(CNN)All eyes are on Rio de Janeiro and its Zika-carrying mosquitoes as the countdown to the 2016 Olympics continues. Here is the latest on how the battle against the Zika virus is being won or lost and how that effort is affecting athletes, visitors and the success of the Games.
Zika threat worries mothers in Brazil 02:30
August 24, 2016: WHO says no cases of Zika from Olympics so far
"There have so far been no laboratory confirmed cases of Zika virus in anyone associated with the Olympics," the World Health Organization said in a weekly report about the virus. This was the first of these reports issued since the Games ended on August 21.
June 5, 2016: U.S. to study athletes and staff going to Rio for Summer Games
The U.S. National Institutes of Health announced they are funding a study of 1,000 athletes and staff of the US Olympic Committee heading to Rio for the Olympics and Paralympics next month. The study, led by Dr. Carrie Byington, an infectious disease specialist at the University of Utah and head of the USOC Infectious Disease Advisory Group, aims to, "determine the incidence of Zika virus infection, identify potential risk factors for infection, detect where the virus persists in the body (blood, semen, vaginal secretions or saliva), evaluate how long the virus remains in these fluids, and study the reproductive outcomes of Zika-infected participants for up to one year," according to the announcement from NIH. Study participants will have samples taken before they depart and then will be followed after as well. Spouses of USOC staff will also be eligible to participate in the study.
June 14, 2016: The WHO says Olympics will not spread Zika
The World Health Organization again beats back critics calling for the Olympics to be postponed or moved, saying there is "very low risk" the Games will spread the Zika virus.
To back up its decision, the WHO pointed to research predicting that only 1.8 tourists out of a million will get the virus during the Olympics and a study that found that only three foreign visitors out of 600,000 were infected with dengue during the 2014 World Cup in Brazil.
Athletes skipping Olympics because of Zika
South African golfer Lee-Anne Pace
Australian golfer Jason Day
Northern Irish golfer Rory McIlroy
Australian golfer Marc Leishman
Fijian golfer Vijay Singh
British long jumper Greg Rutherford
American cyclist Tejay van Garderen
June 7, 2016: Rio's Olympic organizers fight Zika fears
Using slides that show a dramatic drop in new Zika cases, the organizers for the Rio games fight back against growing criticism. One of their most powerful pieces of data: a study that says the most likely scenario during the 2016 Olympics is that Zika will affect 1.8 people per 1 million tourists. The new health minister for Brazil goes on the record as saying the chance of catching Zika during the Olympics is "almost zero."
June 1, 2016: Chicago Bulls forward Pau Gasol says he may skip the Olympics
Chicago Bulls forward Pau Gasol, who has been planning to play for his native Spain at the Summer Games, tells CNN's Jake Tapper that his decision on whether to attend is "still up in the air." He had previously told reporters that concern over the virus was giving him pause. Gasol told Tapper that his comments were a reaction to a lack of information about the the virus, especially in Spain, and that he wanted to raise awareness so individuals can make informed decisions.
May 27, 2016: Prominent doctors and professors tell WHO to postpone or move the games
A group of more than 100 prominent doctors and professors signs a letter submitted to WHO Director-General Margaret Chan, saying the Summer Games should be postponed or moved "in the name of public health." The letter makes the case that with the outbreak in the Rio area worsening and previously unknown medical consequences of the virus coming to light, it is "unethical to run the risk" of infection
May 26, 2016: CDC director says no reason to move or delay games
Dr. Tom Frieden, director of the U.S. Centers for Disease Control and Prevention, says, "There is no public health reason to cancel or delay the Olympics."
Frieden did say the risk is not zero for those traveling for the Olympics. Olympic-related travel represents just 0.25% of the total 40 million travelers between the U.S. and countries where the Zika virus is circulating, according to the CDC.
May 19, 2016: USA Swimming moves training out of Puerto Rico
USA Swimming informs its coaches and athletes of the relocation of a pre-Olympic training camp from Puerto Rico to Atlanta because of "the current situation with the Zika virus." Director Frank Busch sends a letter the team informing them of the change of plans for the second camp to be held in the days leading up to the group's departure for the Summer Games in Rio. "According to the CDC (Centers for Disease Control and Prevention) and other health experts in the field of science and medicine, our athletes would be highly exposed to the Zika virus in Puerto Rico," the letter said, adding that the health and safety of team members is the priority. Busch also says the team will be providing athletes and coaches with tools to reduce the risk of mosquito bites while they are in Rio.
May 16, 2016: Australian Olympians will get 'Zika-proof' condoms
Australia's Olympic team will receive so-called Zika-proof condoms, lubricated with a "potent antiviral against Zika," according to manufacturer Starpharma Holdings Ltd. However, the manufacturer's website says it has not applied for or received regulatory approval for its claim.
May 12, 2016: WHO attempts to calm Olympic fears over Zika
Reacting to the growing concerns from athletes and visitors to the Games, the World Health Organization puts out a statement addressing those fears.
On the same day, the Brazilian Senate votes 55-22 to remove Dilma Rousseff as President and move forward with impeachment, further sidetracking the country's fight against Zika. However, the International Olympic Committee says the political crisis should not affect the Games.
Rousseff tells CNN's Christiane Amanpour that she will be "very sad" if she misses the Olympics.
May 6, 2016: Olympic Games 'must not proceed'
Harvard's Public Health Review publishes a commentary by a Canadian professor, Amir Attaran, who states his "bitter truth": Both the Olympic and Paralympic Games must be postponed, moved or both. "But for the games, would anyone recommend sending an extra half a million visitors into Brazil right now?"
April 29, 2016: South Korea unveils anti-Zika uniform
National teams start to show off their Olympic finery. South Korea even made sure its uniform was Zika-proof.
April 27, 2016: 100 days to go
The countdown is on for the last 100 days until the Games begin on August 5. Is the city ready?
April 18, 2016: Brazilian House votes to impeach President Dilma Rousseff
Suspended Brazilian President Dilma Rousseff speaks to supporters
More than two-thirds of the lower house of the Brazilian government votes to impeach President Dilma Rousseff over charges of corruption. Rousseff vows to fight, but worry erupts over the impact on the preparation for the Olympic Games.
April 8, 2016: Ticket sales slow; is Zika to blame?
With only four months to go, organizers announce that only half of the tickets for the August Games are sold but that they are optimistic for the success of the Games because most hotels are fully booked.
March 4, 2016: U.S. Olympic Committee creates Zika panel
The U.S. Olympic Committee announces that it will create a three-doctor advisory panel that will answer Olympians' questions and publish recommendations to help keep U.S. team members and staff from becoming infected with Zika during the Games.
An Aedes aegypti mosquito, which can carry the Zika virus.
February 29, 2016: Olympians must pay for screens to block mosquitoes
The organizing committee for the Games announces that it will install screens to block mosquitoes in communal areas "where required" but will charge national delegations to have the screens placed on athletes' rooms.
February 26, 2016: CDC to pregnant women: Don't go
The CDC hardens its advisory on travel, telling pregnant women or those trying to become pregnant not to travel to any of the countries where Zika is circulating, including the Olympic Games and the Paralympic Games.
U.S. soccer player Hope Solo eventually decided to attend the Games.
February 9, 2016: Soccer star Hope Solo says 'I wouldn't go'
U.S. women's national soccer team goalkeeper Hope Solo says "If I had to make the choice today, I wouldn't go" to the Olympics because of her fears about the Zika virus. By May, she announces that she will go but will spend any free time in her hotel room, away from mosquitoes.
February 1, 2016: WHO declares Zika a 'public health emergency'
After warning that Zika was "spreading explosively" thoughout the Americas, with as many as 3 million to 4 million infections expected in the next year, the World Health Organization declares Zika a "public health emergency of international concern."
January 29, 2016: IOC releases statement on Zika
Everything you need to know about Zika 01:42
The International Olympic Committee releases a statement on Zika that tries to address growing concern about the site for the 2016 Summer Games. The statement stresses actions on the part of the Brazilian government to combat the threat and says a plan is in place to inspect standing water, where mosquitoes breed, on a daily basis. Just what is the health threat facing Olympians?
January 15, 2016: CDC warns pregnant women to think twice
The CDC advises all pregnant women or those trying to become pregnant to avoid travel to any of the countries where Zika is active, including Brazil during the Games.
November 11, 2015: Public health emergency declared
Brazil declares a national public health emergency as numbers of infants born with microcephaly continue to rise.
October 30, 2015: Brazil reports unusual number of birth defects
A number of Brazilian babies are being born with microcephaly.
Nine months after the first cases of Zika, women begin to give birth to babies with an unusual birth defect, microcephaly, in which the baby's head and brain do not develop properly.
February 2015: Brazil sees first cases of Zika but doesn't know what it is
From February through April, Brazil sees 7,000 cases of a mild viral reaction characterized by rash, fever and red eyes. Zika isn't identified in the blood samples until May. By July 2015, doctors begin seeing a few cases of Guillain-Barré Syndrome.
October 2009: Rio chosen as site of the 2016 Summer Games
Rio de Janeiro is chosen to host the 2016 Summer Olympics, the first South American city to do so. As Brazilians celebrate, there's no sign of Zika, a little-known disease that's mostly confined to Africa and Asia.
