Gastrointestinal helminthosis in fallow deer (Dama dama) and their response to treatment with anthelmintics

The first finding of Dictyocaulus cervi and Dictyocaulus skrjabini (Nematoda) in feral fallow deer (Dama dama) in Australia

Feral deer are widespread throughout Australia with the capacity to impact livestock production via transmission of parasites. Samples of Dama dama (fallow deer), Rusa unicolor (sambar deer), Cervus elaphus (red deer) and an unidentified deer were sourced from various locations in south-eastern Australia for examination for parasites. Adult nematodes were collected from the lungs of all deer species across four separate geographical locations. The nematodes were identified as species of Dictyocaulus through both morphological and molecular means. Species identification based on morphological features was difficult, with many measurements from described species overlapping. Molecular analyses targeting three markers, namely 18S rRNA, ITS2, and cox1 revealed the presence of two distinct species: Dictyocaulus cervi and Dictyocaulus skrjabini. These are the first genetically confirmed reports of species of Dictyocaulus in feral deer in Australia, and although cross-transmission of species of Dictyocaulus with livestock has not yet been reported, it cannot be completely discounted without further research.

Benzimidazole resistance in Haemonchus contortus recovered from farmed red deer

Thirty Haemonchus contortus male worms were collected from farmed red deer yearlings in order to determine whether routine administration of albendazole for a long-term period (17 years) could select anthelmintic resistance. PCR-RFLP method based on single-nucleotide polymorphism of codon 200 in isotype 1 ß-tubulin gene (Phe200Tyr) was applied. The results showed a significant frequency of either the resistant allele (85 %) or the homozygous resistant genotype (70 %). By chi-square test, Hardy-Weinberg equilibrium of the population was accepted (p = 0.334, power of test 0.01). True prevalence of the resistant genotype (RR) was estimated to be 46.5-87.2 % (confidence interval 95 %) calculated by Sterne's exact method. These results confirmed that long-term use of benzimidazoles could change the relative allele frequency of genes associated with drug resistance and may cause a large-scale spread of the resistant allele. To our knowledge, this study supported benzimidazole resistance in Haemonchus contortus in red deer for the first time.

Diagnosis, Treatment and Management of Haemonchus contortus in Small Ruminants

Haemonchus contortus is a highly pathogenic, blood-feeding nematode of small ruminants, and a significant cause of mortalities worldwide. Haemonchosis is a particularly significant threat in tropical, subtropical and warm temperate regions, where warm and moist conditions favour the free-living stages, but periodic outbreaks occur more widely during periods of transient environmental favourability. The clinical diagnosis of haemonchosis is based mostly on the detection of anaemia in association with a characteristic epidemiological picture, and confirmed at postmortem by the finding of large numbers of H. contortus in the abomasum. The detection of impending haemonchosis relies chiefly on periodic monitoring for anaemia, including through the 'FAMACHA' conjunctival-colour index, or through faecal worm egg counts and other laboratory procedures. A range of anthelmintics for use against H. contortus is available, but in most endemic situations anthelmintic resistance significantly limits the available treatment options. Effective preventative programmes vary depending on environments and enterprise types, and according to the scale of the haemonchosis risk and the local epidemiology of infections, but should aim to prevent disease outbreaks while maintaining anthelmintic efficacy. Appropriate strategies include animal management programmes to avoid excessive H. contortus challenge, genetic and nutritional approaches to enhance resistance and resilience to infection, and the monitoring of H. contortus infection on an individual animal or flock basis. Specific strategies to manage anthelmintic resistance centre on the appropriate use of effective anthelmintics, and refugia-based treatment schedules. Alternative approaches, such as biological control, may also prove useful, and vaccination against H. contortus appears to have significant potential in control programmes.

The efficacy of ivermectin and levamisole against natural Nematodirus spathiger infection in the Arabian sand gazelle (Gazella subgutturosa marica) and the Arabian mountain gazelle (Gazella gazella) in Saudi Arabia

The efficacy of two broad spectrum anthelmintics (Ivermectin and Levamisole) against the nematode Nematodirus spathiger in the reem (Arabian sand gazelle) and idmi (Arabian mountain gazelle) at King Khalid Wildlife Research Centre (KKWRC) was determined. Gazelles of both species naturally infected with N. spathiger were each divided into 3 groups. One group was treated with Ivermectin, the other group with Levamisole and the last group was left as untreated control. Faecal egg counts were employed to determine the efficacy of the two drugs against N. spathiger infection in both gazelle species. Reduction in arithmetic mean faecal egg counts achieved by Ivermectin and Levamisole in the reem gazelles was 94% and 89.3%, respectively. The reduction in the idmi gazelles was 97.2% and 96.4%, respectively. Hence, both anthelmintics appeared to be more effective in the idmi gazelles than in the reem gazelles, however, there was no significant difference in the faecal egg reduction tests in both animal species.

A 12-month survey of gastrointestinal helminth infections of cervids kept in two zoos in Belgium

Infections with helminths are a major health issue in captive and wild deer. In this study, fecal egg count patterns and clinical signs associated with gastrointestinal nematodes were assessed for 12 mo in nine cervid herds kept under different husbandry conditions at two sites. At site 1, an urban zoo, fecal egg counts remained low and no clinical signs of parasitic gastroenteritis were seen in the herds of fallow deer (Dama dama), Dybowski's deer (Cervus nippon dybowski), pudu (Pudu pudu), and reindeer (Rangifer tarandus tarandus). Helminth infection at this site may have been successfully prevented by daily dung removal of the small sandy-soil enclosures, and applying routine anthelmintic treatment was not justified. At site 2, a wild animal park, involved species were red deer (Cervus elaphus hippelaphus), Nelson's elk (Cervus elaphus nelsoni), Père David's deer (Elaphurus davidianus), European elk (Alces alces alces), and reindeer (Rangifer tarandus tarandus). Nematode eggs were frequently encountered in herds of red deer, Nelson's elk, and European elk, which were kept on larger, grassy enclosures that were irregularly cleaned. The trimodal pattern of fecal egg counts in herds from the wild animal park, consisting of a small spring rise in June, a peak in October, and a small rise in February, indicates that infective larvae on pastures are the main source of infection. In addition, routine anthelmintic treatment with fenbendazole in April and July limited egg shedding, but reinfection rapidly occurred. In two European elk and one reindeer, increasing fecal egg counts were associated with loss of fecal consistency and reduced appetite. Three genera and three species of nematodes were recovered at necropsy of one red deer and three Nelson's elk: Spiculopteragia spiculoptera, Trichostrongylus spp., Nematodirus filicollis, Capillaria spp., Oesophagostomum radiatum, and Trichuris spp., with total worm counts between 950 and 8,700.