Unusual factors in SGH hepatitis C outbreak

An infectious diseases expert assesses the independent review committee's report to highlight what was done well, and the need to empower healthcare workers to do their job better

The independent review committee (IRC) report on the recent outbreak of hepatitis C at the Singapore General Hospital (SGH) has 81 pages of detailed facts, figures, assertions and conclusions. It would be good, first of all, to review what we know about hepatitis C viral outbreaks globally.

Unlike hepatitis A and E, which are spread by contaminated food and water, hepatitis B and C are spread exclusively by blood and body fluids. Hepatitis B is being brought under control globally with successful vaccination programmes in which Singapore was a leader and pioneer. Hepatitis C has no licensed vaccine but, in recent years, there have been a number of drugs which have been remarkably successful in curing the disease. However, these drugs are very expensive and can cost in excess of US$80,000 (S$112,400) for a three-month course.

Patients with acute hepatitis C usually do not have any symptoms at all, although occasionally patients will have jaundice (yellowing of the skin) and other signs of liver disease. As a result, most outbreaks, even in major academic medical centres internationally, were not detected for months.

A rare complication of hepatitis C that was previously reported to occur infrequently in transplant patients (1.5 per cent of kidney transplant patients in one large study), called fibrosing cholestatic hepatitis (FCH), can lead to rapid progression to liver failure and death.


The SGH infection control team's investigation led to the tightening of procedures and the effective end of the hepatitis C outbreak soon after it was recognised. ST PHOTO: KUA CHEE SIONG

Surprisingly, this occurred in many of the transplant patients in the recent SGH outbreak, which probably accelerated its detection and reporting. Dozens of previous hepatitis C outbreaks in hospitals worldwide have almost never resulted in fatalities. This is one of the many unusual features of the SGH outbreak.

Hepatitis C is most efficiently spread through unsafe injection practices, inadequately screened blood transfusions, by sexual contact and by contamination when administering injections. Hepatitis C cannot be spread by casual contact and unless the skin is broken, there is no risk of an individual contracting hepatitis C. It cannot be spread by ordinary interactions or by simply handling objects in an environment where people with hepatitis C live, work or are taken care of.

Hepatitis C is also not even that easily spread through broken skin. When a healthcare worker sustains a sharp injury from a hepatitis C-infected patient, the documented rates of infection range from 0.2 to 5 per cent.

Hepatitis C is rare in the general Singapore population, with less than 0.5 per cent of the population estimated to be positive. However, there are certain groups in Singapore who have much higher infection rates. A study this year of 170 illicit drug users in Singapore found that while none of them was HIV-infected (as most did not share needles), nearly 40 per cent were hepatitis C-positive. This could be because they often shared drug paraphernalia and the hepatitis C virus can survive much longer outside the body than HIV.

A 2006 report stated that 46 per cent of Singapore patients with haemophilia (a blood disorder that requires frequent blood and clotting factor transfusions) and 28 per cent of Singapore patients on haemodialysis ("blood dialysis") were hepatitis C-positive.

In contrast, only 5 per cent of Singapore patients on peritoneal dialysis ("water dialysis") were found to be hepatitis C-positive; this again emphasises the importance of blood and injections in the spread of the virus.

COMPREHENSIVE SURVEILLANCE SYSTEM

Singapore has had a comprehensive surveillance system for hepatitis C for years. All cases of viral hepatitis B and C are required by law under the Infectious Diseases Act to be notified to the Ministry of Health (MOH) within 72 hours.

According to a report published in the local Epidemiology News Bulletin last year, all these notifications are individually reviewed by an MOH public health officer, who decides if the cases meet the current case definition of acute hepatitis C. Cases meeting the definition are then investigated to determine the source of the infection.

According to that report, the rate of acute hepatitis C infection dropped from 10.1 per cent of all viral hepatitis cases notified in the years 2005-2007 to 2.4 per cent in the years 2008-2013. This was due mainly to successful efforts to curtail the illicit injection of subutex (a drug used to treat opiate addiction) by Singaporean substance abusers.

In addition, under the Private Hospitals and Medical Clinics Act (PHMC), all dialysis providers are required to routinely test patients for HIV, hepatitis B and hepatitis C.

The National Organ Transplant Unit of the MOH also does passive surveillance of viral infections after transplantation to ensure that there are no outbreaks such as the tragic cases of dengue in transplantation in 2003.

In addition, the regulations under the PHMC cover serious reportable events, including infections post-transplant. These mandate reporting within two working days.

MOH also routinely keeps track of selected hospital-acquired infections, in particular hospital- acquired methicillin-resistant Staphylococcus aureus (MRSA) infections as a marker of the quality of infection control programmes. It would be interesting to know if the devastating general "infection control lapses" which are being blamed for the SGH hepatitis C outbreak were also reflected in increased MRSA rates in the affected wards.

As the above survey of MOH surveillance measures suggests, an existing system is in place to monitor hospital-acquired infections. However, the implementation of these systems in the different hospitals and healthcare facilities needs to be strengthened and made both practical and effective.

HEP C OUTBREAKS WORLDWIDE

The US Centres for Disease Control and Prevention (CDC) published a report this year in the journal Hepatology of all the outbreaks of hepatitis C reported in developed countries. There were 46 healthcare-associated outbreaks of hepatitis C from 1990 to 2012. Seven were caused by hepatitis C-infected surgeons, seven by incidents in anaesthesia due mainly to reuse of syringes or multi-dose vials, 24 were caused by breaches in infection control (predominantly related to haemodialysis, reuse of syringes, multidose vials or the older spring-loaded blood-sugar testing devices), and eight were deliberate acts of drug diversion by healthcare workers tampering with narcotic solutions.

Tampering occurs when someone with access to controlled drugs (narcotics) injects himself and then re-enters a vial of narcotic drugs using the same syringe or needle. If that person is hepatitis C-infected, there is a high risk that the virus can be spread to patients who are on these powerful painkillers for legitimate reasons.

Alternatively, tampering occurs when an illicit drug user taps a nearby saline solution to "top up" a vial of narcotics after helping himself to some of the drug. The vial will then look like it is still full of the narcotic on visual inspection when, in reality, it may have only half the concentration of the drug.

There are a series of steps which needs to be taken to elucidate which of these is the cause of an outbreak and these are illustrated in Annex A of the Independent Review Committee Report.

They include defining cases, doing a case control study to identify risk factors for infection and testing the hypotheses generated. The one step not listed in the Annex A list that was also not done by the SGH infection control team was a broad sweep to determine the extent of the infection by making a public call for those potentially infected to come forward for testing and treatment.

For some reason, that was delayed and the SGH leadership is now paying the price for that delay.

Its case control study was, however, well done and it showed that patients in the affected wards who were infected were nearly three times more likely than non-infected patients to receive an intravenous fluid injection. This is consistent with other outbreaks in developed countries where contaminated fluids have spread the virus.

SINGLE SOURCE OF OUTBREAK?

Finally, most modern outbreak investigations use DNA/RNA-fingerprinting or molecular epidemiology to link viruses or bacteria isolated from outbreaks.

This is another striking feature of the SGH outbreak - the isolates were almost identical, which strongly suggests a single point source outbreak (such as repeated contamination of saline solutions from the same index case). A general breakdown in hospital hygiene would usually result in a multiplicity of strains reflecting the different viruses present in different patients in the wards or hospital at the time.

The IRC had a difficult job attempting to do a high-profile investigation in a short period of time. It is unclear if the committee had the benefit of information available only to law enforcement about who had access to various fluids. This highlights some of the problems in trying to prevent future occurrences.

The investigation by the SGH infection control team led to the tightening of procedures and the effective end of the outbreak soon after it was recognised.

The IRC report, however, highlighted structural issues which may have led to contamination of intravenous fluids by busy or distracted ward staff and which need to be addressed urgently.

In conclusion, this was a very unusual outbreak with a virulent virus and many lessons learnt for the Singapore clinical and public health communities.

I hope that the reaction will not be more bureaucracy but rather strengthening of existing surveillance systems and empowering healthcare workers at all levels to do what we are called to do - look after sick patients without doing them any harm, as the medical adage goes: Primum non nocere, first do no harm.

• The writer is an infectious diseases physician and lecturer who trained in the United States and Singapore. He was also a Singapore Democratic Party candidate in the last general election.

A version of this article appeared in the print edition of The Straits Times on December 12, 2015, with the headline 'Unusual factors in SGH hepatitis C outbreak'. Print Edition | Subscribe