By Barry Fox, M.D., University of Wisconsin
When a virus invades the human body, it attacks the body’s cells to survive and replicate. Viruses cause many diseases; however, two diseases—syphilis and typhus—have great historical significance, though they are less common infections today.

What Is Syphilis?
Syphilis is a disease caused by a spirochete. Spirochetes have the same characteristics as bacteria but are different enough biologically—they do not stain with the routine Gram stain.
Two examples include the Borrelia burgdorferi—the Lyme germ—and Treponema pallidum—the syphilis germ. Syphilis is a sexually transmitted disease that is less common today than in the past. However, it has an interesting disease process and provides significant historical lessons.
Learn more about zoonosis—germs leap from animals to humans.
Stages of Syphilis Infection
The syphilis infection is divided into three stages. The primary stage appears as one or more painless, firm, red ulcers called ‘chancres of the skin’ at the site of inoculation. Ulcers most commonly occur on the average of three weeks after exposure, but they generally heal spontaneously.

The secondary stage of syphilis is characterized by a rash and flu-like symptoms and generalized body lymph node enlargement that appears within a couple of months.
This stage also resolves spontaneously without treatment, leaving the infected person completely asymptomatic.
‘Latent syphilis’ is defined as the period after infection when patients show evidence of fighting the disease in their blood but do not demonstrate clinical manifestations of the disease.
The third stage of syphilis, if untreated, occurs 15 to 30 years after the initial infection and can include unusual and bizarre manifestations of the body such as dementia of the brain or ruptured blood vessels leading to death.
Prevalence of Syphilis
Today, there are still around 12 million cases of syphilis around the world, including 17 percent of pregnant women in parts of Africa, which affects both the mothers and their babies.
Its incidence is also directly related to HIV, as there is a two to five percent chance of being infected with both HIV and syphilis since the primary means of transmission is by sexual intercourse.
Learn more about bacteria—heroes and villains.
Origin of Syphilis
Syphilis has a great historical significance as a heated debate has been going on for years regarding the origin of syphilis. Firstly, the disease seems to have originated in a non-sexually related form, often seen in children.
Then it adapted to a venereal form, which means it is primarily associated with sexual intercourse due to changes in behaviors of people at different times in history, and most likely as a means for enhancing its own survival.
Did the Columbus Voyage Bring Syphilis?
Another historical debate is whether the origin of syphilis was in the Old World or the New World—specifically before Columbus sailed to America or after he returned to Europe. Researchers speculated for many years that Christopher Columbus’s voyage brought not only news of the New World, but syphilis as well.
A comprehensive study done by Emory University in 2011 seems to confirm that it came aboard the Nina—the only ship to make it back to Spain.
Girolamo Fracastoro and the Invention of Syphilis
Girolamo Fracastoro, an Italian physician, was credited with naming the disease ‘syphilis’ around 1500. Besides naming the disease, Fracastoro was also the first person to believe that it was due to a seed of contagion.
Once syphilis arrived in Europe, it took only five years for it to become an epidemic. It quickly spread throughout the Old World, Asia, and to every continent except Antarctica.
It was not until 1905 that the specific disease-causing spirochete germ was identified. Syphilis was a devastating disease that killed many thousands of people worldwide.
This is a transcript from the video series An Introduction to Infectious Diseases. Watch it now, Wondrium.
Treatments for Syphilis
Some botanical plants such as wild pansies were considered for the treatment of syphilis. These flowers were thought to possess antimicrobial properties. Another treatment was the use of mercury, which was injected, swallowed, or rubbed on the skin. It was used for treatment up until 1910.
Salvarsan and Neosalvarsan, which were arsenic-based compounds, were used on soldiers who contracted syphilis during World War I.
Fortunately, syphilis, today, is more easily treated with modern antibiotics, especially penicillin.
What Are Rickettsia?

Rickettsia are single-celled organisms that have Gram-negative bacterial structural characteristics but are intracellular rod-shaped parasites, which, like viruses, must live inside cells to survive. They are considered to be a hybrid between a bacterium and a virus.
Rickettsia are usually transmitted by blood-sucking parasites like fleas, lice, and ticks, and they live in the parasite’s intestine. But the parasite does not develop any disease; rather, rickettsia are transmitted by parasite excrement or parasite mouthparts.
Learn more about antibiotics.
Casualties Caused by Typhus
One of the rickettsial diseases was trench fever that was quite common in World War I. It was transmitted by rat fleas. Another rickettsial disease was Rocky Mountain spotted fever that was transmitted by ticks. Typhus, in its normal epidemic form, is caused by Rickettsia prowazekii. It is a deadly, louse-borne disease with a distinctive rash that killed hundreds of thousands of soldiers.
During World War II, there were devastating outbreaks of typhus in concentration camps. One casualty of typhus was Anne Frank.
After the war, the pesticide DDT was used to get rid of the louse population and the number of infections was dramatically reduced.
Thousands of cases occurred in Burundi in Southeast Africa in association with civil wars during the 1990s. Body louse infestation preceded the outbreaks. This was known as Jail Fever and epitomizes the problems with crowding and lack of hygiene.
The clinical manifestations of rickettsial diseases are due to the ability of the rickettsia to multiply inside the endothelial or first layer of cells lining small blood vessels. These infected cells detach from the blood vessels and block blood circulation, eventually leading to deprivation of oxygen in tissues, and cell destruction.
Fortunately, epidemic typhus is now a rare disease due to the advancements in medicine.
Common Questions about Syphilis and Typhus
Syphilis is a disease caused by a spirochete. Spirochetes have the same characteristics as bacteria but are different enough biologically—they do not stain with the routine Gram stain.
Around 1500, Italian physician, Girolamo Fracastoro, discovered and named the syphilis disease.
Rickettsia are single-celled organisms that have Gram-negative bacterial structural characteristics but are intracellular rod-shaped parasites, which, like viruses, must live inside cells to survive.