Barack Obama once again called for almost $1.9bn (£1.4bn) in emergency funding to fight the Zika virus, rejecting a Republican proposal to reshuffle remaining Ebola funds to fight the epidemic threatening Latin South America.

In a letter to House Republicans, Office of Management and Budget head Shaun Donovan said Ebola is "still a threat" and that federal health and security officials still have plans to combat the virus with the remaining funds.

According to The Hill, Donovan warned that moving Ebola funds to fight Zika would "put this nation at risk" for another public health crisis. "Despite progress, our work to combat Ebola and establish capacity to prevent future public health crises is not complete," Donovan wrote to the House Appropriations Committee. He noted that the funds allocated to fight Ebola were "always intended to be spent over multiple years."

The president asked Republicans the administration wanted $1.8bn in additional funds to fight off the mosquito-borne Zika virus. However, House Republicans rejected Obama's request because there was still over $1bn leftover from the country's fight against Ebola.

"Before the submission of an emergency supplemental request, it seems incumbent upon the Administration as well as Congress to pursue the use of unobligated funds, including unobligated Ebola funds, which are substantial, to meet the needs of responding to the Zika outbreak," said House Appropriations Committee Chairman Harold Rogers, a Republican from Kentucky.

In response, Donovan argued that those funds were critical in building up the country's public health infrastructure and preventing the spread of other potentially deadly epidemics around the world.

The letter arrived the same day the White House submitted its official emergency funding request for $1.9bn. The Hill reported that around $1.5bn of the requested funds would be given to the Department of Health and Human Services (HHS). Those funds would then be distributed to the Centers for Disease Control and Prevention (CDC), the Food and Drug Administration (FDA), the National Institutes of Health (NIH) and the Centers for Medicare and Medicaid Services (CMS).

A designated amount of $300m would help "diagnose, prevent, and treat" the virus, while an addition $130m would be devoted to creating vaccines. The budget proposal calls for $335m in new funding for the US Agency for International Development (USAID) and $41m for the State Department. The request also asked for the power to access the State Department's Ebola funding if necessary to fight against the Zika virus. However, it would allow the State Department to be reimbursed for any funds spent on the fight against Zika.

Zika has spread to at least 32 countries and territories throughout the Americas and has been linked to birth defects in Brazil, Reuters reported.

The mosquito-borne virus has been linked to microcephaly, a condition that causes unusually small heads that may lead to developmental problems. Brazil has confirmed over 500 cases of microcephaly and attributes most of the cases to Zika infections in the mothers.