With a rise in number of dengue patients, scientists at the National Institute of Virology (NIV) have urged Pune Municipal Corporation (PMC) to send blood samples of suspected dengue cases within five days of infection to make it easier to identify the serotype.
“Identifying the serotype is challenging if samples are not sent on time and more importantly they need to be preserved in a cold chain,” Dr Paresh Shah, scientist with the Dengue group at NIV told The Indian Express.
From April, NIV received 839 samples from Pune and across the state and 205 were tested positive for dengue. A total of 697 samples were from Pune and 137 tested positive. Out of another 115 samples sent from states like Gujarat and Kerala, 18 tested positive.
“We need good quality samples that need to be sent early. The civic body initiated a drive urging hospitals to send samples early but so far we have got only 50. We cannot detect the serotype if the virus is not there in the sample. Our team collects samples from hospitals which have higher cases and from the two samples collected by virologists had been identified as Dengue-4 serotype,” Shah said.
When contacted, Dr S T Pardeshi, acting health chief of PMC said they received the letter from NIV and were contacting hospitals to send samples early. “At times people report to physicians on the first two-three days of fever, which is crucial to detect the serotype. We are coordinating with the hospitals,” Pardeshi added.
The presence of four serotypes has become a challenge, Dr Cecilia Dayaraj, head of the dengue group at NIV said in her recent paper on status of dengue in India presented at the WHO South East journal of Public Health. Dengue-1 was seen in 2005 and 2007, Dengue-2 was dominant in 2008 and Dengue-3 in 2009. In 2010 both Dengue-2 and Dengue-3 were co-dominant. Dengue-4 was poorly represented with just one case each in 2009 and 2010; both cases were dengue haemorrhagic fever (DHF), Dayaraj explained.
Although dengue cases showed a steady rise, mortality has reduced over the years. The overall mortality rate of 1.2% in 2007 dropped to 0.25% in 2013. This reduction is probably the result of cumulative effects of better patient management, increased diagnostic capabilities and better reporting, Dayaraj said.