Introduction

There are natural foci of plague infection involving rodents in many parts of the world. Wild rodent plague is present in central, eastern and southern Africa, South America, the western part of north America and in large areas of Asia.

In some areas, contact between wild and domestic rats is common, resulting in sporadic cases of human and occasional outbreaks.

Causative agent: The plague bacillus, Yersinia pestis

Transmission: Transmitted by fleas from rodents to other animals and to humans. Direct person-person transmission does not occur except in the case of pneumonic plague, when respiratory droplets may transfer the infection from the patient to others in close contact.

Plague can also be spread by handling infected tissues, or from contact with discharge or pus from an infected animal

Incubation period: 1 to 7 days

Risk for travelers generally is low. However travellers in rural areas of plague endemic regions may be at risk, particularly if camping or hunting or if contact with rodents takes place.

Sign & Symptoms

Generally the sign and symptoms are fever, cough, painful swelling in the groins, neck and armpits and vomiting.

Plague occurs in 3 main clinical forms:

Bubonic plague: Usually results from the bite of infected fleas. Lymphadenitis develops in the drainage lymph nodes, with the regional lymph nodes most commonly affected. Swelling, extremely painful and suppuration of the lymph nodes produces the characteristic plague buboes

Septicaemic plague: May develop from bubonic plague or occur in the absence of lymphadenitis. Dissemination of the infection in the bloodstream results in meningitis, endotoxic shock and disseminated intravascular coagulation (DIVC).

Pneumonic plague: may result from secondary infection of the lungs following dissemination of plague bacilli from other body sites. It produces severe pneumonia. Direct infection of others may result from transfer of infection by respiratory droplets, causing primary pulmonary plague in the recipients.

Complication

Without prompt and effective treatment, 50-60% of cases of bubonic plague are fatal.

Untreated septicaemic plague results in meningitis, endotoxic shock and DIVC and while pneumonic plague produces severe pneumonia.

Treatment

Specific treatment: Streptomycin is the drug of choice. Others like gentamycin, tetracyclines and chloramphenicol are the alternatives.

Prevention & Precautions

Precautions

If you are visiting a p lague infected area:

• Avoid any contact with live or dead rodents
• Avoid overcrowded places
• Avoid flea bites by the use of repellents and insecticides
• Avoid handling dead rats and report to the health authorities any sighting of dead rats
• If you are in contact with an infected person avoid coming into contact with body discharges and seek early treatment
• Appropriately store and dispose your food, garbage and refuse to prevent access to food and shelter by domestic rats.

References organisation/ support

International Travel & Health, WHO 2006

Control of Communicable Diseases Manual, 18th Edition by David L. Heymann, MD, Editor, 2004