Local NBC affiliate WBIR in Knoxville, Tennessee is reporting tonight that the Knox County Health Department is investigating an unusually large spike in confirmed Hepatitis A illnesses in the area.

“In the past week we’ve received reports of 7 cases, which is really a significant increase,” Dr. Martha Buchanan, of Knox County’s Health Department said.

The virus is relatively rare in Knox County. So, when they got that many calls from doctors in the area, the health department started investigating and called local hospitals to let them know of the outbreak.

So far no confirmed source has emerged, but the investigation is ongoing.  Some notable recent past Hepatitis A outbreaks have involved various food service establishments, including:

Hepatitis A is a particularly nasty virus, with symptoms taking between 15 and 50 days to appear after exposure.  The symptoms typically include include muscle aches, headache, anorexia (loss of appetite), abdominal discomfort, fever, and malaise.  After a few days of these initial symptoms, jaundice appears.  Jaundice is a yellowing of the skin, eyes and mucous membranes that occurs because bile flows poorly through the liver and backs up into the blood.  The urine will also turn dark with bile and the stool light or clay-colored from lack of bile. When jaundice sets in, the initial systemic manifestations (such as fever and headache) typically begin to subside.