Dengue Virus

‍Introduction

As the outbreaks of Dengue fever increase in India, one state after another getting affected, it is very essential to know more about this disease and prevalence, any change in the viral strain, severity of the disease pattern, early detection of the virus and early management of the disease resulting in good recovery. 

Population growth, rapid urbanization, increase in international travel from endemic areas and global warming are playing a major role in disease spread. Measures should be taken to control the aforementioned causes to prevent disease spread and reduce epidemic flare up.

‍What is dengue ?

• Dengue is the most rapidly spreading arboviral disease, these are members of the genus Flavivirus, within the family Flaviviridae.
• Dengue is a major public health problem throughout tropical and subtropical regions of the world. Many people infected with dengue have no symptoms. But for those who do, the most common symptoms are high fever, headache, body aches, nausea, and rash. Most will get better in 1–2 weeks. Some people develop severe dengue and may need hospitalisation. In severe cases, dengue can be fatal. 
• You can lower your risk of dengue by avoiding mosquito bites especially during the day. Dengue is treated by symptomatic management, as there is no specific treatment currently

‍Epidemiology 

Dengue is believed to infect 50 to 100 million people worldwide in a year. The mortality is 1-5% without treatment and less than 1% with treatment. The incidence of dengue has increased 30 fold between 1960 and 2010. The geographical distribution is around the equator mainly affecting Asia and pacific regions.

In India, First outbreak was reported during 1963 in Kolkata. The next major outbreak of Dengue/Dengue Hemorrhagic Fever was reported in Delhi and neighboring states in 1996. Data for the last 5 years reveal the maximum number of cases reported in 2023 (289235).

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‍Transmission

The viruses are transmitted to humans by the bite of an infected mosquito, Aedes Aegypti but the 2001 outbreak in Hawaii was transmitted by Aedes Albopictus. There are 4 dengue virus serotypes (DENV-1, DENV-2, DENV-3 and DENV-4). Dengue virus is a RNA virus of the family flaviviridae; they are otherwise called arboviruses.

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Humans are the primary host for dengue viruses & transmitted by Aedes mosquitoes. A mosquito that takes a blood meal from an infected person becomes infected with a virus. In 8 to 10 days, the virus spreads to tissues like salivary glands from the gut of the mosquito. The virus seems to have no detrimental effect on the mosquito. Aedes mosquitoes live in close proximity to humans. Dengue may also get transmitted via infected blood products and through organ donation. Vertical transmission from mother to child can also occur during pregnancy

Symptoms of Dengue

Dengue fever presents a spectrum of symptoms. Early recognition of these symptoms is crucial for effective management and treatment. Here are the primary symptoms and signs to look for:

• High fever
• Severe headache
• Pain in muscles, joints, and bones
• Rash
• Mild bleeding (nosebleeds, gum bleeding, easy bruising)
• Fatigue and weakness
• Nausea and vomiting
• Severe abdominal pain
• Persistent vomiting (may include blood)
• Severe bleeding (nose, gums, under skin)
• Rapid breathing
• Organ impairment (liver enlargement, decreased platelets)
• Shock (low blood pressure, cold extremities, weak pulse, restlessness)

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Warning Signs of Severe Dengue
If someone has dengue and starts showing any of the following warning signs, they should seek immediate medical attention as these can indicate the development of severe dengue:

• Severe abdominal pain
• Persistent vomiting
• Rapid breathing
• Bleeding gums
• Fatigue and restlessness
• Blood in vomit or stool
• Cold or clammy skin

Test for dengue‍

Diagnosing dengue involves a combination of Clinical and Laboratory tests to confirm the presence of dengue virus and its antibodies. Following are the common diagnostic  tests for the dengue virus.

• ELISA based NS1 antigen tests
• PCR (Polymerase chain reaction)
• IgM, IgG antibody tests.
• Complete Blood Count (CBC)
  Leukopenia: Low white blood cell count.
  Thrombocytopenia: Low platelet count, common in dengue and indicates severity.
  Hematocrit: Elevated levels may suggest plasma leakage, a sign of severe dengue.
• Liver Function Tests (LFTs): Assess liver function, as dengue can affect the liver.

Diagnostic Approach:

• Early Stage (First Week): NS1 antigen test and PCR are most effective.
• Later Stage (After First Week): IgM and IgG antibody tests help in confirming the diagnosis when the virus may no longer be detectable by NS1 or PCR.
• Monitoring: CBC and LFTs are used to monitor disease progression and detect complications.

If you test positive for dengue, it's essential to consult a healthcare provider for evaluation and guidance, follow medical advice, and maintain rest and hydration. Avoid taking self medications. Monitor for warning signs of severe dengue and seek immediate medical attention if they occur. To prevent further transmission, protect yourself from mosquito bites. In severe cases, hospitalization may be necessary for close monitoring and supportive care. Finally, ensure follow-up with your healthcare provider post-recovery.

How can we protect ourselves from Dengue

The best way to prevent the disease is to prevent bites by infected mosquitoes, particularly if you are living in or traveling to a tropical area. This involves protecting yourself and making efforts to keep the mosquito population down.

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To reduce the mosquito population, get rid of places where mosquitoes can breed. These include old tires, cans, or flower pots that collect rain. Regularly change the water in outdoor bird baths and pets' water dishes.

If someone in your home gets dengue fever, be especially vigilant about efforts to protect yourself and other family members from mosquitoes. Mosquitoes that bite the infected family member could spread the infection to others in your home.