All about dengue: A guide to navigate through the viral disease

According to WHO about half of the world's population is at risk of dengue, with an estimated 100-400 million infections occurring each year.

BySouth First Desk

Published Jun 30, 2024 | 2:58 AM Updated Jul 09, 2024 | 12:37 PM

Rise of dengue cases in Karnataka

Amidst the torrential monsoon rains, southern states like Telangana and Karnataka are battling a surge in dengue cases, with over a thousand infections already reported.

As rainwater pools in urban nooks and crannies, it’s not just flooding streets but also bringing the dreaded dengue virus to doorsteps.

While the mosquito-borne viral infection usually causes flu-like illness, occasionally it also develops into a potentially lethal complication called severe dengue or dengue hemorrhagic fever.

Amid the surge in cases, South First brings you a know-it-all guide to navigate through the illness.

A viral infection transmitted to humans through the bite of infected Aedes mosquitoes, dengue is found in tropical and sub-tropical climates, mostly in urban and semi-urban areas.

According to World Health Organisation about half of the world’s population is at risk of dengue, with an estimated 100-400 million (10-40 crore) infections occurring yearly.

Most dengue infections are asymptomatic or produce only mild illness, but the virus can occasionally cause more severe, life-threatening cases. It is caused by the dengue virus (DENV), which has four distinct serotypes (DENV-1, DENV-2, DENV-3, and DENV-4).

Also Read: As Telangana reports 886 cases, here’s what you can do

How do humans get infected?

Degue virus infection.

While the infection is caused primarily by mosquito bites, it can be transmitted through various ways.

  • Mosquito bite: Dengue is primarily transmitted through the bites of infected Aedes mosquitoes, such as Aedes aegypti and Aedes albopictus.
  • Virus transmission: When an infected mosquito bites a person, it injects the dengue virus into the person’s bloodstream.
  • Cellular infection: The virus targets and infects nearby skin cells called keratinocytes and immune cells like Langerhans cells, which then transport the virus to the lymph nodes.
  • Spread and replication: Inside the body, the dengue virus replicates, spreading throughout the bloodstream and causing symptoms characteristic of dengue fever.
  • Immune response: The immune system reacts by producing interferons and antibodies to combat the infection.
  • Antibody-dependent enhancement: During a second infection with a different dengue virus strain, existing antibodies can enhance viral entry into cells, potentially worsening the illness.
  • Other modes of transmission: Dengue can rarely be transmitted from a pregnant woman to her fetus and may also be transmissible through sexual contact, blood transfusions, and organ transplants.

Breeding season: A perfect storm for mosquito-borne diseases

1. Ideal conditions for microorganisms

High moisture content in the air during the monsoon season creates an environment where harmful microorganisms thrive, increasing the transmission of diseases through mosquitoes, water, air, and contaminated food.

2. Mosquito breeding habits

  • Species: Aedes aegypti and Anopheles mosquitoes, known for transmitting dengue and malaria, lay their eggs in stagnant water.
  • Breeding sites: Heavy rain leads to water accumulation in containers, puddles, clogged drains, and other areas, providing perfect breeding grounds for mosquitoes.

3. Extended lifespan and increased activity

  • High Humidity: The weather conditions extend the lifespan of mosquitoes, giving them more time to breed and spread diseases.
  • Increased feeding: Mosquitoes are more active and feed more frequently in humid conditions, raising the likelihood of disease transmission.

4. Indoor risks

During the monsoon season, people often spend more time indoors, mistakenly believing they are safe from mosquito bites. However, mosquitoes can breed unnoticed in domestic containers, increasing the risk of indoor bites.

5. Waste management issues

Heavy rains can disrupt proper waste management, leading to more containers and debris that collect water, becoming mosquito breeding sites.

By understanding these factors, individuals and communities can take preventive measures to reduce the risk of mosquito-borne diseases during the breeding season.

Also Read: Bengaluru sees sharp rise in dengue cases in 10 days

Symptoms

Symptoms of dengue fever.

Dengue symptoms can vary from mild to severe. Here are the main symptoms to look out for:

Mild Dengue Fever

  • High fever: Sudden onset of high fever, often reaching up to 104°F (40°C).
  • Severe headache: Intense pain in the head, especially behind the eyes.
  • Pain: Muscle and joint pain, often referred to as “breakbone fever” because it can feel like your bones are breaking.
  • Nausea and vomiting: Feeling sick to your stomach and possibly vomiting.
  • Rash: A red rash that can appear a few days after the fever starts.
  • Fatigue: Feeling very tired and weak.
  • Mild bleeding: Such as nosebleeds, gum bleeding, or easy bruising

Severe dengue (dengue hemorrhagic fever/dengue shock syndrome)

Severe dengue is more serious and can be life-threatening. Symptoms of severe dengue usually develop after the initial mild symptoms. Watch for these warning signs:

  • Severe abdominal pain: Intense pain in the stomach area.
  • Persistent vomiting: Vomiting frequently and not able to keep fluids down.
  • Bleeding: Severe bleeding from the nose, gums, or under the skin, causing bruising.
  • Blood in vomit or stool: Vomit that looks like coffee grounds or stools that are black and tarry.
  • Difficulty breathing: Trouble breathing or rapid breathing.
  • Extreme fatigue: Feeling very weak, tired, and restless.
  • Dizziness or fainting: Feeling dizzy, lightheaded, or fainting due to low blood pressure, or can be a sign of severe dehydration or shock.
  • Fluid accumulation: Swelling of the body or belly due to fluid leaking from blood vessels.

Dengue vs other viral fevers

Dengue vs other viral infections.

Differentiating between dengue and other viral fevers can be challenging because many viral infections share similar symptoms, such as fever, headache, and muscle pain.

However, certain characteristics can help distinguish dengue from other viral fevers. Here are some key differences:

Dengue fever

  • High fever: Sudden onset of high fever (up to 104°F or 40°C).
  • Severe headache: Especially behind the eyes.
  • Joint and muscle pain: Often severe, giving it the nickname “breakbone fever.”
  • Rash: A characteristic rash may appear a few days after the fever starts.
  • Bleeding: Mild bleeding such as nosebleeds, gum bleeding, or easy bruising.
  • Nausea and vomiting: Common.
  • Severe cases: Severe abdominal pain, persistent vomiting, severe bleeding, and difficulty breathing (indicative of severe dengue).

Influenza (Flu)

  • Fever: Sudden onset, but usually not as high as dengue.
  • Headache: Common but not as severe as in dengue.
  • Muscle aches: Common, but usually less severe than in dengue.
  • Cough and sore throat: Prominent symptoms, unlike dengue.
  • Runny or stuffy nose: Common, whereas rare in dengue.
  • Fatigue: Often significant and can last for weeks.

Chikungunya

Also caused by mosquito bites, here are the prominent symptoms of Chickungunya:

  • Fever: Sudden onset.
  • Severe Joint Pain: Prominent, can be more intense and lasts longer than dengue.
  • Rash: Possible, similar to dengue.
  • Headache, muscle pain, nausea: Common.

COVID-19:

  • Fever: Common, but not always very high.
  • Cough: Dry cough is a prominent symptom.
  • Shortness of breath: This can be significant, especially in severe cases.
  • Loss of taste or smell: Specific to COVID-19.
  • Muscle aches, and fatigue: Common, but usually not as severe as in dengue.

Diagnostic tests

While symptoms can provide clues, diagnostic tests are essential to confirm the specific cause of the fever:

  • NS1 antigen test: Detects dengue virus early in the infection.
  • IgM and IgG antibody tests: Detect antibodies against the dengue virus.
  • PCR test: Detects the genetic material of the dengue virus.

Timing of the test

It’s important to get tested for dengue if you show symptoms suggesting you might be infected, especially if you live in or have recently travelled to an area where dengue is common.

Here’s when to consider getting a dengue test:

Early symptoms (1-3 days): If you experience a sudden onset of high fever (up to 104°F or 40°C), severe headache (especially behind the eyes), joint and muscle pain, rash, nausea, vomiting, or mild bleeding (like nosebleeds or gum bleeding), it’s important to seek medical advice.

Persistent symptoms (4-10 days): If your symptoms persist or worsen, such as continuous high fever, increasing pain, or the appearance of new symptoms like severe abdominal pain, persistent vomiting, severe bleeding, or difficulty breathing, you should get tested immediately.

Specific Situations

High-risk areas: If you live in or have travelled to regions with high rates of dengue transmission, it’s prudent to get tested if you develop any symptoms associated with dengue.

Exposure to dengue: If someone in your household or community has been diagnosed with dengue and you start showing symptoms, it’s important to get tested.

Also Read: Mosquito numbers expected to increase due to climate change

When is hospitalisation required in dengue fever cases? 

Hospitalisation for dengue is needed in cases where the infection becomes severe or if there are warning signs of severe dengue.

Here are the situations that warrant hospitalisation:

Severe dengue (dengue hemorrhagic fever/dengue shock syndrome)

Hospitalisation is essential if a person develops severe dengue, which includes complications such as severe bleeding, organ impairment, or plasma leakage.

The key warning signs include low platelet count along with the severe dengue symptoms listed above in the article.

  • Low platelet count: Blood tests show a significant drop in platelet count, increasing the risk of bleeding.
  • Platelet count below 50,000: This level indicates a higher risk of complications and requires hospital monitoring.

Normal platelet counts range from 1,50,000 to 4,50,000 platelets per microliter of blood. In dengue, a significant drop in platelet count can occur, and monitoring these levels is crucial.

High-risk groups

Certain individuals may need hospitalisation even with moderate symptoms, including:

  • Young children: Infants and young children may be more susceptible to severe symptoms and complications.
  • Elderly: Older adults may have weaker immune systems and are at higher risk for complications.
  • People with pre-existing conditions: Individuals with conditions such as diabetes, heart disease, or other chronic illnesses.
  • Pregnant women: Pregnant women need special care to ensure the health of both mother and baby.

Importance of platelet count in dengue

Platelets, also known as thrombocytes, are small blood cells that play a crucial role in blood clotting and preventing bleeding.

With dengue, the virus can cause a significant drop in platelet count, leading to an increased risk of bleeding and other complications.

How platelets fall in dengue

  • Bone marrow suppression: The dengue virus can infect the bone marrow, which is responsible for producing blood cells, including platelets. This leads to a decrease in the production of platelets.
  • Immune system response: The body’s immune response to the dengue virus can inadvertently attack platelets, further reducing their numbers.
  • Destruction in the bloodstream: The virus can cause increased destruction of platelets in the bloodstream.

Monitoring platelets

Mild thrombocytopenia (1,00,000 – 1,50,000 platelets/microliter)

Symptoms: Usually mild or no symptoms.
Action: Regular monitoring and hydration. Usually managed at home with advice from a healthcare provider.

Moderate thrombocytopenia (50,000 – 1,00,000 platelets/microliter)

Symptoms: Increased risk of bruising and mild bleeding.
Action: Close monitoring by a healthcare provider. Seek medical advice if symptoms worsen.

Severe thrombocytopenia (below 50,000 platelets/microliter)

Symptoms: Higher risk of significant bleeding, such as nosebleeds, gum bleeding, or blood in the urine/stools.
Action: Hospitalisation may be required for close monitoring and supportive care.

Critical thrombocytopenia (below 20,000 platelets/microliter)

Symptoms: High risk of severe bleeding, internal bleeding, and hemorrhagic complications.
Action: Immediate hospitalisation is essential. Intensive monitoring and possibly platelet transfusions are necessary.

Also Read: Kerala, Karnataka top the list of dengue cases in the country

Do alternate treatments work?

The use of alternative treatments such as papaya leaf extract and goat milk for managing dengue has been popular in India. However, the effectiveness and safety of these treatments are still subjects of debate and ongoing research.

Here’s what we know about these alternative treatments:

Papaya leaf extract

Claimed Benefits

Increase in platelet count: Some studies and anecdotal reports suggest that papaya leaf extract can help increase platelet count in dengue patients.
Antioxidant properties: Papaya leaves contain antioxidants, which may help reduce oxidative stress and inflammation.

Scientific evidence

Limited studies: A few small studies and clinical trials have shown positive results regarding the ability of papaya leaf extract to increase platelet count in dengue patients. For example, some studies have reported a significant increase in platelet counts and a reduction in hospital stay duration.

“But are these studies done in a very controlled manner?” questioned Dr Philips, popularly known by his handle TheLiverDoc on Twitter.

He added, “A decrease in platelet count may be attributed to infections such as dengue fever or malaria, as well as chronic liver diseases that endure over-extended periods. Additionally, immune-mediated thrombocytopenia can occur, wherein the immune cells target and destroy platelets, leading to a decline in platelet counts. As a result, the potential causes for low platelet count are diverse and varied.”

“There is no evidence that papaya leaf extract improves survival in dengue fever cases. The drop in platelet count is almost invariably reversible, temporary, and without complications,” Dr Rajeev Jayadevan, convener, scientific committee and past president of the Indian Medical Association (Kochi Chapter) explained in past to South First.

Goat Milk

Claimed benefits

Nutritional support: Goat milk is rich in nutrients, including proteins, vitamins, and minerals, which can support general health and recovery.
Digestibility: It is easier to digest compared to cow’s milk and might be better tolerated by some people.

Scientific evidence

Lack of specific evidence: There is no substantial scientific evidence that specifically supports the use of goat milk to treat or manage dengue symptoms or increase platelet count.

Also Read: As companies get dengue vaccine trial nod, scientists are sceptical

Difference in symptoms

The symptoms of dengue fever can differ somewhat between children/adolescents and adults:

Fever and rash

  • Children often have a higher fever compared to adults, sometimes reaching 104°F or higher.
  • A rash also is more common in children, appearing as red spots or bruises on the skin.

Pain and discomfort

  • Severe bone, joint and muscle pain is less common in children compared to adults, who may experience “breakbone fever”.
  • Headaches and eye pain are still common in children but may be harder for them to describe.

Gastrointestinal symptoms

  • Nausea, vomiting and abdominal pain are seen in both children and adults with dengue.
  • Bleeding from the nose, gums or in vomit/stool is more common in severe dengue cases, especially in children.

Severe dengue

  • Children under 15 are at higher risk of developing severe dengue compared to adults.
  • Severe dengue is a medical emergency in children, requiring immediate hospitalization for IV fluids and close monitoring.

Other differences

  • Infants and young children may be irritable, lethargic and have poor appetite.
  • Older children and adolescents have hospitalisation rates similar to adults with dengue

Also Read: First-time dengue infections can be as severe as later ones, reveals study

Prevention and treatment

Prevention of dengue should focus on reducing mosquito exposure and managing symptoms.

Here’s a comprehensive overview:

Prevention

Mosquito control

  • Eliminate breeding sites: Remove stagnant water from containers, flower pots, and gutters where mosquitoes breed.
  • Use mosquito repellents: Apply mosquito repellent containing DEET, picaridin, or oil of lemon eucalyptus on exposed skin.
  • Wear protective clothing: Long-sleeved shirts, long pants, socks, and shoes can help reduce mosquito bites.
  • Use mosquito nets: Especially during sleep, use nets treated with insecticide if sleeping outdoors or in areas with open windows.

Community measures

  • Vector control: Public health measures to reduce mosquito populations, should include spraying insecticides and environmental management.
  • Health education: Raise awareness about dengue prevention measures in communities and schools.

Travel precautions

If travelling to areas with known dengue outbreaks, take extra precautions such as using mosquito nets, wearing protective clothing, and using repellents.

Treatment

Medical care

  • Fluid replacement: Drink plenty of fluids, preferably oral rehydration solutions, to prevent dehydration. Intravenous fluids may be necessary in severe cases.
  • Pain relief: Use acetaminophen (paracetamol) to reduce fever and pain. Avoid NSAIDs (Non-steroidal anti-inflammatory drugs) like aspirin and ibuprofen, which can increase the risk of bleeding.
  • Rest: Get plenty of rest to support recovery and manage fatigue.

Monitoring

  • Platelet count: Regular monitoring of platelet levels to detect any drops that may indicate severe dengue.
  • Symptom management: Manage symptoms such as nausea, vomiting, and rash as they appear.

Research and development

Vaccines: Several dengue vaccines are under development and some are approved in certain countries. Vaccination can play a crucial role in preventing dengue infections.

Also Read: WHO prequalifies Takeda’s dengue vaccine

(Edited by Sumavarsha Kandula)

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