Parasitic infection and health status in the field mouse Akodon azarae

PALAVECINO, C; FIAMA E. PEÑA; MARÍA C. FANTOZZI; MORENO PABLO

Conferencia; Ecology and Evolution of Infectious Diseases Conference; 2021

Host?shealthandfitnessdependonitsabilitytolimitparasiticload,ortorestrictthedamagecausedbyparasites.Wildpopulationsareexposedtoawidevarietyofstressors(includingparasites)thatelicitphysiologicalresponsesneededtomaintaingoodhealth.Weevaluatedtherelationshipbetweenparasiteinfection,intrinsichostcharacteristics,andcellularimmuneresponseinwildpopulationsofthefieldrodent,Akodonazarae.Atotalof145individualswerecapturedin22regulartrappingsessions(June2014‐September2016)in8fixedgridsplacedincentralArgentina,insavannasofthetemperateNeotropicalregion.Weusedmultiplemodelinference(linearmixedmodels)toevaluatepossiblepredictorsofbloodcellcounts.Leukocyte,lymphocyte,neutrophilandeosinophilcountswereconsideredasresponsevariables.Independentvariableswereindividualfactorssuchassex,age,andbodycondition;ecologicalattributes(parasiterichness);andparasitologicaldescriptors(parasiteintensity).Seasonandyearofcapturewereincludedtocontrolforpossibleconfounding.Micewithincreasedendoparasiticrichnessshowedhigherlevelsofeosinophils,withatendencytobeoflowermagnitudeinmales.Thismightindicateacoursetoresistinfectionasvariabilityofinternalparasitesincreases.Moreover,thelowerincreaseinmalesisconsistentwithandrogensimmunosuppressiveeffects(immunocompetencehandicaphypothesis).However,lymphocytelevelswerehigherinmales,butwithoutanassociationwithparasiticvariables.Onpolygynicmatingsystemitisexpectedthatthebenefitsofincreasedmatingsuccessinmalesbalancethecostsofreducedlifespanduetodisease.Thismightindicatethatsexbiasinimmuneresponsemightdependonthecomponentoftheimmunesystembeingstudied,thematingsystemandtheeffectofsexhormones.Abetterunderstandingofinfectiondynamicsinwildrodentpopulationsiscrucialtogeneratepreventivemeasuresforpublichealth,morethanever,giventheincreasingnumberofzoonoticdiseases