Doctors warned that reinfections can cause serious illness, often requiring intensive care, and may prove fatal if not diagnosed and treated promptly. Case in point: a 26-year-old patient died in a Kolkata hospital on October 20 after catching the virus thrice in five years.
“Around 30% of patients, whose infection history could be traced, had dengue before,” said Nishant Agarwal of Charnock Hospital in Kolkata. History has repeatedly demonstrated that a second dengue infection within 18 months of the first can have grave clinical consequences, said Dr Arpita Dwivedy of Hiranandani Hospital in Mumbai.
More than 80% patients in Pune, considered a hotbed of dengue in Maharashtra, have been diagnosed with reinfection this season, said Dr Rajesh Gadia of KEM Hospital. “But only about 10% of them have developed complications. Fatalities can be checked with appropriate and adequate medical management.”
Patients need rest and to be monitored and treated for symptoms, including high fever, headache and muscle and joint pain, dehydration, skin rash, exhaustion and a low blood platelet count. The disease has no cure, other than timely care. A 28-year-old patient and her doctors at Gleneagles Global Hospital in Chennai will vouch for that.
She was wheeled in with high fever, pain and fatigue. A series of tests established a reinfection. “Her NS1 was positive as expected. This indicated a current infection. A more confirmatory diagnosis is IGM, which was also positive. The sign of a previous infection, seen in IGT, returned positive as well,” said Dr Subramanian Swaminathan. After aggressive therapy, she recovered and was discharged.
Bengal health authorities are trying to detect past infections in patients after an uptick in repetitive surges. “In our unit, we could trace previous infections in about 50% of patients,” said Dr Rimita Dey of Kolkata’s Ruby General Hospital. “More than 30% of dengue cases in children are reinfections,” said Dr Prabhas Prasun Giri of Institute of Child Health, Kolkata.
But reinfections are not easy to detect. A senior physician in Mumbai said: “Dengue is undercounted in metros. If the first bout is mild, it may go unnoticed. Often, people don’t get tested, or the test itself is not performed in the right window. So the findings can be misleading.”
Dengue is transmitted when its main spreader, the Aedes aegypti mosquito, bites someone who is infected, and then bites another person. Doctors, going back to Hippocrates, have long connected disease to weather and it can’t be any truer with the dengue-carrying mozzies that are daytime biters, thrive in hot conditions and breed in clean water — a reason why outbreaks trail the monsoon or heavy rainfall.
“Dengue is endemic in most parts of the country. Several people have been infected before. So, the population at risk of catching it again remains high,” said Dr Swaminathan.
Dengue is caused by five serotypes or virus strains — DENV1, 2, 3, 4 and 5, the fifth was found in 2013. DENV3 was widespread in samples collected in Thiruvananthapuram, while a PGI Chandigarh doctor said DENV2 is the most prevalent in Punjab.
An infected person develops protective immunity against that particular strain, but not to the others. “But unlike Covid, one dengue serotype would give only partial immunity to another. Antibodies from a previous infection will not kill the virus in a subsequent infection,” said Dr Anish TS of Government Medical College in Kerala’s Manjeri.
An antibody spike can cause more harm than good. Dr Jugal Kishore of Delhi’s Safdarjung Hospital said a repeat infection could induce the body to produce a large amount of antibodies. “Excessive antibodies attack blood cells and trigger shock (sudden blood pressure drop) and dengue haemorrhagic fever, conditions that can lead to death,” Dr Kishore said. “The dengue virus is self-limiting. But when platelets fall significantly, bleeding becomes a serious condition.”
Comorbidity increases the chances of death from dengue, according to AIIMS Bhubaneswar director Dr Ashutosh Biswas. “Severity is measured in three parameters. Bleeding (platelet loss), capillary leakage and organ infirmity. In case of severe inflammation, the body releases chemicals that lead to multi-organ failure.”
(With inputs from Kolkata, Delhi, Pune, Mumbai, Chennai, Thiruvananthapuram, Chandigarh).