Outbreak of Diarrhea Caused by a Novel Cryptosporidium hominis Subtype During British Military Training in Kenya

Romeo Toriro; Scott Pallett; Stephen Woolley; Charlie Bennett; Isra Hale; Jennifer Heylings; Daniel Wilkins; Thomas Connelly; Kennedy Muia; Patrick Avery; Andrew Stuart; Laura Morgan; Mark Davies; William Nevin; Oliver Quantick; Guy Robinson; Kristin Elwin; Rachel Chalmers; Daniel Burns; Nicholas Beeching; Thomas Fletcher; Matthew O'Shea

doi:10.1093/ofid/ofae001

Outbreak of Diarrhea Caused by a Novel Cryptosporidium hominis Subtype During British Military Training in Kenya

Open Forum Infect Dis. 2024 Jan 3;11(1):ofae001. doi: 10.1093/ofid/ofae001. eCollection 2024 Jan.

Authors

Romeo Toriro^{1

2}, Scott Pallett³, Stephen Woolley^{2

3}, Charlie Bennett³, Isra Hale⁴, Jennifer Heylings⁵, Daniel Wilkins⁶, Thomas Connelly⁷, Kennedy Muia⁸, Patrick Avery⁹, Andrew Stuart⁹, Laura Morgan¹⁰, Mark Davies⁸, William Nevin², Oliver Quantick¹¹, Guy Robinson^{12

13}, Kristin Elwin¹², Rachel Chalmers^{12

13}, Daniel Burns¹⁴, Nicholas Beeching², Thomas Fletcher^{2

14}, Matthew O'Shea^{3

15}

Affiliations

¹ Army Medical Services, Robertson House, Royal Military Academy Sandhurst, Camberley, Surrey, UK.
² Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, Merseyside, UK.
³ Centre of Defence Pathology, Royal Centre for Defence Medicine, Queen Elizabeth Hospital Birmingham, Birmingham, UK.
⁴ 3 Medical Regiment, Fulwood Barracks, Preston, Lancashire, UK.
⁵ 28 (C-CBRN) Engineer Regiment, Rock Barracks, Woodbridge, Suffolk, UK.
⁶ 2nd Battalion the Rifles, Thiepval Barracks, Lisburn, UK.
⁷ 29 Public Health Division Medical Group, HQ 3 (UK) Division, Bulford, Wiltshire, UK.
⁸ British Army Training Unit (Kenya), Nanyuki, Kenya.
⁹ Defence Primary Healthcare, Medical Centre, Nanyuki, Kenya.
¹⁰ HQ 1st (UK) Division, Imphal Barracks, York, Yorkshire, UK.
¹¹ Army Health, Army Headquarters, Andover, Hampshire, UK.
¹² Cryptosporidium Reference Unit, Public Health Wales Microbiology, Singleton Hospital, Sketty, Swansea, Wales, UK.
¹³ Swansea University Medical School, Swansea, Wales, UK.
¹⁴ Royal Centre for Defence Medicine, Birmingham, UK.
¹⁵ Institute of Immunology and Immunotherapy, College of Medical & Dental Sciences, University of Birmingham, Birmingham, UK.

Abstract

Background: We report clinical, epidemiological, and laboratory features of a large diarrhea outbreak caused by a novel Cryptosporidium hominis subtype during British military training in Kenya between February and April 2022.

Methods: Data were collated from diarrhea cases, and fecal samples were analyzed on site using the multiplex polymerase chain reaction (PCR) BioFire FilmArray. Water was tested using Colilert kits (IDEXX, UK). DNA was extracted from feces for molecular characterization of Cryptosporidium A135, Lib13, ssu rRNA, and gp60 genes.

Results: One hundred seventy-two of 1200 (14.3%) personnel at risk developed diarrhea over 69 days. One hundred six primary fecal samples were tested, and 63/106 (59.4%; 95% CI, 0.49%-0.69%) were positive for Cryptosporidium spp. Thirty-eight had Cryptosporidium spp. alone, and 25 had Cryptosporidium spp. with ≥1 other pathogen. A further 27/106 (25.5%; 95% CI, 0.18%-0.35%) had non-Cryptosporidium pathogens only, and 16/106 (15.1%; 95% CI, 0.09%-0.23%) were negative. C. hominis was detected in 58/63 (92.1%) Cryptosporidium spp.-positive primary samples, but the others were not genotypable. Twenty-seven C. hominis specimens were subtypable; 1 was gp60 subtype IeA11G3T3, and 26 were an unusual subtype, ImA13G1 (GenBank accession OP699729), supporting epidemiological evidence suggesting a point source outbreak from contaminated swimming water. Diarrhea persisted for a mean (SD) of 7.6 (4.6) days in Cryptosporidium spp. cases compared with 2.3 (0.9) days in non-Cryptosporidium cases (P = .001).

Conclusions: Real-time multiplex PCR fecal testing was vital in managing this large cryptosporidiosis outbreak. The etiology of a rare C. hominis gp60 subtype emphasizes the need for more genotypic surveillance to identify widening host and geographic ranges of novel C. hominis subtypes.

Keywords: Cryptosporidium; DNA extraction and speciation; diarrhea; military population; outbreak.