The Zika virus is making headlines now as alarm over it spreads through South and Central America and the United States. Currently, there is no vaccine to prevent infection or medicine to treat Zika, which is contracted through a mosquito bite. It has been linked to babies born with brain abnormalities, including microcephaly, according to the Centers for Disease Control and Prevention. President Barack Obama has called for rapid research into a vaccine for the virus. Zika is the latest health scare, but it wasn't so long ago that polio, Ebola and mad cow disease caused similar alarm. Here's a look back at some of the biggest and scariest outbreaks in the United States and abroad.
The disease caused by the Ebola virus is severe, fast moving and most often fatal in humans. It can be transmitted to humans from wild animals, and also from human-to-human contact. It first appeared in 1976 near the Ebola River in two simultaneous outbreaks, one in what is now, Nzara, South Sudan, and the other in Yambuku, Democratic Republic of Congo, according to the World Health Organization. The epidemic that began in West Africa in early 2014 is the largest in history, affecting multiple countries in that region, according to the U.S. Centers for Disease Control and Prevention. In the fall of 2014, four people in the United States tested positive for Ebola after traveling into affected countries. Three of the patients recovered but one died in Texas. Worldwide, there have been 28,639 cases and 11,316 deaths, as of Feb. 14, 2016, according to the WHO. Earlier in the year, the agency had declared that for the first time in two years, Guinea, Liberia and Sierra Leone were all Ebola-free, but shortly after that the latter experienced a small flare-up. Pictured: A child stands near a sign advising of a quarantined home on Oct. 22, 2014, an effort to combat the spread of the Ebola virus in Port Loko, Sierra Leone.
Swine flu, also known as H1N1 flu, caused a worldwide pandemic in 2009. Between April, when the first case was detected in a 10-year-old California boy, and mid-November of that year, one in six Americans had caught the new flu virus, and about 10,000 died, the CDC estimates. Almost immediately, the CDC began developing a vaccine and President Barack Obama declared a national emergency. The global pandemic officially ended the following summer. The H1N1 viruses and seasonal influenza viruses still circulate in many parts of the world, according to the CDC, which says it is likely that H1N1 will spread for years to come like a regular seasonal influenza virus. Pictured: Michael Hartman, 10, comforts his pregnant mother, Julie Hartman-Pellerito, of Plandome while she gets vaccinated for swine flu on Nov. 16, 2009, at the Nassau County Health Department in Uniondale.
Severe Acute Respiratory Syndrome, better known as SARS, was first identified in February 2003 in China, though the first case is believed to have occurred four months prior. In the spring of 2003, the World Health Organization issued a global health alert for SARS as it became clear the disease was being spread by global air travel. Between November 2002 and July 2003, 8,098 people worldwide had become sick including 774 who died, according to the WHO. Pictured: A lone Western visitor wearing a surgical mask to protect himself reads a book in a nearly empty Air China flight from Hong Kong to Beijing on June 5, 2003.
Mad cow disease
Mad cow disease, also known as bovine spongiform encephalopathy, strikes the nervous system of cattle and is fatal. It was first detected in the 1970s, but in the 1990s the United Kingdom experienced an outbreak. At its peak, there were almost 1,000 new cases per week with 14,562 cases in 1995 alone. By 2000, that annual figure had dropped to 1,443. The infectious agent that causes the disease in cattle can be transmitted to humans through consumption of contaminated meat causing a variant known as Creuzfeldt-Jakob disease, which was first diagnosed in 1996, according to the European Food Safety Authority. Since then, only 227 patients with this disease have been reported worldwide, the CDC says. Pictured: A herd of calves at a farm in the eastern Bavaria in southern Germany on Dec. 20, 2000. The following January, the government announced it would slaughter an estimated 400,000 cattle in an attempt to curb mad cow disease.
West Nile virus
West Nile virus, which is most commonly transmitted to humans by mosquitoes, can cause febrile illness, inflammation of the brain or meningitis. It was first detected in New York in 1999. That year, there were 62 cases including seven deaths, all within the state, but by 2000, there were outbreaks in New Jersey and Connecticut. Since then, it's been detected throughout the continental United States, according to the CDC. An outbreak occurred between 2002 and 2003 when there were 153 cases including 16 deaths reported in New York alone and about 14,000 cases and 548 deaths across the country. Pictured: A helicopter sits on the ground on Aug. 26, 2002, waiting to take off and spray the pesticide Scourge to kill mosquitoes and help prevent the spread of the West Nile virus in Bay Shore.
The first cases of what was later called AIDS were reported in the United States in 1981, and by 1991 there were more than 206,500 cases reported around the country and about 156,000 deaths, according to the Foundation for AIDS Research. After peaking in the early 1990s, AIDS cases in the United States declined, but it remains a major global public health issue. In 2014, a United Nations report estimated that 36.9 million people worldwide were living with HIV, or human immunodeficiency virus, which can lead to AIDS, including 2.6 million children, and each year about 50,000 Americans get infected. There is no cure for HIV, but with proper medical treatment, the virus can now be controlled, the CDC says. Pictured: The Los Angeles Lakers' Earvin "Magic" Johnson stunned the world when he revealed during a 1991 news conference that he was retiring from basketball because he had tested positive for HIV. He has been living with it for about 25 years.
Legionnaires' disease, a respiratory disease caused by a type of bacteria called Legionella, was first discovered in 1976 among people who attended a Philadelphia convention of the American Legion. There were 221 cases, including 34 deaths, according to The New York Times. Each year, it is estimated that between 8,000 and 18,000 people in the United States need care in a hospital due to Legionnaires' disease. In 2015, an outbreak of the disease in the Bronx led to 12 deaths and sickened about 120 other people. Pictured: American Legion members attend a consumer protection subcommittee hearing on Legionnaires' Disease on Nov. 23, 1976, in Philadelphia.
Smallpox is a serious, contagious, and sometimes fatal infectious disease that's also known for causing raised bumps on an infected person's face and body. It's unclear when and where smallpox originated, but ancient medical texts dating back to 1500 BCE describe a smallpox-like illness, and some estimates indicate 20th-century worldwide deaths from smallpox numbered more than 300 million, according to the College of Physicians of Philadelphia. Smallpox outbreaks have occurred from time to time for thousands of years including an 1875 outbreak that killed 2,000 New Yorkers. In March 1947, a New York City man died of smallpox after returning from a trip to Mexico City, prompting city officials and public health authorities to urge all New Yorkers to get the vaccine. More than 6.3 million New Yorkers were inoculated in less than a month in a successful campaign to contain the outbreak. Smallpox vaccination clinics were set up throughout Nassau and Suffolk for mass inoculations, including school children and commuters to New York City. As of 1980, the disease is considered eradicated, according to the CDC. Pictured: On April 14, 1947, people stood in line waiting to be inoculated against smallpox at the Morrisania Hospital in the Bronx.
Polio is a crippling and potentially deadly infectious disease caused by the poliovirus that can invade an infected person's brain and spinal cord, causing paralysis, the CDC says. It remained relatively uncommon for most the 1800s, but reached epidemic proportions in the early 1900s in countries with relatively high standards of living including the United States. From the late 1940s to the early 1950s, polio outbreaks in the United States increased in frequency and size, with the virus crippling about 35,000 Americans annually. Parents were afraid to let their children go outside to play, especially during the summer months when outbreaks were more common. The number of cases in the country peaked in 1952 with 58,000. That year, Dr. Jonas Salk developed a vaccine and began the first mass inoculation of schoolchildren in Pittsburgh, Pa. Because of widespread vaccination, polio was eliminated from the Western Hemisphere in 1994, according to the CDC. Around the world, it continues to circulate in a handful of countries, the CDC says. Pictured: Martha Prime, 9, of Huntington, puts on a brave face as she gets a polio vaccination on April 27, 1954, from Dr. Joseph Palmieri at the Village Green School in Huntington.
Spanish flu pandemic
The Spanish flu pandemic, considered the mother of all recorded pandemics, infected an estimated 500 million people worldwide, causing 50 million deaths between 1918 and 1919, according to the CDC. It was first observed in Europe and quickly spreading around the globe with Spain being among the first countries to be hit the hardest. In the United States, it came in three waves, and killed an estimated 675,000 Americans, including 43,000 U.S. servicemen. The influenza was most deadly in healthy adults, ages 20 to 40. During the fall of 1918, researchers began developing a range of vaccines, but none proved effective. Meanwhile, politicians and physicians came to believe that the spread of the disease could be contained by quarantines, forcing people to wear masks, banning spitting in public, shutting down schools and theaters and forbidding large gatherings. But these efforts did little to curtail the pandemic, which didn't end until mid-1919 when those who had been infected had either died or developed immunity, according to the CDC. Pictured: Influenza victims are quarantined in 1918 in Camp Funston, an emergency hospital at Fort Riley, Kansas.