Native rats may have caused Mexican epidemics blamed on Spaniards
MEXICO CITY — Mexicans have long been taught to blame diseases brought by Spaniards for wiping out most of their Indian ancestors, but research suggests things may not be so simple.
Although the initial big die-offs are still blamed on the Conquistadors who started arriving in 1519, even more virulent epidemics in 1545 and 1576 may have been caused by a native blood-hemorrhaging fever spread by rats, Mexican researchers say.
The idea has sparked heated debate in Mexican academic circles.
One camp holds that the epidemics could have been spread by rats migrating during a drought cycle; others say newly arrived Spanishminersmayhavedisturbed the habitat of virus-carrying rodents while searching for gold and silver.
The revisionists draw support from one of the only authoritative firsthand accounts of the epidemics — a text lost for hundreds of years until it was found, misfiled, in a Spanish archive.
Francisco Hernandez, a physician to the Spanish king who witnessed the epidemic of 1576 and conducted autopsies, described a fever that caused heavy bleeding, similar to the hemorrhagic Ebola virus. It raced through the Indian population, killing four out of five people infected, often within a day or two.
The World Health Organization says the Ebola virus was first medically identified in Africa in 1976 after epidemics in northern Zaire, now the Democratic Republic of the Congo, and southern Sudan. It is one of the most virulent human viral diseases, causing death in 50 percent to 90 percent of cases. Several variants of Ebola virus have been identified.
“Blood flowed from the ears and in many cases blood truly gushed from the nose,” Francisco Hernandez wrote of the 1576 outbreak in Mexico. “Of those with recurring disease, almost none was saved.”
Dr. Rodolfo Acuna-Soto, a Harvard-trained epidemiologist who teaches microbiology at Mexico’s National Autonomous University, had Dr. Hernandez’s work translated from the original Latin in 2000. He followed up with research into outbreaks in Mexico’s isolated central highlands, where indigenous rats may have spread the disease through urine and droppings.
Dr. Acuna-Soto’s theory — which has been published in several scientific journals, including Emerging Infectious Diseases and the American Journal of Tropical Medicine and Hygiene — runs counter to reports that most of Mexico’s Indian population died of Spanish-imported diseases such as smallpox, to which their bodies had no immunity.
“This wasn’t smallpox,” said Dr. Acuna-Soto. “The pathology just does not fit.”
He said some historians in Mexico are offended by his theory.
“Much of the reason why these epidemics were left unstudied was that it was politically and institutionally easier to blame the Spaniards for all of the horrible things that might have happened,” he said. “It was ‘the official version’ of history.”
Imported diseases such as smallpox, measles and typhoid fever certainly caused huge numbers of deaths, starting in 1521. But the epi- demics of 1545 and 1576 struck survivors of the first die-offs and their children, who probably would have developed some immunity.
Although no reliable figure is available on Mexico’s population in the 1500s, estimates range from 6 million to 25 million.
The epidemic “was so big that it ruined and destroyed almost the entire land,” wrote Fray Juan de Torquemada, a Franciscan historian who witnessed the epidemic of 1576. He added that Mexico “was left almost empty.”
“Many were dead and others almost dead, and nobody had the health or strength to help the diseased or bury the dead.”
Other accounts mention a rodent invasion, and Dr. Acuna-Soto joined researchers from the United States to investigate whether an abnormally severe drought might have pushed rats into human settlements or vice versa.
Another Mexican specialist insists that the rodents mentioned in texts from the era probably came from Europe or Asia, carrying the bubonic plague, which sometimes caused its victims to vomit blood.
Elsa Malvido, a demographer, historian and specialist in ancient epidemics at the National Institute of Anthropology and History, said the plague could have caused the more severe hemorrhagic symptoms recorded by Dr. Hernandez, because it was attacking a population with no immunity whatsoever.
Dr. Carlos Viesca, director of medical history at the National Autonomous University of Mexico, said he is close to being convinced that the epidemics were native.
“The problem didn’t start in Acapulco or Veracruz,” the two main seaports where rats would have landed from overseas, he said. Instead, the disease appears to have started in the central highlands at a time when the Spaniards sent mining expeditions to unsettled parts of Mexico, suggesting that humansinvadedrodenthabitats,he said.
Relatively few Spaniards were affected by the outbreak, perhaps because they were protected in either eventuality: If the cause was bubonic plague or smallpox, their bodies had greater immunity to it; and if it was rodent-borne, they were less likely to come into contact with the animals.