Mutating parasite may foil India’s plans to be malaria free by 2030
India’s target is to be ‘malaria free’ by 2030, but the parasite’s formidable adaptability has helped it evade every frontline drug, making the countdown to elimination far from easy.india Updated: Apr 24, 2016 18:27 IST
Manik Baruah, 37, has lost count of the number of times he was sickened with malaria when he was growing up in Guwahati. Last year, however, the malaria infection that struck him in Delhi almost killed him. Baruah was infected with chloroquine-resistant drug-resistant P. falciparum parasite, which was causing disease only in the north-eastern states a decade ago. The resistant strain has higher rates of complications and causes 90% of malarial deaths.
This deadly strain has now replaced the milder P. vivax malaria across India and now accounts for 66% of all malaria cases.“Five years ago, most people hospitalised with P. falciparum in Delhi were those who were either from endemic areas in the east and north-eastern states of India or had recently travelled there. Now it is striking people who have not stepped out of Delhi, which suggests localised transmission,” says Dr Anupam Sibal, group medical director, Apollo Hospitals.
Recorded malaria cases in India almost halved from 2.03 million in 2001 to 1.13 million in 2015, and confirmed deaths fell from 1,005 in 2001 to 287 people in 2015. This prompted India to launch the National Framework for Malaria Eradication in February with a target to be certified “malaria free” in 2030 by the World Health Organisation. The goal is to reduce the occurrence to 1 in every 1,000 across India, and stop transmission altogether by 2027.
The plan looks great on paper but the parasite’s rising resistance to drugs and the Anopheles mosquito’s resistance to insecticides threaten to make the countdown to elimination far from easy.
In India, 80% of malaria cases occur among 20% of its population living in the 200 high-risk districts of Andhra Pradesh, Chhattisgarh, Gujarat, Jharkhand, Karnataka, Madhya Pradesh, Maharashtra, Odisha, West Bengal and the seven northeastern states. With fewer than half of those infected reaching a clinic or hospital, infection deaths and cases are a lot higher than recorded. Frequent infections cause chronic malnutrition, anaemia, abortions and low birthweight babies, which raise the socio-economic burden of malaria to more than `11,000 crore ($1.94 billion), estimates the World Health Organisation.
The Anopheles mosquito, which bites between dusk and dawn, spreads the infection caused by single-celled Plasmodium parasites, with P. falciparum and P. vivax between them causing most infections in India. The An. culicifacies is the principal vector of rural malaria and accounts for 60-70% of annual cases, while the An. stephensi is dominant in urban areas. Irrespective of the type of mosquito spreading infection, the disease remains the same.
The parasite causes infection between persons through mosquito bites, which it uses to invade the liver and then the red blood cells. At first, the symptoms are generic — fever, headache, sweats, chills and vomiting — and at this stage, the immune system usually manages to control the infection. In severe malaria, the parasite disrupts blood supply to the vital organs, including the brain, causing seizures and death.
Scientists acknowledge that the parasite is a formidable foe that has managed to evade global attempts to destroy it over six decades. Armed with the safe, inexpensive drug chloroquine and the powerful insecticide DDT, the WHO launched the Global Malaria Eradication Programme in 1955 with the goal to eliminate the disease within a decade. Billions were spent in distributing the anti-malarial medicines, insecticide-treated bednets and fogging with DDT, but the parasite and mosquito survived new drugs, insecticides and habitat changes to continue to infect and kill people in 97 nations.
Over the past decade, the parasite is steadily developing resistance to every frontline anti-malarial drug.
The parasite is now so entrenched across most parts of India that it can be controlled only with a combination of drugs. India’s National Vector Borne Disease Control Programme (NVBDCP) rolled out the WHO-approved fast-acting combination called artemisinin combination therapy (ACT) in 2010. Under the national programme, ACTs are provided free for all, as are long-lasting insecticidal nets, which stay effective for three years and help in lowering transmission.
ACTs are made using artemisinin-based compounds in combination with other classes of anti-malarials. The ACT combination of artesunate and sulphadoxine-pyrimethamine (AS+SP), for example, is the first-line treatment for uncomplicated P. falciparum malaria. With cases of resistance to AS+SP reported in the northeastern states, the Centre gave its nod to the artemether and lumefantrine (ACT-AL) combination for use in the region in April 2013.
Finishing the job
Adding to the problem is the mosquitoes growing resistance to pesticides, the mainstay of vector (mosquito) control. The Anopheles mosquito has grown resistant to DDT and malathion, but is still sensitive to pyrethroid.
GSK’s malaria vaccine triggers the immune system to defend against P. falciparum when it first enters the human bloodstream and/or when the parasite infects liver cells. The vaccine, however, is only partially effective and at best can help control, and not eliminate, malaria. “The way ahead is rapid-diagnostic testing and using ACTs for treatment to prevent severe illness. That, along with the use of indoor residual spraying and long-lasting insecticidal nets in endemic areas, are the tools we know work against malaria,” says a Union Health Ministry official.