Viral resistance, SARS CoV-2 antibody caused dip in dengue cases in Tamil Nadu during pandemic, says DPH study
As part of the study, 5,577 human serum samples from 186 clusters and 13,464 mosquito pools collected from the environment were subjected to detailed laboratory investigations.
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CHENNAI: To determine the reasons behind low prevalence of dengue during the COVID-19 pandemic, the Department of Public Health and Preventive Medicine (DPHPM) and State Public Health Laboratory, Chennai, conducted a community-based, serosurvey in December 2021 to compare the antibody levels against the dengue virus (DENV) and SARS CoV-2 in Tamil Nadu.
The study revealed that the decline in dengue cases during the COVID-19 pandemic (2020-22) appears to be attributed to the possible viral interference and the neutralising effect of SARS CoV-2 immunoglobulin G (IgG) antibody against DENV.
Despite having different routes of entry into their host, both viruses have similar pathogenesis, overlapping clinical presentations posing diagnostic predicaments and patient management.
As part of the study, 5,577 human serum samples from 186 clusters and 13,464 mosquito pools collected from the environment were subjected to detailed laboratory investigations. The study demonstrated that the seroprevalence of dengue was very low in the community with 4.12% for DENV IgM and 6.4% for DENV IgG.
Dengue burden in the community was ascertained by the seroprevalence of the DENV antibodies across Tamil Nadu. The anti-SARS-CoV-2 IgG antibody level remained high at 87.3%.
Co-author of the study Dr TS Selvavinayagam stated, “Such integrated mosquito-human sampling across a specific geographical area could help assess the spatial seroprevalence pattern and assist in identification of hot-spot regions of vector circulation. Such regions can be closely monitored, and appropriate vector-control measures can be implemented to prevent outbreaks.”
In a message to the public, he said that currently there was a spike in fever cases among all the age groups due to the monsoon season. “While the incidence of dengue is under control and Aedes mosquitoes being the principal vector for the transmission of dengue, source reduction of vector mosquitoes is the important message conveyed to the public to reduce the burden in the community,” he added.