It is always fascinating and interesting to learn the origin of the names of certain diseases that have become part of our routine daily vocabulary. We use these names each and every day without giving much thought as to why a certain disease is called such. We just take it for granted. This came to light when I was making teaching rounds with the residents and medical students. We were discussing common childhood illnesses and the question came up as to why chicken pox was called "chicken pox", and how Fifth disease got its name.
This prompted me to go to my file of articles that I had amassed over the years. Sure enough, I found an article from 1980 that discussed the genesis of the name chicken pox. In this article it says that the term chicken pox first appeared in the medical literature in 1694. Richard Morton, an English physician, described what he believed to be a mild form of smallpox in his writings The Science of Fevers and Their Characteristics, Second Part: or, a Treatise Regarding General Inflammatory Fevers. In his paper he refers to this mild form of smallpox as "...this type are called in our vernacular The Chicken Pocks."
In 1730, in a paper on diseases that caused rashes, Fuller speculated that chicken pox was called such because the lesions gave the appearance one would expect to see if a child had been pecked with the bills of chickens.
In the years that followed, chicken pox appeared throughout the medical literature, and it was shown that smallpox and chicken pox were two entirely different diseases. Yet, there was no clear understanding as to how chicken pox actually got its name. This seems to have been cleared up in 1886 in a book written by C.H. Fagge entitled The Principles and Practices of Medicine. In this book, he states that in all probability, the allusion with the name chicken pox refers to the chicken pea (Cicer arietinum), and most modern authorities are in agreement.
The chick pea exists throughout the world and is actually the world's third largest seed crop. In India it is known as gram or chana. In Arab countries it is referred to as hummus. In Israel it is chimtza; in Spain it is the garbanzo and in Germany it is kichererbse. The typical chick pea seed is 7-10 mm long and 5-7 mm wide, while the typical chicken pox vesicle is 3-4 mm wide. The surface texture and cream color of the chick pea makes it look very much like the vesicle of chicken pox. It is this close resemblance of the vesicles to the chick pea that gave chicken pox its name.
The other disease that came up during rounds was that of Fifth disease. This is a common childhood infection that is benign and self-limiting. It starts with a "slapped face" appearance of the cheeks whereby the cheeks are bright red. This resolves fairly quickly and is replaced by a lacy or reticular rash on the trunk and proximal extremities. This lacy rash becomes more florid and intense with heat, such as a hot bath or running around on a hot day. This rash gradually works its way down the extremities and disappears after a couple of weeks. Children with Fifth disease are usually not very ill, and only around 15-20 percent have any fever or any symptoms.
This is an age-old illness that is known as erythema infectiosum. It has been well-described in the medical literature for generations. At the turn of the last century the medical community organized or classified the childhood exanthems--illnesses that caused skin rashes. There was rubella, measles, scarlet fever, and Filatov-Dukes disease (atypical scarlet fever). Erythema infectiosum was the next one classified, or the "fifth" one named. Hence it acquired the name Fifth disease, and is still known by that name.
In the 1980's researchers discovered the parvoviruses, and determined that Fifth disease was caused by Human parvovirus B-19. When most people heard this they seemed shocked and asked, "I thought that dogs got parvovirus, not people!" While it is true that dogs do get parvovirus, B-19 is a virus that only affects humans and is the cause of Fifth disease.
The genesis of names over the centuries is quite interesting. Whether or not chicken pox truly was named such because the vesicles resembled the chick pea, or garbanzo bean, will probably never be determined without question. But it makes for interesting discussions. I must say, after reading that article, whenever I have a salad with garbanzo beans in it, it never quite tastes the same.
After over a century of knowing about Fifth disease as a common childhood illness, it's humorous to think that it could have easily been dubbed Third disease of Fourth disease.