Intra-uterine transmission of paratuberculosis (Johne's disease) in farmed red deer.
OBJECTIVE
To determine whether intra-uterine transmission of paratuberculosis (Johne's disease) occurs in farmed red deer (Cervus elaphus) in New Zealand.


METHODS
On four different farms, nine late-stage pregnant hinds with Johne's disease were slaughtered and samples were taken from them and their 10 fetuses. Samples of the hepatic, ileocaecal and mesenteric lymph nodes and the posterior ileum were collected from the hinds. The lung, liver, spleen, jejunum and ileum from the fetuses were sampled, as were the placentomes. Blood samples were tested using the 'Paralisa' test, a modified immunoglobulin G1 (IgG1) enzyme-linked immunosorbent assay (ELISA). Tissue samples were cultured using the BACTEC system, and fixed samples were sectioned and histological slides examined.


RESULTS
All nine hinds and 9/10 fetuses (one hind had twins) were culture-positive for Mycobacterium avium subsp paratuberculosis (M. ptb). Six hinds had gross lesions of Johne's disease, while all hinds had characteristic histopathological lesions affecting the ileum, ileocaecal valve and associated lymph nodes. The only histopathological change observed in the fetuses was some mild inflammation in the lungs of one individual. Acid fast organisms (AFOs) were seen in histological sections of the lymph nodes and ileum of six hinds, and none were seen in tissues from the fetuses. These six hinds were Paralisa-positive, whereas the remaining hinds and fetuses were serologically-negative.


CONCLUSIONS
These results confirm that there is a high risk of transmission of M. ptb from clinically affected hinds to their fetuses during pregnancy.


CONCLUSIONS
Johne's disease is an increasingly important disease responsible for deaths in young red deer. Recognising the influence of intra-uterine transmission on the spread of this disease may be an important step towards improved control of Johne's disease.
van Kooten
H C J
HC
Department of Farm Animal Health, Faculty of Veterinary Medicine, University of Utrecht, Yalelaan 1, De Uithof, 3584 CL Utrecht, Netherlands.
Mackintosh
C G
CG
Koets
A P
AP
D000818:Animals; D000829:Animals, Domestic / Q000382:microbiology; D001431:Bacteriological Techniques / Q000662:veterinary; D003670:Deer / Q000382:microbiology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D005333:Fetus / Q000382:microbiology*; D018445:Infectious Disease Transmission, Vertical / Q000662:veterinary*; D016927:Mycobacterium avium subsp. paratuberculosis / Q000302:isolation & purification*; D009520:New Zealand; D009928:Organ Specificity; D010283:Paratuberculosis / Q000635:transmission*; D011247:Pregnancy