1345. Invasive Disease caused by Haemophilus influenzae serotype a, an emerging pathogen in Alaska
Session: Oral Abstract Session: Respiratory Infections in Children
Saturday, October 22, 2011: 3:00 PM
Room: 156ABC
Background:  Prior to introduction of the Haemophilus influenzae type b (Hib) conjugate vaccines, rates of Hib disease among indigenous people living in Alaska (AK), especially western AK, were among the highest in the world. Routine Hib vaccination reduced these rates dramatically; however, invasive Haemophilus influenza type a (Hia) disease is increasingly being recognized in Alaska.  

Methods:  We identified cases of invasive Hi disease in AK from 1980–2010 through Alaska state-wide laboratory-based surveillance. Serotyping was performed by slide agglutination. Medical charts were reviewed using standardized forms to characterize clinical presentation.

Results:  During the study period, 1,190 cases of invasive Hi disease were reported, 28 (2.4%) of these were Hia; the first case identified occurred in 1999. From 1980-1998, none of the 21 encapsulated non-b Hi strains were Hia, compared to 28 of 61 (46%) isolated from 1999-2010 (p<0.001).  Median age of Hia cases was 0.8 year (range 0.3 - 74 years); 79% of cases occurred in children <5 years; 2 Hia cases in children < 1 year were fatal. The most common clinical presentations included: meningitis (36%), pneumonia (29%), and septic arthritis (7%).  Overall annual incidence (1999-2010) among children < 5 years of age was 4.4 per 100,000; 21 cases occurred in Alaska Native (AN) children (12.3 per 100,000) vs. 7 cases in non-AN children (1.5 per 100,000) (Risk Ratio = 2.9, p < 0.001). Ten cases occurred in western Alaska from December 2009 through December 2010 (in children < 5 years of age, a rate of 250 cases /105 population).

Conclusion: More than 10 years after introduction of Hib conjugate vaccine, Hia has emerged as a significant invasive bacterial disease in Alaska, with the highest rates among AN children. An evaluation of oropharyngeal carriage, transmission patterns and the potential role for chemoprophylaxis is underway.  Further research is needed to develop prevention strategies and investigate risk factors, regional differences in rates, severity of illness, and long term sequelae.


Subject Category: P. Pediatric and perinatal infections

Michael Bruce, MD, MPH1, Tammy Zulz, MPH1, Carolynn DeByle, BS1, Rosalyn Singleton, MD2, Debby Hurlburt, RN BSN1, Dana Bruden, MS1, Karen Rudolph, PhD1, Thomas Hennessy, MD MPH1, Joseph Klejka, MD3 and Jay Wenger, MD1, (1)Arctic Investigations Program, Centers for Disease Control and Prevention, Anchorage, AK, (2)Alaska Native Tribal Health Consortium, Anchorage, AK, (3)Yukon Kuskokwim Health Corporation, Bethel, AK

Disclosures:

M. Bruce, None

T. Zulz, None

C. DeByle, None

R. Singleton, None

D. Hurlburt, None

D. Bruden, None

K. Rudolph, None

T. Hennessy, None

J. Klejka, None

J. Wenger, None

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