Effects of malaria double infection in birds: one plus one is not two

Abstract

Avian malaria parasites are supposed to exert negative effects on host fitness because these intracellular parasites affect host metabolism. Recent advances in molecular genotyping and microscopy have revealed that coinfections with multiple parasites are frequent in bird–malaria parasite systems. However, studies of the fitness consequences of such double infections are scarce and inconclusive. We tested if the infection with two malaria parasite lineages has more negative effects than single infection using 6 years of data from a natural population of house martins. Survival was negatively affected by both types of infections. We found an additive cost from single to double infection in body condition, but not in reproductive parameters (double‐infected had higher reproductive success). These results demonstrate that malaria infections decrease survival, but also have different consequences on the breeding performance of single‐ and double‐infected wild birds.

Cost of co-infection controlled by infectious dose combinations and food availability

“…Co-infection by several parasite species (also called polyparasitism) can substantially modify the detrimental eVects that each parasite alone would have on its host (Bonsall and Benmayor 2005;Cox 2001;Marzal et al 2008). Depending on the host and parasite species and the experimental setup, the presence of a second parasite can increase the host's Wtness, decrease it or leave it unchanged relative to what would be expected if the detrimental eVects of each parasite alone were simply accumulated (Cox 2001;Marzal et al 2008;Pullan and Brooker 2008).…”

“…Co-infection by several parasite species (also called polyparasitism) can substantially modify the detrimental eVects that each parasite alone would have on its host (Bonsall and Benmayor 2005;Cox 2001;Marzal et al 2008). Depending on the host and parasite species and the experimental setup, the presence of a second parasite can increase the host's Wtness, decrease it or leave it unchanged relative to what would be expected if the detrimental eVects of each parasite alone were simply accumulated (Cox 2001;Marzal et al 2008;Pullan and Brooker 2008). When virulence (generally expressed as parasite-induced mortality) relates to parasite transmission, the eVects of co-infection on virulence are thought to have considerable inXuence on virulence evolution (Brown et al 2002;de Roode et al 2005;Frank 1992;Gower and Webster 2005;Van Baalen and Sabelis 1995).…”

Genetic diversity of avian blood parasites in SE Europe: Cytochrome b lineages of the genera Plasmodium and Haemoproteus (Haemosporida) from Bulgaria

“…lineages recorded in only one host species (Table II). DURB4 has previously been found in house martins (Delichon urbicum) (Marzal et al 2008), which is a long-distance migrant. However, in the present study, we found the same lineage in the tree sparrow, a resident species in the temperate zone indicating a local transmission of this lineage.…”

Nest-climatic factors affect the abundance of biting flies and their effects on nestling condition

“…Moreover, black fly saliva produces an (Bennett, 1961;Valkiūnas, 2005). These blood parasites infect pied flycatcher nestlings in central Spain (Merino and Potti, 1995;Lobato et al, 2005) and multiple infections could be more virulent than single ones (Marzal et al, 2008;del Cerro et al, 2010). Obviously, the effects of the interaction between vectors and parasites on birds merit further studies.…”