Congenital Tuberculosis in a Stillborn Calf

TL;DR

A stillborn calf was found to have congenital tuberculosis, showing how the disease can be passed from mother to fetus in cattle.

Contribution

This case report confirms in utero transmission of bovine tuberculosis in a calf through detailed diagnostic methods.

Findings

The stillborn calf showed typical tuberculosis lesions in the liver, spleen, and lymph nodes.

The isolated bacteria were confirmed as Mycobacterium bovis with spoligotype SB0140.

The dam tested positive for tuberculosis antibodies, supporting fetal infection.

Abstract

Bovine tuberculosis is a zoonotic infectious disease of cattle caused by the bacterium Mycobacterium bovis. In adult cattle, transmission is mainly via the respiratory route, whereas, in young calves, oral infection is also common. Congenital tuberculosis is rare. The purpose of this study was to describe in utero infection of a bovine stillbirth. The fetus was necropsied and tissue samples were processed for histopathology, bacteriology and PCR; a sample of the isolated strain was genotyped using spoligotyping. The whole herd was tuberculin skin tested and the dam’s serum was also assessed for the presence of antibodies against bovine tuberculosis with indirect ELISA. The macroscopic findings in different organs were consistent with tuberculosis. The histopathology demonstrated typical granulomatous lesions in the liver, spleen, hepatic and mediastinal lymph nodes. Acid-fast bacilli were observed in the smears stained using the Ziehl–Neelsen method. The colonies isolated were PCR-positive for IS6110 and the spoligotype corresponded to SB0140. The dam of the stillborn was positive for indirect ELISA and reacted to a single caudal skin test with bovine tuberculin. The fetal infection in utero with Mycobacterium bovis was confirmed through necropsy, histopathology and bacteriology, reinforcing the importance of testing young animals.

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