Authors

B Carter⁴; R E Stiff²; B Mason³; H Hutchings⁴; A P Davies⁴; R M Chalmers¹;  ¹ Cryptosporidium Reference Unit, Swansea, UK;  ² Health Protection, Public Health Wales NHS Trust, UK;  ³ Public Health Wales Carmarthenshire, Wales, UK;  ⁴ Swansea University Medical School, UK

Discussion

Introduction: Cryptosporidium is the most common protozoal cause of acute gastroenteritis in the UK with between 3,500 and 5,500 laboratory-confirmed cases reported annually in England and Wales from 2013 to 2015. Cryptosporidiosis in immunocompetent patients is characterized by gastrointestinal symptoms that include a sudden-onset, profuse, watery diarrhoea which may be accompanied by abdominal pain or cramps, vomiting and weight loss. Other, more non-specific symptoms include malaise, fatigue, fever, nausea and muscle weakness.

More than 90% of human cryptosporidiosis cases in developed countries can be attributed to just two Cryptosporidium species; Cryptosporidium parvum, a zoonotic species, and Cryptosporidium hominis, an anthroponotic species.

Relatively little is known about the longer term health effects of Cryptosporidium infection, with some potential sequelae identified and substantiated by solitary case reports. However, there is growing evidence to suggest that, rather like some bacterial causes of gastroenteritis, Cryptosporidium infection may have long-term consequences.

Aims To investigate long-term health sequelae after resolution of acute cryptosporidiosis. Methods This was a prospective study of cases aged >6 months old and resident in Wales, with laboratory confirmed cryptosporidiosis, genotyped at the Cryptosporidium Reference Unit, Swansea between July 2013 - July 2015. Participants self-reported symptoms, and clinician-diagnosed conditions, at three time points: within 2 weeks of laboratory diagnosis (baseline), at 3 months, and 12 months. To identify cases with symptoms consistent with irritable bowel syndrome (IBS) specifically, the standard Rome III criteria were used. Results Over the two-year recruitment period, 515 cases were contacted by our study team, 52% of which were < 18 years old. The predominant Cryptosporidium species identified was C. parvum (n≤300) followed by C. hominis (n≤200), C. cuniculus (n≤9), C. felis (n≤3), C. hominis & C. parvum (n≤2) and C. ubiquitum (n≤1). At baseline, 205 patients (40%) agreed to participate in our study. Long-term sequelae analysis was performed on 89 complete data sets (i.e. baseline, 3 month and 12 month questionnaires all returned).
In the 12-month follow up period, 6 participants (8%) developed Irritable Bowel Syndrome (IBS) according to Rome III criteria, while 34 participants (44%) reported IBS-like symptoms. Statistically significant new symptoms self-reported up to 12 months post-infection included: fatigue (35%), abdominal pain (25%), nausea (24 %), headache (24%), loss of appetite (21%), joint pain (21%), blurred vision (13%) and eye pain (10%).
In the 12 months following resolution of acute illness, the self-reported symptoms nausea (RR: 0.07, 95% CI: 0.02 - 1.04, p ≤ 0.05), abdominal pain (RR: 0.60, 95% CI: 0.06 - 6.44, p ≤ 0.99), loss of appetite (RR: 0.89, 95% CI: 0.11 - 7.20, p ≤ 0.99), fatigue (RR: 0.59, 95% CI: 0.20 - 1.69, p ≤ 0.42), blurred vision (RR: 0.60, 95% CI: 0.18 - 2.05, p ≤ 0.48) and eye pain (RR: 0.87, 95% CI: 0.21 - 3.56, p ≤ 0.99) were less likely to be reported following Cryptosporidium parvum infection than Cryptosporidium hominis infection. Joint pain was more likely to be reported following C. parvum infection (RR: 4, 95% CI: 0.56 - 30.19, p ≤ 0.14). However, none of these species differences were statistically significant.