From Sri Lanka to China: What India Can Learn From the World About Combating Dengue, Malaria

How outbreaks of vector-borne diseases manifest in different parts of the world often vary, as do the ways in which governments try to deal with the challenges.

By Aniruddha Ghosal

On November 8, Sri Lanka’s health ministry warned of a large-scale dengue outbreak, with over 60,000 patients and 80 deaths this year. The past months have also seen Pakistan battle a similar flare-up, with over 45,000 infected and 80 dead. Bangladesh is also facing its worst-ever dengue outbreak since 2000, with more than 92,000 cases reported until early November. India, on the other hand, had reported over 91,000 cases and 82 deaths until October 31.

Health officials in these countries have all pointed at the delayed monsoon — which increases the breeding ground for the dengue virus-carrying Aedes aegypti mosquito — as the prime cause behind the outbreaks. But until recently, the mosquito species was restricted to the tropics. With climate change, its habitat range has increased and increasingly vector-borne diseases are becoming a global problem.

From other countries in Asia to the Americas and Africa, the incidence of vector-borne diseases has largely increased. Often, these diseases are linked to poverty, and poorer individuals are often more at risk because of their social or environmental conditions (for instance, slums are often situated in low-lying areas where breeding sites of mosquitoes proliferate) or because they don’t have access to preventive interventions and services. The challenges are myriad and although the problem of vector-borne diseases and climate change isn’t new, how it manifests in different parts of the world often varies. As do the ways in which governments try to tackle the problem.

Lessons From Lanka

While the incidence of dengue is spreading to new countries, the incidence of other diseases, like malaria, is decreasing at the global scale — but remaining stable or even increasing in specific locations. Sri Lanka, for instance, declared itself free of malaria in 2016, after seven decades of strife against the disease. Dr H.D.B. Herath, former Director, Anti Malaria Campaign of Sri Lanka is often credited as the man behind Sri Lanka’s success. In an interview with News18, he said that the country “really started the control of malaria from 1999”. “In 1999, we had a drastic reduction of malaria from 1999, and then the emphasis was on eliminating the disease. We were mopping it up from the country and ensuring that it couldn’t be reduced,” he said.

This is key for a country like India where the topography and climatic conditions are varied and these diseases are turning up in unexpected corners. Take, for instance, the case of Uttarakhand. A recent study found that increased temperatures since 1990 had resulted in an extension in the window of malarial transmissions, and it also found “evidence of occurrence of malaria cases…in areas hitherto free from malaria.” Ramesh C. Dhiman, one of its authors told News18 that since these insects are cold-blooded, the development of the pathogen in their body was also dependent on temperature. “If the temperature is too low or too high, neither the insect will be able to develop properly nor the pathogen. Some areas which are colder, particularly in Himalayan region, may not be suitable for transmission of a VBD now, because of lower temperature than the required threshold, but with climate change, such areas may become suitable,” he warned.

Representative Image: Studies in India have indicated that dengue and malaria are slowly, but steadily spreading to the Himalayan states, where it had earlier been too cold for the insects to survive. (Photo: Reuters)

Herath added that after the caseload became manageable, the country began attending each and every case individually to prevent the spread of the disease to other patients. But apart from this, Herath said that they also began separating the local cases, from those that were imported. “This was done so that we could monitor the local cases, and ensure that those went down and also ensure that the imported cases don’t give malaria to the locals,” he said. Now Sri Lanka is constantly on the lookout for accidental cases and it takes “blood sacks” as proxy. “All blood donors are screened for malaria…approximately 300,000 people are screened annually. Pregnant mothers are also checked,” Herath added.

While monitoring cases similarly in India might be untenable, officials admitted that migration was a key factor, about which they knew little. “Each time, we have a dengue outbreak in Cuttack in Odisha…it is immediately after a similar dengue (outbreak) in Kolkata in West Bengal. The two cities are linked via trade and disease,” said an official of the National Vector Borne Disease Control Programme.

Government Responses to a Global Problem

China, meanwhile, hasn’t seen a single indigenous case of malaria since August 2016 — an incredible feat considering the country has seen an estimated 30 million cases of malaria since the 1940s and has also seen 300,000 deaths. China had set itself the target of eliminating malaria by 2020. Following this, 13 ministries — including those representing health, education, finance, research and science, development, public security, the army, commerce, industry — joined hands to end malaria. The official added, “This is the only way to go about it. Vector-borne diseases aren’t just a problem for the health department. Why shouldn’t other ministries join in? What about the forest department, or the education department, or the social welfare department.”

China has also implemented a strict and highly effective surveillance strategy that identifies and stops malaria rapidly before the cases can be spread. Known as “1-3-7”, it hinges on timelines that need to be followed to the hour. On day 1, any malaria cases must be reported, on day 3, the Centre for Disease Control and Prevention has to confirm, investigate and determine the risk, and on day 7, it will take measures to ensure that there is no further spread such as testing other members of the community for the disease.

Representative Image: An eight-year-old boy sits inside a mosquito net in Kolkata. Nets, especially those that have been treated with insecticides, have been key in the reduction of malaria cases in Odisha. (Photo: Reuters)

Dhiman argued that the “only shortcoming” in India’s routine surveillance for detection of malarial cases “is that all the cases treated by private practitioners are not taken into account. The surveillance system needs to be strengthened to address the issue of actual burden.” He added that with the goal of malaria elimination and cases dropping in different regions, complacency could set in. “Therefore, an early warning system to detect outbreaks is very much needed. We are making headway to develop such a system for addressing the early detection of outbreaks of malaria,” he said.

Increasingly though, governments are reacting to changes in weather and issuing public health alerts. For instance, at Laos — where, as per reports, over 37,000 people have been infected with dengue — the government had earlier this year referred to its weather forecasts while issuing public health alerts. This has been replicated elsewhere, where the health departments are increasingly working in tandem with the meteorological departments to better predict potential crises. In Delhi, for instance, an official told News18, “The health department rolls out a summer plan, a monsoon plan, and a winter plan. The emphasis is to work in tandem and be able to give people the right information at the right time.”

But Sarkar warned against giving climate change too much importance. “Climate change should not be used an excuse,” he said, adding that it was a “factor” — but doesn’t change the ground realities of control vector-borne diseases. “Yes, the vector-borne disease will increase…these are complex diseases and this is one component, a single agent within the chain of transmission,” he said.

(This story was produced with the support of Internews’ Earth Journalism Network)


Reported by - Aniruddha Ghosal
Produced by - Fazil Khan
Lead Image - Reuters