Zika Virus Disease
The Zika virus is a type of mosquito-borne flavivirus that is typically transmitted by the Aedes species of mosquitos. Although most people do not have any symptoms, those who do have symptoms typically experience mild, flu-like symptoms. Pregnant women are believed to be at risk of pregnancy complications if they contract Zika virus disease during pregnancy. In particular, microcephaly (abnormally small skull) is a serious birth defect that has been linked to Zika infections in pregnant women. In February 2016, the World Health Organization declared Zika virus disease to be an international public health emergency.
Overview
Seriousne Prevalence in USA Lifetime Cost
Mild Rare Low
The Zika virus is a part of the Flaviviridae family of viruses, which also includes the viruses that cause West Nile, dengue fever, yellow fever, and Japanese encephalitis. The Zika virus was first discovered in 1948 in a rhesus monkey located in the Zika Forest in Uganda. By 1981 it had been seen in patients in parts of Africa (including Uganda, Nigeria, Tanzania, Egypt, Central African Republic, Sierra Leone, and Gabon) and parts of South and Southeast Asia (including India, Malaysia, Thailand, Vietnam, Indonesia, and the Philippines).
Outbreaks of Zika virus disease have been reported on the island of Yap in Micronesia in 2007 and in French Polynesia in 2014. Starting in May 2015, an outbreak of the virus was reported in South America.
The Zika virus can spread from an infected person to an uninfected person by way of mosquito bites. The Aedes species of mosquito is an aggressive daytime feeder that tends to bite multiple people in a row, transferring the virus between humans. There have also been reports of the virus being transmitted from mother to fetus before the baby is born, from mother to baby during childbirth, through sexual contact, and from blood transfusions.
Approximately 1 in 5 people (20%) who become infected with the Zika virus will experience mild flu-like symptoms, which can include fever, itchy rashes, muscle and joint aches, headaches, fatigue, and conjunctivitis (red, irritated eyes). The symptoms typically appear within a week (2 to 7 days) after infection and last up to around a week.
The greatest concern regarding Zika virus disease is the infection’s suspected link to a serious condition called microcephaly (abnormally small skull) in babies born to women who have contracted Zika virus disease during pregnancy. There have also been reports of Guillain-Barre syndrome following Zika virus infection. Guillain-Barre is a condition where the body’s immune system attacks the nerves, causing muscle weakness and possibly paralysis. It’s not known exactly what causes Guillain-Barre, though there are a number of viruses that have been reported to trigger it.
Zika virus disease is diagnosed through a blood test. It is recommended that certain people see a physician or go to a clinic if they are at risk of infection:
Individuals who have recently traveled to areas where the outbreak has been reported and who are experiencing flu-like symptoms should speak to a healthcare provider. This is in order to rule out other serious infections, such as malaria.
Women who are pregnant or who are planning to become pregnant and who have recently traveled to high-risk areas should check with their prenatal care team for more information about the risks associated with Zika infection.
There is currently no treatment or vaccine available for the Zika virus. Individuals in high risk areas should take precautions to avoid exposure to mosquito bites, including wearing long-sleeved shirts and long pants, wearing insect repellant that contains at least 25% DEET, avoiding standing bodies of water, and sleeping under a mosquito net.
In February 2016, the World Health Organization (WHO) declared Zika to be an international public health emergency. This was in response to the 2014 outbreak in French Polynesia and the 2015 outbreak in Brazil. These outbreaks were linked with a significant increase in cases of microcephaly and other neurological complications in babies born to women who had contracted Zika virus disease during pregnancy. The WHO emphasized the need to fast-track research on Zika infections in order to better understand the link between Zika and pregnancy complications, including microcephaly. Other necessary research includes the need for a better understanding of how the infection spreads from person to person, where the virus occurs geographically, how to diagnose it quickly and accurately, and how to control mosquito populations that transmit the virus. The WHO encouraged the international scientific community to work on developing a reliable and safe vaccine.
Causes
Environmental Lifestyle
The Zika virus is a type of flavivirus that was first discovered in a rhesus monkey in the Zika Forest of Uganda in 1947. Prior to the 2015 outbreak, Zika virus disease had been documented in parts of Africa, South Asia, Southeast Asia, and the Pacific Islands. The virus is known to infect both humans and non-human primates.
Transmission by Mosquito
The Zika virus is primarily spread between humans by the Aedes species of mosquito, which are present throughout many parts of the world. These are the same types of mosquitos that spread the viruses that cause dengue fever, chikungunya, and yellow fever.
Aedes mosquitos are aggressive feeders that tend to bite several people in succession, which can spread the virus from an infected person to an uninfected person.
Aedes aegypti mosquitos are found in warmer climates and cannot survive cold weather.
Aedes albopictus mosquitos can survive in cooler climates.
Aedes mosquitos can travel between regions by accidentally being transported by humans, such as in a vehicle or with cargo.
Warm, wet weather and areas with standing or stagnant water (puddles, ponds, bogs, reservoirs, etc.) make it easier for mosquitos to survive and breed. Unlike some other types of mosquitos, Aedes mosquitos are active during the daytime, particularly during mid-morning and from late afternoon until twilight.
Once a female Aedes mosquito has laid its eggs, the eggs can survive up to a year without water. It only takes a small amount of standing water for the eggs to hatch and mature into adult mosquitos.
Other Forms of Transmission
The Zika virus is primarily a mosquito-borne illness. However, in rare cases the Zika virus has been reported to spread by other means, including:
Through sexual contact
From mother to child through the placenta
From mother to child during childbirth
Via blood transfusion
To date there are no reports of the virus passing to an infant through a mother’s breast milk. Given the benefits of breastfeeding, women in areas affected by the Zika virus are encouraged to continue breastfeeding normally.
Affected Areas
Beginning in early 2016, the United States Centers for Disease Control and Prevention (CDC) advised pregnant women against traveling to certain countries where the Zika virus has been reported, and suggested screenings for pregnant women who have recently traveled to affected countries. Please check with your healthcare provider regarding current areas where the virus is known to have spread, since the lists are frequently updated.
The Aedes mosquitos that carry the Zika virus are known to live throughout South, Central, and North America. In February 2016, the World Health Organization (WHO) reported that the mosquitos can be found in all areas of these continents with the exception of mainland Chile and Canada, and that the remaining countries are likely to see cases of the virus within their borders during the course of the outbreak. Warm, wet weather conditions are favorable for mosquitos, meaning that weather patterns may affect how quickly and how far the virus spreads.
Symptoms
Primary Symptoms
Incubation Period
The period of time between when a person is infected and when symptoms first appear is called the incubation period. The incubation for the Zika virus is thought to be between a few days and a week. In other words, symptoms may begin to appear somewhere between 2 – 7 days after infection.
Mild, Flu-Like Symptoms
Most individuals who become infected with the Zika virus will not experience any symptoms.
Approximately 20% of people (1 in 5) who are exposed to the virus develop symptoms. Those who do become ill most often have only mild, flu-like symptoms. These can include:
Fever (usually low-grade)
Headaches
Body aches (muscle and joint aches)
Fatigue
Malaise
Rash, which may itch
Conjunctivitis (red eyes)
Symptoms typically don’t require any special treatment and will go away on their own within about a week (2 – 7 days).
If You Experience Symptoms of Zika Virus Disease
Symptoms of Zika virus disease are seldom serious enough to require hospitalization. However, anyone who is experiencing symptoms and who has recently been in an affected area should talk to a physician. This is important in order to help track the spread of the virus and to rule out dengue fever, which can have life-threatening complications (see the Diagnosis and Treatment sections for more information).
Women who are pregnant, are experiencing symptoms of Zika virus disease, and who have recently been in an area with reported cases of Zika virus disease should speak to their prenatal care team as soon as possible. Zika virus infections during pregnancy have been linked with serious complications in newborns (see the Complications section for more information).
Complications
Microcephaly
Women who are pregnant or who may become pregnant are advised to avoid or delay travel to areas affected by Zika virus infections if at all possible. If this is not possible, strict precautions should be taken to avoid mosquito bites (see the Prevention section for more information). This is because cases of Zika virus disease in pregnant women are believed to be linked with cases of microcephaly in newborn babies. Talk to your healthcare provider for an updated list of areas currently affected by the Zika virus outbreak, as the list is frequently updated.
Microcephaly is a condition where a baby’s head is too small for its age and body size. This is associated with an underdeveloped brain, since a baby’s skull typically grows as the brain grows. In other words, a small skull indicates that the brain is underdeveloped for the baby’s size and age.
Within the general population, between 2 to 12 out of 10,000 babies are born with microcephaly. However, between October 2015 and January 2016, over 4,000 new cases of microcephaly were reported during a Zika outbreak in Brazil. Although it’s not known for certain, it is strongly suspected that Zika virus infections in pregnant women can cause microcephaly and other serious pregnancy complications. Further research is needed to better understand the relationship between Zika virus infections and neurological complications in newborn babies.
Complications of microcephaly can range from mild to very severe, including:
Difficulties or delays with the development of movement and balance (such as rolling over, sitting up, crawling, standing, and walking)
Difficulties or delays with the development of communication (such as babbling, first words, and putting strings of words together)
Difficulties or delays with intellectual development
Difficulty feeding / chewing / swallowing
Hearing and/or vision problems
Seizures
Women who may have been exposed to the virus during pregnancy should seek a diagnosis and follow-up care immediately. It is recommended that pregnant women who have a confirmed diagnosis of Zika virus disease talk to an experienced obstetrician as soon as possible. The prenatal care team will want to monitor the pregnancy closely through regular ultrasound scans to track the baby’s development. Other healthcare professionals may also become involved, such as infectious disease specialists or neurologists who specialize in prenatal care.
Although Zika is not fully understood, it appears that the virus leaves the blood after about a week. It is not known for certain, but it is suspected that women who become pregnant after having recovered from a Zika infection are not at risk of pregnancy complications. However, as mentioned above there is still much research to be done in order to understand how Zika affects pregnant women and their babies. Therefore, the current recommendations are to:
Wait at least six months before trying to conceive if a woman has had a Zika infection.
Wait at least four weeks after returning from an area affected by the Zika outbreak before attempting to get pregnant for women who have not had an infection or flu-like symptoms.
Wait at least four weeks after returning from an area affected by the Zika outbreak before having unprotected sex in order to prevent sexual transmission (both males and females).
Guillain-Barre Syndrome
Guillain-Barre syndrome is a condition that is not well understood. Many cases begin after a person has had an infection. Zika virus infections have been reported to trigger Guillain-Barre syndrome in some people. The syndrome occurs when a person’s immune system begins to attack parts of the nervous system instead of the infection. It can occur at any age, even in otherwise healthy people.
Symptoms of Guillain-Barre syndrome are the result of damage to the nervous system, and can include:
Unusual or tingling sensations in the extremities (called paresthesia), including the toes, feet, ankles, fingers, hands, and wrists
Muscle weakness, particularly weakness that begins in the lower body and spreads upwards (the weakness can sometimes progress into paralysis)
Difficulty with balance, standing, and walking
Difficulty with speaking, chewing, swallowing, and facial expressions
Bowel/bladder incontinence
In severe cases, Guillain-Barre syndrome can affect heart rate, blood pressure, or even cause difficulty breathing. Symptoms tend to be the worst about 2-4 weeks after they begin and start to get better after about a month.
Symptoms of Guillain-Barre syndrome can become worse very rapidly. Anyone who is experiencing symptoms of Guillain-Barre following an infection should seek medical care right away.
Diagnosis
Diagnostic Procedures
Blood Test Physical Examination
Healthcare agencies are currently being asked to report any confirmed cases of Zika virus disease. Anyone who lives in or who has recently traveled to an area affected by Zika virus infections should talk to a healthcare provider. This is so that cases of Zika virus infections can be tracked, and so that other infections can be ruled out.
History and Physical
Diagnosis of any medical condition begins with a history and physical with a qualified and licensed healthcare provider. In order to diagnose a Zika virus infection, the healthcare provider will ask a series of questions. The intention of these questions is to determine whether the person has been exposed to the Zika virus, such as from a mosquito bite from a location where Zika virus infections have been reported. Since the virus can also be transmitted through sexual contact, the provider will want to know about any recent sexual contact with someone who may have an infection.
During the physical examination, the healthcare provider will look for signs and symptoms of Zika virus disease, such as rash and conjunctivitis (red, swollen eyes). He/She will want to know about any flu-like symptoms that could signal an infection (see the Symptoms section for more information).
Blood Testing
The Zika virus can be detected with a blood test. A small sample of blood is taken and sent to a laboratory that will look for signs of the virus in the sample. Additional blood tests may be ordered at the same time to look for signs of viruses that are similar to Zika, such as dengue fever or chikungunya.
Ruling Out Other Infections
For most people, a Zika virus infection will cause mild, flu-like symptoms that will go away within a week or so. However, getting an accurate diagnosis is important so that healthcare professionals can track the Zika virus as it spreads across different geographic locations.
It is also important to see a healthcare provider for a diagnosis since symptoms of Zika virus are similar to early symptoms of dengue. Dengue is spread by the same mosquitos that spread Zika, which means that someone who has lived in or traveled to an area where Zika is present may also have been exposed to dengue. Early identification and treatment of dengue is critical, as it can be a serious and life-threatening infection.
Similarly, malaria is a type of mosquito-borne infection that can be fatal if not identified and treated promptly. Like Zika and dengue, malaria tends to be found in warm, wet climates such as parts of Africa, Asia, the Pacific Islands, South America, and Central America.
Treatment
Treatment Procedures
Outpatient Treatment
There is currently no known treatment or cure for Zika virus disease. Most people who become infected with the Zika virus will not have any symptoms and will not require any treatment.
Treatment focuses on managing symptoms and taking care not to spread the infection to others, particularly pregnant women.
Symptom Management
Since there is no cure for Zika virus disease, treatment aims to keep the infected person as comfortable as possible until the symptoms go away. Steps to treat symptoms are similar to home care for flu, and include:
Get plenty of rest.
Drink plenty of fluids.
Take acetaminophen to treat fever, headache, and body aches.
Seek medical care if symptoms worsen.
A person who has a Zika virus infection should not take aspirin or any non-steroidal anti-inflammatory drugs (NSAIDs, such as naproxen or ibuprofen), as this can cause bleeding problems (see the Risks section for more information).
Antibiotics should never be used to treat a Zika virus infection. Antibiotics do not work against any viral infection, including Zika. Using antibiotics when they are not needed can cause serious, unnecessary side effects and lead to antibiotic resistance.
Avoid Infecting Others
Any person who has been exposed to the Zika virus will need to take strict precautions to avoid spreading the disease to others, especially to pregnant women. This means avoiding mosquito bites until a week after symptoms have first appeared. (See the Prevention section for more information about avoiding mosquito bites and preventing Zika virus infections).
Providers
Typically, you will visit a infectious disease specialist for zika virus disease. Below, you will find a list of nearby infectious disease specialists in your area, as well as nearby health facilities. You can also change the location or the specialty by using the filters.
Risks
Any person who suspects they may have been exposed to the Zika virus should avoid aspirin and any non-steroidal anti-inflammatory drugs (NSAIDs). Examples of NSAIDs include the popular over-the-counter drugs ibuprofen and naproxen. Aspirin and NSAIDs have been linked with hemorrhaging (bleeding) when taken to treat Zika virus symptoms.
Symptoms of a Zika virus infection should be treated with acetaminophen. Please see a healthcare provider if symptoms worsen or require further treatment.
Recovery
Only about 1 in 5 people who contract a Zika virus infection will experience any symptoms. The symptoms are typically mild and can be managed at home with acetaminophen. Symptoms typically last up to about a week. Anyone who experiences serious or worsening symptoms should seek medical care.
Prevention
Most people don’t experience any symptoms from Zika virus disease. About 20% of people experience only mild symptoms. However, it is strongly suspected that Zika infections can cause serious complications during pregnancy. Preventing the spread of the infection helps to keep everyone safe. Pregnant women are strongly advised to take strict precautions against exposure to Zika infections. Avoiding mosquito bites and practicing safe sex can limit the spread of the virus form person to person.
There is currently no vaccine for the Zika virus. It will likely take several years to develop an effective vaccine.
Preventing Mosquito Bites
Most cases of Zika virus disease are caused by mosquito bites. This occurs when a person with the virus is bitten by a mosquito, which then transmits the virus when it bites an uninfected person. Therefore, it is strongly recommended to take extra precautions against mosquito bites.
Ways to prevent mosquito bites include:
Whenever possible, stay indoors in a building that has window/door screens or air conditioning.
Wear light-colored, loose-fitting clothing with long pants and long sleeves. The more skin is covered, the less is exposed to mosquitos.
If possible, treat clothing and linens with permethrin. Never use permethrin on skin, it is intended only for use on cloth. Always follow package instructions for use.
Use an insect repellant that contains 25% DEET or has otherwise been certified by an independent agency as effective against mosquitos (for example, repellants registered by the United States Environmental Protection Agency).
Always follow package instructions and re-apply insect repellant regularly.
Apply insect repellant after applying sunscreen.
Avoid putting repellant on open wounds or near the eyes / mouth.
Babies under 3 months of age should not be treated with insect repellant.
When applying insect repellant to small children, spray your hands with the repellant and then rub it onto the child’s skin. Avoid the eyes, mouth, and hands (since young children often put their hands in their mouths).
DEET is safe for pregnant women to use.
Place mosquito netting over cribs and strollers.
Sleep under a mosquito net if living in or traveling to places where there is currently a Zika outbreak.
Remove any sources of stagnant or standing water, such as buckets, pots, tarps, birdbaths, and so on. Mosquitos use water to breed, so removing sources of stagnant water reduces the areas where the mosquitos can multiply.
Help anyone who may need extra attention, such as a young children and older adults.
The mosquitos that spread Zika, chikungunya, yellow fever, and dengue are most active during the mid-morning and from mid-afternoon to twilight (dusk). However, it is a good idea to take precautions around-the-clock.
The virus can be transmitted to another person during the first week of the infection. Anyone who has a Zika infection should take extreme precautions to avoid mosquito bites in order to limit the spread of the infection to others.
Preventing Sexual Transmission
There have been reports of Zika infections being transmitted through sexual contact. The following precautions are recommended in order to prevent sexual transmission of Zika virus disease:
For people who have not had Zika virus disease:
anyone who has lived in or traveled to an area where there is a Zika outbreak should use protection when engaging in oral, anal, or vaginal sex for at least four weeks after leaving the affected area.
For people who have had a Zika infection:
anyone who has had a Zika infection should use protection for at least six months after symptoms have subsided in order to avoid transmitting the infection to others. This is particularly important for women and partners of women who are planning to have children.
It is not yet well understood how common sexual transmission of Zika is. More research is needed to fully understand the risk level.
References
Data Sources
Data from the NHS, CDC, NIH, AHRQ, SEER, Healthcare Bluebook, Videum, and other government and private data sources. All written content is sourced from the NHS and curated by health professionals.
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