Controlling Mosquito-borne diseases

Controlling Mosquito-borne diseases

Subject: Science and Tech

Context: Mosquito-borne diseases have been a scourge for thousands of years, with huge armies defeated, and economies shattered. The reports announcing an effective malaria vaccine, following clinical trials in Burkina Faso conducted by the University of Oxford, the Serum Institute of India and others.

Content:

Malaria vaccine

• Malaria, the parasites spread through the bites of infected female Anopheles mosquitoes.Four types of malaria parasites can infect humans: Plasmodium Vivax, P. ovale, P. malariae and P. falciparum. Plasmodium falciparum and Plasmodium Vivax are the most common types that infect humans.Plasmodium falciparum causes a more severe form of the disease leading to higher risk of death.
• The R21 vaccine targets the ‘circumsporozite’ protein (CSP) of the malarial parasite, Plasmodium falciparum. The sporozite stage of this parasite secretes CSP. Mosquito bites transfer the CSP and sporozites into the human bloodstream, and the CSP nudges the parasite towards the liver, where it enters liver cells, matures and proliferates. The release of mature merozites marks the onset of the symptoms of malaria. Efficient vaccines
• The WHO has cleared another vaccine, called

Dengue vaccine

• Dengue is a mosquito-borne tropical disease caused by the dengue virus (Genus Flavivirus), transmitted by several species of mosquito within the genus Aedes, principally Aedes aegypti. This mosquito also transmits chikungunya, yellow fever and Zika infection. There are 4 distinct, but closely related, serotypes (separate groups within a species of microorganisms that all share a similar characteristic) of the virus that cause dengue (DEN-1, DEN-2, DEN-3 and DEN-4). Serotypes make vaccine development difficult, as a different vaccine is needed against each serotype.
• DENGVAXIA, from Sanofi Pasteur, is approved in several countries and shows efficacies ranging from 42% to 78% against the four serotypes of the virus
• In India, ZydusCadilla has been developing a DNA Vaccine against dengue.

Bacterium Wolbachia pipientis :

• An interesting strategy involves a bacterium, Wolbachia pipientis, an intracellular parasite commonly found in many insects, but not in the dengue-carrying mosquito. When introduced into this mosquito’s cells, this parasite competes successfully against other parasites such as the viruses that cause dengue, chikungunya, yellow fever and Zika.
• Aedes mosquitoes, doped with Wolbachia in the laboratory, are released in localities where the disease is prevalent. They quickly spread the bacterium to native Aedes mosquitoes, and the incidence of new dengue cases starts to decline.

Other ways

• Both mosquitoes and the Plasmodium parasite need warm, moist weather to flourish. Using data continuously gathered by environmental satellites such as the NOAA-19, scientists at ICMR’s National Institute of Malaria Research have built elaborate models that correlate monthly rainfall data and data on annual state-wise incidence of dengue and malaria with the El-Nino Southern Oscillation, which influences global atmospheric circulation.