Increase of avian Plasmodium circumflexum prevalence, but not of other malaria parasites and related haemosporidians in northern Europe during the past 40 years

Table 1 Prevalence of avian malaria parasites (Plasmodium) and related haemosporidians in passeriform birds migrating to wintering grounds from their breeding sites located between the White Sea and the Baltic Sea, northern Europe.

Bird family, bird species and parasites	Bird group, study site and period of sampling				Difference, p-value ^a
	Group 1, Curonian Spit, September 1979–1983		Group 2, Ventes Ragas peninsular, September 2020
	No. examined	No. infected ^b	No. examined	No. infected ^b
Muscicapidae
Erithacus rubecula ^c	33	4 (12.1)	40	3 (7.5)	0.04 (0.8350)
Infected with:
Haemoproteus sp.		1 (3.0)		1 (2.5)	0.34 (0.5582)
Plasmodium sp.		1 (3.0)		1 (2.5)	0.34 (0.5582)
Leucocytozoon sp.		2 (6.1)		1 (2.5)	0.02 (0.8887)
Paridae
Periparus ater ^d	60	3 (5.0)	40	25 (62.5)	19.33 (0.0000)
Infected with:
Haemoproteus sp.		3 (5.0)		7 (17.5)	2,23 (0. 1354)
Plasmodium sp.		0		18 (45.0)	19.64 (0.0000)
Leucocytozoon sp.		0		0	0 ^e
Parus major ^c	39	13 (33.3)	40	27 (67.5)	2.42 (0.1195)
Infected with:
Haemoproteus sp.		7 (17.9)		10 (25.0)	0.12 (0. 7296)
Plasmodium sp.		2 (5.1)		15 (37.5)	6.62 (0.0101)
Leucocytozoon sp.		4 (10.2)		2 (5.0)	0.15 (0.6939)
Troglodytidae
Troglodytes troglodytes ^d	17	0	40	17 (42.5)	5.00 (0.0253)
Infected with:
Haemoproteus sp.		0		0	0 ^e
Plasmodium sp.		0		17 (42.5)	5.00 (0.0253)
Leucocytozoon sp.		0		0	0 ^e
Corvidae
Garrulus glandarius ^d	30	12 (40.0)	29	16 (55.2)	0.22 (0.6404)
Infected with:
Haemoproteus sp.		2 (6.7)		6 (20.7)	0.99 (0.3191)
Plasmodium sp.		0		4 (13.8)	2.11 (0.1462)
Leucocytozoon sp.		11 (36.7)		6 (20.7)	0.54 (0.4630)
Total infected with
Haemoproteus sp.		13 (7.3)		24 (12.7)	1.95 (0.1628)
Plasmodium sp.		3 (1.7)		55 (29.1)	36.99 (0.0000)
Leucocytozoon sp.		17 (9.5)		9 (4.8)	2,09 (0.1478)
Grant total	179	33 (18.4)	189	83 (46.6)	16.07 (0.0001)

The birds were sampled on the coast of the Curonian Lagoon at two close study sites (Curonian Spit and Ventė Cape, see Fig. 1). Only data of microscopic examination of blood films was given
^aYates-corrected Chi-squire test value, followed in parenthesis by the corresponding significance P-value. Significant differences were shown in bold
^bNumber of infected birds, followed in parenthesis by prevalence of infection (in percentage)
^cOnly juvenile birds were samples
^dBird age was not identified. During autumnal migration, the juvenile birds predominate in all bird species, and likely predominated during this study, but the presence of some adult individuals cannot be ruled out in both sampled periods
^eParasites were not reported in both groups

ISSN: 1475-2875