Officials with the Centers for Disease Control and Prevention (CDC) have updated their 2006 guidelines for the diagnosis and treatment of tickborne rickettsial illnesses in the United States, according to information published in the CDC’s Morbidity and Mortality Weekly Report on May 13th. The update places a strong emphasis on early detection and treatment.

According to the report, tickborne rickettsial diseases can cause severe illness and even death in healthy children and adults. Three additional species – Rickettsia parkeri, Ehrlichia muris-like agent and Rickettsia 364D were linked in 2004 with human illness.

Holly M Biggs, MD, from the National Center for Emerging and Zoonotic Infectious Diseases at the CDC in Atlanta and colleagues from the CDC’s Rickettsial Zoonoses branch, along with outside public health professionals and clinical and academic specialists developed the guidelines to help providers and public health professionals in 5 target areas.


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First, the report notes that it is vital that health care providers recognize the epidemiological and clinical presentations of these diseases. In an interview with Infectious Disease Advisor, co-author of the report Christopher D Paddock, MD, of the National Center for Emerging and Zoonotic Infectious Diseases at the CDC said that “tickborne rickettsial diseases are can be quite difficult to recognize during the first few days of illness.” However, this early time is crucial for patients to receive treatment.

Second, physicians must be aware of the proper antibiotic protocols. During the interview, Dr Paddock explained that the most important takeaway for physicians from these guidelines is that “doxycycline is the treatment of choice for all tickborne rickettsial diseases, in patients of all ages, including young children.” In the past, use of doxycycline had been controversial due to tooth staining concerns, but the report notes “the use of doxycycline to treat children with suspected tickborne rickettsial disease should no longer be a subject of controversy.” The report noted that recent surveys showed that between 61-65% of physicians were unaware that doxycycline should be used to treat rickettsial illness in children younger than age of 8.

Use of doxycycline is linked to the third target area, because healthcare providers must understand that early treatment can prevent severe illness and death. “Several of these infections, particularly Rocky Mountain spotted fever and Ehrlichia chaffeensis ehrlichiosis, may progress rapidly to life-threatening manifestations,” Dr Paddock said.

Fourth, the guidelines note that physicians must request the correct diagnostic tests to confirm diagnosis, as well as completely understand the limitations and usefulness of these tests. Testing types include the serologic assay indirect immunofluorescence antibody (IFA), in addition to enzyme-linked immunosorbent assay (ELISA). Nucleic acid detection is another means of diagnosis. “Diagnostic molecular methods for tickborne rickettsial diseases have incorporated new technologies such as real-time PCR assays that offer the advantages of speed, reproducibility, quantitative capability, and reduced risk for contamination compared with conventional PCR assays,” Dr Biggs and colleagues noted in the study. Other methods include immunostaining of biopsy or autopsy tissue, blood-smear microscopy and culture.

The fifth and final target point emphasizes that healthcare workers need to report probable and confirmed instances of tickborne Rickettsial illnesses to public health authorities.

Dr Paddock concluded the interview by saying that physicians “who are familiar with the distribution and seasonality of tickborne rickettsial diseases are better positioned to consider these infections during the early stages of the illness when antibiotic therapy is most effective at preventing adverse outcomes.”

Reference

Biggs HM, Barton Behravesh C, Bradley KK et al. Diagnosis and management of tickborne rickettsial diseases: rocky mountain spotted fever and other spotted fever group rickettsioses, ehrlichioses, and anaplasmosis — United States: a practical guide for health care and public health professionals. MMWR Recommendations and Reports. 2016;65(2):1–44.