The mosquito-borne Zika has not been thought as a killer virus and was known for causing almost no symptoms in infected individuals. Those who do show symptoms often only suffer from rashes, headaches, muscle aches, and sometime conjunctivitis at worst.

As the virus continues to infect thousands of people, however, symptoms that were never seen before such as brain defects in children born to infected mothers have been noted. Some of the pregnant women who get the virus also experience miscarriages and having babies who died soon after birth.

As more cases of the disease emerge, it appears that Zika can be fatal even among adults. In Colombia, for instance, three adults have died of Zika-linked Guillain-Barre syndrome in February. The autoimmune disease affects the nerves of the body causing muscle weakness and sometimes even paralysis.

Now, the U.S. has reported another case of Zika death. The U.S. Centers for Disease Control and Prevention (CDC) and the Puerto Rico Department of Health revealed on Friday that a 70-year-old Puerto Rican man died because of complications from Zika virus in February.

The patient contracted the virus and received treatment for symptoms but he returned to the hospital a few days after recovery with symptoms of a bleeding disorder. He was diagnosed with immune thrombocytopenic purpura (ITP), a disorder marked by the immune system attacking the platelets that play a role in blood clotting.

"As an elderly man, this individual did have some underlying health conditions, but they were not life-threatening and not likely to have led to his death," said CDC epidemiologist Tyler Sharp.

Sharp said that this is the ninth reported case of bleeding linked with Zika. The five cases in French Polynesia and Suriname survived but three in Colombia did not.

The incident showed that the Zika virus is not as harmless as it was once thought. The symptoms and complications that may arise can be particularly dangerous for certain individuals including the elderly and those who already have existing conditions.

"Although Zika virus-associated deaths are rare, the first identified death in Puerto Rico highlights the possibility of severe cases, as well as the need for continued outreach to raise health care providers' awareness of complications that might lead to severe disease or death," the CDC said.