An identification key for the five most common species of Metastrongylus

Abstract

Species of the Metastrongylus genus, the lung nematodes of pigs that require an intermediate host (earthworm) to complete their cycle, pose a potential risk to both livestock and humans. This parasite which can result in lung pathology and mixed infections with other pathogens (e.g. viruses) can be fatal to pigs. Although this genus is distributed worldwide, there are no classification keys for identifying this common parasite species. In this work, we take advantage of parasitological surveys of wild boar (Sus scrofa) in northern and central Spain and southern Poland to develop a morphological identification key for the five most common Metastrongylus species (Metastrongylus apri, Metastrongylus pudendotectus, Metastrongylus salmi, Metastrongylus confusus and Metastrongylus asymetricus). In addition, we provide the first record of M. confusus in Spain, probably unidentified until now due to the lack of appropriate identification keys. We hope that this user-friendly identification key will enable parasitologists and veterinary practitioners to avoid further misclassifications of Metastrongylus species.

The physiological cost of male-biased parasitism in a nearly monomorphic mammal

“…Adult nematodes were recovered from the lungs, preserved in 70% ethanol and later mounted in lactophenol for identification [17]. Lung larvae were obtained using the Baermann method on 30 g of lung parenchyma.…”

Human Pulmonary Infection by the Zoonotic Metastrongylus salmi Nematode. The First Reported Case in the Americas

“…[2][3][4]6,14 Other animals such as sheep, cattle, deer, and other ruminants are less commonly infected. 1 In Ecuador, infection in swine has been reported from the three geographical regions.…”

“…1 The Metastrongylus genus, comprising eight different species: Metastrongylus apri or M. elongatus, Metastrongylus salmi, Metastrongylus pudendotectus, Metastrongylus confusus, Metastrongylus asymmetricus, Metastrongylus madagascariensis, Metastrongylus pulmonalis, and Metastrongylus tschiauricus, are distributed worldwide. 6,7 They usually present as mixed infections as reported in Florida, where feral swine were infected with M. apri, M. salmi, and M. pudendotectus with a prevalence of 94%, 76%, and 64%, respectively. 3 In Ecuador, M. salmi has been reported infecting Tayassu pecari from the Amazon region.…”

“…Several female and male worm specimens were clarified in lactophenol solution and identified as to the genus and species by utilizing documented morphological characteristics. 2,6,7 With the females, measuring from 15 to 30 mm, the caudal end was a finger-like tail, with the vulva situated just anterior to the anus, and several eggs in their uteri. For the males, measuring from 10 to 18 mm, the bursa copulatrix was relatively small with doubled dorsal rays; the spicule measured 1,940 μm long and the gubernaculum was 50 μm long ( Figure 2).…”

Cystic echinococcosis and other helminth infections of wild boar in northeastern and northwestern regions of Tunisia

“…After discarding large pieces of tissue, lungworms were collected in the sediment and mounted in chloral lactophenol solution (44%). The shape and length of spicules as well as the size and ray arrangement of the copulatory bursa were used to identify metastrongylid species as previously described (Skrjabin et al ., 1952; Gassó et al ., 2014).…”