CRS INSIGHT
Zika Virus: Global Health Considerations
February 9, 2016 (IN10433)
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Related Author
Tiaji Salaam-Blyther
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Tiaji Salaam-Blyther, Specialist in Global Health (tsalaam@crs.loc.gov, 7-7677)
Background
Zika is a virus that is primarily spread by Aedes mosquitoes—the same mosquitoes that transmit dengue, chikungunya,
and yellow fever. Zika transmission has also been documented from mother to child during pregnancy, as well as
through sexual intercourse, blood transfusions, and laboratory exposure. Scientists first identified the virus in 1947
among monkeys living in the Ugandan Zika forest. Five years later, human cases were detected in Uganda and
Tanzania. The first human cases outside of Africa were diagnosed in the Pacific in 2007 and in Latin America in 2015.
The ongoing outbreak in Latin America began in Brazil in May 2015 and has since spread to 26 countries and
territories in the region. Health experts predict that the virus will likely spread to all countries in the Western
Hemisphere except Canada and Chile, the only countries in the region without Aedes mosquitoes. No instances of local
transmission have been reported in the continental United States, but cases have been reported among travelers who
visited Central and South America, and transmission is ongoing in Puerto Rico. Outside of Latin America, Cape Verde
—islands off the West African coast—has ongoing transmission and Samoa—islands in the Western Pacific—has
reported less than a dozen imported cases.
Figure 1. Countries and Territories with Zika Cases in the Americas
(January 31-February 6, 2016)
Source: Created by CRS from PAHO and CDC maps of Zika cases at http://www.paho.org and
http://www.cdc.gov/zika/geo/index.html, accessed on February 9, 2016.
Scientists are unsure how many people have been affected by the 2015 outbreak in Latin America. Experts at the World
Health Organization (WHO) and its regional office for the Americas, the Pan American Health Organization (PAHO),
cite several factors that complicate efforts to count Zika cases, including the following:
A relatively small proportion (about 1 in 4) of infected people develop symptoms.
The virus is only detectable for a few days in infected people's blood.
Current tests cannot definitively distinguish Zika from similar viruses, such as dengue and chikungunya.
Zika typically causes mild symptoms, including fever, rash, and conjunctivitis, which usually last up to one week.
Hospitalization and death following infection are rare. There are neither antiviral treatments for the disease nor
vaccines to prevent infection.
Health experts are uncertain whether Zika causes microcephaly, a potentially severe birth defect involving brain
damage. Since October 2015, Brazilian officials have reported more than 4,000 cases of microcephaly in areas with
ongoing Zika transmission, up from roughly 150 cases in previous years. Health officials are concerned that this may be
a result of infection in the fetus when a pregnant woman is infected.
U.S. and International Responses
Although a direct link between Zika infection and birth defects has not been definitively established, the suspected
causality has caused WHO to raise the risk profile of Zika "from a mild threat to one of alarming proportions." The
WHO Director-General found four issues particularly troubling:
the possible association of infection with birth malformations and neurological syndromes;
the potential for further international spread given the wide geographical distribution of the mosquito vector;
the lack of population immunity in newly affected areas; and
the absence of vaccines, specific treatments, and rapid diagnostic tests.
Citing these concerns and possible increases in mosquito populations due to El Niño, WHO Director-General Margaret
Chan convened an Emergency Committee meeting on February 1, 2016, under the International Health Regulations and
declared that the ongoing outbreak is a public health emergency of international concern (PHEIC). A PHEIC
declaration indicates that the health event "may require immediate international action." Scientists are also considering
the risk of infection to and further global spread of the virus by visitors to Brazil for the 2016 Summer Olympics.
WHO and PAHO are supporting affected countries to detect, respond, and prevent Zika infections by
strengthening disease surveillance;
building laboratory capacity to detect the virus;
bolstering mosquito control;
preparing recommendations for the care of infected persons; and
defining and supporting priority research areas.
Several U.S. agencies are collaborating with international agencies to research the modes of transmission and
complications that may arise following infection. The U.S. Centers for Disease Control and Prevention (CDC) and
PAHO, for example, are partnering with Brazil's Ministry of Health to study the impacts of Zika during pregnancy,
including a possible link to microcephaly. CDC and the National Institutes of Health (NIH) are working on an
improved diagnostic test. The Department of Defense (DOD) is providing information to NIH to facilitate the
development of vaccines and effective treatments.
U.S. Funding for Global Disease Threats
International outbreaks of new and reemerging diseases have prompted calls for more funds to expand global capacity to
address diseases like Zika. In February 2014, Kathleen Sebelius, the former Secretary of the U.S. Department of Health
and Human Services, and WHO Director-General Margaret Chan announced the Global Health Security Agenda
(GHSA), an international effort to accelerate IHR implementation and pandemic preparedness worldwide, particularly
in low-resource countries. U.S. resources that are available for addressing diseases with pandemic potential globally,
like the ongoing Zika outbreak, are outlined in Table 1. President Barack Obama has requested $1.8 billion to address
the ongoing Zika outbreak, including over $375 million for international efforts. The Zika Emergency request is
outlined in Table 2.
Table 1. International Pandemic Preparedness Funds: FY2014FY2016
(current $U.S. millions)
Agency/Program
USAID Global
Health Security
CDC Global Public
Health Protection
FY2014
Enacted
FY2015
Enacted
FY2016
Request
FY2016
Enacted
73
73
50
73
63
55
77
55
Source: State-Foreign Operations and CDC Congressional Budget
Justifications and the FY2016 Consolidated Appropriations.
Notes: Includes only funds appropriated for international pandemic
preparedness. U.S. agencies may use additional resources from
other accounts to address global disease outbreaks worldwide.
Through FY2015 Ebola Emergency appropriations, Congress
provided $597 million to CDC to establish and strengthen National
Public Health Institutes and for other international preparedness
activities. It is unclear whether these resources are being used for
ongoing Zika responses.
Table 2. Zika Emergency Request
Agency/Activity
U.S. Centers for Disease Control and Prevention
(CDC) – domestic response
Puerto Rico's Medicaid Federal Medical
Assistance Percentage (FMAP) – health services
for pregnant women
National Institutes of Health (NIH) and Food and
Drug Administration (FDA) – Vaccine Research
and Diagnostic Development
Establishment of an Urgent and Emerging Threat
Fund at HHS to support State responses and
other emerging needs related to Zika
U.S. Agency for International Development
(USAID) – support affected countries to respond
to Zika outbreak
U.S. Department of State – support for U.S.
citizens in affected countries, as well as Zika
responses by the World Health Organization
(WHO) and the Pan American Health
Organization (PAHO)
Amount
$828 million
$250 million
$200 million
$210 million
$335 million
$41 million
Source: White House, Preparing for and Responding to the Zika Virus
at Home and Abroad, Fact Sheet, February 8, 2016.