infectious diseases
Plague and Other Yersinia Infections
Symptoms and Signs of Plague
Plague has several distinct clinical manifestations: Bubonic plague (most common) Pneumonic plague (primary or secondary) Septicemic plague Pestis minor Pharyngeal plague and plague meningitis are less common forms. In bubonic plague, the most common form, the incubation period is usually 2 to 5 days but varies from a few hours to 12 days. Onset of fever of 39.5 to 41°C is abrupt, often with chills. The pulse may be rapid and thready; hypotension may occur. Lymph nodes that drain the site of inoculation by the bacteria become enlarged and tender (buboes) and appear shortly after the fever. The femoral or inguinal lymph nodes are most commonly involved, followed by axillary, cervical, or multiple nodes. Typically, the nodes are extremely tender and firm, surrounded by considerable edema. They may suppurate in the 2nd week. The overlying skin is smooth and reddened but often not warm. A primary cutaneous lesion (papule, pustule, ulcer, or eschar) may form at the site of the flea bite. The patient may be restless, delirious, confused, and uncoordinated. The liver and spleen may be enlarged. Because the bacteria can spread through the bloodstream to other parts of the body, bubonic plague may be complicated by hematogenous (secondary) pneumonic plague. The case fatality rate for untreated patients with bubonic plague is about 60%; most deaths result from septicemia in 3 to 5 days. A bubo, an enlarged, tender, firm lymph node, is caused byYersinia pestis(plague) infection. This image shows a femoral bubo. Image courtesy of Drs. Margaret Parsons and Karl F. Meyer via the Public Health Image Library of the Centers for Disease Control and Prevention. A bubo, an enlarged, tender, firm lymph node, is caused byYersinia pestis(plague) infection. This image shows a swollen inguinal bubo. Image courtesy of the Public Health Image Library of the Centers for Disease Control and Prevention. A bubo, an enlarged, tender, firm lymph node, is caused byYersinia pestis(plague) infection. This image shows an axillary bubo. Image courtesy of Drs. Margaret Parsons and Karl F. Meyer via the Public Health Image Library of the Centers for Disease Control and Prevention. Primary pneumonic plaguehas a 2- to 3-day incubation period, followed by abrupt onset of high fever, chills, tachycardia, chest pain, and headache, often severe. Cough, not prominent initially, develops within 24 hours. Sputum is mucoid at first, rapidly develops blood specks, and then becomes uniformly pink or bright red (resembling raspberry syrup) and foamy. Tachypnea and dyspnea are present, but pleuritic chest pain is not. Signs of consolidation are rare, and rales may be absent. Secondary pneumonic plagueis more common than primary and results from hematogenous dissemination of organisms from a bubo or other foci of infection. Most untreated patients with pneumonic plague die within 48 hours of symptom onset. Septicemic plague may occur with the bubonic form or without the bubonic form (called primary septicemic plague) as an acute, fulminant illness. Abdominal pain, presumably due to mesenteric lymphadenopathy, occurs in 40% of patients. Disseminated Intravascular Coagulation (DIC) , gangrene of the extremities (hence, the name Black Death), and multiorgan failure eventually develop. Septicemic plague may be fatal before bubonic or pulmonary manifestations predominate. Pestis minor, a more benign form of bubonic plague, usually occurs only in endemic areas. Lymphadenitis, fever, headache, and prostration subside within a week. 