Zika virus causes the infectious disease known as Zika or Zika virus disease. In this article, we will review all the essentials of it.
The number of global cases of Zika infection can’t be confirmed. This is because Zika often causes no symptoms and can be mistaken for other diseases. As of July 2019, a total of 87 countries have had cases and transmission of the Zika virus. They may be more since there are thought to be countries with cases that haven’t been detected or reported.
In the American continent, Zika outbreaks peaked during 2016 and quickly declined during 2017 and 2018. During 2016, around 650.000 Zika cases were detected in America alone. By 2018, in the same continent, the number of cases dropped to 31.000 cases.
In the following article, you will find all you need to know about Zika. A doctor will briefly explain all your frequently asked questions. Where did Zika come from, what are its symptoms, and how can you prevent it. You will also find the answers to more complicated questions like how is Zika diagnosed and what are its complications. All of this, in simple words. So, keep reading, so you will learn everything you should know about this infectious disease.
Is Zika a virus or a bacteria?
First of all, Zika is a virus, not a bacteria. This can be confusing since they are both microscopic beings that cause disease. Viruses and bacteria are different in many ways, from their structure to the way they reproduce. Relax; you don’t need to know the differences between bacteria and viruses to understand Zika infection. All you need to know is that Zika is a virus that can be transmitted through mosquito bites. In fact, the Zika virus is from the same family of viruses of Dengue virus and yellow fever virus.
What is the Zika virus?
Zika, or Zika virus disease, is an infectious disease caused by the Zika virus. It is transmitted mostly from an infected mosquito bite. The mosquito species responsible for transmitting Zika is the Aedes species (like Aedes aegypti and Aedes albopictus). These mosquitoes are more likely to bite during the day, but they can bite at night, too. They can also live inside your house or in nearby areas, making them more likely to bite. Humans, primates, and mosquitoes are the main carriers of this virus.
In most cases, Zika infection causes mild illness and can go unnoticed around 80% of the time. The incubation period, which is the time it takes for symptoms to appear after getting the infection, can take from 3 to 12 days, but when symptoms appear, they usually last less than seven days. Zika has unspecific symptoms like fever, rash, headache, or pain behind your eyes. It rarely causes complications, but it has a link with Guillain-Barré syndrome and abnormalities at birth.
Zika virus was first identified in Uganda in 1947. After that, many outbreaks of the disease took place throughout recent history.
Where did the Zika virus come from?
Zika virus was first in a species of monkeys (rhesus monkeys) in a region of Uganda around 1947. In fact, Zika gets its name from the Zika forest in Uganda, where it appeared for the first time. Later,
Zika was identified in humans around 1952 in Uganda and Tanzania. After this, public health authorities detected sporadic cases across Africa and Asia around the 1960s to 1980s. It was until 2007 when the first Zika outbreak occurred in the islands of Yap (Micronesia). Then, other outbreaks followed in French Polinesia and other countries in the Pacific in 2013. Eventually, in 2015, Brazil reported cases of Zika virus that became a large outbreak. Shortly after, evidence of outbreaks and transmission appeared in America, Africa, and other world regions. The global number of Zika cases reached its peak in 2016. To this day, around 86 countries have reported evidence of Zika infection.
How is the Zika virus spread?
The first thing you need to know is that humans are the main reservoir for the virus. This means that the virus lives within the human, replicating itself for a specific time. An Aedes mosquito bites the infected person and sucks blood with Zika virus in it, becoming infected. Later, the infected Aedes mosquito bites another human and introduces the virus in the person’s bloodstream. This is called a human-to-vector-to-human transmission and is the most important way in which Zika spreads. In fact, this is the mechanism that causes outbreaks in a determined population.
There are also other ways in which Zika can spread, but they are less common. Zika virus can penetrate through the placenta to infect babies in a pregnant woman’s uterus. Also, infected pregnant women can pass the infection at the moment of birth. This is important because the Zika virus can be the cause of congenital disabilities.
Moreover, another form of Zika transmission includes sexual transmission. Even patients who didn’t experience any symptoms of the disease can spread Zika through sexual contact. The same thing happens with blood donations. Blood donors can have the infection without experiencing symptoms and can transmit it through blood transfusions. However, these types of transmission are only common during Zika virus outbreaks.
What are the roles of other animals in Zika virus transmission?
The role of other animals in Zika transmission is variable. For example, primates such as monkeys can become infected with Zika if bitten by an infected mosquito. They can also act as a reservoir of the virus. This means that a mosquito can get infected after biting an infected monkey and continue the Zika virus transmission.
There are not any reports of pets or other animals becoming sick with the Zika virus. Also, current studies suggest that other animals can’t spread Zika. The infection can also not be transmitted to people from direct contact with animals like touching or licking. A study done in the 1970s showed that other animals like horses, cows, and goats could have the Zika virus. However, they don’t become sick or transmit Zika to other animals or humans.
Who is at risk of Zika infection?
People who are at risk of developing Zika infection include the following:
- People who live or travel to areas with Zika outbreaks: These areas include most tropical and subtropical regions. If you travel to these regions, keep in mind that you should avoid mosquito bites as much as you can. You can do this by using repellent, long sleeves shirts and pants, and a mosquito net. Mosquitoes that transmit Zika can be found anywhere in the world. However, areas with a higher mosquito population have a higher risk of Zika outbreaks.
- Having sex with a person at risk or with Zika infection: Zika can also transmit through sex. This is why the CDC (Center for Disease Control) recommends using a condom or avoid sex. You should do this if you or your partner traveled to areas with Zika outbreaks. It also includes pregnant women who have traveled or have a partner that traveled to these areas.
- People who have stagnant water in their homes or nearby: Aside from living in a country with Zika outbreaks, the chances of Zika increase for these people. This happens because mosquitoes use stagnant waters to place their eggs and reproduce. This results in more mosquitoes around your home that can have the virus.
What countries have the Zika virus?
Sometimes, it isn’t easy to know how many Zika cases exist in a country. This is because the infection can be asymptomatic, or it can be mistaken with other diseases. However, it is obvious that those countries with a higher Aedes mosquito population have a higher chance of more Zika cases. Regions of the Caribbean, Latin America, and the Pacific are the ones with active Zika virus infection right now. Some of these countries include:
- Caribbean: Aruba, Barbados, Curacao, Cuba, Dominican Republic, Haiti, Jamaica, Saint Martin, Trinidad and Tobago, and Puerto Rico (US territory).
- Latin America: Bolivia, Brazil, Colombia, Costa Rica, Ecuador, El Salvador, Guatemala, Honduras, Nicaragua, Mexico, Panama, and Venezuela.
- Pacific: Fiji, Micronesia, Tonga, Samoa, among others.
In the US, Zika is a notifiable disease. This means that doctors are obligated to report suspected Zika infection cases to reduce local transmission and prevent outbreaks. In order to see the areas with outbreaks, current or past Zika transmission, click here.
What are the symptoms of the Zika virus?
Most of the time, Zika virus infection will cause mild symptoms that get better on their own. The incubation period can last from 3 to 12 days from the possible exposure. Zika causes a mild illness or shows no symptoms; therefore, it can go unnoticed in around 80% of cases. Also, it can be mistaken for other viral infections like the dengue virus.
One of the most characteristic symptoms of Zika is the rash. In fact, the rash can be a significant clue to rule out other conditions that can be mistaken for Zika. The rash is mostly fine, with tiny red spots and papules (little bumps), and its distribution is usually diffuse. It can affect the face, trunk and arms, and legs, including palms and soles. In some cases, the rash can also itch. The rash and other symptoms usually appear in the first week of the disease and can last for days.
Additional to the rash, Zika symptoms include the following:
- Joint pain (it can even affect the joints of the hands and feet)
- Retroocular pain (pain behind your eyes).
- Conjunctivitis (Pink eye).
Even without treatment, all of these symptoms resolve on their own. Zika rarely causes any complications. However, it can happen, and we will discuss them later on.
Which is the difference between Zika, Dengue, and Chikungunya?
The main difference between these three conditions is that they’re all caused by a different virus. Zika virus, Dengue virus, and Chikungunya virus are all different viruses that are different in structure and composition. However, it is common that these diseases are often mistaken for one another. This is since they are all transmitted by infected Aedes species mosquitoes and cause similar symptoms. We’ll be focusing on the clinical manifestations to differentiate these diseases.
- Fever: The three of them can cause fever. However, one of the most important characteristics of Dengue is the high fever, compared to Zika and Chikungunya.
- Muscle and joint pain: Dengue and Chikungunya are more likely to cause muscle pain. On the other side, Zika only causes joint pain. And in Chikungunya, the joint pain is severer than in the other two.
- Rash: The three of them can cause a rash. However, it is much more common in Zika than in Dengue or Chikungunya.
- Retro-orbital pain: Pain behind your eyes can be present in the three infections.
- Conjunctivitis: it’s another important characteristic of Zika and Chikungunya which Dengue doesn’t have.
- Liver enlargement: Also known as hepatomegaly. It is an important manifestation of Chikungunya that is not present in Dengue nor Zika.
- Bleeding: It is only present in Dengue and is one of the most dreaded complications of the disease.
What conditions can be mistaken for Zika?
Most of the time, Zika’s signs and symptoms can be very unspecific. It can mimic other conditions and result in a diagnostic challenge for doctors. Some differential diagnosis of Zika infection are:
- Dengue fever: It’s the most serious of these conditions and can be life-threatening
- Chikungunya virus
- Yellow fever
- West Nile virus
How dangerous is the Zika virus?
As we mentioned before, most cases of Zika are mild and self-limited. It may even go unnoticed since it can even happen as an asymptomatic infection. So, most of the time, the Zika virus is not dangerous at all. However, complications have been reported in rare cases. These complications include:
- Guillain-Barré syndrome: It’s a neurologic condition that affects the nerves that result in weakness and diminished reflexes. It can result in symptoms like facial droop, difficulty to speak, swallow, and breathing. Other dangerous symptoms include changes in the heart rhythm (bradycardia or tachycardia), hypertension or hypotension, and urinary retention. If it progresses, it can cause paralysis and result in death because of the respiratory muscles’ paralysis.
- Congenital malformations: Also known as congenital Zika syndrome, it can cause several malformations. Zika virus can pass through the placenta and affect the baby of an infected pregnant mother. This is associated with a higher risk of being born with some malformation. The most common malformation associated with the Zika virus is microcephaly. In microcephaly, the baby’s head’s diameter is reduced, compromising its structures, like the brain. This results in intellectual problems, hearing problems, and slow development. Another common complication of Zika infection during pregnancy are vision problems due to retina abnormalities. Aside from congenital malformations, Zika can also cause preterm birth and fetal death.
How is the infection diagnosed?
If you think you are experiencing Zika symptoms, you should go to the doctor. As we said before, symptoms are usually very mild, and you may not think you need to go to the doctor. However, Zika cases must be notified to public health authorities to prevent further transmission.
Your doctor will ask questions about your medical history and the symptoms you have experienced. Some important questions include asking if you’ve been to a Zika affected area and if you suffered mosquito bites. Then, they’ll perform a physical examination looking for important findings that can help with the diagnosis.
Usually, a clinical diagnosis of Zika can take place. Nevertheless, your doctor will indicate some tests in order to make sure it’s Zika instead of Dengue or Chikungunya. The definite diagnosis of Zika is through serum tests and, most recently, urine tests. Serum and urine tests can determine the presence of the virus in the organism. In fact, studies have shown that the virus lasts more in urine samples than in serum samples, helping the diagnosis. In the serum, doctors can find either the virus itself or antibodies for the Zika virus, indicating that you were infected.
Imaging studies are not useful in the diagnosis of Zika. However, they are widely recommended to pregnant women with suspected Zika infection. Fetal ultrasonography can help detect microcephaly and other possible malformations. There is a procedure called amniocentesis, in which doctors take out amniotic fluid to study it. Amniocentesis can determine the presence of Zika virus within the womb and possible infection.
What is the treatment for Zika virus disease?
There is no specific treatment for Zika virus disease. Doctors recommend supportive care treatment, including rest and gentle fluid hydration. For symptoms like fever and pain, you can take acetaminophen. Other non-steroid anti-inflammatory drugs are not recommended. This is because Zika can be very similar to Dengue fever. In Dengue fever, the risk of bleeding is increased by this type of drug. Aside from this, Zika will get better on its own, and it will not cause you a lot of trouble.
In the event of complications like Guillain-Barré syndrome or congenital malformations, the treatment is different. You may need to attend to a specialist in neurology or maternal-fetal medicine for help.
How can I protect myself from the Zika virus?
Currently, there is not a Zika vaccine available to prevent the disease. Basically, the best method to avoid getting Zika virus is avoiding areas of active Zika virus transmission.
The key to Zika prevention is mosquito control and prevention of mosquito bites. Different strategies for this include:
- Wearing long-sleeved shirts and long pants.
- Sleeping under a mosquito bed net.
- Treating clothes with mosquito repellent.
- Staying inside during the hours of higher mosquito activity and having the air-conditioned facility protect yourself from bites.
Another way to prevent Zika is to stop mosquitoes from reproducing. This can be done with simple measures. Please take into account that mosquitoes place their eggs in stagnant water. Here, their eggs will hatch, and larva will grow. With appropriate handling of waters, a lot can be prevented. This includes discarding or covering water that mosquitoes can use to reproduce. Even if you get Zika, you should avoid getting bitten by mosquitoes. Remember that mosquitoes become infected when they bite an infected person. By avoiding bites while you have the disease, you stop the transmission of Zika.
Other preventive measures respond to other ways of transmission. Since Zika can also be sexually transmitted, it is a formal recommendation that sexual partners use condoms. Especially if they live in a Zika affected area or the woman is pregnant. Women should wait at least eight weeks before attempting to get pregnant. This applies if they had the disease or even a possible Zika exposure. Also, pregnant women are advised to avoid traveling to areas with ongoing Zika virus transmission.
Do you have symptoms of this infection, or were you at risk of it?
This tool is a Zika Virus Symptoms Checker. It gathers the most important signs, symptoms, and risk factors for the infection. Therefore, the tool will tell anybody who uses it the likelihood of their symptoms because of the Zika virus. The tool will also tell if anyone is at risk of having this infection.