Nation-wide vector surveillance on Zika and Dengue did not indicate transmission of the American lineage-pandemic Zika virus in India

OBJECTIVES

Following the Public Health Emergency of International Concern declared on Zika by the World Health Organization during 2016, the Indian Council of Medical Research carried out nationwide vector surveillance for Zika and Dengue viruses (ZIKV and DENV) in India as a preparedness measure in 2016-19.

METHODS

High-risk zones distributed to 49 Districts in 14 states/union territories were included in the study. Seven ICMR institutions participated, following a standard operating protocol. Aedes specimens sampled weekly were processed by multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) for ZIKV/DENV and random samples crosschecked with real-time RT-PCR for ZIKV.

RESULTS

Altogether, 79 492 Aedes specimens in 6492 pools were processed; 3 (0.05%) and 63 (0.97%) pools, respectively, were found positive for ZIKV and DENV. ZIKV infections were recorded in Aedes aegypti sampled during the 2018 sporadic Zika outbreak in Jaipur, Rajasthan. However, these belonged to the Asian lineage of the virus, already circulating in the country. Both Ae. aegypti and Aedes albopictus distributed to 8 states/union territories were found to be infected with DENV. Both sexes of Ae. albopictus were infected, indicating transovarial transmission.

CONCLUSION

This investigation evinced no active transmission of the American lineage-pandemic Zika virus in India during the pandemic period.

Predatory potential of Platynectes sp. (Coleoptera: Dytiscidae) on Aedes albopictus, the vector of dengue/chikungunya in Kerala, India

Unused and discarded latex collection containers (LCCs) are the major breeding habitats of Aedes albopictus in the rubber plantations of Kerala, India. Platynectes sp. (Family: Dytiscidae) was observed to invade these habitats during the monsoon season and voraciously devour the larval instars of this major vector species of arbo-viral diseases. Field observations showed a reduction of 70.91% (p = 0.0017) and 100% in Aedes larval density, on the first and four days post release of eight beetles per LCC respectively. In laboratory, a beetle was found to devour 17.75 + 5.0 late larval instars of Ae. albopictus per day. Our findings indicate Platynectes sp. could be a potential bio-control agent against Ae. albopictus, the vector of chikungunya/dengue fevers, in rubber plantations.

Coffee husk waste for fermentation production of mosquitocidal bacteria

Coffee husk waste (CHW) discarded as bio-organic waste, from coffee industries, is rich in carbohydrates. The current study emphasizes the management of solid waste from agro-industrial residues for the production of biopesticides (Bacillus sphaericus, and B. thuringiensis subsp. israelensis), to control disease transmitting mosquito vectors. An experimental culture medium was prepared by extracting the filtrates from coffee husk. A conventional culture medium (NYSM) also was prepared. The studies revealed that the quantity of mosquitocidal toxins produced from CHW is at par with NYSM. The bacteria produced in these media, were bioassayed against mosquito vectors (Culex quinquefasciatus, Anopheles stephensi, and Aedes aegypti) and it was found that the toxic effect was statistically comparable. Cost-effective analysis have revealed that, production of biopesticides from CHW is highly economical. Therefore, the utilization of CHW provides dual benefits of effective utilization of environmental waste and efficient production of mosquitocidal toxins.

A medium for the production of biopesticides (Bacillus sphaericus and Bacillus thuringiensis subsp. israelensis) in mosquito control

Chicken feathers, discarded as bioorganic wastes from poultry processing industries, are rich in keratin (structural protein). Deoiled rice bran (DRB), in contrast, is an agrowaste product consisting of protein, fiber, and carbohydrates. This study highlights a new medium for producing biopesticides from these bioorganic wastes, by culturing Bacillus sphaericus (Bs) and B. thuringiensis subsp. israelensis (Bti), to synthesize mosquitocidal toxins. Biochemical studies indicated that the amount of mosquitocidal spore/crystal toxins produced from the experimental culture medium (chicken feather waste [CFW] + DRB) is higher than that from the conventional medium (Nutrient Yeast Extract Salt Medium [NYSM]). The bacteria produced in these media (NYSM, CFW, DRB, and CFW + DRB) were bioassayed against mosquito vectors, and the toxic effect was found to be statistically similar (fiducial limits overlapping). Cost analysis based on the raw materials, indicated that, the use of CFW and DRB, as culture medium, is highly economical, for the industrial production of these mosquito pathogenic bacilli.