Herd-level risk factors for Cryptosporidium infection in dairy-goat kids in western France

We conducted a cross-sectional study of risk factors for herd-level kid positivity for Cryptosporidium parvum oocysts in dairy-goat farms (Deux-Sèvres, western France). From January to March 2003, faeces from a convenient sample of 879 5- to 30-day-old goat kids from 60 herds were examined microscopically after staining with carbol fuschin. Oocyst shedding was scored semi-quantitatively (0 to 4+) allowing us to obtain a cumulative score per herd. Standardized questionnaires with information about management practices were collected in each farm. We found positive kids in 32 of 60 herds (53.3%) and in 142 animals out of 879 (16.2%). We used logistic regression for two risk-factor model: (1) simple positive (case: herd score ≥1+, at least one positive kid in the herd, versus control: herd score = 0), (2) strongly positive (case: overall herd score ≥3+ versus control: herd score <3+). Risk factors associated with simple positive herds were period of sampling compared to the peak of births (After versus Before, OR = 4.2, 95% CI 1.2, 15.3) and practice of kid grouping by age or weight (Yes versus No, OR = 4.4, 95% CI 1.0, 19.1). Risk factors associated with strongly positive herds were period of investigation (February/March versus January, OR = 12.7, 95% CI 2.1, 76.6), exposure to graminaceous plants in forage (OR = 11.6, 95% CI 1.7, 81.0) and type of ventilation in the goat premises (Vertical versus Wind effect, OR = 14.7, 95% CI 2.1, 106.1). No important association was found between kid-management practices and herd positivity. These results suggest a major role of the environment of kids during their first hours of life in the adult-goat premises regarding the transmission of C. parvum infection.