Experts fear return of Hong Kong’s No 1 killer, TB, amid rise in visitors from disease hot spots and drug resistance
Deaths from tuberculosis peaked in Hong Kong in 1951, but with an increase in antibiotic-resistant strains, more tourists from disease hot spots, and the city’s growing number of elderly, doctors fear a resurgence
Dr Chan Shiu-lun is well qualified to identify the signs of tuberculosis from the chest X-ray of a young Hong Kong man, diagnosed with the deadly disease. The chest physician and honorary consultant to the Hong Kong Tuberculosis, Chest and Heart Disease Association, points to a distinctive white circular shadow, which he says is a cavity in the upper right section of the patient’s lung.
In Hong Kong, tuberculosis (TB) – also known as “consumption” or the “white plague” – was once the city’s biggest killer. In the decade after the second world war, when poor immigrant communities were often crowded into cramped, insanitary makeshift shacks, TB was rampant. Annual deaths from the disease were three times the number killed by the outbreak of severe acute respiratory syndrome (Sars) in 2002 and 2003. In 1951, fatalities peaked at 4,190 (or 208 for every 100,000 of the population), but these days it’s often dismissed as a nasty disease from the distant colonial era.
“TB is still with us and it’s still killing people,” says Chan.
Although concerted government effort has drastically reduced TB incidence since its peak, it still affects thousands in the city, he says. The latest figures show there were 4,412 new cases in Hong Kong last year, resulting in 155 deaths. TB is rarely reported in mainstream media but there are growing fears of an international comeback.
A comprehensive report published in 2016 by the World Health Organisation (WHO) revealed TB to be one of the top 10 causes of death worldwide, claiming more lives than HIV or malaria. In 2015, 10.4 million people fell ill with TB and it claimed 1.8 million lives. According to the WHO, six high-TB- burden countries accounted for 60 per cent of the total, with India leading the count, followed by Indonesia and China.
China has a huge challenge trying to control TB and is making vigorous efforts. Besides an official WHO estimate of one million new cases in China in 2015, there are a growing number of new cases of multidrug resistant TB. Multidrug resistant TB is a particularly dangerous form of drug-resistant TB. It’s defined as when TB bacilli are resistant to at least isoniazid and rifampicin, the two most powerful anti-TB drugs. In China, it is estimated there were 63,000 new multidrug resistant TB cases in 2015 and the country is the source of about one third of all the world’s multidrug resistant TB cases.
Medical staff are also concerned about the recent emergence of the rarer extensively drug resistant, which is also resistant to any fluoroquinolone and at least one of the three injectable second-line drugs.
With about 45 million visitors to Hong Kong from China in 2015, and a political agenda of greater integration, health experts are concerned.
“China has the second biggest TB burden in the world and they send 100 million tourists all over the world every year – don’t you think that is high risk?” says Steve Lan Yee-fong, chairman of the Hong Kong Tuberculosis, Chest and Heart Disease Association. He says there is no move to introduce health screening for visitors from China or other high-TB-burden nations, though it is standard practice in many other nations, including the US and New Zealand.
“With the heavy traffic between Hong Kong and China, this is like a ticking time bomb,” he says.
Lan is not alone in his concern. A special report published in the Hong Kong Medical Journal in 2015 looked specifically at the impact of immigrant populations on the epidemiology of tuberculosis in Hong Kong. It concluded that “immigrants carry with them a higher tuberculosis incidence and/or drug resistance rate from their place of origin”. It also stated that the higher drug resistance rate, poorer treatment outcome, and excess relapse risk “raised concerns over secondary transmission of drug resistant TB within the local community” and there were “critical areas of concern”.
When asked about the 2015 report, the Department of Health did not mention the need for screening procedures and played down the risk of local TB infection from immigrants from high burden areas such as China.
“The gaps in TB prevalence are relatively narrow between Hong Kong and different parts of [China}. While higher TB prevalence is reported in some Asian countries, the risk differentials between them and Hong Kong might be less pronounced as compared to the corresponding ones between them and some low-TB-prevalence areas in Western Europe or the United States” a department spokesman says.
The development of and risk from multidrug resistant and extensively drug resistant TB is also home- grown, and not just an import from infected visitors.
“Directly observed treatment is essential to avoid the development of drug resistant TB,” says Chan, referring to the practise common in Hong Kong for drugs to be administered by medical staff to ensure patients complete the six-month treatment. This can be challenging in highly mobile and transient population like Hong Kong’s, and this is something the department is also concerned about.
“Mobile populations often have treatment-adherence problems. Irregular or incomplete treatment not only increases the risk of treatment failure or relapse, but may also lead to the emergence of drug resistance, which is an emerging global problem,” the spokesperson says.
Lan points out that the problem may soon become acute because antibiotics are currently the only proven treatment for TB. His association is calling for more research into new TB treatments that would be more effective in combating the drug resistant strains.
“We are not short of funding for treatment of TB cases. We are short of research into new and more effective treatments,” he says.
“There is no new treatment, and bacteria are always evolving and developing resistance to antibiotics so that some are now totally drug resistant and that is very dangerous in a heavily populated area like Hong Kong,” he adds.
Population density is a major factor in the spread of TB; it is estimated that one untreated patient can infect 12 other people in a year as the tubercle bacillus is transmitted through the air via small particles of sputum emitted from the infectious person via coughing, spitting or just talking.
Images of overcrowded MTR trains, full of coughing passengers, come to mind as Chan also reveals that about 30 per cent of people in Hong Kong are latent TB carriers. These are people exposed to the disease earlier in life who may only start to exhibit symptoms when the immune system is weakened due to illness or old age.
Chan says that two to three years ago, the Department of Health started a treatment campaign for residents with latent TB, focusing on those under the age of 35 in close contact with a diagnosed TB patient, and those with HIV and other forms of compromised immune system.
There were practical difficulties, however: a healthy young person with no apparent symptoms of TB, or any other disease, will be reluctant to take a six-month course of drugs just so they can be potentially healthier in later life. This is why countries including the US have introduced compulsory preventive intervention treatment.
Chan also thinks Hong Kong’s ageing population is as much of a threat to TB rates as TB-infected Chinese visitors coughing on the MTR. He points to statistics that show only 65 of the 4,412 reported cases in 2016 were attributed to Chinese immigrants staying in Hong Kong for less than seven years.
“The most important problem is the ageing population – the elderly have been infected much earlier in life, and when you look at the TB incidence rate, it is much higher in the over 65s,” says Chan. According to the Census and Statistics Department, the proportion of people aged 65 and over is projected to rise markedly, from 15 per cent of the population in 2014, to 36 per cent in 2064.
TB remains the only disease in Hong Kong treated free of charge by law. Given its deadly history and the pending threat of a re-emergence, no one in the medical world is feeling complacent.
“The Centre for Health Protection of the Department of Health has been putting major emphasis on coordinating TB control efforts in Hong Kong,” the spokesman says.
In 1949, the Hong Kong Anti-Tuberculosis Association built the Ruttonjee Sanatorium on the site of the previous Navy Hospital, to provide specialist services for TB patients. It took concerted efforts by the association and government to eventually produce a year-on-year decline in the number of TB cases. In 1967, this newspaper published a report headlined: “TB – Hong Kong’s No 1 Killer – is gradually being overcome.”
No one wants to see the statistics for TB deaths climb again, but it looks increasingly likely.
“It’s very difficult to predict, but if we don’t take the right measures those numbers could rise again,” says Chan.