Source: RNZ, 17 August 2016
The campylobacter outbreak in Havelock North is one of the
biggest single instances of waterborne disease in New Zealand
history - but it's not yet the worst.
That dubious distinction goes to Queenstown where, in 1984, an
estimated 3500 people had gastroenteritis after the town's water
supply was contaminated by raw sewage.
The cause? A brick.
"Lake County Council's senior health inspector, Mr Colin Walker,
said a brick blocked a sewer in dense bush, causing the sewer to
overflow into a small creek which ran into Lake Wakatipu,"The
Evening Postreported on November 2, 1984.
"The town's water was drawn less than 150 metres from where the
contaminated creek water entered the lake."
Queenstown's reservoirs were partly-drained and the town water
supply was heavily chlorinated for months afterwards.
Invercargill's medical officer of health at the time, Ingrid
Seeman, described the illness to reporters as "acute but mild".
"Nobody went into hospital. Some residents and visitors
consulted the local doctor but a lot of people coped with it
Later, the local council was told it was "lucky" no one had
Havelock North has not been as lucky.
There are 22 people in hospital, two of them in a critical
condition in intensive care.
Health officials were waiting for test results to confirm
whether a person who died at a rest home from a gastro-like illness
was a victim of the outbreak.
18,000 cases of waterborne illness a year
Otago University public health researcher Michael Baker says
barring Queenstown, Havelock North is "by far the largest" outbreak
of waterborne disease recorded in New Zealand.
"I don't know of anything else on this scale ... There's a very
good reason why huge investment has gone into making water
But while huge outbreaks are rare, waterborne disease is far
more common in New Zealand than might be expected.
Health Ministry documents and news reports show the last three
decades have been peppered with smaller, less serious
Cardrona township's water supply has twice fallen victim to
In 2006, 218 skiers and resort staff caught the bug after
overflow from a septic tank contaminated drinking water.
Then in 2012, at least 53 people were infected - a report into
the outbreak concluded the supply was contaminated through a
combination of inadequate chlorination and surface flooding.
roll-call of outbreaks published in a 2006 Environmental
Science and Research (ESR) report includes:
- Auckland, 1993 - 34 cases of giardia
- Ashburton, 1996 - 33 cases of campylobacter
- Waikato, 1997 - 170 cases of cryptosporidium
- Te Aute College, Hawkes Bay, 2001 - 137 cases of
The ESR report found an average of 17 common-source outbreaks a
year, with an average total of 145 people affected.
But the report - and
Ministry for the Environment figures - estimated an eye-popping
18,000 cases of waterborne illness in New Zealand every year,
including 12,000 cases of waterborne campylobacter and another 2400
cases of cryptosporidium.
There's a vast gulf between 145 cases and 18,000 cases - so
where does the difference come from?
The additional thousands of cases are what Dr Baker describes as
"sporadic" - people who have become sick without it being linked to
a particular outbreak.
About 85 percent of the population had access to water that was
very good quality, but it was difficult to get safe water to the
entire population, Mr Baker said.
The ESR report said an estimated 460,000 people - 10 percent of
the population - were dependent on rainwater collection or other
unregistered water supplies.
"[It's] mainly smaller supplies that for all sorts of reasons
aren't covered - you think of all the small, informal settlements,
and baches with roof collection and so on," Dr Baker said.
Documenting outbreaks was important, he said.
"The great thing about outbreaks is that more effort goes into
identifying sources ... and that may represent where a lot of
sporadic disease is coming from."