Table 1.

Results of Leptospira spp. and SEOV diagnosed in cohorts of rats in four geographical regions in the Netherlands. Leptospira spp. results are based on combined results of culture and RT-PCR. The SEOV results are based on ELISA and RT-PCR of seropositive animals. Of the Nijmegen-Doetinchem study, all animals were tested by SEOV RT-PCR. Seropositive results for SEOV could not be confirmed by RT-PCR or a neutralization test, and were therefore considered negative.

		Leptospira spp.				SEOV
Study area	Number of brown rats tested	Nr. of positives/number tested (prevalence; 95% confidence interval)a	Culture positive/number tested	PCR positive/number tested	Serovar species (number)	Nr. of positives/number tested (prevalence; 95% confidence interval)	ELISA positives/number tested (average OD values of positive samples)	RT-PCR positives/number tested
1 Limburg	42 (34 in 2011, 8 in 2012)	14/42 (33%; 21–49%)	Not done	14/42	L. interrogans (3)b	0/42 (0%; 0–8%)	6/42 (2.4; 1.3; 0.9; 0.8; 1.9; 2.0)	0/6
2 Friesland	24 (7 in 2012, 17 in 2013)	8/24 (33%; 18–53%)	7/24	5/18	serovar Icterohaemorrhagiae (7) (serogroup Icterohaemorrhagiae)	0/24 (0%; 0–14%)	1/24 (0.8)	0/1
3 Amsterdam	31 (9 in 2014, 22 in 2015)	12/31 (39%; 24–56%)	12/31	10/31	serovar Icterohaemorrhagiae (6) and serovar Copenhageni (5) (serogroup Icterohaemorrhagiae)	0/31 (0%; 0–11%)	0/31	Not done
4 Nijmegen-Doetinchem	53 (2015)	30/53 (57%; 43–69%)	27/53	26/53	serovar Icterohaemorrhagiae (9/27) and serovar Copenhageni (18/27) (serogroup Icterohaemorrhagiae)	0/53 (0%; 0–7%)	3/53 (0.8;1.0;1.1)	0/53

^a Combined prevalence, culture and PCR results if available.

^b Three positive amplicons were further sequenced as being derived from L. interrogans.