Dengue is the most common mosquito-borne, viral disease in the world. Dengue virus is a single stranded positive polarity RNA virus, belongs to the family Flaviviridae. 

The Den-2 and Den-3 variants of dengue are active this year and of the two, Den-2 is more prominent, according to the Institute of Epidemiology, Disease Control and Research.

Analyzing a limited number of samples it has been found that 62 per cent of the patients have been infected with dengue variant DEN-2.

According to the Directorate General of Health Service, 34 dengue patients have died this year, with the number being 21 in just June so far.

The Dengue Serotypes

According to experts, the dengue virus has four variants (Den-1 to 4), each of which is further subdivided into distinct genotypes. Den-2, which consists of six genotypes (Asian/American, Asian I, Asian II, Cosmopolitan, American and sylvatic), is frequently associated with severe dengue infections and epidemics.

The fifth variant DENV-5 has been isolated in October 2013. DENV-5 has been detected during the screening of viral samples taken from a 37-year-old farmer admitted in a hospital in Sarawak state of Malaysia in the year 2007.

Dengue Severity

Among the four, they also said Den-2 and Den-3 variants are more severe.

Dengue serotype 2 (DEN-2) viruses with the potential to cause dengue hemorrhagic fever has been shown to belong to the Southeast (SE) Asian genotype. 

Recovery from infection by one serotype provides heterotypic or cross-immunity to the other serotypes. This is only partial and temporary, lasts only a few months, but homotype immunity is lifelong.

For this reason, a person can be infected with a dengue virus as many as four times in his or her lifetime. Subsequent infections (secondary infection) by other serotypes increase the risk of developing severe dengue. 

However, early detection and immediate hospitalization can help lower the risks significantly.

Delayed hospitalization is one of the major causes for the deteriorating conditions of dengue patients and their deaths

Severity is depended on several factors -- serotyping, genotyping and the sequence of the cross infection.

Dengue Symptoms

Most people with dengue have mild or no symptoms and will get better in 1–2 weeks. Rarely, dengue can be severe and lead to death.  

If symptoms occur, they usually begin 4–10 days after infection and last for 2–7 days. Symptoms may include:

• high fever (40°C/104°F)
• severe headache
• pain behind the eyes
• muscle and joint pains
• nausea
• vomiting
• swollen glands
• rash. 

Individuals who are infected for the second time are at greater risk of severe dengue.

Severe dengue symptoms often come after the fever has gone away:

• severe abdominal pain
• persistent vomiting
• rapid breathing
• bleeding gums or nose 
• fatigue
• restlessness
• blood in vomit or stool
• being very thirsty
• pale and cold skin
• feeling weak.

People with these severe symptoms should get care right away. 

After recovery, people who have had dengue may feel tired for several weeks.

Children, Pregnant women and patients suffering from cancer or heart, kidney, and liver complications have to be taken under special supervision.