Some enemies are stealthy, invisible foes that cannot be fought by direct confrontation; they’re on you before you can react. Viruses would fit into this category. Not very impressive on their own, these microscopic clumps of genetic material wreak havoc on human health quite frequently. Surprisingly, despite the fact that they cannot survive without squatting in a host cell, they have endured for probably 2 billion years, according to the best scientific evidence. They are numerous, to the tune of thousands of types with literally millions of strains, most of which are anonymous without name or characterization.

Despite their longevity in society and some familiar names like flu or chickenpox, it seems that we frequently hear about new viruses or outbreaks, especially of late. Ebola and chikungunya dominated the news for the last 18 months and now, a new viral player has overtaken the headlines: Zika.

While Zika virus has been encountered before in Asia and Africa, it hit the news cycle in the Western Hemisphere in May 2015. Since that time, there have been large numbers of cases contracted in Central America, South America and the Caribbean. Cases have been identified in the U.S. among returning travelers and, most recently, there have been sexually transmitted Zika infections from males to females.

Zika virus is carried by certain types of mosquitoes, which act as a vector to spread the infection. As they bite and feed off humans, they basically inject the virus into the person who essentially hosts the virus as it takes up residence in his or her cells. This allows the virus to reproduce and cause infection. The mosquitoes that carry the infection have not been identified to a great extent in the continental U.S.

As with most viruses, Zika often doesn’t trigger symptoms. In fact, only 1 out of every 5 people infected will show signs of illness. The time it takes to show symptoms after a bite from a mosquito carrying the virus, known as the incubation period, is somewhere between two and 10 days. For those who do get ill, the symptoms are nonspecific and can be seen with many different kinds of infections. Fever, rash, red eyes and aching joints characterize this disease. For most people, the disease will run its course and spontaneously resolve within a few days to weeks.

However, as with all viral illnesses, complications can occur under certain circumstances. A very small number of those who contract symptomatic Zika virus will develop a neurological complication known as Guillain-Barre syndrome, which results in progressive weakness that spreads from the lower extremities upward. This complication can be fairly incapacitating for a period but generally improves over time.

Another serious consequence of Zika infection involves the effects on an unborn baby. If women contract Zika during pregnancy, the virus can affect the fetus, resulting in calcium deposits in the brain tissue and a small head size, also known as microcephaly. Small head size indicates poor brain growth and developmental delay is likely to occur in these babies. Many viruses encountered by the fetus in the womb can result in these same complications. Over the last few years in Brazil, there has been an abrupt and significant increase in babies born with microcephaly, and Zika virus has been identified in some but not all of those cases.

The diagnosis of active Zika virus infection is made by identifying either virus particles in various body fluids, such as blood, semen or amniotic fluid from the uterus. Alternatively, antibodies can be detected, specific bodily responses to the Zika virus. These tests are not widely available but can be accessed through the Centers for Disease Control and Prevention or a few state health departments.

Unfortunately, viruses are generally not very easy to treat. Unlike bacteria, which respond to antibiotics relatively well, viruses pretty much have to run their course. There are a few antiviral medications for a select group of viruses but not for many of the strains, including Zika. Therefore, only supportive treatment is possible with acetaminophen, rest and fluids being the mainstays. Since Zika resembles many other viral illnesses and can be picked up in the same places where infections like dengue or chikungunya are prevalent, aspirin and ibuprofen-type medications should be avoided due to side effects until those causes are ruled out. These viruses can make a person prone to bleeding, and both aspirin and ibuprofen can increase the risk of hemorrhage significantly. But for those babies who have suffered brain deposits of calcium, which essentially act like scars on the brain, and microcephaly, there is no going back. The damage is permanent.