(Photo Credit- CDC)
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Although they’ve undoubtedly been around and infecting mankind for a long time, in recent years we’ve seen a surge in the number of `new’ tickborne illnesses identified in the United States and around the world. And as new tests are being developed and deployed, we are finding out that the number of tick borne infections reported previously have only represented `the tip of the iceberg’.
Last year, the CDC revised their Estimate Of Yearly Lyme Disease Diagnoses In The United States, indicating that the number of Lyme Disease diagnoses in the country is probably closer to 300,000 than the 30,000 that are officially reported each year to the CDC.
In 2012, the CDC announced the identification of the The Heartland Virus in two farmers from the Midwest (see a New Phlebovirus Discovered In Missouri). Last March (see MMWR: Heartland Virus Disease — United States, 2012–2013) we saw an update from the CDC indicating that 6 more cases had been identified (5 in Missouri, 1 in Tennessee), and last month we saw the Oklahoma DOH Reports 1st Heartland Virus Fatality.
Like many vector-transmitted diseases, the Heartland Virus is likely under-reported.
A couple of weeks ago, in The Tick Borne Identity, we looked at a study out of the University of North Florida, that claims to have found a new strain of Borellia (aka Lyme Disease), that is prevalent in ticks in the Southeastern states. In 2011 we saw the NEJM: Emergence Of A New Bacterial Cause Of Ehrlichiosis, while in recent years Babesia microti infection (see Maryn McKenna On Babesia And The Blood Supply) is increasingly viewed as a serious public health concern.
One of the more recent discoveries involves a tickborne bacteria called Borrelia miyamotoi, which was first described in ticks Japan in the mid-1990s, . We’ll let the CDC carry the narrative for a spell:
What you need to know about Borrelia miyamotoi, a newly described human pathogen
What is Borrelia miyamotoi?
Borrelia miyamotoi are spiral-shaped bacteria that are closely related to bacteria that cause tick-borne relapsing fever (TBRF). They are more distantly related to the bacteria that cause Lyme disease. First identified in 1995 in ticks from Japan, the bacteria have since been detected in two species of North American ticks, the black-legged or “deer” tick (Ixodes scapularis) and the western black-legged tick (Ixodes pacificus). These ticks are already known to transmit several diseases, including Lyme disease, anaplasmosis, and babesiosis.
What type of illness does B. miyamotoi cause?
Human infections with B. miyamotoi were first described in 2011 in a report from Russia. Most of the patients had fever, headache, and muscle aches--symptoms typical of TBRF. Symptoms similar to those of Lyme disease, such as the erythema migrans rash (bull’s-eye rash), arthritis, or facial palsy, were uncommon.
Recently, three cases of human infection with B. miyamotoi were identified in the United States. One patient was an elderly, immunocompromised woman with confusion and an unsteady gait. The bacteria were seen in samples of the patient’s spinal fluid, and she recovered when treated with antibiotics. The two other patients had fever, chills, and muscle aches, similar to the symptoms of the patients in Russia.
While the number of B. miyamotoi cases reported in the United States remains small, surveillance and testing is just in its infancy. To that end we have research, published in the July edition of the EID Journal, that looks at the seroprevalence of B. miyamotoi infection in archived blood samples (collected 1991–2012) from residents of the Northeastern United States.
Volume 20, Number 7—July 2014
Research
Borrelia miyamotoi sensu lato Seroreactivity and Seroprevalence in the Northeastern United States
Peter J. Krause
, Sukanya Narasimhan, Gary P. Wormser, Alan G. Barbour, Alexander E. Platonov, Janna Brancato, Timothy Lepore, Kenneth Dardick, Mark Mamula, Lindsay Rollend, Tanner K. Steeves, Maria Diuk-Wasser, Sahar Usmani-Brown, Phillip Williamson, Denis S. Sarksyan, Erol Fikrig, Durland Fish, and the Tick Borne Diseases Group
Abstract
Borrelia miyamotoi sensu lato, a relapsing fever Borrelia sp., is transmitted by the same ticks that transmit B. burgdorferi (the Lyme disease pathogen) and occurs in all Lyme disease–endemic areas of the United States. To determine the seroprevalence of IgG against B. miyamotoi sensu lato in the northeastern United States and assess whether serum from B. miyamotoi sensu lato–infected persons is reactive to B. burgdorferi antigens, we tested archived serum samples from area residents during 1991–2012.
Of 639 samples from healthy persons, 25 were positive for B. miyamotoi sensu lato and 60 for B. burgdorferi. Samples from ≈10% of B. miyamotoi sensu lato–seropositive persons without a recent history of Lyme disease were seropositive for B. burgdorferi.
Our results suggest that human B. miyamotoi sensu lato infection may be common in southern New England and that B. burgdorferi antibody testing is not an effective surrogate for detecting B. miyamotoi sensu lato infection.
In the same EID journal edition, in - Human Exposure to Tickborne Relapsing Fever Spirochete Borrelia miyamotoi, the Netherlands by Fonville M, Friesema IHM, Hengeveld PD, Docters van Leeuwen A, Jahfari S, Harms MG, et al. - we see a case described as:
Conditions reported to be associated with B. miyamotoi infection were systemic, including malaise and fever, meningoencephalitis, and neurologic symptoms. Because of the nature of these manifestations and because regular diagnostic tests for B. burgdorferi will most probably not detect B. miyamotoi infections (3,5), B. miyamotoi infections may remain undiagnosed.
Nevertheless, the relationship between B. miyamotoi infection and illness is not very well established; the case-patients reported, including the patient in the Netherlands, were usually hospitalized, severely ill, and often immunocompromised (3–5). The extent to which B. miyamotoi causes infection and disease in immunocompetent persons is unknown.
The authors of the first EID report (both of which are worth reading in their entirety), conclude by writing:
The determination of B. miyamotoi sensu lato seroprevalence in our population is important because it indicates that this pathogen may infect persons at a rate that is similar to that of B. microti in the northeastern United States (16,23,24). Our data suggest that acute B. miyamotoi sensu lato infection in some persons may be misdiagnosed as Lyme disease because of the presence of antibody to B. burgdorferi from a previous B. burgdorferi infection, a false-positive test reaction, and/or cross-reactivity.
Antibody testing for B. burgdorferi, however, is not adequate to detect infection with B. miyamotoi sensu lato in the United States. The potential for misdiagnosis may be greater in locations like northern California, were the prevalence of B. miyamotoi sensu lato in ticks equals or exceeds the prevalence of B. burgdorferi in ticks (32). Further studies are needed to better characterize the epidemiology and improve the serodiagnosis of human B. miyamotoi sensu lato infection.
