A thirteen-year-old boy walks into a primitive clinic deep within the rain forests of Brazil. After waiting awhile to be seen, a doctor foreign to the boy sees him. The boy complains of lesions in his mouth and in his nose, which have been present for the last month. The doctor asks if he has ever had any other odd bumps that he remembers, and the boy tells him of a painless yellow-red bump that appeared about 5 months earlier. He said that the skin around it was red, and after awhile the bump broke open and was spilling out puss. However, it seemed to disappear after awhile, and everything was fine. A few weeks ago, he seemed to develop more of these mysterious bumps, and they were quite irritating. He told the doctor that the most annoying ones were on the soles of his feet because he was unable to walk long distances without a great deal of pain.
The doctor gave the boy a bottle of penicillin and told him that if he took all of the medicine, the bumps would go away in a week or so. He was diagnosed with Yaws, a disease that is very common in tropical areas, especially if hygiene conditions are poor. It is estimated that this disease affects more than 75 percent of people from some rural communities in tropical areas of the world before they reach the age of 20. As described above, it starts with an initial lesion and then disappears. It reappears later as multiple lesions and left untreated can cause chronic ulcerations or crippling bone and joint lesions. However, it rarely attacks the nervous or cardiovascular system and therefore infrequently causes death in its victims. The disease is caused by a bacterium called Treponema pertenue.
The genus Treponema is from the order Spirochaetales, which includes diverse groups of spiral and actively motile organisms. Aldo Castellani isolated it soon after the discovery of T. pallidum in 1905. The genus Treponema has three species: pallidum, pertenue, and carateum. Treponema pallidum is probably the most famous of the group, being that it causes syphilis. The Treponema are helically coiled organisms having a corkscrew-like shape. They vary in length from 5 to 20 microns and have a thickness in the range of 0.1 to 0.2 micron. They can be described as pale, thin threads (Dubos 578) because of their very poor staining due to their thickness being similar to the resolution of the light microscope. This genus is often examined using darkfield or immunological techniques.
As an order, Spirochetes are considered to be gram negative. Treponema have a very high lipid content, which is unusual for most bacteria. They have a glycosamino-glycans coating, and the outer membrane covers the three flagella that provide motility. T. pertenue requires a pH in the range of 7.2 to 7.4 and grow at temperatures in the range of 30 to 37 degrees C. These organisms cannot be cultivated on artificial media, but can only be maintained for a few days on Nelson's medium. This contains crystallized serum albumin, dissolved CO2, either cystein or glutathione, pyruvic acid, and a serum ultrafiltrate factor.
Unlike its very close relative, Treponema pallidum, this bacterium is not passed through sexual contact. It has been shown to be spread by direct contact to an open lesion, but it cannot pass through intact epithelium. However, a cut or abrasion only has to be microscopic for it to act as a portal for the disease. Some studies have suggested that flies may be a possible carrier, but there is not enough evidence to support this theory. As described in the introduction, Penicillin is the treatment of choice if a person is infected.
REFERENCES
Dubos, Rene J. and Hirsch, James G. Bacterial and Mycotic Infections of Man, Fourth Edition.
J.B. Lippincott Company, Philadelphia: 1965.
Web page - http://www.cehs.siu.edu/fix/medmicro/trepo.htm
Web page - http://ponderosa-pine.uoregon.edu/students/Elder/cause.html
*Disclaimer - This report was written by a student participaring in a microbiology course at the Missouri University of Science and Technology. The accuracy of the contents of this report is not guaranteed and it is recommended that you seek additional sources of information to verify the contents.
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