The United States is expecting more than 4 million cases of the Zika virus to occur in just the Western hemisphere, with over 100 cases having been reported in America as of February, according to a new government oversight report, which further disclosed that the origins and transmission of the virus are still not "fully understood."
The U.S. Centers for Disease Control and Prevention (CDC) have recorded "107 cases of continental U.S. travel-associated Zika virus" as of Feb. 24, according to the report, which notes that several U.S. states have mosquito populations capable of transmitting the virus. At least 39 additional cases have been reported in U.S. territories.
Government officials warned that the virus is likely to spread throughout the Americas, with intelligence community insiders predicting more than 4 million cases in the Western hemisphere alone.
As the Zika virus outbreak reaches "epidemic levels," the CDC is warning that aspects of the disease have yet to be understood. This includes information about Zika’s transmission.
"The virus has continued to spread to the Americas, with the outbreak in Brazil that began in May 2015 and is ongoing," according to the report. "Zika has spread to Mexico, Central America, the Caribbean, and South America, where the outbreak has reached epidemic levels."
Zika, which primarily is transmitted through infected mosquitos and has been tied to various birth defects, has been spotted "in the Commonwealth of Puerto Rico, the U.S. Virgin Islands, and American Samoa," according to the report.
"The first locally-acquired case of Zika virus disease in Puerto Rico was reported in December of 2015," with even more cases identified in the ensuing months.
"Through late January of 2016, about 30 additional laboratory-confirmed cases were identified in Puerto Rico, including one pregnant woman," the report disclosed. "In January of 2016, the CDC issued travel guidance for travel to affected countries, including the use of enhanced precautions for all travelers, as well as the recommendation that pregnant women postpone travel to affected areas."
The CDC also has determined the virus can be spread through sexual contact.
"Sexual transmission of the disease— acquired outside of the United States—has been reported in the United States," according to the report. "As of February 23, 2016, the CDC and state public health departments are investigating 14 additional reports of possible sexual transmission of the virus, including several involving pregnant women."
The CDC remains particularly concerned that the virus could taint the U.S. blood supply.
"While there have been no reports to date of Zika virus entering the U.S. blood supply, the risk of blood transmission is considered high based on the most current scientific research of how Zika virus and similar viruses (i.e. flaviviruses) are spread, as well as recent reports of transfusion-associated infection outside of the United States," according to the report.
The virus is particularly difficult to spot and contain because a large number of infected individuals do not exhibit symptoms.
"Researchers have reported that an estimated 80 percent of the individuals infected with the Zika virus are asymptomatic, that is, they have the virus but do not manifest clinical symptoms," the report found.
This has led governments to significantly undercount the number of infected individuals.
The United States lacks methods to definitively test for the virus for a large number of individuals.
The CDC relies on two Zika diagnostic tests. One test can only detect infection while an individual is showing symptoms. The second test is more specific, but is "cumbersome and not suitable for screening a large number of individuals," according the report.
There are currently no commercially available diagnostic tests in the United States.