Dengue-like viral keeps doctors guessing

Prithvijit Mitra, TNN, Oct 27, 2014, KOLKATA: Is dengue having a longer run in Kolkata this year? Or, is it a new virus similar to the dreaded vector-born disease that remains undetected in the crucial IgM test?

Physicians are not sure about its identity, but they believe that cases of dengue could well be interspersed with this new viral ailment that matches it till the NS1 test, but takes a different course thereafter. Both, they warn, could be equally dangerous since they spread through mosquitoes and are contagious.

Scores of patients at the Ruby Hospital have tested positive in the initial NS1 test over the last three weeks, but the conclusive IgM test failed to confirm it. The latter screens the antibodies generated by the dengue virus. At Apollo Gleneagles, too, around 10 are being admitted with symptoms of dengue everyday. But more than half of the patients tested negative in IgM test, ruling out dengue. Almost all of them had high fever, body ache, rashes and suffered a platelet drop, though.

"Till recently, we would treat them as dengue cases though they couldn't be officially classified as such. Often, the IgM test would fail to detect dengue for they are not done at the right time. But with the number of such viral fever cases spiraling, we have reason to believe that there's another virus on the prowl. It is carried by mosquitoes as well and is similar in almost every respect to dengue. As doctors, we have no option but to treat all of them as dengue cases," said Amitabha Saha, a consultant at Ruby. The hospital has received around 15 dengue patients over the last fortnight.

Dengue antibodies take four to five days to appear. A blood test done before that fails to confirm the disease. For some patients, it could take even longer to develop antibodies, according to Subrata Maitra, senior consultant at Belle Vue Clinic. "But the symptoms are almost identical. It is possibly some other virus, but it may not be mosquito-borne. On an average, these patients recover in about three-four days of hospitalization, while dengue patients take about a week. But for us, it is far more important to monitor the condition of these patients and ensure that their platelet count doesn't drop," said Maitra.

Some felt that the new virus could be having a few distinguishing characteristics, like a severe and persistent headache. "While in most cases it has been difficult to separate the two, the headache could be a distinguishing feature. It has been common to many patients who tested negative in the IgM test," said Debashish Basu, preventive medicine specialist. While dengue patients usually have severe bodyache, the virus has been triggering muscle and bone pain. But physicians are not sure if the latter is as capable of triggering a platelet fall as dengue. "That is for virologists and epidemiologists to study. But it is important to find that out for it will help us to contain the outbreak," said Maitra.