic malaria infections parasitaemia was found in the present study conducted during a low transmission season indicating that asymptomatic malaria parasitaemia may not be prevalent in the region. Mosquito specimens were tested negative for the malaria sporozoites. Study findings encourage the ongoing malaria intervention efforts and recommends similar investigations in different ecological areas involving large populations.

Essential oil based polymeric patch development and evaluating its repellent activity against mosquitoes

Essential oil based insect repellents are environment friendly and provide dependable personal protection against the bites of mosquitoes and other blood-sucking insects. In the present study, optimized mixture of three essential oils was embedded into the ethylcellulose (EC) and polyvinylpyrrolidone (PVP K-30) polymers to develop essential oils based patch type mosquito repellent formulation. The developed formulation was characterized for various physico-chemical properties, oil release efficiency and essential oil-polymer interaction. Repellent activity of the formulation was evaluated against Ae. (S) albopictus mosquitoes and compared with commercially available synthetic insecticide based mosquito repellent cream Odomos(®) in the laboratory. The developed patches were 100% flat and there was no interaction between oil components and the excipients. Patches were smooth, homogenous and provided excellent mosquito repellent activity comparable to Odomos(®) under laboratory condition. Morphological and physico-chemical characterization indicated that the formulation was stable and suitable with the polymeric combination. The patch formulation did not show any inhalation toxicity in experimental Wistar rat. The repellent patches developed and evaluated currently, may provide a suitable, eco-friendly, acceptable and safe alternative to the existing synthetic repellent formulations for achieving protection against mosquitoes.

Synergistic mosquito-repellent activity of Curcuma longa, Pogostemon heyneanus and Zanthoxylum limonella essential oils

Mosquito repellents play an important role in preventing man-mosquito contact. In the present study, we evaluated the synergistic mosquito-repellent activity of Curcuma longa, Pogostemon heyneanus and Zanthoxylum limonella essential oils. The mosquito repellent efficacies of three essential oils were evaluated separately and in combination under laboratory and field conditions. N,N-Diethylphenylacetamide (DEPA) and dimethylphthalate (DMP) were used for comparison of the protection time of the mixture of essential oils. At an optimum concentration of 20%, the essential oils of C. longa, Z. limonella and P. heyneanus provided complete protection times (CPTs) of 96.2, 91.4 and 123.4 min, respectively, against Aedes albopictus mosquitoes in the laboratory. The 1:1:2 mixture of the essential oils provided 329.4 and 391.0 min of CPT in the laboratory and field trials, respectively. The percent increases in CPTs for the essential oil mixture were 30 for DMP and 55 for N,N-diethylphenylacetamide (DEPA). The synergistic repellent activity of the essential oils used in the present study might be useful for developing safer alternatives to synthetic repellents for personal protection against mosquitoes.

Multi-insecticide susceptibility evaluation of dengue vectors Stegomyia albopicta and St. aegypti in Assam, India

BACKGROUND

Dengue is rapidly expanding mosquito-borne viral infection globally facing operational challenges due to insecticide resistance in dengue vectors. We have studied the susceptibility status of potential dengue vectors St. albopicta and St. aegypti to the commonly used insecticides.

METHODS

Stegomyia larval bioassays were carried out to determine LC10, LC50 and LC99 values and resistance ratios (RR50 and RR99) for temephos. Adult susceptibility bioassay to 4% DDT, 0.05% deltamethrin, 5% malathion was assessed following standard procedure to determine the corrected mortality. Knock-down times (KDT50 and KDT99) were estimated and the knock-down resistance ratios (KRR50 and KRR99) were calculated.

RESULTS

St. albopicta wild population (WP) of Sotia was resistant to temephos as the LC99 value was 0.12 mg/l and found to be 2.3 fold high than the reference population (RP). St. aegypti WP of Borgong, Kusumtola and Serajuli displayed a RR99 of 2.5, 5.4 and 4.5 respectively suggesting high level of resistance to temephos. Results suggested that both St. albopicta and St. aegypti WP were fully resistant to DDT (mortality < 90%) in all the study locations. Both the species were completely susceptible to deltamethrin and malathion (corrected mortality > 98%), except for St. albopicta at Sotia which displayed low level of resistance to malathion (corrected mortality =95.4%). The estimated KDT values for both the species indicated high level of knock-down resistance to DDT and susceptibility to deltamethrin.

CONCLUSION

WP of both the dengue vectors showed varied response to temephos, while resistant to DDT and completely susceptible to deltamethrin. Both the species were susceptible to malathion at majority of the testing sites. Current results strongly advocate that DDT is no longer effective against dengue vectors, while thorough monitoring of malathion susceptibility in geographical area at dengue risk is inexorable to ascertain whether or not the resistance to malathion is focal. Information generated herein may be useful in better planning and implementing in dengue control strategy using insecticides.

Role of asymptomatic carriers and weather variables in persistent transmission of malaria in an endemic district of Assam, India

Background

Malaria transmission is perennial in the Assam–Arunachal Pradesh interstate border areas in the Sonitpur district of Assam, India. A yearlong study was carried out on the incidence of symptomatic and asymptomatic malaria and the role of asymptomatic malaria carriers in persistent transmission of the disease. The relationships between malaria incidence and weather parameters were also investigated.

Methods

Active and mass blood surveys were conducted on a monthly basis in Bengenajuli, Sapairaumari Pathar, and Nigam villages near the Assam–Arunachal Pradesh border. Epidemiological indices were estimated for malaria-positive cases. Multiple linear regression between monthly malaria incidence and monthly average temperature, and relative humidity along with monthly total rainfall was carried out. The known malaria vectors collected in CDC light traps were identified and recorded.

Results

Slide positivity rate (SPR) and Plasmodium falciparum percent (Pf%) for symptomatic malaria were 26.1 and 79.8, respectively. Prevalence of malaria vectors was observed throughout the year with varying density. Anopheles philippinensis/nivipes and A. annularis were predominant among the seven known vector species recorded currently. Asymptomatic parasitemia was detected throughout the year with SPR ranging from 4.8 to 5.3. Monthly rainfall with 1-month lag had the highest correlation (r=0.92) with SPR. The relationship between SPR and weather factors was established as SPR=−114.22+0.58 T_min+1.38 RH+0.03 RF (R²=0.89; p=0.00).

Conclusion

Low and relatively constant levels of asymptomatic parasitemia was present in the study area. High malaria vector density and presence of asymptomatic malaria parasite carriers were responsible for persistent malaria transmission in the region. This study concludes that passive detection and prompt treatment of asymptomatic carriers is essential for preventing persistent disease transmission. Rainfall along with some other weather variables may be used for predicting the malaria epidemics in the region. The predictive information could be useful to target resources more effectively.

Genetic polymorphism and amino acid sequence variation in Plasmodium falciparum GLURP R2 repeat region in Assam, India, at an interval of five years

Background

The R2 repeat region of GLURP has been reported as a good genetic marker for Plasmodium falciparum genotyping. Proper knowledge of the extent and nature of P. falciparum genetic diversity using highly immunogenic R2 repeat region in malaria-endemic areas is a crucial element to understand various aspects related to immunity acquisition and disease pathogenesis.

Methods

Population diversity of P. falciparum GLURP and amino acid sequence repeats in GLURP R2 region was studied in malaria-endemic Assam state, northeast India and compared at an interval of five years during 2005 (Group-A) and 2011 (Group-B).

Results

Of the 66 samples, a total of 55 samples showed positive PCR bands for GLURP R2 region and altogether ten types of alleles with size ranging from 501 bp to 1,050 bp (50 bp bin) were observed and coded as genotypes I-X. In Group-A (n = 29), 24 samples were found infected with single, four with double and one with triple P. falciparum genotype, while in Group-B (n = 26), single genotype was found in 23 samples, double in two samples and triple in one sample. Genotype IV showed significant increase (p = 0.002) during 2011 (Group-B). Genotypes I to V were more common in Group-B (62%), however genotypes VI to X were more frequently distributed in Group-A. The expected heterozygosity was found slightly higher in Group-A (H_E = 0.87) than Group-B (H_E = 0.85), whereas multiplicity of infection (MOI) in Group-A (MOI = 1.21 ± 0.49) and Group-B (MOI = 1.12 ± 0.43) did not display significant variation. The amino acid repeat sequence unit (AAU) DKNEKGQHEIVEVEEILPE (called ‘a’) was more frequent in the well-conserved part of R2 repeat region.

Conclusion

The present study is the first extensive study in India which has generated substantial data for understanding the type and distribution of naturally evolved genetic polymorphism at amino acid sequence level in GLURP R2 repeat region in P. falciparum. There was decrease in the PCR amplicon size as well as the number of AAU [amino acid repeat unit] in Group-B displaying the bottleneck effect. The present study described a new type of AAU ‘d’ which varied from the other previous known AAUs.

Electronic supplementary material

The online version of this article (doi:10.1186/1475-2875-13-450) contains supplementary material, which is available to authorized users.

High prevalence of pfcrt K76T and mdr1 N86Y mutations in Sonitpur district of Assam, India

Present study reports the prevalence and distribution of pfcrt K76T and mdr1 N86Y mutations in malaria endemic areas of Sonitpur district of Assam. Out of 163 individuals tested for malaria, 67 (SPR = 41.1 %) were detected positive for malaria infection using rapid detection kit in the field and PCR assay in the laboratory. Nested PCR-RFLP assay was used to amplify pfcrt K76T and mdr1 N86Y genes flanking the K76T and N86Y mutations. P. falciparum was most abundant (91.04 %) among the three Plasmodium species reported and its prevalence was significantly higher as compared to P. vivax and P. malariae (χ(2) = 150.76; p ≤ 0.0001; df = 2). Malaria was equally distributed among all the age groups and both the sexes. Hemoglobin contents in severe anaemic patients had a significant linear decreasing trend among patients with the increase in age (χ(2) = 4.33; p = 0.03), whereas non severe anaemic patients exhibited significant linear increasing trend among the patients with the increase in age (χ(2) = 18.38; p ≤ 0.0001). Pfcrt K76T mutation was recorded in 44 (72.13 %) isolates, whereas mdr1 N86Y mutation could be detected in 28 (41.79 %) isolates only. Only 32.7 % of the samples had both pfcrt K76T and mdr N86Y mutations. Number of pfcrt K76T mutant isolates was significantly higher than the wild type. However no significant difference was observed among the number of isolates with mdr1 N86Y mutant and wild isolates.

Insecticide susceptibility and dengue vector status of wild Stegomyia albopicta in a strategically important area of Assam, India

BACKGROUND

Dengue vector control programmes are facing operational challenges due to resistance against commonly used insecticides throughout the endemic countries. Recently, there has been appreciable increase in the dengue cases in India, however, no recent data are available on susceptible status of dengue vectors. We have studied the susceptibility level of St. albopicta to commonly used insecticides in India. Adult mosquitoes were tested for the presence of dengue virus.

METHODS

St. albopicta larval bioassays were carried out to determine the lethal concentrations (LC10, LC50 and LC99) and the resistance ratios (RR10, RR50 and RR99) for temephos. Susceptibility to 4% DDT, 0.05% deltamethrin and 5% malathion was assessed following standard procedure. Knock-down times (KDT10, KDT50 and KDT99) were estimated and knock-down resistance ratios (KRR10, KRR50 and KRR99) were calculated. VectorTest™ dengue antigen assay was used to detect the dengue virus in the field collected mosquitoes.

RESULTS

In larval bioassays, the RR ranged from 1.4 (for RR99) to 1.7 (for RR50), which suggested that the tested St. albopicta were susceptible to temephos. There was no deviation among the lethal concentration data from linearity (r2=0.61). Adult St. albopicta mosquitoes were resistant to DDT, while fully susceptible to deltamethrin and malathion. The knock-down values (KDT10, KDT50 and KDT99) obtained for DDT displayed straight line in log-dose-probit analysis and follow linear regression model. The KRR99 for DDT was 4.9, which indicated a 4.9 folds increase in knock-down resistance to DDT. However, for malathion and deltamethrin, the KRR99 values were 1.6 and 1.5 respectively suggesting that mosquitoes were knock-down sensitive. None of the mosquito pool was dengue virus positive.

CONCLUSION

St. albopicta showed resistance to DDT and reduced sensitivity to deltamethrin and malathion. This data on insecticide resistance could help public health authorities in India to design more effective vector control measures. More dengue vector specimens need to be scanned to identify the potential dengue vector.

Socio-economic determinants for malaria transmission risk in an endemic primary health centre in Assam, India

Background

Malaria is a major cause of morbidity and mortality in Northeast India. As there is limited information available on the potential influence of socio-economic variables on malaria risk, the present study was conducted to assess the influence of demographic factors, the socio-economic status, and knowledge, awareness and education on malaria occurrence.

Methods

Demographics, malaria knowledge and socio-economic variables were collected in four randomly selected health sub-centres of the Orang primary health centre in the Udalguri district, Assam and the association of malaria occurrence with different variables were analysed. The trend of malaria occurrence for different income groups, proximity to health centres and number of mosquito bites per day was also determined using the chi-square test. Relative risk (RR) for gender, house type, knowledge and use of bed nets was determined using Katz approximation.

Results

Out of the 71 household heads interviewed, 70.4% (50/71) were males. About half (54.9%, 39/71) of the participants had a history of malaria in the last two years, of which 64.1% (25/39) were males, while 35.9% (14/39) were females (χ² = 5.13; p = 0.02; RR = 1.79). Of the total population surveyed, 49.3% lived in bamboo houses and 35.2% lived at a distance of >3 km from the nearest health centre. The number of participants who had a history of malaria decreased with an increasing monthly income (p < 0.0001). Malaria occurrence was higher among the households living in bamboo houses (69.2%), as compared to Kucha houses (20.5%) and Pucca houses (10.3%). No significant association was observed between education level and malaria occurrence (p = 0.93). The participants who did not use bed nets regularly reported a high occurrence of malaria infection as compared to those who used bed nets everyday (p < 0.0001).

Conclusions

Lower income, house type, distance to health sub-centre, knowledge and awareness about malaria, number of mosquito bites per day and use of bed nets were positively associated with malaria occurrence. Increasing the number of health sub-centres close to rural areas, improving the economic status and increasing awareness about malaria prevention measures will thus help to reduce malaria-associated morbidities.

Pfcrt mutant haplotypes may not correspond with chloroquine resistance

INTRODUCTION

Chloroquine resistance in Plasmodium falciparum is associated with mutations in pfcrt and pfmdr1 genes. The frequency distribution of pfcrt K76T and pfmdr1 N86Y mutations and their association with chloroquine susceptibility was studied in an endemic area along the Indo-Bangladesh border.

METHODOLOGY

A single-arm prospective study of clinical and parasitological responses in P. falciparum malaria patients to chloroquine was conducted in vivo. PCR-RFLP assay was used to detect pfcrt K76T and pfmdr1 N86Y mutations in P. falciparum. The PCR products of pfcrt gene were sequenced,  translated and aligned for haplotyping.

RESULTS

Out of 63 cases, 44 (69.8%) responded adequately to chloroquine treatment. Pfcrt K76T mutation was recorded in 100% of the treatment failure cases, whereas pfmdr1 N86Y mutation was found in 52.6% of the cases only. Early treatment failure (84.2%) occurred more frequently than late treatment failure (15.8%). Kaplan-Meier survival analysis showed that the probability estimate for treatment success after 7 and 15 days was 0.84 (95% CI = 0.72-0.92) and 0.70 (95% CI = 0.57-0.80), respectively. Sequence analysis of 72 to 76 pfcrt gene codons revealed the presence of two mutant (CVMNT, CVIET) and two wild (CVMNK, CVIEK) haplotypes. The mutant CVIET haplotype was predominantly distributed (42.1%).

CONCLUSIONS

The presence of mutations in pfcrt K76T and pfmdr1 N86Y genes is not sufficient to explain the therapeutic efficacy of chloroquine to P. falciparum. Study suggests that pfcrt K76T mutant haplotypes are widely distributed and are spreading diligently, which needs to be taken into account in devising an antimalarial policy.

Black fly (Simulium sp) composition, daytime biting activity and possible onchocerciasis infection in north-east, India

Pupal stages of Simulium were collected and identified from various breeding habitats of twelve locations in northeastern India. Simulium flies, while attempting to land on human were collected between 07:00-17:00 hrs to understand the biting pattern. Seven species belonging to three sub-genera, Eusimulium (1), Gomphostilbia (1) and Simulium (5) belonging genus Simulium were encountered. Out of total seven species recorded, S. (E) aureohirtum, S. (G) tenuistylum and S. (S) rufibasis were predominant and shared 30.3%, 29.9% and 27.6% of total collection. Stream breeding habitat contributed 47.3% of total catch and was found to be preferred breeding habitat (p < 0.0001). S. (S) christophersi and S. (G) tenuistylum were recorded for the first time from the northeastern region of India. Simuliids biting rhythm showed bimodal pattern and were more active during sunny day (p < 0.0001). Microscopic dissection of simuliids (n = 266) did not incriminate simuliids as vector of onchocerciasis.

Nested PCR detection of Plasmodium malariae from microscopy confirmed P. falciparum samples in endemic area of NE India

The present study evaluates the performance of OptiMAL-IT test and nested PCR assay in detection of malaria parasites. A total of 76 randomly selected blood samples collected from two malaria endemic areas were tested for malaria parasites using microscopy and OptiMAL-IT test in the field. PCR assays were performed in the laboratory using DNA extracted from blood spots of the same samples collected on the FTA classic cards. Of the total of 61 field confirmed malaria positive samples, only 58 (95%) were detected positive using microscopy in the laboratory. Sensitivity, specificity, positive predictive value, negative predictive value and false discovery rate of OptiMal-IT in comparison to the microscopy were 93%, 83%, 95%, 79% and 5%, respectively. On the other hand, the sensitivity and specificity of PCR assay were 97% and 100%, respectively, whereas positive predictive value, negative predictive value and false discovery rate were 100%, 90% and 0%, respectively. The overall performance of OptiMal-IT and PCR assays for malaria diagnosis was 76% and 97%, respectively. PCR assay enabled the identification of infection with Plasmodium malariae Laveran, 1881 in four samples misidentified by microscopy and Plasmodium-specific antigen (PAN) identified by the OptiMAL-IT test. In addition to the standard methods, such PCR assay could be useful to obtain the real incidence of each malaria parasite species for epidemiological perspectives.

DDT & deltamethrin resistance status of known Japanese encephalitis vectors in Assam, India

BACKGROUND & OBJECTIVE

Japanese encephalitis (JE) outbreaks are common in Assam, northeastern State of India. Information on resistance in known JE vectors in the affected area is important for effective control measures. This study was undertaken to determine the species abundance of JE vectors endemic to Sibsagar district of Assam, and their susceptibility against DDT and deltamethrin.

METHODS

Adult mosquitoes were collected using CDC light trap and aspirators from human dwellings from 13 endemic villages falling under three Primary Health Centres. Collected mosquitoes were identified and unfed female mosquitoes were used for DDT and deltamethrin sensitivity bioassay. The bioassay was performed following WHO protocol using standard susceptibility test kit. Knockdown time (KDT) was monitored at every 10 minutes intervals, whereas mortalities were recorded 24 h post-exposure. Vector density and resistance status were mapped using geographic information system (GIS) technique.

RESULTS

A total of 7655 mosquitoes were sampled under three genera, i.e. Anopheles, Culex and Mansonia, and nine species, the JE vector Cx. vishnui group (31.78%) was the most predominant species, followed by Ma. uniformis (16.81%) and Ma. indiana (16.45%). All vector species were suspected to be resistant to DDT and sensitive to deltamethrin, except Ma. indiana, which was suspected to deltamethrin resistant. The KDT50 and KDT95 values of vector mosquitoes for DDT were significantly higher as compared to deltamethrin. The probit model used to estimate KDT50 and KDT95 values did not display normal distribution of percentage knockdown with time for all the vectors tested for DDT and deltamethrin, except for Ma. indiana for deltamethrin assay and Cx. gelidus for the DDT assay.

INTERPRETATION & CONCLUSION

Differences in insecticide resistance status were observed between insecticides and vector species. The results of this study provided baseline data on insecticide resistance in known JE vectors of Sibsagar, Assam. The maps generated may allow better communication in control operations and comparison of changes in susceptibility status of these vectors over time.

Ultra low concentration deltamethrin loaded patch development and evaluation of its repellency against dengue vector Aedes (S) albopictus

BACKGROUND

Mosquito repellents and emanators confer protection against mosquito bites through spatial action of emanated vapours which are released into the adjoining environment. Synthetic insecticides released into the environment in ultra low volume vapour phase deter the mosquitoes from biting humans in a protected space.

METHODS

Formulation patches were prepared using the solvent evaporation method over a backing membrane and using Dibutylphthalate (DBT) as a plasticizer. The effect of formulation variables on the deltamethrin release from the patch matrices were studied under accelerated conditions, whereas, HPLC was used for quantitative estimation of deltamethrin. The prepared patch formulations were subjected to physicochemical studies, such as, deltamethrin content, thickness, weight variation, percent moisture content, moisture uptake, surface area and surface pH determination. Deltamethrin-polymer interaction and compatibility was ascertained using DSC and FT-IR, while surface morphology and deltamethrin distribution in the patch were studied using SEM technique. Repellent activity of the patch formulations was evaluated against Ae. albopictus mosquitoes.

RESULTS

Blends of polymeric combinations of polyvinylpyrrolidone (PVP) and ethyl-cellulose (EC) with admixture of deltamethrin provided prolonged repellent activity against Ae. albopictus mosquitoes. Physicochemical characterisation indicated the suitability of deltamethrin patch formulation with the polymeric combinations of PVP and EC. Patches were very effective against laboratory reared Ae. albopictus mosquitoes. No significant difference was observed between the performance of test patches and commercially available repellent cream Mosqshield®.

CONCLUSION

Deltamethrin loaded patches provided effective repellency against Ae. albopictus mosquitoes. The study emphasised that deltamethrin released to the environment in low concentration could be an excellent spatial repellent against hematophagous mosquitoes.

Immunomodulating effects and hypersensitivity reactions caused by Northeast Indian black fly salivary gland extract

The genus Simulium, black fly (Diptera), comprises >1800 species worldwide, of which 67 species under six subgenera have been well studied in India. While at the extreme, black fly bites can cause onchocerciasis or river blindness, the majority of clinical observations indicate mainly severe pain and continuous itching at bite sites. This investigation experimentally observed that black fly salivary extract (BFSE) causes unique biologic effects including immunomodulation, anti-coagulation, and hypersensitivity reactions in Wistar rats. Salivary glands from black flies were isolated, extracted in saline, and then ≈800 ng extract (BFSE) subcutaneously injected into rats. To evaluate potential immunosuppressive activity of the BFSE, serum levels of interleukins [IL]-6 and -10 and tumor necrosis factor [TNF]-α were assayed. To assess the BFSE impact on coagulation, activated partial thromboplastin time (aPTT), prothrombin time (PT), and bleeding time, as well as generation of coagulation activated factors I, IX, and X were analyzed. Anaphylaxis induction was monitored via electrocardiogram (ECG) and measures of blood pressure and rectal temperature. The data showed that BFSE treatment resulted in a significantly prolonged aPTT, PT, and bleeding time and reversibly inhibited generation of coagulation activated factors I, IX, and X. The extract also led to a prolonged (up to 48 h) suppression of serum IL-6, IL-10, and TNFα production. While these results suggest that BFSE possesses anti-thrombotic, anti-coagulant, and immunomodulatory activities, importantly, they also indicate that the extract has a capacity to induce anaphylaxis and acute cardiotoxicity.

Polymerase chain reaction detection of human host preference and Plasmodium parasite infections in field collected potential malaria vectors

This study was carried out to determine the human host preference and presence of Plasmodium parasite in field collected Anopheles mosquitoes among four villages around a military cantonment located in malaria endemic Sonitpur district of Assam, India. Encountered malaria vector mosquitoes were identified and tested for host preference and Plasmodium presence using PCR method. Human host preference was detected using simple PCR, whereas vectorial status for Plasmodium parasite was confirmed using first round PCR with genus specific primers and thereafter nested PCR with three Plasmodium species specific primers. Out of 1874 blood fed vector mosquitoes collected, 187 (10%) were processed for PCR, which revealed that 40·6% had fed on human blood; 9·2% of human blood fed mosquito were harbouring Plasmodium parasites, 71·4% of which were confirmed to Plasmodium falciparum. In addition to An. minimus, An. annularis and An. culicifacies were also found positive for malaria parasites. The present study exhibits the human feeding tendency of Anopheles vectors highlighting their malaria parasite transmission potential. The present study may serve as a model for understanding the human host preference of malaria vectors and detection of malaria parasite inside the anopheline vector mosquitoes in order to update their vectorial status for estimating the possible role of these mosquitoes in malaria transmission. The study has used PCR method and suggests that PCR-based method should be used in this entire malarious region to correctly report the vectorial position of different malaria vectors.

Prioritizing areas for malaria control using geographical information system in Sonitpur district, Assam, India

OBJECTIVE

To identify the malaria hot spots at health subcentre level in an endemic district using a geographical information system (GIS). The results will be useful for rapid retrieval of malaria information, and to prioritize malaria control efforts in identified hot spots.

STUDY DESIGN

Extraction, analysis and synthesis of relevant data.

METHODS

Malaria epidemiological data from 2006 to 2009 were analysed to determine the annual parasitic index, slide positivity rate, annual blood examination rate and Plasmodium falciparum percentage for each health subcentre in the district. Maps were produced using GIS, and integrated to identify the malaria hotspots.

RESULTS

Out of 288 health subcentres, GIS identified 10 hot spots at extremely high risk of malaria and 14 hot spots at high risk of malaria. Malaria may flare up in these hot spots whenever favourable transmission conditions arise. Health authorities have been advised to establish control measures in these selected hot spots for timely prevention.

CONCLUSION

There is a need for adequate monitoring and allocation of available resources for better interventions in the malaria hotspots. The GIS model used in this study can be used, even at village or cluster level, to pin point the malaria hot spots, and information can be updated and retrieved easily.

Influence of water physicochemical characteristics on Simuliidae (Diptera) prevalence in some streams of Meghalaya, India

BACKGROUND & OBJECTIVES

Simuliids (Diptera) are one of the medically important biting insects group and have worldwide distribution. Their immature stages proliferate in fast flowing river or stream water and have been considered as important ecological indicator.

METHODS

Aquatic stages of simuliids were collected and speciated from 16 different fresh water rivers and streams. Water flow rate was determined and water samples were analysed for various water variables such as water temperature, pH, dissolved oxygen concentration (DOC), dissolved oxygen saturation (DOS), conductivity, total dissolved solute (TDS), turbidity, resistivity and salinity. Linear regression was used to determine relationship between simuliid density and water variables, whereas multiple regression was used to determine the fitness for the presence of simuliid species. Principal component analysis (PCA) was used to determine the water parameters association with simuliid distribution.

RESULTS

Total 565 specimens comprising of three species namely, Simulium (S) barraudi Puri, S. (S) striatum Brunetti, and S. (S) himalayense Puri were recorded in the present study. Simulium barraudi was the most abundant (56.8%) and its density was high (χ2 = 289.3; df = 2; p <0.0001) as compared to the others. The average population size of each species was 188.3, whereas Simpson and Shannon-Wiener diversity indices were 0.4466 and 1.306 respectively. Linear regression showed that simuliid density was associated with the water flow rate. Principal component analysis indicated that the water parameters accounted for 42.25% variation along D1 axis, while 24.1% variation along D2 axis. Atleast two principal components have eigenvalue >1 and accounted for 32.6% of variation.

INTERPRETATION & CONCLUSION

Our study provides new information on simuliid species association with breeding water parameters in a little studied region of high biological interest. Turbidity, water flow and pH are important water parameters affecting the simuliid species prevalence. Each simuliid species preferred different sets of physicochemical parameters of breeding habitat, which are specific to that particular species. Therefore, simuliid species community as a whole cannot be considered as a suitable indicator of the streams water quality. In addition to describing simuliids, the information provided herein will be useful for the conservation of aquatic ecology and environment in Meghalaya state of India.

Vitex negundo inhibits cyclooxygenase-2 inflammatory cytokine-mediated inflammation on carrageenan-induced rat hind paw edema

Background:

Vitex negundo L. (Verbenaceae) is a hardy plant widely distributed in the Indian subcontinent and used for treatment of a wide spectrum of health disorders in traditional and folk medicine, some of which have been experimentally validated. In present study, we aimed to investigate the anti-inflammatory effects of V. negundo in carrageenan-induced paw edema in rats, and to investigate the probable mechanism of anti-inflammatory action.

Materials and Methods:

Paw edema was produced by injecting 1% solution of carrageenan, and the paw volume was measured before and after carrageenan injection up to 5 h. V. negundo leaf oil was extracted using a Clevenger apparatus and administered by a trans-dermal route to Wistar rats and the percentage of inhibition of inflammation was observed using a Plethysmometer by comparing a compound aerosol-based formulation with 1 mg diclofinac diethylamine BP and 7 mg methyl salicylate IP/kg body weight served as a standard drug whereas paraffin oil served as the placebo group. After withdrawing of blood, serum was separated and cyclooxygenase (COX)-1 and COX-2 inhibitory activities were measured by the enzyme immuno assay (EIA) method by using a COX inhibitor screening assay kit.

Results and Discussion:

V. negundo leaf oil significantly (P < 0.05) reduced the carrageenan-induced paw edema as compared to the placebo group (paraffin oil) and 1 mg diclofinac diethylamine BP and 7 mg methyl salicylate IP showed the maximum inhibition of paw edema as compared to the V. negundo leaf oil treated group and the control group. Also in the present study V. negundo leaf oil showed significantly (P < 0.05) inhibits COX-1 pathways rather than COX-2 pathways as compared to the V. negundo leaf oil treated group.

Conclusion:

It is suggested that the V. negundo leaf oil is a potent anti-inflammatory agent and acts via inhibition of COX-2 without much interfering COX-1 pathways.

Epidemiology and Risk Analysis of Malaria among Pregnant Women

Malaria remains a complex problem during the pregnancy, which threatens > 35 millions pregnant women every year. Malaria pathogenesis in pregnancy results in accumulation of infected RBCs in the intervillous spaces causing severe alterations leading to the reduced materno-foetal exchanges. In this article we have revisited the current evidences of clinical implications and overall burden of malaria in pregnancy. Many adverse aftermaths including, low birth weight, intrauterine growth retardation, preterm delivery, stillbirth and anemia were found associated with malaria in pregnant women. Despite of worldwide comprehensive control programmes for malaria in pregnancy, the disease control has been a daunting task everywhere. Socio cultural, economical, lack of awareness and various logistic problems compound the disease in developing countries. Thorough evidence based information and estimates, education and awareness and strengthening of prevention programmes are needed urgently to achieve success in malaria control in pregnancy.

Repellent activity of some essential oils against Simulium species in India

Use of repellents seems to be most reliable method of personal protection against annoyance and infections associated with haematophagous insects. We have investigated the biting activity of Simulium and tested the repellency of five essential oils extracted from Homalomena aromatica Schott (Alismatales: Araceae), Pogostemon heyneanus Bentham (Lamiales: Lamiaceae), Citrus aurantifolia Swingle (Sapindales: Rutaceae), Vitex negundo L. (Lamiales: Lamiaceae), and Ageratum conzoides L. (Asterales: Asteraceae) on the human volunteers against Simulium (blackflies) in three locations of Arunachal Pradesh, India. Blackflies preferred biting legs (> 79%) as compared to hand and face with profound biting activity during 1000-1100 h (> 23%) and 1500 - 1600 h (> 28%). The essential oil extracted from Homalomena aromatica, Vitex negundo and Ageratum conizoides provided > 2 h protection at 5% concentration and > 5 h protection at 10% concentration in all the three testing locations. The repellency of Homalomena aromatica, Vitex negundo and Ageratum conizoides essential oils after 6 h application was > 50% at 5% concentration and > 90% at 10% concentration. The study provides evidence for the potential of these essential oils in developing new repellents against blackflies.

A cross sectional investigation of malaria epidemiology among seven tea estates in Assam, India

In the present investigation, the epidemiology of malaria among seven tea estates of Nagaon and Udalguri districts of Assam, India has been described. A cross-sectional open study was carried out to understand the malaria epidemiology and associated risk factors among the tea tribes during March to September 2009. Out of 1,182 peripheral blood smears examined, 506 found positive for malaria (slide positivity rate, SPR = 42.8) with Plasmodium falciparum as predominant species. Dimakuchi tea estate was having highest SPR (P = 0.0275) and contributed more number of P. falciparum cases (P < 0.00001). Tea estates studied in both Udalguri and Nagaon districts were equally affected and the SPR recorded were 41.75 and 43.32% respectively. 154 malaria cases detected were having 'O' blood group but each blood group was found to have similar susceptibility of acquiring malaria infection (χ(2 ) = 3.603; P = 0.3076) and P. falciparum infection (χ(2 ) = 1.818; P = 0.6110). The SPR was highest among children more than 2 years of age group and variation in SPR among the age groups was statistically significant (χ(2 ) = 17.186; P = 0.0018). No gender biasing was observed in malaria distribution. Anemia was found associated with the infection among both the sexes. The findings suggest that tea estates are endemic for stable malaria transmission primarily due to P. falciparum and the prevalence rate decline with age, suggesting the development of protective immunity. Promising intervention measures could be able to reduce the malaria prevalence effectively in the study areas.

Malaria incidence among paramilitary personnel in an endemic area of Tripura

BACKGROUND & OBJECTIVES

Paramilitary operations along the Indo-Bangladesh border are adversely affected by malaria induced morbidity and mortality. Villages surrounding the paramilitary installations often serve as disease reservoirs. Malaria incidence in Tripura State Rifles (TSR) units in Dhalai District of Tripura was studied and the role of the village population in disease transmission was also assessed.

METHODS

Mass blood surveys were carried out among TSR personnel and villagers during 2007 to 2009. Malaria diagnosis through blood smear examination and rapid detection kits was done, and percentage parasitaemia was determined. Activity of malaria vectors was monitored using CDC light traps.

RESULTS

Slide positivity rates (SPR) in the neighbouring villages (51.4%) was significantly higher than that in TSR (27.7%) (P<0.0001). Malaria incidence in villages did not show seasonal variability while it was lowest during post-monsoon season in TSR (P<0.325; OR = 0.74). Per cent Pf parasitaemia was high in TSR (0.29) as compared to villagers (0.20) (P<0.0001). Anopheles minimus and An. dirus were the major malaria vectors observed.

INTERPRETATION & CONCLUSIONS

Paramilitary and public health authorities should adopt targeted measures to reduce the malaria incidence in the villages surrounding the paramilitary installations as the village populations play a major role in disease transmission.

Malaria epidemiology along Indo-Bangladesh border in Tripura State, India

Malaria epidemiological surveys were conducted in 16 villages along the Indo-Bangladesh border in Tripura, northeastern India. Insecticide resistance among malaria vectors and chloroquine resistance in the parasite were also studied along with monitoring of vector density using light traps. The epidemiological data indicated that malaria incidence was highest during June-July and lowest during November. Examination of blood smears collected through door to door surveys indicated slide positivity rate (SPR) of 25.2% and that Plasmodium falciparum was the predominant parasite (slide falciparum rate of 22.3%). The incidence rates of falciparum malaria varied significantly among the age groups (p<0.001) and 2-4 year olds were the most affected. Major malaria vectors recorded in light trap collections were An. dirus, An. minimus and An. philippinensis/nivipes. Chloroquine resistance studies indicated that treatment failure occurred in 35% of the cases and hence the use of artesunate combination therapy (ACT) was recommended for treatment of malaria in the area.