Thursday, February 25, 2010

Did spirochetes kill off the Indians in Massachusetts before the Mayflower landed?

ResearchBlogging.orgThe coast of present-day Massachusetts was inhabited by several Native American tribes in the early 17th century.  Fishermen, traders, and explorers from the Old World encountered the Indians during their occasional travel through the area.  However by the time the Mayflower landed in Plymouth in 1620 to establish a colony, a mysterious epidemic had ravaged coastal New England, killing up to 90% of the indigenous population during the years 1616 through 1619.  Experts have yet to agree on the cause of the epidemic.  Smallpox, plague, and yellow fever, all highly lethal diseases, have been blamed.

Native American tribes of southeastern Massachusetts, approx. 1620 (Figure 1 from Marr and Cathey)

An article in the new issue of Emerging Infectious Diseases offers leptospirosis, caused by Leptospira spirochetes, as another possible agent of the 1616-1619 epidemic.  This is based not on any new information but on an examination of the lifestyle of the Native Americans of early 17th century New England.

Rats infected with Leptospira may have stowed away in the ships that sailed from Europe to the New World.  Because Leptospira lives in the kidney tubules of chronic carriers, infected rats released into the New World would have contaminated their surroundings every time they urinated.  Since Leptospira can survive in moist soil and fresh water, indigenous rodents and other animals could have become chronically infected with Leptospira, further spreading the spirochete throughout the region. The Indian lifestyle provided plenty of opportunities for exposure to Leptospira through skin abrasions and swallowing of contaminated water or food.  Their high-risk activities included the following:
  • walking around barefooted
  • storing food accessible to rodents
  • swimming and bathing in streams and ponds
  • working on moist soil to raise and harvest crops
Leptospira has little effect on the health of carrier animals yet can cause humans to fall ill.  Many escape with what may be confused with a mild case of the flu, but some end up suffering with life-threatening symptoms.  Eyewitnesses of the 1616-1619 epidemic reported that victims were afflicted with skin lesions, severe headaches, yellowing of the skin (likely jaundice), and bloody nose (possibly from lung hemorrhage), which are all symptoms of the severe form of leptospirosis.  Even today leptospirosis can be deadly with reported fatality rates of greater than 50% among those with severe lung hemorrhaging.

While the authors should be commended for even considering a disease of a spirochete that is often ignored (at least by those in the developed world), I don't think Leptospira is what killed off the Indians. One strong argument against leptospirosis being the cause of the 1616-1619 epidemic is that Leptospira is not hardy enough to survive the cold winters that Mother Nature inflicts upon New England.  Since the fatalities continued through the winter, leptospirosis is unlikely to be the culprit.

Whatever the cause, the epidemic may have been a pivotal event that facilitated English colonization of coastal Massachusetts since the surviving Indians lacked the capacity to resist the newcomers.

Featured paper

Marr, J.S., & Cathey, J.T. (2010). New Hypothesis for Cause of Epidemic among Native Americans, New England, 1616–1619 Emerging Infectious Diseases, 16 (2), 281-286 DOI: 10.3201/eid1602.090276

1 comment:

  1. Thanks for your interest in our article. To address your comment about
    leptospires not being hardy enough to survive the winter: In fact, the
    organism can survive the winter and be re-introduced in the spring
    from chronically infected animals, making the disease a seasonal
    affair or a smoldering endemic with seasonal peaks, as demonstrated by
    autochthonous cases that occur year after year in northern latitudes
    (see recent ProMed reports, PRO/AH/EDR> Leptospirosis, fatal -
    Ireland, archive number 20100106.0055 06-JAN-2010, 20100105.0041
    05-JAN-2010). As noted on wikipedia
    (, the bacteria are found
    worldwide, except Antartica. In the case of the Native Americans,
    exposure to freshly shed leptospira in rodent urine or to animals
    during butchering would allow for year-round cases, but there is no
    evidence that cases necessarily occurred during the winter. A close
    reading of primary sources indicates there were few or none. There
    were probably bodies, but few or no acute cases.