About Zika Virus Disease

Zika virus disease

Zika virus disease (Zika) is a disease caused by Zika virus that is spread to people primarily through the bite of an infected Aedes species mosquito. The most common symptoms of Zika are fever, rash, joint pain, and conjunctivitis (red eyes). The illness is usually mild with symptoms lasting for several days to a week after being bitten by an infected mosquito. People usually don’t get sick enough to go to the hospital, and they very rarely die of Zika. For this reason, many people might not realize they have been infected. Once a person has been infected, he or she is likely to be protected from future infections.

Zika virus was first discovered in 1947 and is named after the Zika forest in Uganda. In 1952, the first human cases of Zika were detected and since then, outbreaks of Zika have been reported in tropical Africa, Southeast Asia, and the Pacific Islands. Zika outbreaks have probably occurred in many locations. Before 2007, at least 14 cases of Zika had been documented, although other cases were likely to have occurred and were not reported. Because the symptoms of Zika are similar to those of many other diseases, many cases may not have been recognized.

In May 2015, the Pan American Health Organization (PAHO) issued an alert regarding the first confirmed Zika virus infection in Brazil and on Feb 1, 2016, the World Health Organization (WHO) declared Zika virus a public health emergency of international concern (PHEIC). Local transmission has been reported in many other countries and territories. Zika virus likely will continue to spread to new areas.

Transmission

Zika virus is transmitted to people primarily through the bite of an infected Aedes species mosquito (A. aegypti and A. albopictus). These are the same mosquitoes that spread dengue and chikungunya viruses.

A mother already infected with Zika virus near the time of delivery can pass on the virus to her newborn around the time of birth.

A pregnant woman can pass Zika virus to her fetus during pregnancy. We are studying the adverse pregnancy and infant outcomes associated with Zika virus infection during pregnancy. To date, there are no reports of infants getting Zika virus through breastfeeding. Because of the benefits of breastfeeding, mothers are encouraged to breastfeed even in areas where Zika virus is found.

Zika virus can be spread by a man to his sex partners. In known cases of likely sexual transmission, the men had Zika symptoms, but the virus can be transmitted before, during, and after symptoms develop. In one case, the virus was spread a few days before symptoms developed.The virus is present in semen longer than in blood.

As of February, 1, 2016, there have not been any confirmed blood transfusion transmission cases in the United States. There have been multiple reports of blood transfusion transmission cases in Brazil. These reports are currently being investigated. During the French Polynesian outbreak, 2.8% of blood donors tested positive for Zika and in previous outbreaks, the virus has been found in blood donors.

Symptoms

• Most people infected with Zika virus won’t even know they have the disease because they won’t have symptoms. The most common symptoms of Zika are fever, rash, joint pain, or conjunctivitis (red eyes). Other common symptoms include muscle pain and headache. The incubation period (the time from exposure to symptoms) for Zika virus disease is not known, but is likely to be a few days to a week.
• • See your healthcare provider if you are pregnant and develop a fever, rash, joint pain, or red eyes within 2 weeks after traveling to a place where Zika has been reported. Be sure to tell your health care provider where you traveled.
• The illness is usually mild with symptoms lasting for several days to a week after being bitten by an infected mosquito.
• People usually don’t get sick enough to go to the hospital, and they very rarely die of Zika. For this reason, many people might not realize they have been infected.
• Zika virus usually remains in the blood of an infected person for about a week but it can be found longer in some people.
• Once a person has been infected, he or she is likely to be protected from future infections.

Diagnosis

• The symptoms of Zika are similar to those of dengue and chikungunya, diseases spread through the same mosquitoes that transmit Zika.
• See your healthcare provider if you develop the symptoms described above and have visited an area where Zika is found.
• If you have recently traveled, tell your healthcare provider when and where you traveled.
• Your healthcare provider may order blood tests to look for Zika or other similar viruses like dengue or chikungunya.

Treatment

• There is no vaccine to prevent or medicine to treat Zika infections.
• Treat the symptoms:
  • Get plenty of rest.
  • Drink fluids to prevent dehydration.
  • Take medicine such as acetaminophen (Tylenol®) or paracetamol to relieve fever and pain.
  • Do not take aspirin and other non-steroidal anti-inflammatory drugs.
  • If you are taking medicine for another medical condition, talk to your healthcare provider before taking additional medication.
• If you have Zika, prevent mosquito bites for the first week of your illness.
  • During the first week of infection, Zika virus can be found in the blood and passed from an infected person to a mosquito through mosquito bites.
  • An infected mosquito can then spread the virus to other people.

Gravitational Waves

What are Gravitational Waves?

Gravitational waves are distortions or 'ripples' in the fabric of space-time caused by some of the most violent and energetic processes in the Universe. Albert Einstein predicted the existence of gravitational waves in 1916 in his general theory of relativity. Einstein's mathematics showed that massive accelerating objects (such as neutron stars or black holes orbiting each other) would disrupt space-time in such a way that 'waves' of distorted space would radiate from the source. Furthermore, these ripples would travel at the speed of light through the Universe, carrying with them information about their cataclysmic origins, as well as invaluable clues to the nature of gravity itself.


The strongest gravitational waves are produced by catastrophic events such as colliding black holes, the collapse of stellar cores (supernovae), coalescing neutron stars or white dwarf stars, the slightly wobbly rotation of neutron stars that are not perfect spheres, and the remnants of gravitational radiation created by the birth of the Universe itself.

Though gravitational waves were predicted to exist in 1916, actual proof of their existence wouldn't arrive until 1974, 20 years after Einstein's death. In that year, two astronomers working at the Arecibo Radio Observatory in Puerto Rico discovered a binary pulsar--two extremely dense and heavy stars in orbit around each other. This was exactly the type of system that, according to general relativity, should radiate gravitational waves. Knowing that this discovery could be used to finally test Einstein's audacious prediction, astronomers began measuring how the period of the stars' orbits changed over time. After eight years of observations, it was determined that the stars were getting closer to each other at precisely the rate predicted by general relativity. This system has now been monitored for over 40 years and the observed changes in the orbit agree so well with general relativity, there is no doubt that it is emitting gravitational waves.

Why Detect Them?

The gravitational waves that are detectible by LIGO will be caused by some of the most energetic events in the Universe—colliding black holes, exploding stars, and even the birth of the Universe itself. Detecting and analyzing the information carried by gravitational waves will allow us to observe the Universe in a way never before possible. This will open up a new window of study on the Universe, giving us a deeper understanding of these cataclysmic events, and usher in brand new cutting-edge studies in physics, astronomy, and astrophysics.

Historically, scientists have relied primarily on observations with electromagnetic radiation (visible light, x-rays, radio waves, microwaves, etc.) to learn about and understand objects and phenomena in the Universe. (In recent years, subatomic particles called neutrinos have also been used to study aspects of the heavens.) Each of these sources of information provides scientists with a different and complementary view of the Universe, with exciting new discoveries occurring as each new 'window' has been discovered, introduced, and utilized.

Gravitational waves are not electromagnetic radiation. They are a completely different phenomena, carrying information about cosmic objects and events that is not carried by electromagnetic radiation. Colliding black holes, for example, emit little or no electromagnetic radiation, but the gravitational waves they emit will cause them to "shine brightly" like beacons on an utterly dark cosmic sea. More importantly, since gravitational waves don't interact with matter (unlike electromagnetic radiation), they travel through the Universe completely unimpeded giving us a crystal clear view of the gravitational-wave Universe. They will carry information about their origins that is free of the distortion or alteration suffered by electromagnetic radiation as it travels through millions of light years of intergalactic space. With this completely new way of examining astrophysical objects and phenomena, gravitational waves will truly open a new window on the Universe, providing astronomers and other scientists with their first glimpses of previously unseen and unseeable wonders, and greatly adding to our understanding of the nature of space and time itself.