The Impact, Emerging Needs, and New Research Questions Arising from 12 Years of the Center for the Study of Complex Malaria in India

The Center for the Study of Complex Malaria in India (CSCMi) was launched in 2010 with the overall goal of addressing major gaps in our understanding of "complex malaria" in India through projects on the epidemiology, transmission, and pathogenesis of the disease. The Center was mandated to adopt an integrated approach to malaria research, including building capacity, developing infrastructure, and nurturing future malaria leaders while conducting relevant and impactful studies to assist India as it moves from control to elimination. Here, we will outline some of the interactions and impacts the Center has had with malaria policy and control counterparts in India, as well as describe emerging needs and new research questions that have become apparent over the past 12 years.

Learnings from two independent malaria elimination demonstration projects in India

PROBLEM

India and sub-Saharan Africa contributes about 85% of the global malaria burden, and India is committed to eliminating malaria by 2030.

APPROACH

Two novel initiatives-the Malaria Elimination Demonstration Project (MEDP) in Madhya Pradesh and Durgama Anchalare Malaria Nirakaran (DAMaN) in Odisha-were initiated independently to demonstrate that indigenous malaria can be eliminated in a short period of time.

LOCAL SETTING

These initiatives focused on rural, tribal areas where there is a high malaria burden and complex epidemiology.

RELEVANT CHANGES

The case management and vector control strategies used in these programmes were based on the national guidelines, with context-specific changes and introduction of accountability at management, operational, technical and financial levels. The MEDP achieved a 91% reduction in malaria cases and recorded zero transmission for 6 consecutive and a total of 9 mo. The DAMaN project brought about an 88% reduction in malaria cases.

LESSONS LEARNED

Malaria elimination will require robust surveillance and case management, monitoring of vector control interventions, community-centric information education communication and behaviour change communication initiatives and management controls, as well as regular internal and external reviews.

A model for malaria elimination based on learnings from the Malaria Elimination Demonstration Project, Mandla district, Madhya Pradesh

Background

Malaria Elimination Demonstration Project (MEDP) was started as a Public-Private-Partnership between the Indian Council of Medical Research through National Institute of Research in Tribal Health, Govt. of Madhya Pradesh and Foundation of Disease Elimination and Control of India, which is a Corporate Social Responsibility (CSR) initiative of the Sun Pharmaceutical Industries Limited. The project’s goal was to demonstrate that malaria can be eliminated from a high malaria endemic district along with prevention of re-establishment of malaria and to develop a model for malaria elimination using the lessons learned and knowledge acquired from the demonstration project.

Methods

The project employed tested protocols of robust surveillance, case management, vector control, and capacity building through continuous evaluation and training.  The model was developed using the learnings from the operational plan, surveillance and case management, monitoring and feedback, entomological investigations and vector control, IEC and capacity building, supply chain management, mobile application (SOCH), and independent reviews of MEDP.

Results

The MEDP has been operational since April 2017 with field operations from August 2017, and has observed: (1) reduction in indigenous cases of malaria by about 91 %; (2) need for training and capacity building of field staff for diagnosis and treatment of malaria; (3) need for improvement insecticide spraying and for distribution and usage of bed-nets; (4) need for robust surveillance system that captures and documents information on febrile cases, RDT positive individuals, and treatments provided; (5) need for effective supervision of field staff based on advance tour plan; (6) accountability and controls from the highest level to field workers; and (7) need for context-specific IEC.

Conclusions

Malaria elimination is a high-priority public health goal of the Indian Government with a committed deadline of 2030. In order to achieve this goal, built-in systems of accountability, ownership, effective management, operational, technical, and financial controls will be crucial components for malaria elimination in India. This manuscript presents a model for malaria elimination with district as an operational unit, which may be considered for malaria elimination in India and other countries with similar geography, topography, climate, endemicity, health infrastructure, and socio-economic characteristics.

Subnational mapping of under-5 and neonatal mortality trends in India: the Global Burden of Disease Study 2000-17

BACKGROUND

India has made substantial progress in improving child survival over the past few decades, but a comprehensive understanding of child mortality trends at disaggregated geographical levels is not available. We present a detailed analysis of subnational trends of child mortality to inform efforts aimed at meeting the India National Health Policy (NHP) and Sustainable Development Goal (SDG) targets for child mortality.

METHODS

We assessed the under-5 mortality rate (U5MR) and neonatal mortality rate (NMR) from 2000 to 2017 in 5 × 5 km grids across India, and for the districts and states of India, using all accessible data from various sources including surveys with subnational geographical information. The 31 states and groups of union territories were categorised into three groups using their Socio-demographic Index (SDI) level, calculated as part of the Global Burden of Diseases, Injuries, and Risk Factors Study on the basis of per-capita income, mean education, and total fertility rate in women younger than 25 years. Inequality between districts within the states was assessed using the coefficient of variation. We projected U5MR and NMR for the states and districts up to 2025 and 2030 on the basis of the trends from 2000 to 2017 and compared these projections with the NHP 2025 and SDG 2030 targets for U5MR (23 deaths and 25 deaths per 1000 livebirths, respectively) and NMR (16 deaths and 12 deaths per 1000 livebirths, respectively). We assessed the causes of child death and the contribution of risk factors to child deaths at the state level.

FINDINGS

U5MR in India decreased from 83·1 (95% uncertainty interval [UI] 76·7-90·1) in 2000 to 42·4 (36·5-50·0) per 1000 livebirths in 2017, and NMR from 38·0 (34·2-41·6) to 23·5 (20·1-27·8) per 1000 livebirths. U5MR varied 5·7 times between the states of India and 10·5 times between the 723 districts of India in 2017, whereas NMR varied 4·5 times and 8·0 times, respectively. In the low SDI states, 275 (88%) districts had a U5MR of 40 or more per 1000 livebirths and 291 (93%) districts had an NMR of 20 or more per 1000 livebirths in 2017. The annual rate of change from 2010 to 2017 varied among the districts from a 9·02% (95% UI 6·30-11·63) reduction to no significant change for U5MR and from an 8·05% (95% UI 5·34-10·74) reduction to no significant change for NMR. Inequality between districts within the states increased from 2000 to 2017 in 23 of the 31 states for U5MR and in 24 states for NMR, with the largest increases in Odisha and Assam among the low SDI states. If the trends observed up to 2017 were to continue, India would meet the SDG 2030 U5MR target but not the SDG 2030 NMR target or either of the NHP 2025 targets. To reach the SDG 2030 targets individually, 246 (34%) districts for U5MR and 430 (59%) districts for NMR would need a higher rate of improvement than they had up to 2017. For all major causes of under-5 death in India, the death rate decreased between 2000 and 2017, with the highest decline for infectious diseases, intermediate decline for neonatal disorders, and the smallest decline for congenital birth defects, although the magnitude of decline varied widely between the states. Child and maternal malnutrition was the predominant risk factor, to which 68·2% (65·8-70·7) of under-5 deaths and 83·0% (80·6-85·0) of neonatal deaths in India could be attributed in 2017; 10·8% (9·1-12·4) of under-5 deaths could be attributed to unsafe water and sanitation and 8·8% (7·0-10·3) to air pollution.

INTERPRETATION

India has made gains in child survival, but there are substantial variations between the states in the magnitude and rate of decline in mortality, and even higher variations between the districts of India. Inequality between districts within states has increased for the majority of the states. The district-level trends presented here can provide crucial guidance for targeted efforts needed in India to reduce child mortality to meet the Indian and global child survival targets. District-level mortality trends along with state-level trends in causes of under-5 and neonatal death and the risk factors in this Article provide a comprehensive reference for further planning of child mortality reduction in India.

FUNDING

Bill & Melinda Gates Foundation; and Indian Council of Medical Research, Department of Health Research, Ministry of Health and Family Welfare, Government of India.

Effect of Helical Winding Angle on External Pressure based Buckling of Partially Filled Thin Composite Cylindrical Shells

Effect of helical winding angle on buckling load of thin composite tubes is investigated in this work.  Experiments are conducted on both empty and partially filled S2 glass tubes to estimate contribution of strength to the tubes by the filler material.  Chosen filler material mechanically simulates behavior of typical solid propellant used in aerospace application.   FE analysis with non-linear effect correlates well with the experimental data.  Three series of experiments are conducted to quantify effect of helical winding angle and increase in volumetric loading fraction(VLF).  Results confirm appreciable improvement in strength of filled tubes for higher VLF.  For the chosen pattern of winding, lower winding angle provides more strength to the tubes against external pressure buckling.   

Recent advances on T-cell exhaustion in malaria infection

T-cell exhaustion reportedly leads to dysfunctional immune responses of antigen-specific T cells. Investigations have revealed that T cells expand into functionally defective phenotypes with poor recall/memory abilities to parasitic antigens. The exploitation of co-inhibitory pathways represent a highly viable area of translational research that has very well been utilized against certain cancerous conditions. Malaria, at times, evolve into a sustained chronic state where T cells express several co-inhibitory molecules (negative immune checkpoints) facilitating parasite escape and sub-optimal protective responses. Experimental evidence suggests that blockade of co-inhibitory molecules on T cells in malaria could result in the sustenance of protective responses together with dramatic parasite clearance. The role of several co-inhibitory molecules in malaria infection largely remain unclear, and here we discussed the potential applicability of co-inhibitory molecules in the management of malaria with a view to harness protective host responses against chronic disease and associated consequences.

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

BACKGROUND & OBJECTIVES

Aedes mosquito control has gained much importance nowadays in view of rise in number of reported cases of dengue and chikungunya in India and other countries. In the present study, C21 attracticide (containing a pheromone and an insect growth regulator—IGR, developed by Defence Research and Development Establishment (DRDE), Gwalior, India was tested for its feasibility for surveillance and control of Aedes mosquito in a multicentric mode from October 2007 to June 2012 in urban (Delhi, and Bengaluru district, Karnataka) and suburban (Alappuzha district, Kerala) settings of the country in three phases.

METHODS

Across the randomly selected households in each study area, two to four containers treated with attracticide (experimental) and untreated (control) were placed and monitored by trained surveillance workers on weekly/ fortnightly basis for determining the presence of eggs, larvae and pupae. Container positivity, percent larvae, egg and pupae collected were determined during different phases and analyzed statistically using SPSS 18.0.

RESULTS

Container positivity was found statistically significant at Bengaluru and Alappuzha, Kerala while in Delhi, it was found non-significant. Eggs collected from experimental containers were significantly higher in comparison to control at all the locations except Delhi. Also larvae collected from control containers were significantly higher at all the locations except Bengaluru. Pupae collected from control containers remained significantly higher at all the locations as no pupal formation was recorded from experimental containers.

INTERPRETATION & CONCLUSION

The use of C21 attracticide hampered pupal formation, thus inhibiting adult population in the study areas. The study established that C21 attracticide was efficacious in the field conditions and has potential for use in surveillance and management of dengue and chikungunya mosquitoes.

A note on the insecticide susceptibility status of principal malaria vector Anopheles culicifacies in four states of India

BACKGROUND & OBJECTIVES

The major malaria vector, Anopheles culicifacies Giles is reported to contribute ~ 65% of the malaria cases in India. This species developed resistance to DDT and later to HCH, malathion and also to pyrethroids in some states due to their use in the national malaria control programme. In the present study, insecticide susceptibility of this species was monitored in four states of India.

METHODS

To determine insecticide susceptibility status of the major malaria vector An. culicifacies, adult mosquitoes were collected from different localities of 32 tribal districts in the states of Andhra Pradesh, Odisha, Jharkhand and West Bengal during October/November 2009-10. Mosquitoes were collected from stratified ecotypes comprising a group of districts in West Bengal and individual districts in three other states. Mosquitoes were exposed to papers treated with WHO diagnostic dose: 4% DDT, 5% malathion and 0.05% deltamethrin following the WHO tube method.

RESULTS

RESULTS provided the susceptibility status of An. culicifacies to different insecticides used in the public health programme in 32 districts in four states. An. culicifacies was found resistant to DDT (mortality range 0-36%) in all the 32 districts; to malathion it was resistant in 14 districts, verification required in 10 districts and susceptible in eight districts (mortality range 32.2-100%). It was resistant to deltamethrin in four districts, verification required in 11 districts and susceptible in 17 districts (mortality range 43.3-100%).

INTERPRETATION & CONCLUSION

Development of widespread resistance to insecticides used in public health sprays for vector control including to pyrethroids in An. culicifacies in the surveyed districts is of great concern for the malaria control programme as the major interventions for vector control are heavily reliant on chemical insecticides, mainly synthetic pyrethroids used both for indoor residual spraying and for long-lasting insecticidal nets. Thus, there is a need to periodically monitor and update the susceptibility status of malaria vector(s) to suggest alternative vector control strategies for effective disease management.

Safety, efficacy and population pharmacokinetics of fixed-dose combination of artesunate-mefloquine in the treatment of acute uncomplicated Plasmodium falciparum malaria in India

BACKGROUND & OBJECTIVES

India has switched over to artemisinin-based combination therapy (ACT) for the treatment of acute uncomplicated Plasmodium falciparum malaria and the ACT used in the national programme is artesunate + sulphadoxine-pyrimethamine. Since the efficacy of ACT is dependent also on the partner drug, there is a need to evaluate and deploy multiple ACTs.

METHODS

This multicentre, single-arm, open-label clinical trial was carried out to assess the efficacy, safety and population pharmacokinetics of a fixed dose combination (FDC) artesunate mefloquine (ASMQ) in P. falciparum infected, Indian adults at Panjim, Goa, and Mangalore, Karnataka between December 2007 and November 2008.

RESULTS

A total of 77 patients (males 74) were screened and enrolled: 42 at Goa and 35 at Mangalore with a median age of 25 yr (range 18-55 yr). One patient failed in treatment on D53, a PCR proven new infection, seven developed recurrent vivax parasitaemia and 11 did not have a parasitological endpoint. By per protocol analysis, the D63 cure rate was 58/59 (98.3; 95% C.I. 90.9-99.9%), and 58/58, with PCR correction. ASMQ was well-tolerated and no serious adverse events were reported.

INTERPRETATION & CONCLUSION

The study showed that the ASMQ FDC was efficacious and well-tolerated for the treatment of acute, uncomplicated P. falciparum malaria in highly endemic, chloroquine resistant areas of Goa and Mangalore. It is a viable option for India.

Detection of in-vivo chloroquine resistance inPlasmodium falciparumfrom Rameswaram Island, a pilgrim centre in southern India

Resistance to chloroquine (CQ) in Plasmodium falciparum is one of the main causes of the wide-spread resurgence of malaria in India and a challenge to the effective control of the disease. In the pilgrim centre of Rameswaram Island, malaria has persisted despite the various control measures undertaken over the years. When CQ resistance in Rameswaram was investigated in vivo, recrudescent parasitaemias were observed in 25 (58%) of the 43 study subjects who were given CQ and completed follow-up, all occurring between days 10 and 28 (late treatment failures). The results of the msp(1), msp(2) and glurp genotyping of paired samples of P. falciparum, collected on day 0 and the day of recrudescence from 23 of the apparent treatment failures, indicated that 21 (91%) of the 23 were probably true treatment failures. All of the paired samples harboured parasites with the K76T mutation in their pfcrt genes, and subsequent sequencing of nine day-0 samples revealed the SVMNT haplotype in all nine. This is the first report of in-vivo drug resistance in P. falciparum from Rameswaram Island. Such resistance, which is probably the result of the indiscriminate use of CQ and/or the import of malaria from mainland India, warrants a change in the drug regimen used locally for the first-line treatment of uncomplicated, P. falciparum malaria, to make treatment more effective and slow the development and spread of more foci of CQ resistance.

Emerging and re-emerging arboviral diseases in Southeast Asia

Arthropod-borne viruses (arboviruses) have become significant public health problems, with the emergence and re-emergence of arboviral diseases nearly worldwide. The most populated Southeast Asia region is particularly vulnerable. The arboviral diseases such as dengue (DEN), Japanese encephalitis (JE), West Nile virus (WNV), chikungunya fever (CHIK), hemorrhagic fevers such as Crimean-Congo hemorrhagic (CCHF) fever, Kyasanur forest disease virus (KFDV), etc. are on the rise and have spread unprecedentedly, causing considerable burden of disease. The emergence/re-emergence of these diseases is associated with complex factors, such as viral recombination and mutation, leading to more virulent and adaptive strains, urbanization and human activities creating more permissive environment for vector-host interaction, and increased air travel and commerce. Climate is a major factor in determining the geographic and temporal distribution of arthropods, the characteristics of arthropod life cycles, the consequent dispersal patterns of associated arboviruses, the evolution of arboviruses; and the efficiency with which they are transmitted from arthropods to vertebrate hosts. The present and future arboviral threats must be mitigated by priority actions such as improving surveillance and outbreak response, establishing collaboration and communication intersectorally, and strengthening the prevention and control programmes along with improving biosafety aspects with regards to highly infectious nature of these arboviral diseases. Evidence from research needs to be generated and priority areas for research defined.

Changing epidemiology of dengue in South-East Asia

The burden of dengue and its potential threat to global health are now globally recognized, with 2.5 billion people at risk worldwide. The pathogenesis of severe dengue is particularly intriguing with the involvement of different immune factors. Also, the epidemiology of dengue in South-East Asia is undergoing a change in the human host, the dengue virus and the vector bionomics. Shift in affected age groups, sex differences and expansion to rural areas are evident, while the virulence and genotype of the virus determine the severity and time interval between sequential infections. The Aedes mosquito, a potent and adaptive vector, has evolved in longevity and survival, affected by seasonality and climate variability, socio-cultural and economic factors of human habitation and development. This review provides insights into the changing epidemiology and its factors in South-East Asia, one of the most important epicentres of dengue in the world, highlighting the major factors influencing these rapid changes. Addressing the changes may help mitigate the challenges in the current dengue control and prevention efforts.

Population cytogenetic and molecular evidence for existence of a new species in Anopheles fluviatilis complex (Diptera: Culicidae)

Anopheles fluviatilis James, an important malaria vector in the Oriental region has been established as a complex of at least three cryptic species which vary in their biological characteristics and malaria transmission potential. The sibling species S, T and U of Fluviatilis Complex can be identified by examination of species-specific fixed inversions in the polytene chromosomes and can also be differentiated by an allele-specific PCR assay based on differences in the D3 region of 28S ribosomal DNA (rDNA) of these species. Here we report a new An. fluviatilis population from villages under Laksar Community Health Centre, District Haridwar (Uttarakhand state), India which differs from the three sibling species of Fluviatilis Complex by two fixed paracentric inversions, s(1) and S in polytene chromosome arms 2 and 3 respectively. Longitudinal study carried out in study villages showed that the new cytotype was sympatric with species T and U in all the collections and no inversion heterozygotes were observed between them. Thus presence of two fixed paracentric inversions in polytene chromosomes with total absence of inversion heterozygotes demonstrates reproductive isolation which unequivocally establishes this cytological variant as a new species, provisionally designated as species V in the Fluviatilis Complex. Analysis of DNA sequences of D3 domain of 28S rDNA and ITS 2 region has also shown that species V is distinctly different from species S, T and U. With the discovery of new species in the Fluviatilis Complex, in-depth studies are required to know its distribution pattern and biological characteristics and to ascertain its role in malaria transmission.

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

BACKGROUND & OBJECTIVES

In the present study, Icon®Life net, a long-lasting polyethylene net, 100 denier and bursting strength of minimum 280 kpa incorporated with deltamethrin @ 65 mg/m2 was evaluated for its efficacy in reducing the density of malaria vector Anopheles culicifacies and impact on malaria prevalence in a malaria endemic area of District Gautam Budh Nagar, India.

METHODS

Wash resistance of Icon®Life LLIN was determined up to 20 serial washings using An. culicifacies in cone bioassays under field conditions. Efficacy of Icon®Life LLIN was determined in the field in three sets of villages in District Gautam Budh Nagar (Uttar Pradesh), India, selected randomly for the intervention with Icon®Life LLIN, untreated nets and a control without any intervention for the period of August 2008-July 2009. Entomological and malariometric indices in all the three villages were compared during pre- and post-intervention periods for one year against An. culicifacies. A survey was also conducted in the village provided with Icon®Life LLIN to assessing the perception of community regarding acceptance of these nets by the community.

RESULTS

In cone bioassays on Icon®Life LLIN with An. culicifacies, >95% knockdown within 1 h and 100% mortality after 24 h exposure were reported even after 20× serial washings under field conditions. Results of the field study revealed reduced entry rate, resting density and parity rate of An. culicifacies in the village with Icon®Life LLIN when compared to no net and untreated net villages. Number of malaria cases reported were less in the Icon®Life LLIN used villages when compared to other two villages. The community compliance and acceptance was high and no adverse health events were reported by the households using these nets.

CONCLUSIONS

Icon®Life LLIN is an effective intervention for the control of An. culicifacies transmitted malaria in India. Long-term studies are indicated for the duration of effectiveness and to ascertain the epidemiological impact of the use of Icon®Life nets.

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

BACKGROUND & OBJECTIVES

In the present study, an attempt was made to find reasons of ineffectiveness of indoor residual spray to interrupt malaria transmission by investigating the behaviour of two variants of Anopheles stepnesi, viz. type form and mysorensis in rural areas of Rajasthan, India.

METHODS

Both low malarious (DDT spray from 1958 to 1976) and high malarious (DDT spray from 1958 to April 2006) villages were selected for the study in Arid zone district Jodhpur, Rajasthan during March-April 2006. Resting behaviour of the species during all its movement rhythms covering 24 h period related to: (i) swarming/ mating; (ii) pre- and post-biting rest; (iii) after feed resting between hoping movements; (iv) night and day time resting and; (v) diel activity movements in response to temperature changes, were carried out.

RESULTS

The results showed that household objects like cupboards, furnitures, hanging clothes, goods stacked on loft, stored clothes, cobwebs and floor were the dominant resting sites both in sprayed and unsprayed villages. About 95 and 97% of An. stephensi preferred to rest on household objects of unsprayed and sprayed villages respectively. There was no significant difference in resting behaviour of the species in both groups of villages (p >0.05). The pre-biting resting time was recorded as 5 to 15 min whereas post-biting resting time lasted for 15 to 25 min. After biting outdoor (in courtyard--open to sky) species starts entering the rooms at around 2330 hrs. It was observed that during III quarter (0100 to 0400 hrs) maximum species entered into the room were 56% in unsprayed and 62% in sprayed villages. Statistically there was no significant difference in the entry of mosquitoes (p >0.05) in both the groups of villages.

CONCLUSION

Before DDT era, An. stephensi was found resting at all heights of the walls inside the human dwellings. Present study revealed that An. stephensi is trying to avoid sprayable surfaces and tend to rest on unsprayable surfaces during all its movement rhythms starting from swarming, pre-/post-biting and during hopping movements in the courtyard and thereafter household objects inside the room as final day time resting. It was concluded that changed behaviour of resting of An. stephensi on unsprayable objects in sprayed rooms largely accounted for failure of malaria control. Control of An. stephensi, thus requires an integrated vector control strategy based upon interesectoral, environmental, larviciding with chemical/biolarvicide and use of larvivorous fish wherever feasible. Such a control strategy offers cost-effective and sustainable option than indoor residual spray.

The malaria parasite Plasmodium vivax exhibits greater genetic diversity than Plasmodium falciparum

We sequenced and annotated the genomes of four P. vivax strains collected from disparate geographic locations, tripling the number of genome sequences available for this understudied parasite and providing the first genome-wide perspective of global variability in this species. We observe approximately twice as much SNP diversity among these isolates as we do among a comparable collection of isolates of P. falciparum, a malaria-causing parasite that results in higher mortality. This indicates a distinct history of global colonization and/or a more stable demographic history for P. vivax relative to P. falciparum, which is thought to have undergone a recent population bottleneck. The SNP diversity, as well as additional microsatellite and gene family variability, suggests a capacity for greater functional variation in the global population of P. vivax. These findings warrant a deeper survey of variation in P. vivax to equip disease interventions targeting the distinctive biology of this neglected but major pathogen.

Vector control interventions for visceral leishmaniasis elimination initiative in South Asia, 2005-2010

The Visceral Leishmaniasis (VL) Elimination Initiative in the Indian subcontinent was launched in 2005 as a joint effort between the governments in the Region (India, Nepal and Bangladesh) and the World Health Organization (WHO). The objective is to reduce the annual VL incidence below 1/10,000 inhabitants by 2015 based on detection and treatment of VL cases and vector control. We present here a review of studies published in the period 2005-2010 on the efficacy of different tools to control Phlebotomus argentipes. The review indicates that the current indoor residual spraying (IRS) and novel vector control methods mainly insecticide treated nets (ITN) have low effectiveness for several reasons. Efforts to improve quality of IRS operations and further research on alternative and integrated vector control methods need to be promoted to reach the VL elimination target by 2015.

Mosquito biting activity on humans & detection of Plasmodium falciparum infection in Anopheles stephensi in Goa, India

Background & objectives:

Knowledge of the bionomics of mosquitoes, especially of disease vectors, is essential to plan appropriate vector avoidance and control strategies. Information on biting activity of vectors during the night hours in different seasons is important for choosing personal protection measures. This study was carried out to find out the composition of mosquito fauna biting on humans and seasonal biting trends in Goa, India.

Methods:

Biting activities of all mosquitoes including vectors were studied from 1800 to 0600 h during 85 nights using human volunteers in 14 different localities of three distinct ecotypes in Goa. Seasonal biting trends of vector species were analysed and compared. Seasonal biting periodicity during different phases of night was also studied using William's mean.

Results:

A total of 4,191 mosquitoes of five genera and 23 species were collected. Ten species belonged to Anopheles, eight to Culex, three to Aedes and one each to Mansonia and Armigeres. Eleven vector species had human hosts, including malaria vectors Anopheles stephensi (1.3%), An. fluviatilis (1.8%), and An. culicifacies (0.76%); filariasis vectors Culex quinquefasciatus (40.8%) and Mansonia uniformis (1.8%); Japanese encephalitis vectors Cx. tritaeniorhynchus (17.4%), Cx. vishnui (7.7%), Cx. pseudovishnui (0.1%), and Cx. gelidus (2.4%); and dengue and chikungunya vectors Aedes albopictus (0.9%) and Ae. aegypti (0.6%). Two An. stephensi of the total 831 female anophelines, were found positive for P. falciparum sporozoites. The entomological inoculation rate (EIR) of P. falciparum was 18.1 and 2.35 for Panaji city and Goa, respectively.

Interpretation & conclusions:

Most of the mosquito vector species were collected in all seasons and throughout the scotophase. Biting rates of different vector species differed during different phases of night and seasons. Personal protection methods could be used to stop vector-host contact.

Effectiveness and durability of Interceptor® long-lasting insecticidal nets in a malaria endemic area of central India

BACKGROUND

In the present study, Interceptor®, long-lasting polyester net, 75 denier and bursting strength of minimum 250 kPa coated with alpha-cypermethrin @ 200 mg/m² was evaluated for its efficacy in reducing the mosquito density, blood feeding inhibition and malaria incidence in a tribal dominated malaria endemic area in Chhattisgarh state, central India. Its durability, washing practices and usage pattern by the community was also assessed up to a period of three years.

METHODS

The study was carried out in two phases. In the first phase (September 2006 to August 2007), 16 malaria endemic villages in district Kanker were randomized into three groups, viz. Interceptor net (LN), untreated polyester net (100 denier) and without net. Malaria cases were detected by undertaking fortnightly surveillance by home visits and treated as per the national drug policy. Mosquito collections were made by hand catch and pyrethrum space spray methods from human dwellings once every month. Slide positivity rate (SPR) and malaria incidence per 1000 population (PI) were compared between the three study arms to assess the impact of use of Interceptor nets. Simultaneously, wash resistance studies were carried out in the laboratory by doing cone bioassays on Interceptor LNs washed up to 20 times. Activities undertaken in second Phase (April 2008 to October 2009) after an interval of about 18 months post-net distribution included questionnaire based surveys at every six months, i.e. 18, 24, 30 and 36 months to observe durability, usage pattern of LNs and washing practices by the community. After 36 months of field use, 30 nets were retrieved and sampled destructively for chemical analysis.

RESULTS

Interceptor nets were found effective in reducing the density, parity rate and blood feeding success rate of main malaria vector Anopheles culicifacies as compared to that in untreated net and no net villages. SPR in LN villages was 3.7% as compared to 6.5% in untreated and 11% in no net villages. PI in LN villages was 16.4 in comparison to 24.8 and 44.2 in untreated polyester net and no net villages respectively. In surveys carried out after three years of initial distribution, 78.7% (737/936) nets were still in possession with the households, of which 68% were used every night. An. culicifacies mortality was >80% in cone bioassays done on LNs washed up to 20 times in laboratory. Mean alpha-cypermethrin content was 43.5 ± 31.7 mg/m² on Interceptor LNs withdrawn after three years of household use against the baseline specification of 200 mg/m². A gradual increase in the proportion of holed nets was observed with the increased period of usage.

CONCLUSION

Interceptor nets were highly effective in reducing vector densities as well as malaria incidence in the study villages. Availability of 78% nets with the households in usable condition clearly indicated durability of Interceptor LNs up to three years in the rural setting of India. The nets were found to contain an effective concentration of alpha-cypermethrin against malaria vector after three years of household use.

Artesunate-amodiaquine fixed dose combination for the treatment of Plasmodium falciparum malaria in India

Background

Artemisinin-based combination therapy (ACT) has been recommended for the treatment of falciparum malaria by the World Health Organization. Though India has already switched to ACT for treating falciparum malaria, there is need to have multiple options of alternative forms of ACT. A randomized trial was conducted to assess the safety and efficacy of the fixed dose combination of artesunate-amodiaquine (ASAQ) and amodiaquine (AQ) for the treatment of uncomplicated falciparum malaria for the first time in India. The study sites are located in malaria-endemic, chloroquine-resistant areas.

Methods

This was an open label, randomized trial conducted at two sites in India from January 2007 to January 2008. Patients between six months and 60 years of age having Plasmodium falciparum mono-infection were randomly allocated to ASAQ and AQ arms. The primary endpoint was 28-day PCR-corrected parasitological cure rate.

Results

Three hundred patients were enrolled at two participating centres, Ranchi, Jharkhand and Rourkela, Odisha. Two patients in AQ arm had early treatment failure while there was no early treatment failure in ASAQ arm. Late treatment failures were seen in 13 and 12 patients in ASAQ and AQ arms, respectively. The PCR-corrected cure rates in intent-to-treat population were 97.51% (94.6-99.1%) in ASAQ and 88.65% (81.3-93.9%) in AQ arms. In per-protocol population, they were 97.47% (94.2-99.2%) and 88.30% (80-94%) in ASAQ and AQ arms respectively. Seven serious adverse events (SAEs) were reported in five patients, of which two were reported as related to the treatment. All SAEs resolved without sequel.

Conclusion

The fixed dose combination of ASAQ was found to be efficacious and safe treatment for P. falciparum malaria. Amodiaquine also showed acceptable efficacy, making it a suitable partner of artesunate. The combination could prove to be a viable option in case India opts for fixed dose combination ACT.

Clinical trial registry

ISRCTN84408319

Mutant pfcrt "SVMNT" haplotype and wild type pfmdr1 "N86" are endemic in Plasmodium vivax dominated areas of India under high chloroquine exposure

Background

Chloroquine resistance (CQR) phenotype in Plasmodium falciparum is associated with mutations in pfcrt and pfmdr-1 genes. Mutations at amino acid position 72-76 of pfcrt gene, here defined as pfcrt haplotype are associated with the geographic origin of chloroquine resistant parasite. Here, mutations at 72-76 and codon 220 of pfcrt gene and N86Y pfmdr-1 mutation were studied in blood samples collected across 11 field sites, inclusive of high and low P. falciparum prevalent areas in India. Any probable correlation between these mutations and clinical outcome of CQ treatment was also investigated.

Methods

Finger pricked blood spotted on Whatman No.3 papers were collected from falciparum malaria patients of high and low P. falciparum prevalent areas. For pfcrt haplotype investigation, the parasite DNA was extracted from blood samples and used for PCR amplification, followed by partial sequencing of the pfcrt gene. For pfmdr-1 N86Y mutation, the PCR product was subjected to restriction digestion with AflIII endonuclease enzyme.

Results

In 240 P. falciparum isolates with reported in vivo CQ therapeutic efficacy, the analysis of mutations in pfcrt gene shows that mutant SVMNT-S (67.50%) and CVIET-S (23.75%) occurred irrespective of clinical outcome and wild type CVMNK-A (7.91%) occurred only in adequate clinical and parasitological response samples. Of 287 P. falciparum isolates, SVMNTS 192 (66.89%) prevailed in all study sites and showed almost monomorphic existence (98.42% isolates) in low P. falciparum prevalent areas. However, CVIETS-S (19.51%) and CVMNK-A (11.84%) occurrence was limited to high P. falciparum prevalent areas. Investigation of pfmdr-1 N86Y mutation shows no correlation with clinical outcomes. The wild type N86 was prevalent in all the low P. falciparum prevalent areas (94.48%). However, mutant N86Y was comparably higher in numbers at the high P. falciparum prevalent areas (42.76%).

Conclusions

The wild type pfcrt gene is linked to chloroquine sensitivity; however, presence of mutation cannot explain the therapeutic efficacy of CQ in the current scenario of chloroquine resistance. The monomorphic existence of mutant SVMNT haplotype, infer inbreeding and faster spread of CQR parasite in areas with higher P. vivax prevalance and chloroquine exposure, whereas, diversity is maintained in pfcrt gene at high P. falciparum prevalent areas.

Plasmodium vivax lineages: geographical distribution, tandem repeat polymorphism, and phylogenetic relationship

Background

Multi-drug resistance and severe/complicated cases are the emerging phenotypes of vivax malaria, which may deteriorate current anti-malarial control measures. The emergence of these phenotypes could be associated with either of the two Plasmodium vivax lineages. The two lineages had been categorized as Old World and New World, based on geographical sub-division and genetic and phenotypical markers. This study revisited the lineage hypothesis of P. vivax by typing the distribution of lineages among global isolates and evaluated their genetic relatedness using a panel of new mini-satellite markers.

Methods

18S SSU rRNA S-type gene was amplified from 420 Plasmodium vivax field isolates collected from different geographical regions of India, Thailand and Colombia as well as four strains each of P. vivax originating from Nicaragua, Panama, Thailand (Pak Chang), and Vietnam (ONG). A mini-satellite marker panel was then developed to understand the population genetic parameters and tested on a sample subset of both lineages.

Results

18S SSU rRNA S-type gene typing revealed the distribution of both lineages (Old World and New World) in all geographical regions. However, distribution of Plasmodium vivax lineages was highly variable in every geographical region. The lack of geographical sub-division between lineages suggests that both lineages are globally distributed. Ten mini-satellites were scanned from the P. vivax genome sequence; these tandem repeats were located in eight of the chromosomes. Mini-satellites revealed substantial allelic diversity (7-21, AE = 14.6 ± 2.0) and heterozygosity (He = 0.697-0.924, AE = 0.857 ± 0.033) per locus. Mini-satellite comparison between the two lineages revealed high but similar pattern of genetic diversity, allele frequency, and high degree of allele sharing. A Neighbour-Joining phylogenetic tree derived from genetic distance data obtained from ten mini-satellites also placed both lineages together in every cluster.

Conclusions

The global lineage distribution, lack of genetic distance, similar pattern of genetic diversity, and allele sharing strongly suggested that both lineages are a single species and thus new emerging phenotypes associated with vivax malaria could not be clearly classified as belonging to a particular lineage on basis of their geographical origin.

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

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

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

BACKGROUND & OBJECTIVES

Prevention of malaria is a major technical and operational problem in displaced and mobile populations such as refugee camps and temporary labour settlements. Insecticide incorporated plastic sheeting is a new technology to control mosquitoes in emergency shelters and also temporary habitations at different locations. In view of this, efficacy of ZeroFly® , an insecticide incorporated plastic sheeting (factory treated with deltamethrin 2.0 g/kg or 265 mg/m2 ) was evaluated for its efficacy against malaria vectors and its impact on malaria incidence in temporary labour settlements in two urban areas in India.

METHODS

This trial was conducted in two labour settlements in two urban areas, Delhi and Noida (U.P.), India with ~ 250 populations. In an area, two localities were selected for intervention with ZeroFly and untreated plastic sheets (control). Entomological and epidemiological data were collected using standard methods for one year.

RESULTS

Baseline studies on the susceptibility of mosquitoes in Delhi and Noida areas revealed 100% susceptibility of the malaria vector species Anopheles culicifacies and An. stephensi to deltamethrin. Cone bioassay tests performed against An. culicifacies and An. stephensi to determine the efficacy of ZeroFly sheets showed 100% mortality against An. culicifacies and An. stephensi with 3 min exposure and after 24 h recovery period. Against Culex quinquefasciatus and housefly 100% mortality was obtained after 30 min of exposure period. Intervention with the ZeroFly plastic sheets resulted in almost complete reduction in the resting density of An. culicifacies and An. stephensi, the two major malaria vectors and also in the reduction of malaria cases in ZeroFly camps as compared to control camps. The ZeroFly plastic sheeting was found to be safe for human. Barring some complaints of skin irritation and itching, which were temporary in nature, no adverse health effects were reported by the users. The community acceptance was high.

CONCLUSION

Results of the present study revealed that ZeroFly® plastic sheeting is highly effective in reducing the indoor resting density of mosquitoes, man -vector contact and malaria incidences in labour populations living in temporary shelters.

CXCL4 and CXCL10 predict risk of fatal cerebral malaria

Plasmodium falciparum in a subset of patients can lead to a diffuse encephalopathy known as cerebral malaria (CM). Despite treatment, mortality caused by CM can be as high as 30% while 10% of survivors of the disease may experience short- and long-term neurological complications. The pathogenesis of CM involves alterations in cytokine and chemokine expression, local inflammation, vascular injury and repair processes. These diverse factors have limited the rate of discovery of prognostic predictors of fatal CM. Identification of reliable early predictors of CM severity will enable clinicians to adjust this risk with appropriate management of CM. Recent studies revealed that elevated levels of CXCL10 expression in cerebrospinal fluid and peripheral blood plasma independently predicted severe and fatal CM. CXCR3, a promiscuous receptor of CXCL10, plays an important role in pathogenesis of mouse model of CM. In this study the role of corresponding CXCR3 ligands (CXCL11, CXCL10, CXCL9 & CXCL4) in fatal or severe CM was evaluated by comparing their levels in 16 healthy control (HC), 26 mild malaria (MM), 26 cerebral malaria survivors (CMS) and 12 non-survivors (CMNS) using enzyme linked immunosorbent assay (ELISA). Levels of CXCL4 and CXCL10 were significantly elevated in CMNS patients (p < 0.05) when compared with HC, MM and CMS. Elevated plasma levels of CXCL10 and CXCL4 were tightly associated with CM mortality. Receiver Operating Characteristic (ROC) curve analysis revealed that CXCL4 and CXCL10 can discriminate CMNS from MM (p < 0.0001) and CMS (p < 0.0001) with an area under the curve (AUC) = 1. These results suggest that CXCL4 and CXCL10 play a prominent role in pathogenesis of CM associated death and may be used as functional or surrogate biomarkers for predicting CM severity.

Comparative efficacy of two poeciliid fish in indoor cement tanks against chikungunya vector Aedes aegypti in villages in Karnataka, India

BACKGROUND

In 2006, severe outbreaks of Aedes aegypti-transmitted chikungunya occurred in villages in Karnataka, South India. We evaluated the effectiveness of combined information, education and communication (IEC) campaigns using two potential poeciliid larvivorous fish guppy (Poecilia reticulata) and mosquitofish (Gambusia affinis), in indoor cement tanks for Aedes larval control.

METHODS

Trials were conducted in two villages (Domatmari and Srinivaspura) in Tumkur District from March to May 2006 for Poecilia and one village (Balmanda) in Kolar District from July to October 2006 for Gambusia. A survey on knowledge, attitude and practice (KAP) on chikungunya was initially conducted and IEC campaigns were performed before and after fish release in Domatmari (IEC alone, followed by IEC + Poecilia) and Balmanda (IEC + Gambusia). In Srinivaspura, IEC was not conducted. Larval surveys were conducted at the baseline followed by one-week and one-month post-intervention periods. The impact of fish on Aedes larvae and disease was assessed based on baseline and post-intervention observations.

RESULTS

Only 18% of respondents knew of the role of mosquitoes in fever outbreaks, while almost all (n = 50 each) gained new knowledge from the IEC campaigns. In Domatmari, IEC alone was not effective (OR 0.54; p = 0.067). Indoor cement tanks were the most preferred Ae. aegypti breeding habitat (86.9%), and had a significant impact on Aedes breeding (Breteau Index) in all villages in the one-week period (p < 0.001). In the one-month period, the impact was most sustained in Domatmari (OR 1.58, p < 0.001) then Srinivaspura (OR 0.45, p = 0.063) and Balmanda (OR 0.51, p = 0.067). After fish introductions, chikungunya cases were reduced by 99.87% in Domatmari, 65.48% in Srinivaspura and 68.51% in Balmanda.

CONCLUSIONS

Poecilia exhibited greater survival rates than Gambusia (86.04 vs.16.03%) in cement tanks. Neither IEC nor Poecilia alone was effective against Aedes (p > 0.05). We conclude that Poecilia + IEC is an effective intervention strategy. The operational cost was 0.50 (US$ 0.011, 1 US$= 47) per capita per application. Proper water storage practices, focused IEC with Poecilia introductions and vector sanitation involving the local administration and community, is suggested as the best strategy for Aedes control.

A proteogenomic analysis of Anopheles gambiae using high-resolution Fourier transform mass spectrometry

Anopheles gambiae is a major mosquito vector responsible for malaria transmission, whose genome sequence was reported in 2002. Genome annotation is a continuing effort, and many of the approximately 13,000 genes listed in VectorBase for Anopheles gambiae are predictions that have still not been validated by any other method. To identify protein-coding genes of An. gambiae based on its genomic sequence, we carried out a deep proteomic analysis using high-resolution Fourier transform mass spectrometry for both precursor and fragment ions. Based on peptide evidence, we were able to support or correct more than 6000 gene annotations including 80 novel gene structures and about 500 translational start sites. An additional validation by RT-PCR and cDNA sequencing was successfully performed for 105 selected genes. Our proteogenomic analysis led to the identification of 2682 genome search-specific peptides. Numerous cases of encoded proteins were documented in regions annotated as intergenic, introns, or untranslated regions. Using a database created to contain potential splice sites, we also identified 35 novel splice junctions. This is a first report to annotate the An. gambiae genome using high-accuracy mass spectrometry data as a complementary technology for genome annotation.

Status of pesticide management in the practice of vector control: a global survey in countries at risk of malaria or other major vector-borne diseases

Background

It is critical that vector control pesticides are used for their acceptable purpose without causing adverse effects on health and the environment. This paper provides a global overview of the current status of pesticides management in the practice of vector control.

Methods

A questionnaire was distributed to WHO member states and completed either by the director of the vector-borne disease control programme or by the national manager for vector control. In all, 113 countries responded to the questionnaire (80% response rate), representing 94% of the total population of the countries targeted.

Results

Major gaps were evident in countries in pesticide procurement practices, training on vector control decision making, certification and quality control of pesticide application, monitoring of worker safety, public awareness programmes, and safe disposal of pesticide-related waste. Nevertheless, basic conditions of policy and coordination have been established in many countries through which the management of vector control pesticides could potentially be improved. Most countries responded that they have adopted relevant recommendations by the WHO.

Conclusions

Given the deficiencies identified in this first global survey on public health pesticide management and the recent rise in pesticide use for malaria control, the effectiveness and safety of pesticide use are being compromised. This highlights the urgent need for countries to strengthen their capacity on pesticide management and evidence-based decision making within the context of an integrated vector management approach.

Field evaluation of lambda-cyhalothrin (ICON 10 CS) indoor residual spraying against Anopheles culicifacies in India

BACKGROUND & OBJECTIVES

Field trials of lambda-cyhalothrin 10 CS (ICON 10 CS) in indoor residual spraying (IRS) with 25 mg a.i./m2 against Anopheles culicifacies was undertaken vs malathion IRS (25% WP-2 g a.i./m2) in Tumkur district, Karnataka; vs deltamethrin IRS (2.5% WP-20 mg a.i./m2) in Dharmapuri district; and vs lambda-cyhalothrin (10 WP-25 mg a.i./m2) in Ramanathapuram district, Tamil Nadu, India.

METHODS

Spray operations in the experimental villages were done by the National Institute of Malaria Research (NIMR) and in the control villages by the respective State Health Department staff. Persistence of efficacy of insecticide sprayed in villages was assessed by contact bioassays against vector mosquitoes. Entomological indicators such as per structure density, parity rates of vector mosquitoes and sporozoite rates were measured in all the three study areas using standard procedures. Mass blood surveys and active fever case detections were carried out in experimental and control villages to study the impact of IRS on malaria transmission.

RESULTS

Persistence of effectiveness of ICON 10 CS was observed up to 2-3 months in all the three study areas. ICON 10 CS was found effective at par with or better than the insecticides used in the national programme in reducing the mosquito densities and in interrupting malaria transmission in the study villages. Vector density, parity rates and malaria cases considerably reduced in the ICON 10 CS-sprayed villages.

CONCLUSION

Field trials at three sites have established that ICON 10 CS formulation was relatively more effective than malathion 25% WP, deltamethrin 2.5% WP and lambda-cyhalothrin 10% WP in some evaluation parameters like indoor resting mosquitoes, parity rates in vector mosquitoes and persistence of effectiveness. It can be used for IRS for malaria vector control with two rounds of spray at an interval of 3 months for curtailing the malaria transmission and an additional round is recommended in perennial malaria transmission areas.

Chlorfenapyr: a new insecticide with novel mode of action can control pyrethroid resistant malaria vectors

BACKGROUND

Malaria vectors have acquired widespread resistance to many of the currently used insecticides, including synthetic pyrethroids. Hence, there is an urgent need to develop alternative insecticides for effective management of insecticide resistance in malaria vectors. In the present study, chlorfenapyr was evaluated against Anopheles culicifacies and Anopheles stephensi for its possible use in vector control.

METHODS

Efficacy of chlorfenapyr against An. culicifacies and An. stephensi was assessed using adult bioassay tests. In the laboratory, determination of diagnostic dose, assessment of residual activity on different substrates, cross-resistance pattern with different insecticides and potentiation studies using piperonyl butoxide were undertaken by following standard procedures. Potential cross-resistance patterns were assessed on field populations of An. culicifacies.

RESULTS

A dose of 5.0% chlorfenapyr was determined as the diagnostic concentration for assessing susceptibility applying the WHO tube test method in anopheline mosquitoes with 2 h exposure and 48 h holding period. The DDT-resistant/malathion-deltamethrin-susceptible strain of An. culicifacies species C showed higher LD50 and LD99 (0.67 and 2.39% respectively) values than the DDT-malathion-deltamethrin susceptible An. culicifacies species A (0.41 and 2.0% respectively) and An. stephensi strains (0.43 and 2.13% respectively) and there was no statistically significant difference in mortalities among the three mosquito species tested (p > 0.05). Residual activity of chlorfenapyr a.i. of 400 mg/m2 on five fabricated substrates, namely wood, mud, mud+lime, cement and cement + distemper was found to be effective up to 24 weeks against An. culicifacies and up to 34 weeks against An. stephensi. No cross-resistance to DDT, malathion, bendiocarb and deltamethrin was observed with chlorfenapyr in laboratory-reared strains of An. stephensi and field-caught An. culicifacies. Potentiation studies demonstrated the antagonistic effect of PBO.

CONCLUSION

Laboratory studies with susceptible and resistant strains of An. culicifacies and An. stephensi, coupled with limited field studies with multiple insecticide-resistant An. culicifacies have shown that chlorfenapyr can be a suitable insecticide for malaria vector control, in multiple-insecticide-resistant mosquitoes especially in areas with pyrethroid resistant mosquitoes.

Arterolane, a new synthetic trioxolane for treatment of uncomplicated Plasmodium falciparum malaria: a phase II, multicenter, randomized, dose-finding clinical trial

BACKGROUND

Drug-resistant Plasmodium falciparum malaria necessitates development of novel drugs for treatment.The present study assessed the efficacy and safety of 3 dose levels of arterolane (RBx 11160), a synthetic trioxolane, for treatment of acute uncomplicated falciparum malaria.

METHODS

In this randomized, double-blind, multicenter, parallel-group, dose-finding, phase II trial, 230 patients from 4 centers in Thailand, India, and Tanzania (mainland and Zanzibar) received either 50 mg (n=78), 100mg (n=76), or 200 mg (n=76) of arterolane once daily for 7 days. Patients (aged 13-65 years) with asexual parasite density of 1000-100,000 parasites/microL were included and were followed up for 28 days. The median time to 90% parasite clearance (PC90) was evaluated.

RESULTS

The median PC90 was longer in the group receiving the 50-mg dose (19.4 h), compared with the groups receiving the 100-mg dose (12.8 h) and 200-mg dose (12.6 h) (P < .01). The polymerase chain reaction-corrected adequate clinical and parasitological responses on day 28 were 63%, 71%, and 72% for the groups receiving the 50-mg, 100-mg, and 200-mg doses, respectively, by intention-to-treat analysis (odds ratio, 1.55; 95%confidence interval, 0.78-3.06, for comparison of the 200-mg and 50-mg dose groups). Treatment was generally well tolerated. No patient died or experienced any serious adverse event. Mild complaints were reported in <10%of the patients and were similar in the 3 groups. Biochemistry and hematological analyses did not show any signof drug toxicity in any patient.

CONCLUSION

Arterolane at daily doses of 100 and 200 mg is a rapidly acting, effective, and safe synthetic antimalarial drug, which may potentially represent an alternative to artemisinin derivatives in antimalarial combination therapy.

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT00362050.

Community awareness, perceptions, acceptability and preferences for using LLIN against malaria in villages of Uttar Pradesh, India

BACKGROUND & OBJECTIVES

Long-lasting insecticidal nets (LLINs) have been introduced in India recently into the vector control programme. A study was undertaken to assess the community perception regarding use of LLIN, their acceptability, collateral benefits, etc. in certain villages of District Gautam Budh Nagar, Uttar Pradesh, India where LLINs are in use by the community.

METHOD

A randomized community-based survey was undertaken during April- May 2009 covering 596 respondents in LLIN villages where LLINs have been distributed along with 307 respondents in untreated net villages where untreated nets were distributed using structured questionnaire. Qualitative data were collected and the difference in proportion was calculated by z-test.

RESULTS

A substantial number of respondents had good knowledge of the symptoms of malaria. According to respondents, LLINs were very much effective in bringing down the malaria incidence in their families. About 98.3% of the respondents asserted the use of LLINs as their use not only reduced the number of mosquitoes as well as other non-target insects, but also reduced the malaria incidence. About 93.2% of the respondents were ready to purchase LLINs if available at nominal prices. All the respondents were satisfied about the performance of the LLINs in reducing the mosquito nuisance, safety of use and collateral benefits in LLIN villages.

CONCLUSION

LLINs are safe, socially acceptable and should be promoted for vector control to reduce the disease burden in the communities.

Wash-resistance and field evaluation of alphacypermethrin treated long-lasting insecticidal net (Interceptor) against malaria vectors Anopheles culicifacies and Anopheles fluviatilis in a tribal area of Orissa, India

A field trial was conducted on the efficacy of Interceptor nets-a long-lasting insecticidal net (LLN) factory treated with alphacypermethrin 0.667% (w/w) corresponding to 200mg/m(2), against malaria vectors Anopheles culicifacies and Anopheles fluviatilis in one of the highly endemic areas of Orissa. The study area comprised 19 villages which were randomized into three clusters and designated as Interceptor net cluster, untreated net cluster, and no net cluster. Baseline studies showed that both the vector species An. culicifacies and An. fluviatilis were 100% susceptible to alphacypermethrin. Results of wash-resistance and bio-efficacy of Interceptor nets showed 100% mortality in An. culicifacies and An. fluviatilis even after 20 washings. Bioassays on the Interceptor nets while in use in the field conditions showed a knockdown effect on 70-90% mosquitoes during different months of intervention after 3 min of exposure and 100% mortality was recorded after 24h of recovery period. The median knockdown time for these species ranged between 4.10-5.25 min and 4.00-5.00 min respectively during intervention period. In Interceptor net study area, there was a significant reduction of 88.9, 96.3 and 90.6% in the entry rate of An. culicifacies, An. fluviatilis and other anopheline species respectively with an over all reduction of 87.5% in total mosquitoes. The overall feeding success rate of mosquitoes in the trial villages was only 12.8% in comparison to 35.0 and 78.8% in villages with untreated nets and no nets respectively. A significant reduction was also recorded in parity rate and human blood index of vector species in Interceptor net area. The results of the study showed that Interceptor nets are effective against the malaria vectors and may be used as a suitable intervention strategy in high-risk areas.

Persistent transmission of malaria in Garo hills of Meghalaya bordering Bangladesh, north-east India

Background

Malaria is endemic in Garo hills of Meghalaya, and death cases are reported annually. Plasmodium falciparum is the major parasite, and is solely responsible for each malaria-attributable death case. Garo hills are categorized high-risk for drug-resistant malaria; however, there exists no data on malaria transmitting mosquitoes prevalent in the region. Included in this report are entomological observations with particular reference to vector biology characteristics for devising situation specific intervention strategies for disease transmission reduction.

Methods

The epidemiological data of the West Garo hills have been reviewed retrospectively for 2001-2009 to ascertain the disease transmission profile given the existing interventions. Point prevalence study was conducted in Dalu Community Health Centre that lies in close proximity to international border with Bangladesh to ascertain the true prevalence of malaria, and parasite species. Mosquito collections were made in human dwellings of malaria endemic villages aiming at vector incrimination, and to study relative abundance, resting and feeding preferences, and their present susceptibility status to DDT.

Results

Investigations revealed that the West Garo hill district is co-endemic for Plasmodium falciparum and Plasmodium vivax, but P. falciparum was the predominant infection (> 82%). Malaria transmission was perennial and persistent with seasonal peak during May-July corresponding to months of high rainfall. Entomological collections revealed that Anopheles minimus was the predominant species that was incriminated by detection of sporozoites in salivary glands (infection rate 2.27%), and was ascertained to be fully susceptible to DDT.

Conclusion

For the control of malaria, improved diagnosis and sustained supply of drugs for artemisinin-based combination therapy are strongly advocated, which should be enforced for treatment of every single case of P. falciparum. Greater political commitment is called for organized vector control operations along border/high-risk areas to contain the spread of drug-resistant malaria, and averting impending disease outbreaks.

Availability and utilization of malaria prevention strategies in pregnancy in eastern India

Background

Malaria in pregnancy in India, as elsewhere, is responsible for maternal anemia and adverse pregnancy outcomes such as low birth weight and preterm birth.

It is not known whether prevention and treatment strategies for malaria in pregnancy (case management, insecticide-treated bednets, intermittent preventive therapy) are widely utilized in India.

Methods

This cross-sectional study was conducted during 2006-2008 in two states of India, Jharkhand and Chhattisgarh, at 7 facilities representing a range of rural and urban populations and areas of more versus less stable malaria transmission. 280 antenatal visits (40/site) were observed by study personnel coupled with exit interviews of pregnant women to assess emphasis upon, availability and utilization of malaria prevention practices by health workers and pregnant women. The facilities were assessed for the availability of antimalarials, lab supplies and bednets.

Results

All participating facilities were equipped to perform malaria blood smears; none used rapid diagnostic tests. Chloroquine, endorsed for chemoprophylaxis during pregnancy by the government at the time of the study, was stocked regularly at all facilities although the quantity stocked varied. Availability of alternative antimalarials for use in pregnancy was less consistent. In Jharkhand, no health worker recommended bednet use during the antenatal visit yet over 90% of pregnant women had bednets in their household. In Chhattisgarh, bednets were available at all facilities but only 14.4% of health workers recommended their use. 40% of the pregnant women interviewed had bednets in their household. Only 1.4% of all households owned an insecticide-treated bednet; yet 40% of all women reported their households had been sprayed with insecticide. Antimalarial chemoprophylaxis with chloroquine was prescribed in only 2 (0.7%) and intermittent preventive therapy prescribed in only one (0.4%) of the 280 observed visits.

Conclusions

A disconnect remains between routine antenatal practices in India and known strategies to prevent and treat malaria in pregnancy. Prevention strategies, in particular the use of insecticide-treated bednets, are underutilized. Gaps highlighted by this study combined with recent estimates of the prevalence of malaria during pregnancy in these areas should be used to revise governmental policy and target increased educational efforts among health care workers and pregnant women.

Persistence of DDT, malathion & deltamethrin resistance in Anopheles culicifacies after their sequential withdrawal from indoor residual spraying in Surat district, India

BACKGROUND & OBJECTIVES

Under the national antimalaria programme DDT was introduced in early 1950s for vector control and later hexachloro cyclohexane (HCH) followed by malathion and recently synthetic pyrethroids in 1990s to manage the insecticide resistance in Anopheles culicifacies. Subsequent replacement led to development of multiple resistances in An. culicifacies in Surat district in Gujarat State. Indoor residual spray (IRS) was completely withdrawn in southern villages in Surat in 2002. This study was undertaken in these areas to study the persistence of resistance to DDT, malathion and deltamethrin after sequential withdrawal of IRS with these insecticides at different times.

METHODS

Susceptibility tests on An. culicifacies were conducted using standard WHO methods and kits. Mortality, knockdown time and lethal times were calculated for An. culicifacies exposed to WHO prescribed diagnostic concentrations of different insecticide impregnated papers.

RESULTS

Persistence of DDT-resistance was observed even after 30 yr of its withdrawal from IRS. Similarly, persistence of malathion resistance was also observed after 9 yr of its withdrawal from IRS, while reversal of deltamethrin-resistance was observed very fast within 2-3 yr after its withdrawal from IRS in 2002.

INTERPRETATION & CONCLUSION

Present data indicate that the quantum of reversion of insecticide resistance in a population is relative and depends on the genetic stability of the respective resistance genes in the mosquitoes. In the present study withdrawal of pyrethroid-IRS resulted in increased susceptibility against pyrethroids alone and was independent of existence of resistance to insecticides of other groups. This study emphasizes that appropriate rotation of different insecticides; including carbamates may prevent or delay the onset of resistance.

Elimination of neglected tropical diseases in the South-East Asia Region of the World Health Organization

The neglected tropical diseases (NTDs), which affect the very poor, pose a major public health problem in the South-East Asia Region of the World Health Organization (WHO). Although more than a dozen NTDs affect the region, over the past five years four of them in particular - leprosy, lymphatic filariasis, visceral leishmaniasis (kala-azar) and yaws - have been targeted for elimination. These four were selected for a number of reasons. First, they affect the WHO South-East Asia Region disproportionately. For example, every year around 67% of all new leprosy cases and 60% of all new cases of visceral leishmaniasis worldwide occur in countries of the region, where as many as 850 million inhabitants are at risk of contracting lymphatic filariasis. In addition, several epidemiological, technological and historical factors that are unique to the region make each of these four diseases amenable to elimination. Safe and effective tools and interventions to achieve these targets are available and concerted efforts to scale them up, singly or in an integrated manner, are likely to lead to success. The World Health Assembly and the WHO Regional Committee, through a series of resolutions, have already expressed regional and global commitments for the elimination of these diseases as public health problems. Such action is expected to have a quick and dramatic impact on poverty reduction and to contribute to the achievement of the Millennium Development Goals. This paper reviews the policy rationale for disease control in the WHO South-East Asia Region, the progress made so far, the lessons learnt along the way, and the remaining challenges and opportunities.

Reduced susceptibility to selected synthetic pyrethroids in urban malaria vector Anopheles stephensi: a case study in Mangalore city, South India

BACKGROUND

Synthetic pyrethroids are potent insecticides most commonly used in the vector control programme. These are applied for indoor residual sprays, space sprays and in impregnated bed nets. Resistance reduces the efficacy of insecticides. Thus, the susceptibility status of the target vector(s) is monitored routinely to select the effective ones. A study was undertaken in a malaria endemic coastal city Mangalore, Karnataka, South India, against the known malaria vector Anopheles stephensi.

METHODS

The susceptibility status was assessed at diagnostic doses of DDT (4%), malathion (5%), deltamethrin (0.05%), cyfluthrin (0.15%), alphacypermethrin (0.10%), lambdacyhalothrin (0.05%) and permethrin (0.75%) using the standard WHO tube test method during October/November 2006.

RESULTS

Anopheles stephensi was resistant to malathion by 54.9%, but tolerant to deltamethrin by 86.1%, cyfluthrin 95.5% and alphacypermethrin 90.6%, whereas it was susceptible to DDT by 98.1%, lambdacyhalothrin 98.6% and permethrin 100.0%, respectively. The KDT50 and KDT95 values for these insecticides also showed the similar responses.

CONCLUSION

Susceptibility of An. stephensi to DDT is an important finding as this has never been used in Mangalore city, whereas its rural counterpart Anopheles culicifacies is widely resistant to this insecticide. The study explores the selection and rotation of the appropriate insecticide molecule even within the same group for effective vector management.

Spatio-temporal variations in adult density, abdominal status & indoor resting pattern of Culex quinquefasciatus Say in Panaji, Goa, India

BACKGROUND & OBJECTIVES

Goa is one of the filariasis endemic states of India. However, information on density pattern and resting behavior of Culex quinquefasciatus Say, the principal vector of filariasis in Goa is lacking. Therefore, current longitudinal study was undertaken to investigate these aspects.

METHODS

Panaji was divided into six zones and a total of 240 man hours were spent in 60 fixed catching sites to collect the adult Cx. quinquefasciatus mosquitoes on fortnightly basis from indoor resting sites during 2005-06. The female mosquitoes were classified as unfed, fed, semi-gravid and gravid to ascertain the resting behavior of Cx. quinquefasciatus adults. The data were analysed to evaluate the spatio-temporal variations in adult density, abdominal status and indoor resting sites and linked to meteorological variables like temperature, relative humidity, rainfall and number of rainy days.

RESULTS

Cx. quinquefasciatus adults were prevalent perennially in Panaji with highest per man hour density of females (48.6) in February and the lowest density (6.6) in September. Monthly variations in the densities between different months was significant (F=15.3; P<0.05). Rainfall significantly influenced the population of Cx. quinquefasciatus (t=2.63; P<0.05). Fed group and semi-gravid group showed a strong correlation with the relative humidity (P<0.05), rain fall (P<0.05) and number of rainy days (P<0.05). 62.4 per cent of females and 65.1 per cent of males preferred to rest on hanging objects. Spatio-temporal variations in the number of Cx. quinquefasciatus females and males resting on different sites and also the variations in different sites (P<0.05) were significant.

INTERPRETATION & CONCLUSION

The density of female Cx. quinquefasciatus encountered in all the months was higher than the estimated tolerated level of density of 34 per ten man hours up to which there is no risk of filariasis transmission. The strong correlation between the abdominal conditions and relative humidity, rainfall and number of rainy days imply that these meteorological variables significantly influenced the feeding and fecundity of the species. 85.3 per cent of the indoor resting population comprising of fed, semi-gravid and gravid females confirmed the endophilic nature of the species. The preferential resting behavior of both females and males on hanging objects suggest that use of insecticide treated long-lasting bed nets as personal protective measure can be exploited to reduce the density of the vector species.

Molecular evidence of misidentification of Anopheles minimus as Anopheles fluviatilis in Assam (India)

Anophelesminimus s.l. and Anophelesfluviatilis s.l., two closely related taxa, are reported vectors of malaria in Assam state of India. We determined the DNA sequences of morphologically identified A. minimus s.l. and A. fluviatilis s.l. collected from the Kamrup district in Assam, for two rDNA loci-internal transcribed spacer 2 (ITS2) and D3 domain of 28S rDNA (28S-D3). Analysis of rDNA data revealed that the sequences of both the morphologically identified A. minimus s.l. and A. fluviatilis s.l. from Assam are identical, homologous to the sequences of A. minimus s.s. (former species A) and different from that of all the reported members of the Fluviatilis Complex (species S, T and U). This indicates that A. fluviatilis s.l. being reported in Kamrup district, Assam, in low density, mostly during January to April, is actually a hypermelanic and seasonal variant of A. minimus. It was also found that the banding pattern on chromosome arm 2 (which bears species-diagnostic inversions for the Fluviatilis Complex) of A. minimus and of A. fluviatilis s.l. from Assam is homosequential with A. fluviatilis species U suggesting that probably previously described A. fluviatilis U from Assam were also A. minimus.

Adulticidal activity of essential oil of Lantana camara leaves against mosquitoes

BACKGROUND & OBJECTIVES

Development of insect resistance to synthetic pesticides, high operational cost and environmental pollution have created the need for developing alternative approaches to control vector-borne diseases. In the present study we have investigated the insecticidal activity of essential oil isolated from the leaves of Lantana camara against mosquito vectors.

METHODS

Essential oil was isolated from the leaves of L. camara using hydro-distillation method. Bioassay test was carried out by WHO method for determination of adulticidal activity against mosquitoes. Different compounds were identified by gas chromatography-mass spectrometry analysis.

RESULTS

LD(50) values of the oil were 0.06, 0.05, 0.05, 0.05 and 0.06 mg/cm(2) while LD(90) values were 0.10, 0.10, 0.09, 0.09 and 0.10 mg/cm(2) against Ae. aegypti, Cx. quinquefasciatus, An. culicifacies, An. fluvialitis and An. stephensi respectively. KDT(50) of the oil were 20, 18, 15, 12, and 14 min and KDT(90) values were 35, 28 25, 18, 23 min against Ae. aegypti, Cx. quinquefasciatus, An. culicifacies, An. fluviatilis and An. stephensi, respectively on 0.208 mg/cm(2) impregnated paper. Studies on persistence of essential oil of L. camara on impregnated paper revealed that it has more adulticidal activity for longer period at low storage temperature. Gas chromatographic-mass spectrometric analysis of essential oil showed 45 peaks. Caryophyllene (16.37%), eucalyptol (10.75%), alpha-humelene (8.22%) and germacrene (7.41%) were present in major amounts and contributed 42.75 per cent of the total constituents.

INTERPRETATION & CONCLUSIONS

Essential oil from the leaves of L. camara possesses adulticidal activity against different mosquito species that could be utilized for development of oil-based insecticide as supplementary to synthetic insecticides.

Evidence of selective sweeps in genes conferring resistance to chloroquine and pyrimethamine in Plasmodium falciparum isolates in India

Treatment of Plasmodium falciparum is complicated by the emergence and spread of parasite resistance to many of the first-line drugs used to treat malaria. Antimalarial drug resistance has been associated with specific point mutations in several genes, suggesting that these single nucleotide polymorphisms can be useful in tracking the emergence of drug resistance. In India, P. falciparum infection can manifest itself as asymptomatic, mild, or severe malaria, with or without cerebral involvement. We tested whether chloroquine- and antifolate drug-resistant genotypes would be more commonly associated with cases of cerebral malaria than with cases of mild malaria in the province of Jabalpur, India, by genotyping the dhps, dhfr, pfmdr-1, and pfcrt genes using pyrosequencing, direct sequencing, and real-time PCR. Further, we used microsatellites surrounding the genes to determine the origins and spread of the drug-resistant genotypes in this area. Resistance to chloroquine was essentially fixed, with 95% of the isolates harboring the pfcrt K76T mutation. Resistant genotypes of dhfr, dhps, and pfmdr-1 were found in 94%, 17%, and 77% of the isolates, respectively. Drug-resistant genotypes were equally likely to be associated with cerebral malaria as with mild malaria. We found evidence of a selective sweep in pfcrt and, to a lesser degree, in dhfr, indicating high levels of resistance to chloroquine and evolving resistance to pyrimethamine. Microsatellites surrounding pfcrt indicate that the resistant genotypes (SVMNT) were most similar to those found in Papua New Guinea.

Climate change and threat of vector-borne diseases in India: are we prepared?

It is unequivocal that climate change is happening and is likely to expand the geographical distribution of several vector-borne diseases, including malaria and dengue etc. to higher altitudes and latitudes. India is endemic for six major vector-borne diseases (VBD) namely malaria, dengue, chikungunya, filariasis, Japanese encephalitis and visceral leishmaniasis. Over the years, there has been reduction in the incidence of almost all the diseases except chikungunya which has re-emerged since 2005. The upcoming issue of climate change has surfaced as a new threat and challenge for ongoing efforts to contain vector-borne diseases. There is greater awareness about the potential impacts of climate change on VBDs in India and research institutions and national authorities have initiated actions to assess the impacts. Studies undertaken in India on malaria in the context of climate change impact reveal that transmission windows in Punjab, Haryana, Jammu and Kashmir and north-eastern states are likely to extend temporally by 2-3 months and in Orissa, Andhra Pradesh and Tamil Nadu there may be reduction in transmission windows. Using PRECIS model (driven by HadRM2) at the resolution of 50 x 50 Km for daily temperature and relative humidity for year 2050, it was found that Orissa, West Bengal and southern parts of Assam will still remain malarious and transmission windows will open up in Himachal Pradesh and north-eastern states etc. Impact of climate change on dengue also reveals increase in transmission with 2 C rise in temperature in northern India. Re-emergence of kala-azar in northern parts of India and reappearance of chikungunya mainly in southern states of India has also been discussed. The possible need to address the threat and efforts made in India have also been highlighted. The paper concludes with a positive lead that with better preparedness threat of climate change on vector-borne diseases may be negated.

Modulation of apoptosis against P. falciparum by low dose radiation in human PBMCs

BACKGROUND

Implications of low dose radiation (LDR) have been well reported in cancer therapy but data is scanty on the therapeutic application of LDR in infectious diseases.

METHODOLOGY

Human peripheral blood mononuclear cells (PBMCs) were cultured and exposed to 0.07 Gy. P. falciparum infected RBCs were mixed with the PBMCs after five hours of irradiation. Thereafter, PBMCs were monitored for micronuclei and apoptosis.

RESULTS

The low dose pre-irradiated PBMCs which were subsequently challenged with parasite, showed a reduction in micronuclei frequency and apoptosis as compared to controls.

CONCLUSION

LDR inhibited apoptosis against P. falciparum in human PBMCs.