Detection of Toxoplasma gondii antigens reactive with antibodies from serum, amniotic, and allantoic fluids from experimentally infected pregnant ewes

Toxoplasma gondii, an intracellular protozoan parasite, is one of the major causes of infectious abortion in sheep. To further understand the pathogenesis of toxoplasmosis, serum, amniotic and allantoic fluids and foetal stomach contents were collected from experimentally infected pregnant ewes to determine pathogen numbers and other markers of infection. Fifteen pregnant ewes (90 days of gestation) were each orally inoculated with 3000 sporulated oocysts of T. gondii. Serum samples were collected weekly following challenge. Amniotic and allantoic fluids and foetal stomach contents were collected at 21, 25, 28, 33 and 35 days post-infection. Characteristic placental lesions were detected in 1 of 4 challenged ewes at day 25, 3 of 4 challenged ewes at day 28 and in all challenged ewes at days 33 and 35 post-infection. T. gondii was detected only sporadically in amniotic and allantoic fluids before 35 days of infection, by real-time PCR, and only in ewes with placental lesions. At 35 days post-infection, high numbers of parasite were detected in both amniotic and allantoic fluids. An increase in the number of fluids from challenged animals with IgM and IgG was detected over time, except for IgG in allantoic fluid, which was detected in all samples from day 21 post-infection. IgG in amniotic and allantoic fluids was shown to be specific for T. gondii, and reacted with antigens with an apparent molecular mass of approximately 22 kDa and 30 kDa. Results suggest a maternal source of immunoglobulin in the allantoic fluid and a foetal source of immunoglobulin in the amniotic fluid early in infection but that both sources may contribute immunoglobulin to both fluids at a later stage.     

Dairy science and health in the tropics: challenges and opportunities for the next decades

In the next two decades, the world population will increase significantly; the majority in the developing countries located in the tropics of Africa, Asia, Latin America, and the Caribbean. To feed such a population, it is necessary to increase the availability of food, particularly high-value animal protein foods produced locally, namely meat and dairy products. Dairy production in tropical regions has a lot of growth potential, but also poses a series of problems, particularly as dairy production systems were developed in temperate countries and in most cases are difficult to implement in the tropics. Drawbacks include hot weather and heat stress, the lack of availability of adequate feeds, poor infrastructure, and cold chain and the competition with cheap imports from temperate countries. This position paper reviews the major drawbacks in dairy production for the five major dairy species: cattle, water buffalo, sheep, goat, and camel, as well as the future trends in research and development. It also concerns the major trends in reproduction and production systems and health issues as well as environmental concerns, particularly those related to greenhouse gas emissions. Tropical Animal Health and Production now launches a topical collection on Tropical Dairy Science. We aim to publish interesting and significant papers in tropical dairy science. On behalf of the editorial board of the Tropical Animal Health and Production, we would like to invite all authors working in this field to submit their works on this topic to this topical collection in our journal.

     

Optimal management of a flammable multi-stand forest for timber production and maintenance of nesting sites for wildlife

Decline of cavity-using wildlife species is a major forest management issue. One of the causes of this problem is the loss in cavity tree abundance, resulting from short rotation silviculture, stand-replacing disturbance events and timber harvesting in disturbed stands. Cavity tree availability cannot be guaranteed due to the stochastic nature of disturbance events. We developed a Markov model to predict future cavity tree availability under alternative tree felling and fire protection strategies using information on cavity tree dynamics and fire history. Stochastic dynamic programming was used to find a strategy that maximizes timber revenues less forest management costs, including the cost of an artificial nest-box program that must be implemented whenever cavity trees become critically scarce. The requirement to implement a nest-box program in such circumstances strongly influenced the optimal tree felling strategy and resulted in a higher probability of having cavity trees in the future. This reflected an increase in the retention of old growth forest and stands with fire-killed cavity trees as well as stands of younger trees to provide a future source of cavities. These results demonstrate the need to consider the costs of artificial habitat enhancement and the risk of future cavity tree scarcity in multiple-use forest management planning.     

Regional patterns of nectar availability in subtropical eastern Australia

Context

There are few detailed data for short-term (≤?monthly) fluctuations in flowering and nectar availability at relatively large spatial scales. Such information is critical for understanding the governors of variation in flowering and for the management of floral resources assisting the persistence of nectar consumers in landscapes.

Objectives

To obtain monthly measurements of patterns of nectar availability in a 314,400 ha region, and to relate these patterns to potential environmental predictors.

Methods

Flowering was measured at 83 sites in natural vegetation and in eight domestic gardens in subtropical, eastern Australia. A nectar-availability index was developed was based on nectarivore visitation rates and plant-specific flowering patterns. Spatial–temporal patterns were related to environmental variables using boosted regression trees.

Results

The large between-year variation was due mostly to irregular flowering by several eucalypt species. There was a ‘lean season’ in the austral spring (August–September). Coastal vegetation was an important source of nectar for much of the year, including the lean season. Gardens produced prolific nectar throughout the year, peaking in August–October.

Conclusions

Nectar availability was most closely associated with primary productivity over the previous 12 months, average annual solar radiation, topographic wetness, and rainfall over the previous 6 months, although some relationships seemed counter-intuitive. There were large differences in nectar availabilities among broad vegetation types (especially rainforests vs. sclerophyllous forests), which partially accounted for the unintuitive results.

     

Short‐term incubation of equine laminar veins with cortisol and insulin alters contractility in vitro: possible implications for the pathogenesis of equine laminitis

This study investigated the effects of cortisol and insulin, hormones that affect both glycaemic status and vascular function, on the in vitro contractility of isolated healthy equine small laminar veins. Small veins (150–500 μm) draining the digital laminae from healthy horses or ponies were investigated by wire myography. Concentration response curves were constructed for noradrenaline (NA), phenylephrine (PE), endothelin‐1 (ET‐1) and 5‐hydroxytryptamine (5‐HT) in the presence of either cortisol (10^?6 m ) or insulin (1000 μIU/mL). Cortisol significantly increased the maximum contractility of laminar veins to the vasoconstrictors NA and 5‐HT but decreased the maximal contraction to ET‐1. Insulin decreased the contractility of vessels to PE and ET‐1. It is possible that short‐term cortisol excess could enhance venoconstrictor responses to 5‐HT and NA in laminar veins in vivo, thereby predisposing to laminitis. Additionally, a reduction in the ability of insulin to counteract alpha‐adrenoreceptor and ET‐1‐mediated contraction, likely to occur in subjects with insulin resistance, may further exacerbate venoconstriction in animals prone to laminitis. These mechanisms may also predispose horses with disorders such as equine Cushing's disease and equine metabolic syndrome to laminitis.     

Quantitative Risk Assessment for Zoonotic Transmission of Cryptosporidium parvum Infection Attributable to Recreational Use of Farmland

Cryptosporidiosis caused by Cryptosporidium parvum infection is a major cause of enteric illness in man and there is a significant reservoir in animals, particularly young ruminant species. To preliminary assess the magnitude of the risk posed by contact with faeces produced by infected livestock, two microbiological risk assessments have been developed: one for the risk of human infection with C. parvum while camping on contaminated land recently grazed by infected suckler cattle and a comparable risk assessment for camping on land recently spread with contaminated cattle slurry. Using a worst‐case scenario approach, the upper level of risk was estimated to be one infection in every 6211 person‐visits for a camping event on land recently grazed by infected cattle. Translated into camping events of 100 persons, this risk estimate would most likely lead to zero (98% likelihood) or one infection (1% likelihood). The results for cattle slurry model are similar despite different pathways. Sensitivity analysis was conducted for the grazing cattle model only. This suggested that the time between grazing and camping was the most important control strategy, but increasing hand‐washing frequency and the removal of cattle faeces before camping would also be beneficial. If the upper level of risk were to be judged unacceptable then further data would be required to more accurately estimate the risk of infection through these scenarios. Further research would also be required to assess the fraction of cases attributable to camping and/or environmental contact with Cryptosporidium oocysts.     

Successful surgical management of a medial humeral epicondyle fracture in a Thoroughbred foal

A 2-week-old 75 kg Thoroughbred filly was presented for the investigation of an acute forelimb lameness. Radiographs revealed a fracture of the medial epicondylar physis of the left humerus (Salter–Harris type II fracture). The fragment was removed via arthrotomy under general anaesthesia. Two months post-operatively, the foal was sound and at 2 years had resumed normal turn out. This case report describes a previously unreported surgical treatment for a fracture of the medial epicondylar physis in a foal.     

European consensus statement on leptospirosis in dogs and cats

Leptospirosis is a zoonotic disease with a worldwide distribution affecting most mammalian species. Clinical leptospirosis is common in dogs but appears to be rare in cats. Both dogs and cats, however, can shed leptospires in the urine. This is problematic as it can lead to exposure of humans. The control of leptospirosis, therefore, is important not only from an animal but also from a public health perspective. The aim of this consensus statement is to raise awareness of leptospirosis and to outline the current knowledge on the epidemiology, clinical features, diagnostic tools, prevention and treatment measures relevant to canine and feline leptospirosis in Europe.