Long before St. Louis encephalitis, West Nile, chikungunya and Zika, another mosquito-transmitted viral disease terrorized the Houston area like none since.

The disease was yellow fever and the time was the 19th century, when medical science was still primitive. The mystery disease struck with ferocity, killing more than a tenth of the population, sickening many more and generally spreading panic among a populace at a loss for how to respond to what seemed an invisible foe.

"The unknown cause, lack of any effective treatment, randomness of who it struck, and awful demise of its victims created a great and perhaps unmatched sense of dread and anxiety in our city's history," said Bryant Boutwell, a medical historian and professor of medicine at the University of Texas Health Science Center at Houston.

Such dread and anxiety occurred again and again in Galveston and Houston, before the disease tapered after 1870. Between 1839 and 1867, the two most devastating years, nine outbreaks gripped the area during mosquito seasons, each a season of terror. Sometimes deaths came so fast that corpses were deposited in long trenches at the old Houston cemetery, buried without a ceremony.

The disease, first reported in American colonies in 1693, mostly was spread to Southern ports by cargo ships carrying slaves from the Caribbean and Africa, where the disease originated. Female Aedes aegypti mosquitoes carrying the virus would nest in cotton bales on the ships and infect passengers, who would unknowingly spread the infection to native species in the U.S. when bitten.

More Information Yellow fever facts Transmission: Virus passed on by bite of female Aedes aegypti mosquitoes Mortality rate: 15 to 20 percent Initial symptoms: Fever, chills, headache, muscle pain Fatal symptoms: Jaundice, black vomit, bleeding Prevention: Vaccine developed in 1937 Source: Chronicle research Houston's 19th century yellow fever deaths Deaths Population percentage 1839 240 12 1867 492 7

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After initial symptoms of fever, chills, headache, dizziness, nausea and muscle pain, four out of five bite victims recovered, with lifelong immunity. For many others, the disease would take a hellish toxic course - fever soared, skin jaundiced as the liver ceased to function normally and internal bleeding in the digestive tract caused bloody vomit.

Author Cotton Mather once described it as "turning yellow, then vomiting and bleeding every way."

The discoloration from jaundice gave yellow fever its name, but it also went by a few others - bronze John, black vomit, American Plague, saffron scourge and yellow jack. The latter nickname came from yellow flags ships were supposed to fly if someone on board was suspected to be infected with yellow fever.

'Sickness, sickness'

Houston's first outbreak, three years after its 1836 birth as the republic's capital, claimed 240 lives over four months, or 12 percent of its population of 2,000 at the time.

"Sickness, sickness, sickness all around and many deaths," reads a diary entry in Marguerite Johnston's "Houston: The Unknown City, 1836-1946." "There are a fearful number of new graves. This was the sixth today. This is an awful disease and does not seem to be understood by the physicians."

It was not. Before mosquitoes were proven to be the culprit, yellow fever was blamed on "miasma," vapors thought to poison the air in many infectious diseases, including cholera and the plague. In response, Houstonians embarked on sanitation efforts that included burning barrels of tar and sulphur in an attempt to neutralize the vapor.

The outbreak also reduced socialization, Boutwell noted. Fearful the disease was contagious, people fled the city, stopped shaking hands, crossed streets to avoid friends or acquaintances, even abandoned sick children. Businesses came to a standstill. Austin was chosen over Houston as the new capital.

Houston's Dr. Ashbel Smith, who in 1883 would go on to become the first chairman of the new University of Texas in Austin, sought to prove the disease wasn't contagious, going so far as to taste the vomit of some terminal patients, according to Heather Wooten, an instructor of the history of medicine at the Institute for the Medical at the UT Medical Branch at Galveston. Smith's observations on the 1839 outbreak were published later that year, the first medical treatise in Texas.

Smith's treatise reported that yellow fever wasn't contagious, but the conclusion went unheeded, and he never discovered the disease's cause. Yellow fever outbreaks continued in Texas over the coming three decades, still a puzzle to medical practitioners, whose desperate measures, born of the observation that the outbreak ended when temperatures dropped, included keeping patients in cold storage.

The disease took its toll throughout much of the South during the Civil War, though Union blockades that extended some 3,500 miles along the Atlantic and Gulf of Mexico coastlines in reality probably protected port cities such as Galveston from incoming ships carrying yellow fever, Boutwell said.

Quarantine of Galveston

Reconstruction-era Houston became the military capital of Texas. In 1867, Gen. Charles Griffin, a U.S. Army officer assigned to take command of Texas, arrived in Galveston but moved his headquarters to Houston. When a bad outbreak of yellow fever hit the Galveston, his aides suggested he quarantine the island, but Griffin refused. The decision led to the state's most deadly outbreak.

The disease claimed the lives of 720 of Galveston's 13,000 people and 492 of Houston's 7,000, including some of the city's most prominent figures. Among them was 29-year-old Dick Dowling, who had led the Confederacy to victory at the Second Battle of Sabine Pass in 1863. Griffin too was felled by yellow fever.

The next time, leaders had learned their lesson, even if they didn't know why. When Galveston was struck by yellow fever again in 1870, Houston responded with an armed quarantine, which worked because the city's infected patients thus couldn't pass the virus on to inland mosquitoes.

For reasons experts still don't really understand, Houston had no serious outbreaks thereafter. In 1900, Dr. Walter Reed confirmed the theory that yellow fever is transmitted by mosquitoes, not by contact with bodily fluids of human sufferers, an advance that sparked the new fields of epidemiology and biomedicine and led to the resumption and completion of work on the Panama Canal.

Despite an effective vaccine, yellow fever still causes 30,000 deaths a year, 90 percent in Africa. The most recent fatal case in the U.S. occurred in 2002, a gas industry executive not diagnosed in time by his Corpus Christi doctors. He acquired the infection during a fishing trip in Brazil.

Some worry the disease could make a comeback. Dr. Herbert DuPont, a medical history buff and the director of UTHealth's School of Public Health's Center for Infectious Diseases, said he occasionally lectures there's no reason yellow fever couldn't return to the U.S. The World Health Organization recently expressed concerns yellow fever could follow the same path as dengue, chikungunya and Zika.

Still, Boutwell stresses that contemporary anxiety about such diseases can't compare with fears people living before the 20th century had about yellow fever.

"I don't think any disease today could terrorize a community like yellow fever in its day," said Boutwell, noting that today's medical sophistication provides a level of comfort and hope people didn't have then. "Perhaps only the threat of bioterrorism today rivals the dread and fear yellow fever brought to Houston and every other city it struck."