Plague

Generalities
Agent	Bacteria: Yersinia pestis
Incubation period	1-7 days
Period of transmissibility	- Pneumonic plague: during the active phase - Bubonic phase (rare): if contact with pus from suppurative buboes
Reservoir	Wild rodents, lagomorphs (rabbits, hares), wild carnivores and domestic cats
Modes of transmission	- Most common via bite of infected rodent fleas (Xenopsylla cheopis): 1) Wild rodent fleas linked to zoonotic/sylvatic cycle; 2) Commensal rodent fleas infected by peri-domestic mammals and linked to poor hygiene - Handling infected animals - Contact with infected cats via bites or droplets - Laboratory exposure - Person-to-person: 1) Airborne droplets from patients with pneumonia or pharyngitis plague; 2) Pulex irritans fleas (human flea) - Aerosol: deliberate use
Clinical presentation	- Bubonic plague (90%: febrile lymph nodes that become swollen, inflamed, tender and may suppurate. Inguinal area is more concernet than axillary and cervical areas. Complications: septicemic plague, meningitis, disseminated intravascular coagulation, pneumonia, mediastinitis, pleural effusion, endotoxin shock. Case fatality is 50-60% if untreated. - Secondary pneumonic plague: source of primary pneumonic or pharyngitis plague, causing localized outbreaks. Fatal if untreated.
Resources
Case definition	MOPH circular no. 113 (2006)
Forms	- General reporting form - Plague investigation form
Data	Refer to "Surveillance Data"