Mycotoxic peripheral myelinopathy, myopathy, and hepatitis caused by Diplodia maydis in vervet monkeys

Pest categorisation of Stenocarpella maydis

The EFSA Plant Health Panel performed a pest categorisation of Stenocarpella maydis, a clearly defined fungus causing seedling blight, stalk and ear rot in maize, its only confirmed main host. The pathogen occurs in many countries of North, Central and South America, Africa, Asia and Oceania where maize is grown commercially. It is present in the EU with restricted distribution (Czech Republic and Spain). Stenocarpella maydis is not included in Commission Implementing Regulation (EU) 2019/2072. Plants for planting (maize seeds) is the main pathway of entry and spread in the EU. Host availability and climate are favourable for the establishment of the pathogen in maize-growing areas of the EU. The pathogen has a direct impact on yield and quality of maize production. Phytosanitary measures are available to mitigate further introduction and spread of the pathogen into the EU. The Panel concludes that S. maydis satisfies all the criteria to be regarded as a potential Union quarantine pest.

Failure of diplodiatoxin to induce diplodiosis in juvenile goats

Diplodiosis is an important neuromycotoxicosis of ruminants in South Africa when grazing on harvested maize fields in winter. It is believed to be caused by mycotoxin(s) synthesised by Stenocarpella (Diplodia) maydis. Although several metabolites have been isolated from S. maydis culture material, none of these have been administered to ruminants to reproduce the disease. The objectives of this study were to isolate diplodiatoxin and to administer it to juvenile goats. Diplodiatoxin, considered as a major metabolite, was purified from S. maydis-infected maize cultures (Coligny 2007 isolate). Following intravenous administration of 2 mg and 4 mg diplodiatoxin/kg body weight for five consecutive days to two juvenile goats, no clinical signs reminiscent of diplodiosis were observed. Based on previous experimental results and if diplodiatoxin was the causative compound, the dosage regimen employed was seemingly appropriate to induce diplodiosis. In addition, intraruminal administration of 2 mg/kg diplodiatoxin to one goat for three consecutive days also did not induce clinical signs. It appears as if diplodiatoxin alone is not the causative compound. Other metabolites and/or mixtures of diplodiatoxin and other mycotoxins, when available in sufficient quantities, should also be evaluated.

Diplodiatoxin, chaetoglobosins, and diplonine associated with a field outbreak of Stenocarpella ear rot in Illinois

Stenocarpella maydis causes a fungal dry-rot of maize ears and is associated with diplodiosis, a neuromycotoxicosis in cattle grazing harvested maize fields in southern Africa and Argentina. There have been no reports of Stenocarpella metabolites in maize crop residues. Chemical investigations of S. maydis-infected grain from ears exhibiting different levels of ear rot severity following a 2010 field outbreak of Stenocarpella ear rot in Illinois led to the detection of diplodiatoxin and chaetoglobosins M and O as major components in the ethyl acetate extracts by LC-MS. Following post-harvest moist incubation of the S. maydis-infected grain, the amounts of each compound increased (approx. tenfold) and chaetoglobosin K was detected as a dominant toxin. In separate (1)H NMR-based analyses, the neurotoxin diplonine was detected as a minor component in methanol extracts of S. maydis-infected grain as well as cultures of S. maydis isolates from Midwest corn. Proline betaine (=stachydrine) and glycine betaine were also detected in these extracts as major components. This constitutes the first report of chaetoglobosin M, chaetoglobosin O, proline betaine, or glycine betaine from S. maydis, and the first record of diplodiatoxin, diplonine, proline betaine, glycine betaine, or chaetoglobosins M, O, or K being associated with a natural field outreak of S. maydis ear rot.

Bioactive metabolites from Stenocarpella maydis, a stalk and ear rot pathogen of maize

Stenocarpella maydis is a fungal pathogen of major importance that causes a dry-rot of maize ears and is associated with a neuromycotoxicosis in cattle grazing harvested maize fields in southern Africa and Argentina. In an effort to investigate the potential roles of S. maydis metabolites in the fungal disease cycle, ethyl acetate extracts of solid-substrate fermentations of several S. maydis isolates from maize grown in the United States were found to exhibit significant phytotoxic, antifungal, and antiinsectan activity. Chemical investigations of extracts of S. maydis isolates from Illinois and Nebraska led to the isolation or detection of the known metabolites diplodiatoxin, chaetoglobosins K and L, and (all-E)-trideca-4,6,10,12-tetraene-2,8-diol as major components. A culture of Stenocarpella macrospora from maize grown in Zambia produced diplosporin and chaetoglobosins K and L as major components that were isolated. Diplodiatoxin produced significant lesions in a maize leaf puncture wound assay. Diplosporin and chaetoglobosin K displayed moderate antiinsectan activity in dietary assays against the fall armyworm Spodoptera frugiperda, while chaetoglobosin K exhibited significant antifungal activity against Aspergillus flavus and Fusarium verticillioides. Using LC-ESIMS and (1)H NMR data, diplodiatoxin was detected as a major component in S. maydis-rotted grain, stalks, and stalk residues. This constitutes the first report of chaetoglobosins K and L from S. maydis, of (all-E)-trideca-4,6,10,12-tetraene-2,8-diol from Stenocarpella, and the first reported detection of diplodiatoxin, or any other Stenocarpella metabolite, in diseased maize seeds and stalk tissues.

Biochemical Changes Induced in Liver and Serum of Diplodiatoxin (Stenocarpellamaydis) Treated Male and Female Rats

Present study was conducted to investigate the acute and sub-acute toxic effect of diplodiatoxin with special reference to biochemical membrane bound enzymes like aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT) and RBC acetylcholinesterase (AChE) in male and female rats. For acute study, rats were treated with a single oral dose of 5.7 mg/kg of diplodiatoxin, whereas for sub-acute study, the rats received 0.27 mg/kg/day for 21 days. Acute and sub-acute diplodiatoxin treatment caused loss in body weight and feed intake along with symptoms including irritation, dullness, tremors and convulsions. Diplodiatoxin caused a significant increase in serum ASAT and ALAT and a decrease in activity in the liver in both acute and sub-acute studies. This compound also significantly inhibited RBC AChE. Sexual dimorphism was observed when male rats were compared with female rats (p < 0.05). The enzyme alterations observed in the affected enzymes recovered to the normal levels by day 7 post treatment (withdrawal study) in both acute and sub-acute treated rats. A negative correlation was observed with regard to these enzymes when serum was compared with liver. These enzyme profiles show increases in serum with parallel decrease in liver, indicating necrosis of liver. These results suggest that diplodiatoxin has potential to affect hepatic end-points.

Effect of diplodiatoxin (Stenocarpella maydis) on some enzymatic profiles in male and female rats

Acute and subacute effects of diplodiatoxin were monitored with special reference to biochemical target enzymes like acid phosphatase (AcP), alkaline phosphatase (AkP), and acetylcholinesterase (AChE) in male and female rats. For acute toxicity study the rats were treated with single oral dose of 5.7 mg/kg of diplodiatoxin, whereas for subacute toxicity study the rats were orally treated with 0.27 mg/kg/day for 21 days. Diplodiatoxin caused loss in body weight and feed intake with other clinical symptoms. Due to the acute and subacute treatment of diplodiatoxin significant decreases were observed in serum AcP and AkP and also in liver AkP, whereas liver AcP increased in both male and female treated rats. Further, significant inhibition of brain AChE was observed in acute and subacute treated animals, indicating its effect on nerve synapsis. Sexual dimorphism was recorded when the activity of male rats was compared with female rats. The values were near those of controls on Day 7 (posttreatment), indicating recovery in the altered enzymes once the treatment was ceased. These results suggest that diplodiatoxin is toxic and has potential to affect the normal functioning of individuals and can cause changes in vital tissues such as liver.

Mycotoxins, general view, chemistry and structure

Mycotoxins induce diverse and powerful biological effects in test systems; some are carcinogenic, mutagenic, teratogenic, estrogenic, hemorrhagic, immunotoxic, nephrotoxic, hepatotoxic, dermotoxic, and neurotoxic. Mycotoxins have been unambiguously linked to the etiology of several diseases in animals. The discovery of aflatoxins in the early 1960s led to the resurgence of interest in human mycotoxicoses; mycotoxins are now recognized as causal factors of primary liver cancer, ergotism and alimentary toxic aleukia. The fumonisins and ochratoxins are suspected of playing a role in the etiology of esophageal cancer and Balkan endemic nephrotoxicity, respectively.

Pleural Mesocestoides and cardiac shock in an obese vervet monkey (Cercopithecus aethiops)

Only one case of infection by tetrathyridia larvae of the tapeworm genus Mesocestoides was detected in 416 necropsies of captive vervet monkeys (Cercopithecus aethiops). Two hundred nine larvae were distributed between both pleural cavities. Mass and size ranges of larvae were determined. A plasma cell reaction indicated a humoral immune response to parasite antigens, which may have contributed to acute, lethal cardiac shock. Coagulative myocytolysis was confirmed. The history of this case and associated circumstantial evidence and reports in the literature suggest that infection of primates by tetrathyridia probably occurs after capture rather than before.