A seasonal infection like dengue can transform into a serious coinfection if one gets infected with COVID-19 simultaneously or vice versa. This article is the second part of our new series- COVID-19 co-infections that focuses on the diagnostics, considerations for management of COVID and dengue.

For our comprehensive coverage and latest updates on COVID-19 click here.

Co-infection with COVID-19 & dengue

Pathogenesis

Dengue fever and COVID-19 share a number of pathogenic and clinical characteristics, making differentiation between the two illnesses extremely challenging. ADE (Antibody-Dependent Enhancement) has been documented for both dengue and SARS-CoV-2 viruses, resulting in an increase in the severity of illness and the number of sequelae. Both viruses are RNA viruses and have some pathogenic characteristics, finally resulting in the production of cytokines and chemokines and also impairing the integrity of the vascular endothelium, resulting in vasculopathy, coagulopathy, and capillary leak. Numerous processes can account for the signs and symptoms found in co-infected individuals, however, the majority will exhibit the following characteristics: Antibody-dependent enhancement (ADE), cytokine storm, vasculopathy, and coagulopathy.

Clinical characteristics

Both diseases, dengue and COVID-19 appear as a brief febrile illness with thrombocytopenia and shortness of breath, however, respiratory symptoms are more prevalent in COVID-19 and bleeding signs are more prevalent in dengue. Leucopenia or a normal leucocyte count is detected during routine testing for both disorders. A decrease in platelet count is a characteristic of dengue illness, but it is also present in a considerable proportion of COVID infections. There are reports in the literature of cases where dengue serology was originally positive but later revealed to be positive for COVID-19 using RT-PCR, suggesting that dengue serology might be mistakenly positive in COVID-19 patients.

As a result, more specialised tests for each illness is required, such as throat swab RT-PCR for COVID-19 and ELISA-based dengue NS1 antigen or serology for dengue diagnosis. Within the first five days after the beginning of fever, serum samples for NS1 antigen were negative, indicating that positive dengue serology was more likely to be a false positive result and not co-infection. As a result, caution is required while diagnosing co-infection.

Both COVID-19 and dengue infection are associated with coagulopathy and vasculopathy, with coagulopathy being more prevalent in formal infections, which has resulted in the widespread usage of Low Molecular Weight Heparin (LMWH). Numerous studies have suggested a higher risk of thrombosis in COVID-19, prompting recommendations for the use of LMWH in mild to severe instances. However, when dengue co-infection occurs, which is frequently associated with thrombocytopenia and an increased risk of bleeding, the usage of LMWH becomes problematic.

Similarly, because of increased capillary leak and increased third space fluid loss, conservative fluid administration, which is the cornerstone of dengue care, may not be suggested as clearly as it has been suggested for COVID-19 in the absence of shock.

Clinical considerations for co-infection with dengue and COVID-19

The following are some basic precautions to take in the event of co-infection with dengue and COVID-19:

1. When co-infection is suspected, it should be ruled out promptly using an appropriate diagnostic tool in order to commence appropriate specialised care and therefore decrease morbidity and death.
2. Strengthening primary health care is critical for managing dengue through early clinical diagnosis and recognition of warning signs of dengue severity (abdominal pain or tenderness, persistent vomiting, clinical fluid accumulation, mucosal bleed, lethargy or restlessness, liver enlargement >2 cm, and increase in haematocrit).
3. Mild to moderate dengue and COVID co-infected patients should be constantly followed, particularly in a hospital setting, as they can rapidly advance to a severe stage and should be referred to a higher centre at an early stage by identifying warning signals.
4. Simultaneously, all secondary and tertiary level hospitals should be prepared to deal with severe dengue and COVID infections.
5. These approaches will assist in preventing the progression of disease to severe dengue and mortality, hence reducing the number of patients referred to hospitals and avoiding saturation of these facilities, as well as critical care units.

Considerations for certain treatment interventions

Specific treatment alternatives and their use in co-infection instances include the following:

1. Fluid therapy- The amount of fluid to be provided in co-infection cases is determined by the patient's haemodynamic condition and degree of severity. For the majority of co-infection cases, one may follow national recommendations for clinical therapy of dengue fever. Only in the presence of SARI with COVID-19 should we exercise caution with intensive fluid administration, as this results in a deterioration of oxygenation. In such instances, close clinical monitoring of fluid status is necessary. For early resuscitation of COVID-19 patients in shock, aggressive fluid resuscitation is suggested.
2. LMWH- Due to the increased risk of thrombosis, LMWH is being utilised and has been included in the National recommendations for the therapy of moderate to severe COVID-19 patients. Once the platelet count falls below 1 lakh, we must exercise extreme caution with the administration of LMWH, which may be withheld depending on the patient's clinical status. The decision to provide LMWH and the dosage should be made in conjunction with close monitoring using D-dimer readings. LMWH must be discontinued immediately in any incidence of co-infection with active bleeding.
3. Corticosteroids- Steroids, particularly dexamethasone, have been demonstrated to be beneficial in severe COVID-19 instances and are thus advised. Dengue fever is a viral infection, and hence its progress will be unaffected. As a result, the usage of steroids may be continued in accordance with COVID-19 management criteria.
4. Tocilizumab- It should be used in accordance with national COVID-19 management recommendations.
5. Antivirals- They must be utilised in accordance with COVID-19 management recommendations and other supportive measures are to be maintained in accordance with current standards.

This article is part of our new series on managing COVID-19 coinfections. Stay tuned for a new update every week. To read the first part, click COVID-19 & seasonal illness- Protocol for determining co-infection

Disclaimer- The views and opinions expressed in this article are those of the author's and do not necessarily reflect the official policy or position of M3 India.

The author is a practising super specialist from New Delhi.