The annual incidence of campylobacteriosis — the most common cause of bacterial diarrheal illness in the United States — increased by 21% over 8 years, according to recent data. Researchers also reported an increasing number of Campylobacter outbreaks in the country, as well as isolates resistant to antibiotics.
The data indicate a need for nationwide surveillance of Campylobacter infections and assessment of risk factors, they wrote in Clinical Infectious Diseases.
“These data could be used as a comparison group to explore sources of infection among the groups identified in this study with the highest incidence or increasing incidence of infection,” study researcher Aimee L. Geissler, PhD, a CDC epidemiologist, and colleagues wrote. “In addition, increasing antimicrobial resistance among both domestic and travel-associated infections reinforces the need for responsible antibiotic use in both humans and animals.”
According to WHO, Campylobacter spp. is one of four key causes of diarrheal disease. Campylobacteriosis can be deadly for young children, older people and those who are immunosuppressed.
To assess its impact in the U.S., Geissler and colleagues consulted data from the Nationally Notifiable Disease Surveillance System, National Outbreak Reporting System, National Antimicrobial Resistance Monitoring System and Foodborne Diseases Active Surveillance Network.
They found 303,520 culture-confirmed cases of campylobacteriosis reported between 2004 and 2012. The disease’s annual incidence rate rose from 10.5 cases per 100,000 people in that period’s first 2 years to 12.7 cases per 100,000 in the last 2 years.
The rate was highest among children aged 4 years or younger (26.3 cases per 100,000), more than double the overall incidence rate. The greatest increase over the 8-year period was seen among people aged 60 years and older (42%), and it was more common among men than among women (12.63 per 100,000 vs. 10.08 per 100,000).
By geographic region, the rate of campylobacteriosis was highest in the West (16.18 per 100,000) and lowest in the South (6.79 per 100,000). However, the South had the largest increase from the study period’s first 2 years to the last 2 years (32%).
The rate also was higher in rural counties than in metropolitan counties (14.2 per 100,000 vs. 11.02 per 100,000), the researchers said.
They also compared rates of Campylobacter resistance to ciprofloxacin and erythromycin among 8,219 isolates. Altogether, 1,926 (23.4%) of them were resistant to ciprofloxacin, and 173 (2.1%) were resistant to erythromycin. A travel history was recorded for many isolates, showing that 1,070 were travel-associated and 4,793 were domestically acquired, the researchers said.
They compared resistance in the period of 2004 to 2010 with that in 2011 and 2012. Resistance of travel-associated isolates to ciprofloxacin increased from 60.2% to 67.5%, compared with an increase to the drug from 13% to 17% in domestic isolates. Resistance of travel-associated isolates to erythromycin increased from 3.6% to 6.8%.
The number of campylobacteriosis outbreaks also increased noticeably over the study period. From 2004 to 2006, an annual mean of 28 outbreaks with eight illnesses per outbreak occurred, the researchers said, compared with an annual mean of 56 outbreaks in 2010 to 2012, with five illnesses per outbreak.
The increased prevalence of campylobacteriosis in the U.S. calls for a new approach to controlling it, the researchers concluded.
“Our findings also underscore the importance of standardizing national surveillance for campylobacteriosis, which is important in understanding the burden of infection, better describing geographic variations and differences among species, elucidating risk factors and targeting prevention and control measures,” they wrote. – by Joe Green
Disclosure: The researchers report no relevant financial disclosures.