Anthelmintic resistance: is a solution possible?

More than 50 years after anthelmintic resistance was first identified, its prevalence and impact on the animal production industry continues to increase across the world. The term "anthelmintic resistance" (AR) can be briefly defined as the reduction in efficacy of a certain dose of anthelmintic drugs (AH) in eliminating the presence of a parasite population that was previously susceptible. The main aim of this study is to examine anthelmintic resistance in domestic herbivores. There are numerous factors playing a role in the development of AR, but the most important is livestock management. The price of AH and the need to treat a high number of animals mean that farmers face significant costs in this regard, yet, since 1981, little progress has been made in the discovery of new molecules and the time and cost required to bring a new AH to market has increased dramatically in recent decades. Furthermore, resistance has also emerged for new AH, such as monepantel or derquantel. Consequently, ruminant parasitism cannot be controlled solely by using synthetic chemicals. A change in approach is needed, using a range of preventive measures in order to achieve a sustainable control programme. The use of nematophagous fungi or of plant extracts rich in compounds with anthelmintic properties, such as terpenes, condensed tannins, or flavonoids, represent potential alternatives. Nevertheless, although new approaches are showing promising results, there is still much to do. More research focused on the control of AR is needed.

Evaluation of the Baermann-Wetzel method for detecting lungworm larvae in wild ruminants from faecal samples.

Lungworms can exert a negative impact on wild ruminant fitness; for this reason, the diagnosis of the associated diseases is an important prevention measure. The Baerman-Wetzel technique is the most usual method for the diagnosis of bronchopulmonary nematodes and is based on the active migration and movement of their first-stage larvae. Pulmonary tissue samples are frequently used for the post-mortem diagnosis of these parasites, but this kind of sample is not always available and easy to obtain. Faecal samples represent a more accessible choice for parasite monitoring. This work aimed to evaluate the agreement between the results obtained by the Baermann-Wetzel technique when samples of lung parenchyma or faeces from wild ruminants are used. A good level of agreement as well as a similar sensitivity between the two types of sample were observed, validating the use of faecal samples as a less invasive and cost-effective alternative for the monitoring of lungworm in wild ruminant populations.

Parasite prevalence in Mycobacterium spp. infected dairy goats in the region of Murcia (south-east Spain).

Eighty-four Murciano-Granadina dairy goats slaughtered in the region of Murcia (South-East Spain) were necropsied to evaluate parasitic infections. The majority of the animals (94.0%) were parasitised and multiple infections were present. Twenty-one parasite species were found, including 18 nematode species (Muellerius capillaris, Dictyocaulus filaria, Neostrongylus linearis, Cystocaulus ocreatus, Teladorsagia circumcincta, T. occidentalis, T. trifurcata, Marshallagia marshalli, Camelostrongylus mentulatus, Trichostrongylus capricola, Nematodirus abnormalis, N. filicollis, N. spathiger, T. vitrinus, T. colubriformis, Trichuris spp., Chabertia ovina and Skrjabinema ovis); one trematode species (Dicrocoelium dendriticum); one arthropod species (Oestrus ovis); and one protozoa genus (Eimeria spp.). Additionally, 17.85% of the animals were Mycobacterium spp. positive. Therefore, comparison between parasite prevalence, intensity and abundance in tuberculosis-positive and -negative animals was performed. Statistically significant differences between the prevalence of lungworms and gastrointestinal nematodes in Mycobacterium spp. infected and free goats were found. The paper discusses this co-infection between Mycobacteriaceae and endoparasites.

Une étude a été conduite sur 84 chèvres laitières de race Murciano­Granadina abattues dans la région de Murcia (sud-est de l'Espagne) afin d'évaluer la présence d'infections parasitaires. Dans leur grande majorité (94,0 %), les chèvres étaient infestées de parasites et le nombre de pluri-infections était important. Au total, 21 espèces de parasites ont été observées, dont 18 espèces de nématodes (Muellerius capillaris, Dictyocaulus filaria, Neostrongylus linearis, Cystocaulus ocreatus, Teladorsagia circumcincta, T. occidentalis, T. trifurcata, Marshallagia marshalli, Camelostrongylus mentulatus, Trichostrongylus capricola, Nematodirus abnormalis, N. filicollis, N. spathiger, T. vitrinus, T. colubriformis, Trichuris spp., Chabertia ovina et Skrjabinema ovis), une espèce de trématode (Dicrocoelium dendriticum), une espèce d'arthropode (Oestrus ovis) et des membres d'un genre de protozoaire (Eimeria spp.). En outre, la présence de Mycobacterium spp. a été détectée chez 17,85 % des chèvres examinées. Par conséquent, une étude comparative a été réalisée pour déterminer la prévalence, l'intensité et l'abondance des parasites chez les animaux ayant donné des résultats respectivement positifs et négatifs à la détection de la tuberculose. Des différences significatives au plan statistique ont été constatées entre les chèvres infectées et indemnes de Mycobacterium spp., respectivement, pour ce qui concerne la prévalence des vers pulmonaires et des nématodes gastro-intestinaux. Les auteurs font le point sur cette co-infection par des mycobactéries et des endoparasites.

Tras ser sacrificadas, ochenta y cuatro cabras lecheras murciano­granadinas de la región de Murcia (sudeste de España) fueron sometidas a necropsia para determinar la presencia de eventuales parasitosis. La mayoría de los animales (un 94,0%) presentaban parásitos y múltiples infecciones. Se descubrieron veintiuna especies de parásito: 18 especies de nemátodo (Muellerius capillaris, Dictyocaulus filaria, Neostrongylus linearis, Cystocaulus ocreatus, Teladorsagia circumcincta, T. occidentalis, T. trifurcata, Marshallagia marshalli, Camelostrongylus mentulatus, Trichostrongylus capricola, Nematodirus abnormalis, N. filicollis, N. spathiger, T. vitrinus, T. colubriformis, Trichuris spp., Chabertia ovina y Skrjabinema ovis); una especie de tremátodo (Dicrocoelium dendriticum); una especie de artrópodo (Oestrus ovis) y un género de protozoo (Eimeria spp.). Además, el 17,85% de los ejemplares eran positivos para Mycobacterium spp. A partir de ahí se procedió a comparar la prevalencia, intensidad y abundancia de parásitos en los animales positivos para la tuberculosis con respecto a los negativos. Se observaron diferencias estadísticamente significativas entre las cabras que estaban infectadas por Mycobacterium spp. y las que no lo estaban en cuanto a la prevalencia de nemátodos pulmonares y gastrointestinales. Los autores examinan esta infección concomitante entre micobacteriáceas y endoparásitos.

First description of gastrointestinal nematodes of Barbary sheep (Ammotragus lervia): the case of Camelostrongylus mentulatus as a paradigm of phylogenic and specific relationship between the parasite and its ancient host.

The gastrointestinal helminth fauna of 24 Barbary sheep or Aoudad (Ammotragus lervia sahariensis) maintained in the Parque de Rescate de la Fauna Sahariana (PRFS, CSIC, Almeria, Spain) was analyzed. Most animals (87.5 %) were parasitized, and multiple infections were highly present. The following species were identified: Camelostrongylus mentulatus, Teladorsagia circumcincta, Marshallagia marshalli, Ostertagia ostertagi, O. leptospicularis, O. lyrata, Haemonchus contortus, Teladorsagia trifurcata, Trichostrongylus vitrinus, T. colubriformis, T. probolorus, T. capricola, Nematodirus spathiger, N. abnormalis, N. filicollis, N. helvetianus, Trichuris spp. and Skrjabinema ovis. Teladorsagia circumcincta was the most prevalent nematode in abomasum (52.6 %) followed by C. mentulatus (50 %). However, this latter nematode had the greater mean intensity and abundance. In the small intestine, T. colubriformis and T. vitrinus had the highest prevalence (36.4 %); the last one showed also the greater mean intensity and abundance. It should be emphasized the presence of Skrjabinema ovis (prevalence 39.1 %) in the large intestine, showing the greater mean abundance and intensity, although with a low values. Camelostrongylus mentulatus could be the most primitive nematode of the family trichostrongylidae recovered in this study; attending to its high prevalence, mean abundance and mean intensity, the possible specificity between this parasite and the Aoudad is discussed.

Helminths in a giraffe (Giraffa camelopardalis xgiraffa) from a zoo in Spain.

A pregnant female Cape giraffe (Giraffa camelopardalis giraffa) died from an unknown cause in the Aitana Zoo, Alicante, Spain. Neither clinical signs nor macroscopic lesions were observed at necropsy. The alimentary tract was removed and examined for parasites. A total of 2 724 nematodes were found, including Camelostrongylus mentulatus, Trichostrongylus axei, Ostertagia ostertagi, Teladorsagia circumcincta, Teladorsagia trifurcata, Marshallagia marshalli, Trichostrongylus vitrinus, Trichostrongylus colubriformis, Spiculopteragia asymmetrica and Trichuris giraffae. Only T. giraffae and C. mentulatus have been previously reported from giraffes. The other nematodes are common in mouflons, fallow and red deer, which can usually be found in the same paddock as the giraffes in Aitana Zoo. Although its occurrence is unusual in this host, C. mentulatus was the most abundant nematode in our giraffe. This parasite has been related to disease, and even death, in several wild ruminants.

Periparturient increase in faecal egg counts in a captive population of mohor gazelle (Gazella dama mhorr).

The objective of this study was to assess whether there was a periparturient rise in the faecal egg output of a population of North African gazelles (Gazella dama mhorr) kept in captivity in Almeria, southern Spain. In one experiment faeces were collected from 47 female gazelles on three days in winter, in November and December 1995 and January 1996; in a second experiment faecal samples were collected from nine pregnant gazelles at weekly intervals from July 1996 to June 1997. The mean trichostrongylid faecal egg counts were significantly higher (P < 0.05) in the periparturient gazelles than in the pregnant and non-pregnant animals only when the births took place in winter. Other factors, including the gazelle's age, its level of inbreeding, the number of previous births, and its trichostrongylid egg output at the beginning of the study did not affect whether it showed a periparturient rise. The parasites responsible for the rise were different in the two experiments.

Camelostrongylus mentulatus in domestic goats from the Iberian Peninsula.

Two male worms of Camelostrongylus mentulatus were found in one of 84 murciano-granadina goats in Murcia, south-eastern Spain. This is the first report of C. mentulatus in goats in the Iberian peninsula and the possible origin and transmission of this nematode in Spain are discussed.

Prevalence and viability of eggs of Toxocara spp. and Toxascaris leonina in public parks in eastern Spain.

To demonstrate the prevalence of Toxocara spp. and Toxascaris leonina eggs in parks in Murcia city, eastern Spain, a total 644 soil samples were examined from nine parks. More than 67% of parks and 1.24% of soil samples were contaminated and the mean egg density per sample was eggs per 100 g of soil. Over 97% of eggs identified were viable. Only one sample was positive for Toxascaris leonina. The present findings suggest that shady conditions are important for the occurrence and viability of Toxocara spp. and Toxascaris leonina eggs in soil as there were significantly more positive samples in shaded and moist areas compared with open and dry habitats.

Abomasal and small intestinal nematodes from captive gazelles in Spain.

The abomasal and small intestinal helminth fauna of three species of captive gazelles (Gazella dama mhorr, G. cuvieri and G. dorcas neglecta) kept in captivity in Almería (southeast Spain) have been studied, and the following species were identified: Nematodirus spathiger, N. filicollis, N. helvetianus, Camelostrongylus mentulatus, Trichostrongylus vitrinus, T. probolurus, T. colubriformis, Ostertagia ostertagi, O. harrisi, Teladorsagia (Ostertagia) circumcincta, and T. (Ostertagia) davtiani. Camelostrongylus mentulatus and N. spathiger were the most prevalent and abundant parasites. Ostertagia ostertagi, O. harrisi, N. helvetianus, and T. (Ostertagia) davtiani were identified for the first time in the genus Gazella. In addition, O. harrisi and Trichostrongylus probolurus are new records for Spain.