Scrofula, as Webster 1913 implies, is now known to be a form of tuberculosis, namely, "tuberculous lymphadenitis." The name "scrofula" come from the Latin word scrofulae, for glandular swelling, and the word scrofa, which is a breeding sow. The disease was so named because it was thought to be similar to an ailment affecting pigs.
The disease has been known throughout history. In 400 B.C., Herodotus suggested that people with a scrofula-like disease be quarantined2. The node London Causes of Death in 1700 lists that eighty-three people died of "evil," noting that "this probably refers to a disease known as "the King's Evil" or as scrofula." The disease was known as "the King's Evil" as early as 496 A.D., as it was believed that it could be cured by "the royal touch." Kings often held ceremonies in which they would touch those afflicted with scrofula to cure them2. In Act IV, scene 3 of Shakespeare's Macbeth, Malcom explains the ceremony to Macduff:
Infection and Symptoms
'Tis call'd the evil:
A most miraculous work in this good king;
Which often, since my here-remain in England,
I have seen him do. How he solicits heaven,
Himself best knows: but strangely-visited people,
All swoln and ulcerous, pitiful to the eye,
The mere despair of surgery, he cures,
Hanging a golden stamp about their necks,
Put on with holy prayers: and 'tis spoken,
To the succeeding royalty he leaves
The healing benediction. With this virtue,
He hath a heavenly gift of prophecy,
And sundry blessings hang about his throne,
That speak him full of grace.
Scrofula is now known to be caused by a mycobacteria infection, probably caused by inhalation of Mycobacterium tuberculosis, or Mycobacterium scrofulaceum and Mycobacterium avium in children. The bacterial infection spreads, causing enlargements of the lymph nodes in the neck. If the infection is not treated the nodes may ulcerate, causing draining sores. Symptoms include painless swelling of lymph nodes in the neck, ulceration, enlarged lymph nodes elsewhere in the body, fevers, chills, sweats, and sometimes weight loss.
Treatment usually consists of several months of antibiotic treatment, often using several antibiotics to ensure that the bacterium does not become antibiotic-resistant. Surgery is only needed in cases where other treatment has not proved effective.
HIV infection results in increased likelihood of developing scrofula. Otherwise, your chance of getting a tuberculosis infection in your lymph nodes is low, although it is much higher in developing countries.
1 - http://www.nlm.nih.gov/medlineplus/ency/article/001354.htm
2 - http://www.mgh.harvard.edu/depts/id/images/scrofula.pdf