Case Report: Congenital tuberculosis in an aborted dromedary camel fetus

Abstract

Tuberculosis (TB) is a serious public health problem worldwide, especially in tropical developing countries. Nevertheless, reports on congenital TB in humans and animals are extremely rare. In this study, abortion was reported in an 8-year-old she-camel at the 9th month of gestation. The she-camel appeared healthy in clinical examination, had a good body condition score, normal appetite, and had no signs of respiratory disease and fever. The expelled placenta was dark red-colored, thickened, and edematous with multifocal to coalescing ecchymotic hemorrhages on the allantoic surface. The striking finding was multiple, white-yellow, solid nodular lesions in the fetal lung, the pleura, and the liver. On histopathology, typical granulomatous lesions were detected in the lung and the liver characterized by caseous necrosis surrounded by lymphocyte and macrophage infiltration and concentric layers of fibrosis. The Ziehl-Neelsen staining detected scarce acid-fast bacilli in lung and liver tissues. The DNA extracted from tubercular lesions from the lung and liver showed amplification of the IS6110 region of the Mycobacterium tuberculosis complex by PCR. The sequencing and phylogenetic analysis revealed a close association of these sequences with Mycobacterium tuberculosis. The she-camel was detected positive for a single intradermal tuberculin test performed 24 h after abortion. This is the first report on congenital TB caused by M. tuberculosis in a dromedary camel fetus with a possible vertical transmission.

Keywords: Mycobacterium tuberculosis; abortion; camel; congenital tuberculosis; pathology; vertical transmission.

Figure 1

(A) Placenta showing edema and a large area of ecchymotic hemorrhage (arrow) on the allantoic surface. (B) Fetal lung showing congestion and multiple yellow-white tubercle nodules scattered throughout its surface (arrow). (C) Enlarged and congested fetal liver showing multiple yellow-white tubercle nodules (black arrow). Also, note multiple tubercle nodules adhered to the inner surface of the thoracic cavity (white arrow).

Figure 2

(A) HE-stained lung section showing granuloma with mineralization and caseous necrosis (arrow) surrounded by scattered lymphocyte and macrophage infiltration, and concentric layers of fibrosis. HE x 100. (B) HE-stained liver section showing dark blue areas of mineralization (arrow) and macrophage and fibrous tissue infiltration. HE x 200.

Figure 3

(A) HE-stained lung section showing scattered macrophages (black arrow), few lymphocytes, and a multinucleate giant cell (filled arrow). HE x 400. (B) ZN-stained section of liver showing sparse acid-fast bacilli (arrow). ZN x 1,000.