GAO Zika Report

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EMERGING INFECTIOUS DISEASES:

Preliminary Observations on the Zika Virus Outbreak

GAO-16-470T: Published: Mar 2, 2016. Publicly Released: Mar 2, 2016.

http://www.gao.gov/products/GAO-16-470T?utm_medium=email&utm_source=govdelivery

 

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Additional Materials:

• Highlights Page:
  •  (PDF, 1 page)
• Full Report:
  •  (PDF, 30 pages)

Contact:

Timothy M. Persons, Ph.D.
(202) 512- 6412
[email protected]

 

Office of Public Affairs
(202) 512-4800
[email protected]

 

What GAO Found

While several countries have reported outbreaks of Zika virus disease—which appear to be primarily transmitted to humans by mosquitos—unanswered questions remain regarding the epidemiology and transmission of the disease. Many factors—including a large number of asymptomatic patients and patients with mild symptoms, and a lack of a consistent international case definition of Zika virus disease—complicate understanding of the virus and may hinder responses to the current outbreak. For example, an estimated 80 percent of individuals infected with the Zika virus may not manifest clinical symptoms. As a result, incidence of the infection may be underestimated. Questions also remain regarding the strength of the association between Zika virus infection and two other conditions: microcephaly and Guillain-Barré syndrome.

A lack of validated diagnostic tests, consistent international case definitions, and trend information may also contribute to difficulty in estimating the prevalence of the virus. The United States uses two diagnostic tests for Zika, and according to the U.S. Centers for Disease Control and Prevention (CDC), while there are no commercially-available diagnostic tests for Zika, an antibody-based test for Zika virus was recently authorized for Emergency Use by the U.S. Food and Drug Administration. Diagnosing Zika virus infection is also complicated because it is difficult to differentiate it from other similar diseases, such as dengue or yellow fever. For example, a person previously infected with dengue could be falsely identified as also having been exposed to the Zika virus (and vice-versa). Moreover, the World Health Organization has acknowledged the need for a consistent case definition—that is, a set of uniform criteria to define the disease for public health surveillance and to determine who is included in the count and who is excluded. Additionally, a lack of pattern and trend data has made surveillance challenging.

Because Zika virus disease cannot yet be prevented by drugs or vaccines, vector (mosquito) control remains a critical factor in preventing and mitigating the occurrence of this disease. There are three methods for mosquito control: (1) standing water treatment, (2) insecticides, and (3) emerging technologies. Mosquito control has been achieved in some locations by methods such as reducing or chemically-treating water sources where mosquitoes breed or mature, or by insecticide dispersal. Emerging technologies, including biological control methods—such as infecting mosquitoes with bacteria— genetically-modified mosquitoes, and auto-dissemination traps, show some promise but are still in development and testing phases.

The National Institutes of Health (NIH) and the CDC have identified several high priority areas of research. Research priorities include basic research to understand viral replication, pathogenesis, and transmission, as well as the biology of the mosquito vectors; potential interactions with co-infections such as dengue and yellow fever viruses; linkages between Zika and the birth defect microcephaly; improving diagnostic tests; vaccine development; and novel vector control methods. These efforts are ambitious, and agencies may face challenges in implementing this agenda.

Why GAO Did This Study

Emerging infectious diseases constitute a clear and persistent threat to the health and well-being of people and animals around the world. The Zika virus, which at present appears to be primarily transmitted to humans by infected mosquitos, can cause symptoms including fever, rash, and joint pain. A large ongoing outbreak is occurring in Brazil that started in May 2015. As of February 24, 2016, over 100 cases of U.S. travel-associated Zika virus disease cases have been reported.

Due to concerns about its potential impact, you asked GAO to present preliminary observations on the Zika virus. This statement addresses (1) the epidemiology and transmission of the Zika virus disease, including reporting on the incidence of disease and what is known about its link to microcephaly; (2) detection and testing methods; (3) methods for mosquito control; and (4) the proposed federal research agenda as it relates to the Zika virus and Zika virus disease.

To report on these questions, GAO reviewed relevant peer-reviewed scientific literature, epidemiological alerts, agency documents, and prior GAO work from 2003-2016 on related topics; consulted experts in the fields of virology, infectious diseases, and vector control, including industry representatives; and interviewed officials of the CDC and NIH.

What GAO Recommends

GAO is not making recommendations at this time.

For more information, contact Timothy Persons at or [email protected].

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U.S. Anticipates More Than 4 Million Cases of Zika Virus

As disease hits ‘epidemic levels,’ officials unsure about virus’ origins, transmission

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BY: Adam Kredo 
March 2, 2016 1:58 pm

 

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.

http://freebeacon.com/national-security/u-s-anticipates-more-than-4-million-cases-of-zika-virus/