Dengue Haemorrhagic Fever

Dengue fever is caused by the virus transmitted by the Aedes aegypti mosquito.

The Aedes mosquito is a small, dark mosquito with white bands on its legs and a silver-white pattern of scales on its body. They are commonly found in human living spaces. These mosquitoes breed easily by laying eggs on the walls of any containers with water in the surroundings. The mosquito is a daytime feeder, and its peak biting periods are early in the morning and in the evening before dusk. The bite appears as an itchy, puffy, white and reddish bump a few minutes after the bite.

Preventing or reducing the risk of dengue fever in children

As these mosquitoes are commonly present in our daily surroundings, children may be exposed to them and get bitten as they go about their daily activities both indoors and outdoors. The following precautions can be taken to minimise your child’s chances of being bitten by an infected Aedes mosquito:

1. Use screens on doors and windows and keep unscreened openings shut
2. Limit the amount of time spent outside during the day, especially in the hours around dawn and dusk, when mosquitoes are most active
3. Have children wear long-sleeved shirts, long pants, shoes and socks when they go outside
4. Use insect repellent as directed on your child. Opt for a repellent with DEET or oil of lemon eucalyptus
5. Use mosquito netting over beds
6. Avoid places where there have been reported cases of dengue infections

When the Aedes mosquito bites a person who has the dengue virus in his or her blood, the mosquito becomes infected with the dengue virus. The virus spreads through the mosquito’s body over a period of 8 – 12 days, after which the infected mosquito can transmit the virus to other people by biting them. Infected mosquitoes can continue transmitting the dengue virus to people for the rest of their life spans, which is generally 3 – 4 weeks. Only female mosquitoes bite humans as they require the proteins from blood to produce eggs.

Female Aedes mosquitoes commonly lay eggs on the inner walls of containers that hold water. They do so above the water line and when the containers fill with water, the mosquito larvae hatch from the eggs. Common containers in which eggs develop into adult Aedes mosquitoes include:

• Plants in water, potted plants and bases
• Pet bowls
• Buckets
• Discarded objects that can collect rainwater (eg. bottles, pots and pans, broken appliances)

Here are several steps you can take to prevent Aedes mosquito breeding sites in and around your home:

1. Pour out water from flowerpots and planters and replace with damp sand
2. Turn over containers that cannot be thrown away to prevent them from collecting rainwater
3. Safely dispose of any unused containers and objects that can accumulate water
4. Change the water in pet bowls at least once a week
5. Clean all drains and gutters
6. Keep grass short and weed-free and keep your patio clean

Many children with dengue fever don’t display symptoms. Others have mild symptoms that last between 4 days and 2 weeks after being bitten by an infected mosquito. Typically, symptoms last for 2 – 7 days and are generally mild in younger children and those infected with the disease for the first time.

Common signs and symptoms of dengue fever include:

• Rapid onset of high fever, possibly as high as 40°C
• Pain behind the eyes and in the joints, muscles and/or bones
• Severe headache
• Rash over most of the body
• Mild bleeding from the nose or gums
• Bruises easily

In people with severe dengue fever or dengue haemorrhagic fever, other symptoms develop and worsen shortly after the regular symptoms of dengue fever subside. These symptoms are life threatening and require urgent medical care. Warning symptoms for severe dengue fever include:

• Severe stomach or belly pain, tenderness
• Nausea and vomiting (at least 3 times in 24 hours)
• Bleeding from the nose or gums
• Vomiting blood or blood in the stool
• Respiratory problems like breathing difficulty
• Feeling tired, restless, or irritable

Diagnosing dengue fever may be challenging as it has symptoms that are similar to other viral illnesses. If you suspect that your child may have dengue fever, consult a doctor immediately.

To make a diagnosis, the doctor will examine your child and evaluate his/her symptoms. You are likely to be asked questions about your child’s medical history and places your child has been to recently. Confirmation of the diagnosis is done with a blood test which detects the presence of the virus in a person’s blood sample. To perform the test, a small amount of blood sample will be taken from a vein in the arm. A positive result means infection with the dengue virus while a negative result may either mean your child isn’t infected or testing was done too early in the disease course.

When your child is receiving treatment for dengue fever, he or she may have their platelet levels monitored to ensure they are recovering well and to identify those at risk of progressing to severe dengue fever. A typical person has a platelet count of between 150,000 and 250,000 per microlitre of blood. Most patients with dengue fever will have platelet levels below 100,000 while levels below 20,000 are considered critically low and are likely to require hospital admission for further treatment.

There is no specific antiviral treatment for dengue fever. Mild symptoms can be treated at home. When caring for your sick infant or child at home, control the fever by giving paracetamol as prescribed and sponge your child’s skin with cool water. Give plenty of fluids and watch for signs of dehydration, such as less frequent urination, dry mouth, tongue, or lips, few or no tears when crying, and a sunken soft spot on the head. Contact your child’s paediatrician immediately if you are concerned by any signs or symptoms your child shows.

Most cases of dengue fever go away within a week or two. As the fever goes away, watch out for warning signs for severe dengue fever, such as stomach pain, vomiting, bleeding from the nose or gums, and feelings of tiredness, restlessness, or irritability. Seek immediate medical care if you notice any of these signs.

Treatment of severe dengue fever at the hospital involves delivery of intravenous fluids and salts to replace the fluids lost through vomiting or diarrhoea. In rare cases, doctors may have to perform a blood transfusion.

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Children are among those at higher risk of developing the severe form of dengue fever known as dengue haemorrhagic fever. Complications from severe dengue haemorrhagic fever may include the following:

• Seizures
• Brain damage
• Blood clots
• Damage to the liver and lungs
• Heart damage
• Dengue shock syndrome

The long-term outcome for dengue haemorrhagic fever depends on how early the condition is detected and care is given. Seeking prompt treatment when you notice signs and symptoms of severe disease in your child can help promote speedy recovery and prevent complications.