Dengue Management and Testing - Mr Ang Wei Neng

8 July 2013

Question No. 542

Name of Person: Mr Ang Wei Neng

Question

To ask the Minister for Health (a) whether the Ministry is satisfied with how Tan Tock Seng Hospital handled the two victims who died from dengue in May/June 2013; (b) how can Tan Tock Seng Hospital and other public hospitals learn from the episode and improve processes to better treat patients infected by dengue; and (c) how can the Ministry work with the various stakeholders to lower the cost of a dengue test substantially especially those conducted by private clinics.

Answer

1        I wish to express once again our deepest condolences to the families of the two Singaporeans who passed away from Dengue Shock Syndrome.

2        The clinical spectrum of dengue ranges from mild or asymptomatic infections to more severe forms of the disease. The vast majority of dengue patients have mild, self-limiting disease. However, a minority of patients develop more serious Dengue Haemorrhagic Fever (DHF) and Dengue Shock Syndrome (DSS), which can result in life-threatening complications.  As of 22 June 2013, MOH has been notified of 10,959 dengue cases. Of these, 46 (or 0.4%) had the more severe DHF.

3        There is currently no specific antiviral medication to treat dengue. The key to managing dengue patients is therefore to ensure that they get sufficient rest and hydration while their body fights the virus, and to closely monitor their clinical status so that additional supportive therapy such as platelet or blood transfusions can be provided if necessary. Unfortunately, despite the best efforts of our doctors, some cases of DHF or DSS will succumb to the disease.

4.       MOH was notified of the first death this year from DSS on 29 May 2013. The deceased presented at Tan Tock Seng Hospital (TTSH) emergency department (ED) on 23 May with fever and flu-like symptoms for one day, and was diagnosed with viral fever with possible early dengue.  He was discharged as he was clinically stable and was keen to go home.  He was advised to have his blood test repeated by a primary care doctor and asked to return to the ED if his symptoms worsened.  He returned to the ED on 24 May but left, at his own request, without seeing the doctor. On 26 May, he visited TTSH ED with complaints of fever, headache and vomiting, and was admitted.  He tested positive for acute dengue infection.  He subsequently developed liver inflammation and confusion and was transferred to the intensive care unit (ICU) on 28 May. However, his condition continued to deteriorate despite maximal supportive therapy, including multiple blood transfusions, and he passed away on 29 May.

5.       The second death from DSS was notified to MOH on 9 Jun.  The deceased, who had a history of diabetes and high blood pressure, presented at TTSH ED on 5 Jun with fever for one day, as well as left leg swelling and redness.  He was clinically stable at the visit. He was diagnosed with cellulitis, discharged with antibiotics, and also advised to be monitored by a primary care provider for possible dengue. He was asked to return to the ED should his symptoms worsen.  He next visited the ED on 7 Jun with weakness of his legs, with worsened swelling and redness of his left leg, and persistent fever.  He was admitted for left leg cellulitis and probable dengue, which was confirmed by laboratory testing. He developed kidney failure and liver inflammation and was subsequently transferred to the ICU on 8 Jun. His condition continued to deteriorate and he passed away on 9 Jun despite maximal treatment. 

6.       MOH sought independent expert opinion on the management of both cases. The experts have advised that the clinical management was consistent with accepted standard clinical practice in both cases.

7.       MOH and our public hospitals continually improve clinical management by sharing and learning good practices.  MOH regularly issues circulars to our doctors and hospitals to provide updates on the dengue situation and reinforce advice about the clinical management of dengue or suspected dengue patients. Doctors are advised to monitor dengue patients closely, and to look out for warning signs and symptoms which may warrant a referral to hospital for further medical evaluation and management. Hospitals are also reminded to ensure that for suspect or confirmed dengue patients who are clinically assessed to not require admission at that point in time, there are outpatient monitoring systems to review them. In addition, hospitals have been informed that suspect and confirmed cases of dengue who return to emergency departments within 24 to 48 hours should be appropriately prioritised at triage.

8.       Doctors usually make a clinical diagnosis of dengue based on an overall assessment of the patients. Dengue tests can be ordered by doctors if deemed appropriate. The dengue tests which are commonly used are those which look for the presence of dengue NS1 antigen and dengue antibodies in the blood. NS1 antigen is a dengue virus protein and is usually present in the blood between day 2 and day 5 of infection, when the patient has a fever and the dengue virus is circulating in the blood. Dengue antibodies are usually detected only 5 to 7 days after the fever has started.  Thus, although dengue tests may help to support the diagnosis of dengue, a test that is done too early in the course of the illness may not give definitive results. For example, a negative dengue test on the first day of fever would not conclusively exclude the possibility of dengue. Dengue testing therefore has to be guided by the doctor’s overall evaluation of the patient’s clinical presentation.

9.       Dengue tests are available in our public hospitals. To facilitate the early diagnosis of dengue during this epidemic, the Ministry has also increased the subsidies for dengue NS1 testing at the emergency departments of public hospitals during the period of the epidemic so that patients will not pay more than $10 per test.  This has already been in place since 17 June.

10.     Many private general practitioner (GP) clinics have existing arrangements for dengue testing, such as by sending samples to laboratories. NEA’s Environmental Health Institute provides dengue NS1 antigen and antibody testing to all GPs and polyclinics at no cost, as part of NEA’s efforts to promote early dengue diagnosis and prevent further transmission of the virus. We will continue to work with the private medical clinics to advise them on how they can access dengue testing services, if they do not already have existing arrangements to carry out such tests.