Ever since its massive outbreak in Brazil in 2015, which has affected more than one million people, the mosquito-borne Zika virus has seemingly come out of nowhere and caused the World Health Organization (WHO) to declare it a public health emergency on Feb.1, according to Vox. But where did this virus come from and what do we know about it?

When was it discovered?

The Zika virus is actually fairly old. It was discovered in 1947 after it spread from monkeys in Uganda's Zika forest, although for the decades leading to today, it did not cause much harm. In fact, prior to 2007, there were only 14 documented cases of the Zika virus affecting humans.

How does it spread?

Zika is typically carried by the Aedes aegypti mosquito, which spreads it through biting. However, there is also some evidence that points to the Asian tiger mosquito, Aedes albopictus, as being able to carry and transmit the virus, which is worrying due to the fact that this particular species has a range that covers at least 32 states in the U.S.

What are the symptoms?

In the majority of cases, no symptoms are shown in those affected with the virus. Approximately 20 percent of patients show minor symptoms such as sore bodies, a low-grade fever, red eyes and a body rash. However, in rare instances, some people contract Guillain-Barré, a neurological condition that leads to nerve cell damage. Additionally, some pregnant women have children with a birth defect called microcephaly, which leads to stunted brain development in the child.

Does Zika cause microcephaly?

Currently, scientists believe that pregnant women with Zika pass the virus to their unborn babies through the placenta, leading to inhibited brain development. Centers for Disease Control and Prevention (CDC) labs have conducted tests that revealed the virus in the placentas of two miscarried fetuses with microcephaly as well as in the brains of two full-term babies with microcephaly that eventually died.

How dangerous is it?

There is no evidence that Zika causes death and even its connection to Guillain-Barré and microcephaly, as mentioned above, are just correlational - no experimental studies have revealed a direct relationship between the Zika virus and these two conditions, according to The Economic Times. However, some deaths have been reported in patients that already possessed pre-existing medical conditions.

How can I protect myself?

With no vaccine for Zika as of yet, all you can do to protect yourself is avoid mosquito bites using mosquito repellent containing DEET and other common ingredients that are meant to provide long lasting protection. Wear long-sleeved clothing as much as possible and remove things like flower pots, tires and toys from the outdoor areas around your home, as they may harbor pockets of water prime for mosquito dwelling.

How can pregnant women protect themselves?

The CDC has warned pregnant women to avoid travelling to 24 countries and territories where risk is the highest - most areas are located in Central and South America as well as the Caribbean. The risk is highest for pregnant women in their first trimester when brain development is still very fragile, although those in the second trimester are at risk as well. The CDC recommends that pregnant women planning to travel around any of these areas consult with their doctor prior to the trip.

Is there a cure?

Currently, there is no cure for the Zika virus, mainly due to the fact that it did not pose any significant threats to human health until recently. Due to this, research on the virus has been very limited, although some scientists are pointing to genetically modified mosquitos as a fast solution that will eliminate the need to wait for a vaccine to be created. Creating a vaccine will likely take years.

Why Aedes aegypti?

The Aedes aegypti is a very effective mosquito species for carrying viruses, as evidenced by the fact that it is the primary carrier of the yellow fever, dengue and chikungunya viruses. Furthermore, they can live alongside humans with ease by breeding and making their home in the small bodies of water and moist environments common around residential homes such as tree cavities and animal drinking pans.

What are the chances it will spread to the United States?

Despite the fairly wide range of the Aedes aegypti mosquito in the U.S., the outbreaks of the other viruses that it carries, such as dengue and chikungunya, have been very limited, which suggests that the Zika virus will likely not spread either. High sanitation levels, effective air conditioning and window and door screens are all things that are more common in the U.S. than affected countries, so U.S. residents likely have nothing to worry about.