الخلاصة:
"Infectious causes of abortion have been associated with severe economic losses for the
livestock and have zoonotic implications. A cross-sectional study is carried out to estimate
prevalence of Chlamydia spp. antibodies and to investigate risk factors associated with
chlamydial infection in 552 ewes between March 2011 and January 2012. A serological
screening is conducted to determine prevalence of antibodies against five infectious agents in
226 ewes. ELISA, rapid slide agglutination and slow agglutination techniques are used to detect
antibodies against Chlamydia spp., Coxiella burnetii, Brucella melitensis, Salmonella abortus
ovis and Neospora caninum. Antibodies toward Chlamydia spp. and Coxiella burnetii were the
most prevalent. Anti-Chlamydia spp. and anti-C. abortus antibodies were present in respectively
24,5 % and 7,2 % of examined sera. Of the herds, 70,4 % had at least one seropositive animal for
Chlamydia spp. and 33,3 % for C. abortus. A pretested structured questionnaire was
administered in order to collect information on individual animal health and herd management
practices. Chi-square analysis and multivariable logistic regression model were used to identify
risk factors related to Chlamydia spp. and C. abortus seropositivity. Multivariable logistic
regression model identified 12-23 months age group and not using disinfectants as risk factors
for Chlamydia spp. seropositivity. Occurrence of stillbirth and 5–10 % mortality rate in young
lambs were significantly associated with Chlamydia spp. seropositivity. However, availability of
veterinary service was identified as a protective factor. The model revealed that foreign farm
visitors are a risk factor for enzootic abortion of ewes. Results of this study determined two
major variables associated with seropositivity to C. abortus; delivery of weak lambs and
septicemia in young lambs. Molecular characterization by PCR-RFLP of 104 fetal and placental
ovine samples confirmed infection with C. abortus in 4 placentas and 26 fetal tissues. The partial
nucleotide sequence similarity matrix of omp2 gene showed that the Algerian isolates have 96%
similarity with C. abortus FAS strain and 84.3 % similarity with C. caviae strain while a low
similarity the other species of the genus Chlamydophila was found. Histological examination of
PCR positive placentas revealed a severe placentitis."
