York County Medicine Summer 2020 - 29

YO R K C O M E D S O C . O R G

FEATURE:

EPIDEMICS
By: Jonathan Rhoads, MD

I

nfectious diseases have always been with us. They are described
in the Old Testament. From time to time they have had a
major impact on society and military campaigns, but so far,
the human race has survived to become one of the most successful
species on earth. That is not to say that individual societies
have not been disastrously affected by epidemics from time to
time. I grew up in a medical family, my brother is Professor of
Epidemiology, and I graduated from medical school in 1964. This
article on epidemics is based on remembrances I have from my
several walks of life and news reports about the current epidemic.
In writing this article, I am responding to a request for a
contribution to this issue. I hope to put the COVID-19 epidemic
in some perspective.
In the Old Testament one of the plagues describes people
getting "buboes in their private parts," probably enlarged inguinal
lymph nodes, which is consistent with bubonic plague (BP). It
is caused by a bacterium, Pasteurella pestis. It is carried by fleas
and rats. A novel by Albert Camus entitled "Plague" begins with
finding a dead rat, and deals with an epidemic of it. In the middle
ages repeated episodes of BP were recorded, and were associated
with decimating populations. That means killing 90% of the
people. It was known as the "Black Death." In medical school it
was considered to be too dangerous for medical students to have
anything to do with. This author has never seen a case and does
not remember hearing about an epidemic in modern times.
Smallpox has been a scourge of mankind for centuries. I was
taught that it is the most infectious disease known. It is caused
by a virus, Variola, and human beings are the only known host for
it. The mortality rate was 30-40%. It is characterized by a rash
in which the skin lesions become infected and leave scars behind
when they heal. Some nineteenth century novels will describe
characters in part by noting a pock marked face. They would be

smallpox survivors. It was responsible for the deaths of many
more soldiers than died in battle. In the 1790s a British physician,
Edward Jenner, noted that milkmaids did not get smallpox, but
they did get cow pox. He found that by inoculating people
with cow pox (Vaccinia) he could prevent smallpox. Thus began
immunizations against infectious diseases. Vaccination caught
on rapidly and was practiced widely. The last case of smallpox in
USA was in 1947. A worldwide vaccination campaign led to the
eradication of smallpox by 1980. A major triumph for mankind.
We no longer vaccinate against smallpox, and have not had a
recurrence.
Tuberculosis (TB) has been the cause of a great deal of
premature mortality over the years. It was well known in 19th
century Europe: Keats, Schubert, one of the Bronte sisters, and
many others died of it. The heroine of two of the most frequently
performed (19th century) operas* succumb to it at the end of the
opera. I knew a man who was descended from the lone surviving
child of a family of twelve children, eleven of whom died of TB
from the family's tuberculous cow. We pasteurize milk (heat it to
160 degree for about 45 minutes) which kills the TB. The British
veterinarian-author James Herriot writes about examining cows
for TB in Yorkshire. In the 19th and early 20th centuries sanitaria
were established to segregate persons infected with TB from
society. Persons admitted to such sanitaria might stay there for
months or years. TB is caused by a slow-growing bacterium (M.
tuberculosis) which most commonly affects the lungs, producing
infiltrates which cavitate, and it produces further deterioration in
lung function. It can affect any part of the body. Many persons
have been exposed to it and may harbor it. If their immune
system is vigorious they do not get clinical disease. But if the
immune system is compromised by medication or in other ways,
the TB grows. Surveillance for TB is done by skin tests and chest
X-rays. Before antibiotics, cavitary TB was treated by collapsing
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York County Medicine Summer 2020

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