Pathological and diagnostic investigations of abortions and neonatal mortality associated with natural infection of Brucella abortus in dromedary camels

Abstract

Brucellosis is a significant zoonotic disease that is emerging or reemerging in many parts of the world. This study was carried out to diagnose and investigate the pathological lesions associated with Brucella abortus in the fetuses and placenta of naturally infected dromedary camels. For diagnosis, the blood samples from infected dams were subjected to Rose Bengal Plate Test (RBPT) and blood PCR. The placental and fetal lung tissue samples were subjected to pathological examination and PCR. Nine cases of abortions and one case of early neonatal mortality was reported in the infected camels. The hematological parameters in infected dams revealed anemia and leukocytosis. The important pathological lesions in the infected fetuses were subcutaneous edema, moderate amount of serohemorrhagic fluid in the body cavities, interstitial pneumonia, degenerative changes in the liver, severe congestion with mononuclear infiltration in the kidney, and congestion in other visceral organs. The placentas were thickened, edematous, and showed necrosis along with mononuclear infiltration in histopathology. The RBPT and PCR for placental and fetal lung tissues detected all ten cases positive for B. abortus infection. However, blood PCR was positive only in two pregnant camels. The findings of the study indicated that B. abortus infection in pregnant dromedary camels causes necrotizing placentitis and fetal pneumonia resulting into abortion during mid to last trimester of pregnancy. The RBPTwas found to play an important role in early serological diagnosis, whereas PCR was useful in confirmatory diagnosis of brucellosis from placental and fetal lung tissue samples.