11. Meningitis
Meningitis refers to inflammation of the meninges, or the membranes that cover the brain and spinal cord. This infectious disease can be caused by a number of things, including fungi, viruses and bacteria.
Bacterial and viral meningitis are the most common types and can be spread from person to person. Whereas bacterial meningitis is often spread through kissing, viral meningitis is typically spread when someone comes into contact with the feces of an infected person (i.e. when changing a diaper or when a person doesn’t wash his or her hands properly after using the toilet), according to the CDC.PLAY SOUND
Some people get meningitis after suffering a head injury, having brain surgery or having certain kinds of cancer. This type of meningitis is not contagious, nor is fungal meningitis, which was responsible for a meningitis outbreak in the U.S. in 2012.
Some people with meningitis develop meningococcal disease, which is caused by the bacteria Neisseria meningitides. The disease causes flu-like symptoms, as well as nausea, vomiting, increased sensitivity to light and an abnormal or confused mental state, according to the CDC.
12. Syphilis
Syphilis is a sexually transmitted disease that is easily treated but can lead to serious complications if neglected. In the first stage of the disease, sores may appear on a person’s genitals or anus. Usually these sores are small and painless, and they heal on their own, leading many people to simply overlook them or confuse them with ingrown hairs or blemishes.
The second stage of the disease is more noticeable and usually begins with a rash on one or more parts of the body. Sometimes these rashes can be very faint, and since they don’t itch, people infected with the disease might not know they have it. Others may develop more severe symptoms such as fever, swollen lymph glands and muscle aches.
If syphilis is left untreated throughout the first and second stages of the illness, it can cause much more severe problems later on, according to the CDC. Some people don’t develop symptoms of the late stage of syphilis until 10 to 30 years after they contract the disease. Late-stage symptoms include difficulty coordinating muscle movements, paralysis, numbness, blindness and dementia. The disease can also damage internal organs, which may result in death.