MIAMI, United States (AFP) – The first death related to the mosquito-borne Zika virus infection on US soil was reported Friday in the US territory of Puerto Rico, health officials said.

“The patient died of complications related to severe thrombocytopenia,” a condition related to a low number of platelets in the blood, the US Centers for Disease Control and Prevention said.

“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.”

Officials provided no further details about the patient who died.

The CDC has warned of a potential explosion of Zika cases in Puerto Rico, possibly reaching into the hundreds of thousands.

The virus is known to cause the brain defect microcephaly, and is blamed for a recent surge in cases of malformed babies in Brazil.

The health authorities urged people in Puerto Rico to “continue to employ mosquito bite avoidance behaviors, including using mosquito repellents, wearing long-sleeved shirts and pants, and ensuring homes are properly enclosed.”

Since Zika is also known to be transmitted by sexual contact, partners of pregnant women are being urged to use condoms or avoid sex until the baby is born.

Puerto Rico reported its first Zika case — known as the index patient — in November.

“In December 2015, Puerto Rico became the first US jurisdiction to report local transmission of Zika virus, with the index patient reporting symptom onset on November 23, 2015,” the CDC said.

The CDC investigated a total of 6,157 suspected Zika cases in Puerto Rico between November 1, 2015 and April 14, 2016.

Scientists confirmed that 683 (11 per cent) “had laboratory evidence of current or recent Zika virus infection,” it said.

The most common symptoms were rashes, joint and muscle pain, headaches and fever.

Sixty-five pregnant women tested positive for Zika.

A total of 17 patients required hospitalisation, including five with suspected cases of Guillain-Barre syndrome, a rare disorder in which the immune system attacks the nerves.