Discoid meniscus is a rare human anatomic variant that usually affects the lateral meniscus of the knee. Usually a person with this anomaly has no complaints; however, it may present as pain, swelling, or a snapping sound heard from the affected knee. Strong suggestive findings on magnetic resonance imaging includes a thickened meniscal body seen on more than two contiguous sagittal slices. Description
The Watanabe classification of discoid lateral meniscus is: (A) Incomplete, (B) Complete, and C) Wrisberg-ligament variant   Normally, the meniscus is a thin crescent-shaped piece of cartilage that lies between the weight bearing joint surfaces of the femur and the tibia. It is attached to the lining of the knee joint along its periphery and serves to absorb about a third of the impact load that the joint cartilage surface sees and also provides some degree of stabilization for the knee. There are two menisci in the knee joint, with one on the outside (away from midline) being the lateral meniscus and the inner one (towards midline) the medial meniscus. A discoid meniscus is a congenital anomaly of the knee found in 3% of the population (up to 15% in Asia). It typically affects the lateral meniscus and may be found bilaterally (20%). Instead of the narrow crescent shape, as seen in a normal meniscus above, a discoid meniscus is thickened, and has a fuller crescent shape. In addition, a discoid meniscus does not taper as much towards the center of the joint and is shaped like a disc.
Murine typhus, also known as endemic typhus or flea-borne typhus, is a form of typhus transmitted by fleas (Xenopsylla cheopis), usually on rats, in contrast to epidemic typhus which is usually transmitted by lice. Murine typhus is an under-recognized entity, as it is often confused with viral illnesses. Most people who are infected do not realize that they have been bitten by fleas. Historically the term "hunger-typhus" was used  in accounts by British POWs in Germany at the end of World War I when they described conditions in Germany. Signs and symptoms
Symptoms of endemic typhus include headache, fever, muscle pain, joint pain, nausea and vomiting. 40–50% of patients will develop a discrete rash six days after the onset of signs. Up to 45% will develop neurological signs such as confusion, stupor, seizures or imbalance. Symptoms may resemble those of measles, rubella, or possibly Rocky Mountain spotted fever. These symptoms are likely caused by a vasculitis caused by the rickettsia. Causes
It is caused by the bacterium Rickettsia typhi, and is transmitted by the fleas that infest rats. While rat fleas are the most common vectors, cat fleas and mouse fleas are less common modes of transmission. These fleas are not affected by the infection. Human infection occurs because of flea-fecal contamination of the bites on human skin. Rats, cats, and opossums maintain the rickettsia colonization by providing it with a host for its entire life cycle.