Sexual dimorphism in campylobacteriosis

Abstract

Sexual dimorphism in infectious diseases whereby disease incidence is more prevalent in one gender has been reported repeatedly in the scientific literature. Both behavioural and physiological differences have been suggested as a cause of this gender bias but there is a paucity of data to support either of these viewpoints. Here it is hypothesized that for campylobacteriosis physiological factors play an important role in the higher incidence in males. We demonstrate in the human population (from several countries in three continents) that this bias exists in young children (<1 year) where behavioural differences between genders are likely to be minimal. Further we demonstrate this difference in an animal model where both infection rates and shedding rates of the organism are greater in male mice.

Fig. 1

Sexual dimorphism of human campylobacteriosis averaged over the period 1997–2004 (error bars are standard errors of the mean, n=8 years) for (a) Canada (94 280 cases), (b) Grampian region of Scotland (5986 cases), (c) New Zealand (86 670 cases) and (d) Norway (18 202 cases).

Fig. 2

Colonization of male and female mice after oral administration of C. jejuni. (a) Faecal samples were collected at the indicated times and the number of c.f.u./g determined by plating in selective medium. (b) Four weeks after inoculation, mice were sacrificed and the number of c.f.u. in liver and intestine determined by plating in selective medium. The limit of detection was 10 bacteria.