Better equipped to handle dengue

-- ST ILLUSTRATION: ADAM LEE
-- ST ILLUSTRATION: ADAM LEE

This article was first published on July 17, 2014

After two days of high fever, a 35-year-old regional manager of a business firm went to see his family doctor.

He was supposed to attend an important overseas meeting and wanted to know if he was fit to travel.

However, he had also lost his appetite and was generally feeling down.

Most viral illnesses are non-specific in nature, particularly during the early stages, as in his case.

While almost everyone who has a viral illness would eventually recover, the duration of the illness can differ significantly.

Some may experience discomfort for two or three days, but others can be sick for up to two weeks.

CLOSE MONITORING NEEDED

Dengue fever is a classic example.

The recent rise in the number of dengue cases here is worrying.

There were 898 reported cases in the week ending July 5 - the highest weekly figure recorded in Singapore.

More people are expected to be affected, given that a surge in cases is anticipated during the hot months of September and October.

The good news is, doctors are getting better at handling this illness, especially those in the primary health-care sector.

Dengue typically starts with a sudden onset of fever, aches and pain. Many also experience severe gastrointestinal symptoms, such as a complete loss of appetite, nausea, vomiting, abdominal pain and diarrhoea.

However, these symptoms are not specific to dengue. They could signal other illnesses too.

Therefore, the regional manager did the right thing by approaching his doctor promptly to be checked for dengue fever.

With a confirmed diagnosis of dengue, his doctor was then able to advise him not to travel and to drink enough fluids, as well as get daily reviews of his condition by his physician.

Dengue typically lasts for one to two weeks.

Fever may rage on for three to five days or longer, followed by the "critical" phase when fluid and protein leak from blood vessels.

When this happens, the heart rate accelerates and blood pressure drops.

It is critical for clinicians to monitor their patients closely to look out for signs of deterioration.

In general, most patients will recover from dengue, although some may have very low blood pressure or go into shock due to severe loss of fluid and plasma. Some may also suffer from internal bleeding or organ damage. Without the appropriate interventions, a rare few may even die from dengue.

Diagnosing the illness early gives doctors the ability to start monitoring patients before they progress to critical illness. It also allows patients to pre-plan their overseas itineraries.

RAPID TEST RESULTS

Today, the rapid-test apparatus can be used in a laboratory or in a clinician's office, providing the means of making an early diagnosis.

The test is simple to administer - it requires just three or four drops of blood plus a drop of buffer regent.

Results can be ready in 15 to 30 minutes.

There are four serotypes of dengue viruses circulating in Singapore. Each serotype has the potential to cause a large number of dengue cases and bring about an epidemic.

They are distinct from one another and as each type can cause illness in humans, a single person can, theoretically, experience four different episodes of dengue.

Local research has precipitated a fundamental change in how doctors manage dengue.

There is now ample evidence suggesting that the illness is likely to be more severe when you get it the second time around.

With this, doctors are now better able to identify those who stand a higher risk of becoming very ill.

MORE RISKY IN ELDERLY

Even so, the increasing spread of dengue among older people presents many challenges.

In one case, a 60-year-old man who has hypertension, ischaemic heart disease (where the heart does not get enough blood due to narrowed arteries), mild stroke and high cholesterol was diagnosed with dengue fever.

His doctors, who anticipated that he would be at risk of bleeding and unstable blood pressure, grappled with the difficult issue of whether to stop his aspirin and anti-hypertensive medication.

Aspirin or anti-platelet agents help to thin the blood to prevent blockage of blood vessels. However, dengue may cause a drop in platelet count, so people on this medication face a higher risk of bleeding.

Many older people also have diabetes and renal diseases.

These conditions require them to restrict their fluid intake. This makes dengue care challenging as adequate hydration is important.

The dynamic changes of heart rate and blood pressure which affect those with dengue add another level of complexity to their treatment.

More studies are needed to explore the best management approach for this group of older people.

Not only do they require close observation, in general, they should also be hospitalised early due to the complexity of dealing with their pre-existing medical conditions. They also tend to end up with more severe dengue illness.

The good news is, through years of research and collaboration, there has been a noticeable increase in confidence among primary-care doctors in managing dengue.

Today, proportionately fewer cases are being referred to specialist care.

During the last dengue epidemic which took place between 2004 and 2005, about 70 per cent to 80 per cent of patients were admitted into hospital. This year, the rate is below 20 per cent.

Another encouraging piece of news is the corresponding drop in the number of deaths.

Infectious diseases do not respect geographical boundaries and, similarly, boundaries within the health-care system.

It requires the efforts of all levels of health-care providers to provide the best care to patients.

enquiries@nhg.com.sg

Prof Leo is the director of the Institute of Infectious Diseases and Epidemiology and is also the clinical director at the Communicable Disease Centre. She is a senior consultant at the department of infectious diseases at Tan Tock Seng Hospital, the flagship of the National Healthcare Group, the Regional Health System for Central Singapore.