IN ANIMALS continued
CLINICAL DISEASE • The clinical features of infestation in puppies (as early as ten days old for A. caninum ) may include
• Adult hookworms live in the small intestine. Eggs are excreted in the faeces where they embryonate and after two moults develop into infective third stage larvae. Larvae entering through the skin undergo pulmonary migration, are swallowed, and develop to adults in the gastrointestinal tract. Infections acquired orally undergo direct development to adults in the gastrointestinal tract. • The prepatent period depends on the route of infection and species of hookworm, varying from two to four weeks. PREVALENCE AND RISK FACTORS • In an Australia-wide prevalence study, hookworm was identified in 6.7% of dogs and 1.4% of cats, with a significantly higher prevalence in the Northern Territory and Queensland. 3 A 2017 study confirmed 25% of domestic dogs in central Queensland to be infected with hookworms. 4 • In Indigenous communities of the wet tropics of northern Queensland, A. caninum is the most common hookworm of domestic dogs and wild dingoes, with a prevalence of 92% and 100% respectively. 5 Ancylostoma ceylanicum is the second most prevalence hookworm species in this area, reported in 22% of domestic dogs and 11% of dingoes. 5,6 • More recently, a 2020 study of dogs living in remote communities of the Northern Territory detected a prevalence of A. caninum of 31% . 7 • Hookworms affect both dogs and cats, with stray animals, dogs in animal shelters and hunting animals more commonly infested. Puppies and younger dogs are more susceptible to heavy worm burdens owing to lowered age- and exposure- related immunity.
acute haemorrhagic diarrhoea (melena or haematochezia), pallor, hypoproteinaemia and death. 2 Other signs include general loss of condition with an ongoing parasite burden (e.g. failure to thrive, anaemia), abdominal distension, chronic diarrhoea and more rarely, skin or respiratory conditions. 2 • In adult dogs, acute infections may also result in haemorrhagic enteritis, however age and exposure-related immunity to trickle infections, which is not absolute, usually results in a chronic subclinical non-regenerative iron deficiency anaemia. 2 • Clinical signs in cats are similar to those in dogs, but generally less severe as cats typically have lower hookworm burdens and A. tubaeforme is a less voracious blood feeder than hookworm species infesting dogs.
DIAGNOSIS • Ancylostomiasis should be considered as a differential diagnosis in dogs and cats with
intestinal disorders and weight loss. A definitive diagnosis can only be made by the detection of strongyle eggs via standard faecal flotation. • In acute disease, especially in puppies, faecal antigen testing for intestinal parasites in combination with faecal flotation has been shown to be of benefit, given immature worms may still cause clinical signs prior to eggs being shed in the faeces. • Alternatively, a presumptive diagnosis can be made if a rapid resolution of clinical signs is observed in response to treatment with an efficacious anthelmintic, accompanied by supportive care.
TRANSMISSION
• Infection in humans is either via direct skin penetration by infective larvae (typically by walking or lying barefoot on sandy beaches, contaminated soil or sandy areas) or via ingestion of larvae on contaminated surfaces and food. • Shed eggs are not immediately infectious. The hatched non-infective larvae develop in faeces or soil to the infective third stage in 5-10 days. 8 • Hookworm larvae can survive and remain infective for several months in warm and humid environments if protected from direct sunlight and desiccation. 9
CONTENTS
51 Companion Animal Zoonoses Guidelines
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