A baby born with brain defects caused by the mosquito-borne Zika virus has died in Texas, marking the southern state's first Zika-related death, officials said Tuesday.

Meanwhile, the number of locally transmitted cases of Zika in the Miami area jumped to 21, prompting both Florida's Republican governor and Democratic presidential candidate Hillary Clinton to urge the nation's lawmakers to re-convene from their summer break and agree on a funding bill for the outbreak.

"This is not only an issue affecting us here in Florida, this is a national issue," said governor Rick Scott, describing the baby's death in Texas as "a heartbreaking tragedy in our country."

The mother had become infected with Zika while traveling in Latin America, and gave birth to the baby in Harris County near Houston, according to the state health department.

"The baby passed away shortly after birth and is the first Zika-related death reported in Texas," said a statement.

"Recent test results confirmed the baby's condition and link to Zika. The mother and baby are classified as travel-related cases, and there is no additional associated risk in Texas," it said.

In June, an elderly man in Utah became the first person to die of Zika in the mainland United States.

The US Centers for Disease Control and Prevention is only reporting limited information about Zika cases to protect patient privacy.

A CDC spokesman told AFP by email that the agency is aware of the news from Texas but offered no further details.

The CDC says 15 infants have been born in the United States with Zika-related defects, and six pregnancy losses are associated with Zika infection.

Microcephaly risk

Zika often causes no symptoms, but is particularly dangerous for pregnant women because it can lead to the birth defect microcephaly, in which infants are born with unusually small heads and deformed brains.

Texas has reported 97 cases of Zika, including two infants with microcephaly.

All these cases "are related to travel abroad to areas with active Zika transmission," said the statement.

Florida is so far the only US state to report that mosquitoes are actively transmitting the virus.

A total of 21 Zika cases in the Miami area are believed to be linked to mosquitoes carrying the virus in the Wynwood neighborhood.

Another 369 cases in Florida were brought in by people who were infected while traveling outside the United States.

Florida's governor said money to respond to Zika is running short, and the state needs 10,000 more Zika prevention kits.

President Barack Obama asked lawmakers to authorize $1.9 billion for Zika back in February. But Republicans in Washington disagreed, saying the money should be moved from funds previously set aside for Ebola.

Then, lawmakers went on summer recess without approving a bill.

"The federal government must stop playing politics and Congress needs to immediately come back to session to resolve this," Scott said.

Hillary Clinton, who was campaigning in Florida on Tuesday, also urged Congress to come back to work.

"I'm asking the Republican leaders in the House and the Senate to call congress back in to session immediately and to pass the bipartisan funding bill that the Senate passed," she said.

"Unfortunately, a different bill was passed in the House and no agreement could be reached before they went out on recess," she added.

"So pass the bipartisan bill from the Senate or come up with a new compromise that does the same."