680. Cluster of Epstein-Barr Virus-Associated Hemophagocytic Lymphohistiocytosis Los Angeles, 2010
Session: Abstracts: Virology
Friday, October 22, 2010
Background: Acquired hemophagocytic lymphohistiocytosis (HLH) is a disorder of macrophage activation associated with infections including Epstein-Barr virus (EBV). Although >90% of adults have latent EBV infection, EBV-associated HLH is rare and often fatal. We report a cluster of 3 adults with EBV-associated HLH diagnosed in a 3 month period. Because incidence of HLH in the US has not been described, we reviewed International Classification of Diseases (ICD)-9 coded discharge data for HLH in Los Angeles County (LAC).

Methods: We defined EBV-associated HLH according to Histiocyte Society 2004 criteria for HLH among persons with active EBV infection (positive EBV IgM serology or EBV DNA polymerase chain reaction [PCR] >5 copies/mL). To identify HLH patients at Hospital A, we searched for ICD-9 code 288.4 usage during January 2007–March 2010. To estimate the baseline rate of ICD-9 coded acquired HLH in LAC, we examined all hospital discharges during 2007–2008 (2009–2010 data not available) for patients aged =15 years with code 288.4.

Results: During 1/2010–3/2010, we identified 3 patients with EBV-associated HLH at Hospital A. The rate of EBV-associated HLH in 2010 was significantly higher than for 2007–2009 (4.9 versus 0.14/10,000 Hospital A discharges, respectively; P = .0017). Patients were males ages 23–33 years. Peak EBV level by quantitative PCR was 501–28,000 copies/mL. Two patients were treated with ganciclovir and the investigational HLH 2004 protocol, one of whom is alive at 1 month after treatment; the third died before treatment. We estimate 0.9 cases of ICD-9 coded HLH annually/million persons in LAC (Table 1).

Table 1. ICD-9 coded discharges for HLH among persons aged ≥15 years at hospitals in LAC, 2007–2008.

                                             2007         2008           Mean

No. ICD-9–coded HLH cases      3              10              

LAC population aged ≥15 years 7,532,106 7,663,168 

Rate/1,000,000 persons           0.40         1.30            0.9

Conclusion: Acquired HLH is rare. We identified a cluster of EBV-associated HLH at a single facility.  We estimate 9 adults are newly diagnosed with HLH/year in LAC. This is the first epidemiologic investigation of an HLH cluster in the US.


Subject Category: V. Virology including clinical and basic studies of viral infections, including hepatitis

Speakers:
Theodoros Kelesidis, MD , Ronald Reagan UCLA Medical Center, Los Angeles, CA
Dawn Terashita, MD, MPH , Department of Public Health, Los Angeles County Acute Communicable Disease Control Program, Los Angeles, CA
David A. Pegues, MD , Medicine - Infectious Diseases, David Geffen School of Medicine at UCLA, Los Angeles, CA

Disclosures:

T. Kelesidis, None

D. Terashita, None

D. A. Pegues, None

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