9 research outputs found
Detection, prevalence, and transmission of avian hematozoa in waterfowl at the Arctic/sub-Arctic interface: co-infections, viral interactions, and sources of variation
Background
The epidemiology of avian hematozoa at high latitudes is still not well understood, particularly in sub-Arctic and Arctic habitats, where information is limited regarding seasonality and range of transmission, co-infection dynamics with parasitic and viral agents, and possible fitness consequences of infection. Such information is important as climate warming may lead to northward expansion of hematozoa with unknown consequences to northern-breeding avian taxa, particularly populations that may be previously unexposed to blood parasites.
Methods
We used molecular methods to screen blood samples and cloacal/oropharyngeal swabs collected from 1347 ducks of five species during May-August 2010, in interior Alaska, for the presence of hematozoa, Influenza A Virus (IAV), and IAV antibodies. Using models to account for imperfect detection of parasites, we estimated seasonal variation in prevalence of three parasite genera (Haemoproteus, Plasmodium, Leucocytozoon) and investigated how co-infection with parasites and viruses were related to the probability of infection.
Results
We detected parasites from each hematozoan genus in adult and juvenile ducks of all species sampled. Seasonal patterns in detection and prevalence varied by parasite genus and species, age, and sex of duck hosts. The probabilities of infection for Haemoproteus and Leucocytozoon parasites were strongly positively correlated, but hematozoa infection was not correlated with IAV infection or serostatus. The probability of Haemoproteus infection was negatively related to body condition in juvenile ducks; relationships between Leucocytozoon infection and body condition varied among host species.
Conclusions
We present prevalence estimates for Haemoproteus, Leucocytozoon, and Plasmodium infections in waterfowl at the interface of the sub-Arctic and Arctic and provide evidence for local transmission of all three parasite genera. Variation in prevalence and molecular detection of hematozoa parasites in wild ducks is influenced by seasonal timing and a number of host traits. A positive correlation in co-infection of Leucocytozoon and Haemoproteus suggests that infection probability by parasites in one or both genera is enhanced by infection with the other, or that encounter rates of hosts and genus-specific vectors are correlated. Using size-adjusted mass as an index of host condition, we did not find evidence for strong deleterious consequences of hematozoa infection in wild ducks.Geological Survey (U.S.) (Wildlife Program of the Ecosystem Mission Area)U.S. Fish and Wildlife ServiceDelta Waterfowl FoundationInstitute for Wetland and Waterfowl ResearchIcahn School of Medicine at Mount Sinai (Center for Research on Influenza Pathogenesis)Center of Excellence for Influenza Research and Surveillance (contracts HHSN272201400008C and HHSN266200700010C
Intensity of haemosporidian infection of parids positively correlates with proximity to water bodies, but negatively with host survival
In birds, haemosporidian parasites have been found to have direct pathogenic effects on the host with important consequences for their fitness. However, less is known about distribution patterns of parasite vectors, which may significantly affect parasite prevalence, infection intensity and, thus, pathogenicity in hosts. Here, we tested for relationships between infection intensity, survival, predation and distance from water bodies of mixed-species tit flocks. We found that the prevalence of Haemoproteus and Plasmodium infections decreased with increasing distance from forest lakes and bogs outside the bird breeding season. Haemoproteus and Plasmodium parasites were found to be associated with a low survival rate of willow tits (Poecile montanus) in the vicinity of water bodies, while crested tits (Lophophanes cristatus) were affected only by Haemoproteus. Crested tits, a dominant species of parid social groups, had a lower parasite prevalence and they survived better than the subordinate willow tit. This can be explained by the crested tits foraging higher in the pine canopy as parasite vectors supposedly cannot reach hosts in the upper canopy as equally as in lower parts of the canopy. We show that individuals staying in flocks further from the forest water bodies and spending more time foraging in the upper parts of the canopy have higher chances of survival into the next breeding season. This suggests that different forest and canopy areas may differ in terms of parasite risk and associated mortality. Finally, we found that the infection status of parids increases the probability of predation by the pygmy owl (Glaucidium passerinum). We conclude that distance from water bodies and foraging location in the forest canopy may affect the intensity of parasite infection with fitness consequences in wintering parids
Geographic and host distribution of haemosporidian parasite lineages from birds of the family Turdidae
Background: Haemosporidians (Apicomplexa, Protista) are obligate heteroxenous parasites of vertebrates and blood-sucking dipteran insects. Avian haemosporidians comprise more than 250 species traditionally classified into four genera, Plasmodium, Haemoproteus, Leucocytozoon, and Fallisia. However, analyses of the mitochondrial CytB gene revealed a vast variety of lineages not yet linked to morphospecies. This study aimed to analyse and discuss the data of haemosporidian lineages isolated from birds of the family Turdidae, to visualise host and geographic distribution using DNA haplotype networks and to suggest directions for taxonomy research on parasite species. Methods: Haemosporidian CytB sequence data from 350 thrushes were analysed for the present study and complemented with CytB data of avian haemosporidians gathered from Genbank and MalAvi database. Maximum Likelihood trees were calculated to identify clades featuring lineages isolated from Turdidae species. For each clade, DNA haplotype networks were calculated and provided with information on host and geographic distribution. Results: In species of the Turdidae, this study identified 82 Plasmodium, 37 Haemoproteus, and 119 Leucocytozoon lineages, 68, 28, and 112 of which are mainly found in this host group. Most of these lineages cluster in the clades, which are shown as DNA haplotype networks. The lineages of the Leucocytozoon clades were almost exclusively isolated from thrushes and usually were restricted to one host genus, whereas the Plasmodium and Haemoproteus networks featured multiple lineages also recovered from other passeriform and non-passeriform birds. Conclusion: This study represents the first attempt to summarise information on the haemosporidian parasite lineages of a whole bird family. The analyses allowed the identification of numerous groups of related lineages, which have not been linked to morphologically defined species yet, and they revealed several cases in which CytB lineages were probably assigned to the wrong morphospecies. These taxonomic issues are addressed by comparing distributional patterns of the CytB lineages with data from the original species descriptions and further literature. The authors also discuss the availability of sequence data and emphasise that MalAvi database should be considered an extremely valuable addition to GenBank, but not a replacement
Effects of ecological gradients on tropical avian haemoparasites
Diego Santiago-Alarcón y Alfonso Marzal (eds.); Primera Edición; 910 páginasThis chapter provides a brief overview of how natural gradients (e.g., latitude, altitude, and landscape gradients) affect host–parasite interactions involving blood parasites in wildlife and how biotic and abiotic factors act as disruptors. These gradients have a direct impact on prevalence, parasitemia, and the observed relationships between parasites and hosts. In the tropical zone, altitudinal gradients imitate the behavior of the latitudinal gradient, since low temperatures are common at both higher altitudes and higher latitudes. Temperature is one of the determining factors of the diversity of vectors, hosts, and vegetation that affect parasite transmission cycles. Furthermore, within landscapes, there may be many types of elements producing gradients. For instance, increasing distance from water sources, anthropogenic degradation, and even sequential stages of succession and interspersion of vegetation communities would affect host–parasite–vector interactions. However, such effects do not always operate in the same direction because responses are context sensitive. We also discuss the importance of an integrative diagnosis, using microscopic and molecular approaches, which allow better approximations and analyses at the parasite species level, thus producing stronger conclusions. The same detail is recommended for studies on the hematophagous fauna of potential vectors. The life cycle of different parasite species has its own set of characteristics, and it corresponds to the researchers to unravel the puzzle and to avoid unwarranted generalizations.The work of SM is supported by project PGC2018-097426-B-C21 from the Spanish Ministry of Science, Innovation, and Universities. The work of LC-V was funded by the National Council for Science and Technology of Mexico (CONACYT; grants SEP-CB-2012-1-183377, and PDCPN-2015-1-1628).Peer reviewe