Leptospirosis: our most common infectious disease acquired in the workplace

1
Leptospirosis our most common infectious disease
acquired in the workplace

• Dr. Jackie Benschop
• Assoc. Prof. Cord Heuer
• Rural Women New Zealand
• National Conference
• Rotorua 15 May 2007

2
Outline

• Introduction
• What is Leptospirosis?
• The NZ situation
• Crucial early role of Womens division federated
  farmers
• NZ leptospirosis pattern is changing
• EpiCentre Recent and on-going Leptospirosis
  studies
• What we need to do next

3
What is Leptospirosis?

• Primarily a disease of wild and domestic animals
• Can cause animal disease but often silent
  shedders
• Humans easily infected by contact with infected
  animal urine
• Enters through cuts and cracks in the skin, e.g.
  through bare hands or feet, or through the
  membranes of the eyes, nose and mouth
• Causes vasculitis lots of different symptoms
  from mild flu to death

4
(No Transcript)
5
Leptospirosis NZ situation

• Huge improvements since the 1970s BUT
• It remains our most important occupational
  infectious disease
• It is poorly controlled in comparison with other
  developed countries

6
88 cases notified in 2006
Source ESR 2007
7
Under-ascertainment of cases

• For every notified case how many in the
  community?
• Many individuals will not seek medical help
• Self-employed
• Access to health care
• Flu-like symptoms
• Recognition by doctors has been poor (but
  improving)
• Differential bias
• Laboratory surveillance notification (also
  improving)
• No test at acute stage
• Estimated 4 to 6 fold under-reporting (source
  OSH 2001)

8
NZ history and role of RWNZ

• 1973-1974 campaign Womens Division Federated
  Farmers (now RWNZ) ? vaccination of dairy cattle
  and pigs and risk reduction strategies
• Recognised in international scientific
  literature
• In some countries rural women were the prime
  initiators of zoonotic disease programmes such as
  the successful echinococcus eradication and
  leptospirosis control initiatives in New Zealand
  

Source Background paper WHO 1999 Functions of
Veterinary Public Health
9
Role of RWNZ

• Recognised in national scientific literature
• Members of the Women's Division Federated
  Farmers saw the toll that was caused by
  leptospirosis in rural workers and raised a
  considerable amount of money to fund research
  into the problem at Massey University
• Recognised by NZVA
• Val Tarrant (then WDFF president) received first
  NZVA presidents award for this

Source Marshall and Manktelow, NZVJ, 2002 50
years of Leptospirosis research in NZ a
perspective
10
Promotion campaign and vaccine against pomona and
hardjo introduced 1979
1974 875 cases
1979 677 cases
1981 325 cases
1982 179 cases
11
Outline

• Introduction
• What is Leptospirosis?
• The NZ situation
• Crucial early role of Womens division federated
  farmers
• NZ leptospirosis pattern is changing
• EpiCentre Recent and on-going Leptospirosis
  studies
• What we need to do next

12
NZs lepto. epidemiology is changing

• Disease control in dairy cattle and pigs has
  improved
• However 10 dairy farms not vaccinating
• All stock need regular, well-timed vaccination
• Leptospirosis now emerging in sheep and deer
  (lamb and weaner losses)
• And emerging as a new source for human infections
• Meat-workers in sheep only abattoirs
• In Southland human cases associated with deer
  slaughter plants
• Less in dairy farmers (2003 cf 1990) and more in
  other farmers and meat-workers

13
Who is getting it? This hasnt changed.
Source Baker and Lopez The changing
epidemiology of human leptospirosis in NZ
(2004).
14
Occupational exposure (2001-2003, n 355)
Who is getting it? This has changed
Dairy farmers 10
Unknown 9
Other animal exposure 16
Other farmers 27
Meat workers 38
15
Where are they getting it? This has changed
Source Baker and Lopez The changing
epidemiology of human leptospirosis in NZ
(2004).
16
Outline

• Introduction
• What is Leptospirosis?
• The NZ situation
• Crucial early role of Womens division federated
  farmers
• NZ leptospirosis pattern is changing
• EpiCentre Recent and on-going Leptospirosis
  studies
• What we need to do next

17
Massey University EpiCentre

• We develop collaborative, interdisciplinary
  research programmes
• Zoonotic disease, veterinary public health, food
  chain
• Infectious and production-limiting disease
• These directly affect rural health and well-being
• Leptospirosis in sheep, deer, wildlife and people
• Risk attribution Campylobacter
• HPAI contacts between poultry industry and
  backyard producers, wild-bird surveillance
• Rural asthma childhood studies with public health
  group
• Surveillance for zoonotic disease in disrupted
  countries
• Bovine Tuberculosis and Johnes disease

18
EpiCentre 2006 Leptospirosis work

• Level of shedding on farm and at abattoirs (both
  deersheep)
• Vaccine efficacy and epidemiology in deer
• Prevalence in beef cattle
• There is a lot of leptospirosis in these animals

19
Kidney culture
Source Dorjee and Heuer 2006
20
New infections on one large farm (45,000 sheep)
with an outbreak and 20 lamb loss in the
previous year
Slaughter-house surveillance done here
21
EpiCentre Studies we need to do

• Sero-conversion rate among farmers and abattoir
  workers
• What are the risk factors?
• If there is economic loss, than control may be
  acceptable
• Estimate economic loss on sheep farms
• Transmission between species sheep, cattle,
  deer, wildlife
• Vaccine efficiency
• Longitudinal studies in beef, sheep and deer
  farms
• When are farmers most at risk?
• Develop science-based risk management strategies
  for beef, sheep and deer farms

22
Leptospirosis take home messages

• It mainly affects rural people and it can be a
  very nasty disease
• NZ has high rates compared to other developed
  countries
• RWNZ has been involved in the dramatic reduction
  of human cases in the 1970s and 1980s
• It is still the most important directly
  transmitted zoonosis in NZ
• We need to know more about lepto in sheep, beef
  cattle and deer to work out how best to control
  it and reduce the risk to humans