Dengue Fever

Dengue fever is a significant public health concern, especially in regions with warm and humid climates. It is caused by the dengue virus, transmitted to humans through the bite of an infected Aedes mosquito. The disease can range from mild to severe, and in some cases, can be life-threatening. Understanding the causes, symptoms, and prevention methods is crucial for safeguarding our health and well-being.

What Is Dengue Fever?

Dengue fever is a viral infection transmitted to humans through the bites of infected female Aedes mosquitoes, primarily Aedes aegypti. These mosquitoes typically bite during the day, with peak biting periods in the early morning and late afternoon. When an infected mosquito bites a human, the dengue virus enters the bloodstream and replicates in the body's cells.

The incubation period, or the time between the mosquito bite and the onset of symptoms, is typically 4-10 days. The disease is marked by a sudden onset of high fever. It is often accompanied by headache, eye pain, muscle and joint pain, nausea, vomiting, and skin rash. These symptoms usually last for 2-7 days, after which most people recover without complications. However, in some cases, the disease can progress to a severe form called dengue hemorrhagic fever, which can be life-threatening.

In the initial stages, dengue fever can present non-specific symptoms similar to other viral illnesses. However, some of the characteristic early signs to watch out for include:

• Sudden onset of high fever (40°C/104°F)

• Severe headache, especially behind the eyes

• Intense joint and muscle pain

• Feeling extremely tired and unwell

• Nausea and vomiting

• Skin rash appearing 3 to 4 days after the fever begins

If you experience these symptoms and live in or have recently travelled to an area where dengue fever is prevalent, it's advisable to consult a doctor. Timely diagnosis and supportive treatment can help prevent complications and improve outcomes.

The symptoms of dengue fever usually begin 4 to 10 days after being bitten by an infected mosquito. Typical symptoms include:

• High fever (40°C/104°F)

• Severe headache, often described as pain behind the eyes

• Muscle and joint pain, which can be quite severe

• Nausea and vomiting

• Swollen glands

• Rash that typically appears three to four days after the onset of fever

• Fatigue

In severe cases, dengue fever can progress to a life-threatening condition called severe dengue or dengue haemorrhagic fever. Symptoms of severe dengue can include:

• Severe abdominal discomfort

• Continuous vomiting

• Rapid breathing

• Bleeding from the gums or nose

• Tiredness and agitation

• Blood in vomit or stool

• Pale, cold, or clammy skin

• Feeling weak or lightheaded

It's important to recognise the early signs of dengue fever so that prompt medical attention can be sought if symptoms worsen.

Dengue fever typically progresses through three phases: the febrile phase, the critical phase, and the recovery phase.

1. Febrile Phase:

• This initial stage begins 3-14 days after the mosquito bite and lasts 2-7 days.
• It is marked by a sudden onset of high fever (40°C/104°F), severe headache, pain behind the eyes, muscle and joint pains, and sometimes a skin rash.
• Other symptoms may include nausea, vomiting, and loss of appetite.

2. Critical Phase:

• This phase usually occurs 3-7 days after the onset of symptoms and lasts for 24-48 hours.
• A small proportion of patients (about 5%) may develop severe dengue. It is characterised by severe abdominal discomfort, persistent vomiting, rapid breathing, bleeding gums, fatigue, and restlessness.
• In severe cases, there may be severe bleeding, organ damage, and plasma leakage, leading to dengue shock syndrome and potentially death.
• Warning signs of severe dengue include severe abdominal discomfort, continuous vomiting, rapid breathing, bleeding gums, fatigue, restlessness, and blood in stool or vomit.

3. Recovery Phase:

• This phase usually lasts 2-3 days and is marked by a gradual improvement in symptoms.
• The patient's appetite returns, gastrointestinal symptoms abate, and their general well-being improves.
• However, this phase may be accompanied by severe itching and a slow heart rate.
• Some patients may experience a rash that appears like "islands of white in a sea of red.

It is crucial to monitor patients carefully during the critical phase, as this is when severe dengue can manifest. Timely medical intervention is essential to prevent complications and ensure a full recovery.

Dengue fever is a mosquito-borne viral infection caused by one of the four types of dengue viruses (DENV-1, DENV-2, DENV-3, and DENV-4). The viruses are transmitted to humans through the bite of an infected female Aedes mosquito, primarily the Aedes aegypti species.

When a mosquito bites a person infected with the dengue virus, the virus enters the mosquito's body. After an incubation period of 8-10 days, the infected mosquito can transmit the virus to other humans during subsequent blood meals. The virus cannot spread directly from person to person.

Factors that increase the risk of dengue fever include:

• Living in or travelling to tropical and sub-tropical areas

• The presence of mosquito breeding sites near human habitation

• Lack of effective mosquito control measures

• Absence of immunity to the specific dengue virus type

Several key risk factors are associated with dengue fever, which can be categorised into environmental, behavioural, and demographic aspects.

1. Environmental Risk Factors

• Stagnant water in small puddles, tyres, and ditches around homes, serves as breeding grounds for Aedes mosquitoes.
• The presence of flower pots and open water containers inside homes.
• Uncovered water tanks and poor waste disposal, including old containers and tyres, facilitate mosquito breeding.

2. Behavioural Risk Factors

• Travelling to dengue-endemic regions increases infection risk.
• Low awareness about dengue and its prevention.
• Communities with limited health education and knowledge about dengue transmission and prevention have higher incidence rates.

3. Demographic and Socioeconomic Risk Factors

• Middle social class households show higher dengue cases.
• Crowded living conditions, with more than two occupants per room, increase the risk.
• Unplanned urbanisation, high population density, and poor water storage practices contribute to increased transmission.
• Understanding these risk factors is key to creating effective dengue prevention and control strategies.

Dengue fever can lead to several complications, some of which may be life-threatening if not properly managed. One major concern is severe dengue, which is more likely in individuals with a prior dengue infection. Severe dengue can manifest as hemorrhagic fever or shock syndrome, both of which require urgent medical attention due to their life-threatening nature.

Another complication is maternal transmission, where the virus is passed from a pregnant mother to her baby. This could potentially lead to pre-term birth, low birth weight, or fetal distress. Although rare, dengue fever can also be transmitted through blood products, organ donation, and transfusions, and there have been instances of transovarial transmission within mosquitoes. Prompt diagnosis and appropriate management are essential to prevent these complications and improve the patient's prognosis.

Prevention of dengue fever involves both individual and community-level measures to reduce the risk of infection and control the spread of the disease.

Individual Protective Measures:

• Wear clothes that cover as much of the body as possible, especially during the day when mosquitoes are most active.

• Use mosquito repellents containing DEET, picaridin, or oil of lemon eucalyptus on exposed skin.

• Install screens on windows and doors to prevent mosquitoes from entering the house.

• Use mosquito nets while sleeping, especially if the room is not adequately screened.

Community-Level Measures:

• Eliminate mosquito breeding sites by removing stagnant water from containers, tyres, and other receptacles.

• Regularly clean and cover water storage containers to prevent mosquito breeding.

• Participate in community-based dengue prevention programmes, such as awareness campaigns and clean-up drives.

• Support local health authorities in implementing vector control measures, such as insecticide spraying and larval control.

Diagnosing dengue fever involves both clinical evaluation and laboratory tests. Clinically, doctors assess symptoms such as high fever, severe headache, eye pain, muscle and joint pain, nausea, vomiting, swollen glands, and rash. Laboratory tests play a crucial role, starting with a complete blood count (CBC), which typically reveals low white blood cell and platelet counts. Serological tests, such as IgM and IgG antibody tests, are used to detect antibodies produced in response to the dengue virus.

Viral isolation, though mainly used in research, involves growing the virus from a blood sample. Molecular testing, like polymerase chain reaction (PCR), can detect dengue virus RNA in the blood during early infection. Rapid diagnostic tests are also available, offering quick results, but they may have lower accuracy compared to traditional laboratory methods. Accurate diagnosis is essential for proper management and treatment of dengue fever.

Dengue fever treatment includes:

1. Symptom Management

• Focus on supportive care to manage symptoms, as no specific antiviral treatment exists.
• Acetaminophen (paracetamol) is recommended for controlling fever and relieving pain.
• Avoid NSAIDs like ibuprofen and aspirin due to their anticoagulant properties, which increase bleeding risk.

2. Hydration and Rest

• Staying hydrated is essential; patients should drink plenty of fluids, including electrolyte-rich drinks.
• Rest is critical for managing the illness and supporting recovery.
• Fever can be managed with acetaminophen and tepid sponge baths.

3. Severe Dengue Care

• Hospitalisation is often required for severe cases, with close monitoring in an ICU.
• Prophylactic platelet transfusions are not recommended due to the risk of fluid overload.
• Corticosteroids should be avoided unless treating specific autoimmune complications.

Living with dengue fever requires a comprehensive understanding of recovery, re-infection risks, and preventive measures. While most people recover fully, awareness of the potential for fatigue and avoiding future infections is crucial for long-term health.

1. Recovery Process:

• Recovery from dengue fever is typically complete, with most individuals experiencing no lasting complications.
• However, it is common to feel fatigued for several weeks post-illness, which is a normal part of the healing process and should improve gradually.

2. Risk of Re-Infection:

• There are four different strains of the dengue virus, making it possible to contract dengue more than once.
• Subsequent infections can heighten the risk of severe dengue, so it’s crucial to take preventive measures even if you have had the illness before.

3. Preventive Measures:

To lower the risk of infection, individuals should avoid mosquito bites by:

• Wearing clothing that covers the body.
• Using mosquito nets and window screens.
• Applying mosquito repellents containing DEET, Picaridin, or IR3535.

4. Environmental Management:

Preventing mosquito breeding is essential. This involves:

• Proper disposal of solid waste.
• Removing artificial habitats that can hold water.
• Regularly covering, emptying, and cleaning domestic water storage containers.

5. Vaccination Considerations:

• In some cases, vaccination may be recommended for those who have previously had dengue.
• The dengue vaccine, such as Dengvaxia™, can help reduce the risk of severe dengue in individuals with a history of the disease.
• However, it is not recommended for those who have never had dengue before.

If you suspect dengue fever, seek medical attention promptly. Early diagnosis and management can prevent complications. Key signs include high fever (40°C/104°F) with severe headache, pain behind the eyes, and muscle and joint pain. Nausea, vomiting, swollen glands, or rash also require attention. Severe abdominal discomfort and continuous vomiting warrant a doctor's visit. Cold or clammy skin, along with fatigue or restlessness, should not be ignored.

If you recently traveled to a dengue-endemic area, inform your doctor if you develop flu-like symptoms. This information helps in accurate diagnosis. In severe cases, immediate medical care is essential. Seek help for severe abdominal discomfort, vomiting, rapid breathing, bleeding, or mental status changes. Prompt treatment can be life-saving.