Strongyloides stercoralis infection in dogs in Austria: two case reports

A severe case of hyperinfection by Strongyloides stercoralis in a pet dog from Romania

Strongyloides stercoralis is a zoonotic soil-transmitted nematode affecting mainly humans and dogs but identified also in non-human primates, cats and wild carnivores. It has a cosmopolitan distribution being endemic in tropical and subtropical areas. In Romania, the infection was reported on several occasions in dogs with low prevalence (3.5% -3.8%), assessed by coproscopy and it was confirmed in human patients with no travel history. A 2-year-old male Boston Terrier dog presented to a private clinic due to severe digestive problems, in July 2022. The animal had a long history of health problems. The dog was in a very bad clinical condition with severe abdominal pain, bloody diarrhea, and weight loss. Coproparasitological examinations using the saline flotation method and the modified Baermann's technique were done, both being negative. In addition, an intestinal biopsy was performed during the second endoscopy. Nematodes were collected and identified morphologically and molecularly confirmed. Histology revealed severe inflammation of the duodenal mucosa with areas of edema, necrosis, and hemorrhage, and in the intestinal glands, there were numerous nematodes suggesting a parasitic infection by Strongyloides spp. PCR followed by sequencing confirmed the infection with S. stercoralis. The dog was treated with a combination of oral fenbendazole and milbemycin oxime for 5 months. No relapse was observed 3 months after negativity was attained. This case describes a severe clinical infection by Strongyloides stercoralis in a domestic dog from Romania and the recovery after long-term treatment.

High-throughput sequencing of Strongyloides stercoralis - a fatal disseminated infection in a dog

The rhabditid nematode Strongyloides stercoralis is known worldwide as the causative agent of strongyloidiasis in humans. In addition to public health concerns, S. stercoralis also infects dogs, which represent a possible reservoir for potentially zoonotic transmissions. We describe the first confirmed case of fatal disseminated infection in a dog in the Czech Republic. The microscopic and histological results were supported by a complex genotyping approach. Using high-throughput sequencing of the hypervariable region (HVR-IV) of 18S rDNA and Sanger sequencing of the partial cytochrome c oxidase subunit 1 gene (cox1), the potentially zoonotic haplotype/lineage A of S. stercoralis was confirmed, while the solely canine haplotype/lineage B was not found. The development of the disease is mainly associated with immunodeficiency, and in this case, it was triggered by inappropriate treatment, in particular the use of corticosteroids.

Identification and treatment of Strongyloides stercoralis infection in a Boston Terrier dog from south-eastern Australia

Strongyloides stercoralis, the causative agent of strongyloidiasis, is a potentially zoonotic intestinal nematode endemic to northern Australia. Strongyloidiasis is typically observed in immunocompromised hosts and is characterised by gastrointestinal signs, respiratory symptoms and a failure to thrive. In immunocompromised hosts, hyperinfection syndrome and disseminated infections can prove life-threatening. A 24-month-old Boston Terrier dog was referred for investigation of chronic small and large intestinal watery hematochezic diarrhoea, emaciation and hematemesis. Small intestinal histology identified a nematode despite consecutive negative faecal flotations. A real-time polymerase chain reaction and Baermann test subsequently confirmed infection with S. stercoralis. The dog had received an oral parasiticide comprising milbemycin oxime and afoxolaner every month for the 11 months prior to this diagnosis. Despite fenbendazole being reported as successful in the treatment of canine strongyloidiasis, a course of fenbendazole failed to clear the infection. Eradication of S. stercoralis infection was confirmed after the administration of off-label ivermectin fortnightly for 12 doses. Attention should be paid to this nematode as the failure of routine copromicroscopic methods to diagnose S. stercoralis infections can result in misdiagnosis, mistreatment and progression of the disease. Off-label ivermectin may be an alternative to fenbendazole for the treatment of Strongyloides spp. infection in dogs.

First identification of Strongyloides stercoralis infection in a pet dog in Argentina, using integrated diagnostic approaches

BACKGROUND

Strongyloides stercoralis is a soil-transmitted intestinal nematode with a complex life cycle that primarily affects humans, non-human primates, dogs, and occasionally cats. This study presents, to the best of our knowledge, the first case of S. stercoralis infection and its genotyping in a domestic dog from Argentina.

METHODS

The patient was a female wired-haired Teckel dog exhibiting recurrent coughing. Coproparasitological analysis using the Baermann technique revealed the presence of rhabditiform larvae morphologically compatible with S. stercoralis. To confirm this finding, molecular diagnosis (18S ribosomal RNA) and analysis of the cox1 gene were performed.

RESULTS

We identified a haplotype (HP20) that has previously only been related to S. stercoralis infection in dogs, but was found in the present study to be highly related to the haplotype (HP16) of a zoonotic variant and divergent from those previously described from human patients in Argentina. Furthermore, unlike in human cases following treatment with ivermectin, the dog was negative after moxidectin treatment according to polymerase chain reaction of the sampled faeces.

CONCLUSIONS

This case report shows the importance of further investigation into potential transmission events and prevalences of S. stercoralis in dogs and humans in South America. The results reported here should also encourage future work that examines different scenarios of infection with S. stercoralis in dogs and humans with the aim of integrating clinical management, diagnosis, treatment and follow-up strategies in the quest for new approaches for the treatment of this disease in animals and humans. The findings support the adoption of a One Health approach, which recognizes the interconnectedness between animal and human health, in addressing parasitic infections such as strongyloidiasis.

The prevalence of potentially zoonotic intestinal parasites in dogs and cats in Moscow, Russia

This study was aimed to determine the prevalence of Toxocara canis/cati, Strongyloides stercoralis, Giardia spp., and Cryptosporidium spp., which occur and are potentially zoonotic to humans in domestic dogs and cats in Moscow (Russia). The fecal flotation method and larvae detection by microscopy of a direct feces smear were performed to detect Toxocara, Giardia spp., and Cryptosporidium spp. The total parasitic prevalence in dogs was as follows: Giardia spp.: 10.2 % (226/2208), Cryptosporidium spp.: 2.7 % (60/2208), T. canis: 2 % (45/2208), S. stercoralis larvae: 1.1 % (25/2208). The younger animals under were infected more than those over 12 months of age (p<0.001). The preva lence rates were along these lines: Giardia spp. (18.2 %), Cryptosporidium spp. (5.7 %), T.canis (3 %), S. stercoralis larvae (2.3 %). The overall prevalence in cats was as follows: Giardia spp. - 5.2 % (71/1350), Cryptosporidium spp. - 4.8 % (65/1350), T. cati - 4.1 % (56/1350). Similarly to dogs, the infection rates were higher in cats under 12 months of age Giardia spp. (8.2 %), Cryptosporidium spp. (8.6 %), T. cati (7.5 %. Analysis of combined infections in dogs revealed the following combinations: Giardia spp. and Cryptosporidium spp. (35.5 %) larvae of S. stercoralis sp. and Giardia spp. (32.3 %), T.canis and Giardia spp. (22.6 %), T.canis and Cryptosporidium spp. (6.6 %), T.canis and S.stercoralis and (3.2 %), respectively. In cats, only two coinfections by Giardia spp. and Cryptosporidium spp. (58.3 %), and T.cati with Giardia spp. (41.7 %) were noticed. Further research is needed to study the spread of parasitic diseases in pet animals. The data will improve countermeasures to prevent these diseases' spread among animals and humans.