Dataset Information

Seasonal dynamics of haemosporidian (Apicomplexa, Haemosporida) parasites in house sparrows Passer domesticus at four European sites: comparison between lineages and the importance of screening methods.

ABSTRACT: Infectious diseases often vary seasonally in a predictable manner, and seasonality may be responsible for geographical differences in prevalence. In temperate regions, vector-borne parasites such as malaria are expected to evolve lower virulence and a time-varying strategy to invest more in transmission when vectors are available. A previous model of seasonal variation of avian malaria described a double peak in prevalence of Plasmodium parasites in multiple hosts resulting from spring relapses and transmission to susceptible individuals in summer. However, this model was rejected by a study describing different patterns of seasonal variation of two Plasmodium spp. at the same site, with the double peak only apparent when these species were combined. Here, we assessed the seasonal variation in prevalence of haemosporidian parasites (Plasmodium, Haemoproteus and Leucocytozoon) in house sparrows (Passer domesticus) sampled across 1 year at four temperate European sites spanning a latitudinal range of 17°. We showed that parasite prevalence and diversity decreased with increasing latitude, but the parasite communities differed between sites, with only one Plasmodium lineage (P_SGS1) occurring at all sites. Moreover, the nested PCR method commonly used to detect and identify haemosporidian parasites strongly underestimated co-infections of Haemoproteus and Plasmodium, significantly biasing the pattern of seasonal variation, so additional molecular methods were used. Finally, we showed that: (i) seasonal variation in prevalence of haemosporidian parasites varied between study sites and parasite lineages/species/genera, describing further cases where the double peak model is not met; (ii) the seasonal dynamics of single lineages (P_SGS1) varied between sites; and (iii) unexpectedly, seasonality was greatest at the southernmost site, a pattern that was mostly driven by lineage H_PADOM05. Limitations of the genotyping methods and consequences of pooling (parasite lineages, sites and years) in studies of haemosporidian parasites are discussed and recommendations proposed, since these actions may obscure the patterns of prevalence and limit ecological inferences.

SUBMITTER: Neto JM

PROVIDER: S-EPMC7306154 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature

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Seasonal dynamics of haemosporidian (Apicomplexa, Haemosporida) parasites in house sparrows Passer domesticus at four European sites: comparison between lineages and the importance of screening methods.

Neto Júlio Manuel JM Mellinger Samantha S Halupka Lucyna L Marzal Alfonso A Zehtindjiev Pavel P Westerdahl Helena H

International journal for parasitology 20200516 6-7

Infectious diseases often vary seasonally in a predictable manner, and seasonality may be responsible for geographical differences in prevalence. In temperate regions, vector-borne parasites such as malaria are expected to evolve lower virulence and a time-varying strategy to invest more in transmission when vectors are available. A previous model of seasonal variation of avian malaria described a double peak in prevalence of Plasmodium parasites in multiple hosts resulting from spring relapses ...[more]

PMID: 32422301

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Project description:BackgroundHosts are often simultaneously infected with several parasite species. These co-infections can lead to within-host interactions of parasites, including mutualism and competition, which may affect both virulence and transmission. Birds are frequently co-infected with different haemosporidian parasites, but very little is known about if and how these parasites interact in natural host populations and what consequences there are for the infected hosts. We therefore set out to study Plasmodium and Haemoproteus parasites in house sparrows Passer domesticus with naturally acquired infections using a protocol where the parasitemia (infection intensity) is quantified by qPCR separately for the two parasites. We analysed infection status (presence/absence of the parasite) and parasitemia of parasites in the blood of both adult and juvenile house sparrows repeatedly over the season.ResultsHaemoproteus passeris and Plasmodium relictum were the two dominating parasite species, found in 99% of the analyzed Sanger sequences. All birds were infected with both Plasmodium and Haemoproteus parasites during the study period. Seasonality explained infection status for both parasites in the adults: H. passeris was completely absent in the winter while P. relictum was present all year round. Among adults infected with H. passeris there was a positive effect of P. relictum parasitemia on H. passeris parasitemia and likewise among adults infected with P. relictum there was a positive effect of H. passeris parasitemia on P. relictum parasitemia. No such associations on parasitemia were seen in juvenile house sparrows.ConclusionsThe reciprocal positive relationships in parasitemia between P. relictum and H. passeris in adult house sparrows suggests either mutualistic interactions between these frequently occurring parasites or that there is variation in immune responses among house sparrow individuals, hence some individuals suppress the parasitemia of both parasites whereas other individuals suppress neither. Our detailed screening of haemosporidian parasites over the season shows that co-infections are very frequent in both juvenile and adult house sparrows, and since co-infections often have stronger negative effects on host fitness than the single infection, it is imperative to use screening systems with the ability to detect multiple parasites in ecological studies of host-parasite interactions.

Project description:BackgroundMaternal antibodies are believed to play an integral role in protecting immunologically immature wild-passerines from environmental antigens. This study comprehensively examines the early development of the adaptive immune system in an altricial-developing wild passerine species, the house sparrow (Passer domestics), by characterizing the half-life of maternal antibodies in nestling plasma, the onset of de novo synthesis of endogenous antibodies by nestlings, and the timing of immunological independence, where nestlings rely entirely on their own antibodies for immunologic protection.Methodology/principal findingsIn an aviary study we vaccinated females against a novel antigen that these birds would not otherwise encounter in their natural environment, and measured both antigen-specific and total antibody concentration in the plasma of females, yolks, and nestlings. We traced the transfer of maternal antibodies from females to nestlings through the yolk and measured catabolisation of maternal antigen-specific antibodies in nestlings during early development. By utilizing measurements of non-specific and specific antibody levels in nestling plasma we were able to calculate the half-life of maternal antibodies in nestling plasma and the time point at which nestling were capable of synthesizing antibodies themselves. Based on the short half-life of maternal antibodies, the rapid production of endogenous antibodies by nestlings and the relatively low transfer of maternal antibodies to nestlings, our findings suggest that altricial-developing sparrows achieve immunologic independence much earlier than precocial birds.Conclusions/significanceTo our knowledge, this is the first in depth analyses performed on the adaptive immune system of a wild-passerine species. Our results suggest that maternal antibodies may not confer the immunologic protection or immune priming previously proposed in other passerine studies. Further research needs to be conducted on other altricial passerines to determine if the results of our study are a species-specific phenomenon or if they apply to all altricial-developing birds.

Project description:Ecologists frequently use physiological tools to understand how organisms cope with their surroundings but rarely at macroecological scales. This study describes spatial variation in corticosterone (CORT) levels in feathers of invasive house sparrows (Passer domesticus) across their range in Mexico and evaluates CORT-climate relationships with a focus on temperature and precipitation. Samples were collected from 49 sites across Mexico. Feather CORT (CORTf) was measured using methanol-based extraction and radioimmunoassay. Relationships between CORTf and spatial and climate variables were examined using simple linear regressions. Ordination was used on climate data, CORTf was plotted against the resulting axes, and univariate regression trees were used to identify important predictors of CORTf. Universal kriging interpolation was used to illustrate spatial variation in CORTf across Mexico. Correlations with ordination axes showed that high CORTf was associated with low precipitation during the rainy season and low dry season temperatures. Specifically, CORTf was negatively related to May precipitation and January and July minimum temperatures, and positively related to April deuterium excess and June minimum temperatures. CORTf was higher in second-year birds compared to after-hatch years and after-second years. House sparrows had higher CORTf levels in the hot, dry, north-central region of Mexico, and CORTf was negatively related to temperature and precipitation. House sparrows molt primarily from August-September but climate conditions throughout the year were important predictors of CORTf, suggesting that conditions outside of molt can carry over to influence energetics during feather growth. These data suggest that dry conditions are challenging for house sparrows in Mexico, supporting previous work showing that precipitation is an important predictor of broad-scale CORT variation. This work highlights the utility of CORTf for evaluating the influence of physiology on current avian range limits; furthermore, these data may allow us to predict future changes in species distributions.

Dataset Information

Seasonal dynamics of haemosporidian (Apicomplexa, Haemosporida) parasites in house sparrows Passer domesticus at four European sites: comparison between lineages and the importance of screening methods.

Publications

Seasonal dynamics of haemosporidian (Apicomplexa, Haemosporida) parasites in house sparrows Passer domesticus at four European sites: comparison between lineages and the importance of screening methods.

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