Throughout the Covid-19 pandemic outbreak, the community needs to prevail vigilant against the threat of Dengue Hemorrhagic Fever (DHF). The disease caused by Aedes aegypti mosquitoes began to increase in early 2020, along with the arrival of the rainy season.

Based on data from the Ministry of Health, which starts from 1 January 2020 to 29 February 2020, there have been 13,864 dengue cases with 78 people dead. Some regions have even determined the DBD case as an Extraordinary Event (KLB) such as Sikka Regency and Belitung Regency. Awareness of the dengue threat in all regions must remain a priority, especially in the coming months. Yogyakarta World Mosquito Program (WMP) insect expert, Warsito Tantowijoyo, predicted March and April 2020 as the peak of dengue cases in the city of Yogyakarta.

This prediction accumulated based on Aedes aegypti population data that has reached its peak around January 2020. “The peak of the Aedes aegypti population occurred around January, after which the population will decline. Based on experience, the high season of dengue fever usually begins to occur 2-3 months after the peak mosquito population. This is where we need to be aware of the increasing number of dengue cases,” said Warsito.

Dengue is a mosquito-borne viral disease, widespread through the tropics as it is “influenced by rainfall, temperature, relative humidity, and unplanned rapid urbanization,” explains the World Health Organization (WHO). The species Aedes aegypti is also the vector for other viruses such as chikungunya, yellow fever, and Zika. As climate changes and urbanization increases, the mosquito is finding new places to hatch. “If new areas get warmer, the vector Aedes will expand,” explains the PAHO researcher to IPS. “We can now find it in higher altitudes than before.”

The consequences of the disease vary, notes the WHO in a note on June 23, 2020. The symptoms may range from those similar to the flu to “severe bleedings, organ impairment and/or plasma leakage.” In either case, the virus can also affect women and anemics disproportionately. “Dengue impacts on an individual’s iron levels, which can be especially crucial for pregnant women,” says Angel Muñoz, climate variability researcher at the International Research Institute, which is part of the Earth Institute at Columbia University. “Anemics are more likely to get the disease.”

Basic guidelines for strategic lines of action

Member States are urged to make use of their resources effectively under the present circumstances where staff are also diverted to provide COVID-19 response. This can be achieved by combining activities such as the following: Integrated surveillance: Countries must be encouraged to continue the epidemiological surveillance and provide reports of suspected and confirmed dengue cases.

Integrated surveillance: Countries must be encouraged to continue the epidemiological surveillance and provide reports of suspected and confirmed dengue cases.

• Since clustering of cases is common in both diseases (dengue and COVID-19), efforts must be made to strengthen surveillance and differential diagnosis during laboratory confirmation in each affected locality.
• Prior information of hotspots of dengue should be targeted for intensive vector control.
• Indeed, established clinical surveillance networks for dengue can expand their detection criteria to incorporate COVID-19 symptoms, to maximize the use of resources.
• Sentinel entomological surveillance will help to assess the changes in the risk of vector-borne diseases, and impact of vector control measures.

Diagnostics: Many COVID-19 and dengue diagnostic tests are based on PCR, however they use different reagents and type of sample (oropharyngeal/nasopharyngeal swabs for COVID-19 and blood/serum for dengue). Regarding serological tests, both viruses are not antigenically related (i.e. they belong to a different and distant viral family), therefore cross reaction is an unlikely event.

• In malaria co-endemic areas blood smear test must be done to rule out the presence of malaria in the patient.
• RDTs have shown low sensitivity so the negative predictive value is very low, and a negative result will not rule out a case. Due to this, implementation and use of these types of tests for public health purposes should be carefully assessed, and ELISA should be prioritized for serology.
• Although there is one report of possible dengue RDT false positive results in two COVID-19 cases, there is no evidence supporting antibody cross reactivity.
• Efforts must be made to strengthen virus surveillance and laboratory diagnostic capacity in all countries.

Vector control: Source reduction of mosquito breeding sites and adult control measures should be implemented in areas affected by or at risk of dengue.

• Under the present situation, even during lock-down, households should be encouraged to work together in and around their homes to get rid of stagnant water, reduce solid wastes and to ensure proper covering of all water storage containers. This can be done as a weekly family activity.
• In areas not under lock-down, vector control measures targeting the larvae and the adult mosquitoes need to be implemented and vector control staff should use PPE while carrying out community-based control measures with social distancing.
• Vulnerable groups (elderly, pregnant women, infants and the sick) should be encouraged to use insect repellents and inter sectoral coordination should be initiated to get more support from non-health sectors.
• Additional vector control measures such as larvicide, targeted IRS and indoor space spraying can be used to control dengue outbreaks depending on the resources, capacity and action plans developed at the local level (details are given below).
• Spatial application of insecticides (fogging) is necessary with the aim of rapidly eliminating the adult mosquito population and reducing dengue transmission, and WHO prequalified insecticides are recommended, and preferably based on evidence of susceptibility of the local population of Aedes to the applied products. Indoor Ultra low volume fogging can be used to reduce the use of insecticides and target the intervention.
• The intradomicile application or targeted indoor residual spraying should be selectively directed at resting places of the Aedes aegypti, such as under furniture and on dark, wet surfaces. Precautions must be taken not to fumigate storage tanks for drinking and cooking water. This intervention in treated areas is effective for period of up to 4 months; and can be used in health centers, schools and places of worship.

Community involvement: All efforts should be made to get community support for the prevention of both COVID-19 and dengue.

• Simple IEC materials can be shown through the media (including social media) for both diseases where possible, in view of the lock down.
• Since people are recommended to stay in their homes during the lockdown periods, households should be encouraged to eliminate mosquito breeding sources, both domiciliary and peridomiciliary.
• Highly productive mosquito breeding sites such as water storage containers (drums, overhead tanks, mud pots etc.) should be targeted for prevention of breeding. Other breeding sites such as roof gutters and other water holding containers should also be cleaned periodically.
• Local teams regularly know how to make this information more effective, and sometimes national campaigns and messages are not as effective as local initiatives.
• In areas where schools and colleges have resumed classes, special sessions should be devoted for awareness drive for COVID-19 and dengue prevention. Media campaigns can continue for dengue prevention and control of Aedes mosquito breeding.

Forecasting the second wave, if dengue and COVID‐19 coinfection occurs, the current health crises could surely aggravate further. In developing countries like Pakistan, thousands of people have stopped visiting hospitals or physicians for several weeks and even the outpatient department in hospitals is not properly working due to the COVID‐19 pandemic. In such a scenario, if dengue infection in the coming monsoons reaches to the previous year level, a more alarming health crisis could be triggered. Moreover, there are certain concerns by keeping in mind the weak health care systems.

First, developing countries are at the edge of multiple socioeconomic collapses because there is a lack of specific amounts of diagnostic testing kits which may result in difficulty in early detection of the virus and eventually in preventing the onward transmission.10 Second, due to underfunding and under staffing, there is also inadequate public health care infrastructure.

With such concerns, developing countries are struggling hard to cope with COVID‐19. A significant number of asymptomatic cases and the limited numbers of tests might lead to some undetected cases moving freely and infecting the masses that can eventually result in more clusters of infections. However, to restrain both these epidemics, drastic measures such as greater investment in preparing diagnostic kits, medical supplies, and vaccine development must be taken.