I recently had a client show me a mosquito bite and ask me if it looked like Zika. I had no clue. I told him if he was concerned to check with his doctor, but what do I know?
Zika virus—is it a momentary distraction, an overblown news blip? Is it a rare-but-tragic contributor to a set of serious birth defects? Or is it a dangerous mosquito-borne contagion that threatens to overwhelm the globe and infect us all?
Pathology Perspective articles are usually intended to be “evergreen”—that is, not bound to a specific season or trend. This one is an exception, both because the information is important and changing quickly, and because it is relevant to a specific event: the 2016 Summer Olympic Games in Rio de Janeiro, Brazil. This means Brazil, the first location in the continental Americas where the Zika virus has been identified, was an international travel hub, and traffic into and out of the country may create pathways for this virus and its complications to become more firmly established around the globe.
This column will focus on what we understand about the activity of Zika virus in North America, but be aware that this is a worldwide phenomenon, and it has already been declared a global pandemic (see Zika History).

What is Zika?
Zika virus is a single-strand ribonucleic acid (RNA) vector-borne virus, similar to viruses seen with dengue fever, chikungunya, and yellow fever. Like other viruses of this type, it invades the cytoplasm of its target cells and reprograms the function of those cells to make them literal virus factories. Infected cells release virions: viral particles that can spread to more cells in the body or to other hosts altogether. With Zika virus, this happens mainly through mosquitoes biting infected people and carrying the virus to uninfected people, and also through sexual activity and transplacental pathways.

Transmission
Zika virus begins as a vector-borne infection, usually carried by some Aedes species of mosquitoes. Many such species are found in tropical zones throughout the world, but there are two subtypes that are common in up to 30 states in the United States: Aedes aegypti is mostly in tropical areas and cannot tolerate cold weather, and Aedes albopictus, which is hardier, and can survive cooler temperatures. Both of these mosquito species are also carriers of other related illnesses, particularly dengue fever.
Zika spreads from one host to another by way of mosquito bites: an insect picks up the virus from one person’s blood and injects it into another. Aedes mosquitoes are aggressive feeders, often moving rapidly from one target to another in rapid succession, and they are most active during the daytime (as opposed to other mosquito species that are most active in the early morning or twilight hours).
Zika is also spread through sexual activity. This is new territory; no other vector-borne viruses have been seen to share this characteristic, so scientists are still exploring this phenomenon. Early tests suggest that the virus is active and transmissible in men longer than in women.  
Crossplacental infection from mother to fetus is the pathway that leads to Zika-related birth defects. However, breast milk does not appear to be a transmission pathway, so mothers in Zika-affected areas are still encouraged to breastfeed their babies.
It is suspected, but not fully confirmed, that the virus may also be spread by way of contaminated blood transfusions or organ transplants.

Signs, Symptoms, and Diagnosis
One of the peculiarities of Zika virus is that it is usually a totally silent infection. It can be transmitted, trigger an immune system response, and expelled, all without creating any symptoms whatsoever. Researchers suspect that this occurs in up to 80 percent of all Zika cases, which suggests that the numbers we see reported about laboratory-identified cases are probably underestimating the spread of this infection.
If it causes any symptoms, Zika resembles flu: it may involve fever, headache, fatigue, and body aches. It can also cause conjunctivitis (inflammation of the conjunctiva of the eye) and a sometimes-itchy rash that may appear on the face, palms, soles, extremities, or torso.
The course of the infection is fairly brief. The incubation period between exposure and signs of infection is between 3–12 days. Symptoms, if any occur, usually last for less than a week.
Zika can be diagnosed with a blood test or by urinalysis. Tests are sometimes inaccurate, however, and it can be difficult to distinguish from dengue fever.

Two Main Complications
Zika virus itself does not appear to be dangerous to children and adults. The vast majority of infected people have no symptoms, and almost everyone can expect full recovery. However, this virus is associated with two serious complications: a set of birth defects that impact how the brain grows and a risk for Guillain-Barré Syndrome (GBS)—an autoimmune reaction to viral infection.

Birth Defects
For reasons that are not clear, some women who contract Zika infections while they are pregnant give birth to babies with a condition called microcephaly (translated literally, “small head”) or other defects that impair cognition, hearing, and vision.
Microcephaly is not exclusive to babies of mothers infected with Zika; it can also be caused by other viral infections, malnutrition, and other factors. The typical rate of microcephaly is about 2–12 per every 10,000 live births. However, in areas where Zika is present, that rate spikes substantially higher; scientists estimate that up to 15 percent of infected pregnant women may give birth to a baby with these problems, as opposed to the .0012 percent that would otherwise be expected.
Between the beginning of the Brazilian outbreak of Zika in May 2015 and autumn 2016, more than 1,400 babies with Zika-related microcephaly have been born in Brazil. Local governments of several South American countries are now encouraging all their female citizens to delay conception for two years, by which time it is hoped this situation will be more under control.
Now, several months after the initial wave, the expected spike in births of microcephalic babies in Brazil has not occurred. It could be that it is still to come, or that many cases of birth defects are multi-factoral, and exposure to Zika is only one contributor. Epidemiologists are watching this phenomenon carefully.
So far 18 Zika-affected babies have been born in the United States (with an additional five stillbirths), and at least one affected child has been born in Europe.
The birth defects associated with Zika virus occur on a continuum of severity. Microcephaly can cause difficulties and delays in balance, communication, eating, movement, and intellectual development. Some children have seizure disorders as well. At the mild end of the spectrum, a child may have only minor problems and incapacity. But severe cases may cause completely disabling limitations or stillbirth.

Guillain-Barré Syndrome
GBS is an autoimmune attack on the myelin of peripheral neurons. It is an occasional complication of viral infections, and it is sometimes seen with severe cases of Zika virus. So far, 34 cases of Zika-related GBS have been identified in the continental United States. Here are some basics:
• It can affect myelin sheaths on peripheral neurons in the trunk and extremities.
• It can cause progressive weakness that moves from the extremities to the core; this may lead to temporary dependence on a respirator.
• It is usually self-limiting and resolves without permanent damage.
• If it is treated early, the duration and severity of GBS can be managed.

Zika Prevention and Treatment
At this point, the best way to prevent Zika infections is to avoid travel to areas where the virus is present in the local mosquito population. This also shows how important it is for a person who may have been infected to avoid being bitten by mosquitoes that can carry the virus to new human hosts. Limiting mosquito bites is a crucial step in managing the spread of Zika in humans.
The Centers for Disease Control recommend several mosquito repellants including DEET, picaridin, IR3535, oil of lemon eucalyptus, and para-methane-diol, but not all of these are safe for infants and young children.
The other way to slow the movement of Zika through the human population is by practicing abstinence or barrier methods of safe sex. Scientists recommend practicing safe sex and delaying attempts to conceive a child for at least six months after being exposed to Zika or having the infection, in order to avoid spreading the virus to partners or to unborn children.
As a viral infection, Zika has no treatment other than supportive therapies: rest, fluids, and symptomatic control. It does not respond to antibiotics. Fever, headache, and body aches can be managed with acetaminophen. This is preferable to nonsteroidal anti-inflammatory drugs (NSAIDs), because sometimes Zika can be difficult to distinguish from dengue fever, and NSAIDs increase the risk of hemorrhaging in people with dengue fever.

General Questions About Zika
• How long is the virus contagious?
We don’t know; scientists suggest that a six-month period is safe to prevent spreading the virus through sexual activity.
• Does one infection impart lifelong immunity?
We don’t know, but it looks like this may be the case.
• Is it possible to be co-infected with Zika and other vector-borne viruses?
Yes, but this appears to be rare, and has not been documented in the United States.
• Is a vaccine possible?
Multiple vaccines are in development and in safety trials. They are not expected to be approved for widespread use for at least a year.
Questions About Massage Therapy and Zika
Zika virus has almost no practical implications for massage therapy, as long as clients are not feverish and don’t have a rash.  
• If a person has Zika symptoms (body aches, fever, headache, rash, red eyes) should they reschedule their massage appointment?
Yes, as is true for any viral infection.
• Can a massage therapist catch Zika from a client?
No. The virus is only transmitted by having sex or being bitten by a carrier mosquito.
• Can massage spread Zika from one person to another?
No.
• Can massage make Zika worse if a person has no symptoms?
No.
• If I massage a pregnant woman who has Zika, could I increase the risk of birth defects?
We have no reasons to think so.

MT Takeaways
Zika is spreading quickly around the planet, to wherever the carrier mosquitoes can make a home. At this time, we have no vaccine, and we can only limit its effect on humans through safe-sex practices and mosquito abatement. Its worst complications impact developing fetuses, so it is important for women who might become pregnant to be aware of serious potential risks to their babies. That said, the vast majority of people who contract a Zika infection will have no symptoms and no long-term consequences related to the virus.
Massage therapists have an obligation to be a source of accurate, reliable health-related information. If you have clients who are worried about Zika, now you have some information to answer some of their most pressing questions. Here are the key takeaways:
1. If there’s a chance of Zika exposure, it is important to practice safe sex for at least six months to avoid the risk of spreading it to partners.
2. If there’s a chance that a pregnancy could overlap a Zika exposure, discuss this with your health-care providers as soon as possible.
3. If you have signs of GBS (sudden onset of progressive weakness in the extremities, balance problems, incontinence), consult your health-care provider as soon as possible.
4. Try to avoid being bitten by mosquitoes.
5. Otherwise, don’t worry about it!

Ruth Werner, BCTMB, is a former massage therapist, a writer, and an NCBTMB-approved provider of continuing education. She wrote A Massage Therapist’s Guide to Pathology (Lippincott Williams & Wilkins, 2016), now in its sixth edition, which is used in massage schools worldwide. Werner is available at www.ruthwerner.com.