National Biosurveillance Integration Center
Office of Health Affairs
SPOT REPORT
29 January 2016
ZIKA VIRUS IN THE AMERICAS
STATE, LOCAL, TRIBAL, & TERRITORIAL EDITION
Current Event Status (Worsening)
Since May 2015, when locally-acquired Zika virus detection
was reported in Brazil, Zika activity has rapidly spread to
additional countries throughout the region. As of 29 January,
locally-acquired Zika virus cases have been reported in 25
countries and territories in the Americas. Several countries,
including Brazil and Colombia, have reported rapid spread
throughout the population after first detection of the virus,
whereas other countries, such as Bolivia and Honduras, have
reported sporadic transmission following recent introduction.
To date, local transmission has not been documented in the
U.S. outside of Puerto Rico and the U.S. Virgin Islands.
Worsening
No Change
Improving
Why We Are Reporting on This Event
Detections of locally-acquired Zika virus transmission in
the Americas represent an expansion of the disease to new
geographic areas. Zika virus has symptoms similar to
chikungunya and dengue fever, which are both present in
numerous countries in the region, making differential
diagnosis difficult. Zika virus has the potential to spread
throughout the region in a pattern similar to that of
chikungunya and dengue.
NBIC previously produced a Biosurveillance Event Report
with further information 22 December 2015. An update is
anticipated the week of 01-05 February.
Undetermined
SITUATION OVERVIEW
Zika virus was first detected in the Americas in February 2014 on Easter Island (Chile), where cases continued until June 2014. In
May of 2015, locally-acquired transmission of Zika virus was detected in Brazil, where cases have now been confirmed in a majority
of states. As a result of enhanced surveillance and testing in the region, locally-acquired Zika virus transmission has now also been
confirmed in additional countries and territories in the Americas including: Barbados, Bolivia, Colombia, Costa Rica, Curaçao,
Dominican Republic, Ecuador, El Salvador, French Guiana, Guadeloupe, Guatemala, Guyana, Haiti, Honduras, Martinique, Mexico,
Nicaragua, Panama, Paraguay, Saint Martin, Suriname, U.S. (Puerto Rico and U.S. Virgin Islands), and Venezuela. Local and national
health authorities within affected and border countries are increasing efforts in surveillance, detection, and prevention of Zika virus
transmission.
Map of countries and territories reporting local Zika virus transmission in the Americas (Curacao and U.S. Virgin Islands not visible. Costa Rica not shown)
State, Local, Tribal, & Territorial Edition
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The World Health Organization (WHO) estimates that 0.5-1.5 million cases have occurred in the region and that cases could reach 3-4
million within a year. The WHO will convene an IHR Emergency Committee meeting on 01 February 2016 to discuss Zika virus and
the observed increase in neurological disorders and neonatal malformations, such as microcephaly, that may be related.
In the U.S., the Centers for Disease Control and Prevention (CDC) has reported at least 31 imported Zika cases in 11 states and the
District of Columbia since 2015, but local transmission has not been documented in the U.S. outside of Puerto Rico and the U.S.
Virgin Islands.
Because the Aedes mosquitoes that transmit Zika virus are present throughout most of the world, the CDC predicts that outbreaks are
likely to spread to new countries. The U.S. CDC has issued travel health notices, Alert Level 2: Practice Enhanced Precautions, for
Mexico, the Caribbean (Barbados, Dominican Republic, Guadeloupe, Haiti, Martinique, Puerto Rico, Saint Martin, U.S. Virgin
Islands), Central America (Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, Panama), and South America (Bolivia, Brazil,
Colombia, Ecuador, French Guiana, Guyana, Paraguay, Suriname, Venezuela) due to Zika virus. The travel alerts caution all travelers
to protect themselves from mosquito bites. The CDC issued interim recommendations that pregnant women, in any trimester, consider
postponing travel to any area where local Zika transmission is ongoing. The interim recommendations also note that women who are
trying to become pregnant should talk to their doctor prior to travel and strictly follow steps to prevent mosquito bites during travel.
WHAT WE KNOW
Transmission
Zika is an emerging infection transmitted by Aedes mosquitoes, the same mosquito vector as dengue fever and chikungunya. For Zika
transmission to occur, an infected person must be bitten by a mosquito while Zika virus is in their bloodstream. That infected
mosquito must then bite an uninfected person for the virus to spread. Rarely, a mother who is already infected with Zika near the time
of delivery can pass the virus to her newborn around the time of birth, and possibly earlier in gestation. No cases have been reported of
Zika spread through breastfeeding, although Zika virus has been found in breast milk. Spread of Zika virus has been documented
through blood transfusion and sexual contact.
Symptoms
Approximately 1 in 5 people who are infected with Zika virus develop symptoms. The symptoms of Zika virus disease (Zika) are
commonly mild and can include fever, rash, joint pain, and conjunctivitis (red eyes). The illness is usually mild, with symptoms
ranging in duration 2-7 days. More serious symptoms requiring hospitalization are uncommon and deaths are rare.
Prevention and Treatment
No vaccines or treatments are available to prevent or treat Zika infections. Mosquito bite avoidance and prevention can reduce the
chances of being bitten by an infected mosquito.
Basic Mosquito Bite Preventive Measures
• Cover as much exposed skin as possible (e.g., wear long sleeves and long pants to cover arms and legs, especially during
early morning and late afternoon).
• If using both sunscreen and insect repellent, apply the sunscreen first and then the repellent.
• Apply repellent containing DEET concentration 30 to 35%, picaridin, IR3535, oil of lemon eucalyptus, or para-menthanediol to exposed skin. Follow application and reapplication instruction per manufacturer. Do not spray insect repellent on the
skin under your clothing.
• Apply permethrin (concentration 20% or greater) to clothing, bedding, and mosquito netting.
• Use air conditioning or window/door screens to keep mosquitoes outside. If you are not able to protect yourself from
mosquitoes inside your home or hotel, sleep under a mosquito bed net.
• Help reduce the number of mosquitoes inside and outside homes or hotel rooms by emptying standing water from containers
such as flowerpots or buckets.
If a person develops symptoms of a Zika virus infection, the treatment is supportive.
• Get plenty of rest
• Drink fluids to prevent dehydration
• To relieve pain and fever take medications such as acetaminophen.
• Do not take aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs), like ibuprofen and naproxen. These
medications should be avoided until dengue can be ruled out to reduce the risk of bleeding.
State, Local, Tribal, & Territorial Edition
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WHAT WE DON’T KNOW
Possible Association with Birth Defects and Neurological Disease
A recent hypothesis links Zika virus to an increase in severe birth defects, particularly in Brazil. An observational increase in babies
diagnosed with microcephaly, a medical condition in which the circumference of the head is smaller than normal because the brain has
not developed properly or has stopped growing, was noted in areas that had reported Zika virus. However, a definitive association has
not been shown. Further study into the possible association is ongoing in Brazil and other areas.
Clinical observations and clinical laboratory results have discovered evidence of Zika virus in a small number of babies born with
microcephaly as well as evidence suggesting that Zika virus can cross the placenta from mother to child during pregnancy. Further, it
is unclear when during pregnancy a fetus is most at risk for adverse outcomes if the mother is infected with Zika virus. These findings
are limited, but concerning. These results have prompted the U.S. CDC as well as the WHO to take even the possibility of negative
effects of Zika virus on fetuses seriously.
Additionally, health officials are investigating a possible link between Zika virus infection and Guillain-Barré Syndrome (GBS), a
disorder in which the body's immune system attacks part of the peripheral nervous system. Several countries in the Americas have
reported an increase in GBS following the introduction of Zika virus, and similar findings have been noted in previous outbreaks.
However, the association between Zika and GBS is still under investigation and has not been confirmed.
Immunity
The length of immunity following Zika virus infections is considered to be long term. However, there is a lack of research available on
Zika. The definitive length of immunity conferred following Zika infection is currently unknown.
Routes of Transmission
While transmission of Zika has been documented through sexual contact and Zika virus has been detected in semen, it is still
undetermined how long Zika can be transmitted through sexual contact and how long Zika is remains present in semen.
Mosquito Vectors
While Aedes aegypti mosquitoes are a known vector for the virus and Aedes albopictus has been shown previously to be a competent
vector, it is not known if other mosquitoes might be able to transmit the virus. Researchers in Brazil are investigating if Culex
mosquitoes are competent vectors as well. Culex mosquitoes have not previously shown the capability to transmit Zika. Each
mosquito species has a specific geographical range, which makes determining the transmissibility of Zika virus via other mosquito
species important to understanding the potential areas of concern for continued spread.
State, Local, Tribal, & Territorial Edition
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