Seroprevalence and molecular characterization of Chlamydia abortus in frozen fetal and placental tissues of aborting ewes in northeastern Algeria.

Enzootic abortion of ewes is one of the most serious health problems in sheep flocks worldwide. It has a significant economic impact because abortion, decrease in milk production and weak lambs. Besides, the bacteria is zoonotic. A cross-sectional study was conducted to determine the seroprevalence and risk factors associated with Chlamydia abortus infection in 552 ewes in Constantine using a C. abortus-specific indirect ELISA kit. Chlamydial DNA was investigated in ten ovine fetuses and eight placentas using PCR- restriction fragment length polymorphism (RFLP) and DNA sequencing. The study concluded that 7.2 % of ewes were seropositive and 33.3 % of sheep flocks had at least one seropositive ewe. Adjacent farmworker visits (OR = 7.667, 95 % CI (OR) = 2.307; 27.203) was defined as a risk factor. Deliveries of weak lambs (OR = 2.920, 95 % CI (OR) = 1.022; 8.342) and septicemia in lambs (OR = 9.971, 95 % CI (OR) = 2.383; 41.713) were significantly associated with chlamydial infection. PCR-RFLP analysis revealed positive signals to C. abortus in six fetuses and four placentas. Sequencing of the omp2 gene revealed that the Algerian strain is 96 % similar with C. abortus FAS strain. C. abortus plays a major role in abortion in northeastern Algeria. Appropriate control measures must be implemented to reduce economic losses and to avoid human contamination.