Age distribution and seasonal dynamics of abomasal helminths in wild red deer from central Spain.

A study on age distribution and seasonal dynamics of abomasal helminths in wild red deer was conducted in central Spain, by monthly samplings of fawns (<1 yr), subadult (1-2 yr), and adult (>2 yr) animals. Both intensity and prevalence of abomasal parasitism were higher in older animals, particularly in males. A bimodal pattern for intensity of infection by gastrointestinal parasites was observed. Maximum values attained in winter and summer may be related to variation in climate and the shifting availability of forage resources. The pattern was largely due to the contribution of Spiculopteragia asymmetrica/Spiculopteragia quadrispiculata, whereas the other species found (Ostertagia leptospicularis/Ostertagia kolchida and Ostertagia drozdzi/Ostertagia ryjikovi) occurred with lower prevalence and intensity of infection. Among these ostertagiines, the ratio for major and minor morphotypes of males of respective species and the relative abundance of males and females were stable through the annual cycle.