Campylobacter jejuni and Campylobacter coli: Dose Response Models

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Overview

Campylobacter are microaerophilic gram-negative curved or spiral rods with a polar flagellum. C. jejuni and C. coli are common causes of gastroenteritis [1]. It can cause acute self-limiting diarrhea in healthy humans with an incubation period of 2-3d, and appears very common worldwide. It is mainly a zoonosis, being primarily associated with birds (especially poultry). They do not grow in water and (like Escherichia coli) are an indicator of post-treatment contamination in water distribution systems.

According to feeding studies with chickens, strains of C. jejuni that have been passaged many times in the laboratory tend to have a lower ID50 than strains that are isolated from infected hosts and then used to infect new hosts, with minimal passage [2]. Minimally passaged strains also had more variation in ID50 [2]. Given safety concerns, strains used for human studies may be passaged and studied more, possibly underestimating infectiousness in actual human exposure scenarios [2].

Campylobacter epidemiology varies greatly between the developed and developing world, probably due to development of immunity early in life. Illness is rare after about 5 years of age (or earlier) in developing countries, but occurs among adults in industrialized countries, probably because they avoided exposure (and therefore immunity) in childhood [1]. However, immunity appears to protect against disease rather than infection, and asymptomatic shedding is common [1]. In a comparison of Mexican children <4 years of age and Swedish patients (ages not given), Swedish patients tended to carry only 1 Campylobacter serotype, while mixed serotypes were common among Mexican children (42%)[3]


References

  1. 1.0 1.1 1.2 Havelaar AH et al, (2009) Immunity to Campylobacter: its role in risk assessment and epidemiology. Critical Reviews in Microbiology. 35(1), pp.1-22. Full Text
  2. 2.0 2.1 2.2 Chen L et al., (2006) Dose response for infectivity of several strains of Campylobacter jejuni in chickens. Risk Analysis: An Official Publication of the Society for Risk Analysis. 26(6), pp.1613-1621. Full Text
  3. Sjögren E, Ruiz-Palacios G & Kaijser B, (1989) Campylobacter jejuni isolations from Mexican and Swedish patients, with repeated symptomatic and/or asymptomatic diarrhoea episodes. Epidemiology and Infection. 102(1), pp.47-57. Full Text