More cryptosporidiosis outbreaks could be on the cards for Aotearoa New Zealand as extreme rainfall events become more frequent, causing higher levels of the diarrhea-causing parasite to be washed into waterways, public health researchers warn. The researchers studied clusters of cryptosporidium outbreaks around the country between 1997 and 2015 and found 13 coincided with severe weather events. Their research is published in the journal Epidemiology & Infection .
It is the first study to compare clusters of outbreaks of cryptosporidiosis to severe weather events in Aotearoa. One of the researchers, Professor Simon Hales from the Department of Public Health at the University of Otago, Wellington, says the study found 38 "statistically significant" clusters, unlikely to have occurred by chance. The 13 that coincided with severe weather events included 55 cases that occurred after heavy rain in Kaikoura in March 1999 and 22 cases following a countrywide weather bomb in October 2000.
Professor Hales says runoff from livestock is likely to be heightening the risk of disease outbreaks. Nearly half of the 13 clusters that aligned with severe weather events occurred in the spring, suggesting a link to calving and lambing times, with newborn livestock a known source of the parasite. Cryptosporidium is one of the most common causes of waterborne gastrointestinal illness, with almost 16,000 cases of cryptosporidiosis notified in Aotearoa between 1997 and 2015.
Most people are infected .
