Helminths of the Wild Boar (Sus scrofa) from Units of Conservation Management and Sustainable Use of Wildlife Installed in the Eastern Economic Region of Mexico

Abstract

Wild boars (Sus scrofa) were introduced in Mexico for sport hunting and meat trading for human consumption, but the available data regarding their role in pathogen transmission are limited. This research and field work aimed to identify the helminths of the wild boar produced in three units of conservation management and sustainable use of wildlife placed in the eastern economic region of Mexico. Samples of feces and serum were collected from 90 animals that came from three different ranches. Stool examination and antibody determination to Fasciola hepatica, Taenia crassciceps, Ascaris suum, Toxocara canis (ELISA), and Trichinella spiralis (Western blot) were performed. In addition, 30 diaphragm samples from one ranch were obtained for artificial digestion. Eggs of Strongyloides sp. (72.2%), Metastrongylus sp. (57.7%), Oesophagostomum sp. (53.3%), and Trichuris sp. (37.7%) were found in addition to oocysts of Eimeria sp. (75.6%). Antibodies to Fasciola (8.9%), Taenia (4.4%), Ascaris (32.2%), Toxocara (20%), and Trichinella (5.5%) were found. The eggs of Strongyloides and Oesophagostomum were associated to female hosts. One nematode larva was found by artificial digestion. This is the first report to identify helminths from wild boars in Mexico. In addition, this study identifies the potential risk of the wild boar as a transmission channel of parasites that can have an impact on public health.

Keywords: Mexico; antibody; feral pig; helminth; parasite; wild boar.

Figure 1

Parasites found during the analysis of biological samples from wild boars from units of conservation management and sustainable use of wildlife installed at the eastern economic region of Mexico. Results of stool exam showed cysts of Eimeria sp. ((A), the bottom right line measures 5 um) and eggs of Strongyloides sp., (B), Metastrongylus sp. (C), Oesophagostomum sp. (D) and Trichuris sp. (E); the bottom right line measures 10 μm. (F) shows the larvae of the nematode recovered by enzymatic digestion and (G,H) show a Trichinella muscle larvae obtained from the enzymatic digestion of an experimentally infected mouse; lines are 100 μm.

Figure 2

Reactivity of wild boar serum samples against different antigenic extracts of helminths. The absorbance values obtained by ELISA are shown as a function of the antigens of Ascaris suum, Toxocara canis, Fasciola hepatica, and Taenia crassiceps. The dotted lines represent the cutoff value. The negative control (▼) is a pig serum obtained from a technical farm. The sera that were used as positive controls (▲) in the Ascaris (pig), Toxocara (dog), and Fasciola (cow) tests were obtained from natural infections, while in the case of T. crassiceps, the serum of an experimentally infected mouse was used.

Figure 3

Western blot reactivity of the wild boar serum samples against the excretion and secretion antigens of Trichinella spiralis. The figure shows the reactivity of each serum sample obtained from the wild boars. The strips are grouped by location (Hidalgo, Tlaxcala, Puebla). The positive control serum (P) corresponds to an experimentally infected rat serum, while the negative control serum (N) was from healthy rat. The molecular weight marker is shown to the left of the photo. The positive samples corresponded to three male wild boars (M) and two females (F).