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Table A2: Estimates of the annual background burden of water-borne disease in New Zealand

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Waterborne illness in New Zealand

Pathogen

Total incidence per 100,000 (corrected for under-reporting)

Reported incidence per 100,000 (ESR 2004)

% reported ( NZ Med J , 2000)

Cases per annum

Cost per case (1999 $)

Proportion waterborne

% hospitalised

% mortality (based on EPA data)

Average days off work

Time off work ($000)

Mortality ($000)

Medical ($000)

Total ($000)

Campylobacteriosis

3040

400

13%

121,600

$533

10%

0.3%

0.005%

5

$5,046

$1,216

$219

$6,481

E. coli O157 (VTEC)

9

3

35%

343

$60,000

20%

12.0%

0.4%

6

$34

$549

$3,532

$4,114

Cryptosporidiosis

200

20

10%

8,000

$978

30%

4.0%

0.02%

6

$1,195

$960

$192

$2,347

Giardiosis

250

25

10%

10,000

$855

20%

2.0%

0.02%

5

$830

$800

$80

$1,710

Salmonellosis

112

35

31%

4,480

$526

5%

1.0%

0.02%

3.5

$65

$90

$0

$118

Yersiniosis

62

12

20%

2,480

$891

10%

0.5%

 

9

$185

$0

$36

$221

Toxins (algae ...)

414

207

50%

16,560

$221

5%

0.3%

 

2

$137

$0

$46

$183

Virus (including hepatitis A)

478

72

15%

19,120

$204

2%

0.0%

0.002%

2

$63

$15

$0

$78

                   

$7,557

$3,629

$4,104

$15,253

Source: Adapted from Outcome Management Services Ltd, 2004.

Notes: This data is based on work published in the NZ Med J, 2000, V113 pp.278–84, Economic Cost to New Zealand of Food-borne Infectious Disease (Lake, Baker, Garrett, Scott, Scott) augmented with data from other sources as required:

  1. Annual Summary of Outbreaks in New Zealand, 2002, by ESR
  2. New Zealand Public Health surveillance Report Summer 2004
  3. www.cdc.gov (US Communicable Disease Unit)
  4. Information reviewed via personal communication with the Medical Officer of Health in MidCentral (Dr Donald Campbell)

Data modified from the above source is:

Cryptosporidiosis Time off-work estimated using Netherlands study: http://www.eurosurveillance.org/em/v01n02/0102-222.asp

Cost per case estimated six days off work/7 x $581/week income + $2 million x 0.0002(fatality risk) + $2000 x 0.04 (hospital risk mainly applies to children)

Giarida As above using five days off work since it is a less aggressive organism

E. coli 0157 % water-borne calculated using CDC reported outbreaks ex US (30%), modified for New Zealand. Under-reporting is estimated ONLY

$60,000/case is highly dependant on number of children with kidney failure needing long-term dialysis. Costs using Walkerton data = (seven deaths @ $2 million/case + 27 dialysis cases costing $150,000/annum for 30 years).

Salmonella Risk associated with roof-collection systems where poultry have access to roof collection systems or other vectors (animal or wind) are involved.

Under-reporting Derived from the study above based on an English infectious intestinal study. Protozoa values derived from US CDC experience.

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