Replies to LegCo questions
LCQ5: Tuberculosis cases
Following is a question by the Dr Hon Joseph Lee and a written reply by the
Secretary for Health, Welfare and Food, Dr York Chow, in the Legislative Council
today (March 16):
Question :
It has been reported that a survey undertaken by the Department of Health
reveals that the incidence rate of pulmonary tuberculosis for children aged
below nine in Hong Kong is ten times that of Europe and the United States of
America and two times that of Japan. Information from the Labour Department
shows that while the total number of occupational disease cases in 2004
decreased by 31 per cent compared to that in 2002, tuberculosis cases increased
by 44.8 per cent. In this connection, will the Government inform this Council:
(a) of the respective numbers of local children, adults and the elderly who
contracted pulmonary tuberculosis in the past three years and their major
sources of infection;
(b) of the respective numbers of patients and hospital staff who were confirmed
to have contracted pulmonary tuberculosis during hospitalization and while on
duty in the past three years, together with a breakdown by the ranks of the
staff and whether they worked in public or private hospitals; and
(c) whether it has analyzed the reasons for the high incidence rate for children
and an upsurge in cases of staff contracting tuberculosis while on duty, and
formulated measures to prevent the situation from deteriorating; if it has, of
the results of the analysis and details of the measures?
Answer:
Madam President,
Tuberculosis (TB) is an infectious disease affecting mainly the lung caused by
the bacteria Myobacterium tuberculosis. TB spreads mainly through the air by
droplets. Among those infected, about one out of 10 will develop the disease as
a lifetime risk, after a variable latent period of weeks to decades. The other
nine infected will remain healthy without developing disease, because the immune
system 'walls off' the bacteria and the infection remains latent. Thus, a
patient developing TB disease might have got the infection a long time ago, and
the source of infection for the great majority of the cases is therefore
unidentifiable.
Given the very variable and long latent period of the disease, trend analysis of
the disease pattern is considered more meaningful if it is conducted over a long
period of time. The notification rate(Note 1) of TB in Hong Kong in the past
five decades is decreasing, from the peak of 697 in 1952 to 91.5 in 2004(Note
2).
Development of TB situations in different places can also vary significantly due
to their unique evolvement in socioeconomic conditions like population density,
general hygiene awareness, nutritional level, living environment, economic
well-being, etc. Moreover, the epidemiological development of TB in different
places probably started during different historical times which are decades or
centuries from now, thus their manifestations at similar time point can be
rather different. This should also be taken into account when comparing the
epidemiological condition of TB of one place to another. In fact, the rate of TB
in Hong Kong has been higher than those of some western developed countries for
many years, and some experts have attributed a possible reason for this to the
different moments in history of the onsets of the TB epidemic in Hong Kong and
those developed countries.
(a) The numbers of notification compiled by the Department of Health (DH) are
categorised into different age groups. The statistics in the past three years
are shown in
Table 1. It should be noted that, as described in the introduction
paragraphs, the total TB cases in Hong Kong display a decreasing trend over half
of the past century.
As TB is an airborne disease which can be spread from person to person via
airborne droplets from coughing and sneezing of people with active TB, and that
the disease exhibits a latent period which can vary significantly among
individuals, the source of infection for most of TB cases is unidentifiable.
(b) For the reasons mentioned in part (a), we do not have the number of patients
who were confirmed to have contracted TB during hospitalization.
Under the Occupational Safety and Health Ordinance (Cap. 509), TB is a
notifiable occupational disease. It is a statutory requirement for medical
practitioners to notify all occupational TB to the Labour Department (LD). The
statistics for the past three years, with breakdown of the healthcare workers by
their positions and the public/private nature of their employing institutions,
are shown in
Table 2.
(c) The prevalence of TB in Hong Kong has been higher than those of some
developed countries in the past few decades. It could be attributed to a number
of factors including the unique development history of the disease in different
places, and their varying socioeconomic developments. As far as the 0-9 age
group is concerned, it should be noted that the notification rates found in this
age group show a decreasing trend in the past two decades, with the notification
rate dropping from 13.01 in 1984, to 7.37 and 2.33 in 1994 and 2004
respectively.
On the basis of the reasons set out in the introduction paragraphs and paragraph
(a) above, the Administration considers that the increase of the number of
healthcare workers believed to have contracted TB in the healthcare setting in
the past three years could probably be due to year-on-year fluctuation.
Nonetheless, the Administration will keep a close watch on the trend, and refine
disease prevention and control strategy as appropriate.
The Department of Health (DH) has been putting in a lot of efforts in the
prevention and control of TB in Hong Kong. Nearly 100 per cent of newborn babies
are provided with BCG vaccination which is efficacious for the protection
against TB. Other measures, including application of directly observed
treatment, infection control, and stringent surveillance mechanisms, will
continue to be implemented. Also, DH will continue to maintain close liaison
with international counterparts and engage in research activities for
improvement in the control of the disease.
Infection control is essential for the prevention of transmission of TB in
healthcare settings, and on this front, DH is in close collaboration with the
Hospital Authority (HA) and private hospitals. Activities will continue to be
organised to educate health care workers working in hospitals, clinics,
residential care homes for the elderly etc. on issues like early recognition and
treatment of the disease, maintenance of adequate ventilation, use of personal
protective equipment like face masks, as well as precautions to be taken during
high risk procedures like cough-inducing procedures.
Further to the above, HA has promulgated a set of guidelines on "Control of
Transmission of TB in Healthcare Settings" to inform frontline staff of the
necessary infection control measures to prevent patients and healthcare workers
from contracting the disease in the healthcare setting. The guidelines have been
posted on the HA intranet webpage for easy reference of staff.
Meanwhile, LD has stepped up inspections to hospitals, clinics and elderly
homes, which are considered as high-risk workplaces, to ensure that the
ventilation of these workplaces meets the standard, and the staff are provided
with adequate personal protective equipment and given training on its use.
Notes:
(1) The notification rate is the number of notifications per 100,000 population
(2) This is a provisional figure, which is being verified by DH for the purpose
of formal publication.
Ends/Wednesday, March 16, 2005
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