Prevention, Awareness Key To Fight Vector-Borne Diseases

He had developed fever with vomiting on a Monday morning and ceased to recognise his parents soon after. When the treatment meted out by one, then a second hospital proved unsatisfactory, his parents rushed to a higher centre in Ahmedabad, where Sanjay was quickly admitted to the paediatric intensive care, put on a ventilator for breathing distress, and treated for low glucose level and low blood pressure.

Investigations showed that Sanjay’s liver and kidneys had already been severely damaged, all in the space of just over 24 hours. “His liver function tests were 300-400 times above the normal limits and his kidney function was abnormal too, so we started him on continuous dialysis,” Ankit Mehta, the paediatrician and critical care consultant who treated Sanjay, told IndiaSpend.

Over the next 24 hours, Mehta led a team of five doctors and nurses caring for Sanjay, working through the night to normalise his parameters. While his sugar level stabilised and his liver and kidney function improved, testing with a near-infrared spectroscopy showed no response from the brain. The inflammation in Sanjay’s brain continued to increase.

“At one point we realised that Sanjay was brain dead,” said Mehta. “Some hours later, his other vital organs failed.”

Test reports later confirmed that Sanjay had developed acute encephalitis from the Chandipura virus, making him one of 101 children who succumbed to acute encephalitis in Gujarat this year. Acute encephalitis is associated with a very small treatment window of opportunity.

Climate change will exacerbate the spread of vector-borne diseases, research shows. Therefore, preventative measures and community awareness are key to fight these diseases, experts say.

Poor outcomes are normal

Encephalitis, or the inflammation of the brain, symptomatically presents as fever, headache, vomiting, seizures, unconsciousness, altered sensorium and diarrhoea. The virus is transmitted by sand flies, mosquitoes and ticks.

Gujarat has recorded 164 cases of acute encephalitis this monsoon season and 101 deaths this year, translating to a case fatality rate of 62%. While 28 of those who succumbed were confirmed to have the Chandipura virus, 73 succumbed to encephalitis caused by other viruses.

Mehta’s team has cared for three patients during the recent outbreak in Gujarat, India’s worst in two decades. They lost Sanjay but were able to save two children aged 14 and 15.

Mehta isn’t surprised by the high fatality rate. “Acute encephalitis is a serious life-threatening medical emergency associated with poor outcomes, which sometimes happen despite the best of treatment because the disease is fulminant--it progresses very rapidly as it did with Sanjay,” he explained. “The key is to recognise it early and start supportive treatment.”

That is easier said than done, considering the low community awareness of encephalitis, implicated in the 2019 outbreak of acute encephalitis in Bihar, and also in Gujarat prior to this year’s outbreak. Mehta also cited the scarcity of skilled medical professionals to handle such cases, especially in smaller towns, as an obstacle to saving lives.

Building awareness is vital

Gujarat’s first Chandipura virus victim in July 2024 was a four-year-old child from Mota Kanthariya, a village in Sabarkantha district, about 70 km from the district headquarters.

The village has no qualified doctor, only a nurse, and most people who fall sick consult unqualified practitioners, whom the former village sarpanch Vishrambhai Dhanjibhai Kharadi called “compounders”.

“The child’s parents consulted a compounder in the first few days that he was sick,” Kharadi told IndiaSpend. “Only thereafter did they take the child to the government hospital in Himatnagar, the district headquarters, where he was properly diagnosed but could not be saved.”

Kharadi said vector-borne disease awareness and preventative drives started in Mota Kanthariya only after the outbreak made headlines.

Vinayak Patki, who heads the department of paediatrics and neonatology at the Ushahkal Abhinav Institute of Medical Sciences in Maharashtra’s Sangli, saw seven cases of acute encephalitis in children aged one to 16, in the last week of August 2024.

Having seen more cases of acute encephalitis this year than usual, Patki, who is also the secretary of the Intensive Care Chapter of the Indian Academy of Paediatrics, has gotten involved with awareness outreach among doctors as well as the community.

“We need to educate frontline doctors on the red flags, so that they don’t delay referring patients who are likely to need intensive treatment,” said Patki. “Parents must also know what to look out for and be made to understand the seriousness of vector-borne diseases.”

Red flags include persistent fever, persistent headache, giddiness, vomiting without nausea, loss of vision, unstable gait and an altered sensorium.

“We can treat patients if they come to us in a reasonable sensorium,” Patki said, but in cases where the patient already has low blood pressure, bleeding, or seizures that have not responded to the usual anticonvulsant medications, “there is nothing much we can do,” he added. “Most serious cases that come to us as status epilepticus succumb to raised intracranial pressure [the pressure of fluids on the brain; during a seizure, the flow of cerebral blood increases].”

We have reached out to the director general of health services in the Ministry of Health & Family Welfare for comment on any association between climate change and the increase in encephalitis cases, and on the efficacy of preventative measures. We will update this story when we receive a response.

Why children are more vulnerable to acute encephalitis

Whereas dengue, malaria and chikungunya occur among people of all ages, acute encephalitis occurs mostly only among children.

Patki attributed children’s higher susceptibility partly to their inability to properly express their symptoms, “which makes it harder to catch the disease”, and also to the immune debt kicking in after the Covid-19 pandemic.

“Immune debt refers to lowered immunity from less exposure to various pathogens because of less community interaction, as we experienced during Covid,” he explained. “We’ve seen a general increase in viral infections after the pandemic, cases of myocarditis and severe pneumonia needing ventilation, and infants born after or during the pandemic are particularly susceptible to these because of the immune debt.”

Climate change will intensify vector-borne diseases

Acute encephalitis, dengue, chikungunya and malaria are all transmissible by vectors such as mosquitoes, sand flies or ticks.

All of these vector-borne diseases are an outcome of the interaction of abiotic (temperature, rainfall and humidity) and biotic factors (living organisms), explains R.S. Sharma, former head and additional director, Centre for Medical Entomology & Vector Control, National Centre for Disease Control and member, ICMR Task Force on Insecticide Resistance.

Certain conditions, such as higher temperature and humidity, create favourable conditions for vectors to proliferate. In fact, higher temperature as a result of climate change has reduced the incubation period of the parasite causing malaria, thus “posing a risk for disease transmission and a hindrance to malaria elimination efforts”, according to a March 2024 study published in the journal Parasites & Vectors.

Jayesh Katira, deputy director, epidemic in Gujarat’s health department attributed this year’s outbreak in the state to climate change, pointing out that “India is particularly vulnerable to climate change”, and “there is nothing anyone can do to stop climate change”.

In the last few years, India has been seeing growing numbers of dengue and chikungunya cases and deaths due to dengue.

However, steps can be taken to prevent outbreaks. The more intensely parasites and vectors proliferate, the greater is the need for surveillance and awareness.

Vector control is the bedrock of prevention

This year, the New Delhi Municipal Corporation saw fewer cases of mosquito-borne diseases; it has reported a 94% reduction in dengue cases, as a result of better surveillance and awareness.

Vectors can rest and breed both outdoors and indoors, in still water, old tyres, flower pots, the cracks of mud walls, etc. Gujarat’s first acute encephalitis victim lived in a “kuccha” home, a reminder that in the rural parts of the state, the Prime Minister’s Housing Scheme still has achieved only 60.6% of its goal of 902,354 houses.

A comprehensive preventative programme would target all of these resting and breeding spots. Tools for the containment of vector borne-diseases include chemical insecticides, space sprays, fogging, treated bednets and larvicides, biological control methods such as fish that feed on larvae and environmental control, and modification measures such as source reduction, to cite a recent study in the British Medical Journal (BMJ).

Choosing the right preventative tool is important because these methods are increasingly becoming less effective due to reasons such as insecticide resistance, outdoor biting, behavioural changes in vectors for biting and resting, climate change, movement of population, vector incursion to newer areas, limited resources and poor or inadequate usage by the community, according to the aforementioned BMJ study.

Resource shortages and operational challenges can sometimes come in the way of preventative measures.

Anti-larval programmes in municipalities in many cities are ongoing but these face challenges in reaching vectors breeding in large water bodies, said B. Reddya Naik, professor of zoology at University College of Science, Osmania University, Hyderabad. “Controlling vectors when they are in water bodies is critical. Once they spread to the terrestrial environment, they spread much faster.”

The community plays a role in prevention in urban as well as in rural areas.

After the number of cases in the Bruhat Bengaluru Mahanagara Palike’s jurisdiction crossed 7,000 in July straining the health infrastructure and causing hospital bed shortages (which have reoccurred in September), Karnataka declared a dengue epidemic and introduced fines for potential mosquito breeding spots in residential and commercial premises.

“In rural India, community participation is key to prevent outbreaks of vector-borne diseases,” said Naik.

For instance, communities must be educated to adopt measures to prevent the breeding of vectors that cause diseases, such as by cleaning tanks, and these practices should be implemented around the year, not just in the monsoons, Naik emphasised. “We need a change of mindset.”

Intense reactive measures cannot replace prevention

After an outbreak, the focus of the authorities turns to intense reactive measures.

In Gujarat, “as soon as the virus was identified, the administration started to spray with alphacypermethrin in hot spots--villages and areas that saw outbreaks, both in homes and cattle sheds because cattle are a reservoir,” Katira told IndiaSpend. “With the permission of the higher authorities at the National Centre for Vector Borne Diseases Control, we also dusted high-risk areas with malathion to eliminate vectors transmitting malaria and dengue.”

“Spraying alphacypermethrin on the inner walls of homes up to 6 feet yields excellent results, it interrupts the transmission of the Chandipura virus, which is transmitted by sand flies,” said Sharma.

Sand flies are usually not found higher than 6 feet.

An evaluative study, published in August 2024, of the impact of indoor residual spraying on sandfly abundance in homes across Bihar, Jharkhand and West Bengal, concluded that alphacypermethrin, sprayed twice during the transmission season, can reduce the indoor sandfly abundance by 27%.

“Alphacypermethrin is still highly efficacious against sandflies, as far as we know,” said Luc Coffing, assistant professor, Infectious Disease Control, Department of Public Health, Erasmus MC, University Medical Center, Rotterdam, and the lead author of the study.

Katira said that the malathion application “wasn’t done prior to the outbreak of acute encephalitis in July because malathion would be washed out when it rains”.

Building awareness in the community would have withstood the onset of the monsoon.

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