A brain-eating amoeba is causing terror in Pakistan.

At least ten people have been fatally affected in the southern city of Karachi in Pakistan, according to the World Health Organization.

On Tuesday, the WHO confirmed that the amoeba arrived in the city of 18 million people in May this year.

An official for the WHO said the culprit was Naegleria fowleri, a deadly amoeba that enters the human body through the nasal passage and travels to the brain. Most cases are usually attributed to people swimming or coming in contact with infected water. The amoeba is a very effective killer with a death rate over 98 percent.  

Dr. Musa Khan, head of the WHO's Disease Early Warning System in Pakistan, stated: "People should avoid getting water too deep into their nostrils and make sure their water supply is properly treated. Those with symptoms should seek help immediately."

There may be more incidents that have not been reported as many people are not aware of the amoeba.

Those that are affected show mild initial symptoms such as stomach pain, fever and headaches. It takes around a week for the infection to kill.

Many of Pakistan's hospitals are crowded, making tracking the disease even more difficult.

While health officials are planning to try and spread awareness of Naegleria fowleri, Dr. Khan isn't too worried with the latest fatalities.

"There is no need to panic over these deaths," said Dr. Khan. "There is a remote chance for the spread of this deadly disease."

According to the WHO, testing is being conducted on water sources that may be the cause of the recent infections.

The city of Karachi had a previous outbreak of the disease in 2006, but the recent cases are the first for a reappearance of the brain-eating amoeba.