IN HUMANS
PREVALENCE AND RISK FACTORS • Hookworms are the most common cause of cutaneous larva migrans (CLM) in humans, characterised by percutaneous penetration and migration of hookworm larvae in the skin. • There is no human prevalence data in Australia for zoonotic hookworm infections, however reports typically emanate from wet tropical areas. • There is no difference in probability of infection between veterinary staff, the general public or children that play in parks. A key factor in transmission is contact with moist sand and soil, particularly beach environments. CLINICAL DISEASE • All animal hookworms are zoonotic and capable of producing CLM. “Ground itch”, consisting of a self-limiting pruritic papular rash, is the most common presentation at the site of percutaneous penetration of larvae. • “Creeping eruptions”, the typical highly pruritic and chronic migrating linear serpiginous lesions, are produced by A. braziliense and usually require medical intervention. 10 In Australia this is usually considered a travel-associated disease, with most cases diagnosed in travellers returning from the wet tropics where A. braziliens e is endemic. 10,11 • Whilst most hookworm species cannot complete their life cycle in people, A. ceylanicum can produce patent infections in humans and may result in diarrhoea (sometimes haemorrhagic), severe abdominal pain, fever, peripheral eosinophilia and anaemia. 12 Locally acquired cases of A. ceylanicum have been reported in people with gastrointestinal disturbances in Western Australia. 13 Ancylostoma ceylanicum is considered an emerging public health risk in northern tropical Australia, being found in areas frequented by tourists. 6 • The global disease burden of hookworm is high, with an estimated 500 million people affected. 1 Recent studies
Cutaneous larva migrans caused by migration of larvae through human skin
in Australia’s pacific neighbour, the Solomon Islands, demonstrated zoonotic ancylostomiasis caused by patent A. ceylanicum to be as high as 18.2%, while molecular-based surveys in Asia report between 6% and 23% of total patent hookworm infections are due to A. ceylanicum. 14,15 • Hookworm infection is also a known cause of maternal anaemia in humans. Intestinal hookworm infection can result in iron deficiency anaemia and malnutrition in pregnant women and children. During pregnancy, hookworm infection has been associated with low birthweight and poor neonatal outcomes, including negative consequences for the cognitive and motor development of infants. 16,17 The public health impact of zoonotic infection with A. ceylanicum on a population scale are largely unexplored. • A. caninum is a well-recognised agent of eosinophilic enteritis and aphthous ileitis in tropical Australia. Although most infections are asymptomatic, a single immature adult worm residing in the small intestine is capable of eliciting abdominal pain, intestinal bleeding, diarrhoea and weight loss. 18 • More recently, rare patent infections of A. caninum have also been reported in humans. 19,20
KEY CONSIDERATIONS 1. Observing good hygiene measures and avoiding skin contact with contaminated soil and sand is recommended. 2. Individuals with occupations that require prolonged contact with moist soil should wear protective clothing, including shoes and gloves. 3. Veterinarians and public health workers should educate dog owners regarding the potential risks of improper parasite control in dogs.
At least monthly deworming of dogs and cats is recommended to reduce environmental
contamination and minimise zoonotic risk.
CONTENTS
Companion Animal Zoonoses Guidelines 52
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