Cryptosporidiosis There were 310 cryptosporidiosis cases notified in 2014, which was the fourth most common notifiable enteric disease. The notification rate (12.2 cases per 100 000 population) was consistent with the mean of the previous five years (11.5 cases per 100 000 population) (Appendix 1). In each of the years from 2009 to 2014 cryptosporidiosis case numbers were higher in the late summer through to autumn (Figure 13). An increase in cases in November was due, in part, to a swimming pool associated outbreak of Cryptosporidium (see section 5.2). Figure 13. Number of cases of cryptosporidiosis by year and month of onset, WA, 2009 to 2014 The cryptosporidiosis notification rate was 20% higher in females than males in 2014 (13.4 and 11.1 per 100 000 population, respectively). The <1- 4 years age group had the highest notification rate (66 per 100 000 population), and accounted for 37% of all cryptosporidiosis notifications (Figure 14). The overall notification rate for the Aboriginal population was 4.5 times the rate for the non-Aboriginal population (46.7 and 10.4 cases per 100 000 population, respectively). The region had the highest notification rate (64 cases per 100 000 population), and the Great Southern region the lowest notification rate (10 cases per 100 000 population) (Figure 15). Of those cryptosporidiosis cases with known place of acquisition, most (87%) people acquire their illness in WA with 12% of people acquiring their illness overseas. Figure 14. Age-specific notification rates for cryptosporidiosis by sex, WA, 2014 Figure 15. Cryptosporidiosis notification rates by region and Aboriginality, WA, 2014
outbreaks each and Cyclospora species caused one outbreak. Fifteen outbreaks were caused by unknown pathogens. Food vehicles The investigations of the 13 outbreaks identified food vehicles for seven outbreaks. The Salmonella Typhimurium PFGE 0001 outbreaks were associated with eating lamb shanks and pork hocks and one of the Salmonella Infantis outbreaks was associated with eating nasi-lemak. Two norovirus outbreaks were associated with eating salads. One outbreak each was associated with the following foods: roast meats (suspected toxin mediated) and multiple foods (unknown pathogen). In the previous five years there were 66 foodborne or suspected foodborne outbreaks and food vehicles were identified for 31 (47%) outbreaks. Of these 31 outbreaks, the most commonly implicated foods were dishes containing eggs in nine outbreaks, chicken in five outbreaks, fresh produce in six outbreaks, eight outbreaks implicating a range of dishes, and multiple dishes in three outbreaks. Of the 35 outbreaks with unknown food vehicles, the aetiological agents included Salmonella (n=14), norovirus (n=7), Campylobacter (n=1), Cyclospora (n=1), Clostridium perfringens (n=2) and unknown aetiology (n=10). Epidemiological investigation and evidence The evidence that supported that the 13 investigations of enteric outbreaks were due to foodborne or suspected foodborne transmission was obtained using analytical studies for six outbreaks and descriptive cases series (DCS) for seven outbreaks. The analytical studies involved interviewing those people who were at the meal using a questionnaire on all foods/drinks available. For the outbreaks investigated as a DCS, there was strong circumstantial evidence to support suspected foodborne transmission including ill people eating a common meal (4 outbreaks) or visiting a common food business (3 outbreaks). For the previous five years the evidence used to support that 66 outbreaks were due to foodborne transmission was obtained using analytical studies for 22 (33%) outbreaks and seven outbreaks found an association between illness and a food. There were 42 (64%) outbreaks investigated as DCS. No formal study was carried out for two outbreaks.