Influence of dipping practices on the seroprevalence of babesiosis and anaplasmosis in the foot-and-mouth disease buffer zone adjoining the Kruger National Park in South Africa

A serological survey of bovine babesiosis and anaplasmosis was conducted in the foot-and-mouth disease buffer zone surrounding the Kruger National Park in South Africa between 2001 and 2003 to determine whether the withdrawal of government-subsidized dipping in certain regions had affected the seroprevalence of these tick-borne diseases. Seroprevalence of Anaplasma marginale and Babesia bovis increased during the study period. This increase was greater in Limpopo Province where farmers had to supply their own acaricide than in Mpumalanga Province where dipping materials were provided by the local Veterinary Services. The number of animals testing positive for B. bigemina decreased in both provinces during the study period, which was attributed to possible vector displacement rather than more effective tick control measures. Responses to a questionnaire on ticks and tick-borne diseases revealed local knowledge on the subject to be highly variable and sometimes incorrect.     

Dermatosparaxis in two Limousin calves

Background

An unusual presentation of skin disease was identified in two related neonatal Pedigree Limousin calves presented to University Veterinary Hospital, University College Dublin, following detailed post mortem examination a diagnosis of dermatosparaxis was made. Dermatosparaxis in animals or Ehlers Danlos Syndrome, which is the analogous condition seen in humans, is a connective tissue disorder characterised by extreme skin fragility. To the authors’ knowledge this is the first report of such a diagnosis in the Limousin breed and the features of this lethal phenotype were severe in comparison to previous reports of the condition.

Case presentation

Two calves, which were full siblings, a pedigree Limousin bull (Calf A) and pedigree Limousin heifer (Calf B) were examined clinically after presenting collapsed since birth, both had grossly abnormal skin with multiple skin fissures visible and both calves were subsequently euthanised. Both calves underwent gross post mortem examination, after which histological samples were reviewed and electron microscopical examination of selected skin samples was carried out. Histological features of dysplastic dermal collagen were identified. The diagnosis of dermatosparaxis in the Limousin breed was confirmed. Genetic testing was conducted to determine if the current cases had the same mutation as has previously been described in Belgian Blue cattle. Some common parentage was traced but genetic testing did not show a similar mutation to that previously described in cattle. The specific genetic cause in this case is unknown.

Conclusions

This is the first report of dermatosparaxis in the Limousin and the presentation of the dermatosparaxis phenotype has some noteworthy features thus further genetic testing is required to pinpoint the causative mutation or other genetic defect. Given the popularity of the breed and the lethal nature of the phenotype in this case it is important to raise awareness of the condition.

     

Degradation parameters of amaranth,barley and quinoa in alpacas fed grass hay

This study was conducted to determine the compartment 1 (C1) characteristics of alpacas (fistulated male, 7 ± 1.5 years old, 61 ± 5 kg BW) fed grass hay (GH) supplemented with amaranth (AM), quinoa (Q) and barley (B) grains. Alpacas were provided water ad libitum while housed in metabolism crates. The GH and GH plus treatments were fed at 0700 every day. Treatment periods were for 14 days in which GH or GH plus one of the grain treatments were randomly allocated. On day 14, volatile fatty acids (VFA), pH and ammonia nitrogen (NH₃‐N) were determined at 1, 3, 6, 10, 14, 18 and 24 h post‐feeding. C1 degradation of each feed component was also determined with the alpacas being fed GH only and the samples incubated for 0, 2, 4, 8, 14, 24, 48 and 72 h. Dry matter (DM), neutral detergent fibre (NDF) and crude protein (CP) were determined and were divided into three categories: a = immediately soluble; b = the non‐soluble but degradable; and u = non‐degradable/unavailable, potential extent of degradation (PE), degradation rate (c) and effective degradation (ED). C1 passage rate was determined using acid detergent insoluble ash as a marker and was calculated to be 5.5%?h‐1. Total DM intake was highest (p < 0.05) for B and resulted in a higher (p < 0.05) CP intake. GH and AM were different in mean pH (6.81 and 6.66, respectively). B NH₃‐N was greater (p < 0.05) than the other treatments. Total VFA was greatest (p < 0.05) for AM, with the greatest composition differences being a shift form acetate percentage to butyrate. DM, NDF and CP degradation was different across the treatments, where PE and ED were higher (p < 0.05) for the grain treatments. The pseudo‐grains AM and Q had similar C1 degradation characteristics to B.     

Strain and dose infectivity of Vibrio parahaemolyticus: the causative agent of early mortality syndrome in shrimp

Diseases of shrimp have contributed to billions of dollars of economic loss in the aquaculture industry. Newly emerging strains of the bacterium Vibrio parahaemolyticus produce a condition in shrimp called early mortality syndrome or acute hepatopancreatic necrosis disease. Three different V. parahaemolyticus strains were evaluated for their respective pathogenicity on shrimp, Litopenaeus vannamei, when the bacterial strains were grown under various laboratory conditions prior to inoculating shrimp. For each trial, feed was inoculated with a known concentration of bacteria and then fed to the shrimp. The early mortality syndrome strain of V. parahaemolyticus was the most lethal resulting up to 100% mortality within 24 h after being introduced to shrimp via a single feeding. The other two strains of Vibrio, one isolated from the environment and the other from a human clinical case, resulted in 0% and 30% mortality within 96 h respectively. The concentration of the early mortality syndrome strain of V. parahaemolyticus that the shrimp were exposed to directly correlated with mortality rate, which allowed for lethal or sublethal short‐term disease challenge assays to be established. Infiltration of haemocytes was also evident in the midgut caeca of shrimp infected with the early mortality syndrome strain of V. parahaemolyticus, which has not been previously reported.     

Phytotoxins from the leaves of Laggera decurrens.

Upon biological screening of a series of African medicinal plants, substantial phytotoxic activity was found in the leaves of Laggera decurrens (Vahl.) Hepper & Wood (Asteraceae), using a Lemna minor bioassay. Bioassay-guided fractionation of the leaves led to the isolation of two physiologically active compounds: 3-hydroxythymoquinone and 5-acetoxy-2-hydroxythymol, causing death of Lemna minor in the 25-100 microM range. Symptoms were a rapidly developing chlorosis, followed by necrosis of fronds. The compounds also inhibited growth and germination of the grass weed Agrostis capillaris down to 250 microM. The mode of action of both compounds could not be elucidated, but they do not appear to be photosystem II inhibitors.