First Report of a Severe Outbreak of Aujeszky's Disease in Cattle in Sicily (Italy)

Abstract

Aujeszky's disease in cattle is caused by Suid herpes virus 1. The natural infection has been reported worldwide in bovine species and it is related to direct and indirect contact with infected pigs, which represent the main reservoir of the virus. Here, it is reported the first documented outbreak of Aujeszky's disease in cattle in Sicily (Italy). Severe itching and nonspecific neurological symptoms were the main reported clinical signs. No characteristic gross and histological features were reported other than cutaneous lesions caused by excessive pruritus and hyperaemia, haemorrhages and inflammation in the central nervous system. Diagnosis was confirmed by real time PCR and immunohistochemistry on the nervous tissue. The route of infection remained unknown, but serological data observed in pigs living in close cohabitation with cattle revealed a circulation of a wild strain of the virus in the area. This study contributes to a better knowledge of this disease in a non-conventional host and suggests the need to increase the prophylaxis control plans in specific breeding contexts.

Keywords: Aujeszky’s disease; Suid Herpesvirus 1; cattle; immunohistochemistry; outbreak; pseudorabies.

Figure 1

Farm structure. (a) animal distribution in the farm (pig-cattle breeding); Group 1: cattle kept in the barn; Group 2 cattle at pasture; the distribution of pigs (icons circled in blue) is identified both in the stable and in the pasture.; (b) close cohabitation between pigs (circled) and cattle (arrows) (group 1) in the barns and contamination of feeders by pigs; (c) pasture shared between pigs (circled in red) and cattle (group2).

Figure 2

Clinical manifestation of severe itching: (a) flank region (b) breast.

Figure 3

Posterior regions of the body where self-mutilation-induced trauma has occurred due to intense itching: (a) vulva (b) flank region and distal limbs.

Figure 4

Udder, auto-mutilation due to intense itching: (a,c) gross traumatic lesions, such as crusts, haemorrhagic suffusions and severe traumatic haemorrhage in the nipple; (b) Udder (itching area) HE 20×, severe necrosis of the epithelium; (d) Udder, HE 100× dermis, severe pyoderma and severe and diffuse necrotizing vasculitis.

Figure 5

Telencephalon: (a) Gross macroscopic evidence of hyperaemia of leptomeninges; (b) Telencephalon, HE 100×, serious scattered haemorrhages in the grey and white substance, minimal multifocal gliosis, minimal non-purulent perivascular sleeves.

Figure 6

Cord: (a) gross macroscopic evidence of hyperaemia of the spinal cord; (b) spinal cord HE 100×, serious scattered haemorrhages in the grey and white substance, minimal multifocal gliosis, minimal non-purulent perivascular sleeves; (c) spinal cord, HE 400×, gliosis in the white matter; (d) spinal cord, HE 200×, Immunohistochemistry with pool of three MAbs (clone 1F2, 2E12 and 3D5) multifocal granular SuHv-1 positivity in the cytoplasm of the neurons (arrow).

Figure 7

Phylogenetic tree based on partial sequencing of the UL44 gene. The tree was obtained using the maximum likelihood method and the HKY85 + I + G model with 1000 bootstrap replicates. The bootstrap percentage values are indicated at nodes. The Italian bovine sequenced are underlined.

Figure 8

Phylogenetic tree based on partial sequencing of the US8 gene. The tree was obtained using the maximum likelihood method and the HKY85 + I + G model with 1000 bootstrap replicates. The bootstrap percentage values are indicated at nodes. The Italian bovine sequenced are underlined.

Figure 9

The overall prevalence of Aujeszky’s disease in pigs in Sicily. To note the constant higher positivity rate registered in the Nebrodi park area when compared to the rest of the island and the average prevalence recorded in Sicily during the years to 2010 to 2019.