The severity of the dengue outbreak experienced by the State during the current season could be due to the presence of co-morbid conditions, delayed access to specialised care, secondary dengue infections, and co-infections with multiple serotypes of the dengue virus.

The intense transmission of the dengue infection is primarily due to the alarmingly high vector density across the State, which should be tackled immediately with intensive control measures involving all stakeholders, according to a report of the Central team, deputed by the Director General of Health Services, which visited Kerala in the last week of July to investigate the outbreak of febrile illness in the State.


Alarmingly high Aedes Aegypti indices had been recorded in most districts, with the House index ranging from 19 to 75 per cent in Thiruvananthapuram district, 40 to 48 per cent in Ernakulam district, and 8 to 62 per cent in Idukki district, the report says. The team included Kalpana Baruah, Joint Director, National Vector-Borne Disease Control Programme; Ratnakar Sahoo, Professor of Medicine, Ram Manohar Lohia Hospital, New Delhi; and B.V. Tandale, Scientist-D, National Institute of Virology (NIV), Pune.

The team had collected 37 serum samples for analysis at NIV, Pune, of which 13 were found positive for dengue virus and two for chikungunya. Within the 13 dengue positive samples, the NIV detected three virus serotypes: DENV 1, DENV 2, and DENV 3. The NIV is continuing with its studies to ascertain if any genetic variations have occurred in the virus serotypes circulating in the State, the report says.

The NIV’s findings about the co-circulation of various virus serotypes in the State concur with the findings of the Rajiv Gandhi Centre for Biotechnology, which had processed 147 serum samples during the current outbreak and found DENV1 in 54 samples, DENV 2 in 11 samples, DENV 3 in 10 samples, and DENV 4 in 18 samples.


The Central team had visited the paediatric wing at SAT Hospital and the medicine wing at the Thiruvananthapuram Medical College Hospital, Thiruvananthapuram General Hospital, Balaramapuram primary health centre, and Kollam district.

They have pointed to the need for better documentation of the clinical course/progression of infection in patients and final diagnosis. In the case of many patients, case records are not complete, the report says.