While COVID-19 has taken the whole world by storm, countries endemic for dengue have been hit by a double epidemic as the year progressed.
West Malaysia is currently in the post-monsoon season and East Malaysia will soon enter the post-monsoon season, which is the peak for dengue outbreaks.
This double epidemic is dangerous because both viruses present similar symptoms (fever, cough, and muscle aches) and are cross-reactive on rapid tests, making it difficult for doctors to differentiate them.
Both viruses trigger similar antibodies that are detected in serological tests. As such, false-positive results can occur for COVID-19 among dengue patients and, conversely, dengue among COVID-19 patients. Two patients in Singapore who presented with dengue symptoms and tested positive on rapid dengue tests were confirmed to have COVID-19 after further testing.
Diagnosis is further complicated by the possibility of co-infection. The first case of co-infection was reported in Reunion Island in March 2020. Since then, many dengue-endemic countries, including Malaysia and Indonesia, have reported such incidents. Testing and management of co-infected patients can be complex, as it has only recently emerged in case reports.
Misdiagnosis can cause the actual infection to be ignored. Potentially missing out COVID-19 leads to further spread of the contagious virus as precautionary measures are not taken. While severe dengue has a mortality rate of 2%-5%, left untreated, the mortality rate is as high as 20%.
In Malaysia, Selangor is one of the states that has been dramatically hit with both COVID-19 (9,761 cases in the past 14 days as of 2nd January 2021) and dengue fever (43,848 cases from December 2019 until 2nd January 2021).
The region has been a hotspot for dengue outbreaks for decades. It is crucial for Malaysian public health authorities to closely monitor the intersection between COVID-19 and dengue outbreaks. Any co-infections should be reported in daily reports on COVID-19 so that the public is aware of this phenomenon.
Improved surveillance reporting will also guide health care workers in providing appropriate testing and management. Severe COVID-19 infections appear to be predominantly in older persons whereas dengue primarily affects children and young adults in most dengue-endemic countries including Malaysia.
In Singapore and Taiwan, dengue has recently become a major cause of morbidity and mortality among the elderly. In dengue-endemic countries including Malaysia are at risk of being infected by both COVID-19 and dengue. Healthcare providers should be aware of this and ensure protection and appropriate care for the elderly.
To tackle the issues of misdiagnosis it is important that affordable rapid tests which are capable of differentiating COVID-19 and dengue viruses with high sensitivity are provided to the dengue-endemic countries starting with their hotspots. Until then, laboratory testing is needed to correctly differentiate the two viruses.
There is a need to allocate more funding to laboratories and ensure that they have sufficient capacity for testing both dengue and covid samples, and not delay release of results.
It is also vital to ensure that COVID-19 efforts do not take resources away from dengue control and prevention. Both the diseases can co-exist in an environment and also co-infect individuals.
The outbreak of dengue, endemic in low-middle income countries during the COVID-19 pandemic is detrimental as it threatens to overwhelm a healthcare system under tremendous stress.
To facilitate the screening of COVID-19 and dengue in hotspots in Malaysia, like Sabah and Selangor, the Ministry of Health should allow medical graduates to volunteer in treatment centres or even carry out public health activities, such as screening and giving public health education. This will reduce the workload on the already overworked and exhausted nurses and doctors in these regions.
Additionally, it will reduce the number of nurses the Ministry of Health has to send in these regions for simple tasks like screening and they can instead be allocated in hospitals to care for the critically ill patients. Since the clinical presentation of both the diseases are similar and can only be differentiated through laboratory testing, countries should focus on preventing the spread of the diseases until more sensitive diagnostic tools are created.
A fairly new way of preventing dengue outbreak is through the release of Wolbachia infected mosquitoes in hotspots. Wolbachia is a type of bacteria that naturally infects mosquitoes and reduces their capability of spreading dengue by at least 40%. The progress of the Wolbachia project, which was successfully piloted in Malaysia in 2019, should not be abandoned.
Dengue-endemic countries like Malaysia should take the heightened focus on infectious disease transmission during COVID-19 as an opportunity to prevent the spread of these diseases. Public health messaging about COVID-19 and infectious disease transmission at a community level is very important to make the people aware of the situation and help them tackle the co-epidemic.