Story of Rocky Mountain Spotted Fever (USPHS, 1968)

Story of Rocky Mountain Spotted Fever (USPHS, 1968)


[Music] [Narrator:] Rocky Mountain spotted fever, a mysterious and usually fatal disease, was often called mountain fever, blue death, or black measles. It was much feared by early settlers of the Rocky
Mountain region. The brown areas denote the counties from which
one or more cases had been recognized and reported as early as 1905. It was especially dreaded in western Montana
where four of every five victims died. Some people are convinced that the poison is in
freshet water. Others say it is given off by decaying sawdust and
pine needles. A few Indians believe… it comes from the tick bite. Mr. Hawkins swears his boy got it from being near bare grass blossoms last June. It took a doctor almost three days to reach here. It was too late. Stimulated by Montana health authorities,
scientists of national repute began experiments that brought exciting hope. Spotted fever transmitted by woodtick. Researchers had just completed an experiment
that opens the field for an effective battle against this terrible disease. Dr. H. T. Ricketts used the blood from a spotted-
fever patient to infect experimental tick hosts. He permitted the suspected vector, dermacentor
andersoni, to take a blood meal from the infected guinea pigs. Now would the ticks from an infected host be
infected, and would they transmit the infection to a normal host? The suspects did transmit spotted fever. These abandoned buildings immediately became
laboratories. The federal aid and R. A. Cooley’s Montana
program were now joined against a dangerous disease that challenged a
coordinated effort for four decades. The initial studies concentrated on the biology and
possible control of the tick. Tick-flagging originated with these early workers
and is still a most effective technique for collecting the wood tick. Dermacentor andersoni was found to infest both
small and large animals, and to have a two-year life cycle. Spring-hatched larva, the first of two immature
stages, were found drawing blood from small animals. These transform to nymphs, who go into
hibernation from late summer until the following spring. The second spring, a second stage. The nymphal ticks feed on small animals also. Infected larva or nymphs were found to infect their
hosts whose blood then became infectious for simultaneously feeding ticks. These will transform to adults by late summer, then
hibernate. In the third spring, which completes the two-year
cycle, the adults feed on large animals and man. Infected ticks, feeding on the small or large
animals, do not cause obvious illness. The male has a mottled grey color pattern. Before engorgement, this female was a dark
reddish brown. They mate while feeding. Either sex may transmit the disease. Each female deposits 6,000 to 8,000 eggs on the
ground. The larva from these may be infected and maintain
their infection to adulthood. The disease is usually transmitted to man by adult
ticks, of which about one percent are infected. A tick-host rodent-control program was initiated in
a severely affected section of Western Montana in 1911. Poisoned grain killed the rodents essential to the
survival of the immature ticks. This program reduced the tick population and was
continued for about twenty years until more effective disease control appeared. An extensive livestock-dipping program was also
maintained. This was a direct attack on the adult ticks. These and minor control measures were effective
but could only be afforded in limited areas. This was a typical tick control-era setting. It was in this laboratory that the first investigator
became fatally infected. The bacterial-like infectious agent was found in all
tissues of the tick. A stained preparation of infected tissue shows the
red-stained agent, taxonomically designated rickettsia rickettsia. Virulent strains killed guinea pigs in 7 to 14 days. The scrotum and footpads became inflamed. These tissues finally died. An autopsy shows testes inflamed and adherent to
body wall. Spleen enlarged. And lymph nodes enlarged. In 1921, investigators moved to a vacated country
schoolhouse where another heartening breakthrough was made by Drs. Spencer and
Parker. Spotted fever vaccine found. Spotted fever vaccine proven. Immunity through vaccination seems assured. Basically, the vaccine was made by grinding the
highly-infected adult ticks in a phenol solution. Hand subrogation removed the coarse tissue. Clear vaccine contains the killed immunity-
producing rickettsii. A kitchen pressure cooker was used for a
sterilizing autoclave. An alcohol lamp for flaming and a syringe for
bottling the vaccine. Nineteen twenty-five, first year’s output. Thousands exposed. Thirty-four vaccinated. Research expanded rapidly after 1928 when the
state of Montana provided the first safe modern facility. A tick-destroying parasite was now introduced to
supplement the current rodent poisoning and stock-dipping control programs. This parasite, [?], deposits eggs in the nymphs by
a stinging action. The maggot stage of this parasite kills the
engorged nymphs by consuming their host’s internal organs. After a pupal stage, they emerge as adult
parasites, ready to parasitize other nymphs. Millions of these parasites were reared for release
near a small tick host lairs. Although parasites were successfully maintained in
the laboratory, no parasitized nymphs could be collected the following seasons. The startling recognition of spotted fever in some
eastern states suddenly made this a nationwide problem. Because of these pressures, the federal
government purchased the Montana facility. A second unit was added in 1934. Millions of highly-infected ticks could now be
reared annually for increased vaccine production. Mechanical grinders facilitated mass production. [Sound of machinery] A separatory funnel in a sterile room instead of the
syringe for bottling. Potency and sterility testing could now be performed at the manufacturing laboratory instead of at national headquarters. After 15 years of use, records demonstrated the protective value of the vaccine. In comparison with the production of only enough vaccine for 34 immunizations in 1925, there was now enough for use by physicians throughout the nation. By 1940, additional facilities made it possible to accommodate more scientists and broaden the research to include other diseases in nature communicable to man. The diseases studied by then are noted in the top line of each experimental animal card. Another milestone in the expanding struggle against spotted fever was Dr. H. R. Cox’s first time culturing a rickettsii in embryonic egg tissue. Rickettsia rickettsii could now be produced more
efficiently, and it eliminated the stray tick hazard. Eggs containing eight-day embryos were
inoculated with spotted fever, and incubated further. Highly-infected yolk sacs were harvested from
mechanically-opened eggs. Yolk sacs were blended, and a phenol formula solution was added to kill and preserve the rickettsii. And fats were extracted with ether. By now, field information on ticks from across the nation was needed to complete epidemiological data on the various tick-borne diseases. The entomologists found many species, some in the ground… some on trees and in the jungle, as well as in the desert. Information on their taxonomic determination, disease transmission potential, and distribution were essential. Three species were found to infect man: the wood tick, [Map of US shown] the dog tick, [Map of US shown] and the Lone Star tick. Spotted fever is still an ever-present danger to those who live in or visit wood tick-infested areas. These are typical exposures to the wood tick. Exposure to the dog tick could, of course, take
place in the home. The time of greatest exposure to the tick is in the
spring and early summer. That this tick is infected. Contrary to common belief, the tick’s mouth parts seldom remain imbedded in the skin after the specimen’s removal. Influenza-like symptoms appear about one week
after the bite of an infected tick. Serological diagnosis for tick-borne diseases was a routine service at the Rocky Mountain Laboratory. Physicians also depended upon its scientists for
the most recent information on these diseases. One such test was the Weil-Felix for spotted fever. Treatment was usually symptomatic. In other words, major discomforts could be
alleviated, but the disease would run its course. A rash usually appears on the wrists and ankles
sometime during the first week. It soon covers the entire body. In severe cases, it later becomes confluent. When the illness is fatal, death usually occurs during the second week of illness. Non-fatal cases are bedfast two to three weeks. Vaccination is advisable each spring for those
extensively exposed to ticks. In high-incident areas, it was made available
through free vaccination clinics. Avoid the carriers. They wait on low vegetation. Do not wear clothing that is open at the bottom. They are attracted by the body odor under the
garment. To avoid bites, each garment should fit over the
one above. Even so, the entire body and both sides of the
clothing should be thoroughly examined before retiring. Once on the neck, it is usually felt before it
attaches. The long-sought wonder cure came in the late 1940s with the commercial introduction of certain antibiotics. They have greatly reduced the death rate and the fear of this once dread malady has essentially disappeared. Spotted fever fought back for half a century, from Ricketts’ tick transmission experiment to antibiotics, and took the lives of five researchers. McClintock. McCray. Cowan. Kerlee. To the memory of our fellow laboratory workers who, while engaged in the study of Rocky Mountain Spotted Fever, have contracted the disease and died. As after the victory over other historically notorious infectious diseases, these costs are now being repaid. The developments and knowledge gained have made fatal spotted fever cases the exception and eliminated the universal fear. It is no longer a disease of mystery. [Music]

Leave a Reply

Your email address will not be published. Required fields are marked *