A Comparison of the Parasites of Wild and Domestic Pigs in New Zealand

Abstract

Twenty-two wild pigs and carcases and viscera of numerous domestic pigs were examined for the presence end intensity of infestation of parasites. Forty wild pig faecal samples were examined for eggs and cysts of parasites. Fourteen species of parasites and an anaplasma-like body were encountered during this survey. The following parasites are recorded from both groups of pigs. The figures given without brackets refer to the wild group, while those with brackets refer to the domestic group: Balantidium coli 61.9% (40%), Eimeria debliecki 4.7% (68%), Anaplasma 6.6% (70%), Cysticercus tenuicollis 4.7% (50.8%), Hypostrongylus rubidus 28.5% (48%), Ascaris suum 42.8% (1.2%), Metastrongylus elongatus 66.6% (26%), Choerostrongylus pudendotectus 38% (16%), Haematopinus suis 68.1% (49.3%), and Sarcoptes scabiei var. suis 4.5% (36%). Oesophagostomum dentatum infested 14.2%, and Demodex phylloides was present among the wild group. Echinococcus granulosus (10%), Fasciola hepatica (Present), Trichuris suis (20%) and Globocephalus urosubulatus (4%) infested only the domestic group. The environmental habitats of both groups of pigs are correlated with the incidence and intensity of infestations of the parasites, and, where possible, with the life history of the parasites and the viability of the eggs. Illustrations of parasites present, and of series of developing eggs of A. suum and H. rubidus, together with the developing larvae of M. elongatus and C. pudendotectus, appear in the plates. Illustrations of anaplasma-like bodies are presented in the text. Measurements are given for the identification of parasites, and egg-counts from some nematodes recorded. Sex ratios of nematodes are given. Females were usually present in greater numbers that males. Adult specimens of M. elongatus, C. pudendotectus and A. suum were cultured in vitro in several media, and the egg-production of 5 worms of A. suum was observed. Specimens of A. suum survived longest in Baldwin and Moyle's culture fluid maintained at body temperature. Specimens of M. elongatus and C. pudendotectus survived longest in Ringer's solution held at room temperatures, and least in cultures maintained at body temperatures. Graphs have been prepared illustrating these survival periods. Results obtained by other workers on the incidence of similar parasites in New Zealand and other countries, are compared with those obtained during this survey. The incidence and intensity of parasitic infestations of pigs in New Zealand is correlated with the habits of the wild and domestic animals in their respective habitats, the varying environmental factors, and the viability of resting and infective stages of the parasites.