New Delhi: The Covid-19 pandemic may have worsened the clinical course of dengue, a vector-borne disease that is endemic in the country, a crucial study from India, carried out by scientists attached with a government-run institute, has suggested.
The analysis by scientists at the Translational Health Science and Technology Institute (THSTI) under the central government’s department of biotechnology, titled “SARS-CoV-2 antibodies cross-react and enhance dengue infection” has been published in bioRxiv, the preprint server for medical sciences. The study is yet to be peer-reviewed.
It found that anti-SARS-CoV-2 antibodies acquired from natural infection in humans or through experimental immunisation in animals were cross-reactive with DENV-2, one of the virus serotypes that cause dengue, and had the potential to enhance the dengue infection in animal cells.
“This study is the first to demonstrate that anti-SARS-CoV-2 antibodies can cross-react with DENV-2 (dengue virus 2) and can enhance its infection through antibody- dependent enhancement (the ability of antibodies from a previous infection to help a virus infect greater numbers of cells than it would have on its own),” says the study.
These findings have implications for SARS-CoV-2 vaccine development and deployment strategies in regions where dengue is endemic, it adds.
A senior scientist from Indian Council of Medical Research (ICMR) who did not wish to be named said the latest evidence may be a crucial link in understanding why dengue cases, most of them severe, are now being seen throughout the year, instead of just during the post-monsoon period.
“This scientific suggestion should be examined and monitored closely,” the scientist told ThePrint.
Dengue’s worsening trajectory
Dengue, which is reported from across India now, is mainly spread by Aedes Aegypti mosquitoes and, to a lesser extent, by Aedes Albopictus mosquitoes.
The disease can be caused by any of the four dengue virus serotypes (DENV 1-4), each of which can cause dengue fever or severe dengue.
For many patients, the symptoms include high fever, headache, vomiting, muscle and joint pain accompanied by skin rashes and itching. But in some, the disease can be severe, leading to dengue hemorrhagic fever, in which case there can be bleeding, low platelet levels and blood plasma leakage or dangerously low blood pressure.
Till 17 September this year, a total of 94,198 dengue cases have been reported so far while 91 patients have succumbed to the disease, according to data maintained by the Directorate General of Health Services under the health ministry.
Officials in the ministry said data for the last one month is awaited from states for a clear picture of the spread of the disease this year.
In 2022, a total of 2,33,251 cases of dengue and 303 related deaths registered across India, while in the previous year, 1,93,245 people caught the infection, 346 of whom succumbed as a result.
Some clinicians maintained that a sharp rise in dengue cases is being reported during the ongoing season in many parts of India.
“The country is currently facing a major challenge due to rising dengue cases,” says Dr Kiran G. Kulirankal, assistant professor in the department of general medicine with Amrita hospital in Kochi.
While factors like increased global trade, travel, urbanisation, overpopulation and climate change, besides conditions apt for vector population growth have contributed significantly towards making dengue an annual epidemic in parts of southeast Asia, he says, the latest evidence linking dengue and Covid-19, may be important going forward.
Need for more studies
ADE is a phenomenon seen in viral infections like dengue and Covid-19 where antibodies generated in response to one virus may enhance the entry of a different, but related virus leading to a more severe infection, Kulirankal explains.
“This occurs because of the ability of the antibodies of the first virus to bind to the second virus in order to ineffectively neutralise it…(but) it might even make it easier for the second virus to infect cells, boosting its multiplication leading to a severe form of the illness.”
Newer studies have highlighted this phenomenon and postulated worsening dengue epidemics in the post-Covid era, he points out.
“More studies will have to be carried out to refine our understanding of these interactions and to adapt to health guidelines accordingly,” says the clinician.
According to Dr Vikas Maurya, director and head of pulmonology with Fortis Hospital in Delhi’s Shalimar Bagh, the clinical outcome for many diseases may have gone worse in the post-pandemic era.
“And this phenomenon isn’t limited to respiratory issues but extends to other organs and diseases,” he says, adding that more scientific projects should be undertaken to understand the correlation between Covid-19 and dengue better as shown by the latest study.
(Edited by Amrtansh Arora)