Preserved samples of mosquitoes collected from the Zika Forest in Entebbe, south of Uganda's capital Kampala are seen on a tray during research work by scientists from the Uganda Virus Research Institute, March 2, 2016. REUTERS/James Akena

(Reuters) - Quest Diagnostics Inc said it has received emergency authorization from the U.S. Food and Drug Administration to sell the first commercially developed diagnostic test for Zika in the United States, a step that may help expand testing capacity and speed diagnosis of the virus.

Previously, the only Zika blood tests that had Emergency Use Authorization, or EUA, were available from the U.S. Centers for Disease Control and Prevention and were only to be used in qualified laboratories designated by the CDC.

Quest, in its announcement on Thursday, said it plans to make the new test broadly available to doctors for patient testing, including in Puerto Rico, by early next week.

Currently, the only laboratory that will use the new Zika test is at Quest’s reference laboratory in San Juan Capistrano, California, where the test was developed and validated. But the Emergency Use Authorization may allow for testing at other qualified laboratories, including one in Puerto Rico, Quest said in a statement.

Quest’s molecular test for Zika can only detect the virus when it is still present in the blood. A negative test does not completely rule out Zika infection. Further serological tests that look for antibodies made in response to the virus can help confirm infection. Quest said it is exploring options to make serological tests for Zika available as well.

The FDA’s authorization is for emergency use, and does not constitute FDA approval.

The World Health Organization (WHO) declared the Zika outbreak an international health emergency on Feb. 1. The outbreak is affecting large parts of Latin America and the Caribbean, with Brazil the hardest hit so far.

U.S. health officials have concluded that Zika infections in pregnant women can cause microcephaly, a birth defect marked by small head size that can lead to severe developmental problems in babies.

The WHO has said there is strong scientific consensus that Zika can also cause Guillain-Barre, a rare neurological syndrome that causes temporary paralysis in adults. The connection between Zika and microcephaly first came to light last fall in Brazil, which has now confirmed more than 1,100 cases of microcephaly that it considers to be related to Zika infections in the mothers.