About Time We Took The Bite Out Of Our Malaria Epidemic | Mint - Mint
As the covid pandemic slowly fades into endemic existence, it will do so as a catastrophe that impacted nearly 10% of humanity with a fatality rate of over 1%. A median country in the top 25 had a fatality rate of about 2,500 per million population and the Sars-CoV-2 virus caused unprecedented disruption to daily life.
While only an episodic pandemic has that destructive an effect on humanity, vector-borne diseases make up a very large part of the illness burden that impacts us each year. Vector-borne diseases are human illnesses caused by parasites, viruses and bacteria that are transmitted by vectors. Vectors, in turn, can be mosquitoes, ticks and fleas that spread pathogens. Common vector-borne diseases across the world include malaria, dengue, yellow fever, chikungunya, Japanese encephalitis (JE) and Zika. These diseases account for about 17% of the estimated global burden of all infectious diseases and cause around 700,000 deaths a year. It is a tragic fact that each decade, vector-borne diseases cause the same number of deaths as the pandemic has done in these past two years. To make it worse, vector-borne diseases disproportionately impact children below five years of age.
Worldwide, malaria has had the most devastating impact. This is a life-threatening disease caused by the Plasmodium parasite and is transmitted through the bite of an infected female Anopheles mosquito. According to the World Health Organization (WHO), there were an estimated 241 million cases of malaria worldwide in 2020. Africa had the burden of nearly 95% of these cases. India reported nearly 400,000 cases each year before the pandemic began, but the numbers have come down significantly since then. The disease is concentrated in Nigeria, the Democratic Republic of Congo, Tanzania and Mozambique. Nearly 625,000 people died in 2020, most of them children. Malaria is preventable and curable, even though there has not been an effective or approved vaccine until very recently.
Malaria prevention techniques have largely focused on 'vector control'. The idea is to control mosquitoes from breeding in human settlements and to prevent mosquito bites. Insecticide-treated bed nets have been effective in reducing the burden of malaria, as has the spraying of breeding sites. But progress in malaria mitigation is being threatened by emerging resistance to insecticides among Anopheles mosquitoes.
Malaria treatment has been effective through artemisinin combination therapies (ACT). Artemisinin is a semi-synthetic drug inspired by an extract from the plant Artemisia, a sweet wormwood well known in traditional Chinese medicine (TCM). It was discovered by the Nobel laureate Chinese researcher Tu Youyou in response to a call to use TCM in solving the problem of rampant malaria among Chinese troops in Vietnam. Here too, some drug resistance has been observed.
In 2021, for the very first time, the WHO approved a malaria vaccine called RTS,S for children. While the vaccine took decades to develop, it appears that this multi-shot vaccine is about 50% effective and will gradually be rolled out around the world. A vaccine with 77% efficacy in Phase 2 trials, in the form of R21/Martix-M from the University of Oxford, should soon become available. Oxford has a partnership with Serum Institute of India for the large-scale, low-cost manufacture of the vaccine. BioNTech, the firm that came up with the mRNA vaccine for covid marketed by Pfizer, is working on developing one for malaria. Malaria vaccines have proven elusive for a reason. Ugur Sahin, chief executive officer of BioNTech, says "Our goal is to make the parasite visible and detectable from the very beginning when it is the most vulnerable."
Beyond vaccines and drugs, there is an attempt to genetically modify the Anopheles population by increasing the number of males and by restricting the females from reproducing. While pilot experiments have been successful, the environmental permissions and ethical questions that this raises will take many years to sort out.
India has been successful in gradually reducing malaria cases and significantly reducing malarial fatalities. But the dramatic reduction during the pandemic is likely on account of under-reporting. The National Framework for Malaria Elimination aims to eradicate the disease in the country by 2030. As malaria mitigation stalls in other parts of the world, India will need to consolidate its gains before insecticide and drug resistance threatens that progress.
India is also home to dengue, chikungunya and JE. All these diseases are carried by different type of mosquitoes. JE has a very effective and well-tested vaccine that will need to be more systematically administered in endemic regions like eastern Uttar Pradesh, West Bengal and Bihar. The only approved dengue vaccine has severe limitations, unfortunately, while there is no vaccine yet for chikungunya.
With the new-found scientific vitality brought about by covid and the start of our annual 'vector-borne season', it will be to India's advantage to focus on the prevention, mitigation and eventual elimination of these diseases. A combination of new and old science, systematically applied, promises to deliver India from these scourges.
P.S: "You cannot rush the science, but when the science points you in the right direction, then you can start rushing," said Anthony Fauci, America's top official for infectious diseases.
Narayan Ramachandran is chairman, InKlude Labs. Read Narayan's Mint columns at www.livemint.com/avisiblehand
Comments
Post a Comment