我想問，Fifth Disease 是什麼意思？

Fifth disease
Fifth disease is also referred to as erythema infectiosum (meaning infectious redness) and as slapped cheek syndrome, slap face or slapped face.The name "fifth disease" is mainly historical: it is the fifth in the list of diseases causing childhood exanthemata (rashes). In 1975, its cause was discovered to be Parvovirus B19.

圖片參考：http://upload.wikimedia.org/wikipedia/en/9/9c/Slapped_cheek.png

Toddler with "slapped cheek" characteristic of the fifth disease.

Symptoms

The bright red cheeks are a defining symptom of the infection in children (hence the name "slapped cheek disease"), but the rash will not extend over the bridge of the nose or around the mouth. In addition to the red cheeks, children often develop a red, lacy rash on the rest of the body, with the upper arms and legs being the most common locations. Patients are usually no longer infectious once the characteristic rash of this disease has appeared.

Teenagers and adults may present with a self-limited arthritis. Babies can turn purple.
The disease is usually mild, but it does have the ability to cause some serious problems: it is associated with spontaneous abortion in pregnant women, and with transient aplastic crisis in persons with chronic hemolytic anemia. Primary infection in the first trimester has been linked to hydrops fetalis. The rash can last a couple of weeks (some cases lasting for several months) and may itch.


2007-04-01 00:37:07 補充：
細小病毒B19 (Parvovirus B19) 引起第五病(Fifth Disease)，病徵包括面都出現似被掌摑後的紅印，因而有「掌摑面」病(Slapped Face Disease) 的別名。患者身體其他部分也可能出現淡紅色的疹，部份會有關節腫痛，但大部份不會出現發燒。病毒由飛沫傳播，潛服期長達2 至3 周，患者主要在潛服期把病毒傳人，但當面部紅印出現後便不再有傳染性。一般患者在短期內自動痊癒，但孕婦感染，可導致胎兒貧血，甚至流產。先天性貧血如地中海貪血患者，感染細小病毒B19 可引致貧血急性惡化。沒有針對性藥物，也沒有預防疫苗，預防只能靠提升個人衛生。

第五種疾病