#17,314
Although much of the country still dealing with winter, tick season is just around the corner, and in addition to the long-established threat from Lyme disease, the CDC maintains a long (and growing) list of tick borne pathogens that can be found in North America, including:
Anaplasmosis, Babesiosis, Borrelia miyamotoi, Colorado tick fever, Ehrlichiosis, Heartland virus, Lyme disease, Powassan disease, Rickettsia parkeri rickettsiosis, Rocky Mountain spotted fever (RMSF), STARI (Southern tick-associated rash illness), Tickborne relapsing fever (TBRF), ularemia, and 364D rickettsiosis
Two relatively recent additions to this list have been made in the past decade;
- Bourbon virus infection has been identified in a limited number patients in the Midwest and southern United States. At this time, we do not know if the virus might be found in other areas of the United States.
- Heartland virus cases have been identified in the Midwestern and southern United States. Studies suggest that Lone Star ticks can transmit the virus. It is unknown if the virus may be found in other areas of the U.S.
Just over a decade ago, in a New Phlebovirus Discovered In Missouri, I wrote about the CDC’s announcement of a new tick-borne virus phlebovirus detected in two Missouri farmers with no epidemiological links and living 60 miles apart.
Dubbed `The Heartland Virus’ (HLV), the virus was named after the Heartland Regional Medical Center in St. Joseph, Mo which alerted the CDC back in 2009 about these cases.
Phleboviruses are part of the large family Bunyaviridae - which includes such infamous pathogens as Crimean-Congo hemorrhagic fever and Rift Valley Fever. Bunyaviruses - are mostly spread via arthropod vectors (ticks, mosquitoes & sand flies).
This newly described `Heartland virus’ is genetically similar to another tick borne virus identified in China in 2011, called SFTS (see EID Journal Severe Fever with Thrombocytopenia Syndrome Virus, Shandong Province, China Jun 2012).
All of which brings us to an EID Journal Dispatch, which describes a fatal case of Heartland Virus infection from a man in Virginia, and suggests the range of this virus may be increasing across the country.
Fatal Case of Heartland Virus Disease Acquired in the Mid-Atlantic Region, United States
Sichen Liu1, Suraj Kannan1, Monica Meeks, Sandra Sanchez, Kyle W. Girone, James C. Broyhill, Roosecelis Brasil Martines, Joshua Bernick, Lori Flammia, Julia Murphy, Susan L. Hills, Kristen L. Burkhalter, Janeen J. Laven, David Gaines, and Christopher J. Hoffmann
Abstract
Heartland virus (HRTV) disease is an emerging tickborne illness in the midwestern and southern United States. We describe a reported fatal case of HRTV infection in the Maryland and Virginia region, states not widely recognized to have human HRTV disease cases. The range of HRTV could be expanding in the United States.
(SNIP)
Since HRTV was discovered in 2009 in Missouri, USA, human HRTV disease cases have also been reported in Kansas, Oklahoma, Arkansas, Tennessee, Kentucky, Indiana, Illinois, Iowa, Georgia, Pennsylvania, New York, and North Carolina according to the Centers for Disease Control and Prevention (CDC; https://www.cdc.gov/heartland-virus/statistics/index.html). Studies have documented HRTV RNA in A. americanum ticks and HRTV-neutralizing antibodies in vertebrate animals in these states (8–13). However, the distribution of A. americanum ticks is wider and growing, possibly because of climate change, which could lead to HRTV range expansion (3,11).Of note, vertebrate animals with neutralizing antibodies to HRTV have been documented in states without confirmed human cases, including Texas, Florida, South Carolina, and Louisiana in the south and Vermont, New Hampshire, and Maine in the northeast (12,13). To date, no seropositive animals have been reported from Maryland or Virginia in the mid-Atlantic region. We describe a fatal human case of HRTV infection with secondary HLH in which initial infection likely occurred in either Maryland or Virginia.
(SNIP)
The patient was a man in his late 60s who had a medical history of splenectomy from remote trauma, coronary artery disease, and hypertension. He was seen at an emergency department in November 2021 for 5 days of fever, nonbloody diarrhea, dyspnea, myalgias, and malaise. At initial examination, he appeared fatigued but was alert and oriented. Laboratory results were notable for hyponatremia, mildly elevated liver enzymes, leukopenia, and thrombocytopenia (Table).
The patient had homes in rural areas of Maryland and Virginia and had not traveled outside of this area in the previous 3 months. He spent time outdoors on his properties but did not recall attached ticks or tick bites. Despite the lack of known tick bites, the symptom constellation and potential exposure led clinicians to highly suspect tickborne illness; they prescribed doxycycline and discharged the patient home.
Two days later, on day 7 after symptom onset, the patient returned to the emergency department with confusion, an unsteady gait, and new fecal and urinary incontinence; he was admitted for inpatient management. He had progressive encephalopathy with hyponatremia and rising transaminases (Table). Results of neurologic workup and imaging were unremarkable (Table). Computed tomography imaging of the abdomen and pelvis showed new pelvic and inguinal lymphadenopathy. The patient was treated with hypertonic saline, intravenous doxycycline, and piperacillin/tazobactam.
Because of clinical deterioration, he was transferred to a tertiary care center. At arrival at the tertiary center, he was fatigued and disoriented. Physical examination demonstrated new hepatomegaly and lower extremity livedo reticularis. Results of broad testing for infectious etiologies was negative (Appendix Table). Laboratory results demonstrated increased creatine kinase (9,567 U/L), lactate (2.5 mg/dL), lactate dehydrogenase (1,709 U/L), and ferritin (47,445 ng/mL). Interleukin 2 receptor, a marker for HLH, was also elevated (9,390 pg/mL) (Table). Immunosuppressive agents for management of likely secondary HLH were deferred while clinicians conducted a diagnostic work-up of the underlying disease process. An arboviral disease was the leading diagnostic consideration, but limited availability of commercial diagnostic testing for tickborne diseases delayed diagnosis.
The patient’s clinical course continued to deteriorate. He had acute respiratory failure, renal failure, and a cardiac arrest. He was transitioned to comfort care and died on day 13 after symptom onset.(SNIP)
Conclusions
HRTV disease has been reported in >50 patients in states across the midwestern and southern United States (1–7). A bite from an A. americanum tick is the only known means of environmental HRTV transmission (1). Corresponding to A. americanum tick seasonal activity, all reported cases have occurred during April–September, and symptoms developed during June in most case-patients (1,3). Because the incubation period for HRTV is estimated to be 2 weeks, this patient was likely infected in late October. Adult ticks are minimally active at that time; however, larval ticks can become infected with HRTV and can still be observed during October (1,14). We suspect this patient was bitten by larval ticks unknowingly because of their small size, and that the bite marks healed before his clinical signs and symptoms appeared.
Maryland and Virginia fall within the A. americanum tick distribution area, but we found no previous reports of HRTV illness from those states during a literature search, and CDC had no reported cases from those states. Among 193 ticks collected during tick drags of both properties, no HRTV-infected vectors were found, but this result does not exclude HRTV in either state. Previous studies report low overall minimum infection rates among A. americanum ticks from other states, ranging from 0.4 to 11/1,000 ticks (1 infected tick/90–2,174 collected) (1,8,10,11). We suspect the Virginia property was the likely location of infection, based on the number of ticks VDH collected while sampling an area that the patient frequented 10–14 days before symptom onset and because fewer ticks were collected from the Maryland property (Appendix).
The patient’s clinical and laboratory findings were consistent with HLH secondary to HRTV infection. HLH has been documented in several cases of infection with the related Bandavirus, severe fever with thrombocytopenia syndrome virus, and in at least 1 case of HRTV infection (1,4). Reports showed corticosteroids and ribavirin did not effectively treat severe fever with thrombocytopenia syndrome–triggered HLH, but preliminary clinical data shows potential benefit from favipiravir (1,15). Currently, clinical management for HRTV infection is supportive care (3).
We hypothesize that HRTV infection is underrecognized and mainly diagnosed when severe disease leads to additional testing at referral centers. Although lack of responsiveness to appropriate antimicrobial agents for bacterial tickborne illness might suggest severe disease (2), self-limited disease likely is undiagnosed or diagnosed as another tickborne disease.
Because tick ranges are increasing overall, incidence of previously regional tickborne infections, such as HRTV, likely will continue to increase. Expanding testing capabilities for arbovirus and tickborne infections, including multiplex testing, would enable real-time assessment and management of patients with potential arboviral and other tickborne infections.
About the Authors
Dr. Liu is an infectious disease fellow at the National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA. His research interest is in local, targeted antimicrobial therapy. Mr. Kannan is an MD candidate at the Johns Hopkins School of Medicine and a PhD candidate in the Johns Hopkins Department of Biomedical Engineering, Baltimore, Maryland, USA. His research interests include internal medicine and the interface of evidence-based medicine and patient-centered decision-making.
Since an ounce of prevention is worth a pound of doxycycline, the following CDC website offers advice on: Preventing Tick Bites.
