Off North Road
Tick bite, Part III
This is the third and last of a series, "Tick Bite," and describes other tick-borne diseases found on Martha's Vineyard in addition to Lyme disease and tularemia - that is, Rocky Mountain spotted fever, babesiosis, and ehrlichiosis.
The Lyme disease forum on April 28 at the Mansion House, with heavy lifting for its conception by Dr. Ilene Klein, was an unqualified success. (See The Times, May 4.) Take-home messages for me were three: 1. laboratory testing for Lyme disease (LD) is alive and well, much improved in sensitivity from the years of my practice; 2. researchers have discovered that a mouse that has been repeatedly bitten by ticks uninfected with LD loses its ability to produce enzymes which facilitate a successful transfer of LD bacteria. In other words, the previously bitten but uninfected mouse is protected by the previous bites alone without exposure to LD bacteria. This has implications for future LD vaccine; and 3. arrival at last of civil discourse in the discussion of late or chronic LD.
When I first started practice here I soon realized that the most serious summer ailment I would come across was Rocky Mountain spotted fever. It is a rare summer illness caused by the bite of a dog (wood) tick carrying small bacteria called rickettsii discovered by Dr. Howard Ricketts in 1896 along the Snake River Valley in Idaho. Soon the illness was reported generally throughout the U.S. It is the most severe and frequently reported rickettsial disease in this country, according to the Center for Disease Control and Prevention in Atlanta. Untreated it carried a 30 percent mortality. Since 1940 and the discovery of the antibiotics chloramphenicol and tetracycline, treatment has reduced mortality to 3 to 5 percent, still a significant risk.
The infection begins with sudden headache, often, "the most severe headache of my life," with aches and pains, sweats, prostration, and rash. The rash is a red dotted eruption of tiny skin hemorrhages and occurs usually after the fifth or sixth day. Sometimes it never occurs or comes later. The bacteria attack the cells lining small blood vessels where they cause small holes and oozing of blood into the tissues. This process can progress rapidly to involve many internal organs, the brain and spinal cord. Death can occur within the first 5 days. Treatment must start with the suspicion of the diagnosis because blood tests are often negative at first and take some time to become positive. Decreased platelet count and abnormal liver tests are suggestive; direct blood smears for bacteria, serum tests for antibodies and skin biopsy may yield early positive results. Response to antibiotics occurs within two to three days and becomes almost a diagnostic test. Recovery then is quick.
I remember one long discussion over a decision to treat a very ill child with fever without a tell-tale rash and whose labs were all negative. We suspected Rocky Mountain spotted fever. It is one of the few diseases, incidentally, where rash will appear on palms and soles. (Others are measles and syphilis.) Small children are more susceptible than adults as are patients of African and Asian descent and older adults. Anxious parents and I discussed reasons for treating before being certain of the diagnosis and the possible side effects of the drugs: with tetracycline, fetal damage in pregnancy and permanently stained teeth in kids under 9; with chloramphenicol, possible fatal aplastic anemia. The diagnostic hand rash and subsidence of fever and illness within five days for this child vindicated our early pre-emptive therapy. Later lab tests would confirm the diagnosis. No patient ever refused therapy and I recall no severe complications of those drugs used in this fashion.
Babesiosis is another tick-borne disease transmitted from mice in fashion similar to Lyme disease. Victor Babès, a Rumanian microbiologist, first co-reported the discovery of chromatic granules within bacteria which helped in diagnosis of disease in cattle in the late 1800s. He lent his name to babesiosis. The first domestic U.S. human case was reported in 1966, the beginning of an era for Vineyarders when tick-borne animal diseases came to prominence on-Island.
Babesiosis is similar to malaria of the tropics, caused by a small protozoon (one-celled organism) which infects and damages red blood cells. I saw my first inclusion rings within red blood cells infected with babesia sent over on a microscopic slide from Nantucket's Cottage Hospital sometime in the 1960s. Chills, sweats, and fever with muscle aches and pains, dark urine, and depression are major symptoms. Destruction of red blood cells results in anemia and injury to internal organs and kidney failure. Acute respiratory distress occurs in severe cases.
Treatment consists of a new drug similar to quinine plus azithromycin. Many cases occur with little or no signs of illness. At the extreme, a case may be life-threatening. Of four patients whom I knew, two died. One, a friend, died of combined babesiosis and Lyme disease. The double disease infection is particularly serious. (A significant number of deer ticks carry both Lyme disease and babesiosis.) Another, an elderly man, sought medical care late in his illness and died after two days in a Boston hospital. Two elderly women were diagnosed promptly, responded to antibiotics and remained well. Contrary to my experience, most patients with babesiosis survive and continue in good health. To place this serious infection in perspective, the CDC estimates that 95 percent of reported tick-borne illnesses in the U.S. are Lyme disease.
It was not until the end of the 19th century that scientists began to understand the nature of diseases transmitted to man from animal hosts by ticks. By the end of the 20th century, several such diseases have been recognized in the U.S. Ehrlichiosis is the most recent, recognized first as a veterinary disease in 1935 and then as a human infection in 1953 in Japan. According to the CDC, 600 cases have been documented in the U.S. since the 1980s.
The lone star tick and deer tick act as vectors, white deer as the infected source. Onset of illness is much the same as Rocky Mountain fever and babesiosis: high fever, aches and pains, severe headache and sometimes rash. It can be life-threatening or very mild. Many infections probably occur without the realization of the patient. Attack points in the body are the white blood cells which are responsible for fighting infection. Early diagnosis depends on finding microscopic accumulations of tiny bacteria within the cells. Later appearance of positive serology blood tests will confirm the diagnosis.
Treatment should begin presumptively without waiting for confirmation. Serious infection may cause widespread damage to organs, with death resulting. Doxycycline and other tetracyclines are effective treatment. Rifampin is an alternative, safe to use in pregnancy. Keep in mind the most important risk by far after a tick bite on the Vineyard is Lyme disease, but the rare forms of infection may be life-threatening.
The mantra for prevention for all tick-borne diseases is simple but imperfect. The CDC's list of preventives on their web site is about as complete as it gets:
To save tick, place with paper and penciled ID in plastic envelope in freezer. Give to doctor for help in diagnosis if sick within 2-3 weeks.
- Light colored clothing.
- Long pants tucked into socks, long sleeves.
- Repellents (Permethrin) on boots and clothing - lasts 4-5 days.
- Skin spray (DEET), caution with young children.
- Body check ("buddy system", full-length mirror) on return home.
- Remove attached tick with fine-tipped tweezers or shield fingers and grasp.
- Grasp tick close to the skin surface as possible, pull upward steadily, no twist or jerk, do not squeeze, crush, puncture or burn.
- Wash hands after handling, disinfect site.
References for Tick Bite I, II & III: web site for CDC, Viral and Rickettsial Zoonoses Branch; E-Medicine, Babesiosis by Sean O. Henderson, MD; Tick-borne Diseases in Massachusetts, A Physician's Manual, CDC, Massachusetts Department of Public Health, the RBBB Arthritis and Musculoskeletal Diseases Clinical Research Center at Brigham and Women's Hospital and Dr. Raymond Hoak.
For Parts I and II of the tick series see the Times, April 20 and May 4.
For Part I click here.
For Part II click here.