Zoonoses often have both an acute and a chronic form.

For patients presenting with any condition, accurate diagnosis and the possibility of treatment relies on a comprehensive history and examination.

A common, although by no means universal, presentation in zoonotic disease is acute febrile illness that may be ‘flu-like’ and may or may not have respiratory symptoms.

Some zoonoses have additional clinical signs that suggest the most likely causative organism.

Probability diagnosis is influenced by history of geography, exposure to species and the patient’s activities.

History for patients with chronic debilitating conditions may well disclose exposure to animals and thus suggest a zoonosis as the cause of their symptoms.

Proper establishment of pre-test probabilities before ordering investigations is essential for avoiding harms through false positives/negatives and unnecessary financial and other costs to both the patient and the health system.

Other zoonoses that can produce symptoms similar to Brian’s include:

1. Scrub typhus
   

   Frances, S. (2011). Rickettsial Diseases of Military Importance: An Australian Perspective. Journal of Military and Veterans' Health, 19(4).
   View article
2. Queensland tick typhus
   

   Department of Health, Victoria. (2015). Rickettsial infections.
   View website
3. Dengue fever
   

   Northern Territory Government. (2021). Dengue fever.
   View website

Leptospirosis and rat bite fever could reasonably be considered in respect of an acute febrile illness following exposure to rats.

Rat bite fever
Rat bite fever is rare within the general population although rat fanciers, particularly those who kiss their rats, are more likely to have the illness.

Leptospirosis
Leptospirosis is more common and can be contracted by people who are exposed not only to infected rats and rat urine (exterminators, commercial cleaners, veterinarians and so on) but also from contact with infected sheep, cattle, domestic and working dogs and contaminated floodwaters, for example.

What signs and symptoms would indicate that a person who had been bitten by a tick had contracted a Rickettsial disease?

The patient will typically complain of:

• Febrile symptoms
• Severe myalgia and/or arthralgia and
• Sudden onset of lethargy

The patient is likely to be febrile, often with a temperature of about 39 to 41°C.

The site of the tick bite will usually be evident, displaying an eschar.

A few days after the onset of symptoms, a rash may appear — widely spaced erythematous macules.

Which invariably fatal zoonoses should be discussed during the travel medicine consult?
Rabies is common in Bali. There have been hundreds of deaths over the last decade. Rabies in conferred by bites or scratches from infected mammals including monkeys and bats as well as dogs and cats.

What preventative measures should Miriam and her husband take?
Immunisation against rabies (e.g. Rabipur®) is an option. The immunisations are not funded, they cost about $110 - $150 each, and three pre-exposure doses are required at 0, 7 and 21-28 days. Many travellers opt to not be immunised and simply avoid being bitten. It is important that irrespective of immunisation status, travellers have an appropriate post-exposure plan.

What action plan should Miriam follow if she is exposed to rabies – dependent upon her immunisation status?
A travelling patient who is exposed to rabies needs to make their way immediately to a US-style hospital (this may require repatriation) to be treated.

If however a patient presents to your surgery following rabies exposure on a recent trip, you may need to discuss with your local public health unit in order to obtain appropriate treatment advice and the rabies vaccinations.

Australian Technical Advisory Group on Immunisation (ATAGI). Rabies and other lyssaviruses. Australian Immunisation Handbook, Australian Government Department of Health, Canberra.
View handbook