Differentials
Gram-negative sepsis
SIGNS / SYMPTOMS
Symptoms and signs may be similar. Absence of painful buboes in gram-negative sepsis. Secondary septicaemic plague after pneumonic plague is associated with haemoptysis and pleuritic chest pain.
INVESTIGATIONS
Blood cultures positive for gram-negative bacilli other than Yersinia pestis.
Bacterial pneumonia
Cat scratch disease
SIGNS / SYMPTOMS
Indolent course without significant systemic features.
INVESTIGATIONS
Positive serology for Bartonella henselae.
Bacterial lymphadenitis
SIGNS / SYMPTOMS
Lymphadenitis due to streptococci or staphylococci may be associated with lymphangitis or cellulitis. Lymph nodes are more likely to be fluctuant.
INVESTIGATIONS
Blood cultures or other clinical samples positive for Staphylococcus aureus or streptococcal species.
Mycobacterial infection
SIGNS / SYMPTOMS
Clinical course is indolent. Lymphadenitis tends to be non-tender.
INVESTIGATIONS
Positive cultures for Mycobacterium species.
Tularaemia
SIGNS / SYMPTOMS
Glandular, typhoidal, and pneumonic presentations may be difficult to distinguish clinically from plague.
The two conditions co-exist in many endemic areas worldwide.
INVESTIGATIONS
Positive cultures for Francisella tularensis (laboratory is informed if tularaemia suspected).
Positive serology for F tularensis.
Rocky Mountain spotted fever and other rickettsial infections
SIGNS / SYMPTOMS
A more indolent course is typical with less systemic toxicity. Headache is often a prominent feature. Generalised rash is frequent, which may be petechial or maculopapular.
INVESTIGATIONS
Rickettsial infection may be confirmed serologically.
Infectious diarrhoea (yersiniosis)
SIGNS / SYMPTOMS
Differential diagnosis is broad, as various bacteria, parasites, and viruses cause diarrhoea.
INVESTIGATIONS
Presence of specific infectious agent on stool or serological testing.
Acute appendicitis (yersiniosis)
SIGNS / SYMPTOMS
Absence of diarrhoea and/or bloody stools. Usually right lower quadrant tenderness.
INVESTIGATIONS
Abdominal and pelvic CT scan shows abnormal appendix. Ultrasound may be useful if CT is not available or patient is pregnant.
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