Estimating trematode prevalence in snail hosts using a single-step duplex PCR: how badly does cercarial shedding underestimate infection rates?

Table 2 Prevalence of infections detected by the classical detection method and the duplex PCR detection method

		Total no. snails	Infection	No. infected Emission	Prevalence (%) Emission	No. infected duplex PCR	Prevalence (%) duplex PCR	% infections that failed detection by emission
Ebro samples	2011	89	C. labracis	31	34.8	38	42.7	18.4
			M. obovata	21	23.6	22	24.7	4.5
			Double infection	6	6.7	14	15.7	57.1
			Total 2011 infected	58	65.2	74	83.1	21.6
	2013	168	C. labracis	45	26.8	136	81	66.9
			M. obovata	12	7.1	6	3.6	-1
			Double infection	4	2.4	20	11.9	80
			Total 2013 infected	61	36.3	162	96.4	62.3
Otago samples	LP	161	M. novaezealandensis	81	50.3	91	56.5	11
			Philophthalmus sp.	10	6.2	11	6.8	9.1
			Double infection	7	4.3	12	7.5	41.6
			Total LP infected	98	60.9	114	70.8	14.0
	OB	126	M. novaezealandensis	62	49.2	82	65.1	24.4
			Philophthalmus sp.	3	2.4	6	4.8	50
			Double infection	1	0.8	4	3.2	75
			Total OB infected	66	52.4	92	73.0	28.3

Prevalence and numbers of infections detected based on the classical method (emission of parasites) and the duplex PCR method. i) Ebro samples: C. labracis, M. obovata and double infections in G. adansonii, from the Ebro Delta (Spain), years 2011 and 2013; and ii) Otago samples: M. novaezealandensis, Philophthalmus sp. and double infections in Z. subcarinatus, from Otago Habour (New Zealand), sampling sites (LP: Lower Portobello Bay, OB: Oyster Bay). Percentage infections not detected by emission = (no. infected duplex PCR minus no. infected classical method) / no. infected duplex PCR.

ISSN: 1756-3305