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Disease surveillance in England and Wales, August 2020

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APHA disease Surveillance report headlines

  • Cerebrocortical necrosis in dairy cows

  • Alert for myiasis caused by the spotted flesh fly

  • Mycoplasma hyosynoviae arthritis in replacement gilts

  • Cataracts in broiler breeders

  • Focus on negated bluetongue virus cases in small ruminants

Highlights from the scanning surveillance network


Polioencephalomalacia/cerebrocortical necrosis in dairy cows

Acute onset blindness, staggering and ataxia, leading to recumbency, were reported in a 26-month-old dairy cow that had calved three months previously. The animal was on a diet of grass and receiving 2 kg per day of concentrate.

The cow was euthanased and its head was submitted for examination. This revealed changes affecting the brain; the cerebral gyri were swollen and there was generalised slight yellowing and also mild coning of the cerebellum. A minimal autofluorescence of the cerebral hemispheres was observed when the brain was viewed under ultraviolet light.

Histopathology confirmed lesions of polioencephalomalacia or cerebrocortical necrosis (CCN). From the history of sudden-onset nervous signs, the fact that the cows were at pasture, the recent very dry weather and the time of year, it was considered highly likely that the cause was vitamin B1 deficiency.

About this report

This report is produced each month by the APHA Surveillance Intelligence Unit and the six Species Expert Groups (livestock and wildlife). The international horizon-scanning summaries are produced by the Defra/APHA International Disease Monitoring (IDM) team, notifiable disease reports by the APHA Veterinary Exotic and Notifiable Disease Unit (VENDU), and threat analysis by the cross-agency Veterinary Risk Group (VRG). The report is drawn from scanning surveillance information, data and reports produced by the APHA veterinary investigation centres and non-APHA partner postmortem examination providers contributing to the Veterinary Investigation Diagnosis Analysis (VIDA) database and complying with standardised diagnostic and laboratory testing criteria. Other livestock and wildlife scanning surveillance reports may also be found at

One other cow in the herd was affected a few days later and was reported to respond positively …

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