First Zika death in U.S. lived in Puerto Rico

Zika has claimed its first American life — a Puerto Rico resident who developed a severe loss of platelets, the cells that control bleeding by helping blood to clot.

Puerto Rico has been hit harder than anywhere else in the U.S.

According to a report published online Thursday, the Puerto Rico health department and the Centers for Disease Control and Prevention tested 6,157 blood samples for Zika between Nov. 1 and April 14. Blood tests found that 683 had current or past Zika infections, including 65 pregnant women. Pregnant women are considered to be at highest risk from the virus, which can cause catastrophic birth defects in their infants.

Zika infections are usually mild and deaths are rare, according to the CDC. About 20% of patients develop symptoms, such as a fever, itchy rash, pink eye and joint pain. The rest of patients have no symptoms at all.

Among patients who had symptoms in the CDC report, 74% had a rash, 68% had muscle aches, 63% had headaches, 63% ahd fever and 63% ahd joint pain. Seventeen patients were hospitalized, including five with suspected Guillain-Barré syndrome, a form of paralysis that occurs when the immune system attacks the body's nerve cells.

One Zika patient in the continental U.S. has developed Guillain-Barre, along with five in U.S. territories, according to the CDC.

Guillain-Barre deaths tend to be more common in places without access to intensive care units, which can keep patients alive until they recover.

Other Zika patients have developed inflammation of the membranes around the brain.

Colombia and Brazil have both reported deaths from Zika. Colombia has released details on five deaths.

Zika outbreak in Puerto Rico grows, endangers pregnant women

One of the fatalities was a girl with had sickle cell disease. Others deaths occurred in a 2-year-old girl, a 30-year-old woman, a 61-year-old man and a 72-year-old woman. The two older patients had underlying medical conditions. The two younger patients had acute leukemia, which was detected only after death. All of the patients had fever. Three were dehydrated and three had very low platelet levels.

"As the number of infected grows, complications such as death that are rare become measurable," said Amesh Adalja, a senior associate the Center for Health Security at the University of Pittsburgh Medical Center. "We can expect to see more (deaths) until the spread of this virus is halted."

Deaths are more common in other viral diseases, such as dengue and chikunguyna, which are transmitted by the same mosquito species that transmits Zika, the Aedes aegypti, Adalja said.

There are four types of dengue virus. Patients often survive a first infection with dengue with few serious problems. Patients may suffer serious complications, however, if they develop a second dengue infection.

Some scientists have speculated that some of Zika might also be more dangerous in people who have had dengue. Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston, said he hopes researchers find out whether the man who died had suffered from dengue.

Although 426 travelers have been diagnosed with Zika in the continental U.S., the virus is not yet spreading among mosquitoes here, and there have not been any homegrown cases, according to the CDC.

The Obama administration this week announced that it will provide $5 million to Puerto Rican health clinics.