Gastrointestinal & Zoonoses

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Gastrointestinal & Zoonoses

Weekly Report Articles

19 September 2017

Incidence of protozoal infection reported to HPS in 2016


In 2016, HPS received 786 laboratory reports of Cryptosporidium (Figure 1). This represents an increase of 63 (8.7 %) on 2015 when there were 723 reports, and also an increase on the average number of cases over the previous ten years (2006-2015) of 581 cases per annum. However the incidence in 2016 is lower than that reported in 2000 and 2003, with over 800 reports in either year. The reports in 2016 reflect the year-on-year variation observed in the annual totals for Cryptosporidium. In the first 34 weeks of 2017, there have been 302 reports of Cryptosporidium, a decline of 113 (27%) compared to the corresponding period last year when there were 415 reports, again reflecting this year-on-year variation.

Since 2011 a proportion of all isolates are speciated each year by the Scottish Parasite Diagnostic and Reference Laboratory, in addition to any isolates thought to be associated with an incident or outbreak. Of the 786 reports of Cryptosporidium in 2016, 379 (48%) were speciated, with 200 (53%) being identified as Cryptosporidium parvum and 179 (47%) as Cryptosporidium hominis. This is a slightly lower proportion of C. parvum and correspondingly higher proportion of C. hominis than the proportions in both 2015 and 2014 of approximately 60% C. parvum and 40% C. hominis.

Reports of Cryptosporidium show two peaks during the year, the first in the spring being mainly due to cases of C. parvum, and the second peak in the autumn due to both C. hominis and C. parvum, conforming to expected seasonal trends.


HPS received 231 laboratory reports of Giardia in 2016 (Figure 3), an increase of 36 (18.5%) compared to the 195 reports in 2015. This is the second consecutive year reports have increased and follows a general downward trend between 2007 and 2013. The number of reports in 2016 is similar to 2007 and 2008 when there were 223 and 221 respectively.

Some of the increase in reports observed over the past two years is likely to be due to changes in the diagnostic techniques used in some of the laboratories.

Cyclospora cayatanensis

Cyclospora cayetanensis is a protozoon that infects humans and other primates. Infection can cause frequent, watery diarrhoea, abdominal cramping, bloating, nausea, flatulence, low-grade fever, loss of appetite and weight. Individuals with underlying immune deficiency can be at risk of more severe disease. Infection is commonly derived from food or water contaminated by human faeces and there is no evidence of zoonotic transmission. The foods commonly associated with Cyclospora infection include soft fruits such as raspberries and salad products such as lettuce and coriander.

A total of 167 laboratory reports of Cyclospora were received by HPS in 2016, compared to 24 in 2015 and just two in 2015. The increases in both 2015 and 2016 were associated with outbreaks among travellers returning from Mexico during the summer months. More information on these outbreaks is available at and While some cases of Cyclospora have been reported in travellers returning from Mexico during the summer of 2017, the numbers have been lower than in 2016.

General information on the Cyclospora risk for travellers to Mexico and general food and water precautions are available on the fit for travel website: and

Images (click on thumbnail to view).

eWeeklyReport Table eWeeklyReport Table eWeeklyReport Table

Author(s): Prepared by: GIZ team Vol: 51 No: 37 Year: 2017 Page: