Decoding dengue

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This is an article from our “Doctor’s Corner” series, brought to you by Samitivej Hospital. Make sure to read the entire series!

June is usually low season for tourism in Thailand since the rains keep most tourists away. Some intrepid travelers may venture out to test river rapids and more. One particular visitor, however, spells serious trouble for the people of Thailand. The Aedes aegypti mosquito, responsible for transmitting dengue, comes out to play in this season. With news agencies indicating the possibility of the largest-ever dengue epidemic in Thailand this year, we subject the disease to close scrutiny, analyzing symptoms and preventive measures.

Dengue fever

Lethal bite
When a female Aedes aegypti mosquito bites an infected human, the dengue virus enters the mosquito’s bloodstream, infecting it for life. When such a mosquito next feeds on a human, the virus is transferred to the human. Unlike other mosquitoes that bite and feed off one person until they are full, the Aedes aegypti bites multiple people to feed, thus hastening the spread of the disease.

Dr Krirk Asavametha, specializes in Internal Medicine–Infectious Diseases at the Samitivej Sukhumvit Hospital. He notes, “Aedes is an urban mosquito and lives in clean water, such as that in flower vases, car tires, plates under potted plants, etc. It bites in the day.” If detected in time and treated adequately, death due to dengue reportedly occurs in less than 1% cases. However, severe dengue, also known as dengue hemorrhagic fever is reported to result in death in 26% of cases.

Signals to watch for
The symptoms of dengue might appear only 4–7 days after being bitten by the mosquito. Once symptoms appear, they could last for 2–7 days. Symptoms usually include sudden-onset high fever (40°C/ 104°F), severe headache with pain behind the eyes, muscle and joint pains, decreased appetite, nausea and vomiting, swollen glands, measles-like rashes (in 50-80% cases), and in some cases, mild bleeding (nose bleed, bleeding gums, or easy bruising).

Dr Asavametha points out, “Symptoms are the same in adults, children, and even pregnant women. Kids may have a hard time explaining the symptoms, so diagnosis is more challenging. A flushed face is a clue to diagnosing dengue; the face looks redder than in the case of a fever. Severe body ache is also an indication; dengue was earlier called breakbone fever. People also develop a rash. There are 3 kinds of rashes. In the first few days, we see a viral rash, which is not very different from other rashes. When platelet count drops, bleeding spots appear on the skin. In the last days of the illness, a convalescent rash appears; some people develop itching before it comes on. There is also nausea, vomiting, and diarrhea, which could lead to misdiagnosis. A sore throat and fever could be diagnosed as tonsillitis. Thus, diagnosis can be tricky. Cold or tonsillitis and stomach infection can also present like dengue fever.” These symptoms can worsen in the case of dengue hemorrhagic fever and could also include fluid accumulation in the chest and stomach and organ dysfunction. Dengue can be life-threatening in people suffering from diabetes and asthma or with weakened immune systems. Others at risk include those who have been infected once and have recovered. There are four types of viruses that cause dengue. If a person is infected by one and subsequently recovers, he or she gains immunity to the virus. However, infection by another virus thereafter could cause dengue hemorrhagic fever.

Dengue Data

  • Once restricted to the tropical regions in Southeast Asia, dengue has now been reported in parts of China, Latin and North America, and even Europe. (WHO)
  • As of June 12, Thailand had seen more than 40 deaths and almost 40,000 cases of dengue fever reported in 2013. (Irin News)
  • Nearly 75% of the dengue cases reported worldwide are in the Asia-Pacific Region. Globally, dengue deaths amount to 20,000 each year. (WHO)
  • World Health Organization (WHO) and the Association of Southeast Asian Nations (ASEAN) observed 15 June 2012 as ASEAN Dengue Day. (WHO)

It’s all about timing
Doctors point out that there is no specific treatment or vaccination for dengue. In fact, oral hydration at home could be enough to treat a mild case. However, if doctors detect symptoms of dengue hemorrhagic fever, hospitalization is usually recommended. Early detection is the key to preventing dengue from degenerating into a severe case. Dr Asavametha warns, “Fever, headache, body ache, if you have these symptoms seek medical support. Hydration is very important. People can go into shock if dengue is not detected and treated early. If they come into the hospital late or too dehydrated, then it becomes difficult to treat them. So I’d advise drinking water, forcing yourself to drink water actually. In case of children, this is very important.”

In the case of dengue hemorrhagic fever, specific symptoms may also be treated: blood transfusion for bleeding problems, intravenous (IV) fluids and electrolytes for rehydration or electrolyte imbalances, and oxygen therapy for low blood oxygen. Invasive procedures are avoided since easy bleeding is a symptom. Dr Asavametha has a message for those self medicating, “Local people who have a little bit knowledge, tend to take tablets themselves. If you self medicate, take paracetamol, but avoid anti-inflammatory tablets like ibuprofen and others in the same group. There is a higher risk of bleeding with such tablets. If the fever persists for more than a day or two or if you get tired, seek medical attention.”

Pregnant women can take heart in Dr Asavametha’s pronouncement that dengue is rarely harmful to the fetus.

Prevention is the best medicine
Since there is no specific treatment for dengue, prevention becomes critical. Travel advisories ask tourists to use mosquito repellents. We wondered if local people, including pregnant women and children, could do so as well. Dr Asavametha explains, “Everyone can use repellent. You can use a chemical agent that is called ‘Sai-ya-bet’ in Thai. Its technical name is ‘temefos’ and its common name is ‘Abate Sand Granules’.” He adds, “A vaccine is due to come out within the next two years, but it may only be 70% effective. It is more important to keep the neighborhood clean to prevent dengue or, if someone has already contracted dengue, control its spread.”

It is vital to tackle mosquito breeding grounds. Water must not be allowed to collect, so flower vases and plates under pots and vessels under cooling units must be emptied every day; gutters must be kept clean; soil in pots must be loosened frequently so that water does not collect on the surface; and coconut shells, old tires and any such items where rainwater can collect must be disposed. Using mosquito nets and wearing clothing that covers as much of the body as possible will also help prevent bites. If detected in time, dengue is easy to treat but if not, it could prove fatal. It makes sense, therefore, for everyone to do what they can to make sure this blood-sucking purveyor of death is denied a foothold near their homes.

Looking for a doctor for your child’s health and disease questions? We recommend:
Kirk AsavamethaKirk Asavametha, M.D.
Internal Medicine – Infectious Disease, Samitivej Hospital
Questions about your pregnancy, child birth or life with an infant? Ask the Doctor!

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