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Monday , August 8 , 2016
 
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Sting of dengue and slackness of response

Dengue has struck early this year with a severity and diversity of symptoms that have had even doctors confused. Metro spoke to medical professionals, public health experts and civic officials to find out why the number of dengue cases has spiralled to four times the average for this time of the year and what the state is doing to combat the sting of this vector-borne disease 

THE SCALE

Six dengue deaths have been reported in and around Calcutta since July, the latest victim being a 10-year old girl from Salt Lake who died of haemorrhagic fever on Sunday.

State health department officials said 73 new infections were confirmed across Bengal on Sunday alone, taking the number of cases recorded since January to more than 1,500. Hundreds of these patients have required hospitalisation, many of them in critical care units. 

In 2015, Bengal had reported 6,000 dengue cases and 10 deaths in the entire year.

UNUSUAL TIMING

Dengue infections usually spiral between August-end and mid-November, for that is the period when occasional rain creates enough freshwater accumulation for the Aedes aegypti mosquito to breed. Heavy monsoon rainfall guards against dengue by washing away mosquito larvae and pupae, but this barely happened in July. 

According to official monsoon data, Calcutta received 17.5 per cent less rainfall this July than the average count for what is supposed to be the rainiest month of the year. Whenever there was lashing rain, it was only in parts of the city. 

August has so far seen rain on most days, but not the heavy and sustained spells that can stamp out dengue.

UNUSUAL STRAIN

The dengue virus has four distinct, yet closely related, serotypes: DEN-1, DEN-2, DEN-3 and DEN-4.

DEN-2, a particularly virulent serotype, has been the villain-in-chief of the dengue story this season. 

Virologists said DEN-2 had been prevalent in Calcutta and other parts of Bengal till 2005. Between 2006 and 2015, DEN-3 was the dominant serotype while DEN-2, although not quite out of the picture, would show up in fewer people.

DEN-2’s comeback has been stronger because most of the population hasn’t developed antibodies yet against this serotype.

USUAL RESPONSE

The municipal authorities were in denial throughout July. It took chief minister Mamata Banerjee’s intervention to shake them out of slumber, although none of the municipal corporations has yet shown the urgency to arrest the spread of dengue through concerted prevention measures.

Metro has been highlighting how potential breeding places of the Aedes aegypti mosquito have escaped the attention of municipal teams across the city. In July, the Calcutta Municipal Corporation was so laidback that it did not organise any special health camp or awareness campaign. 

Planning for health camps started only after a meeting of the mayors of Calcutta, Bidhannagar and Howrah with chief minister Mamata last week. 

Besides failing to respond to the dengue explosion, CMC officials have been accused of underreporting the number of infections. Health workers are required to revisit a place every seven days, but in reality the gap between two visits extends from 15 to 20 days. This is enough time for mosquito larvae grow into adults.

USUAL WARNING SIGNS

  • High fever
  • Rash
  • Nausea/vomiting 
  • Body ache 
  • Lethargy

SEVERE WARNING SIGNS

  • Plasma leakage
  • Haemorrhage 
  • Organ dysfunction

UNUSUAL WARNING SIGNS 

  • Severe diarrhoea
  • Fever with symptoms of common flu like sore throat, cold and cough. Fever subsides after two days, only to relapse. 
  • Hepatitis linked to dengue. The dengue virus usually causes hepatitis in 10 to 20 per cent of patients. This year, the figure is 30 per cent.

OLD MARKER: PLATELET 

Platelet count has become a household topic over the past few years, thanks to dengue. It is a component of blood whose function is to stop bleeding by clumping and clotting blood-vessel injuries. The normal platelet range for children and adults is 1.5 lakh to 4 lakh, but plummets when a person is down with dengue.

Some doctors advice platelet transfusion if the count drops below 50,000. Every dengue season, blood banks face a severe shortage of platelet units because of increased transfusion.

NEW MARKER: HEMATOCRIT

A sharp drop in a person’s platelet count is not the most crucial dengue indicator, say doctors. 

Hematocrit, the volume percentage of red blood cells in the blood, is what one should keep an eye on. If the hematocrit level goes up, it indicates capillary leak, which can lead to shock. Unless there is visible bleeding, most doctors advice plentiful intake of fluids rather than platelet transfusion. Constant fluid intake is known to save a patient from going into shock.

 

Reporting by Sanjay Mandal, Subhajoy Roy and Snehal Sengupta; pictures by Amit Datta


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