Dengue Fever
Over view
Dengue fever is a viral infection caused by the dengue virus (DENV), which is transmitted to humans through the bite of an infected Aedes mosquito (primarily Aedes aegypti). It is a common disease in tropical and subtropical regions worldwide and can lead to severe complications, including dengue hemorrhagic fever and dengue shock syndrome.
Causes
Dengue fever is caused by four distinct serotypes of the dengue virus (DEN-1, DEN-2, DEN-3, and DEN-4). It is transmitted primarily through the bite of an Aedes mosquito, which is most active during early morning and late afternoon. The virus is present in the blood of an infected person and can be passed to a mosquito when it bites the individual. The mosquito then carries the virus and transmits it to another person through its bites.
Symptoms
The incubation period for dengue is typically 4 to 10 days after being bitten by an infected mosquito. Symptoms can vary in severity, but common symptoms include:
- High fever: Sudden onset of high fever (often 104°F/40°C).
- Severe headache: Especially in the forehead region.
- Pain behind the eyes.
- Joint and muscle pain (often described as “breakbone fever” due to the intensity of pain).
- Rash: A characteristic rash that may appear a few days after the fever starts (sometimes it can be petechial, a red rash with small blood spots).
- Fatigue and weakness: Feeling extremely tired or weak, which can last for weeks after the fever subsides.
- Nausea and vomiting.
- Loss of appetite.
- Mild bleeding: Such as nosebleeds, gum bleeding, or easy bruising.
Severe Dengue (Dengue Hemorrhagic Fever)
In some cases, dengue can develop into a more severe form known as dengue hemorrhagic fever (DHF), which is marked by:
- Severe bleeding (nosebleeds, gum bleeding, or internal bleeding).
- Plasma leakage: Leading to shock (a drop in blood pressure) and organ failure.
- Abdominal pain and tenderness.
- Persistent vomiting.
- Cold, clammy skin and rapid breathing.
Dengue shock syndrome (DSS) is a life-threatening condition that can result from severe dengue.
Diagnosis
To confirm a diagnosis of dengue, doctors may perform the following tests:
Blood Tests:
- PCR test (Polymerase Chain Reaction): Can detect the virus in the early stages.
- Serology tests: To detect antibodies to the dengue virus (IgM and IgG) that the body produces in response to the infection.
- Complete blood count (CBC): To monitor platelet levels and other signs of complications, such as low white blood cell count and hematocrit.
Clinical Evaluation:
- Doctors assess symptoms, especially in regions with known dengue outbreaks.
- Physical examination helps differentiate dengue from other illnesses.
Treatment
There is no specific antiviral treatment for dengue. Management is mainly supportive and focuses on reducing symptoms and preventing complications:
Hydration:
- Oral rehydration solutions (ORS): To prevent dehydration due to fever and vomiting.
- Intravenous fluids: In severe cases or when oral hydration is not possible.
Fever and Pain Management:
- Paracetamol (acetaminophen): To reduce fever and pain (avoid aspirin, as it can worsen bleeding).
- Anti-inflammatory medications may be used in some cases, but only under medical supervision.
Monitoring:
- Blood tests to monitor platelet count and hematocrit levels.
- Close monitoring for signs of complications (e.g., shock, bleeding, or organ failure) in severe cases.
Hospitalization:
- Severe cases of dengue (DHF or DSS) may require hospitalization for intensive care, blood transfusions, and electrolyte management.
Prevention of Dengue Fever
There is currently no vaccine available for widespread use to prevent dengue, but vaccines like Dengvaxia are used in some countries, particularly for individuals who have had a prior dengue infection. Prevention primarily focuses on avoiding mosquito bites and reducing mosquito breeding grounds:
Mosquito Control:
- Eliminate mosquito breeding sites by removing standing water in containers, tires, and flower pots where mosquitoes lay eggs.
- Larvicides can be used in water bodies to kill mosquito larvae.
Personal Protection:
- Insect repellents: Use DEET, picaridin, or oil of lemon eucalyptus on exposed skin.
- Mosquito nets and screens: Use mosquito nets while sleeping, especially in areas with a high risk of dengue.
- Wear protective clothing: Long-sleeved shirts and pants, especially during peak mosquito activity times (early morning and late afternoon).
Vector Control Programs:
- Governments in affected areas often undertake spraying programs to control the mosquito population.
Conclusion
Dengue fever is a potentially serious viral infection that requires prompt diagnosis and supportive treatment. While most cases can be managed with hydration and symptom relief, severe forms of the disease may require hospitalization. The key to controlling dengue is preventing mosquito bites and reducing breeding grounds for the mosquitoes that transmit the virus.