Leptospira interrogans serovar icterohaemorrhagiae seropositivity and the reproductive performance of sows

The reproductive performance of 28 sows seropositive to Leptospira interrogans serovar icterohaemorrhagiae was compared with that of 87 Leptospira sp. seronegative dams belonging to the same herd. Sows were sampled during 1988 to 1993. During this period the herd was not submitted to any kind of intervention (antibiotic therapy, immunoprophylaxis or rodent control). Relative risks (RR) of return to heat, mummified fetuses, stillbirth, and weak newborn piglets for infected sows were assessed and the differences in means of total piglets born per litter, piglets born alive, piglets effectively housed, weaned piglets, stillbirths, mummified fetuses, weak newborn piglets, weight at birth of the piglets effectively housed, weight at 21 days of life and weight at weaning were evaluated. Seropositive dams had a greater risk of having weak newborn piglets (RR = 1.67, 1.02 < or = CI 95% < or = 2.72) and also of having more weak newborn piglets per litter (P = 0.01). Other variables examined were not different (P > 0.05).