Invasive H. influenzae increased among older adults in Utah

Rubach MP. Emerg Infect Dis. 2011;doi:http://dx.doi.org/10.3201/eid1709.101991.

Issue: September 2011

The incidence of invasive Haemophilus influenzae has increased among adults in Utah, particularly among those aged at least 65 years, and was associated with increased mortality, according to new findings published in Emerging Infectious Diseases.

“Although the decrease in the overall incidence of invasive disease caused by Haemophilus influenzae type b for children and adults has been a remarkable public health success, changes in the epidemiology of invasive disease caused by other H. influenzae have been observed. The incidence of H. influenzae invasive disease has shifted toward adults,” Matthew P. Rubach, MD, of the division of infectious diseases at Duke University Medical Center, and colleagues wrote in the study.

The population-based study included 121 cases of invasive disease caused by typeable and nontypeable H. influenzae among adults residing in Utah aged 18 years and older between 1998 and 2008. The researchers assessed the epidemiology and outcomes of invasive disease cases.

Compared with an overall invasive disease incidence of 0.14/100,000 person-years in 1998, the overall incidence was 1.61/100,000 person-years in 2008 (P=.0023). Moreover, the incidence for invasive disease was significantly higher among those aged 65 years and older (2.74/100,000 person-years). This age group accounted for 51% of cases and 67% of deaths.

Invasive disease incidence was highest for nontypeable H. influenzae (0.23/100,000 person-years) and H. influenzae f (0.14/100,000 person-years).

No significant difference in incidence was observed between men and women (64 in women vs. 57 in men; P=.65). Most cases occurred during the winter (41.3%), followed by the spring (26.4%), fall (21.4%) and summer (10.7%).

Disclosure: The researchers report no relevant financial disclosures.

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