Animal bites, arthropod bites and zoonoses: Viva

Branch 1: Recognising the two linked risks

The candidate should immediately separate the two children into two distinct risk profiles. The boy has a cat bite to the hand, which is the bite most likely to become infected because a cat's long narrow teeth produce a deep puncture that seals over and seeds Pasteurella and oral anaerobes into the tendon sheath or joint capsule. The girl has a scratch from a flying fox, which in Australia is an Australian bat lyssavirus exposure until public health clears it, regardless of how trivial the scratch appears. [1]

The candidate should state that the brother's wound needs prophylaxis and careful assessment for deep structure involvement, while the sister needs urgent rabies and Australian bat lyssavirus post-exposure prophylaxis begun without delay. Both children also need a tetanus assessment, and the candidate should frame the whole encounter around a structured exposure history covering the animal, the mechanism, the geography, the time elapsed, and each child's vaccination and immune status. [2]

Branch 2: Wound care, closure, and the antibiotic decision

The examiner will probe the boy's wound management. The candidate should describe copious high-pressure normal saline irrigation and debridement of any devitalised tissue, and should be explicit that a hand bite is never primarily closed because closure traps infection in a tissue plane millimetres from the tendon sheath and joint. The candidate should examine for pain on passive movement, reduced range, and tendon sheath tenderness, and should request hand-surgery review if these are present. [1]

On antibiotics, the candidate should give prophylactic amoxicillin-clavulanate because this is a cat bite of the hand, which is one of the wounds for which prophylaxis is always indicated alongside dog bites with deep puncture or crush, immunocompromised hosts, and bites needing closure or debridement. The candidate should explain that amoxicillin-clavulanate is preferred because it covers Pasteurella, anaerobes, and Capnocytophagus in a single agent, and should give a five-day oral course with review at twenty-four to forty-eight hours. [3]

Branch 3: The rabies and lyssavirus decision and safety-netting

The examiner will turn to the sister. The candidate should state that a flying fox scratch in Australia is treated as Australian bat lyssavirus exposure, that lyssavirus is clinically indistinguishable from rabies and almost universally fatal once symptomatic, and that post-exposure prophylaxis virtually eliminates the risk when given promptly. The candidate should describe thorough wound washing, infiltration of rabies immunoglobulin into and around the wound, and a rabies vaccine course on days zero, three, seven, and fourteen, begun before public health confirmation. [2]

The candidate should close by addressing tetanus prophylaxis for both children based on their vaccination status, public health notification of the bat exposure, and clear written safety-netting advice for the brother on the signs of spreading infection, reduced movement, and fever that mandate return. The examiner will reward a candidate who frames both children with the same disciplined checklist of exposure history, wound care, targeted prophylaxis, and the rabies and tetanus decision. [2]