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SASTM Newsflash - Spotted fever Rickettsiosis, California USA - New species


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SASTM Newsflash




Fall and winter bring on young active ticks, and with that the risk of disease, according to a newsletter released by the Contra Costa Mosquito and Vector Control District. "In addition to spreading Lyme disease, researchers now say ticks are also responsible for transmitting a previously unknown disease that is related to Rocky Mounted spotted fever," the release stated. The new bacterium was recorded in 4 human cases statewide, with 2 of those cases in Contra Costa County.


The newsletter reads: "The _Rickettsia philipii_ bacterium is transmitted by the Pacific Coast tick (_Dermacentor occidentalis_), which is one of the 3 primary ticks that can be found across California. So far scientists have found ticks infected with this new bacterium in at least 8 California counties.


"While a small percentage of adult Pacific Coast ticks have tested positive for the disease thus far, researchers find that young nymphs are testing positive as well. This makes prevention very important because these young ticks are very small and very difficult to see.

Symptoms can include fever, headache, fatigue, and what appears to be a blackened scab at the site of a tick bite.


"In addition to the discovery of this new form of spotted fever, California researchers also confirm that the western black-legged tick (_Ixodes pacificus_), which is the primary tick responsible for spreading Lyme disease in California, is also capable of transmitting a newly recognized type of tickborne relapsing fever caused by the bacterium _Borrelia miyamotoi_. The symptoms of this illness include a fever that comes and goes, as well as headache and muscle aches.


"As of the writing of this article, there have not been any reports of humans infected with _Borrelia miyamotoi_ in California, but scientists say the fact that a tick that already exists in California is capable of transmitting this disease makes it more important than ever for outdoor enthusiasts to take the risk of tickborne illness very seriously.


"Using a tick repellent, wearing light-colored long sleeve clothing that is carefully tucked in at the waist and socks, and doing a tick check after exposure to wooded or grassy areas are all important ways to prevent tick bites and reduce the risk of tickborne illness. Pet owners should consider using a veterinarian-approved flea and tick product on pets that roam outdoors because it can reduce the chance a pet might bring an infected tick home. Pet owners should also perform tick checks on pets as another way to reduce disease risk within a home.


"Prevention is the key to reducing risk from tickborne diseases. In Contra Costa County, only about 2 percent of ticks are infected with Lyme disease. With such low risk of disease, there is no guarantee that a person who is bitten by an infected tick will also become infected.


"Various studies indicate that the tick must feed on a person for 2-24 hours before any disease-causing bacterium can be transferred. That is why prevention is so important. While tickborne disease may be unlikely in our county, learn to recognize the symptoms and consult your doctor if they appear after a tick bite.


"Anyone who finds a tick on a person should remove the tick by pulling gently, but firmly, with tweezers placed as close to the surface of the skin as possible. The Contra Costa Mosquito & Vector Control District does provide a free tick identification service for county residents, but does not test ticks for disease, as such tests cannot determine whether or not the tick has actually transmitted the pathogen.


"The District can provide a list of commercial laboratories that citizens may contact for tick testing should they be bitten by a tick; however at this time there are no current tests available for the newest tickborne disease caused by _R. philipii_ bacterium."


Communicated by: ProMED-mail


The following in reference to spotted fever caused by _Rickettsia philipii_ is extracted from the Monterey County, California health department journal Vida Sana, dated 23 Aug 2013, "_Rickettsia philipii_ (formerly known as _Rickettsia_ 364D) is an emerging human tickborne disease in California. In 2008, the 1st human case was identified in a resident of Lake County, California. By the end of 2012, 10 cases had been confirmed among residents of Lake, Contra Costa, Monterey, Orange, and Santa Clara counties. There have been 2 cases reported among Monterey County residents, one confirmed and one suspected.


"_R. philipii_ is a member of the spotted fever group _Rickettsia_ (SFGR). Symptoms of _R. philipii_ rickettsiosis include fever, rash, eschar, headache, myalgia, anemia, thrombocytopenia, and/or hepatic transaminase elevation. The eschar is usually an isolated ulcer with raised erythematous margins and a black core (see photo at the end of this update [at the URL above]). It is often surrounded by generalized edema and erythema. Symptoms develop 3 to 14 days after exposure at the site of a known or presumed tick bite.


"_R. philipii_ is transmitted by Pacific Coast ticks (_Dermacentor occidentalis_, see photo at the end of this update [at the URL above]). _R. philipii_ has been detected in ticks collected from Alameda, Contra Costa, Lake, Los Angeles, Mendocino, Monterey, Orange, Riverside, San Bernardino, San Mateo, Santa Clara, Shasta, and Ventura counties. Adult Pacific Coast ticks are active January through June and can be found in dry, grassy areas. Nymphal ticks are active May through August and likely live in leaf litter and wood products. Both adults and nymphs are thought to transmit _R. philipii_ to humans.

Tick attachment time prior to transmitting _R. philipii_ is likely between 2 and 20 hours, which is shorter than seen with Western black legged ticks and Lyme disease (greater than 24 hours).


"Treat suspected cases of _R. philipii_ rickettsiosis appropriately. Doxycycline is the 1st line treatment for adults and children of all ages:

Adults: 100 mg po q 12 hours

Children under 45 kg [99 lb]: 2.2 mg/kg body weight po bid


"Patients should be treated for at least 3 days after the fever subsides and until there is evidence of clinical improvement. Standard duration of treatment is 7-14 days. Do not delay treatment while awaiting laboratory confirmation. Treatment decisions should be based on epidemiologic and clinical evidence."


Contra Costa County, with a population of about 1 million in 2010, is a suburban county in the San Francisco Bay Area of the US state of California that is bounded on the south and west by Alameda County; on the northwest by San Francisco Bay; on the north by San Pablo Bay and Suisun Bay; and on the east by the San Joaquin River




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The content and opinions are neither pre-screened nor endorsed by the SASTM. The content should neither be interpreted nor quoted as inherently accurate or authoritative.

The information provided in SASTM Newsflashes is collected from various news sources, health agencies and government agencies. Although the information is believed to be accurate, any express or implied warranty as to its suitability for any purpose is categorically disclaimed. In particular, this information should not be construed to serve as medical advice for any individual. The health information provided is general in nature, and may not be appropriate for all persons. Medical advice may vary because of individual differences in such factors as health risks, current medical conditions and treatment, allergies, pregnancy and breast feeding, etc. In addition, global health risks are constantly evolving and changing. International travelers should consult a qualified physician for medical advice prior to departure.

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