In target areas where human mosquito-borne diseases are diagnosed, the inclusion of the pre-adult mosquito aquatic niches parameters will improve the integrated mosquito control program

Assessment of Epidemiological Indicators for Evaluation of National Malaria Elimination Programme: A Retrospective Study

Background

Malaria has been one of India's most considerable health problems since 1940. The objective of our study is to determine the status of the National Malaria Elimination Programme in India by using epidemiological indicators.

Methods and Materials

The annual reports of malaria for the years 2014-2021 and monthly reports for 2020 and 2021 were collected from the official web portal and were analysed for study specific assessments.

Results

The API has shown a statistically significant reduction from 2017-2021 in all states along with category-1(P=0.003) and category-2(P=0.029) states/UTs, but there was no statistically significant reduction from 2017-2021 in category-3 (P=0.166) states/UTs. The zero indigenous cases had not been achieved in category-1 states/UTs. The overall percentage reduction in number of malaria cases in 2020 at the national level compared with 2014 was 83.6%. Despite states with strong health systems such as Gujarat, Maharashtra and Karnataka, have not shown zero indigenous cases in 2020 and the malaria cases noted were very far from reaching the targets.

Conclusions

Although we observed a significant drop in malaria incidence from 2014 to 2020, demonstrating that the country is moving nearer to malaria elimination, it is crucial to implement the strategies to reduce Plasmodium falciparum% and re-establish surveillance programmes and execute national and state programmes in order to achieve the success of the National Malaria Elimination Programme. The recategorization of states/UTs are in accordance to the API, and implementation strategies were also needed.

Combined effect of physico-chemical and microbial quality of breeding habitat water on oviposition of malarial vector Anopheles subpictus

Mosquitoes prefer diverse water bodies for egg laying and larval survival. Present study was performed with an objective to characterize physico-chemical properties and microbial profiling of breeding habitat water bodies of Anopheles subpictus mosquitoes. A field survey was accomplished to check the presence of An. subpictus larvae to record per dip larval density in various breeding habitats throughout the year. Physico-chemical and bacteriological properties in relation to mosquito oviposition were assessed. Dissolved oxygen content, pH and alkalinity were found to have major impacts and ponderosity on the prevalence of An. subpictus larvae. Larval density showed significant positive correlation with dissolved oxygen content of water and significant negative correlation with pH and alkalinity of habitat water. Comparatively higher population (cfu/mL) of Bacillus spp. competent with starch hydrolyzing and nitrate reducing properties were recorded all the breeding habitat water bodies of An. subpictus. Higher amplitude of anopheline larvae was portrayed during monsoon and post-monsoon season in clear water with an inclining trend to high dissolved oxygen content and neutral pH. B. cereus, B. megaterium, B. subtilis and B. tequilensis prevalent in all habitat water bodies were marked as oviposition attractants of gravid An. subpictus mosquitoes. Microbial population played key roles in the modulation of physico-chemical parameters of habitat water with a view to enhance its acceptability by gravid mosquitoes in relation to their oviposition. Better understanding of the interactions along with the control of oviposition attractant bacterial strains from mosquito breeding habitats might contribute to the vector management programme.

An insight of anopheline larvicidal mechanism of Trichoderma asperellum (TaspSKGN2)

Anopheline larvicidal property of T. asperellum has been found recently in medical science. The mechanism of actions exhibited by T. asperellum to infect mosquito larvae is the pivotal context of our present study. To infect an insect, entomopathogens must undergo some events of pathogenesis. We performed some experiments to find out the mechanisms of action of T. asperellum against anopheline larvae and compared its actions with other two well recognized entomopathogens like Metarhizium anisopliae and Beauveria bassiana. The methodology adopted for this includes Compound light and SE Microscopic study of host-pathogen interaction, detection of fungal spore adhesion on larval surface (Mucilage assay), detection of cuticle degrading enzymes (Spore bound pr1, chitinase and protease) by spectro-photometric method, Quantitative estimation of chitinase and protease enzymes, and determination of nuclear degeneration of hemocyte cells of ME (methanolic extract) treated larvae by T. asperellum under fluorescence microscope. Compound light microscopic studies showed spore attachment, appressorium and germ tube formation, invasion and proliferated hyphal growth of T. asperellum on epicuticle and inside of dead larvae. SEM study also supported them. After 3 h of interaction, spores were found to be attached on larval surface exhibiting pink colored outer layer at the site of attachment indicating the presence of mucilage surrounding the attached spores. The enzymatic cleavage of the 4-nitroanilide substrate yields 4-nitroaniline which indicates the presence of spore-bound PR1 protein (Pathogenecity Related 1 Protein) and it was highest (absorbance 1.298 ± 0.002) for T. asperellum in comparison with control and other two entomopathogens. T. asperellum exhibited highest enzymatic index values for both chitinase (5.20) and protease (2.77) among three entomopathogens. Quantitative experiment showed that chitinase enzyme concentration of T. asperellum (245 µg mL^-1) was better than other two M. anisopliae (134.59 µg mL^-1) and B. bassiana (128.65 µg mL^-1). Similarly protease enzyme concentration of this fungus was best (298.652 µg mL^-1) among three entomopathogens. Here we have detected and estimated fragmentized nuclei of hemocyte cells by fluorescence microscopy in treated larvae with different ME doses of T. asperellum, and also observed that mosquito larvae exposed to 0.1 mg mL^-1 dose of ME showed maximum (100%) nuclear fragmentations of hemocytes and while 20, 45, 70 and 85% of nuclear deformities were recorded at 0.02, 0.04, 0.06 and 0.08 mg mL^-1 concentrations of ME. The knowledge of this work certainly will help in understanding of mechanism of action of T. asperellum for anopheline larval killing and consequently in eradication of malaria vector.