RMSF: Lethal, Underrecognized, and Undertreated

Paul G. Auwaerter, MD


October 27, 2014

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Hello. I am Paul Auwaerter, from the Division of Infectious Diseases at Johns Hopkins Hospital in Baltimore, Maryland, speaking for Medscape Infectious Diseases. I have just returned from IDWeek in Philadelphia, Pennsylvania. Of course the big news concerned Ebola, and rightfully so on so many fronts—not only here domestically in the United States but also overseas in West Africa.

However, I thought I would talk a bit about another illness that remains problematic in the United States, one that is often missed in early diagnosis, is not infectious to others, but with early recognition can abort a lethal outcome. This is a rickettsial illness called Rocky Mountain spotted fever. Robert Massung, from the Centers for Disease Control and Prevention (CDC), gave a splendid update[1] on rickettsial infections, which number over 19 species and are certain to grow worldwide. Rocky Mountain spotted fever, however, remains the one of gravest concern in the United States because of its high mortality rate when untreated.

Historically, Rocky Mountain spotted fever was called "black measles." Dr Massung made several other key points that are worth remembering. Although Rocky Mountain spotted fever is a tick-borne infection spread primarily by the dog tick and is seen in the entire continental United States, it seems to be most common in Southeast and South Central states, such as the Carolinas, Arkansas, and so on.

It is an illness that needs to be recognized in the differential diagnosis after tick exposure and treated empirically. Dr Massung advised that anyone with the potential for tick exposure, especially children or adults with fever and headache, should probably receive doxycycline as the treatment of choice because the characteristic petechial rash can be a later finding, and 10% of people do not develop a rash. The pathogenesis is unique such that it causes an endovascular infection, and subsequent vasculitis leads essentially lock-step to problems with multiorgan system failure onset at day 5. Hence, all the studies, albeit observational and retrospective, suggest that if therapy is started within 5 days of exposure, morbidity and mortality are vastly reduced.

Reluctance to Use Doxycycline in Children

Another important point is that, certainly in pediatric populations, there remains a general reluctance to use doxycycline. This reluctance is related to problems with oral tetracycline, which is not even available now because of manufacturing problems, but had caused dental staining with prolonged use in children under the age of 8 years. However, because all tetracyclines have this label from the US Food and Drug Administration (FDA), many people are reluctant to prescribe it.

Although studies have not been large, many conducted here in the United States and in Israel have suggested that doxycycline does not cause any tooth staining when used at younger ages, even in very young children, and for limited periods of time.[2,3] The CDC, American Academy of Pediatrics, and the Red Book all suggest that doxycycline is the treatment of choice for children, as well as adults, with Rocky Mountain spotted fever, and that there should be no reluctance in administering the medication.[4,5]

With those key points, the early recognition of this infection and use of doxycycline in children are important because we continue to see cases of delayed diagnosis or reluctance to give what can be a lifesaving drug to young children. The alternatives, such as chloramphenicol, are no longer available on any basis.

Dr Massung recommended implementing a national campaign to help educate family practitioners and pediatricians about the utility of doxycycline, pretty much for any tick-borne illness but especially for Rocky Mountain spotted fever, at a young age. In addition, he suggested that the FDA probably should strike the dental enamel warning from doxycycline, which may help assuage fears and concerns that prevent people from prescribing it properly.

Thanks so much for listening. Keep in mind that doxycycline in children, for short courses, is not of any concern from a dental perspective.


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