Dengue

Dengue is a mosquito-borne viral infection that has rapidly spread in many parts of the world in recent decades. It is caused by the dengue virus (DENV), which is transmitted by Aedes mosquitoes, particularly Aedes aegypti. It is a significant global health concern, especially in tropical and subtropical regions, where it poses a considerable public health challenge. According to the World Health Organization (WHO), about half of the world’s population is now at risk of the disease, with an estimated 390 million dengue infections occurring each year.

This blog aims to provide a detailed understanding of the disease, including its causes, symptoms, transmission, treatment, and prevention. By the end of this article, readers will have a clearer insight into this potentially deadly disease and the measures that can be taken to control its spread.

What is Dengue?

It is a viral infection caused by the dengue virus, which belongs to the Flavivirus genus. There are four distinct, but closely related, serotypes of the virus: DENV-1, DENV-2, DENV-3, and DENV-4. A person can be infected with dengue up to four times in their lifetime, as infection with one serotype provides immunity only against that particular serotype, not the others. Subsequent infections with a different serotype increase the risk of developing severe dengue, also known as dengue hemorrhagic fever (DHF).

It is primarily transmitted to humans through the bite of an infected Aedes mosquito, which acquires the virus while feeding on the blood of an infected person. The disease is widespread in regions with warm climates and high humidity, such as Southeast Asia, the Pacific Islands, Latin America, and the Caribbean.

Dengue symptoms:

Dengue can manifest in a wide range of symptoms, from mild flu-like symptoms to severe and life-threatening conditions. The symptoms typically begin 4-10 days after the mosquito bite and can last for 2-7 days.

1. Mild Dengue Fever:

The majority cases are mild and may present with the following symptoms:

• High fever (40°C/104°F)
• Severe headache
• Pain behind the eyes
• Muscle and joint pains (often referred to as “breakbone fever”)
• Nausea and vomiting
• Swollen glands
• Rash

These symptoms can be mistaken for other illnesses like influenza or measles, making diagnosis challenging without proper testing.

2. Severe Dengue (Dengue Hemorrhagic Fever or Dengue Shock Syndrome):

It is a more serious form of the disease that can be fatal if not treated promptly. It occurs when the blood vessels become damaged and leaky, leading to bleeding, low platelet count, and plasma leakage. Symptoms of severe dengue include:

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

Severe dengue can lead to shock, organ failure, and death if not managed quickly.

Transmission of Dengue:

It is primarily transmitted through the bite of infected female Aedes mosquitoes, which are most active during the early morning and late afternoon. The Aedes aegypti mosquito is the most common vector, but Aedes albopictus can also transmit the virus. These mosquitoes breed in stagnant water, such as in flower pots, discarded tires, and containers, making urban and semi-urban areas particularly vulnerable to outbreaks.

Human-to-human transmission does not occur directly, but the virus can spread from an infected person to a mosquito, which then infects another person. In rare cases, it can also be transmitted through blood transfusions, organ transplants, and from a pregnant woman to her baby.

Diagnosis of Dengue:

Early diagnosis is crucial for effective management and treatment of the disease. However, diagnosing dengue can be challenging due to the similarity of its symptoms with other viral infections. Several laboratory tests are available to confirm dengue infection:

• NS1 Antigen Test:
  This test detects the non-structural protein 1 (NS1) antigen of the virus and is most effective during the early stages of the infection, usually within the first week.
• RT-PCR Test:
  Reverse transcription-polymerase chain reaction (RT-PCR) is a molecular test that detects the presence of viral RNA in the blood. It is highly specific and sensitive, making it a reliable method for confirming the disease.
• Serological Tests (IgM and IgG):
  These tests detect antibodies produced by the body in response to the virus. IgM antibodies appear during the acute phase of the infection, while IgG antibodies indicate a past infection or secondary dengue infection.

Dengue treatment:

There is no specific antiviral treatment for the disease. Management focuses on supportive care and symptom relief. The key aspects of dengue treatment include:

• Fluid Replacement Therapy:
  Adequate hydration is crucial for patients, especially in severe cases where plasma leakage can lead to dehydration. Oral rehydration solutions (ORS) are recommended for mild cases, while intravenous fluids may be necessary for severe dengue.
• Pain Management:
  Fever and pain associated with the disease can be managed with paracetamol (acetaminophen). Non-steroidal anti-inflammatory drugs (NSAIDs) like aspirin and ibuprofen should be avoided, as they can increase the risk of bleeding.
• Monitoring and Supportive Care:
  Patients with severe dengue require close monitoring in a hospital setting. Healthcare providers monitor vital signs, blood counts, and fluid balance to detect signs of shock or bleeding early.
• Blood Transfusion:
  In cases of severe bleeding or low platelet count, blood transfusions may be necessary to manage hemorrhagic symptoms.

Prevention of Dengue:

Preventing dengue primarily involves controlling the mosquito population and minimizing the risk of mosquito bites. Key strategies include:

• Mosquito Control:
  Eliminating mosquito breeding sites is one of the most effective ways to reduce the spread of the disease. This involves removing standing water from containers, covering water storage tanks, and using insecticides in areas with high mosquito populations.
• Personal Protection:
  Individuals can protect themselves from mosquito bites by using insect repellent, wearing long-sleeved clothing, and sleeping under mosquito nets, especially during peak mosquito activity times.
• Community Education:
  Raising awareness about dengue and educating communities about mosquito control measures can help prevent outbreaks. Public health campaigns play a crucial role in spreading information about dengue prevention.
• Vaccination:
  The Dengvaxia vaccine, developed by Sanofi Pasteur, is currently available for individuals aged 9-45 years who have had a previous dengue infection. The vaccine is not recommended for those who have never been infected with dengue, as it may increase the risk of severe dengue upon subsequent exposure to the virus.

Challenges in controlling the disease:

Despite efforts, several challenges hinder the global fight against this disease. Some of the key challenges include:

• Urbanization and Population Growth:
  Rapid urbanization and population growth in tropical regions have led to increased mosquito breeding sites and higher human-mosquito contact, contributing to the spread of the disease.
• Climate Change:
  Changes in climate patterns, such as increased rainfall and higher temperatures, have expanded the geographic range of Aedes mosquitoes, leading to the spread of dengue to new areas, including temperate regions.
• Inadequate Healthcare Infrastructure:
  In many dengue-endemic countries, healthcare infrastructure is insufficient to manage large outbreaks, leading to higher morbidity and mortality rates.
• Lack of Effective Vaccines and Treatments:
  The limited availability of effective vaccines and the absence of specific antiviral treatments for the disease pose significant challenges in controlling the disease.
• Insecticide Resistance:
  The widespread use of insecticides has led to the development of resistance in mosquito populations, reducing the effectiveness of chemical control measures.

Dengue is a complex and rapidly spreading disease that poses a significant threat to global health. While considerable progress has been made in understanding the virus and controlling its spread, much remains to be done to reduce the burden of the disease. Effective prevention and control strategies, including mosquito control, vaccination, and community education, are essential in the fight against dengue. Additionally, addressing challenges such as urbanization, climate change, and healthcare infrastructure will be crucial in mitigating the impact of this disease in the coming years.

Public health authorities, governments, and individuals must work together to combat dengue and protect vulnerable populations from this potentially deadly virus. Through coordinated efforts, it is possible to reduce the incidence of dengue and move closer to the goal of eliminating the disease as a public health threat.

Remember, if you suspect you have dengue fever or any other medical condition, it is always best to consult a doctor for an accurate diagnosis and appropriate treatment. Stay informed, take precautions and help spread awareness to protect yourself and those around you.

Sparsh Diagnostic Centre can collect blood samples from the comforts of your own home. To organise a test, please call our helpline number 9830117733.

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Additional Reading

• https://www.who.int/news-room/fact-sheets/detail/dengue-and-severe-dengue

Disclaimer:

No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.