The town of Serampore, barely 30 km from Kolkata via the Grand Trunk Road, has one of the few municipalities in West Bengal that has learnt from dengue outbreaks in previous years.

“Thousands of people were infected with the dengue virus here last year and four people had died,” said Amiya Mukherjee, chairman of Serampore municipality. “The health department declared an outbreak in Serampore. This was shortly before the Durga puja, which was October 7-11, 2016.”

This year, the Serampore municipal machinery swung into action in February, the season when the breeding cycle of the Aedes aegypti mosquito, the carrier of the dengue virus, begins. All wards were repeatedly sprayed with larvicide, health workers went from home to home, inspecting premises for stagnant water, and issuing instructions to change stored water in open tanks, vessels every week.

“We involved the media and community organisations in creating awareness about dengue,” said Mukherjee. “We also bought an ELISA machine with government funding.”

The ELISA test is the preferred mode of diagnosis of the dengue virus in blood samples.

These measures are paying off. The municipality’s data says there have been no deaths from dengue so far in 2017. In all, around 50 people have been infected with the virus till now.

“Most have recovered and only around seven-eight patients are under hospitalisation now,” said Mukherjee.

Serampore is a rare instance where the National Vector Borne Disease Control Programme’s guidelines for containment of dengue and chikungunya have been implemented. The guidelines require health authorities to target and kill adult populations of the Aedes mosquito by spraying insecticides and thermal fogging. For larval control, measures suggested include shredding of unused or discarded tyres, cups, jars, tins and other small containers, in neighbourhoods and households.

“This is extremely crucial,” said Aparna Mukhopadhyay, virology scholar and professor at Presidency University in Kolkata. “Discarded containers are ideal breeding grounds for the Aedes mosquitoes.”

Yet, almost none of these suggested measures were implemented in Kolkata or the neighbouring districts, where dengue has caused multiple deaths.

State government caught napping

Till the beginning of October, West Bengal has recorded more than 10,600 dengue cases and 19 dengue deaths. Since October 4, the state health department has not released any dengue data, National Vector Borne Disease Control Programme joint director Kalpana Barua told the media on November 7. In a submission to the court earlier this week, West Bengal’s Director of Health Services Biswaranjan Satpathy, said that the number of dengue deaths was still 19 but the number of infections had risen to 18,000.

Kolkata Municipal Corporation workers spray chemicals during a fumigation drive on Nov 2, 2017. (Photo: IANS)

The accuracy of the data that has come in is also questionable. When visited the health department on the afternoon of November 6, health officials were collating the daily dengue report from various districts. One official who was preparing a consolidated state report remarked to another, “The officer from the district has merely copy pasted the report from yesterday instead of writing a new one for today.”

Meanwhile, local media have collated numbers from government and private nursing homes and hospitals, and reports from municipalities and surmised that between October 24 and November 8 alone, 104 people died due to dengue and unknown fever.

Doctors are surprised that the state has not declared a dengue epidemic yet. National health agencies define and epidemic as a sudden increase in the number of cases of a disease above what is normally expected in the population of a specific area. Declaring an epidemic will allow the health department to channel money and manpower towards controlling the spread of the disease and helps prepare health services or increased hospital admissions.

“When the average case load or death rate for a disease goes slightly above the preceding ten-year average, the outbreak is considered an epidemic,” said said Dr Sajal Biswas of Service Doctors Forum, an apolitical association of doctors employed in government hospitals and clinics.

Citing the trend seen in the National Vector Borne Disease Control Programme’s data, Biswas added,“The ten-year average in Bengal was breached three years ago, and the numbers have only been rising.” tried reaching Satpathy about why there had been no declaration of an outbreak or epidemic, but calls and text messages to him went unanswered.

An official at the West Bengal health department said that the health department has no policy on declaring an epidemic. “The department declares outbreaks locally [as in Serampore] when the numbers [of cases] are obviously larger than the previous years,” said the official. “There is no statistical parameter that is followed in this. Instead decisions are taken as the situation develops.”

Even without the declaration of a dengue epidemic, West Bengal should have had better mosquito control measures on the ground. “Dengue is endemic to Bengal, thus requiring the enforcement of the National Vector Borne Disease Control Programme guidelines throughout the year,” pointed out Biswas. “But no one keeps a watch over implementation.”

Most guidelines put in place by the National Vector Borne Disease Control Programme appear to have been rampantly violated.

In the slums and middle class neighbourhoods of Kolkata, residents said that health authorities began fogging, larvicide dispersal and taking other preventive measures only in late September. These preventive actions were often performed just once in a given area. In most rural blocks neighbouring Kolkata, there had been no intensive control measures.

The government’s assurances of dengue control have proven hollow. For instance, in a press conference on October 30, Chief Minister Mamata Banerjee said anganwadi workers would be roped in to undertake a door-to-door inspection and awareness campaign. But Neelima Maitra, former president and representative of All India Federation of Anganwadi Workers and Helpers, said, “In most places, anganwadi workers and helpers have jumped into awareness and inspection programmes at the local level voluntarily, with some financial support from the panchayats. The government has issued no instructions in this regard.”

Dilemma over diagnosis

In early November, some residents of a slum settlement alongside railway tracks in Dhakuria, a locality in south Kolkata, had been diagnosed with “unknown fevers”. Residents of at least three of the sixty-odd hutments said members of their households had been admitted at government hospitals, with such unknown fevers.

At a recent seminar in Kolkata, several doctors observed how doctors and diagnostic laboratories across the state were under immense pressure to not mention dengue in prescriptions and reports, even if the patient was infected with or had died due to the dengue virus. This has resulted in many dengue cases being referred to as ojana jor or unknown fever. Doctors were writing “febrile illness bleeding disorder”, “multiple organ failure”, or simply “fever” as causes of death in death certificates, the doctors at the seminar said.

Some of this is due to official orders pertaining to what diagnostic tests are relevant. Only the ELISA test is considered a valid confirmatory test for dengue. ELISA tests are available only at district hospitals and a handful of sub-divisional hospitals. These hospitals have been under immense pressure since October, when large numbers of urban and rural patients started showing up with fever.

Meanwhile, many laboratories diagnose dengue using the cheaper, faster and more easily available Rapid Diagnostic Test. The National Vector Borne Disease Control Programme’s guidelines note that the commercially available Rapid Diagnostic Test, which tests for a dengue antibody called NS1, has a high rate of error and should not be used for management of dengue. The union health ministry issued a circular in 2016 saying that a patient can only be declared a “probable case of dengue” based on the Rapid Diagnostic Test.

A senior technician from a private diagnostic laboratory who did not wish to be identified said the West Bengal health department last year instructed private labs not to write dengue in reports, after it found that many labs were running Rapid Diagnostic Tests.

CPI-M workers stage a demonstration in Kolkata on Nov 2, 2017 to protest against dengue outbreak in the state. (Photo: IANS)

The health department official said that clinicians may not be writing dengue in diagnostic reports now because of confusion over what the state health department’s instructions mean.

But the absence of a firm denial by the government that the health department has deliberately asked doctors to refrain from attributing fever cases to dengue has only served to obfuscate the scale of the crisis.

Weaker population, stronger virus?

India has had four strains of the dengue virus – DEN-1, DEN-2, DEN-3 AND DEN-4 – in circulation. However, West Bengal’s earlier dengue outbreaks, doctors say, have been caused by the DEN-1 and DEN-3 strains. This year there seems to be an outbreak of the DEN-2 strain infections.

“This year, patients are coming to hospitals with complaints of excessive joint pain that is rendering them immobile within one or to days of the fever setting in,” said Dr Swapan Biswas, who has been part of several dengue-related medical camps organised by doctors associations in the districts. “They are also suffering from distended bellies and acute stomach pain due to capillary leakage. In several cases, patients are brought in in a state of shock, with blood pressure having dipped significantly.”

These clinical symptoms, Biswas said, are different from the symptoms patients had exhibited in outbreaks that occurred over the past two years and match the set of symptoms due to DEN-2 infection.

This outbreak of a new strain that has previously not been seen in the state means an increased risk of mortality, especially among those facing a second dengue attack.

“Antibodies help combat only the same genotype of the virus in case of dengue,” said Aparna Mukhopadhyay from Presidency University. “When a person is infected with another genotype of the dengue virus (like this year), the virus is able to establish itself faster.”

Previous dengue outbreaks through the state have rendered the population weak and more susceptible to an attack by a different dengue genotype.

The Indian Council for Medical Research Virus Unit that is housed under the National Institute of Cholera and Enteric Diseases in Kolkata is the apex referral laboratory in the eastern zone authorised to conduct vector surveillance and analyse the genome sequences of the viruses in dengue positive blood. The institute has, however, not come out with any report on the change in dengue virus strains.

“As long as the data is not in the public domain and we do not know the changed genetic sequence of the virus, how can we possibly probe the reasons for its mutation and strengthening or the measures that can be taken to control the virus,” said a senior scholar researching the dengue virus, who did not want to be identified.