The new coronavirus has dominated headlines since it was first detected in Wuhan, China, in December, and reported cases continue to climb across the globe.
With concerns heightened about the virus, many people are wondering: How will this coronavirus outbreak end?
There’s still a lot that isn’t known about the new virus, known as COVID-19, but here’s a look at what happened with other infectious disease outbreaks.
The Zika virus is usually mild, with symptoms including fever, rash, conjunctivitis and muscle pain. In rare instances, it can cause complications including nerve damage and brain swelling. An infected expectant woman can pass the virus to her unborn child.
The Zika virus was first recorded in humans in 1952 in Uganda and the United Republic of Tanzania, but there have been outbreaks since. The virus reached the United States in 2015 after an outbreak in Brazil spread to other countries. By 2016, there were more than 5,000 reported cases in the U.S.
The number of reported cases started to decline in 2017, and there were no cases left in the country by 2018, according to the U.S. Centers for Disease Control and Prevention.
Essentially, the disease died off on its own. Experts have said it happened because of herd immunity — as more people became infected and recovered, more people became immune. But it’s still possible for it to come back. Mosquitos known to carry the virus are found in many U.S. states, including Texas, according to the CDC.
The Ebola virus is a deadly disease that causes fever, aches, fatigue, diarrhea and vomiting, unexplained bleeding or bruising, and sometimes a skin rash, according to the CDC.
The virus was first discovered in 1976 in what is now the Democratic Republic of Congo. But there have been occasional outbreaks and reported cases since. An outbreak that began in 2018 is currently ongoing in the Eastern Democratic Republic of the Congo, but has been slowing since February, according to the World Health Organization.
Ebola has special significance in Dallas. In 2014, the United State’s first known case was detected in 42-year-old Thomas Eric Duncan, a Liberian national. Just days after his death in October 2014, two nurses who cared for Duncan at Texas Health Presbyterian Dallas also contracted the disease. They eventually recovered.
The 2014 outbreak was the most widespread and most complex outbreak since the virus was discovered, WHO said. During the 2014 outbreak, 11 people were treated in the United States and two died, according to the CDC. The global outbreak ended in 2016, according to WHO.
Dr. Peter Hotez, professor and dean for the National School of Tropical Medicine at Baylor College of Medicine, told CNN that during both the 2014 and 2018 outbreaks, human intervention helped stop the virus.
The 2014 outbreak was stopped by collaboration between multiple federal agencies that resulted in enhanced travel screenings, safe transport of patients suspected of having Ebola and strengthened emergency preparedness in hospitals, the CDC said on its website. CNN also reported that treatments developed after previous outbreaks have helped slow the 2018 outbreak.
West Nile virus is another disease primarily spread through mosquitoes. According to the CDC, 80% of people who get the disease won’t show any symptoms, while 20% will get symptoms including fever, headache, body aches, vomiting and diarrhea.
But most will likely recover. Less than 1% of people have serious complications, such as nerve damage, brain inflammation or meningitis.
According to WHO, the virus maintains a cycle in nature, infecting birds and mosquitos and sometimes spreading to people. Human cases have been reported every year in the United States since 1999, and there have been about 2,300 cases reported in the U.S. on average since 2013, according to CDC data.
But there was a particularly bad outbreak of the disease in 2012, when more than 5,600 cases were reported. It was the highest number of cases reported in the country since 2003, when almost 10,000 cases occurred in the U.S.
Dallas was hit particularly hard by the 2012 outbreak. Almost half of the more than 1,800 cases reported in Texas were in the Dallas-Fort Worth area, according to a study published by the CDC. Health experts said that winter was warmer than usual in North Texas, helping spread the virus.
The 2012 outbreak was eventually slowed in part by a Dallas cardiologist who advocated for aerial insecticide spraying, D Magazine reported.
H1N1, or Swine flu
In April 2009, a new H1N1 influenza virus emerged, marking the first flu pandemic in 40 years, according to the CDC. The symptoms are the same as the flu and include fever, coughing, sore throat, congestion and body aches. The H1N1 strain is also sometimes referred to as the “swine flu” because it originated from a virus typically seen in pigs.
WHO declared the outbreak a public health emergency the same month it was detected. But by July, more than 1 million people were infected and the CDC stopped keeping an official count of cases.
A vaccine for the virus became available in December 2009, and WHO announced the end of the pandemic in August 2010. The H1N1 virus is now a seasonally occurring human flu virus, peaking in colder months, according to the CDC.
Severe acute respiratory syndrome, or SARS, is another human strain of coronavirus that was identified in 2002 in China. It has symptoms similar to the flu, including fever, chills and diarrhea. It had a death rate of almost 10%.
There were more than 8,000 cases in 26 countries by the time the virus stopped in July 2003. There have not been any known cases of SARS anywhere in the world since 2004, according to the CDC.
Jessica Fairley, a professor of global health medicine at Emory University, told Vox that human interventions, including coordination between public health authorities and healthcare providers and increased travel advisories and screenings, stopped the outbreak.
While SARS can be used to help guide health experts on what to expect with the new coronavirus, it’s important to note that there are significant differences between the two outbreaks.
For one, more cases of the new coronavirus have already been reported than there were of SARS. And unlike SARS, health experts still don’t know for sure if people can spread the new coronavirus when they’re not showing symptoms.
The CDC believes people are most contagious when they’re the most sick. But if people can spread it when they aren’t feeling ill, the disease will be harder to contain because people could be contagious and not know to seek medical care.