Assessing rates of parasite coinfection and spatiotemporal strain
variation via metabarcoding: insights for the conservation of European
Turtle Doves Streptopelia turtur
Understanding the frequency, spatiotemporal dynamics and impacts of
parasite coinfections is fundamental to developing control measures and
predicting disease impacts. The European turtle dove (Streptopelia
turtur) is one of Europe’s most threatened bird species. High prevalence
of infection by the protozoan parasite Trichomonas gallinae has
previously been identified, but the role of this and other coinfecting
parasites in turtle dove declines remains unclear. Using a
high-throughput sequencing approach, we identified seven strains of T.
gallinae, including two novel strains, from ITS1/5.8S/ITS2 ribosomal
sequences in turtle doves on breeding and wintering grounds, with
further intra-strain variation and four novel sub-types revealed by the
iron-hydrogenase gene. High spatiotemporal turnover was observed in T.
gallinae strain composition, and infection was prevalent in all
populations (89–100%). Coinfection by multiple Trichomonas strains was
rarer than expected (1% observed compared to 38.6% expected),
suggesting either within-host competition, or high mortality of
coinfected individuals. In contrast, coinfection by multiple
haemosporidians was common (43%), as was coinfection by haemosporidians
and T. gallinae (90%), with positive associations between strains of T.
gallinae and Leucocytozoon suggesting a mechanism such as
parasite-induced immune modulation. We found no evidence for negative
associations between coinfections and host body condition. We suggest
that longitudinal studies involving the recapture and investigation of
infection status of individuals over their lifespan are crucial to
understand the epidemiology of coinfections in natural populations.