Measles is an acute infectious disease that is caused by a virus that penetrates the body through the mucous membranes of the mouth, nose, and eyes. A person may get measles only once during the entire life because after the disease an organism produces strong immunity against it.
Five main symptoms of measles are as follows.
Fever. The disease begins with a sharp rise of temperature to 38-40 degrees. Virus particles enter the blood flow and interact with lymphocytes. Lymphocytes release substances that serve as a signal to the hypothalamus (part of the brain) to increase a body temperature. Fever is a mechanism that helps to create unfavorable conditions for the virus reproduction and accelerates the production of antibodies that can overcome the disease.
Rash. Skin rash is manifested by bright pink formations of irregular shape. They have a flat top and slightly raise above the skin surface. Separate elements gradually grow and merge together, covering large areas of the face. Rash also appears in the mouth in a form of red spots of a pinhead size. It usually occurs in those places where intense viral replication caused dilation of capillaries. After another 2-3 days, entire oral mucosa gets inflamed and acquires red color, so the spots become invisible. Consequent stages are considered a characteristic feature of measles. First of all, a rash appears on the forehead, face, neck and behind the ears. It spreads to the torso and arms on the second day and to the feet and fingers on the third day. The rash disappears exactly in the same order it started. It often happens that while new rash emerges on the legs, the papules on the face start darkening.
A rhinitis and dry cough. The virus damages the mucosa of the upper respiratory tract causing its inflammation. The organism produces a special kind of protein to combat them and plenty of liquid is released from the damaged capillaries. In this case, the nasal discharge is transparent but if the leukocytes start fighting the virus the color changes to yellow-green. A cough appears as a consequence of the larynx swelling. If the inflammation spreads to the vocal cords, the voice may disappear.
Conjunctivitis. Conjunctivitis is accompanied by photophobia and purulent discharge. Virus proliferates on the back surface of the eyelids. This leads to their swelling and inflammation. Eye blood vessels become visible as well as small hemorrhages that occur due to the destruction of the capillaries. Photophobia results from the inflammation of the eye membranes. Sometimes it causes frequent involuntary blinking.
Inflammation of the cervical lymph nodes. Lymph nodes filter the blood purifying it from various viruses. They actively produce lymphocytes to fight measles infection. Increased functioning of the lymph nodes and proliferation of viruses inside it leads to the increase in its shape and further inflammation.