Measles is a highly contagious viral disease that can have devastating effects on the human body, especially in children and those with weakened immune systems. Caused by the measles virus, it spreads through respiratory droplets and remains one of the leading causes of vaccine-preventable deaths worldwide, despite the availability of a highly effective vaccine. Understanding what measles does to your body is critical in appreciating the seriousness of the disease and the importance of immunization.

Once the measles virus enters the body, usually through the nose or mouth, it begins to replicate in the back of the throat, lungs, and lymphatic system. The incubation period lasts about 10 to 14 days, during which the infected person typically has no symptoms but is already becoming contagious. As the virus spreads, it begins to suppress the immune system and causes symptoms to appear.

The first signs of measles resemble those of a common cold: high fever, cough, runny nose, and red, watery eyes. One of the telltale signs of measles is the appearance of Koplik spots, which are tiny white lesions found inside the mouth, usually on the inner lining of the cheek. These appear a day or two before the characteristic rash develops.

A few days after the initial symptoms, a red, blotchy rash begins to form, starting on the face and gradually spreading downward to the rest of the body. This rash usually lasts for about five to six days. During this period, the fever can become extremely high—sometimes reaching over 104°F (40°C). The rash and fever, while uncomfortable, are just surface-level signs of the damage measles is doing internally.

One of the most dangerous effects of measles is how it suppresses the immune system. The virus attacks and destroys white blood cells, which are essential for fighting infections. This immunosuppressive effect can last for weeks or even months after the visible symptoms have resolved, leaving individuals vulnerable to other diseases. In fact, studies have shown that measles can erase the body’s "immune memory," making people susceptible again to illnesses they were previously immune to.

Measles can also lead to serious complications, especially in young children, pregnant women, and immunocompromised individuals. These complications include pneumonia, severe diarrhea, ear infections, and encephalitis—a dangerous inflammation of the brain that can cause permanent brain damage or death. In developing countries, where nutrition and access to healthcare are limited, measles can be particularly deadly. According to the World Health Organization, measles caused over 136,000 deaths globally in 2022, most of them among children under the age of five.

Long-term effects of measles can be equally concerning. A rare but fatal condition called subacute sclerosing panencephalitis (SSPE) can develop several years after a person has recovered from measles. SSPE is a progressive brain disorder caused by a persistent infection with the measles virus and leads to cognitive decline, seizures, and eventually death. Though rare, this condition highlights just how dangerous the measles virus can be long after the initial infection.

The good news is that measles is preventable. The MMR vaccine, which protects against measles, mumps, and rubella, is safe and more than 97% effective after two doses. Widespread vaccination not only protects individuals but also contributes to herd immunity, reducing the chance of outbreaks and protecting those who cannot be vaccinated for medical reasons.

In conclusion, measles is not just a simple childhood illness. It is a serious and sometimes fatal disease that can cause long-lasting damage to the immune system and other organs. Understanding what measles does to the body should serve as a strong reminder of the importance of vaccination and public health efforts to prevent its spread.