When we hear “Bubonic Plague,” Europe in the Middle Ages may come to mind. From 1347 to 1350, the Bubonic Plague or the “Black Death” spread across the continent, killing approximately 50 million people, which at the time accounted for more than one-third of Europe’s population. However, the disease is still very much with us, with roughly 600 cases diagnosed annually across the globe.
The countries currently experiencing the largest incidents of plague include Peru, the Republic of Congo, and Madagascar. In the United States, incidents of Plague are largely confined to rural parts of the country, such as a recent report of a child with Bubonic Plague in Idaho.
Bubonic Plague is the result of an infection by a bacterium called Yersinia pestis, which is also the pathogen responsible for Pneumonic Plague and Septicemic Plague. All three versions of the plague begin with headaches, fever, and general malaise. The bacterium generates a number of toxins that contribute to the disease state. As the infection progresses, the symptomology becomes distinctive of the three different forms of the disease.
With Bubonic Plague, there is inflammation of the lymph nodes, which appear swollen and dark and referred to as “buboes.” Persons with the septicemic version exhibit blackened tissue at the sites of infection, where the bacteria has accumulated after passing from the lymphatic system to the bloodstream. The pneumonic form develops in the lungs, where it produces considerable chest pain, coughing, and difficulty breathing. Pneumonic plague is considered the most virulent and potentially lethal without proper diagnosis and treatment.
As early as 1890, the medical community combated plague outbreaks through the administration of a killed bacteria vaccine, though it has not proven as effective as the virulent pneumonic form. More recently, live-attenuated, DNA-based and subunit-based vaccines have been developed.
Typically, one of the licensed plague vaccines is only employed for scientific personnel actively researching Yersinia pestis in the laboratory, particularly those strains exhibiting some antibiotic resistance. It also sometimes used for people in disaster regions where the plague bacterium is endemic. Beyond vaccination, there are several antibiotic regimens that are used against the plague, including streptomycin, gentamicin, tetracycline, doxycycline and chloramphenicol.
Officials describing the recent occurrence with the child in Idaho have not been able to determine whether the boy was infected with the plague bacterium where he resides in Idaho or if the transmission happened during a recent visit to Oregon. In most cases, the disease is transmitted to humans via the bite of a flea that was attached to an infected animal such as squirrels in the United States. Health officials did say that diagnostic assays confirmed the presence of Yersinia pestis in squirrels near the boy’s home in Idaho.
The case is notable in that there have only been two reports of plague in Idaho since 1990, with fewer than eight cases in Oregon. Fortunately, according to the Idaho health department, the antibiotic regimen given the boy appears to have worked and he is recovering at home.
With the increased emergence of antibiotic-resistant bacterial pathogens, diseases such as the Black Plague should be of greater concern to the public. Indeed, incidents of multiple drug resistant (MDR) strains of Mycobacterium tuberculosis, the causative agent of tuberculosis or the White Plague, have been reported from around the globe. There have even been occurrences of extensively drug-resistant (XDR) tuberculosis, where limited to no antibiotic affected the bacterial infection.
Moreover, news stories have recently described England experiencing its first case a new “super strain” of the sexually transmitted disease gonorrhea that is resistant to nearly every known antibiotic regimen. The recent discoveries of new strains of pathogenic bacteria highlight the importance of research and development into new antibiotics and vaccines against these disease-causing agents.