Professor David Koh

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Occupational Health Conference Muscat, 11-13 Dec
2006
Emerging Infections and Health Care Workers
Professor David Koh MBBS, MSc, PhD, FFOM,
FFOMI, FFPH, FAMS Department of Community,
Occupational and Family Medicine Faculty of
Medicine
2
Emerging and Re-emerging Infectious Diseases,
1996 - 2001
SARS 2002-2003
Source WHO, 2003
3
SARS
Probable cases of SARS worldwide, 7 August 2003.
Source WHO
Cumulative Total 8,422 cases and 916 deaths,
reported from 29 countries
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SARS an occupational health threat

• 20 of SARS patients were HCWs (n1706)
• Range 19 in the China, 43 in Canada
• 57 in Vietnam
• Differential risk for different types of HCWs
• All HCWs (including traditional healers) are
  potentially at risk
• Even apparently low exposure situations can
  pose a risk

D Koh, Lim MK, Chia SE. SARS health care work
can be hazardous to health. Occupational
Medicine, 2003 53 (4) 241-3.
5
Attack Rate for Health Care Workers in the Hanoi
French Hospital Overall Attack Rate 18 Doctor
16 Nurse 35 Administrative staff 2 Other
staff with patient contact 53 Patients
admitted for other reasons - 7 Source WHO,
17 Oct 2003
6
Attack Rates among HCWs in Hong Kong 339 SARS
infected HCWs in 14 of 16 Hospital Authority
hospitals that managed SARS cases (0 - 3.6, 4.4
) Staff Category Attack Rate
Range Nurses 1.21 0 4.7
Medical / Technical 0.29 0
1.5 Non-medical support 2.73 0
13.3 Overall 1.2
Healthcare assistants, cleaners, clerical
staff
Lau JTF, Yang X, Leung P-C, Chan L, Wong E, Fong
C, et al. SARS in three categories of hospital
workers, Hong Kong. Emerg Infect Dis serial on
the Internet. 2004 Aug date cited. Available
from http//www.cdc.gov/ncidod/EID/vol10no8/04-00
41.htm
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High risk procedures - Intubation,
suction - Nebulized aerosol therapy -
Positive pressure non-invasive ventilation
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The Inanimate Environment Can Facilitate
Transmission
X represents VRE culture positive sites
Contaminated surfaces increase
cross-transmission Abstract The Risk of Hand
and Glove Contamination after Contact with a
VRE () Patient Environment. Hayden M, ICAAC,
2001, Chicago, IL.
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Proximity is Important Attack Rate of Medical
Students, Prince of Wales Hospital 100 - for
those who visited patients in beds adjacent
to an index case ( 3 / 3 ) 50 - for those who
entered the same cubicle as an index case (
4 / 8 ) 0 - for those who had only entered the
same ward ( 0 / 8 )
Wong T-W, Lee C-K, Tam W, Lau JT-F, Yu T-S, Lui
S-F, et al. Cluster of SARS among medical
students exposed to single patient, Hong Kong.
Emerg Infect Dis serial online 2004 Feb date
cited. Available from URL http//www.cdc.gov/nc
idod/EID/vol10no2/03-0452.htm
10

• The impact of SARS extends
  beyond the infection
• Psychological effects
• High degree of distress experienced by
  29 - 35 of hospital workers
• Overwork and job demands
• Social effects
• Effects on the family

Maunder R. The experience of the 2003 SARS
outbreak as a traumatic stress among frontline
healthcare workers in Toronto lessons learnt.
Phil Trans R Soc Lond 2004
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Study of SARS among HCWs in Singapore Objectives
To study - work and non-work related problems
among health care workers in Singapore
Study Design Questionnaire survey of 15,025
health care workers in 9 health care settings,
from May-July 2003
D Koh, C Fones, MK Lim, SE Chia, F Qian, V Ng, S
Emmanuel, NP Fong, G Koh, CT Kwa, BH Tan, KS
Wong, W Ng, Z Muttakin, KB Tan, WM Chew, HK
Tang, SM Ko. Impact of SARS on Health Care
Workers in Singapore. Medical Care 2005
Jul43(7)676-82.
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Impact on Family and Social life 82 were
concerned about passing SARS to family
members, close friends, or work
colleagues 87 agreed that people close
to me are worried for my health 69 felt that
people close to me are worried they might
get infected through me
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Impact on Family and Social
life Negative 49 thought that People
avoid me because of my job 31 felt that
people avoid my family members
because of my job Positive 82 of respondents
felt appreciated by the
hospital / clinic / my employer 77 felt
appreciated by society
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SARS a newly emergent occupational disease
Health care workers Animal and food
preparation handlers Transport workers
- flight attendants,
taxi drivers Laboratory Researchers
D Koh, Lim M-K, Ong C-N, Chia S-E. Occupational
health response to SARS. Emerg Infect Dis serial
on the Internet. 2005 Jan date cited.
Available from http//www.cdc.gov/ncidod/EID/vol11
no01/04-0637.htm
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Will SARS Re-emerge ?

• Most likely scenarios
• Original or new animal reservoir
• Undetected transmission in humans (?
  Seasonal)
• Persistent infection in humans
• Laboratory accidents

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Post July 2003 cases of SARS Lab Accident 1 -
Singapore Sep 2003 27 year old postdoctoral
student 23 Aug 30 minutes at lab working on
West Nile virus 26 August Developed fever at
midnight, later tested SARS ve Lab Accident 2
- Taiwan Dec 2003 44 year old military
researcher, at the Institute of Preventive
Medicine of the National Defense Medical Centre
1. Lim PL et al. Laboratory-acquired severe
acute respiratory syndrome.N Engl J Med. 2004
Apr 22350(17)1740-5. 2. Normile D.
Second Lab accident fuels fears
about SARS. Science 2004. Jan 2004, 303
26.
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Guangdong, China Dec 2003 Jan 2004

• 32 y/o male TV producer (rats in
  apartment)
• 20 y/o restaurant waitress
• , 4 35 y/o businessman, 40 y/o hospital
  medical director/physician Diners at
  restaurants (next door to, and at the restaurant
  where 2 worked)

FANG Ling et al. A serologic diagnosis and study
on SARS antibody of newly occurred 4 confirmed
SARS cases in 2003-2004 in Guangdong, PR China.
International Conference on SARS One Year After
the (first) Outbreak Musik- und Kongresshalle
Lübeck, Germany, May 8-11, 2004. Liang G, Chen
Q, Xu J, Liu Y, Lim W, Peiris JSM, et al.
Laboratory diagnosis of four recent, sporadic
cases of community-acquired SARS, Guangdong
Province, China. Emerg Infect Dis serial on the
Internet. 2004 Oct date cited. Available from
http//www.cdc.gov/ncidod/EID/vol10no10/04-0445.ht
m
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Beijing, April 2004
2 laboratory workers at the CDCs Institute of
Virus Diseases Health care worker Family
contacts 9 cases in all 1 death
Normile D. Severe acute respiratory syndrome
lab accidents prompt calls for new containment
program. Science. 2004 May 28304(5675)1223-5.
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Are We Prepared ?
Singaporean and Japanese Health Care Worker
Perceptions, 2003
Singapore Japan n 10,511 n
7,282 felt "At great risk of exposure
to SARS" 66 64 Afraid of
falling ill with SARS" 76 55 felt that
"Protective measures were effective" 96
31 thought that "Protective measures were
necessary and important" 95 88 felt that
Policies and protocols were
clear 93 65 thought that
Policies and protocols were
implemented" 90 50 felt that
Recommended measures were adhered to" 92
43
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Learning Point
Initial infections of HCWs at the outset of an
outbreak may sometimes be due to perceptions that
recommended policies and measures are unnecessary
or excessive.   . efforts to educate and
communicate the rationale and importance of
protective measures may be especially
important when outbreaks seem distant and
perceived danger is low.  
D Koh, K Takahashi, MK Lim, T Imai, SE Chia, F
Qian, V Ng, C Fones. SARS risk perception and
preventive measures, Singapore and Japan. Emerg
Infect Dis serial on the Internet. 2005 Apr
date cited. Available from http//www.cdc.gov/nc
idod/EID/vol11no04/04-0765.htm
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Influenza A Viruses
H1 H2 H3 H4 H5 H6 H7 H8 H9 H10 H11 H12 H13 H14 H15
N1 N2 N3 N4 N5 N6 N7 N8 N9
Orthomyxovirus - with 8 segmented ssRNA
genome Subtypes based on basis of two surface
antigens - Hemagglutinin (H) - Neuraminidase
(N) H1N1, H3N2 and H1N2 affect humans and are
globally circulated H5N1 - causes avian influenza
Source Nicholson, Wood and Zambon. Lancet
2003 362 1733-45.
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Why the Concern about H5N1 H5N1 strain mutates
frequently H5N1 has the capacity to jump the
species barrier to cause disease
in humans (documented in 1997,
2003, 04, 05) H5N1 infection in humans has a
high fatality rate Genetic mutation in the last
few years show increasing H5N1 virulence and
capacity to infect mammals ? Emergence of a new
subtype of virus that can infect humans and be
transmitted to other humans
Linda Stannard, of the Dept of Medical
Microbiology, University of Cape Town
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Hong Kong, SAR 1997

• 18 Human cases of H5 N1 influenza
• 9 were children lt 10 yrs
• 7 mild disease
• 11 severe with pneumonia
• 6 fatalities (lt 10 yrs, 1/9 gt 12 yrs 5/9)
• Close contacts with affected poultry
• Index case had contact with chickens and ducks
  in school
• 3 cases purchased poultry from market before
  illness
• 2 cases had live H5N1ve chicken outlet near
  their home
• 5 cases had regular visits to markets/live
  chicken outlets
• 1 case worked in the market

Tam JS. Influenza A (H5N1) in Hong Kong an
overview. Vaccine 20 (2002) S77-S81.
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29 Dec 1997 15 Jan 1998 Serological survey of
293 government workers (cullers) and 1525
poultry workers Poultry Workers 10 serove
for H5 (by microneutralization and Western
blot assay) Risk factors butchering poultry,
exposure to poultry with gt10
mortality Government Workers (Cullers) 3 were
serove for H5 229 (78) had paired serum samples
(2 wks later) 1 seroconverted (respiratory
illness on 27 Dec)
Bridges CB et al. Risk of Influenza A (H5N1)
infection among poultry workers, Hong Kong,
1997-1998. J Infect Dis 2002 185 1005-10.
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H5N1 Transmission to Health Care Workers
217 exposed, 309 non-exposed HCWs studied Exposed
and non-exposed HCWs reported no difference
in poultry exposure 89 of exposed HCWs had
paired serum samples 3.7 (8/217) of exposed
HCWs were H5N1 serove (2 of these exposed HCWs
seroconverted) 0.7 (2/309) of non-exposed HCWs
were H5N1 serove Risk factors
Bathing patient, changing bed linen of patient
From BBC
Bridges CB et al. Risk of influenza A (H5N1)
infection among health care workers exposed to
patients with influenza A (H5N1), Hong Kong. J
Infect Dis 2000 181344-8.
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As at 29 Nov 258 cases, 154 deaths
http//gamapserver.who.int/mapLibrary/Files/Maps/G
lobal_H5N1inHumanCUMULATIVE_FIMS_20061113(2).png
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H5N1 in Other Animals
Haiyan L. I. Chin J. Chinese J. Prev. Vet.
Med., 26. 1 - 6 (Jan 2004) H5N1 virus found in
2003 in pigs in southeast China Haiyan L. I.
Chin J. Chinese J. Prev. Vet. Med., 24. 304 -
309 (May 2004) Reported similar results from pigs
tested elsewhere in 2001 and 2003
H5N1 in CATS leopards, tigers, domestic cats
http//www.fao.org/ag/againfo/subjects/en/health/d
iseases-cards/avian_cats.html
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• Report of probable person to person transmission
  of bird flu in Thailand
• Index patient (Sep 2004)
• 11 year old girl, who became ill a few
• days after exposure to dying chickens
• Mother (no history or poultry exposure)
• travelled from distant city to provide
• 16-18 hours of unprotected nursing care
• Mother died from pneumonia autopsy tissue ve
  for H5N1
• Aunt also provided unprotected nursing, and
  developed fever and pneumonia
• Nasopharyngeal throat swabs ve for H5N1
• K. Ungchusak et al. Probable person-to-person
• transmission of avian influenza A (H5N1).
• New Engl. J. Med, 2005 352 333340. 27 Jan 2005

Patient Mother Aunt

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SCIENCE Vol 308 No 5721 22 April 2005
Update on North Vietnam - 70 mortality
previously - 20 mortality since Jan 2005 -
Cases occur in larger clusters e.g. 5 members
in one family - Previously among children, young
adults, but now affects people of all ages -
Disease appears to be less virulent and more
infectious - Still ? no evidence of person-person
transmission
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Influenza Pandemics in the Last Century
1918-19 Spanish Influenza H1 N1 30 million
deaths 39 years later . . . 1957-58 Asian
Influenza H2 N2 1 million deaths 11 years
later . . . 1968-69 Hong Kong Influenza H3
N2 800,000 deaths 38 years later . . .
winter 2006 ? ? ?
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Summary Several viral zoonotic
diseases have recently emerged Occupational
exposures are relevant in many cases
Healthcare workers are at risk Illnesses are
severe with mortality rates of
10-75 These outbreaks recur - we should be
alert prepared