Introduction

Australia, with its diverse climate and geography, presents a unique set of infectious diseases that medical professionals must be well-versed in. For candidates preparing for the Australian Medical Council (AMC) exams, understanding these infections is crucial for clinical practice. This guide highlights high-yield infections commonly encountered in Australia, their epidemiology, clinical features, diagnosis, and management strategies.

1. Respiratory Infections

1.1 Influenza

Influenza is a seasonal viral infection caused by influenza A and B viruses. The flu season in Australia typically peaks between May and September.

Clinical Features: Fever, myalgia, sore throat, cough, and fatigue.

Diagnosis: Rapid antigen tests, PCR testing.

Management: Supportive care, antiviral medications (e.g., oseltamivir) in high-risk patients.

Prevention: Annual influenza vaccination, good hand hygiene, and respiratory etiquette.

1.2 Pneumonia

Community-acquired pneumonia (CAP) is a leading cause of morbidity and mortality in Australia, commonly caused by Streptococcus pneumoniae, Haemophilus influenzae, and atypical pathogens.

Clinical Features: Fever, productive cough, pleuritic chest pain, dyspnea.

Diagnosis: Chest X-ray, sputum culture, blood cultures in severe cases.

Management: Antibiotics (amoxicillin, doxycycline, or macrolides for mild cases; ceftriaxone plus azithromycin for severe cases).

2. Vector-Borne Infections

2.1 Dengue Fever

Dengue virus is transmitted by Aedes mosquitoes and is prevalent in northern Australia, particularly in Queensland.

Clinical Features: High fever, severe myalgia, retro-orbital pain, rash, and potential progression to dengue hemorrhagic fever.

Diagnosis: Dengue NS1 antigen test, PCR, or serology.

Management: Supportive care with fluid resuscitation and pain management (avoid NSAIDs).

Prevention: Mosquito control, use of insect repellents, and protective clothing.

2.2 Ross River Virus

A mosquito-borne alphavirus causing polyarthritis, more common in rural and coastal regions.

Clinical Features: Polyarthritis, rash, low-grade fever, and fatigue.

Diagnosis: Serological testing (IgM and IgG antibodies).

Management: Supportive care, NSAIDs for joint pain.

Prevention: Mosquito bite prevention strategies.

3. Gastrointestinal Infections

3.1 Campylobacter and Salmonella Infections

These are common causes of bacterial gastroenteritis in Australia, usually linked to contaminated food and water.

Clinical Features: Watery or bloody diarrhea, abdominal cramps, fever, nausea.

Diagnosis: Stool culture or PCR testing.

Management: Supportive care (oral rehydration), antibiotics (azithromycin for severe cases).

3.2 Norovirus

A leading cause of viral gastroenteritis outbreaks in Australia, often associated with cruise ships and aged care facilities.

Clinical Features: Acute-onset vomiting, watery diarrhea, abdominal cramps.

Diagnosis: Clinical diagnosis, stool PCR in outbreak settings.

Management: Hydration therapy, symptomatic treatment.

4. Sexually Transmitted Infections (STIs)

4.1 Chlamydia

Chlamydia trachomatis is the most commonly reported STI in Australia, particularly among young adults.

Clinical Features: Often asymptomatic; can cause urethritis, cervicitis, pelvic inflammatory disease (PID).

Diagnosis: NAAT (nucleic acid amplification test) from urine or swab samples.

Management: Azithromycin (single dose) or doxycycline (7-day course).

4.2 Syphilis

Syphilis cases have been increasing in Australia, particularly among men who have sex with men (MSM) and Indigenous populations.

Clinical Features: Painless chancre (primary stage), maculopapular rash (secondary stage), neurosyphilis (late stage).

Diagnosis: Serology (RPR, TPPA tests), dark-field microscopy.

Management: Penicillin G injections.

5. Zoonotic Infections

5.1 Q Fever

Caused by Coxiella burnetii, Q fever is linked to livestock exposure (cattle, sheep, goats).

Clinical Features: Fever, pneumonia, hepatitis.

Diagnosis: Serology (IgM, IgG antibodies), PCR.

Management: Doxycycline for 2 weeks.

Prevention: Vaccination for high-risk individuals (farmers, abattoir workers).

5.2 Hendra Virus

A rare but deadly virus transmitted from horses to humans.

Clinical Features: Flu-like symptoms, progressing to pneumonia or encephalitis.

Diagnosis: PCR testing, serology.

Management: Supportive care, experimental monoclonal antibodies.

6. Fungal Infections

6.1 Tinea (Dermatophytosis)

A common superficial fungal infection affecting skin, nails, and hair.

Clinical Features: Itchy, scaly lesions with central clearing (ringworm), nail thickening, scalp scaling.

Diagnosis: Clinical appearance, KOH microscopy.

Management: Topical antifungals (clotrimazole, terbinafine), oral antifungals for severe cases.

6.2 Candidiasis

Oral and vaginal candidiasis are common in immunosuppressed individuals and those on antibiotics.

Clinical Features: White plaques in the mouth, vulvovaginal itching and discharge.

Diagnosis: Clinical diagnosis, fungal culture.

Management: Fluconazole (oral), nystatin (topical for oral thrush).

7. Parasitic Infections

7.1 Strongyloidiasis

Caused by Strongyloides stercoralis, this parasite is endemic in Indigenous Australian communities.

Clinical Features: Chronic skin rash, gastrointestinal symptoms, hyperinfection in immunosuppressed individuals.

Diagnosis: Serology, stool microscopy.

Management: Ivermectin.

Prevention: Improved sanitation and hygiene.

Conclusion

Understanding these high-yield infections is essential for medical professionals in Australia, particularly for AMC exam candidates. This guide provides an overview of the epidemiology, clinical features, diagnosis, and management of common infectious diseases. Preventive measures, including vaccination, hygiene, and public health initiatives, play a crucial role in controlling the spread of infections in Australia. Mastering these infections will not only help in exam preparation but also enhance clinical practice in an Australian healthcare setting. Read more blog…