StoryImage( ‘/Images/Story//Auto-img-1119463263864.jpg’, ‘Photo courtesy of www.lyme.org’, ‘Rocky Mountain spotted fever (RMSF) rash caused by an organism called Rickettsia rickettsii. RMSF is reported from across North America, but is most prevalent in the eastern U.S. The Rocky Mountain wood tick, American dog tick, and Pacific Coast ticks transmit the disease. Signs of RMSF include a reddish-to-black rash (resembling measles), which starts on the extremities (e.g., wrists and ankles) and may spread to the entire body. Symptoms may include flu-like aches and pain, headache, chills, confusion, light sensitivity, and high fever. Death can occur without early treatment.’);
StoryImage( ‘/Images/Story//Auto-img-1119463835864.jpg’, ‘Robert A. Hedeen photo’, ‘The dangerous vector of Rocky Mountain spotted feverthe tick. (Photomicrograph 25xs)’);
With all of the recent attention focused on the tick-transmitted, joint-stiffening malady known as Lyme disease, a more serious tick-borne ailment has been relegated to the background. This disease is Rocky Mountain spotted fever and, where Lyme disease rarely results in the death of a victim, the mortality rate in untreated or improperly treated cases of RMSF ranges from 15 to 40 percent.
RMSF was first recognized by scientists as a distinct disease entity in the 1890s in western Montana. Originally it was thought the disease was confined to the Rocky Mountains, hence its name. By the 1930s, however, it had become established east of the Mississippi, and presently approximately 80 percent of the cases reported each year are from the eastern portion of the United States. It is also present in parts of Canada, Mexico, and South America.
Initially, the ailment became so important in the West that the U. S. Public Health Service established the Rocky Mountain Laboratory at Hamilton, Mont., in the heart of the Bitter Root Valley, specifically for the study of this disease. Personnel assigned to this famous laboratory quickly determined that RMSF was caused by an infectious agent called a rickettsia (a microorganism considered to be halfway between a virus and a bacterium), and it was transmitted to man and other mammals by certain species of ticks. While studying the epidemiology of RMSF, a number of scientists contracted the disease, and a few died.
Today, some 600 to 700 cases of spotted fever are reported in the United States each year, a figure some authorities consider to be a fraction of the actual number. As noted, the focus of the infection has shifted from west to east in the last 50 years with Maryland, Alabama, Georgia, Virginia, Tennessee, North Carolina, and Oklahoma being hot spots. It occurs more or less sporadically in most of the other eastern states.
From 1980 to 2004, 213 cases of RMSF were diagnosed in Illinois with the years 1980-1982 and 2001-2002 being when the disease was most active. That it is not strictly a rural disease is affirmed by the fact that in 1987 four cases were diagnosed in individuals who acquired the infection within the limits of New York City. While the deer tick has been incriminated as the principal vector of Lyme disease, the so-called wood, dog, and lone star ticks are the primary transmitters of the RMSF rickettsia.
When the rickettsiae are injected into the victim by the tick, they attack the muscles cells in the walls of arteries, causing blood and other fluids to leak into the surrounding tissues. In cases of severe, untreated attacks, massive damage may be done to the circulatory system, and death can result.
Flu-like symptoms develop three or more days after infection, and most victims develop a rash that starts on the ankles, feet, and wrists, gradually spreading to the torso and head regions. Sometimes the rash appears much later, and the organisms have time to devastate the body before treatment begins. When diagnosed early, RMSF is susceptible to certain broad-spectrum antibiotics.
As with Lyme disease, the best protection against tick bites is to wear protective clothing and the proper application of repellents when in tick country. The infectious microorganisms are not transmitted for several hours after the tick bores into your skin, so it is imperative that the entire body be checked frequently when in areas of tick activity. A hand mirror is useful in inspecting parts of the body not readily visible.
Some years ago before RMSF was reported from Texas, the late Dr. Cornelius B. Philip, a distinguished scientist from the Rocky Mountain Laboratory, predicted its presence there. It was a privilege for me to assist him in his quest for a Texas strain of the disease. We collected more than 250,000 lone star ticks from a prime area near San Antonio, but none of them proved to be infected as extracts from their bodies failed to produce symptoms in susceptible experimental animals. I recall Dr. Philip saying: We missed it this time, but we will get it next time. I know it is here. A few years later, his prediction was proven to be correct when infected ticks were found in an area where a person had contracted the disease and died.
Dr. Robert Hedeen is a former resident of Marylands eastern shore and resided in the Chicago area from 1960 to 1971. He is a retired professor emeritus of biological sciences in the University of Maryland system. He has published more than 30 scientific papers, has written numerous magazine articles, and is the author of two books on the natural history of the Chesapeake Bay.
From the june 22-28, 2005, issue