Malaria in North-East India: Importance and Implications in the Era of Elimination

Mapping malaria vectors and insecticide resistance in a high-endemic district of Haryana, India: implications for vector control strategies

BACKGROUND

Achieving effective control and elimination of malaria in endemic regions necessitates a comprehensive understanding of local mosquito species responsible for malaria transmission and their susceptibility to insecticides.

METHODS

The study was conducted in the highly malaria prone Ujina Primary Health Center of Nuh (Mewat) district of Haryana state of India. Monthly entomological surveys were carried out for adult mosquito collections via indoor resting collections, light trap collections, and pyrethrum spray collections. Larvae were also collected from different breeding sites prevalent in the region. Insecticide resistance bioassay, vector incrimination, blood meal analysis was done with the collected vector mosquitoes.

RESULTS

A total of 34,974 adult Anopheles mosquitoes were caught during the survey period, out of which Anopheles subpictus was predominant (54.7%). Among vectors, Anopheles stephensi was predominant (15.5%) followed by Anopheles culicifacies (10.1%). The Human Blood Index (HBI) in the case of An. culicifacies and An. stephensi was 6.66 and 9.09, respectively. Vector incrimination results revealed Plasmodium vivax positivity rate of 1.6% for An. culicifacies. Both the vector species were found resistant to DDT, malathion and deltamethrin.

CONCLUSION

The emergence of insecticide resistance in both vector species, compromises the effectiveness of commonly used public health insecticides. Consequently, the implementation of robust insecticide resistance management strategies becomes imperative. To effectively tackle the malaria transmission, a significant shift in vector control strategies is warranted, with careful consideration and adaptation to address specific challenges encountered in malaria elimination efforts.

Determinants of malaria prevention and control at household level in Assam: An analysis of data using composite index

Background

Malaria prevention and control is a major public health problem of tropical countries including India. Usage of insecticide-treated bed nets, and early treatment especially in high-risk areas are the crucial factors for the malaria prevention at household levels. This study aimed to determine the crucial factors associated with malaria prevention at households' level such as household's characteristics, education, knowledge and awareness, insecticide treated bed nets usage, early treatment etc.

Methods

Data of 1989 households was used from the cross-sectional survey of malaria-endemic areas of Assam. Principal component analysis and multinomial logistic regression model were used to compute the composite scores of malaria awareness and prevention practices, and to estimate the associated factors with malaria prevention practices, respectively.

Results

The average age of household respondents were 41.1 ± 12.0 years and among them 71% were males. Almost 47% respondents were illiterate, and 38.6% of the respondents were farmers and 35% were employed. Multinomial logistic regression analysis indicates that malaria prevention practices are associated with age, education, religion, type of house and occupation of household heads and their level of malaria awareness among them. The prevention practices were significantly five times associated [Adjusted Rates Ratio (ARR): 5.0, 95% CI: 2.7-9.4] with the high level of malaria awareness compared with the low level of awareness. Overall, the level of prevention awareness, education, occupation, and house type related to the standard of living was significantly associated with the malaria prevention practices.

Conclusion

Malaria awareness and education are the key factors of malaria prevention practices that need to be accelerated for effective control of malaria. Malaria education and increasing awareness of people have a high impact on malaria prevention practices and their control.

Efficacy and safety of Artemisinin Combination Therapy for the treatment of uncomplicated Plasmodium falciparum malaria across international borders of India

BACKGROUND OBJECTIVES

Malaria due to Plasmodium falciparum (Pf) remains a major public threat in India. Artemisinin-based combination therapy (ACT) has been the country's first-line drug for uncomplicated Pf malaria. In 2013-2014, Artesunate plus sulfadoxine (AS+SP) was replaced by Artemether Lumefantrine (AL) as the first- line antimalarial in North East (NE) states of the country which are endemic for Pf malaria. Regular monitoring of antimalarial drugs is of utmost importance to achieve the goal of elimination. This study aimed to assess the efficacy and safety of ACT for treating uncomplicated Pf malaria in the NE states of India.

METHODS

A prospective study of 28-day follow-up was conducted to monitor the efficacy and safety of AL from 2018-2019 in four districts, Udalgiri, Meghalaya, Lawngtlai, and Dhalai of NE, India. The clinical and parasitological response and the polymorphism analysis of the Pfdhps, P/dhfr, and Pfkelch 13 gene were evaluated.

RESULTS

A total of 234 patients were enrolled in the study out of 216 patients who completed the follow-up to 28 days. One-hundred percent adequate clinical and parasitological responses (ACPR) were observed with polymerase chain reaction (PCR) correction. The genotype results suggest no recrudescence in the treatment-failure patients. The classical single nucleotide polymorphisms (SNP) in the Pfdhfr gene was S108N (94.9%), followed by C59R (91.5%), whereas, in the Pfdhps gene, the common SNP was A437G (79.6%), followed by S3436A. No associated or validated mutations were found in the propeller region of the PfKelch13 gene.

INTERPRETATION CONCLUSION

AL was efficacious and safe in uncomplicated P. falciparum malaria in North East India. In contrast, mutations in the genes responsible for sulfadoxine and pyrimethamine resistance have been fixed in northeast India's population.

Molecular Evidence of Wolbachia Species in Wild-Caught Aedes albopictus and Aedes aegypti Mosquitoes in Four States of Northeast India

Wolbachia, a Gram-negative intracellular bacterium, naturally infects many arthropods, including mosquito vectors responsible for the spread of arboviral diseases such as Zika, chikungunya, and dengue fever. Certain Wolbachia strains are involved in inhibiting arbovirus replication in mosquitoes, and this phenomenon is currently being studied to combat disease vectors. A study was conducted in four states in north-eastern India to investigate the presence of natural Wolbachia infection in wild-caught Aedes albopictus and Aedes aegypti mosquitoes, the established vectors of dengue. The detection of a Wolbachia infection was confirmed by nested PCR and sequencing in the two mosquito species Ae. aegypti and Ae. albopictus. Positivity rates observed in Ae. aegypti and Ae. albopictus pools were 38% (44 of 115) and 85% (41 of 48), respectively, and the difference was significant (chi-square = 28.3174, p = 0.00000010). Sequencing revealed that all detected Wolbachia strains belonged to supergroup B. Although Wolbachia infection in Ae. aegypti has been previously reported from India, no such reports are available from north-eastern India. Data on naturally occurring Wolbachia strains are essential for selecting the optimal strain for the development of Wolbachia-based control measures. This information will be helpful for the future application of Wolbachia-based vector control measures in this part of the country.

Nationwide spatiotemporal drug resistance genetic profiling from over three decades in Indian Plasmodium falciparum and Plasmodium vivax isolates

BACKGROUND

Drug resistance is a serious impediment to efficient control and elimination of malaria in endemic areas.

METHODS

This study aimed at analysing the genetic profile of molecular drug resistance in Plasmodium falciparum and Plasmodium vivax parasites from India over a ~ 30-year period (1993-2019). Blood samples of P. falciparum and/or P. vivax-infected patients were collected from 14 regions across India. Plasmodial genome was extracted and used for PCR amplification and sequencing of drug resistance genes in P. falciparum (crt, dhps, dhfr, mdr1, k13) and P. vivax (crt-o, dhps, dhfr, mdr1, k12) field isolates.

RESULTS

The double mutant pfcrt SVMNT was highly predominant across the country over three decades, with restricted presence of triple mutant CVIET from Maharashtra in 2012. High rates of pfdhfr-pfdhps quadruple mutants were observed with marginal presence of "fully resistant" quintuple mutant ACIRNI-ISGEAA. Also, resistant pfdhfr and pfdhps haplotype has significantly increased in Delhi between 1994 and 2010. For pfmdr1, only 86Y and 184F mutations were present while no pfk13 mutations associated with artemisinin resistance were observed. Regarding P. vivax isolates, the pvcrt-o K10 "AAG" insertion was absent in all samples collected from Delhi in 2017. Pvdhps double mutant SGNAV was found only in Goa samples of year 2008 for the first time. The pvmdr1 908L, 958M and 1076L mutations were highly prevalent in Delhi and Haryana between 2015 and 2019 at complete fixation. One nonsynonymous novel pvk12 polymorphism was identified (K264R) in Goa.

CONCLUSIONS

These findings support continuous surveillance and characterization of P. falciparum and P. vivax populations as proxy for effectiveness of anti-malarial drugs in India, especially for independent emergence of artemisinin drug resistance as recently seen in Africa.

Characterisation of Anopheles species composition and genetic diversity in Meghalaya, northeast India, using molecular identification tools

Malaria in India is declining, in part due to the use of long-lasting insecticide-treated nets (LLINs) and vector control. Historically, the north-eastern region of India has contributed ~10%-12% of the nation's malaria burden. The important mosquito vectors in northeast India have long been considered to be Anopheles baimaii and An. minimus, both associated with forest habitats. Local deforestation and increased rice cultivation, along with widespread LLIN use, may be changing vector species composition. Understanding if and how vector species composition is changing is critical to successful malaria control. In Meghalaya state, malaria is now at a low level of endemicity with occasional seasonal outbreaks. In a biodiverse setting like Meghalaya, where >24 Anopheles mosquito species have been recorded, accurate morphological identification of all species is logistically challenging. To accurately determine Anopheles species richness in the West Khasi Hills (WKH) and West Jaintia Hills (WJH) districts, adult and larval mosquitoes were collected and identified using molecular methods of allele-specific PCR and cytochrome oxidase I DNA barcoding. In 14 villages across both districts, we identified high species richness, 19 species in total. Molecular findings indicated that An. minimus and An. baimaii were rare, while four other species (An. maculatus, An. pseudowillmori, An. jeyporiensis and An. nitidus) were abundant. Anopheles maculatus was highly prevalent in WKH (39% of light trap collections) and An. pseudowillmori in WJH (45%). Larvae of these four species were found in rice fields, suggesting that land cover change is influencing species composition change. Our results suggest that rice fields might be contributing to the observed abundance of An. maculatus and An. pseudowillmori, which could be playing a role in malaria transmission, either independently due to their high abundance, or in combination with An. baimaii and/or An. minimus.

Impact assessment of Intensified Malaria Control Project in transitioning a high malaria-endemic district to a low-endemic district: an epidemiological aspect

Intensified Malaria Control Project (IMCP) was implemented in 2005 to control malaria in all North-Eastern and Odisha states of India. The present study aimed to investigate the impact of IMCP in reducing the malaria burden in Udalguri district, Assam state of North-East India. Malaria epidemiological data were obtained for IMCP intervention (Udalguri) and nonintervention district (West Singhbhumi, Jharkhand state). IMCP activities include introducing bi-valent rapid diagnostic kits (RDTs), Artemether-Lumefantrine drug in North-East India, long-lasting insecticidal nets (LLINs) distribution, and creating awareness programs about malaria in an intensified mode. The data revealed a significant decline in annual parasite incidence (API) from 14.94 (2005) to 2.61 (2018), -37% (95%CI: -57%, -19%, p = 001) after using LLINs in 2009 and -64% (95%CI: -116%, -14%, p = 013) after the introduction of RDTs in district Udalguri. Whereas control district showed a -28% (95%CI: -63%, 6.3%, p = 0.051) decrease in API using LLINs and a 10% (95%CI: -7.6%, 28%, p = 0.122) increase after the introduction of RDTs. Plasmodium falciparum (Pf) and P. vivax (Pv) were the major malarial parasites in Udalguri. Pv-malaria was much higher (71%) than Pf-malaria (29%) during the study period. An increasing trend of Pf cases was observed in Udalguri. Udalguri and Khoirabari BPHCs showed an overall reduction of 94% (95%CI: -143%, -45%, p = 0.001) and 84% (95%CI: -126%, -39%, p = 0.003), respectively; however, only a 10% (95%CI: -65%, -41%, p = 0.360) reduction in API was observed in Orang BPHC. An overall decrease in malaria indicates the effective implementation of vector and disease control strategies in the Udalguri district.

The synergistic effect of climatic factors on malaria transmission: a predictive approach for northeastern states of India

The northeast region of India is highlighted as the most vulnerable region for malaria. This study attempts to explore the epidemiological profile and quantify the climate-induced influence on malaria cases in the context of tropical states, taking Meghalaya and Tripura as study areas. Monthly malaria cases and meteorological data from 2011 to 2018 and 2013 to 2019 were collected from the states of Meghalaya and Tripura, respectively. The nonlinear associations between individual and synergistic effect of meteorological factors and malaria cases were assessed, and climate-based malaria prediction models were developed using the generalized additive model (GAM) with Gaussian distribution. During the study period, a total of 216,943 and 125,926 cases were recorded in Meghalaya and Tripura, respectively, and majority of the cases occurred due to the infection of Plasmodium falciparum in both the states. The temperature and relative humidity in Meghalaya and temperature, rainfall, relative humidity, and soil moisture in Tripura showed a significant nonlinear effect on malaria; moreover, the synergistic effects of temperature and relative humidity (SI=2.37, RERI=0.58, AP=0.29) and temperature and rainfall (SI=6.09, RERI=2.25, AP=0.61) were found to be the key determinants of malaria transmission in Meghalaya and Tripura, respectively. The developed climate-based malaria prediction models are able to predict the malaria cases accurately in both Meghalaya (RMSE: 0.0889; R²: 0.944) and Tripura (RMSE: 0.0451; R²: 0.884). The study found that not only the individual climatic factors can significantly increase the risk of malaria transmission but also the synergistic effects of climatic factors can drive the malaria transmission multifold. This reminds the policymakers to pay attention to the control of malaria in situations with high temperature and relative humidity and high temperature and rainfall in Meghalaya and Tripura, respectively.

Malaria hotspots and climate change trends in the hyper-endemic malaria settings of Mizoram along the India-Bangladesh borders

India has made tremendous progress in reducing malaria mortality and morbidity in the last decade. Mizoram State in North-East India is one of the few malaria-endemic regions where malaria transmission has continued to remain high. As Mizoram shares international borders with Bangladesh and Myanmar, malaria control in this region is critical for malaria elimination efforts in all the three countries. For identifying hotspots for targeted intervention, malaria data from 385 public health sub-centers across Mizoram were analyzed in the Geographic Information System. Almost all the sub-centers reporting high Annual Parasite Index (> 10) are located in Mizoram's districts that border Bangladesh. Getis-Ord G_i* statistic shows most of the sub-centers located along the Bangladesh border in the Lawngtlai and Lunglei districts to be the malaria hotspots. The hotspots also extended into the Mamit and Siaha districts, especially along the borders of Lawngtlai and Lunglei. Analysis of terrain, climatic, and land use/land cover datasets obtained from the Global Modelling and Assimilation Office and satellite images show Mizoram's western part (Lawngtlai, Lunglei, and Mamit districts) to experience similar topographic and climatic conditions as the bordering Rangamati district in the Chittagong division of Bangladesh. Climatic trends in this region from 1981 to 2021, estimated by the Mann-Kendall test and Sen's slope estimates, show an increasing trend in minimum temperature, relative humidity, rainfall, and the associated shift of climatic pattern (temperate to tropical monsoon) could facilitate malaria transmission. The quasi-Poisson regression model estimates a strong association (p < 0.001) between total malaria cases, temperature range, and elevation. The Kruskal-Wallis H test shows a statistically significant association between malaria cases and forest classes (p < 0.001). A regional coordination and strategic plan are required to eliminate malaria from this hyper-endemic malaria region of North-East India.

Weather integrated malaria prediction system using Bayesian structural time series model for northeast states of India

Malaria is an endemic disease in India and targeted to eliminate by the year 2030. The present study is aimed at understanding the epidemiological patterns of malaria transmission dynamics in Assam and Arunachal Pradesh followed by the development of a malaria prediction model using monthly climate factors. A total of 144,055 cases in Assam during 2011-2018 and 42,970 cases in Arunachal Pradesh were reported during the 2011-2019 period observed, and Plasmodium falciparum (74.5%) was the most predominant parasite in Assam, whereas Plasmodium vivax (66%) in Arunachal Pradesh. Malaria transmission showed a strong seasonal variation where most of the cases were reported during the monsoon period (Assam, 51.9%, and Arunachal Pradesh, 53.6%). Similarly, the malaria incidence was highest in the male population in both states (Asam, 55.75%, and Arunachal Pradesh, 51.43%), and the disease risk is also higher among the > 15 years age group (Assam, 61.7%, and Arunachal Pradesh, 67.9%). To predict the malaria incidence, Bayesian structural time series (BSTS) and Seasonal Auto-Regressive Integrated Moving Average with eXogenous factors (SARIMAX) models were implemented. A statistically significant association between malaria cases and climate variables was observed. The most influencing climate factors are found to be maximum and mean temperature with a 6-month lag, and it showed a negative association with malaria incidence. The BSTS model has shown superior performance on the optimal auto-correlated dataset (OAD) which contains auto-correlated malaria cases, cross-correlated climate variables besides malaria cases in both Assam (RMSE, 0.106; MAE, 0.089; and SMAPE, 19.2%) and Arunachal Pradesh (RMSE, 0.128; MAE, 0.122; and SMAPE, 22.6%) than the SARIMAX model. The findings suggest that the predictive performance of the BSTS model is outperformed, and it may be helpful for ongoing intervention strategies by governmental and nongovernmental agencies in the northeast region to combat the disease effectively.

Moderate Rainfall and High Humidity During the Monsoon Season, Negligence in Using Malaria Protection Methods and High Proportion of Mild Symptomatic Patients Were the Driving Forces for Upsurge of Malaria Cases in 2018 Among Tea Tribe Populations in Endemic Dolonibasti Health Sub-center, Udalguri District, Assam State, North-East India

Malaria elimination is a global priority, which India has also adopted as a target. Despite the malaria control efforts like long-lasting insecticidal nets distribution, rounds of indoor residual spray, the introduction of bi-valent rapid diagnostic tests and artemisinin combination therapy, malaria remained consistent in Dolonibasti sub-center of Orang block primary health center (BPHC) under the district Udalguri, Assam state followed by abrupt rise in cases in 2018. Therefore, we aimed to investigate the factors driving the malaria transmission in the outbreak area of Dolonibasti sub-center. Malaria epidemiological data (2008–2018) of Udalguri district and Orang BPHC was collected. The annual (2011-2018) and monthly (2013–2018) malaria and meteorological data of Dolonibasti sub-center was collected. An entomological survey, Knowledge, Attitude and Practices study among malaria cases (n = 120) from Dolonibasti was conducted. In 2018, 26.1 % (2136/ 8188) of the population of Dolonibasti were found to be malaria positive, of which 55% were adults (n = 1176). Majority of cases were from tea tribe populations (90%), either asymptomatic or with fever only, 67.5 % (81/120) had experienced malaria infection during past years. The outbreak was characterized by a strong increase in cases in June 2018, high proportion of slide falciparum rate of 26.1% (other years average, 15.8%) and high proportion of P. falciparum of 81.2 % (other years average, 84.3%). Anopheles minimus s.l. was the major vector with 28.6% positivity and high larval density in paddy fields/ drainage area. Annual relative humidity was associated with rise in malaria cases, annual parasite incidence (r_s = 0.69, 90%CI; p = 0.06) and slide positivity rate (r_s = 0.83, 95%CI; p = 0.01). Older people were less educated (r_s = −0.66; p < 0.001), had lesser knowledge about malaria cause (r_s = −0.42; χ²=21.80; p < 0.001) and prevention (r_s = −0.18; p = 0.04). Malaria control practices were followed by those having knowledge about cause of malaria (r_s = 0.36; χ² = 13.50; p < 0.001) and prevention (r_s = 0.40; χ² = 17.71; p < 0.001). Altogether, 84.6% (44/52) of the respondents did not use protective measures. We described a sudden increase in malaria incidence in a rural, predominantly tea tribe population group with high illiteracy rate and ignorance on protective measures against malaria. More efforts that are concerted needed to educate the community about malaria control practices.

Genetic polymorphism of Plasmodium falciparum msp-1, msp-2 and glurp vaccine candidate genes in pre-artemisinin era clinical isolates from Lakhimpur district in Assam, Northeast India

Background

Northeast India shares its international border with Southeast Asia and has a number of malaria endemic zones. Monitoring genetic diversity of malaria parasites is important in this area as drug resistance and increasing genetic diversity form a vicious cycle in which one favours the development of the other. This retrospective study was done to evaluate the genetic diversity patterns in Plasmodium falciparum strains circulating in North Lakhimpur area of Assam in the pre-artemisinin era and compare the findings with current diversity patterns.

Methods

Genomic DNA extraction was done from archived blood spot samples collected in 2006 from malaria-positive cases in Lakhimpur district of Assam, Northeast India. Three antigenic markers of genetic diversity were studied – msp-1 (block-2), msp-2 (block-3) and the glurp RII region of P. falciparum using nested PCR.

Results

Allelic diversity was examined in 71 isolates and high polymorphism was observed. In msp-1, eight genotypes were detected; K1 (single allele), MAD20 (six different alleles) and RO33 (single allele) allelic families were noted. Among msp-2 genotypes, 22 distinct alleles were observed out of which FC27 had six alleles and IC/3D7 had 16 alleles. In RII region of glurp, nine genotypes were obtained. Expected heterozygosity (H_E) values of the three antigenic markers were 0.72, 0.81 and 0.88, respectively. Multiplicity of infection (MOI) values noted were 1.28, 1.84 and 1.04 for msp-1, msp-2 and glurp, respectively.

Conclusion

Results suggest a high level of genetic diversity in P. falciparum msp (block-2 of msp-1 and block-3 of msp-2) and the glurp RII region in Northeast India in the pre-artemisinin era when chloroqunine was the primary drug used for uncomplicated falciparum malaria. Comparison with current studies have revealed that the genetic diversity in these genes is still high in this region, complicating malaria vaccine research.

Social and housing indicators of dengue and chikungunya in Indian adults aged 45 and above: Analysis of a nationally representative survey (2017-18)

Background

Dengue and chikungunya (CHIKV) are the two major vector-borne diseases of serious public health concern in India. Studies on socioeconomic and housing determinants of dengue and CHIKV at a pan-India level are lacking. Here, we took advantage of the recently carried out Longitudinal Ageing Study in India (LASI) carried out across all the states and Union Territories of India to study the social indicators of dengue and CHIKV in India.

Methods

LASI-1 (2017-2018) data on the self-reported period prevalence of dengue and CHIKV from 70,932 respondents aged ≥45 years were used for this analysis. The state-wise distribution of dengue and CHIKV was mapped. Prevalence was estimated for each study variable, and the difference was compared using the χ2 test. The adjusted odds ratios (AOR) of the socioeconomic and housing variables for dengue and CHIKV were estimated using the multiple logistic regression model.

Results

Urban residence is the major socio-economic indicator of dengue and CHIKV (dengue AOR: 1.57, 95% CI: 1.18-2.11; CHIKV AOR: 1.84, 95% CI: 1.36-2.49). The other notable indicator is wealth; rich respondents have higher odds of dengue and CHIKV. Adults older than 54 years and those with high school education and above are associated with a lower likelihood of dengue and CHIKV. In addition, CHIKV is associated with scheduled and forward castes, households with improper toilet facilities, open defecation, and kutcha house type.

Conclusions

Despite the limitation that the data is only from adults ≥ 45, this analysis provides important insights into the socioeconomic and housing variables associated with higher odds of dengue and CHIKV in India. Understanding these determinants may assist in the national planning of prevention and control strategies for dengue and CHIKV.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13690-022-00868-5.

India Needs to Consider Planning a Change to Artemether-Lumefantrine to Treat Plasmodium falciparum Malaria

As the malaria elimination target draws closer for India, it must be ensured that the country's policies, strategies, and tools remain effective. Artemisinin-based combination therapies are the mainstay of Plasmodium falciparum malaria management. India has a differential standard therapy for uncomplicated falciparum malaria in the form of artemether-lumefantrine in its northeastern states and artesunate + sulfadoxine-pyrimethamine in the rest of the country. The clinical failure of artesunate + sulfadoxine-pyrimethamine in the northeast regions were attributed primarily to parasite resistance resulting from mutations in the enzymes dihydropteroate synthase and dihydrofolate reductase. Artemether-lumefantrine was therefore substituted for artesunate + sulfadoxine-pyrimethamine in the region. The change has been a success, as evidenced by the therapeutic efficacy studies conducted at regular intervals in India. However, studies suggest that resistance may be emerging toward sulfadoxine-pyrimethamine in multiple parts of the nation. Hence, there is a possibility that the artesunate + sulfadoxine-pyrimethamine combination may be acting in part as a monotherapy, and this makes the longevity of the artesunate + sulfadoxine-pyrimethamine drug combination therapy uncertain. The increasing presence of drug-resistant mutants in P. falciparum dhps and dhfr genes suggests the need for a policy switch for uncomplicated P. falciparum malaria from artesunate + sulfadoxine-pyrimethamine to artemether-lumefantrine.

Genetic diversity of Plasmodium falciparum AMA-1 antigen from the Northeast Indian state of Tripura and comparison with global sequences: implications for vaccine development

Background

Malaria continues to be a major public health problem in the Northeastern part of India despite the implementation of vector control measures and changes in drug policies. To develop successful vaccines against malaria, it is important to assess the diversity of vaccine candidate antigens in field isolates. This study was done to assess the diversity of Plasmodium falciparum AMA-1 vaccine candidate antigen in a malaria-endemic region of Tripura in Northeast India and compare it with previously reported global isolates with a view to assess the feasibility of developing a universal vaccine based on this antigen.

Methods

Patients with fever and malaria-like illness were screened for malaria and P. falciparum positive cases were recruited for the current study. The diversity of PfAMA-1 vaccine candidate antigen was evaluated by nested PCR and RFLP. A selected number of samples were sequenced using the Sanger technique.

Results

Among 56 P. falciparum positive isolates, Pfama-1 was successfully amplified in 75% (n = 42) isolates. Allele frequencies of PfAMA-1 antigen were 16.6% (n = 7) for 3D7 allele and 33.3% (n = 14) in both K1 and HB3 alleles. DNA sequencing revealed 13 haplotypes in the Pfama-1 gene including three unique haplotypes not reported earlier. No unique amino-acid substitutions were found. Global analysis with 2761 sequences revealed 435 haplotypes with a very complex network composition and few clusters. Nucleotide diversity for Tripura (0.02582 ± 0.00160) showed concordance with South-East Asian isolates while recombination parameter (Rm = 8) was lower than previous reports from India. Population genetic structure showed moderate differentiation.

Conclusions

Besides documenting all previously reported allelic forms of the vaccine candidate PfAMA-1 antigen of P. falciparum, new haplotypes not reported earlier, were found in Tripura. Neutrality tests indicate that the Pfama-1 population in Tripura is under balancing selection. This is consistent with global patterns. However, the high haplotype diversity observed in the global Pfama-1 network analysis indicates that designing a universal vaccine based on this antigen may be difficult. This information adds to the existing database of genetic diversity of field isolates of P. falciparum and may be helpful in the development of more effective vaccines against the parasite.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-022-04081-1.

Malaria Epidemiology Along the Indian Districts Bordering Bhutan and Implications for Malaria Elimination in the Region

It is important for malaria-endemic countries to address malaria control across international borders, and in particular to prioritize appropriate rapid diagnosis, treatment and surveillance. Bhutan and India aim to achieve malaria elimination by 2023 and 2030 respectively. Malaria elimination along the Indo-Bhutan border is of common concern. We delineated malaria epidemiology along the border to provide a blueprint for focusing malaria control efforts in key foci within this region. Epidemiological data from 2015 to 2019 were analyzed, as the most drastic reductions in malaria burden across most parts of India were witnessed in this time frame. Several areas of concern include low surveillance in most border districts, favorable climatic conditions for perennial malaria transmission, and movement of potential parasite carriers because of the porous borders. India and Bhutan need to control the importation/exportation of malaria cases. We highlight the foci of concern for which implementing tailor-made malaria control strategies may benefit both countries.

Study of epidemiological behaviour of malaria and its control in the Purulia district of West Bengal, India (2016-2020)

Purulia is a malaria-prone district in West Bengal, India, with approximately half of the blocks defined as malaria endemic. We analyzed the malaria case in each block of the Purulia district from January 1, 2016, to December 31, 2020. As per the API, 20 blocks of Purulia were assigned to four different categories (0–3) and mapped using ArcGIS software. An exponential decay model was fitted to forecast the trend of malaria cases for each block of Purulia (2021–2025). There was a sharp decrease in total malaria cases and API from 2016 to 2020 due to the mass distribution of LLINs. The majority of cases (72.63%) were found in ≥ 15-year age group. Males were more prone to malaria (60.09%). Malaria was highly prevalent among Scheduled Tribes (48.44%). Six blocks were reported in Category 3 (high risk) and none in Category 0 (no risk) in 2016, while no blocks were determined to be in Category 3, and three blocks were in Category 0 in 2020. The exponential decay model prediction is oriented towards gaining malaria-free status in thirteen blocks of Purulia by 2025. This study will incite the government to uphold and strengthen the current efforts to meet the malaria elimination goals.

Household and individual level risk factors associated with declining malaria incidence in Meghalaya, India: implications for malaria elimination in low-endemic settings

Background

A detailed analysis of household and individual level Plasmodium infection patterns in two low-endemic districts of Meghalaya was undertaken to better understand the epidemiology of malaria in northeast India.

Methods

Socio-demographic and behavioural information from residents (aged 1–69 years) of households were collected through pre-tested, questionnaire conducted in 2018 and 2019. Blood samples collected from participants were tested for Plasmodium falciparum and/or Plasmodium vivax infection using rapid diagnostic test, microscopy and PCR. Plasma samples from a subset of participants were analysed for antibodies against thirteen P. falciparum and four P. vivax antigens. Associations between household and individual level risk factors, and Plasmodium infections were evaluated using multilevel logistic regression models.

Results

A total of 2753 individuals from 827 households were enrolled in 2018, and 834 individuals from 222 households were enrolled in 2019. Of them, 33 (1.2%) were positive by PCR for P. falciparum in 2018 and none were positive for P. vivax. In 2019, no PCR-positive individuals were detected. All, but one, infections were asymptomatic; all 33 infections were sub-microscopic. Reported history of malaria in the past 12 months (OR = 8.84) and history of travel in the past 14 days (OR = 10.06) were significantly associated with Plasmodium infection. A significant trend of increased seropositivity with age was noted for all 17 antigens. Although adults (≥ 18 years) consistently had the highest seropositivity rates, a sizeable proportion of under-five children were also found to be seropositive. Almost all individuals (99.4%) reported sleeping under an insecticide-treated bed-net, and household indoor residual spray coverage in the 12 months preceding the survey was low (23%). Most participants correctly identified common signs and symptoms of malaria, i.e., fever (96.4%), headache (71.2%), chills (83.2%) and body-ache (61.8%). Almost all participants (94.3%) used government-provided services for treatment of malaria.

Conclusion

This study explored the epidemiology of malaria in two communities in Meghalaya, India, in the context of declining transmission. The presence of widespread asymptomatic infections and seropositivity among under-five children suggest that low-level Plasmodium transmission persists in this region. Implications of the study findings for malaria elimination efforts in low-transmission settings are discussed.

Vector-borne and zoonotic infections and their relationships with regional and socioeconomic statuses: An ID-IRI survey in 24 countries of Europe, Africa and Asia

BACKGROUND

In this cross-sectional, international study, we aimed to analyze vector-borne and zoonotic infections (VBZI), which are significant global threats.

METHOD

VBZIs' data between May 20-28, 2018 was collected. The 24 Participatingcountries were classified as lower-middle, upper-middle, and high-income.

RESULTS

382 patients were included. 175(45.8%) were hospitalized, most commonly in Croatia, Egypt, and Romania(P = 0.001). There was a significant difference between distributions of VBZIs according to geographical regions(P < 0.001). Amebiasis, Ancylostomiasis, Blastocystosis, Cryptosporidiosis, Giardiasis, Toxoplasmosis were significantly more common in the Middle-East while Bartonellosis, Borreliosis, Cat Scratch Disease, Hantavirus syndrome, Rickettsiosis, Campylobacteriosis, Salmonellosis in Central/East/South-East Europe; Brucellosis and Echinococcosis in Central/West Asia; Campylobacteriosis, Chikungunya, Tick-borne encephalitis, Visceral Leishmaniasis, Salmonellosis, Toxoplasmosis in the North-Mediterranean; CCHF, Cutaneous Leishmaniasis, Dengue, Malaria, Taeniasis, Salmonellosis in Indian Subcontinent; Lassa Fever in West Africa. There were significant regional differences for viral hemorrhagic fevers(P < 0.001) and tick-borne infections(P < 0.001), and according to economic status for VBZIs(P < 0.001). The prevalences of VBZIs were significantly higher in lower-middle income countries(P = 0.001). The most similar regions were the Indian Subcontinent and the Middle-East, the Indian Subcontinent and the North-Mediterranean, and the Middle-East and North-Mediterranean regions.

CONCLUSIONS

Regional and socioeconomic heterogeneity still exists for VBZIs. Control and eradication of VBZIs require evidence-based surveillance data, and multidisciplinary efforts.

Defeating malaria in the North-East region: the forerunner for malaria elimination in India

India is a malaria endemic country which is targeting malaria elimination by 2027. Transmission intensities are low-to-moderate depending on the region supported by multiple disease vectors. Among these, comparatively North-East India contributes to high proportions of malaria cases annually, the majority of which are due to Plasmodium falciparum (90%). Anopheles minimus and An. baimaii (sibling species in the An. dirus complex) are widely prevalent and incriminated as vectors of malaria. Number of intervention tools were field-evaluated beginning 1988 to date against disease vectors and causative parasites to contain the spread of malaria. These included (i) insecticide-treated netting materials (ITNs) for vector control, (ii) rapid diagnostic tests (RDTs) for in situ diagnosis, and (iii) therapeutic efficacy of artemisinin-based combination therapies (ACTs) for improved drug-policy; all of which were incorporated in healthcare services resulting in substantial disease transmission reduction. Populations of both An. minimus and An. baimaii were observed depleting, instead An. culicifacies s.l. recorded to be fast invading degraded forests and assessed to be resistant to multiple insecticides. Of the two prevalent Plasmodium species, while P. vivax continued to be susceptible to chloroquine therapy, P. falciparum had emerged resistant to most available antimalarial drugs except ACTs over space and time and spreading to peninsular India threatening elimination efforts. Disease transmission trends were observed to be declining for which the state of Assam has made huge strides reporting steady fall in cases each passing year vis-à-vis Meghalaya, Mizoram and Tripura (all sharing international border with Bangladesh), in which malaria transmission remained uninterrupted. Consequently, control of malaria in the North-East region of India is of immediate importance and needs prioritization for intensified disease surveillance and control interventions coupled with improved access to healthcare services mitigating risk of disease outbreaks and spread of drug-resistant malaria helping realize the goal of malaria elimination in the country.

Socio-economic and household determinants of malaria in adults aged 45 and above: analysis of longitudinal ageing survey in India, 2017-2018

Background

Even though malaria cases have drastically come down in the last decade, malaria remains a serious public health concern in many parts of India. National Framework for Malaria Elimination in India (2016–2030) has been launched with the goal to eliminate malaria by 2030. Understanding the socio-economic and household determinants of malaria at the national level will greatly aid India’s malaria elimination efforts.

Methods

The data from Longitudinal Ageing Survey of India (LASI) Wave 1 (2017–2018) survey comprising 70,671 respondents ≥ 45 years across all the States and Union Territories were used for the analysis. Simple and multiple logistic regressions were used to obtain the unadjusted and adjusted odds ratio respectively of the socio-economic and household variables.

Results

The major socio-economic variables that increase the likelihood of malaria are caste (‘scheduled tribes’), low education levels and rural residence. The scheduled tribes have 1.8 times higher odds of malaria than the scheduled castes (AOR: 1.8; 95% CI: 1.5–2.1). Respondents with high school education (6–12 grade) (AOR: 0.7; 95% CI: 0.6–0.8) and college education (AOR: 0.5; 95% CI: 0.4–0.6) had a very low risk of malaria than those with no school years. Rural residence and occupation (agriculture and allied jobs) also increases the odds of malaria. The major housing determinants are household size (≥ 6), housing type (kutcha), use of unclean fuel, outside water source, improper sanitation (toilet facilities) and damp wall/ceiling.

Conclusions

The study has identified the major socio-economic and housing factors associated with malaria in adults aged 45 and above. In addition to vector and parasite control strategies in the tribal dominated regions of India, improving literacy and housing conditions may help India’s malaria elimination efforts.

Epidemiology and clinical outcomes of severe Plasmodium vivax malaria in India

OBJECTIVES

A systematic review and meta-analysis (SR-MA) of the available Indian literature on severe vivax malaria (SVM) was undertaken.

METHODS

Relevant studies in eight electronic databases were retrieved and reviewed. The preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were followed. The methodological quality of the studies included in the MA was assessed.

RESULTS

Overall, 162 studies were included in the work. The pooled proportion of SVM was 29.3%. The main severity signs/symptoms seen in SVM were jaundice, severe thrombocytopenia (ST), multi-organ dysfunction, and severe anaemia with pooled proportion of 37.4%, 37.2%, 24.2% and 20.4%, respectively. P. falciparum was inducing 6% less ST (RR = 0.94, 95% CI 0.5-1.5, I² = 77.87%), 10% less thrombocytopenia (RR = 0.9, 95% CI 0.7-1.1, I² = 91.68%) and 20% less DIC (RR = 0.8, 95% CI 0.3-1.9, I² = 0%) than P. vivax. An atypical condition like myocarditis, was most commonly observed among the studied SVM cases. The mortality rate in SVM cases ranged from 0 to 12.9% among hospital patients with P. vivax mono-infections.

CONCLUSIONS

The present SR-MA provides evidence for P. vivax as the etiologic agent of severe malaria leading to deaths in few cases as seen recently in India. However, research gaps outlined here emphasise the need for further studies on SVM in pregnancy, SVM in drug resistance and correlations with cytoadherence in disease severity due to P. vivax.

Spatial and temporal village-level prevalence of Plasmodium infection and associated risk factors in two districts of Meghalaya, India

BACKGROUND

Despite declining incidence over the past decade, malaria remains an important health burden in India. This study aimed to assess the village-level temporal patterns of Plasmodium infection in two districts of the north-eastern state of Meghalaya and evaluate risk factors that might explain these patterns.

METHODS

Primary Health Centre passive malaria case data from 2014 to 2018 were analysed to characterize village-specific annual incidence and temporal trends. Active malaria case detection was undertaken in 2018 and 2019 to detect Plasmodium infections using PCR. A questionnaire collected socio-demographic, environmental, and behavioural data, and households were spatially mapped via GPS. Adult mosquitoes were sampled at a subset of subjects' houses, and Anopheles were identified by PCR and sequencing. Risk factors for Plasmodium infection were evaluated using bivariate and multivariate logistic regression analysis, and spatial cluster analysis was undertaken.

RESULTS

The annual malaria incidence from PHC-based passive surveillance datasets in 2014-2018 was heterogenous but declining across villages in both districts. Active surveillance in 2018 enrolled 1468 individuals from 468 households (West Jaintia Hills) and 1274 individuals from 359 households (West Khasi Hills). Plasmodium falciparum prevalence per 100 people varied from 0 to 4.1% in the nine villages of West Jaintia Hills, and from 0 to 10.6% in the 12 villages of West Khasi Hills. Significant clustering of P. falciparum infections [observed = 11, expected = 2.15, Relative Risk (RR) = 12.65; p < 0.001] was observed in West Khasi Hills. A total of 13 Anopheles species were found at 53 houses in five villages, with Anopheles jeyporiensis being the most abundant. Risk of infection increased with presence of mosquitoes and electricity in the households [Odds Ratio (OR) = 1.19 and 1.11], respectively. Households with reported animals had reduced infection risk (OR = 0.91).

CONCLUSION

Malaria incidence during 2014-2018 declined in all study villages covered by the passive surveillance data, a period that includes the first widespread insecticide-treated net campaign. The survey data from 2018 revealed a significant association between Plasmodium infection and certain household characteristics. Since species of Plasmodium-competent mosquito vectors continue to be abundant, malaria resurgence remains a threat, and control efforts should continue.

Study of Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency and Genotype Polymorphism of G6PD B and G6PD (A+/A-) in Patients Treated for Plasmodium vivax Malaria in a Tertiary Care Hospital in North East India

Introduction

Glucose-6-phosphate dehydrogenase (G6PD) enzyme deficiency is the most common enzymopathy in humans, and its distribution has been historically described to be closely associated with that of malaria. North East India provides optimal conditions for transmission of malaria and bears a considerable burden of Plasmodium vivax (P. vivax) malaria. Primaquine, a mainstay in the treatment of vivax malaria, may trigger episodes of acute hemolysis in patients with G6PD deficiency. The present study sought to delineate the frequency and genotypes of G6PD deficiency among patients suffering from vivax malaria infections. 

Methods

Blood specimens from 80 individuals diagnosed with vivax malaria underwent enzyme assay for G6PD deficiency. Samples with deficient phenotype underwent isolation of DNA using a genomic DNA isolation kit (Qiagen India Pvt. Ltd., New Delhi, India). The genomic DNA underwent amplification, serial denaturation, annealing, extension, final extension followed by digestion with restriction endonucleases Nla III and Fok I. The digested products were subjected to horizontal agarose electrophoresis for the separation of digested fragments. Samples without nucleotide 376 adenine→guanine (A→G) mutation were classified as G6PD B. Those with the mutation were further classified into G6PD A(+) and G6PD A(-) based on the presence of Nla III site.

Results

Twenty-seven out of 80 individuals (33.75%) with P. vivax malaria were found to have G6PD deficiency, of which a majority (n=24) had G6PD B genotype. Three individuals had Asparagine→Aspartic Acid mutation at position 376 (A→G), of which G6PD A(+) and G6PD A(-) were present in two and one cases, respectively.

Conclusion

G6PD deficiency was noted in about a third of patients with vivax malaria. Since primaquine therapy is contraindicated in this group of patients, there is a rationale for looking into screening patients with vivax malaria from the region prior to primaquine therapy. Further large scale studies may substantiate this and help in better genotypic and geographic characterization of G6PD deficiency in the region.