Chembio Diagnostics Inc. on Thursday reported that its loss narrowed in the January-March period compared with a year earlier on higher sales of the company’s HIV tests in the United States.

The Medford-based developer of rapid tests for HIV, and for malaria, Ebola, Zika and other diseases marked by fever said it lost $304,000 in the first quarter compared with a loss of $647,000 in the first three months of 2015.

Sales climbed to $6.6 million in the quarter, a gain of 6 percent, year over year.

CEO John J. Sperzel said Chembio’s financial performance benefited from an increase of 78 percent, or $1 million, in domestic sales of point-of-care tests for HIV.

“We are pleased with the demand for our HIV products in the U.S., and, as previously noted, effective June 1, 2016 we will begin selling the Sure Check HIV 1/2 assay in the U.S. through our existing sales force and distribution channels,” he said in a statement.

The Sure Check tests have been sold by a third party in the past after being manufactured by Chembio.

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Sperzel also said the company continues to develop rapid tests for diseases involving fevers, most notably Zika. It is seeking regulatory approval to introduce a Zika test in Brazil, where many are affected by the disease.

He said Chembio hopes its tests will “allow health care workers to change current testing paradigms and contain the spread of life-threatening diseases.”

Chembio shares rose 19 cents, or 2.7 percent, to close at $7.47 Thursday on the Nasdaq Stock Market.