After the entire California set and completely gone to ... hell, testing revealed giardia in the surrounding area.
The giardia parasite, which can live in the gut of humans or animals, can be spread from faecal contamination of food or water or by person-to-person contact. Symptoms of infection, which can be treated with drugs, include violent diarrhoea and intestinal cramps.
Infections in New Zealand usually peak in late summer and early autumn.
New Zealand has one of the highest rates of the disease in the developed world, due to the proportion of the population that live in rural settings.
Children under four are most likely to be affected by giardia, which can be treated with anti-microbial tablets. Symptoms include chronic diarrhoea, abdominal cramps, bloating, nausea and fatigue.