Microbiology, 2021

1110 26 • Nervous System Infections
vaccine against Hansen’s disease because both diseases are caused by species of Mycobacterium. The
effectiveness of this method is questionable, however, since it appears that the vaccine works in some
populations but not in others.
Figure 26.11
(a) The nose of a patient with Hansen’s disease. Note the lepromatous/multibacillary lesions around the nostril. (b)
Hansen’s disease is caused by Mycobacterium leprae, a gram-positive bacillus. (credit a, b: modifications of work by the Centers for
Disease Control and Prevention)
CHECK YOUR UNDERSTANDING
• What prevents the progression from tuberculoid to lepromatus leprosy?
• Why does Hansen’s disease typically affect the nerves of the extremities?
Eye on Ethics
Leper Colonies
Disfiguring, deadly diseases like leprosy have historically been stigmatized in many cultures. Before
leprosy was understood, victims were often isolated in leper colonies, a practice mentioned frequently in
ancient texts, including the Bible. But leper colonies are not just an artifact of the ancient world. In Hawaii,
a leper colony established in the late nineteenth century persisted until the mid-twentieth century, its
residents forced to live in deplorable conditions. 18 Although leprosy is a communicable disease, it is not
considered contagious (easily communicable), and it certainly does not pose enough of a threat to justify
the permanent isolation of its victims. Today, we reserve the practices of isolation and quarantine to
patients with more dangerous diseases, such as Ebola or multiple-drug-resistant bacteria like
Mycobacterium tuberculosis and Staphylococcus aureus. The ethical argument for this practice is that
isolating infected patients is necessary to prevent the transmission and spread of highly contagious
diseases—even when it goes against the wishes of the patient.
Of course, it is much easier to justify the practice of temporary, clinical quarantining than permanent
social segregation, as occurred in leper colonies. In the 1980s, there were calls by some groups to establish
camps for people infected with AIDS. Although this idea was never actually implemented, it begs the
question—where do we draw the line? Are permanent isolation camps or colonies ever medically or socially
justifiable? Suppose there were an outbreak of a fatal, contagious disease for which there is no treatment.
Would it be justifiable to impose social isolation on those afflicted with the disease? How would we balance
the rights of the infected with the risk they pose to others? To what extent should society expect individuals
to put their own health at risk for the sake of treating others humanely?
18 National Park Service, “A Brief History of Kalaupapa,” Accessed February 2, 2016. http://www.nps.gov/kala/learn/historyculture/
a-brief-history-of-kalaupapa.htm.
Access for free at openstax.org.