Western Encephalomyelitis Virus Infection in “Indicator” Chickens in Southern Alberta

Sera from indicator chicken flocks situated in southern Alberta near Lethbridge were tested by the hemagglutination-inhibition (HI) technique for antibodies to Western, Eastern and St. Louis Encephalitis viruses during the summer and early fall of the four years 1964 to 1967.

One chicken in 1964, 90 in 1965 and five each in 1966 and 1967 were positive to Western encephalomyelitis (WE) virus by hemagglutination-inhibition tests. All of the positive sera were confirmed by neutralization test (NT) in infant mice. No antibodies to the Eastern and St. Louis viruses were detected.

Infection with WE virus was detected in each of the four years, indicating that WE virus is endemic to southern Alberta with a marked seasonal incidence occurring between the second week in August and the third week in September.

An improved technique for filtering sera is described.

     

Epizootic of Western Encephalomyelitis Virus Infection in Equines in Alberta in 1965

The epizootic of equine encephalomyelitis in 1965 in Alberta was proved to be due to Western Encephalomyelitis virus infection by serological findings and virus isolations.

Sixty-three horses of 88 tested, showed a diagnostic rise of CF antibodies to Western Encephalomyelitis virus.

Western Encephalomyelitis virus was isolated from 5 brains of horses. Homologous antibodies were shown in 3 of these animals, the only ones from which blood specimens were received.

For the first time virological evidence is given that Western Encephalomyelitis virus infection in horses is found in more areas of Alberta and in regions situated further North than those previously suspected.

     

Why are simple control options for Toxocara vitulorum not being implemented by cattle and buffalo smallholder farmers in South-East Asia?

Toxocara vitulorum infection in large ruminants is endemic in many tropical countries and particularly in South-East Asia. A single treatment of calves with pyrantel at 14–21 days of age effectively controls the parasite. Despite this treatment being readily available, T. vitulorum infection remains common and widespread. To understand drivers of effective control of T. vitulorum infection, we examined treatment practices and knowledge of smallholder farmers of this parasite plus determined annual calf morbidity and mortality and identified potential risk factors for these estimates. Interviews were conducted with 273 smallholder farmers who had calves tested for T. vitulorum 4–6 months earlier. Reproductive rates of 0.6 and 0.4 calf per annum in cattle and buffalo respectively, and annual calf morbidity and mortality of 42.6% (CI 0.38–0.47) and 37.3% (CI 0.33–0.42) respectively, were identified. Interviewed farmers had either none (80.6%) or only minimal (19.4%) knowledge about T. vitulorum and only 2.5% of the farmers treated their calves for T. vitulorum using the recommended control regime. Multivariable logistic regression analyses with random effects showed that the number of adult cattle per household, T. vitulorum infection status of the household herd and farmer knowledge of T. vitulorum were significantly associated with calf morbidity and mortality. Financial analysis using partial budgeting showed a net benefit of USD 3.69, 7.46, 11.09 or 14.86 per calf when treating calves with pyrantel and attributing 25%, 50%, 75% or 100% of morbidity and mortality to T. vitulorum infection. The study identified that poor reproduction, high calf morbidity and mortality combined with very limited farmer knowledge and effective control of endemic Toxocariasis, contribute to suboptimal large ruminant production in mixed smallholder farming systems in South-East Asia. The large net benefit per calf achievable by a single pyrantel treatment should drive implementation of this intervention by smallholder farmers, especially as demand for livestock products continues to increase in this region and forces a change to more production oriented farming. To support this, continued capacity building that ensures knowledge transfer of best practice T. vitulorum control to smallholder farmers is required.     

Review of neurological diseases of ruminant livestock in Australia. VI: postnatal bovine, and ovine and caprine, neurogenetic disorders

This paper, the last in a series of reviews of neurological diseases of ruminants in Australia, discusses a range of neurogenetic disorders of cattle, sheep and goats, including necrotising encephalomyelopathy, glycogen storage disorders, cerebellar abiotrophy and β-mannosidosis. They are categorised by the species and breeds in which they occur.     

Neurological diseases of ruminant livestock in Australia. I: general neurological examination, necropsy procedures and neurological manifestations of systemic disease, trauma and neoplasia

Disease surveillance is an integral part of most veterinary practices in Australia. The aim of this series of invited reviews is to facilitate the differential and ultimately definitive diagnosis of some of the previously known, as well as the novel and emerging, neurological disorders of ruminant livestock, which is of particular importance in the surveillance for transmissible spongiform encephalopathies. General principles of a systematic neurological examination, necropsy procedures and the neurological manifestations of systemic disease, trauma and neoplasia are described here.