India has been witnessing a deluge of dengue cases in the past few weeks due to heavy rains and flooding in several parts of the country. While monsoon usually registers a spike in vector-borne diseases, this year the cases have grown manifold due to prolonged rainy weather. Dengue must be diagnosed on time to ensure the health threats due to the disease are controlled. There is no cure for dengue, and it is self-limiting. The symptoms can range from mild to severe depending on the strain and how the disease is being managed. Dengue is caused by a viral infection with dengue virus (DENV) and it has four serotypes of the disease namely DENV-1, DENV-2, DENV-3, and DENV-4. The virus is spread from human to human through bite of Aedes mosquitoes.

Most people with dengue are asymptomatic and do not even realise they were infected with the virus. In case of symptoms, they start showing typically 4–10 days after infection and the disease can last for 2–7 days. Symptoms may include high fever, severe headache, pain behind the eyes, muscle and joint pains, nausea, vomiting, swollen glands and rash. People may experience severe abdominal pain, persistent vomiting, rapid breathing, bleeding from gums or nose, fatigue or restlessness even after they recover from fever.

"Dengue fever is a mosquito-borne viral infection caused by four different strains of the dengue virus, known as DENV-1, DENV-2, DENV-3, and DENV-4. While the general symptoms of dengue remain similar for all strains, the severity of the disease can vary depending on the specific strain involved. It's important to note that dengue can progress from mild to severe, and severe cases can lead to dengue haemorrhagic fever (DHF) or dengue shock syndrome (DSS), which can be life-threatening," says Dr M. A. Muqsith Quadri, Consultant - Internal Medicine, CARE Hospitals Banjara Hills, Hyderabad.

DENV-1 to DENV-4: Strain-wise symptoms of dengue

Dr. Quadri breaks down dengue fever symptoms from mild to severe depending on the strain.

Here are the common signs and symptoms of dengue fever, followed by a specific strain-wise breakdown of the symptoms:

DENV-1

This is the most common strain of dengue, and it typically causes mild symptoms. These symptoms may include:

• High fever (40°C/104°F)
• Severe headache
• Pain behind the eyes
• Muscle and joint pains
• Nausea and vomiting
• Rash

DENV-2

This strain is also known to cause mild symptoms, but it is thought to be more severe than DENV-1. Symptoms may include:

All of the symptoms of DENV-1, plus:

• Severe abdominal pain
• Persistent vomiting
• Bleeding gums or nose
• Rapid breathing
• Fatigue/restlessness

DENV-3

• This strain is typically less severe than DENV-1 or DENV-2, but it can still cause serious illness. Symptoms may include:
• All of the symptoms of DENV-1, plus:
• Haemoconcentration (increased haematocrit)
• Low platelet count
• Fluid accumulation in the lungs

DENV-4

This strain is the least common, and it is thought to be the mildest. Symptoms may include:

All of the symptoms of DENV-1, plus:

• Conjunctivitis (pink eye)
• Lymphadenopathy (swollen lymph nodes)

It is important to note that the symptoms of dengue can vary from person to person, and even from strain to strain. Some people may experience no symptoms at all, while others may develop severe illness. If you think you may have dengue, it is important to see a doctor right away.

All you need to know about symptom progression of dengue by Dr Quadri

Here is some additional information about the symptoms of dengue fever:

• The symptoms of dengue usually start 4-10 days after being bitten by an infected mosquito.
• The symptoms of dengue can last for 2-7 days.
• If you have dengue, you are at risk of developing severe dengue. Severe dengue is a life-threatening illness.
• There is no specific treatment for dengue. Treatment is supportive, which means that it is aimed at relieving symptoms and preventing complications.
• There is a vaccine for dengue, but it is not yet widely available.
• If you are traveling to an area where dengue is common, it is important to take steps to protect yourself from mosquito bites. These steps include:

Common symptoms of dengue caused by different strains

Dr. Shuchin Bajaj, Founder and Director, of Ujala Cygnus Group of Hospitals shares a list of common symptoms of dengue

• High fever
• Severe headache
• Pain behind the eyes
• Joint and muscle pain
• Nausea and vomiting
• Skin rash
• Mild bleeding (e.g., nose or gum bleeding)

Severe dengue (also known as dengue haemorrhagic fever or dengue shock syndrome) may have additional symptoms, such as severe abdominal pain, persistent vomiting, bleeding gums, rapid breathing, fatigue, and restlessness.

Dengue is a viral disease caused by mosquito bites of Aedes mosquitoes. Usually 4-10 days after mosquito bite, patient starts showing symptoms such as high-grade fever, severe headaches, body pain, and pain in eyelids while moving the eyes. Although some symptoms are common, in case of mild fever, symptoms subside after 2 weeks of illness. In case of severe dengue fever, patients can go into dengue shock syndrome, platelet counts can fall below 20,000 and symptoms like severe abdominal pain, persistent vomiting, bleeding from nose, gums or other mucous membranes, cold or clammy skin, fluid accumulation, and even organ failure are there. 1 in 20 patients can go into the critical stage if not treated in time, says Dr Ashutosh Shukla, Senior Director – Internal Medicine & Medical Advisor – Max Hospital, Gurgaon.