Tuberculosis in kudus (Tragelaphus strepsiceros) in the Kruger National Park

Five kudus (Tragelaphus strepsiceros), three bulls and two cows, within the Greater Kruger National Park complex, were diagnosed with generalized tuberculosis caused by Mycobacterium bovis. The lesions seen in these animals were similar to those previously reported in kudus and included severe tuberculous lymphadenitis of the nodes of the head and neck (that resulted in noticeable uni- or bilateral swelling beneath the ear), thorax, and the mesentery. All the animals also suffered from severe granulomatous pneumonia. The lesions in the lungs were more severe cranially and had a miliary distribution elsewhere in the lungs. Based on the DNA patterns of the M. bovis isolates, at least some of these kudus were infected with strains commonly present in tuberculous buffaloes, lions, cheetahs, and baboons in the Park whereas other strains from these kudus were quite different and may reflect another source of infection. The presence of tuberculous kudus in the Park is expected to complicate control measures that may be instituted to contain or eradicate the disease in the Park.

Tuberculosis, caused by Mycobacterium bovis, in a kudu (Tragelaphus strepsiceros) from a commercial game farm in the Malelane area of the Mpumalanga Province, South Africa

Tuberculosis, caused by Mycobacterium bovis, was diagnosed for the first time, in a kudu cow from a commercial game ranch in the Malelane area of the Mpumalanga Province close to the Kruger National Park. This diagnosis has important implications for the eradication of the disease in commercial and communal livestock in the area. Kudus are considered to be a potential maintenance host and, because of discharging fistulae in the parotid area where the lymph nodes are commonly infected, they have the potential of disseminating bacteria over wide areas. Cognisance should be taken of the presence of tuberculosis in a species other than domesticated cattle in this area and its implications for the control of tuberculosis in cattle.

The epidemiology of tuberculosis in free-ranging African buffalo (Syncerus caffer) in the Kruger National Park, South Africa

The presence of bovine tuberculosis (Mycobacterium bovis) in the Kruger National Park (KNP) was determined for the first time in 1990. It was diagnosed in an African buffalo (Syncerus caffer) bull, which was found recumbent and in an emaciated and moribund state near the south-western boundary fence. This prompted an investigation into the bovine tuberculosis (BTB) status of the KNP, with emphasis on its epidemiological determinants and risk factors. This report documents the findings of surveys that were conducted from 1990 to 1996. It was found that BTB had entered the KNP ecosystem relatively recently (+/- 1960), and has found favourable circumstances for survival and propagation in a fully susceptible and immunologically naive buffalo population. Indications are that it entered the KNP from across the southern river boundary, where the presence of infected domestic cattle herds had been documented. From there the infection spread through the southern buffalo population and is currently spreading in a northward direction. It was estimated that this northward spread took place at a rate of about 6 km per year; the prospect being that, if this rate of spread is maintained, the entire KNP may be affected in less than 30 years from now. Spillover from buffalo had already occurred in species such as chacma baboon (Papio ursinus), lion (Panthera leo), cheetah (Acinonyx jubatus), kudu (Tragelaphus strepsiceros) and leopard (Panthera pardus). Although there is no indication yet that these species act as maintenance hosts, the possibility is raised that these, or an as yet overlooked species, might assume such a role in future. In the KNP, BTB manifests itself as a chronic and predominantly subclinical disease in buffalo. It may take years for clinical signs to develop, and then only at a terminal stage, when emaciation is a constant feature. It is suspected that the time from infection to death is variable and dependent on the animal's immune response, which can be weakened by such factors as stress, old age or droughts. It was found that, in the interim, buffalo have a normal reproductive life. On necropsy, buffalo show almost exclusively lung and upper respiratory tract involvement, pointing to an aerogenous mode of transmission. Histologically, little sign of encapsulation of lesions was detected, which suggests that they are exceptionally susceptible to BTB and that most lesions are open and infectious and progressive, leading ultimately to death of the individual. Evidence also indicates that BTB is progressive within the herd context (92% being the highest prevalence rate thus far determined in a buffalo herd) as well as progressive within the KNP buffalo population (the implication being that virtually all buffalo herds in the KNP will eventually be infected). Preliminary data suggest a positive correlation between disease prevalence and mortality, with potential mortality reaching up to 10% in buffalo herds having BTB prevalence rates of 50 % and higher. Only the future will tell what the effect of the disease on the population dynamics of buffalo will be.

Prevalence of bovine tuberculosis in African buffalo at Kruger National Park

Bovine tuberculosis (BTB) was first detected in Kruger National Park (KNP) in a single African buffalo (Syncerus caffer) in 1990. In 1991/1992, 2,071 African buffalo were examined for BTB as part of a culling program that removed animals from all known herds in KNP. The prevalence of BTB in 1991/1992 was estimated to be 0%, 4.4% (+/-0.6%), and 27.1% (+/-1.4%), in the north, central, and south zones of KNP, respectively. In 1998, a stratified, two-stage cluster sampling method was used to estimate that the prevalence of BTB was 1.5% (+/-2.5%), 16% (+/-5.3%), and 38.2% (+/-6.3%), in the north, central, and south zones, respectively. This represented a significant increase in prevalence (P < or = 0.05) in the south and central zones, but not in the north zone. Continued monitoring of BTB in KNP is important for understanding disease transmission risks, potential population effects, and the efficacy of disease management strategies. The methodology and sample sizes used in 1998 are appropriate for future BTB monitoring in KNP.

Toxicological effects in rats chronically fed low dietary levels of fumonisin B(1)

The toxicity of low dietary levels of fumonisin B(1) (FB(1)), i.e. 1, 10 and 25 mg FB(1)/kg diet, were monitored in rats over a period of 24 months. No effects on the body weight gain and feed intake profiles were noticed, while the relative liver weight was significantly (P<0.05) reduced in the FB(1)-treated rats. Mild toxic effects, including single cell necrosis (apoptosis), proliferation of bile duct epithelial cells (DEC), and early signs of fibrosis, bile duct hyperplasia and in one case, adenofibrosis, were noticed in the liver of the rats fed the highest (25 mg/FB(1)/kg diet) dietary level. A significant (P<0.05) increase in the level of oxidative damage was also noticed in the liver of the rats of high dosage dietary group. The toxic effects were less severe in the 10 mg FB(1)/kg dietary group, whilst only a few ground glass foci were observed in the 1 mg FB(1)/kg dietary group. Hepatocyte nodules, staining positively for glutathione-S-transferase (placental form, PGST), were observed macroscopically in the 25 mg FB(1)/kg treated group and to a lesser extent in the 10 mg FB(1)/kg treated rats. The most prominent toxic lesions by FB(1) (10 and 25 mg FB(1)/kg dietary groups) in the kidneys were restricted to the tubular epithelium manifesting as granular cast, necrosis, apoptosis, calcification and the presence of regenerative foci in the proximal convoluted tubules. The existence of a cytotoxic/proliferative threshold with respect to cancer induction by FB(1) in rat liver became apparent, with a dietary level of <10-mg FB(1)/kg diet as a no effect threshold for the induction of hepatocyte nodules.

The rise and fall of tuberculosis in a free-ranging chacma baboon troop in the Kruger National Park

A single troop of free-ranging chacma baboons (Papio ursinus) was found to be infected with tuberculosis caused by Mycobacterium bovis. It is assumed that some members of the troop originally became infected when feeding on a tuberculous carcass in the veld or on tuberculous material scavenged at a nearby post mortem facility. Subsequently, apparent aerosol transmission took place while sleeping in an unused room. Oral transmission probably also occurred due to continuous contamination of the floor of this room and the common, narrow access (a train bridge crossing the Sabi River) to it with faeces and urine. A macroscopic prevalence of 50 % was found and the disease was noted to progress rapidly in infected baboons. A variety of organs had typical tuberculous lesions, of which the spleen, lungs and mesenteric lymph nodes were consistently, grossly affected. Using Restriction Fragment Length Polymorphism analysis, all but one of the baboon isolates were found to be identical to the most common African buffalo (Syncerus caffer) isolate (genotype 1) in this Park. The opportunistic sleeping facility was made inaccessible to the troop, which was forced to revert to sleeping in trees. A follow-up survey six months after closure, demonstrated that the disease had disappeared from the troop, and that no spillover infection had occurred into neighbouring troops.

Selected chemical parameters in the blood and metals in the organs of the Nile crocodile, Crocodylus Niloticus, in the Kruger National Park

Healthy and sick crocodiles of varying sizes were examined from the Olifants River in the central part of the Kruger National Park, the Sabi River in the southern part and the Shingwedzi River in the northern region. Blood was collected for the determination of certain parameters and samples of fat, muscle, kidney and liver tissue were collected and analyzed for their heavy metal content. The results of the blood analyses are within the range recorded in the literature, but the metal analyses were inconclusive as similar data are not available for comparison. The results of the metal analyses are presented here for use as baseline and reference data.

Diseases of captive cheetahs (Acinonyx jubatus jubatus) in South Africa: a 20-year retrospective survey

As part of an ongoing study to determine the basis for high prevalences of veno-occlusive disease, glomerulosclerosis, and chronic lymphoplasmacytic gastritis in cheetahs, a retrospective pathology survey of captive cheetahs in the Republic of South Africa (RSA) was conducted. The RSA population was selected because its genetic composition and captive management were similar to those of the cheetah population in U.S. zoos, in which these diseases are common. For this study, archived pathology materials at the University of Pretoria Faculty of Veterinary Sciences in Onderstepoort and the Faculty of Veterinary Science, MEDUNSA, from 69 cheetahs that died between 1975 and 1995 were reviewed, and prevalences of common lesions were compared with those in the U.S. population. Gastritis associated with Helicobacter-like organisms was the most prevalent disease, accounting for close to 40% of the mortalities, including several cheetahs < 3 yr old. Glomerulosclerosis and veno-occlusive disease also were major causes of mortality in RSA cheetahs. RSA cheetahs also had adrenal cortical hyperplasia, cardiac fibrosis, lymphocytic depletion of the spleen, systemic amyloidosis, and splenic myelolipomas. The presence in the captive RSA cheetah population of the same unusual diseases that are common in U.S. cheetahs suggests a species predilection to develop these diseases in captivity.

Tuberculosis in Kafue lechwe (Kobus leche kafuensis) and in a bushbuck (Tragelaphus scriptus) on a game ranch in central province, Zambia

Mycobacteriosis was diagnosed for the first time outside a national park in free-ranging wild animals on a game ranch in Zambia. A Kafue lechwe (Kobus leche kafuensis) was found dead with tuberculous lesions on a ranch near Lusaka. Acid-fast bacilli were found in the affected organs. Mycobacteria were isolated from these tissues. A bushbuck (Tragelaphus scriptus) was found dead on the same ranch with multiple superficial abscesses in the neck region, extensive granulomatous lesions in the lung, the bronchial and mediastinal lymph nodes and several nodular lesions in the spleen. Few acid-fast bacilli were found in the exudate from the abscesses and lesions in the affected organs. Histologically the lesions resembled those of tuberculosis, but mycobacteria could not be isolated. In addition, 1 Kafue lechwe among 37 wild ungulates of 13 species shot on the ranch showed typical tuberculous lesions in the lungs, but the diagnosis was not confirmed by bacterial isolation. The role of the Kafue lechwe as maintenance host for tuberculosis as well as in the possible spread of this disease to other wildlife are discussed.

Parafilariosis in African buffaloes (Syncerus caffer)

This is the first report on the occurrence of Parafilaria bassoni in the African buffalo (Syncerus caffer). Previously this parasite has been recorded only in springbok (Antidorcas marsupialis) in Namibia. Haemorrhagic perforations (bleeding points), the usual lesions seen in infected animals, were caused by gravid female parasites ovipositing embryonated eggs. These lesions occurred mainly on the dorsal and lateral sides of buffaloes. Complications of these lesions developed in a small number of buffaloes because of secondary bacterial infection [subcutaneous abscesses (3/178)] and as a consequence of a localized Type 1 hypersensitivity [large cutaneous ulcers (7/178)]. Red-billed oxpeckers (Buphagus erythrorynchus) appeared to play an important role in the epidemiology of this parasite as well as in the pathogenesis of the lesions. They reduced the likelihood of spread by ingesting blood containing embryonated eggs, and caused the development of large ulcers by feeding on superficial necrotic skin. From the results of an ELISA test it was determined that P. bassoni-infected buffaloes occur throughout the Kruger National Park complex, with a seroprevalence of approximately 34%.

The cancer-promoting potential of fumonisin B1 in rat liver using diethylnitrosamine as a cancer initiator

The cancer-promoting potential of fumonisin B1 (FB1) was investigated by feeding different dietary levels (10, 50, 100, 250, 500 mg FB1/kg) to diethynitrosamine (DEN)-initiated rats for 21 days. Dietary levels containing 50 mg FB1/kg and higher, markedly increased the number and size of the placental form of glutathione-S-transferase-positive (GSTP+) foci in the liver of the rats. The cancer-promoting activity of FB1 was associated with an inhibitory effect on partial hepatectomy (PH)-induced regenerative hepatocyte proliferation, as the incorporation of 3H-labelled thymidine was significantly (P < 0.05) reduced by those FB1-containing diets that exhibited cancer promotion. In vitro studies on the mitogenic activity of epidermal growth factor (EGF) in primary rat hepatocytes further supported the in vivo data in that FB1, similar to other cancer promoters such as phenobarbital and 2-acetylaminofluorene (2-AAF), alters growth stimulatory responses in primary hepatocytes. No significant (P > 0.05) changes in the sphinganine/sphingosine (Sa/So) ratio were observed in the liver of the rats fed the lowest FB1-containing diet (50 mg FB1/kg diet) that effected cancer promotion. The present study indicated that FB1 exhibited cancer-promoting activity in the absence of adverse hepatotoxic effects and at dietary levels that failed to effect cancer initiation.

Tuberculosis in buffaloes (Syncerus caffer) in the Kruger National Park: spread of the disease to other species

Tuberculosis, caused by Mycobacterium bovis, was recently diagnosed in a cheetah (Acinonyx jubatus), two lions (Panthera leo) and a chacma baboon (Papio ursinus) from the Kruger National Park (KNP). It is assumed that they contracted the disease directly or indirectly from tuberculous buffaloes in the park. Tuberculous granulomatous lesions in the lungs were extensive and constituted the predominant changes in all three animal species. These pulmonary lesions included tuberculous bronchiolitis and cavitation which would facilitate dissemination of M. bovis into the environment. Spread of the disease to free-ranging species (in which it has not previously been reported) that may act as maintenance hosts of the infection, is a matter of serious concern.

An outbreak of bovine tuberculosis in a free-living African buffalo (Syncerus caffer--sparrman) population in the Kruger National Park: a preliminary report

Bovine tuberculosis was diagnosed for the first time in an African buffalo (Syncerus caffer) in the Kruger National Park (KNP). The index case was a 2-year-old, emaciated bull which had been found recumbent and obviously ill, near the south-western boundary of the KNP, in July 1990. During a follow-up random sampling of 57 buffalo, from two herds in close proximity to this initial case, nine more suspect cases were found. Mycobacterium bovis was isolated from a lung and thoracic lymph node, respectively, of two of these cases. Histopathologically, all nine of these animals had granulomatous lesions compatible with a diagnosis of mycobacteriosis, but acid-fast organisms could be demonstrated in only one animal.

An outbreak of encephalomyocarditis-virus infection in free-ranging African elephants in the Kruger National Park

A cluster of four deaths in late December 1993, marked the onset of an outbreak of disease of African elephants (Loxodonta africana) in the Kruger National Park (KNP) in South Africa, which has an estimated population of 7,500 elephants. Mortalities peaked in January 1994, with 32 deaths, and then declined steadily to reach pre-outbreak levels by September, but sporadic losses continued until November. During the outbreak altogether 64 elephants died, of which 53 (83%) were adult bulls. Archival records revealed that, in addition to the usual losses from known causes such as poaching and intraspecific fighting, sporadic deaths from unexplained causes had, in fact, occurred in widely scattered locations from at least 1987 onwards, and from that time until the perceived outbreak of disease there had been 48 such deaths involving 33 (69%) adult bulls. Carcases had frequently become decomposed or had been scavenged by the time they were found, but seven of eight elephants examined early in 1994 had lesions of cardiac failure suggestive of encephalomyocarditis (EMC)-virus infection, and the virus was isolated from the heart muscles of three fresh carcases. The results of tests for neutralizing antibody on 362 elephant sera collected for unrelated purposes from 1984 onwards and kept frozen, indicated that the virus had been present in the KNP since at least 1987. Antibody prevalences of 62 of 116 (53%) 18 of 139 (13%) and seven of 33 (21%) were found in elephants in three different regions of the KNP in 1993 and 1994. Studies had been conducted on myomorph rodents in the KNP for unrelated purposes since 1984, and trapping attempts were increased during the perceived outbreak of disease in elephants. There was a striking temporal correlation between the occurrence of a population explosion (as evidenced by markedly increased catch rates per trap-night) and a surge in prevalence of antibody to EM virus in rodents, and the occurrence of the outbreak of disease in elephants.

Advanced tuberculosis in an African buffalo (Syncerus caffer Sparrman)

A necropsy conducted on an emaciated 8-year-old female African buffalo (Syncerus caffer) in the Kruger National Park, revealed gross pathological changes compatible with generalised bovine tuberculosis. Macroscopic lesions in the lungs and associated lymph nodes were of a caseous necrotic nature with liquefied foci. Mycobacterium bovis was cultured from pulmonary lesions. The distribution and the characteristics of the lesions are described and the conclusion is made that the initial route of infection was aerogenous with secondary bacterial metastasis to the intestine. It would also appear that the spread of infection within the animal was extremely rapid. The conjecture is made that due to the cavernous state of the pulmonary lesions, the animal was probably highly infective at the time of death. Environmental factors that may have had an influence on the pathogenesis of the disease are seasonal rainfall fluctuations, extreme temperature variations and harsh ultra-violet exposure.

Clinical and histological comparison of tissue damage and healing following incisions with the CO2-laser and stainless steel surgical blade in dogs

The tissue damage and subsequent healing of skin, linea alba and intestinal wall incisions made with a CO2-laser and a stainless steel surgical blade were evaluated clinically and histologically in dogs (n = 10). The amount of blood lost in each type of skin incision was measured by taking the pre- and postoperative mass of surgical swabs. The tissues were sutured and the skin incisions examined every day. The animals were subsequently euthanased (Day 12) and all incisions examined histologically. A delay in the healing process was observed in the laser incisions of the skin during the first 4 d, but there was no difference in the healing rate of the intestinal wounds or of the linea alba. The blood loss due to the laser incisions was significantly less than that caused by the surgical blade. It was concluded that the CO2-laser can be used with confidence when incising the skin and intestine and that, due to its precision, the surgical blade is by far a more accurate method to incise the linea alba.

Atherogenic effects in a non-human primate of Fusarium moniliforme cultures added to a carbohydrate diet

Adding less than 0.5% w/w of culture material of strain MRC 826 of the fungus Fusarium moniliforme to a carbohydrate diet low in fat resulted in an atherogenic plasma lipid profile in a non-human primate. Simultaneously increased plasma fibrinogen and activity of blood coagulation factor VII could enhance atherogenesis. This unique potential for promotion of atherosclerosis was probably secondary to chronic hepatotoxicity as indicated by liver fibrosis and elevated cholesterol, albumin and the enzymes AST, ALT, LD, GGT and ALP in serum. The cholesterol and enzymes responded in proportion to the calculated doses of fumonisin mycotoxins in the F. moniliforme MRC 826 cultures. Fumonisins are water soluble and heat stable. Thrombotic, hepatotoxic, carcinogenic and cerebral effects of MRC 826 culture material and fumonisins are well known in non-primates. The estimated fumonisin concentrations tested fall within a range due to natural contamination of human foods. The results suggest that all maize grain products should be analysed for fumonisins.

Toxicity and carcinogenicity of the Fusarium moniliforme metabolite, fumonisin B1, in rats

A semi-purified corn-based diet containing 50 mg/kg of pure (not less than 90%) fumonisin B1 (FB1), isolated from culture material of Fusarium moniliforme strain MRC 826, was fed to a group of 25 rats over a period of 26 months. A control group of 25 rats received the same diet without FB1. Five rats from each group were killed at 6, 12, 20 and 26 months. The liver was the main target organ in the FB1-treated rats and the hepatic pathological changes were identical to those previously reported in rats fed culture material of F.moniliforme MRC 826. All FB1-treated rats that died or were killed from 18 months onwards suffered from a micro- and macronodular cirrhosis and had large expansile nodules of cholangiofibrosis at the hilus of the liver. Ten out of 15 FB1-treated rats (66%) that were killed and/or died between 18 and 26 months developed primary hepatocellular carcinoma. Metastases to the heart, lungs or kidneys were present in four of the rats with hepatocellular carcinoma. No neoplastic changes were observed in any of the control rats. Chronic interstitial nephritis was present in the kidneys of FB1-treated rats killed after 26 months. No lesions were observed in the esophagus, heart or forestomach of FB1-treated rats and this is contrary to previous findings when culture material of the fungus was fed to rats. It is concluded that FB1 is responsible for the hepatocarcinogenic and the hepatotoxic but not all the other toxic effects of culture material of F.moniliforme MRC 826 in rats.

A craniopharyngioma in a seven-year-old dog

A seven-year-old male Border Collie was presented with a history of lethargy, episodic circling, incoordination and polydypsia. Physical examination revealed depression, obesity and bradycardia. A neurological examination indicated the possible presence of a space-occupying lesion in the brain. Results of the clinical investigation revealed hyposthenuria, sinus bradycardia and increased concentration of protein in the cerebrospinal fluid. A computerised axial tomography scan revealed a mass in the region of the hypophysis. The dog was euthanased and a post mortem examination confirmed the presence of a craniopharyngioma.

Distemper-like disease and encephalitozoonosis in wild dogs (Lycaon pictus)

Clinical signs of a fatal disease resembling those of canine distemper were observed in two groups of captive wild dog (Lycaon pictus) pups 13 days after vaccination with a commercially available combination vaccine for dogs which contained a live attenuated strain of canine distemper virus. Histopathological examination of tissues revealed the presence of intranuclear inclusion bodies in neurons and lesions resembling canine distemper as well as colonies of an Encephalitozoon sp. in the central nervous system and kidneys. Lesions were observed in both organs which resembled those described in other species infected with Encephalitozoon cuniculi.

Fumonisins--novel mycotoxins with cancer-promoting activity produced by Fusarium moniliforme

Cultures on corn of Fusarium moniliforme MRC 826 are known to cause leukoencephalomalacia in horses and to be toxic and hepatocarcinogenic in rats. Culture material of this F. moniliforme isolate has also been shown to exhibit cancer-promoting activity in a short-term cancer initiation-promotion bioassay with diethylnitrosamine-initiated rats and the induction of gamma-glutamyl-transpeptidase-positive (GGT+) foci as an endpoint after 4 weeks of promotion. This bioassay was used as a monitoring system to isolate cancer-promoting compounds from cultures of F. moniliforme MRC 826. Culture material was successively extracted with ethyl acetate and CH3OH-H2O (3:1). Most of the cancer-promoting activity was recovered in the CH3OH-H2O extract and remained in the aqueous phase following partitioning of this extract between CH3OH-H2O (1:3) and CHCl3. The CH3OH-H2O fraction was chromatographed on an Amberlite XAD-2 column, and the active fraction was eluted with CH3OH. This fraction was chromatographed on a silica gel column with CHCl3-CH3OH-CH3COOH (6:3:1) as eluent and further purified on a C18 reverse-phase column. Two pure compounds were isolated, and these have been chemically characterized and given the trivial names fumonisin B1 and B2. At least 2 g of the major compound fumonisin B1 was purified from 1 kg of culture material. Fumonisin B1 in the diet (0.1%) significantly (P less than 0.001) induced the formation of GGT+ foci in the livers of initiated as well as noninitiated rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood chemical and electrolyte concentrations in the ostrich Struthio camelus

Serum levels of sodium, potassium, chloride, phosphorus, iron, total magnesium, total calcium, alkaline phosphatase, alanine transaminase, lactate dehydrogenase, creatine kinase, gamma-glutamyltransferase, aspartate transaminase, urea, creatinine, total protein, albumin and plasma glucose were determined in 49 ostriches (Struthio camelus) kept under semi-extensive conditions.

Induction of diplodiosis, a neuromycotoxicosis, in domestic ruminants with cultures of indigenous and exotic isolates of Diplodia maydis

Diplodiosis, a neuromycotoxicosis, principally of cattle, which is characterized by ataxia, paresis and paralysis, was induced in 13 cattle, 16 sheep and 3 goats, by dosing them with Diplodia maydis [= D. zeae (Schw.) Lév.] cultured on sterilized maize seeds. The results of these experiments confirmed the findings of earlier workers that diplodiosis is a mycotoxicosis caused by D. maydis. The intoxication was induced with cultures of South African isolates of D. maydis obtained from local maize, one of which was associated with a suspected field outbreak, and with cultures of isolates from maize imported from the United States of America and Argentina. Other findings emerging from the experiments were, inter alia, that cultures incubated for less than 8 weeks were seemingly non-toxic, that there was little individual variation in response of cattle to cultures of the different toxic isolates or batches of the isolates, that apparent relapses of clinical signs can occur several weeks after dosing had ceased and that a small percentage of animals can show permanent locomotory disturbance. Light microscopical examination revealed no lesions in acutely affected animals, but an extensive laminar subcortical status spongiosis was evident in the cerebrum and cerebellum of a sheep that had been long paralysed and a steer that had permanent locomotory disturbance.

Toxicity of Diplodia maydis in farm and laboratory animals

The acute toxicity of maize culture material of eight strains of Diplodia maydis in ducklings, as well as the ability of five of these strains to induce typical diplodiosis (a neuromuscular disease) in cattle and sheep was shown. Typical diplodiosis was induced in 17 sheep and 11 cattle. Two of the five toxic strains were isolated from maize involved in diploidiosis outbreaks, the others from commercial maize. Strains inducing diplodiosis could be isolated from commercial maize from the USA, Argentina and South Africa. There was no correlation between the toxicity of D. maydis strains in ducklings and their ability to induce diplodiosis in cattle and sheep. Some isolates were acutely toxic to ducklings and rats but were unable to induce diplodiosis in either cattle or sheep. Others, equally toxic to ducklings and rats, induced diplodiosis in cattle and sheep at low dose levels. Two doses, each of 5 g/kg, of maize culture material of isolates from the USA, Argentina and South Africa induced diplodiosis in sheep. Culture material incubated for less than 8 wk could not induce diplodiosis in cattle. Acute toxicity in ducklings and rats also increased with longer incubation periods. Cultures of non-sporulating and profusely sporulating strains were equally toxic to ducklings. Heat treatment of culture material for 48 days at 45 degrees C failed to reduce toxicity in ducklings.

Primary liver cancer and oesophageal basal cell hyperplasia in rats caused by Fusarium moniliforme

Fusarium moniliforme Sheldon is one of the most prevalent fungi associated with maize throughout the world. A correlation has been found between the incidence of F. moniliforme in home-grown maize and the human oesophageal cancer rate in Transkei, southern Africa. Culture material on maize of F. moniliforme strain MRC 826, isolated from maize in a high-risk area for oesophageal cancer in Transkei, was either freeze-dried or oven-dried and fed to groups of 20 inbred male BD IX rats on a life-long basis. At a dietary level of 8%, both types of culture material were hepatotoxic and caused 100% mortality. Hepatic lesions in rats that died were characterized by cirrhosis, nodular hyperplasia and bile-duct proliferation. At a dietary level of 4% for 286 days followed by 2% for the remainder of the experiment, both types of culture material were hepatocarcinogenic and caused hepatocellular carcinoma in 80% and ductular carcinoma of the liver in 63% of the rats surviving more than 450 days. Only one of 30 such rats did not have a primary hepatic carcinoma. No hepatocellular or ductular carcinomas occurred in the controls. Hepatocellular carcinomas in the experimental rats invariably developed in severely cirrhotic livers showing nodular hyperplasia. Adenofibrosis also developed concurrently with hepatocellular carcinoma. A higher incidence of basal cell hyperplasia occurred in the oesophageal epithelia of rats fed freeze-dried than in those fed oven-dried material. The chemical nature of the hepatotoxic and hepatocarcinogenic mycotoxin(s) produced by F. moniliforme is unknown.

Effect of trans-unsaturated fats on experimental atherosclerosis in vervet monkeys

Vervet monkeys ( Ceropithecus aethiops pygerethrus ) were placed on semipurified diets containing 14% fat of which 3.2 or 6.0% was present as trans-unsaturated fatty acid (t-FA). Two groups were fed the high and low levels of t-FA for a year and two others were fed t-FA for 6 months and then returned to the control diet for 6 months more. One other group was fed the control diet for a year. The control diet contained 14% fat which was a mixture of 72% olive oil and 28% corn oil. There were no significant differences in weight gain. Monkeys fed 6% t-FA or control diets for one year had lowest liver weights. Serum cholesterol and triglycerides in monkeys fed 3.2% t-FA for one year were 134 and 55 mg/dl, respectively; in monkeys returned to control diet after 6 months on 6% t-FA the values were 146 and 50 g/dl. Serum and triglyceride levels for the other 3 groups were 166 +/- 2 and 70 +/- 2 mg/dl. Liver cholesterol levels ranged from 4.0 mg/g (3.2% t-FA) to 4.7 mg/g (control) and 4.8 mg/g (6% t-FA). Lecithin:cholesterol acyltransferase (LCAT) activity was 59.0 microM/h for controls and ranged from 52.4 microM/h (3.2% t-FA) to 73.4 microM/h (6% t-FA). Cholesterol synthesis by liver slices was not affected by diet when the substrate was acetate. When mevalonate was used, the monkeys fed either level of t-FA for 12 months exhibited greatly reduced (about 80%) cholesterogenesis. The levels of t-FA in serum and liver reflected the amount in the diet. After being returned to control diet levels of t-FA in serum and liver of monkeys (fed 3.2% t-FA) fell by 97 and 94%, respectively, and those in serum and liver of monkeys fed 6% t-FA fell by 65 and 91%. There were no significant differences in aortic atherosclerosis or arteriosclerosis.(ABSTRACT TRUNCATED AT 400 WORDS)

Dietary wheaten bran in baboons: long-term effect on the morphology of the digestive tract and aorta, and on tissue mineral concentrations

Two groups of 13 young baboons, each consisting of 8 males and 8 females, were fed on either high- or low-bran diets (based on wheat of either high or low extraction rate) for a period of 26 months. All animals grew well and remained in good condition throughout. Male (but not female) baboons on the high-bran diet had lower (p less than 0.05) concentrations of zinc in serum and bone, despite a low phytate: zinc molar ratio and a high intake of zinc. Particle-induced X-ray emission analysis showed there to be lower concentrations of calcium, copper, zinc, sulphur, potassium and nickel in the livers of baboons on the high-bran diet (P less than 0.005). Baboons on the low-bran diet passed smaller quantities of softer faeces, they had fewer nodules of lymphoid tissue in the distal portion of the colon (P less than 0.05), and within mucosal microherniations of their ileo-caecal valves the epithelial cells showed a greater tendency to squamous transformation (P less than 0.05). Mucosal microherniations of the ileo-caecal valves tended to be more frequent and larger in size (P less than 0.05) in animals of the low-bran group. Morphometrical studies did not reveal any differences in the general structural development of the digestive tract. The high-bran diet had no effect on serum cholesterol concentrations, nor on the incidence or severity of atherosclerotic lesions of the aorta.

Influence of native and randomized peanut oil on lipid metabolism and aortic sudanophilia in the vervet monkey

Vervet monkeys (Cercopithecus aethiops pygerethrus) were fed cholesterol-free, semipurified diets containing 40% sucrose, 25% casein, 15% cellulose and 14% peanut oil (PNO), randomized peanut oil (RPNO) or corn oil (CO). After 4 months, serum cholesterol and triglyceride levels, serum lecithin-cholesterol acyl transferase (LCAT) activity and plasma lipoprotein lipase (LPL) activity were similar in all groups. Livers of monkeys fed CO converted 156% more acetate and 24% more mevalonate to cholesterol than those of monkeys fed RPNO. Cholesterogenesis in RPNO-fed monkeys was enhanced compared to PNO (68% from acetate; 62% from mevalonate). Incidence of atherosclerosis was 33% in monkeys fed RPNO, 80% in those fed CO and 90% in those fed PNO. Extent of sudanophilia was lowest in aortas of monkeys fed RPNO. Incidence of arteriosclerosis was 40% in monkeys fed CO, 56% in those fed RPNO and 70% in those fed PNO. Extent of aortic surface showing arteriosclerosis was highest in monkeys fed RPNO.

A comparative study of the toxicity of Fusarium verticillioides (= F. moniliforme) to horses, primates, pigs, sheep and rats

An isolate of Fusarium verticillioides (MRC826) that induced experimental leukoencephalomalacia, also caused acute toxicity when fed to pigs and administered per rumen fistula to sheep. Pigs developed severe pulmonary oedema while sheep manifested severe nephrosis and hepatosis. A less toxic isolate (F. verticillioides MRC602), fed to baboons, resulted in acute congestive heart failure or hepatic cirrhosis, depending on the dose. Both isolates were toxic to rats and caused similar lesions, namely, hepatic cirrhosis and intraventricular cardiac thrombosis.

A field outbreak of suspected stachybotryotoxicosis in sheep

An outbreak of mortality in a flock of mutton merino sheep in which 109 out of 568 sheep died in the south-western Cape Province, is described. It was characterized by haemorrhagic septicaemia, anaemia, leucocytopaenia and haemorrhagic tendencies. Mortalities followed unseasonal and heavy summer rain, extended over a period of 6 months and were associated with the uninterrupted consumption of sheep cubes processed on the farm severly fungus-infested wheat, barley and rye straw for a period of at least one month. The main clinical signs occurred in two phases: an elevated body temperature, listlessness, epistaxis and intermittent haemorrhagic diarrhoea during the first phase of the outbreak, and a progressively worsening anaemia, leucocytopaenia and less severe haemorrhagic tendencies and a terminally elevated body temperature during the second phase. The predominant autopsy findings were purpuric haemorrhage on serosal and mucosal surfaces and in most of the organs, enterorrhagia and severe pulmonary congestion and oedema during the first stage; anaemia was the predominant sign during the second stage - widespread haemorrhage still occurred but was less extensive. Pasteurella haemolytica was isolated from most of the animals autopsied during the first stage. Histologically the most salient features were atrophy and necrosis of the lymphoid tissue, aplastic anaemia and a markedly impaired inflammatory response. Extensive post-natal lamb mortalities, probably due to an Escherichia coli infection precipitated by the toxicosis, occurred during the outbreak. Toxigenic strains of Stachybotrys chartarum were isolated from the wheat and barley straw. Diethyl ether extracts of the wheat straw, sheep cubes and S. chartarum culture material elicited positive skin tests in rats following intradermal injection and the presence of 12,13-epoxytrichothecenes in these extracts were confirmed by thin layer chromatography. In feeding trials sheep cubes and wheat straw caused the death of 4/4 one-day-old Pekin ducklings and weanling Wistar rats in six and nine days, respectively. This is the first description of an outbreak of disease in sheep associated with the ingestion of S. chartarum-infested food components in the Republic of South Africa.

Toxicity of Diplodia maydis to laboratory animals

Ten strains of Diplodia maydis isolated from commercial corn samples and grown on whole yellow corn at 25 degrees C for 6 weeks were toxic to ducklings and rats. The degree of toxicity depended on the incubation period and temperature. Minimum incubation periods of 3 to 4 weeks and 6 weeks were necessary to cause mortality in ducklings and rats, respectively. Cultures incubated at 31 and 25 degrees C were much more toxic than those kept at 16 and 20 degrees C. Heat treatments at 80 to 90 degrees C destroyed most of the toxicity of moldy meal. Mild lesions of a similar histopathological nature were found in subclinically and lethally poisoned rats. These included toxic myocarditis, enteritis, focal renal tubular necrosis, degeneration and peripheral necrosis of the islets of Langerhans, and a generalized venous congestion.