Krimpsiekte in South Africa : historical perspectives

Krimpsiekte, also known as cotyledonosis or nenta in sheep and goats, has been recognised as a disease entity since 1775. However, it was only in 1891 that Veterinary Surgeon Soga reproduced the condition by dosing Cotyledon (= Tylecodon) ventricosus leaves to goats. Professor MacOwan, a botanist, confirmed the identity of these nenta plants. From a South African veterinary toxicological point of view the date 1891 is of considerable historical significance as this was the first time that a plant was experimentally demonstrated to be toxic to livestock in South Africa. A chronological account of the history of krimpsiekte research is provided.Faculty of Veterinary Science, University of Pretoria.http://www.jsava.co.zaam2014mn201

Potential health risks posed by plant-derived cumulative neurotoxic Bufadienolides in South Africa

Bufadienolide-type cardiac glycosides have a worldwide distribution and are mainly synthesized by plants, but there are also animal sources. In South Africa, members of three genera of the Crassulaceae (Cotyledon, Tylecodon and Kalanchoe) cause a unique chronic form of cardiac glycoside poisoning, predominantly in small stock. This paretic/paralytic condition is referred to as “krimpsiekte”, cotyledonosis or “nenta”. “Krimpsiekte” is a plant poisoning only reported from South Africa and is regarded as the most important plant poisoning of small stock in the semi-arid Little Karoo and southern fringes of the Great Karoo. The toxicosis is caused by cumulative bufadienolides which have neurotoxic properties. Four types of cumulative neurotoxic bufadienolides, namely cotyledoside, and the tyledosides, orbicusides and lanceotoxins, have been isolated. Based on the structure activity relationships and certain toxicokinetic parameters possible reasons for their accumulation are presented. Consumption of edible tissues from animals that have ingested these plants poses a potential risk to humans.http://www.mdpi.com/journal/moleculesam2016Paraclinical Science

Multimycotoxin analysis of South African Aspergillus clavatus isolates

Aspergillus clavatus poisoning is a neuromycotoxicosis of ruminants that occurs sporadically across the world after ingestion of infected feedstuffs. Although various toxic metabolites are synthesized by the fungus, it is not clear which specific or group of mycotoxins induces the syndrome. A. clavatus isolates were deposited in the culture collection of the Biosystematics Division, Plant Protection Research Institute, Agricultural Research Council during incidences of livestock poisoning (1988–2016). Six isolates were still viable and these plus three other South African isolates that were also previously deposited in the collection were positively identified as A. clavatus based on morphology and ß-tubulin sequence data. The cultures were screened for multiple mycotoxins using a liquid chromatography-tandem mass spectrometric (LC-MS/MS) method. Twelve A. clavatus metabolites were detected. The concentrations of the tremorgenic mycotoxins (i.e., tryptoquivaline A and its related metabolites deoxytryptoquivaline A and deoxynortryptoquivaline) were higher than patulin and cytochalasin E. Livestock owners should not feed A. clavatus-infected material to ruminants as all the South African A. clavatus isolates synthesized the same compounds when cultured under similar conditions.The National Research Foundation of South Africa (Grant number 103747).https://link.springer.com/journal/125502019-05-01hj2018Paraclinical Science

Fusarium species isolated from Pennisetum clandestinum collected during outbreaks of kikuyu poisoning in cattle in South Africa

Kikuyu poisoning occurs sporadically in South Africa. It is of major economic importance, as valuable dairy cows are often poisoned by it, and once affected, the mortality rate is high. Pennisetum clandestinum samples were collected during eight outbreaks of kikuyu poisoning in cattle in the Eastern Cape Province of South Africa from 2008 to 2010. The kikuyu grass samples were submitted specifically for the isolation and molecular identification of Fusarium species, as it was recently suggested that mycotoxins synthesised by Fusarium torulosum could be the cause of this intoxication. Ninety-four Fusarium isolates were retrieved from the grass samples, of which 72 were members of the Fusarium incarnatum/Fusarium equiseti species complex based on morphology and phylogenetic analyses of the translation elongation factor 1α sequence data. The South African isolates from kikuyu identified as members of the F. incarnatum/F. equiseti species complex grouped together in six separate clades. The other isolates were Fusarium culmorum (n = 3), Fusarium redolens (n = 4) and Fusarium oxysporum (n = 15). Although F. torulosum could not be isolated from P. clandestinum collected during kikuyu poisoning outbreaks in South Africa, the mycotoxicosis theory is still highly plausible.National Research Foundation (NRF)http://www.ojvr.orgtm201

Lead ingestion as a potential contributing factor to the decline in vulture populations in southern Africa

Vulture populations in southern Africa have been on the decline for years, which unlike the Asian vulture crisis, has no one specific cause. Reasons attributable are deliberate and secondary poisonings, drowning, power line injuries, electrocutions, traditional medicine ("muti" trade) and calcium deficiencies. However, lead toxicity as a potential causal factor is hardly mentioned. The potential for lead toxicity needs to be considered as substantial game hunting occurs in the region with little regulatory control on bullet types. In this study, we determined the whole blood lead concentrations of captive and wild vulture populations in South Africa and Namibia (n=185). Results were compared to previous published ranges indicative of background exposure (<10μg/dL), non-toxic point exposure based upon the range established from captive birds and subclinical exposure. In general, whole blood lead concentrations were higher for wild African White-backed vultures (Gyps africanus)(AWBV) than Cape vultures (G. coprotheres)(CGV) at 15.54±12.63μg/dL vs 12.53±8.88μg/dL (non-significantly different), while in the Bearded vultures (Gypaetus barbatus) no indication of exposure was evident. Very similar exposures resulted irrespective of the birds being in captivity or under wild, free-roaming conditions. A proportion of wild birds did, however, appear to be exposed to another source of lead than purely environmental (±12% and 30.6% for AWBV and CGV respectively). One bird, which had a whole blood concentration of 100μg/dL, died soon after capture. To find the relationship between whole blood lead concentration and likely exposure factors, birds were compared by their rural/urban location, vicinity to mines and surrounding soil lead concentrations. With no relationship being present for the latter factors, we believe that this is evidence that the portion of southern African vultures being exposed to unknown source of lead, which we suggest arises from leaded ammunition remaining from hunting.Afgri via the WWF (GT 1456 - VULTURE CHEMICALS THREATS PROJECT) and the Ernst Oppenheimer Trust.http://www.elsevier.com/locate/envres2018-01-31hb2017Paraclinical Science

Distinguishing between toxic and non-toxic pyrrolizidine alkaloids and quantification by liquid chromatography-mass spectrometry

Pyrrolizidine alkaloids (PAs) are important plant toxins causing poisoning in livestock, leading to significant financial and production losses each year. It may also enter the human food chain as contaminants of grains, via animal products such as milk, eggs and honey or herbal remedies. Not all PAs are toxic and it is important to be able to distinguish between toxic and non-toxic PAs. We developed a sensitive and selective analytical method to determine toxic 1,2-unsaturated PAs concentrations in plant extracts by liquid chromatography–mass spectrometry (LC–MS) with electrospray ionization and precursor ion experiments. Multi-reaction-mode experiments were used to quantify the concentrations of the different unsaturated PAs and results were expressed as mg/g retrorsine equivalents. The results obtained on Crotalaria sphaerocarpa contaminating maize crops have important implications.National Research Foundation.http://www.elsevier.com/locate/phytol2015-05-31hb201

Putative neuromycotoxicoses in an adult male following ingestion of moldy walnuts

A tremorgenic syndrome occurs in dogs following ingestion of moldy walnuts, and Penicillium crustosum has been implicated as the offending fungus. This is the first report of suspected moldy walnut toxicosis in man. An adult male ingested approximately eight fungal-infected walnut kernels and after 12 h experienced tremors, generalized pain, incoordination, confusion, anxiety, and diaphoresis. Following symptomatic and supportive treatment at a local hospital, the man made an uneventful recovery. A batch of walnuts (approximately 20) was submitted for mycological culturing and identification as well as for mycotoxin analysis. Penicillium crustosum Thom was the most abundant fungus present on walnut samples, often occurring as monocultures on isolation plates. Identifications were confirmed with DNA sequences. The kernels and shells of the moldy walnuts as well as P. crustosum isolates plated on yeast extract sucrose (YES) and Czapek yeast autolysate (CYA) agars and incubated in the dark at 25 °C for 7 days were screened for tremorgenic mycotoxins and known P. crustosum metabolites using a liquid chromatography-tandem mass spectrometric (LC-MS/MS) method. A relatively low penitrem A concentration of only 1.9 ng/g was detected on the walnut kernels when compared to roquefortine C concentrations of 21.7 μg/g. A similar result was obtained from P. crustosum isolates cultured on YES and CYA, with penitrem A concentrations much lower (0.6–6.4 μg per g mycelium/agar) compared to roquefortine C concentrations (172–1225 μg/g). The authors surmised that besides penitrem A, roquefortine C might also play an additive or synergistic role in intoxication of man.This work is based on research supported in part by the National Research Foundation of South Africa (grant number 103747).https://link.springer.com/journal/125502020-02-01hj2019Paraclinical Science

What is in a name? Scientific name changes of potentially poisonous plants and fungi in South Africa

This brief review is dedicated to the memory of Johannes (Hans) Vahrmeijer (1942/10/25–2021/07/17). Hans Vahrmeijer was a qualified botanist with a keen interest in poisonous plants. In 1981, he published an illustrative guide ‘Poisonous plants of southern Africa that causes stock losses’, Tafelberg Publishers.Changes over the past five decades in the scientific names of some potentially poisonous plants and toxigenic fungi in South Africa are briefly reviewed. Some of the reasons why taxonomists change names are highlighted. In recent years, DNA sequencing data have contributed considerably towards establishing phylogenetic relationships among plants, often resulting in changes in generic circumscription and, consequently, the names of species. Philosophical differences between the phylogenetic and the evolutionary schools of plant classification are briefly explained as these may manifest as different classifications for the same group of plants. Although choice of classification remains the prerogative of the end-user of plant names, in this review, the classifications for plants currently adopted by the South African National Biodiversity Institute (SANBI) in its online database, Plants of Southern Africa (POSA), were followed. Noteworthy generic changes include Pachystigma to Vangueria, Homeria to Moraea, and Urginia to Drimia. Following much controversy, the species native to southern Africa that were formerly treated as Acacia are now classified in either Vachellia or Senegalia, with the genus name Acacia being retained for the mainly Australian members of the group, the latter commonly known as wattles. Former southern African members of Acacia implicated in poisoning include Vachellia erioloba (camel thorn), Vachellia sieberiana var. woodii (paperbark thorn), and Senegalia caffra (common hook thorn).http://www.jsava.co.zahttp://www.ville-ge.ch/musinfo/bd/cjb/africa/index.phpam2023Paraclinical SciencesPlant Production and Soil Scienc

Plant poisonings in livestock in Brazil and South Africa

Information on intoxication of livestock by plants in Brazil, in terms of cause, clinical signs and pathology, is compared with information on livestock poisoning by plants in South Africa. Plant poisoning, including mycotoxicosis, is considered to be one of three major causes of death in livestock in Brazil, which is one of the top beef producing countries in the world, with a cattle population of more than 200 million. Cattle production in South Africa is on a more modest scale, but with some 600 species of plants and fungi known to cause toxicity in livestock, as opposed to some 130 species in Brazil, the risk to livestock in South Africa appears to be much greater. The comparisons discussed in this communication are largely restricted to ruminants.http://www.jsava.co.zaam201

Confirmed organophosphorus and carbamate pesticide poisonings in South African wildlife (2009–2014)

During a six-year period (from January 2009 to December 2014), specimens collected from 344 cases of suspected organophosphorus and carbamate pesticide poisonings in wildlife, including birds, were submitted to the Toxicology Laboratory (ARC-OVI) for analysis. A positive diagnosis was made in 135 (39%) of these cases. The majority of cases were from birds, which included Cape vultures (Gyps coprotheres) and African white-backed vultures (Gyps africanus) and bateleur eagles (Terathopius ecaudatus). In one incident 49 vultures were killed when a farmer intentionally laced carcasses with carbofuran in an attempt to control jackal predation. There were 22 incidents of poisoning in helmeted guineafowl (Numida meleagris). On nine different occasions blue cranes (Anthropoides paradiseus) were poisoned, in one incident 14 birds were reported to have been killed. Over the period of investigation, there were 20 cases of poisoning involving mammalian species, the majority being vervet monkeys (Chlorocebus pygerythrus). The carbamate pesticides were responsible for 57 incidents of poisoning. Aldicarb, carbofuran and methomyl were detected in 26, 18 and 12 cases respectively. The majority of organophosphorus pesticide poisonings were caused by diazinon (n = 19), monocrotophos (n = 13) and methamidophos (n = 10).http://www.jsava.co.zaam201