TABLE 1.

Selected studies examining the prevalence of human colonic spirochetosis

Study	Reference	Detection method(s)a	Location(s)	Study population	Yr(s) of specimen collection	Specimen(s)	Total subjects	B. aalborgi positive	B. pilosicoli positive	Total HCS cases	Percent positive	Comments
Lee et al. (1971)	2	EM, HE, SS, PAS	Glasgow, Scotland, UK	Patients with diarrhea or suspected cancer	1961	Rectal biopsy specimen	144	—b	—	10	6.9	Includes the cases from Harland and Lee (3)
Lee et al. (1971)	2	EM, HE, SS, PAS	Glasgow, Scotland, UK	Appendectomy cases	1963–1966	Excised appendix	790	—	—	62	7.8	Included acute appendicitis (7/144 [4.4%]), “simulated” appendicitis (15/523 [9.8%]), incidental appendectomy (4/107 [4.4%])
McMillan and Lee (1981)	11	HE	Glasgow, Scotland, UK	MSMc	NId	Colorectal biopsy specimen; FFPEe	100	—	—	36	36.0
McMillan and Lee (1981)	11	HE	Glasgow, Scotland, UK	Heterosexual men	NI	Colorectal biopsy specimen; FFPE	67	—	—	2	3.0
Mathan and Mathan (1985)	26	EM	Southern India	Healthy adults	NI	Rectal biopsy specimen	14	—	—	9	64.3
Cooper et al. (1986)	27	EM	Southhampton, Hampshire, England, UK	MSM	NI	Rectal biopsy specimen	8	—	—	5	62.5	Reduction in microvillus density observed
Cooper et al. (1986)	27	EM	Southhampton, Hampshire, England, UK	Heterosexual men	NI	Rectal biopsy specimen	5	—	—	0	0.0
Surawicz et al. (1986)	28	HE, AB, SS	Seattle, WA	MSM	NI	Rectal biopsy specimen	100	—	—	28	28.0
Tompkins et al. (1986)	29	C	Great Britain, UK	Healthy adults	NI	Colorectal biopsy specimen	1,527	—	—	23	1.5	All positive specimens from either MSM or persons of Asian ethnicity
Barrett (1990)	30	C	Muskat Region, Oman	Healthy children and adults	1988	Feces	292	—	—	78	26.7
Barrett (1990)	30	C	Muskat Region, Oman	Hospitalized patients	1988	Feces	1,000	—	—	114	11.4
Lee and Hampson (1992)	12	C	Western Australia	Aboriginal children and adults	1989–1991	Feces	181	—	—	59	32.6	Isolates were shown subsequently to be B. pilosicoli (31)
Lee and Hampson (1992)	12	C	Western Australia, Northern Territory	Non-Aboriginal children and adults	1989–1991	Feces	695	—	—	8	1.2
De Brito et al. (1996)	32	HE, SS, IHC, EM	Brazil	Patients with GIf symptoms	NI	Rectal and sigmoidal colonic biopsy specimens	282	—	—	4	1.4
Trivett-Moore et al. (1998)	13	HE, EM, C	Sydney, Australia	MSM attending a sexual health clinic	NI	Rectal biopsy specimens	41	(0)	(13)	22	53.7	B. pilosicoli isolated from biopsy samples positive (11/22) and negative (2/19) for HCS by HE and EM
Brooke et al. (2001)	10	C	Western Australia	Aboriginal rural patients with GI complaints	1998–1999	Feces	151	0	15	15	9.9	High proportion of isolates from subjects aged 2 to 5
Brooke et al. (2001)	10	C	Western Australia	Non-Aboriginal rural patients with GI complaints	1998–1999	Feces	142	0	0	0	0
Brooke et al. (2001)	10	C	Australia	Entering migrants to Australia	1998–1999	Feces	227	0	24	24	10.6	Isolates/subjects for migrants from Asia (2/8), Eastern Europe (3/94), the Middle East (9/65), and Africa (10/50)
Margawani et al. (2004)	33	C	Bali, Indonesia	Adult and child residents	1999	Feces (August)	500	0	59	59	11.8	375 subjects were sampled at both time points
Margawani et al. (2004)	33	C	Bali, Indonesia	Adult and child residents	1999	Feces (December)	492	0	62	62	12.6	375 subjects were sampled at both time points
Esteve et al. (2006)	16	HE, SS, PAS, PCR	Barcelona, Spain	Patients with chronic watery diarrhea and control subjects	1994–2004	Colonic biopsy samples	1,176	(2)	(2)	8	0.7	Of 8 subjects positive for HCS by light microscopy, 2 were positive for B. pilosicoli and 2 for B. aalborgi by PCR
Calderaro et al. (2007)	34	PCR, C	Parma, Italy	Patients with suspected gastrointestinal infections	2002–2006	Feces, colonic biopsy samples, FFPE	234	13	5	16	6.8	Two patients were coinfected with B. aalborgi and B. pilosicoli
Tanahashi et al. (2008)	35	HE, SS, IHC, immuno-EM, PCR	Oita, Japan	Patients with colonoscopy or surgical resections	2005–2006	Colonic biopsy samples, FFPE	2,556	20	3	20	0.8	11 cases identified by HE, SS, and IHC. 20 cases positive for B. aalborgi by PCR; 3 cases also positive for B. pilosicoli
Ichimata et al. (2017)	36	HE	Asahi, Matsumoto, Japan	Patients <20 yrs of age with gastrointestinal symptoms	NI	Biopsy specimens, surgical specimens	479	—	—	1	0.2
Thorell et al. (2019)	8	HE, IHC, SS, C	Sweden	Adult population	2000–2006	Biopsy samples of terminal ileum and colon from cecum to rectum (5 sites)	745	13	1	17	2.3	HCS cases correspond to those described previously by Walker et al. (18); 3 subjects who were positive by HE, IHC, and SS positive were negative by culture
Mikosza et al. (2001)	37	PCR	Australia	HCS subjects (by HE)	NI	Colon, colorectal, cecum, and appendix biopsy samples; FFPEb	28	24	4	26	92.9	2 subjects were positive for both B. aalborgi and B. pilosicoli; 2 subjects were negative by PCR
Mikosza et al. (2004)	38	PCR	Australia (20); USA (1); France (1); Norway (2)	HCS subjects (by HE)	NI	Colon, colorectal, cecum, and appendix biopsy samples; PET	24	22	2	24	100	Prescreened for intestinal spirochetosis by histology
Westerman et al. (2012)	39	Real-time PCR	The Netherlands	HCS subjects (by HE, IHC)	2001–2011	Colon biopsy samples; FFPE	56	48	9	56	100	Several genotypesg
Rojas et al. (2017)	40	FISH	Germany	HCS subjects (by HE)	NI	Intestinal biopsy samples (from ileum to rectum); PET	91	—	—	77	84.6	Prescreened for intestinal spirochetosis by histology; same specimens were analyzed by both FISH and PCR
Rojas et al. (2017)	40	PCR	Germany	HCS subjects (by HE)	NI	Intestinal biopsy samples (from ileum to rectum); PET	91	53	23	75	82.4	Prescreened for intestinal spirochetosis by histology; includes one subject with both B. aalborgi and B. pilosicoli

^aIn the studies described in references 37 to 40, specimens were prescreened for colonic spirochetosis. Abbreviations: AB, alcian blue-stained sections; C, culture; EM, transmission electron microscopy; FISH, fluorescent in situ hybridization; HE, hematoxylin and eosin-stained sections; IHC, immunohistochemistry; PAS, periodic acid-Schiff-stained sections; SS, silver-stained sections.

^b—, species not determined.

^cMSM, men who have sex with men.

^dNI, not indicated.

^eFFPE, formalin-fixed, paraffin-embedded tissue.

^fGI, gastrointestinal.

^gIncludes 36 B. aalborgi cluster 1 organisms alone, 6 B. aalborgi cluster 2 (“B. hominis”) organisms alone, 6 B. pilosicoli organisms alone, 5 cluster 1 and cluster 2 organisms, 1 B. pilosicoli and cluster 2 organisms, and 2 B. pilosicoli, cluster 1, and cluster 2 organisms (triple positive).