STRONGYLOIDES STERCORALIS INFECTION IN TWO DOGS FROM THE SAME KENNEL

Strongyloides stercoralis is a worldwide zoonotic parasite, infecting men, dogs and cats (1) . It is the unique among nematodes of veterinary importance that has both a free-living cycle and a parasitic one (2). The parasitic phase is supported entirely by females, localized in the small intestine. In the dog S. stercoralis infection occurs mostly via penetration of skin and mucosal surfaces or by transmammary transmission. Autoinfection occurs as well and, if it is long-lasting in immunosuppressed hosts, massive hyperinfection and even disseminated infection by migrating larvae may occur (3). Autoinfection can induce persistent strongyloidosis in absence of reinfestation from outside. Clinical disease varies from inapparent to severe enteritis and pneumonia to sudden death (2). The in vivo diagnosis is difficult due to the low sensitivity of traditional parasitological methods and it is based on larvae detection in faecal samples collected from rectal ampulla to overcome the morphological similarities with environmental free living nematode larvae. S. stercoralis is the only Strongyloides species described in naturally infected dogs. Two clinical cases are described. Two male adult dogs from the same kennel were presented with an history of chronic severe diarrhea, weight loss, depression (dog1) and of reduced appetite, diarrhea and weight loss (dog2). At clinical examination dog1was very thin (BCS2) and depressed; in dog 2 (BCS4) a mass was clinically revealed in medium abdomen and its gastrointestinal origin at ileocecocolic junction was identified by ultrasound. A final diagnosis of linfoma was reached by cito/hystology. Dog1 naturally died after 24 hours from presentation, dog2 was treated for infection before surgery and monitored. The laboratory alterations common to both dogs at the time of presentation were: leukocytosis, mild anemia, hypoproteinemia and increase of alpha2 fraction at serum proteins electrophoresis. Eosinophilia was not detected. Diagnosis of S. stercoralis infection was performed by larvae detection and identification in faecal samples collected from ampolla (direct and/or Baermann test) and subsequently by the finding of adult females after scraping of the intestinal mucosa at post-mortem examination. The histological features showed in dog1: hemorrhagic parasitic enteritis of moderate-to-severe degree, with the presence of inflammatory linfoplasmocitic exudates in the lamina propria; several adult parasites localized in proximity of the duodenal papilla; a moderate pulmonary atelectasis associated with a moderate interstitial congestion. Dog2 was treated with febendazole 50 mg/kg/die and metronidazole (25 mg/kg/bid) for 5 consecutive days and monitored for the following ten days. Multiple fecal pool samples from dogs living in same kennel have been examined using Baermann tecnique living negative results to S. stercoralis larvae detection. The clinical cases are discussed focusing on pathogenetic hypothesis (hyperinfection vs patologia concomitante). For authors knowledge S. stercoralis infection in dogs have never been reported in Italy. S. stercoralis is a zoonotic parasite and despite natural transmission between dog and man has been rarely reported (2) the potential role of the dogs as source of human infections ha sto be taken in mind, particularly in kennel where il sovraffollamento e le ridotte condizioni igieniche risultano fattori predisponenti al perpetuarsi dell’infezione. 1Ferreira JA et al., Vet. Parasitol. 2006, 136: 137-145. 2Dillard KJ et al., Acta Vet Scan. 2007, 49:37. 3Shoop WL et al., J. Parasitol. 2002, 88: 536-539.