Mononucleosis is an infectious disease of humans in which the blood and tissues contain mononuclear leukocytes (white blood cells 
with only one nucleus), either monocytes or lymphocytes. An infectious disease is a disease that can give you an infection, can be transmitted by infection without actual contact, or can be caused by a microorganism. All species of animals are afflicted with infections caused by a wide variety of organisms, from submicroscopic viruses to wormlike parasites. When a person has an infectious disease like mono the organism gains access to the patient’s body, survives, and then multiples. Next, the patient gets the symptoms. Then the patient may die or recover spontaneously, or the infection may respond to specific therapy. Often there is immunity. Infectious diseases have strongly influenced the course of history on Earth. The organisms responsible for human infections are viruses. Viruses are simple life forms consisting of nucleic acid, encoding genetic information, and surface components of protein that enable them to enter cells. Viruses are unable to multiple outside of cells. Mono is found in the DNA in the body. Another name for mononucleosis is glandular fever because of the fever and swelling of the lymph nodes throughout the body. What causes mononucleosis is the Epstein-Barr virus (EBV), which is like herpes. The herpes virus also causes some cases of mono and other diseases. Mono usually occurs in adults 15 to 30 years old, but is known to appear at any age.
Mono symptoms include fever, chills, fatigue, malaise, sore throat, head-aches, swelling of the lymph nodes (noticeable in the neck), and skin rashes. Liver inflammation may occur. Also, swelling of the upper eyelids is a common symptom. In some cases blood may be found in the urine. The throat is often red; a membrane, white to dark gray in color and resembling that of diphtheria, may be present. In many cases there is a petechial rash on the soft palate. Mono is mostly transmitted by oral contact with exchange of saliva, which is why it is sometimes known as the “kissing disease.” Sharing a cup is another way to get mono. It is not highly contagious. The incubation period is thought to be about 30 to 40 days. In about two/thirds of the patients the spleen is enlarged. The illness is mild to moderate, death is rare, but in some cases a patient may die of rupturing the spleen. A rash consisting of small hemorrhages or resembling measles or scarlet fever sometimes appears. Also, pneumonia occurs in about 2 percent of the infected patients. Although, involvement of the liver occurs almost in all the patients, but severe disease of the liver is rare. Encephalitis, 
meningitis, or peripheral neuritis occurs uncommonly. Death has followed encephalitis. While having mono, the heart is rarely affected.
During the illness antibodies develop. One way to detect this is by the Paul Bunnell test. The diagnosis is made by studying the blood. A sample of the serum (clear liquid) of the patient’s blood is mixed with sheep’s blood. If the patient has the disease, the sheep’s blood cells will stick together. There is no treatment, but bed rest is suggested depending on the seriousness. Medical care is for relief of symptoms and prevention of secondary infections. Mono usually lasts for about a week or two or sometimes it may persist for several weeks, especially when the liver or nervous system is affected. A relapse occurs uncommonly, and second attacks are probably very rare. Recovery may take several months. The disease known as Chronic Fatigue Syndrome, or “yuppie disease “resembles mono. For a while the Chronic Fatigue Syndrome was suspected of also being caused by EBV, but this theory has been discounted. Still no cure or therapy has been found to help us with the infectious disease called mononucleosis.
