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Epidemiological traits of the malaria-like parasite Polychromophilus murinus in the Daubenton's bat Myotis daubentonii.

Witsenburg F, Schneider F, Christe P - Parasit Vectors (2014)

Bottom Line: Yet most of these studies provide only snapshots in time of the parasites discovered.During one year, we additionally measured body temperature and haematocrit values.Confusion over the identities and nomenclature of malarial-like parasites requires that molecular barcodes are coupled to accurate morphological descriptions.

View Article: PubMed Central - PubMed

Affiliation: Department of Ecology and Evolution, University of Lausanne, Biophore, CH-1015, Lausanne, Switzerland. fardo.witsenburg@unil.ch.

ABSTRACT

Background: The great diversity of bat haemosporidians is being uncovered with the help of molecular tools. Yet most of these studies provide only snapshots in time of the parasites discovered. Polychromophilus murinus, a malaria-like blood parasite, specialised on temperate-zone bats is a species that is being 'rediscovered'. This study describes the infection dynamics over time and between host sex and age classes.

Methods: For three years we followed the members of three breeding colonies of Myotis daubentonii in Western Switzerland and screened them for the prevalence and parasitemia of P. murinus using both molecular tools and traditional microscopy. In order to identify more susceptible classes of hosts, we measured, sexed and aged all individuals. During one year, we additionally measured body temperature and haematocrit values.

Results: Juvenile bats demonstrated much higher parasitemia than any other age class sampled, suggesting that first exposure to the parasite is very early in life during which infections are also at their most intense. Moreover, in subadults there was a clear negative correlation between body condition and intensity of infection, whereas a weak positive correlation was observed in adults. Neither body temperature, nor haematocrit, two proxies used for pathology, could be linked to intensities of infection.

Conclusion: If both weaker condition and younger age are associated with higher infection intensity, then the highest selection pressure exerted by P. murinus should be at the juvenile stage. Confusion over the identities and nomenclature of malarial-like parasites requires that molecular barcodes are coupled to accurate morphological descriptions.

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Related in: MedlinePlus

Results from the logistic regression. (A) Prevalence of P. murinus in local M. daubentonii through the season, separated by year. Circles and continuous line: 2010; triangles and dashed line: 2011; squares and dotted line: 2012. (B) The possibility of infection with P. murinus reduces with increased condition of the bat.
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Fig2: Results from the logistic regression. (A) Prevalence of P. murinus in local M. daubentonii through the season, separated by year. Circles and continuous line: 2010; triangles and dashed line: 2011; squares and dotted line: 2012. (B) The possibility of infection with P. murinus reduces with increased condition of the bat.

Mentions: All required data for logistic regression analyses were available for 193 bats. Infection rates increased over the season, but only in 2010 a period of peak infection appeared, around July-August (Figure 2A); other years showing either an unsteady increase (2011) or a flat trend (2012). The final model of P. murinus prevalence contained both date, year and its interaction (Table 2). All other variables were retained as well, but not their interactions or age (Table S1 in Additional file 1). The goodness-of-fit test was not significant (Hosmer-Lemeshow, X2 = 8.558, p = 0.38), but visually many variables showed no pattern at all. Many intercorrelations existed between the predictors, which can make GLM solutions very sensitive to small variations in predictors [23]. To assess the robustness of our solution, we randomly split the data in two and three subsets, each subset containing respectively 50% or 33% of all observations, and used these to retest our model. Upon retesting, many variables disappeared from the model. Only date appeared as a reliable predictor and, with the exception of one model, body condition as well (Figure 2B; Table S3 in Additional file 1).Figure 2


Epidemiological traits of the malaria-like parasite Polychromophilus murinus in the Daubenton's bat Myotis daubentonii.

Witsenburg F, Schneider F, Christe P - Parasit Vectors (2014)

Results from the logistic regression. (A) Prevalence of P. murinus in local M. daubentonii through the season, separated by year. Circles and continuous line: 2010; triangles and dashed line: 2011; squares and dotted line: 2012. (B) The possibility of infection with P. murinus reduces with increased condition of the bat.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4269171&req=5

Fig2: Results from the logistic regression. (A) Prevalence of P. murinus in local M. daubentonii through the season, separated by year. Circles and continuous line: 2010; triangles and dashed line: 2011; squares and dotted line: 2012. (B) The possibility of infection with P. murinus reduces with increased condition of the bat.
Mentions: All required data for logistic regression analyses were available for 193 bats. Infection rates increased over the season, but only in 2010 a period of peak infection appeared, around July-August (Figure 2A); other years showing either an unsteady increase (2011) or a flat trend (2012). The final model of P. murinus prevalence contained both date, year and its interaction (Table 2). All other variables were retained as well, but not their interactions or age (Table S1 in Additional file 1). The goodness-of-fit test was not significant (Hosmer-Lemeshow, X2 = 8.558, p = 0.38), but visually many variables showed no pattern at all. Many intercorrelations existed between the predictors, which can make GLM solutions very sensitive to small variations in predictors [23]. To assess the robustness of our solution, we randomly split the data in two and three subsets, each subset containing respectively 50% or 33% of all observations, and used these to retest our model. Upon retesting, many variables disappeared from the model. Only date appeared as a reliable predictor and, with the exception of one model, body condition as well (Figure 2B; Table S3 in Additional file 1).Figure 2

Bottom Line: Yet most of these studies provide only snapshots in time of the parasites discovered.During one year, we additionally measured body temperature and haematocrit values.Confusion over the identities and nomenclature of malarial-like parasites requires that molecular barcodes are coupled to accurate morphological descriptions.

View Article: PubMed Central - PubMed

Affiliation: Department of Ecology and Evolution, University of Lausanne, Biophore, CH-1015, Lausanne, Switzerland. fardo.witsenburg@unil.ch.

ABSTRACT

Background: The great diversity of bat haemosporidians is being uncovered with the help of molecular tools. Yet most of these studies provide only snapshots in time of the parasites discovered. Polychromophilus murinus, a malaria-like blood parasite, specialised on temperate-zone bats is a species that is being 'rediscovered'. This study describes the infection dynamics over time and between host sex and age classes.

Methods: For three years we followed the members of three breeding colonies of Myotis daubentonii in Western Switzerland and screened them for the prevalence and parasitemia of P. murinus using both molecular tools and traditional microscopy. In order to identify more susceptible classes of hosts, we measured, sexed and aged all individuals. During one year, we additionally measured body temperature and haematocrit values.

Results: Juvenile bats demonstrated much higher parasitemia than any other age class sampled, suggesting that first exposure to the parasite is very early in life during which infections are also at their most intense. Moreover, in subadults there was a clear negative correlation between body condition and intensity of infection, whereas a weak positive correlation was observed in adults. Neither body temperature, nor haematocrit, two proxies used for pathology, could be linked to intensities of infection.

Conclusion: If both weaker condition and younger age are associated with higher infection intensity, then the highest selection pressure exerted by P. murinus should be at the juvenile stage. Confusion over the identities and nomenclature of malarial-like parasites requires that molecular barcodes are coupled to accurate morphological descriptions.

Show MeSH
Related in: MedlinePlus