Hepatogenous photosensitisation in cows grazing turnips (Brassica rapa) in South Africa

Holstein cows on a farm in the Humansdorp district, Eastern Cape province, South Africa, developed reddened, painful teat skin 3 days after grazing a mixed forage crop dominated by bulb turnip (Brassica rapa, Barkant cultivar). The crop was grazed 45 days after planting and 10% of the herd developed symptoms. More characteristic non-pigmented skin lesions started manifesting 1–2 days after the appearance of the teat lesions. Affected cows had elevated serum activities of gamma-glutamyl transferase, glutamate dehydrogenase and aspartate aminotransferase. These blood chemistry findings confirmed a secondary (hepatogenous) photosensitivity. As a result of the severity of the teat and skin lesions, seven cows were slaughtered and tissue samples from five of them were collected for histopathological examination. Liver lesions in cows that were culled 3 or more weeks after the onset of the outbreak showed oedematous concentric fibrosis around medium-sized bile ducts and inflammatory infiltrates in portal tracts. Characteristic lesions associated with other known hepatobiliary toxicities were not found. No new cases were reported 5 days after the cattle were removed from the turnips. The sudden introduction of the cows, without any period of transitioning or adaptation to grazing turnips, as well as the short latent period, clinical signs of photosensitisation, blood chemistry and histopathology, confirmed a diagnosis of Brassicaassociated liver disease, a condition seen in New Zealand but not previously described in South Africa. Brassica forage crops are potentially toxic under certain conditions and farmers must be aware of these risks.http://www.jsava.co.zaam2022Paraclinical Science

West Nile virus in wildlife and nonequine domestic animals, South Africa, 2010–2018

West Nile virus (WNV) lineage 2 is associated with neurologic disease in horses and humans in South Africa. Surveillance in wildlife and nonequine domestic species during 2010–2018 identified WNV in 11 (1.8%) of 608 animals with severe neurologic and fatal infections, highlighting susceptible hosts and risk for WNV epizootics in Africa.The work was funded through the US Centers for Disease Control and Prevention’s Global Disease Detection grant for zoonotic arboviruses under grant 1U19GH000571-01-GDD Non-Research CoAg with the National Health Laboratory Services project 23 and University of Pretoria Zoonotic Arbo and Respiratory Virus Group income-generated funds. J.S. received doctoral scholarships from the National Research Foundation (grant no. 95175), the Meat Industry Trust (grant no. IT8114/98), and the Poliomyelitis Research Foundation (grant no. 15/112) and a partial studentship from the US Centers for Disease Control and Prevention Cooperative Agreement no. 5 NU2GGH001874-02-00 with the University of Pretoria.http://wwwnc.cdc.gov/eidam2020Medical Virolog

Mortality in East African shorthorn zebu cattle under one year : predictors of infectious-disease mortality

BACKGROUND: Infectious livestock diseases remain a major threat to attaining food security and are a source of economic and livelihood losses for people dependent on livestock for their livelihood. Knowledge of the vital infectious diseases that account for the majority of deaths is crucial in determining disease control strategies and in the allocation of limited funds available for disease control. Here we have estimated the mortality rates in zebu cattle raised in a smallholder mixed farming system during their first year of life, identified the periods of increased risk of death and the risk factors for calf mortality, and through analysis of post-mortem data, determined the aetiologies of calf mortality in this population. A longitudinal cohort study of 548 zebu cattle was conducted between 2007 and 2010. Each calf was followed during its first year of life or until lost from the study. Calves were randomly selected from 20 sub-locations and recruited within a week of birth from different farms over a 45 km radius area centered on Busia in the Western part of Kenya. The data comprised of 481.1 calf years of observation. Clinical examinations, sample collection and analysis were carried out at 5 week intervals, from birth until one year old. Cox proportional hazard models with frailty terms were used for the statistical analysis of risk factors. A standardized post-mortem examination was conducted on all animals that died during the study and appropriate samples collected. RESULTS: The all-cause mortality rate was estimated at 16.1 (13.0-19.2; 95% CI) per 100 calf years at risk. The Cox models identified high infection intensity with Theileria spp., the most lethal of which causes East Coast Fever disease, infection with Trypanosome spp., and helminth infections as measured by Strongyle spp. eggs per gram of faeces as the three important infections statistically associated with infectious disease mortality in these calves. Analysis of post-mortem data identified East Coast Fever as the main cause of death accounting for 40% of all deaths, haemonchosis 12% and heartwater disease 7%. CONCLUSION: The findings demonstrate the impact of endemic parasitic diseases in indigenous animals expected to be well adapted against disease pressures. Additionally, agreement between results of Cox models using data from simple diagnostic procedures and results from post-mortem analysis underline the potential use such diagnostic data to reduce calf mortality. The control strategies for the identified infectious diseases have been discussed.The Wellcome Trust (grant No. 079,445)http://www.biomedcentral.com/1746-6148/9/175am2013ab201

Parasite co-infections and their impact on survival of indigenous cattle

In natural populations, individuals may be infected with multiple distinct pathogens at a time. These pathogens may act independently or interact with each other and the host through various mechanisms, with resultant varying outcomes on host health and survival. To study effects of pathogens and their interactions on host survival, we followed 548 zebu cattle during their first year of life, determining their infection and clinical status every 5 weeks. Using a combination of clinical signs observed before death, laboratory diagnostic test results, gross-lesions on post-mortem examination, histo-pathology results and survival analysis statistical techniques, cause-specific aetiology for each death case were determined, and effect of co-infections in observed mortality patterns. East Coast fever (ECF) caused by protozoan parasite Theileria parva and haemonchosis were the most important diseases associated with calf mortality, together accounting for over half (52%) of all deaths due to infectious diseases. Co-infection with Trypanosoma species increased the hazard for ECF death by 6 times (1.4–25; 95% CI). In addition, the hazard for ECF death was increased in the presence of Strongyle eggs, and this was burden dependent. An increase by 1000 Strongyle eggs per gram of faeces count was associated with a 1.5 times (1.4–1.6; 95% CI) increase in the hazard for ECF mortality. Deaths due to haemonchosis were burden dependent, with a 70% increase in hazard for death for every increase in strongyle eggs per gram count of 1000. These findings have important implications for disease control strategies, suggesting a need to consider co-infections in epidemiological studies as opposed to singlepathogen focus, and benefits of an integrated approach to helminths and East Coast fever disease control.The Wellcome Trust (grant No. 079445)http://www.plosone.orgam201

(3,5,7-Tribromotropolonato-κ2O,O′)tris(triphenylphosphine-κP)silver(I)

The title compound, [Ag(C7H2Br3O2)(C18H15P)3], a silver(I) derivative of 3,5,7-tribromotropolone, has three triphenylphosphine ligands coordinated to the silver centre, whereas the 3,5,7-tribromotropolonate anion coordinates as a bidentate ligand. The compound is an example of a five-coordinate silver complex containing a bidentate ligand