Last updated on 20 October 2021
How do you tell COVID-19 and Dengue Apart?
Most people who contract dengue or COVID-19 have mild illness and can recover at home, feeling better after a week.
Some people, however, are at risk of developing severe illness that can be life threatening and requires hospital-based care that is different for the 2 conditions.
The warning signs for the 2 diseases include:
- Severe dengue: Persistent vomiting, gum (mucosal) bleeding, difficulty breathing, lethargy and restlessness
- COVID-19: Difficulty breathing, persistent pain or pressure in the chest, new confusion, inability to wake or stay awake and bluish lips or face
What are the similarities between COVID-19 and dengue fever?
COVID-19 and dengue fever are both infections caused by viruses. Both conditions can cause fever and body aches in the affected individual. COVID-19 and dengue fever can cause mild to severe symptoms. At its worst, both conditions can lead to damage of multiple organ systems and even death.
If you are experiencing any of the severe symptoms mentioned above, seek medical attention immediately at your nearest clinic or accident and emergency (A&E) department. Further tests or nasal swabs for COVID-19 may be required.
Dengue fever is an illness caused by a virus that ranges from mild to severe in different people. In people who experience mild symptoms, they may be mistaken for other illnesses, such as the flu. Southeast Asia is one of the regions most commonly affected by dengue infections.
How does it spread?
Dengue is spread through bites of infected Aedes species mosquitoes. An Aedes mosquito that bites a person infected with the dengue virus, becomes infected by the virus itself. The virus is transmitted further when the infected mosquito bites another person.
Signs and symptoms
Mild symptoms of a dengue infection include:
- High fever (40°C)
- Muscle, bone or joint pain
- Nausea and vomiting
- Pain behind the eyes
- Swollen glands
Most people recover within a week but some may develop severe dengue that can become life-threatening.
Warning signs and when to seek immediate medical attention
Warning signs of severe dengue fever usually begin within the first 2 days after your fever goes away. They include:
- Severe stomach pain and persistent vomiting
- Bleeding from gums or nose
- Blood in urine, stools or vomit
- Appearance of bruising on the skin
- Difficult or rapid breathing
- Fatigue, irritability or restlessness
See a doctor immediately if you have had fever and develop any of these symptoms.
Coronavirus disease 2019 (COVID-19), is caused by a new virus linked to the same family of viruses that can cause illnesses such as the common cold, SARS and Middle East respiratory syndrome (MERS).
How does it spread?
COVID-19 mainly spreads from person to person when in close contact. This is usually through the respiratory droplets that are released when someone with the virus coughs, sneezes, breathes, sings or talks.
Some cases of airborne transmission have also been reported. This is where a person is infected by the virus that stays in the air for several minutes or hours. The virus can also spread if a person touches a surface or object with the virus on it and then touches his or her mouth, nose or eyes. More needs to be learnt on how commonly do these modes of transmission result in an infection.
Signs and symptoms
Early symptoms of COVID-19 that are common include:
- Loss of taste or smell
Besides these, a range of other symptoms have been reported that vary in their severity. Some people may also experience no symptoms at all.
Warning signs and when to seek immediate medical attention
People who are older and have existing medical conditions may have a higher risk of severe COVID-19.
Warning signs and symptoms can include:
- Trouble breathing
- Persistent chest pain or pressure
- Inability to stay awake
- New confusion
- Pale, gray or blue-coloured skin, lips or nail beds
What are the differences?
Causes and transmissibility
COVID-19 is caused by the novel coronavirus, SARS-CoV-2. As of now, it is still unproven if an individual who previously developed COVID-19 infection will form antibodies that can protect them from getting re-infected in the future.
Dengue is transmitted through the bite of the Aedes mosquito infected with a dengue virus. There are 4 subtypes of the dengue virus, namely dengue virus 1, 2, 3 and 4. Because of these 4 subtypes, an individual can develop dengue fever multiple times.
COVID-19 is spread through exposure to infected droplets produced when an infected person coughs, sneezes, or talks. In contrast, there are a couple of ways that dengue is transmitted. The first is mosquito-to-human, in which an infected Aedes mosquito bites a human, effectively spreading the dengue virus. Mosquitoes, in turn, can become infected when they bite a person infected with the virus. These infected mosquitoes can then spread the virus to other people through its bite. The dengue virus can also be transmitted from pregnant mother-to-child. A pregnant woman already infected with dengue can pass also on the virus to her foetus during pregnancy.
Although both conditions can cause fever, body pains and fatigue, persons with COVID-19 infection can also experience cough, difficulty of breathing, loss of taste or smell, sore throat and colds. In dengue, the other common symptoms include severe headaches, pain behind the eyes, nausea, vomiting, and skin rash.
Who is at risk of developing these diseases?
Risk factors of COVID-19
People are at increased risk for developing COVID-19 if they travel to or live in an area where there is ongoing spread of the SARS-CoV-2 virus. Close contacts of patients that are infected with COVID-19 are also at risk.
Elderly people and those with pre-existing medical conditions such as hypertension, diabetes, heart disease, lung disease, and weak immune systems are also more likely to develop severe symptoms if infected with COVID-19.
Risk factors of dengue
Individuals who travel to or live in tropical areas are at risk for developing dengue fever due to increased exposure to infected mosquitoes. People who were previously infected with dengue virus are at greater risk of developing severe disease when re-infected.
What can you do to protect yourself against these diseases?
How to reduce your risk of getting COVID-19
To reduce your risk of getting COVID-19, it is recommended to avoid crowded areas, practise social distancing, by maintaining a safe distance of at least 1 metre from others when outside, and wearing a face mask when in public.
It is also advisable to practise regular handwashing and avoid touching your face, especially your eyes, nose and mouth.
How to reduce your risk of getting dengue
To reduce your risk of getting dengue, it is recommended to protect yourself from mosquito bites by using mosquito repellent, wearing long-sleeved clothing, and installing mosquito screens in the home.
Eliminating habitats where mosquitoes may breed is also important. Since mosquitoes that carry the dengue virus commonly breed in standing water, covering and regularly clearing water containers of stagnant water are also effective in reducing your risk of getting dengue.
A dengue vaccine is currently available for people aged 9 – 45 years. This vaccine is recommended for use among individuals with confirmed previous dengue infection.
What are the possible complications of these conditions?
Severe COVID-19 infection can lead to complications such as:
- Severe lung disease
- Kidney injury
- Heart problems
- Blood clots, and death.
Severe dengue can lead to complications such as:
- Haemorrhagic fever
- Reduced blood pressure
- Difficulty breathing, and death.
When should you see a doctor?
It is best to consult a doctor if you develop fever with any of the following:
- Muscle or bone pains
- Nausea or vomiting
- Shortness of breath
It is difficult to differentiate COVID-19 and dengue fever during the early stages of the disease. If you are experiencing any of the severe symptoms mentioned above, seek medical attention immediately at your nearest clinic or accident and emergency (A&E) department. Further tests or nasal swabs for COVID-19 may be required.
Article reviewed by Dr Jim Teo, respiratory physician and intensivist at Parkway East Hospital
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