????????? The Current Situation of Infectious Diseases in Hong Kong

1
?????????The Current Situation of Infectious
Diseases in Hong Kong

• ??????? ???????
• ??????
• ?????
• Dr. Sik-To Lai, Consultant Physician and Head of
  Infectious Disease
• Department of Medicine and Geriatrics
• Princess Margaret Hospital
• Hong Kong SAR

2

• Today, infectious diseases are not only a health
  issue they have become a social problem with
  tremendous consequences for the well-being of the
  individual and the world we live in.
• Hiroshi Nakajima, MD, PhD
• Former Director-General
• World Health Organisation, 1996

3
Introduction

• The end of infectious diseases was a popular
  idea in the 1970s
• Infectious diseases are still important in the
  21st century due to
• Boundless nature
• Emergence of new infections
• Re-emergence of old infections
• Increase in drug - resistant infections

4
Incidence

• 27 statutory notifiable infectious diseases in
  Hong Kong which are reported to the Department of
  Health (DH) of the Hong Kong SAR Government
• The top five diseases in 2001 were chickenpox,
  tuberculosis, viral hepatitis, food poisoning and
  bacillary dysentery
• No exact figure for non-notifiable infectious
  diseases in the community and hospitals. Many of
  these diseases are very important and numerous in
  number, e.g. influenza, otitis media, pneumonia,
  urinary tract infection etc.

5
Comparison of the Number of ID Notifications in
2000 with the Mean of 1995-1999
6
No. of Notifications for Notifiable Infectious
Diseases in 2001

• Cholera 38 Meningococcal infections 10
• Plague 0 Mumps 76
• Yellow fever 0 Paratyphoid fever 21
• Acute poliomyelitis 0 Rabies (Human) 1
• Amoebic dysentery 7 Relapsing fever 0
• Bacillary dysentery 389 Rubella 57
• Chickenpox 16,501 Scarlet fever 147
• Dengue fever 17 Tetanus 4
• Diphtheria 0 Tuberculosis 7,262
• Food poisoning (outbreaks) 672 Typhoid fever 67
• Food poisoning (affected) 2,709 Typhus fever 7
• Legionnaires Disease 3 Viral hepatitis A 482
• Leprosy 10 Viral hepatitis B 125
• Malaria 47 Non-A, non-B hepatitis 39
• Measles 182 Unclassified hepatitis 33
• Total 26,212

7
Deaths from Notifiable Infectious Diseases

• There were 310 deaths from notifiable infectious
  diseases in 2000
• 299 were due to tuberculosis (96)
• The rest were due to
• Viral hepatitis 4
• Tetanus 2
• Chickenpox 1
• Malaria 1
• Meningococcal infections 1
• Rabies 1
• Typhoid fever 1

8
Surveillance and Management

• Infectious disease surveillance is undertaken by
  the Disease Prevention and Control Division of
  the Department of Health
• A number of DH and private clinics act as
  sentinel surveillance points
• Notifiable infectious diseases are admitted into
  the Infectious Disease Unit of Princess Margaret
  Hospital. Three diseases are quarantinable,
  including cholera, plague and yellow fever
• Non-notifiable infectious diseases are managed in
  clinics and hospitals at large

9
Important Infectious Diseases in Hong Kong

• By the number and seriousness, there are 3
  important infectious diseases in Hong Kong
  tuberculosis, HIV/AIDS and sexually transmitted
  infections
• These diseases are managed by special clinics and
  staff due to public health , expertise and
  resources considerations

10
Viral Hepatitis in Hong Kong 1988 - 2000
11
Hepatitis (1)

• The incidence was 679 cases in 2001
• Hepatitis A 482
• Hepatitis B 125
• Non-A, non-B hepatitis 39
• Unclassified hepatitis 33
• Hepatitis A
• No major outbreak after 1992, apart from some
  minor outbreaks especially in mental institutions
• Prevalence of hepatitis A antibody found to be
  10 and 30 in people aged lt 11 and lt 30,
  respectively. Large pool of non-immune
  individuals
• No formal hepatitis A vaccination programme from
  the government

12
Hepatitis (2)

• Hepatitis B
• Hepatitis B vaccine is given to all newborns in
  Hong Kong
• Overall carrier rate around 10 with much lower
  prevalence in children
• Acute hepatitis B has become a largely
  sexually-transmitted disease
• Interferon and antivirals are used in the
  treatment of chronic hepatitis B
• Hepatitis C
• Found in 0.5 of blood donors
• HCV Look Back Programme of the Hospital Authority
• Interferon and ribavirin are used in the
  treatment of chronic hepatitis C
• Hepatitis E
• 40 of non-ABC hepatitis
• Similar picture to hepatitis A
• 11 of hepatitis A have hepatitis E co-infection

13
Cholera

• Mainly imported cases from neighbouring endemic
  areas
• Contaminated shell-fish has been the culprit in
  many cases
• Polluted seawater in fish tanks was implicated in
  some restaurant outbreaks
• Minimal mortality but reports of acute renal
  failure in the elderly and ill
• Fluoroquinolones are now drugs of choice
• Vaccination is not recommended

14
Enteric Fever

• Many cases are imported (13.4) and most common
  in young adults
• Cause of pyrexia of unknown origin
• Previous antibiotic therapy renders blood culture
  negative
• Maybe mistaken as surgical emergencies
• Most common complication is gastrointestinal
  bleeding
• Widal test is not clinically useful
• Multi-drug resistant (MDR) strains are common
• Fluoroquinolones are the drugs of choice
• Chronic carrier rate of 2 5
• Oral and parenteral vaccines are available

15
Dysentery

• The most common organism in bacillary dysentery
  is Shigella sonnei
• Outbreaks have been reported in mental
  institutions
• Similar clinical features are found in infection
  caused by Vibrio parahaemolyticus and Plesiomonas
  shigelloides
• Fluoroquinolones are the drugs of choice

16
Food Poisoning

• Compared with 1999, there was a 15 increase in
  the number of outbreaks and a 13 increase in the
  number of persons affected in 2000
• Majority of outbreaks were small (96) affecting
  less than 10 persons
• About half occurred in food premises and most of
  the rest occurred at home
• Top five causative agents in terms of the number
  of outbreaks were
• Vibrio parahaemolyticus (36)
• Staphylococcus aureus (18)
• Salmonella spp. (14)
• Clenbuterol (6)
• Ciguatoxin (5)

17
Viral Gastroenteritis

• Commonly due to Norwalk-like viruses
• Increase in number of outbreaks in Hong Kong
• Residential homes and schools
• Isolated cases among people of all age groups
• Food may be contaminated at the source, e.g.
  oysters harvested from sewage contaminated water,
  or by food handlers
• Aerosol spread also occurs from the vomitus
• Prevention is by strict observance of food,
  environmental and personal hygiene

18
(No Transcript)
19
Malaria (1)

• Around 80 are due to Plasmodium vivax and 17
  are due to Plasmodium falciparum
• The main areas of acquisition are China, Indian
  Subcontinent, Southeast Asia and Africa
• Indigenous cases also occur
• Low mortality of 5 out of 862 from 1991 2000.
  All the deaths were due to cerebral malaria and
  multi-organ failure in Plasmodium falciparum
  infection

20
Malaria (2)

• Chloroquine is used for Plasmodium vivax, ovale
  and malariae
• Quinine plus tetracycline or mefloquine alone are
  used for Plasmodium falciparum infection
• Quinine-resistant cases of falciparum malaria
  were found and the patients had exposure in the
  Thai-Cambodia border
• Artemisinin plus tetracycline / mefloquine have
  been used with success
• Mefloquine is the preferred drug for
  chemoprophylaxis
• Travel clinics run by the DH and PMH can offer
  advice, drugs and vaccines

21
Dengue Fever

• Occasional cases in Hong Kong, all with a history
  of travel to endemic areas
• The vector mosquito Aedes albopictus is found in
  Hong Kong
• Outbreak of around 1500 cases in Macau last
  summer to autumn
• No evidence of spread to Hong Kong
• Diagnosis is by rise in antibody titre
• No report of dengue haemorrhagic fever
• Conservative treatment blood transfusion

22
Chickenpox / Herpes Zoster (1)

• Became a notifiable infectious disease since Feb,
  1999
• Top in incidence in 2001 16,501 cases
• Most cases were children aged 10 or below
• Southeast Asian domestic helpers (e.g. from the
  Philippines etc.) were most common among adult
  patients
• Complications have been uncommon (lt 1) and in
  2000 included
• Scarlet fever (24)
• Pneumonia (9)
• Sepsis (4)
• Other group A streptococcal infections (4)
• There was one death involving an
  immunocompromised person in 2000

23
Chickenpox / Herpes Zoster (2)

• Strict isolation in hospital
• Early antiviral treatment shortens duration of
  symptoms and pain
• Given within 24 hours of rash in chickenpox
• Given within 72 hours of rash in herpes zoster
• Antiviral therapy used for all cases of severe
  chickenpox or herpes zoster in the elderly or
  immunocompromised patients
• Varicella-zoster immunoglobulin given within 96
  hours of exposure can prevent / modify disease in
  contacts
• Chickenpox vaccine is available and can achieve gt
  90 seroconversion

24
Measles

• Immunisation programme for measles has been in
  place since 1967
• MMR (Measles, Mumps, Rubella) vaccine is given to
  children at 12 months of age and at primary one
  in Hong Kong
• Adult cases of measles are still present due to
  failure to take the booster dose of vaccine and
  waning antibody titre
• May cause severe disease in adults, especially
  pregnant women and immunocompromised patients
• Respiratory isolation required
• Immunoglobulin may be used within six days of
  exposure for susceptible contacts

25
Rubella

• Disease is preventable by MMR vaccine
• Problem of waning antibody titre as in measles
• Booster dose at primary six is important
  especially for girls prevention of congenital
  rubella of fetus in pregnancy (2 cases in 2000)
• High notification rate of rubella in recent years
  especially in young adults
• There were 4 cases of rubella encephalitis in the
  outbreak between 1996 1997 and 1 died

26
Mumps

• Cases are continuously reported but there have
  been no epidemic outbreaks
• Besides parotitis, the virus can cause orchitis,
  oophoritis, lymphocytic meningitis, pancreatitis,
  post-infectious encephalitis, thyroiditis and
  arthritis
• Symptomatic treatment
• NSAIDs but not corticosteroids for pain of
  orchitis

27
(No Transcript)
28
Influenza (1)

• Not notifiable in Hong Kong
• Trend is monitored by sentinel surveillance in DH
  and private clinics with regard to the number of
  influenza-like illness and sample isolates from
  nasopharyngeal aspirates and throat swabs
• Peak season is spring in Hong Kong
• The main circulating serotypes are
• H3N2 A / Sydney / 5 / 97, Moscow / 10 / 99,
  Panama / 2007 / 99 - like virus
• H1N1 A / New Caledonia / 20 / 99 like virus
  
• B / Hong Kong / 330 / 01 like virus has become
  the predominant B serotype since October 2001 and
  has replaced the B / Sichuan / 379 / 99 - like
  virus prevalent in the last few years
• WHO recommends that the new vaccine for the
  Northern Hemisphere this year should consist of
  the Moscow, New Caledonia and Hong Kong strains

29
Influenza (2)

• Can given rise to complications like secondary
  bacterial pneumonia, myocarditis, encephalitis,
  Guillain-Barré syndrome, etc.
• Increases morbidity and mortality in the elderly
  and immunocompromised patients
• Amantadine and rimantadine have been in use and
  are active against influenza A
• Neuraminidase inhibitors like zanamivir and
  oseltamivir are active against influenza A and B
• Influenza vaccines are available for influenza A
  and B and are usually given in November to
  December
• Annual vaccination programme for residents of
  aged homes and patients of long - stay facilities

30
Meningococcal Infections

• Notifications rose sharply from 3 cases in 1999
  to 14 cases in 2000 and 10 cases in 2001
• All were sporadic cases affecting patients of
  different age groups
• 3 cases were imported from Mainland China
• Half of the cases presented with signs and
  symptoms of meningitis and the other half those
  of septicaemia
• The predominant serogroup was B (5) and the other
  serogroups were W135 (3), A (1) and non-B (1)
• No cases of death notified in recent 2 years

31
Rabies

• Hong Kong had been free from rabies since 1988
  until one case appeared in 1999
• After that case, another one appeared in 2001
• Both were Filipino domestic helpers who had a
  history of travel back to the Philippines
• The first had a history of dog bite and the
  second did not
• Diagnosed as viral encephalitis initially
• Correct diagnosis was reached in the first one
  antemortem and in the second one postmortem

32
Legionnaires Disease

• Presents as severe community-acquired pneumonia,
  mild cases will be missed
• No reported case was proved by culture
• Diagnosis was established by retrospective
  finding of rise in antibody titres in suspected
  cases
• No nosocomial case in Hong Kong despite
  ubiquitous presence of the organism
• Recent report of 3 cases in Hong Kong, 2 in
  October and 1 in December 2001
• All 3 patients were residents of the Kwun Tong
  area
• ? Related to polluted water cooling tower

33
Leptospirosis

• Notifiable occupational disease in Hong Kong
• One case notified in June 2001
• The local geographical, economic and behavioural
  factors do not favour a high risk of exposure
• Rodent infestation, flooding, skin abrasions and
  use of bare hands to touch possibly contaminated
  articles and probing drains are potential risk
  factors

34
Antibiotic Resistance

• Growing global trend of microbial resistance to
  many antibiotics due to indiscriminate and
  extensive use
• A sentinel surveillance system for antibiotic
  resistance was initiated by DH in 1999,
  comprising private clinics and GOPCs
• DH published the Guideline on Antimicrobial Use
  in Primary Health Care Clinics in January 2002
• Physicians and microbiologists of the HA formed
  the Interhospital Multi-disciplinary Programme on
  Antimicrobial ChemoTherapy (IMPACT) in 1999 and
  published the second draft edition of the
  handbook Reducing bacterial resistance with
  IMPACT in July 2001

35
Methicillin-Resistant Staphylococcus aureus

• Prevalence of nearly 60 of isolates in some
  hospitals in Hong Kong
• Typically found in debilitated patients on
  antibiotics
• Community-acquired infections are increasingly
  reported
• Prevalence related to the use of antibiotics and
  degree of contact precautions, especially hand
  washing

36
Penicillin-Resistant Streptococcus pneumoniae

• Prevalence of intermediate penicillin resistance
  in Streptococcus pneumoniae is more than 60 in
  Hong Kong
• Resistance to other antibiotics like
  erythromycin, tetracyclines, co-trimoxazole and
  clindamycin
• More liberal use of pneumococcal vaccine in
  broader categories of patients now seems justified

37
Bioterrorism

• Worldwide threat of terrorism caused by agents of
  biological disasters after the 911 incident in
  USA
• Joint Working Group between the Security Bureau,
  Department of Health and Hospital Authority
  formed in November 2001
• Guidelines for the management of suspected and
  confirmed cases of exposure to anthrax were
  formulated and promulgated
• The Hospital Authority Task Force on Infection
  Control had also prepared fact sheets on
  smallpox, plague, botulism and viral haemorrhagic
  fevers for reference and use by HA hospitals

38
Recent Trend in Infectious Diseases in Hong Kong

• Notifiable infectious diseases are limited in
  number
• Infectious disease physicians are now
  concentrating their efforts on
• HIV/AIDS
• Infections of immunocompromised patients
• Neutropenic infections
• Critical care infections
• Nosocomial infections
• Infection control
• Antibiotic policy etc.

39
Conclusions

• The prevention and treatment of notifiable
  infectious diseases in Hong Kong have reached
  international standard
• The trend now for modern infectious disease
  physicians is to concentrate more on other
  activities like HIV/AIDS, infections in
  immunocompromised patients, nosocomial infections
  and antimicrobial resistance etc.
• Public health education and disease awareness of
  Hong Kong citizens still needs to be intensified