First mitochondrial and nuclear DNA sequences of Lamanema chavezi (Nematoda: Molineidae): Novel findings to improve its identification in feces from South American camelids

First detection of autochthonous Lamanema chavezi infections in llamas (Lama glama) in Europe

Lamanema chavezi is one of the most pathogenic nematode species of South American camelids (SAC), with a homoxenous life cycle involving enterohepatic migration of its larvae in the host. So far, it has been found in the Americas and New Zealand. The first autochthonous L. chavezi infections in SAC in Europe are reported here. On a SAC farm in Germany, a 15-month-old male llama with a short history of diarrhoea died in September 2017, followed nine months later by a three-year-old female llama with a history of emaciation, apathy, anorexia, anaemia and tetraparesis with retained sensorium. Both animals were born and raised on the farm, which had imported three llamas directly from Chile 4-14 years earlier. At necropsy, the main lesions in both cases were numerous white-yellow to dark red foci, up to 3 mm in size, close to the Glisson's capsule and deep in the parenchyma of the liver. Histologically, the livers showed haemorrhagic tracks by and with nematode larvae and a necro-haemorrhagic to fibrinous inflammation with a predominantly lymphohistiocytic infiltration. The larvae were 30-50 μm in diameter and had external longitudinal cuticular ridges. Larvae extracted from unfixed liver tissue were 1800-2000 μm long and about 80 μm in diameter, with a terminal spine at the posterior end, which is characteristic of female L. chavezi stages. The ribosomal DNA including the almost complete 18S rRNA gene, the first internal transcribed spacer, the 5.8S RNA gene, the second internal transcribed spacer (ITS) and the partial 28S rRNA gene from isolated larvae were amplified using nematode-specific oligonucleotide primers and then sequenced. The assembled nematode sequence of 3448 bp showed an identity of 99.4% to previously published L. chavezi sequences in the BLASTN search. Low numbers of L. chavezi-like eggs were found in the faeces of seven (29%) of 24 llamas and alpacas in the herd, including some farm-born crias, tested two years after the last fatal case. The results show for the first time that L. chavezi has not only been imported into Europe from South America, but has also completed its life cycle locally, resulting in autochthonous infections of SAC. This was also suspected to be the cause of the fatal disease in two llamas.

Updated checklist of helminths found in terrestrial mammals of Argentine Patagonia

The aim of the present study was to evaluate the state of knowledge about the helminthology of wild mammals in Argentine Patagonia and its link with the conservation of parasite species and biodiversity. To this end, the information included in the previously reported checklist of the helminths found in terrestrial wild mammals of Argentine Patagonia was completed and updated. The methodology used for the search was the same as that previously used, with slight modifications. Eighty-two species of mammals currently inhabit the region, and an additional six species are considered to have become extinct before the 20th century. The reports used to complete and update the information correspond to research done since 2015 to date. Considering the number of records analysed in the previously reported checklist and those of the current update, a total of 1918 helminthological reports for current Patagonian mammals and 2141 on mammal species that inhabited Patagonia before the 20th century were accounted for. It is important to point out that 41% of the 82 species of wild mammals currently inhabiting Patagonia have not been studied helminthologically; 38% of these without helminthological records are either threatened or do not have categorization, and 79% of mammals without helminthological studies have some degree of endemism. Therefore, in order to evaluate conservation priorities, the information about the parasitic richness in Patagonian wild mammals should be substantially increased, especially in those endangered or endemic.

Current anthelmintic treatment is not always effective at controlling strongylid infections in German alpaca herds

BACKGROUND

Endoparasites are considered a major health problem of South American camelids as shown in a recent survey among German and Austrian camelid owners. Although prophylactic and therapeutic measures such as application of anthelmintics are commonly used, treatment efficacy is usually not assessed. Owners have expressed significant concerns regarding the effect of antiparasitic therapy, so this study aimed to evaluate the outcome of anthelmintic treatment in German alpaca herds with different drugs.

RESULTS

Overall, 617 samples from 538 clinically healthy alpacas > 1 year-old from 27 farms (n = 11-157 animals/herd) were examined. The most common parasites detected by flotation were Eimeria spp. (75.1%) followed by strongylids (55.0%), Nematodirus spp. (19.3%), cestodes (3.1%) and Trichuris (2.7%). After initial coproscopical examination by flotation and strongylid egg quantification by the McMaster technique, positive animals excreting at least 150 eggs per gram of faeces were included in a faecal egg count reduction test (FECRT) using fenbendazole (n = 71 samples), moxidectin (n = 71) or monepantel (n = 66). Pre-treatment larval cultures (n = 23 positive pooled farm samples) revealed Haemonchus (87% of the farms), Cooperia (43.5%), Trichostrongylus (21.7%), Ostertagia (13.0%), Nematodirus and Oesophagostomum (4.3% each). Fenbendazole treatment reduced egg excretion by 45%, moxidectin by 91% and monepantel by 96%. On the farm level, 13/18 farms that used fenbendazole, 6/6 farms that used moxidectin and 2/5 farms that used monepantel had individual FECR values < 90% (fenbendazole) or < 95% (moxidectin, monepantel). Haemonchus and Cooperia were overrepresented on the farms with reduced treatment efficacy.

CONCLUSIONS

Gastrointestinal strongylids are common in German alpacas and fenbendazole in particular was not sufficiently effective to reduce strongylid egg excretion. Although the FECRT could not unambiguously determine anthelmintic resistance in the present study, the finding that small ruminant strongylids, especially Haemonchus, are common in alpacas indicates that determination of effective anthelmintic doses, monitoring of efficacy and adapted (selective) treatment regimens must be implemented as part of sustainable deworming practices in this species in accordance with recommendations for ruminants.