The long-term health risk of recovering from dengue is higher than that of Covid-19

People who contracted dengue and recovered are more likely to suffer long-term health complications nearly a year later than those infected with Covid-19, according to findings from a nationwide study led by Nanyang Technological University, Singapore (NTU Singapore).

Specifically, people who have been infected with dengue have a 55% higher risk of cardiovascular complications, such as irregular heartbeat, heart disease, and blood clots, compared to people who became ill with COVID-19 and recovered.

Based on tests and medical claim records of 11,707 residents with dengue and 1,248,326 residents with COVID-19 (Delta and Omicron variants) in Singapore between July 2021 and October 2022, the study looked for newly emerging health problems related to the cardiovascular, neurological and immune systems that appeared 31 to 300 days after infection. The research team said the prevalence of dengue and COVID-19 in the study period provided a unique opportunity for comparison.

This study has been published in. Journal of Travel Medicine Due in July 2024, it is the first study to examine the long-term risk of multiple health complications following dengue and the first to differentiate between the risk for dengue and COVID-19 patients post-recovery.

The study was conducted by researchers from NTU's Lee Kong Chian School of Medicine (LKCMedicine), Ministry of Health, Singapore, Singapore General Hospital, National Centre for Infectious Diseases, Singapore, and National Environment Agency.

“We were motivated to conduct the study because of the increasing geographic range of dengue due to climate change,” said Lim Jue Tao, lead author of the study and assistant professor of infectious disease modelling at LKCMedicine. “Dengue is one of the most common vector-borne diseases globally, and the long-term health problems caused by dengue can substantially increase the healthcare burden of the infected individual and the country.”

“We also decided to compare outcomes with those of people who recovered from COVID-19 as our previous work suggested an increased risk of similar long-term health complications. Overall, our study underscores the need for people to protect themselves against dengue in their environment and can be a resource to support public health planning.”

Statistical analysis of their data by the researchers showed that people who had dengue had a higher risk of developing long-term health complications than COVID-19 patients – the long-term risk of any type of cardiovascular complications was 55% higher in dengue patients than in COVID-19 patients, the risk of cognition or memory disorders was 213% higher, and the risk of movement disorders was 198% higher.

The risk of complications in dengue patients was compared with those suffering from COVID-19, as previous research has already suggested an increased risk of similar conditions in individuals recovering from COVID-19. Hence, comparing the health issues faced by patients from both groups after recovery provides unique insights into the need for post-acute management and healthcare planning of patients.

The risk is the percentage increase in the probability of developing a specified cardiac or neurological complication in the 300 days following a dengue diagnosis compared with a COVID-19 diagnosis.

The study found that people with dengue had a 55% higher risk of long-term cardiovascular complications, such as dysrhythmias, ischemic heart disease, and thrombotic disorders (101 of 11,166 patients, or 0.9%), compared with those who recovered from COVID-19 (6494 of 1,206,208 patients, or 0.5%).

Dengue patients had a 213% higher risk of cognitive and memory impairment than COVID-19 patients (39 out of 11,632, or 0.3%, in the dengue group vs 1749 out of 1,239,104, or 0.1%, in the COVID-19 group).

Additionally, the risk of new extrapyramidal (movement) disorders was 198% higher in dengue patients when compared with recovered COVID-19 patients (25 out of 11,610, or 0.2%, in the dengue group, compared to 1270 out of 1,238,195, or 0.1%, in the COVID-19 group).

Commenting as an independent expert, Professor Kwok Kin-on, infectious disease epidemiologist at The Jockey Club School of Public Health and Primary Care, Chinese University of Hong Kong, said, “This study is significant as it provides the first comprehensive comparison of post-recovery health issues between dengue and COVID-19 patients, providing valuable insights for healthcare planning and patient management. Additionally, the findings underscore the need for increased vigilance and targeted interventions for dengue recoveries to minimise long-term health impacts.”

The researchers said the study has its limitations. It only involved tracking adults aged 18 and older, meaning the study findings cannot be generalized to the pediatric population. Individual susceptibility to COVID-19 and dengue, such as genetic, behavioral or environmental factors, which may affect risk estimates, were also not considered.

In future research, the team of researchers will compare the risk of long-term health complications due to different dengue serotypes (variants) and the economic costs of these complications.