The first time hearing the term “yaws,” most people immediately think of the classic 1975 Spielberg film, Jaws. No, yaws has nothing to do with the 25 foot great white shark terrorizing a New England beach town. In fact, yaws might actually be more dangerous. Yaws is one of the many neglected tropical diseases that affect some of the world’s poorest communities. The bacterial infection mainly affects the skin along with bones and cartilage. Possibly having the most interesting name amongst the NTDs, the origin of the title is not entirely known. Some believe it came from the Caribbean Indian language, where “yaya” means “a sore.” Another possibility is from an old African language in which “yaw” might have meant “a berry, ” a potential reference to the lesions that form from the disease. To learn more about the threatening infection, one must examine its epidemiological triangle. An epidemiological triangle includes the three necessary components for a disease to thrive: the agent, the host, and the environment. Eliminate one of these and the disease will most likely be eradicated.
First, the agent, or the actual disease itself. Yaws is caused by the bacterium treponema pertenue (pictured below). It is closely related to the bacterium that causes syphilis (treponema pallidum). Treponema is a type of spirochete, a double membrane bacteria with long coiled cells.
The bacteria is transmitted from skin to skin contact. Since it cannot penetrate human skin, it must enter through a scrape or cut. Unlike its close relative treponema pallidum, yaws bacteria cannot be passed on during a sexual encounter. About 2-8 weeks after infection a bump arises at point of entrance. This usually painless bump is called the “mother yaw.” Smaller bumps form weeks later and are called “daughter yaws.”
Next, the host, or the human carrying the disease. The overwhelming majority of victims of yaws are below the age of 15. Yaws mainly affects the skin, as noticeable and gross bumps protrude from the host’s flesh. Most patients also experience either joint or bone pain along with a fever. Early detection of the disease is absolutely vital. A positive test of yaws comes from a doctor’s examination of an infected skin sample under a microscope. As of now, there is no blood test for yaws.
In terms of treatment, there are actually two good options of antibiotics to combat yaws. The World Health Organization recommends an oral dose of azithromycin. Azithromycin is an inexpensive antibiotic used to treat various infections, and it is easy to take. The alternative option would be a benzathine penicillin injection. Similar to azithromycin, benzathine is used to treat a range of infections. However, a study funded by the International SOS showed that azithromycin and benzathine are equally effective. One can conclude that azithromycin is the better choice because it is cheaper and can be taken without medical assistance. Both of these treatments can treat yaws if the disease is detected early.
The final corner of the epidemiological triangle is the environment. Yaws has been a problem in tropical regions all around the globe. This includes areas near the equator in Africa, Asia, South America, Central America, and Pacific Islands. The infection thrives in communities with high poverty rates, where lack of proper treatment allows the disease to spread easily. Areas with overcrowding and poor hygiene also pose as a great environment for yaws to claim victims. The most basic way to prevent yaws is to maintain good hygiene. Wash your hands often, use hand sanitizer, bathe frequently, and tend to open wounds. Sadly, people in impoverished communities do not have good access to these amenities.
Doctors and biologists around the world are doing their best to minimize yaws outbreaks, and it seems to be working. In fact, the World Health Organization predicted that yaws could be eradicated by as early as 2020 if the necessary steps are taken. A great example of medical success occurred in India in 2016. Medical professionals educated the communities and provided proper screening and treatment to the country until India was declared yaws-free in May of 2016. The India project helped the movement gain momentum. It will hopefully lead to more success in the future.