Trichothecene toxicity on human megakaryocyte progenitors (CFU-MK)

Individual cytotoxicity of three major type A trichothecene, T-2, HT-2, and diacetoxyscirpenol in human Jurkat T cells

Mycotoxins are toxic, fungal secondary metabolites that contaminate agricultural commodities, food, and feed. Among them, T-2, HT-2, and diacetoxyscirpenol (DAS; the major type A trichothecene) are primarily produced from Fusarium species. These mycotoxins exert numerous toxicological effects in animals and humans, such as dermatotoxicity, haematotoxicity, hepatotoxicity, nephrotoxicity, neurotoxicity, and immunotoxicity. In the present study, human Jurkat T cells were used as a model to investigate apoptotic cell death induced by T-2, HT-2, and DAS. The results showed that T-2, HT-2, and DAS decreased cell viability and increased production of Reactive Oxygen Species in a time- and dose-dependency. Based on their IC50 values, they could be ranked in decreasing order of cytotoxicity as T-2 > HT-2 > DAS. All tested mycotoxins caused DNA fragmentation, up-regulated cytochrome C, caspase 3, and caspase 9 mRNA levels, and down-regulated the relative expression of Bcl-2 and caspase 8. The effects of these trichothecenes on apoptosis were determined based on flow cytometry. At the IC50 concentrations, the percentages of apoptotic cells were significantly higher than for the controls. Taken together, these data suggested that T-2, HT-2, and DAS could induce apoptosis through the mitochondrial apoptotic pathway.

Clinical and clinicopathological features and outcomes of cats with suspected dietary induced pancytopenia

BACKGROUND

After a strong epidemiological link to diet was established in an outbreak of pancytopenia in cats in spring 2021 in the United Kingdom, 3 dry diets were recalled. Concentrations of the hemato- and myelotoxic mycotoxins T-2, HT-2 and diacetoxyscirpenol (DAS) greater than the European Commission guidance for dry cat foods were detected in the recalled diets.

OBJECTIVES

To describe clinical and clinicopathological findings in cats diagnosed with suspected diet induced pancytopenia.

ANIMALS

Fifty cats presenting with pancytopenia after exposure to a recalled diet.

METHODS

Multicenter retrospective case series study. Cats with known exposure to 1 of the recalled diets were included if presented with bi- or pancytopenia and underwent bone marrow examination.

RESULTS

Case fatality rate was 78%. Bone marrow aspirates and biopsy examination results were available in 23 cats; 19 cats had a bone marrow aspirate, and 8 cats had a biopsy core, available for examination. Bone marrow hypo to aplasia-often affecting all cell lines-was the main feature in all 31 available core specimens. A disproportionately pronounced effect on myeloid and megakaryocytic cells was observed in 19 cats. Myelofibrosis or bone marrow necrosis was not a feature.

CONCLUSION AND CLINICAL IMPORTANCE

Mycotoxin induced pancytopenia should be considered as differential diagnosis in otherwise healthy cats presenting with bi- or pancytopenia and bone marrow hypo- to aplasia.

Toxicity and preventive approaches of Fusarium derived mycotoxins using lactic acid bacteria: state of the art

Mycotoxin contamination of food and feed is a serious food safety issue and causes acute and chronic diseases in humans and livestock. Climatic and agronomic changes helps in the proliferation of fungal growth and mycotoxin production in food commodities. Mycotoxin contamination has attracted global attention due to its wide range of toxicity to humans and animals. However, physical and chemical management approaches in practice are unsafe for well-being due to their health-hazardous nature. Various antibiotics and preservatives are in use to reduce the microbial load and improve the shelf life of food products. In addition, the use of antibiotic growth promotors in livestock production may increase the risk of antimicrobial resistance, which is a global health concern. Due to their many uses, probiotics are helpful microbes that have a significant impact on food and nutrition. Furthermore, the probiotic potential of lactic acid bacteria (LAB) is employed in various food and feed preparations to neutralize mycotoxins, antimicrobial activities, balance the gut microbiome, and various immunomodulatory activities in both humans and livestock. In addition, LAB produces various antimicrobials, flavouring agents, peptides, and proteins linked to various food and health care applications. The LAB-based processes for mycotoxin management are more effective, eco-friendly, and low-cost than physical and chemical approaches. The toxicity, novel preventive measures, binding nature, and molecular mechanisms of mycotoxins' detoxification using LAB have been highlighted in this review.

Deoxynivalenol: An Overview on Occurrence, Chemistry, Biosynthesis, Health Effects and Its Detection, Management, and Control Strategies in Food and Feed

Mycotoxins are fungi-produced secondary metabolites that can contaminate many foods eaten by humans and animals. Deoxynivalenol (DON), which is formed by Fusarium, is one of the most common occurring predominantly in cereal grains and thus poses a significant health risk. When DON is ingested, it can cause both acute and chronic toxicity. Acute signs include abdominal pain, anorexia, diarrhea, increased salivation, vomiting, and malaise. The most common effects of chronic DON exposure include changes in dietary efficacy, weight loss, and anorexia. This review provides a succinct overview of various sources, biosynthetic mechanisms, and genes governing DON production, along with its consequences on human and animal health. It also covers the effect of environmental factors on its production with potential detection, management, and control strategies.

Risk to human and animal health related to the presence of 4,15-diacetoxyscirpenol in food and feed

4,15‐Diacetoxyscirpenol (DAS) is a mycotoxin primarily produced by Fusarium fungi and occurring predominantly in cereal grains. As requested by the European Commission, the EFSA Panel on Contaminants in the Food Chain (CONTAM) assessed the risk of DAS to human and animal health related to its presence in food and feed. Very limited information was available on toxicity and on toxicokinetics in experimental and farm animals. Due to the limitations in the available data set, human acute and chronic health‐based guidance values (HBGV) were established based on data obtained in clinical trials of DAS as an anticancer agent (anguidine) after intravenous administration to cancer patients. The CONTAM Panel considered these data as informative for the hazard characterisation of DAS after oral exposure. The main adverse effects after acute and repeated exposure were emesis, with a no‐observed‐adverse‐effect level (NOAEL) of 32 μg DAS/kg body weight (bw), and haematotoxicity, with a NOAEL of 65 μg DAS/kg bw, respectively. An acute reference dose (ARfD) of 3.2 μg DAS/kg bw and a tolerable daily intake (TDI) of 0.65 μg DAS/kg bw were established. Based on over 15,000 occurrence data, the highest acute and chronic dietary exposures were estimated to be 0.8 and 0.49 μg DAS/kg bw per day, respectively, and were not of health concern for humans. The limited information for poultry, pigs and dogs indicated a low risk for these animals at the estimated DAS exposure levels under current feeding practices, with the possible exception of fattening chicken. Assuming similar or lower sensitivity than for poultry, the risk was considered overall low for other farm and companion animal species for which no toxicity data were available. In consideration of the similarities of several trichothecenes and the likelihood of co‐exposure via food and feed, it could be appropriate to perform a cumulative risk assessment for this group of substances.

Antibody response of growing German Holstein bulls to a vaccination against bovine viral diarrhea virus (BVDV) is influenced by Fusarium toxin exposure in a non-linear fashion

The Fusarium toxin deoxynivalenol (DON) is a frequent contaminant of feedstuffs and is supposed to interfere with immune responses. As the relevance for growing bulls is less clear than for other livestock, the trial was designed according to the dose-response principal with a control group fed a diet with background contamination (CON, 0.36 mg DON per kilogram dry matter [DM]) and three groups with increasing concentrations of DON (mg/kg DM); FUS I, 3.01; FUS II, 5.66; FUS III, 8.31. Half of each treatment group was vaccinated against BVDV at days 1 and 21 of the 70 days lasting experiment. Sequential blood samples were collected for determination of antibody titers to BVDV and for hematological and clinical-chemical traits. Antibody response was strongest in group FUS II while group FUS III responded weakest. This group showed the lowest proportion of CD4+ T cells, but also the highest levels of liver lesion indicating enzyme activities in blood. BVDV-vaccination induced a pronounced decrease in red blood count indices, which occurred dose-dependently at a higher level in the FUS-fed groups. The obvious interactions between DON exposure and BVDV-vaccination require further elucidation.

Risks to human and animal health related to the presence of deoxynivalenol and its acetylated and modified forms in food and feed

Deoxynivalenol (DON) is a mycotoxin primarily produced by Fusarium fungi, occurring predominantly in cereal grains. Following the request of the European Commission, the CONTAM Panel assessed the risk to animal and human health related to DON, 3-acetyl-DON (3-Ac-DON), 15-acetyl-DON (15-Ac-DON) and DON-3-glucoside in food and feed. A total of 27,537, 13,892, 7,270 and 2,266 analytical data for DON, 3-Ac-DON, 15-Ac-DON and DON-3-glucoside, respectively, in food, feed and unprocessed grains collected from 2007 to 2014 were used. For human exposure, grains and grain-based products were main sources, whereas in farm and companion animals, cereal grains, cereal by-products and forage maize contributed most. DON is rapidly absorbed, distributed, and excreted. Since 3-Ac-DON and 15-Ac-DON are largely deacetylated and DON-3-glucoside cleaved in the intestines the same toxic effects as DON can be expected. The TDI of 1 μg/kg bw per day, that was established for DON based on reduced body weight gain in mice, was therefore used as a group-TDI for the sum of DON, 3-Ac-DON, 15-Ac-DON and DON-3-glucoside. In order to assess acute human health risk, epidemiological data from mycotoxicoses were assessed and a group-ARfD of 8 μg/kg bw per eating occasion was calculated. Estimates of acute dietary exposures were below this dose and did not raise a health concern in humans. The estimated mean chronic dietary exposure was above the group-TDI in infants, toddlers and other children, and at high exposure also in adolescents and adults, indicating a potential health concern. Based on estimated mean dietary concentrations in ruminants, poultry, rabbits, dogs and cats, most farmed fish species and horses, adverse effects are not expected. At the high dietary concentrations, there is a potential risk for chronic adverse effects in pigs and fish and for acute adverse effects in cats and farmed mink.

Cytotoxicity and phytotoxicity of trichothecene mycotoxins produced by Fusarium spp

Trichothecenes, a major class of mycotoxins produced by Fusarium, Myrothecium, and Stachybotrys species, are toxic to both plants and mammals. Simple trichothecenes, including type A (e.g., T-2 toxin) and type B (e.g., deoxynivalenol), are generally less toxic than macrocyclic trichothecenes. We sought to determine if simple trichothecenes are a potential source of candidates for development as bioherbicides, which require high phytotoxicity and low mammalian toxicity. We examined 28 simple trichothecenes in vitro for phytotoxicity using a small aquatic plant, Lemna pausicostata, and for mammalian toxicity using four cultured mammalian cell lines. Several structure-activity relationships were identified, including the following two, which may be relevant to bioherbicide development: peracetylation of type B trichothecenes and de-epoxidation of type A trichothecenes both substantially reduced mammalian toxicity with little effect on phytotoxicity. It was concluded that simple trichothecenes possessing strong phytotoxicity and minimal mammalian toxicity in vitro can be identified.

Comparative hematoxicity of fusirium mycotoxin in experimental sprague-dawley rats

Mycotoxins are fungal toxin and contaminated to human through food-stuffs. Hematological abnormality, mainly thrombocytopenia and leukopenia are induced after consumption of mycotoxin. Experiments were conducted to evaluate the hematotoxicity of trichothecenes mycotoxins in Sprague-Dawley rats. Hematological parameters viz. Hemoglobin, hematocrit, erythrocyte count (RBC), white blood cell count (WBC), lymphocytes, monocytes, neutrophils, eosinophils, basophils, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, red blood cell distribution width, mean platelet volume, plateletcrit and platelet distribution width were determined at 0, 6, 12 and 24 h after injection of 0.5 ml of T-2, Deoxynivalenol (DON), nivalenol, zearalenone, neosolaniol, ochratoxin-B mycotoxin equivalent to 1 × 10(-3) μg/μl to Sprague-Dawley rats. Experiments showed that trichothecenes toxin produces severe hematological alternation. The reductions of RBC and WBC were observed in all Fusarium mycotoxins treated group. T-2 toxin group shows severe toxicity as compared to other mycotoxin treated group. DON is the least hematotoxicity and T-2 the most.

Co-exposure of Fusarium mycotoxins: in vitro myelotoxicity assessment on human hematopoietic progenitors

Mycotoxins such as beauvericin (BEA), deoxynivalenol (DON), enniatin B (ENB), fumonisin B1 (FB1), T-2 toxin and zearalenone (ZEA) can co-occur in food commodities. This aim of this study was to assess the myelotoxicity of these mycotoxins in couple using in vitro human granulo-monocytic (Colony Forming Unit-Granulocyte and Macrophage, CFU-GM) hematopoietic progenitors. Clonogenic assays have been performed in the presence of the following couples of fusariotoxins: DON + BEA, DON + FB1, DON + T-2, DON + ZEA, T-2 + ZEA and BEA + ENB. Co-exposure of human CFU-GM to DON + BEA resulted in synergic myelotoxic effects. The combination of DON + T-2 presented additive or synergic myelotoxic effects. The couples DON + ZEA, T-2 + ZEA and BEA + ENB had additive myelotoxic effects, while the combination of DON + FB1 showed antagonist myelotoxic effects. These in vitro results suggested that the simultaneous presence of mycotoxins in food commodities and diet may be more myelotoxic than the presence of one mycotoxin alone. Diminution of hematopoietic progenitors could give rise to a decrease number of mature blood cells, inducing agranulocytosis and/or thrombocytopenia and in severe cases aplastic anemia.

Toxicological mechanisms and potential health effects of deoxynivalenol and nivalenol

Produced by the mould genus Fusarium, the type B trichothecenes include deoxynivalenol (DON), nivalenol (NIV) and their acetylated precursors. These mycotoxins often contaminate cereal staples, posing a potential threat to public health that is still incompletely understood. Understanding the mechanistic basis by which these toxins cause toxicity in experimental animal models will improve our ability to predict the specific thresholds for adverse human effects as well as the persistence and reversibility of these effects. Acute exposure to DON and NIV causes emesis in susceptible species such as pigs in a manner similar to that observed for certain bacterial enterotoxins. Chronic exposure to these mycotoxins at low doses causes growth retardation and immunotoxicity whereas much higher doses can interfere with reproduction and development. Pathophysiological events that precede these toxicities include altered neuroendocrine responses, upregulation of proinflammatory gene expression, interference with growth hormone signalling and disruption of gastrointestinal tract permeability. The underlying molecular mechanisms involve deregulation of protein synthesis, aberrant intracellular cell signalling, gene transactivation, mRNA stabilisation and programmed cell death. A fusion of basic and translational research is now needed to validate or refine existing risk assessments and regulatory standards for DON and NIV. From the perspective of human health translation, biomarkers have been identified that potentially make it possible to conduct epidemiological studies relating DON consumption to potential adverse human health effects. Of particular interest will be linkages to growth retardation, gastrointestinal illness and chronic autoimmune diseases. Ultimately, such knowledge can facilitate more precise science-based risk assessment and management strategies that protect consumers without reducing availability of critical food sources.

T-2 toxin and HT-2 toxin in grain and grain-based commodities in Europe: occurrence, factors affecting occurrence, co-occurrence and toxicological effects

This paper presents an overview of the occurrence of T-2 toxin and HT-2 toxin in cereals in Europe and derived food products, factors influencing the occurrence, co-occurrence with other trichothecenes, and toxicological effects of T-2 and HT-2 in human. Of all cereals, oats showed to be most susceptible to T-2/HT-2 contamination. Particularly, oats grown in Scandinavia and UK in the period 2003-2007 were highly contaminated. This contamination has reduced in 2008 and 2009. In raw cereals, T-2 and HT-2 levels were highly correlated with each other in most instances, with the HT-2 level being two to seven times higher than the T-2 level. The toxin levels showed not to be correlated with levels of deoxynivalenol and nivalenol. The occurrence of T-2 and HT-2 in the field varied between years, regions, cereal grain varieties, sowing time, and precrop. Organically produced cereals contained lower T-2 and HT-2 levels as compared to conventionally grown cereals. Little or no effects from using fungicides was seen. Processing cereals resulted in low T-2 and HT-2 levels in food products, although oat products contained some T-2 and HT-2. The by-products from food processing, often used for animal feeding, frequently were highly contaminated. T-2 and HT-2 showed to have high acute and subacute toxicity, as they caused haematotoxic, immunotoxic, cytotoxic, and dermal effects. Carcinogenicity of T-2 and HT-2 in human has not been proven. Outbreaks of human toxicosis caused by trichothecenes, including T-2 and HT-2, have been reported. The present overview is deemed to be valuable for risk assessments at the European level, planned to be held by EFSA. It also provides directions for further research, including the ecology of the fungi responsible for T-2 and HT-2, and agronomical practices to reduce the contamination in the field.

Deoxynivalenol: mechanisms of action, human exposure, and toxicological relevance

The trichothecene mycotoxin deoxynivalenol (DON) is produced in wheat, barley and corn following infestation by the fungus Fusarium in the field and during storage. Colloquially known as "vomitoxin" because of its emetic effects in pigs, DON has been associated with human gastroenteritis. Since DON is commonly detected in cereal foods, there are significant questions regarding the risks of acute poisoning and chronic effects posed to persons ingesting this trichothecene. A further challenge is how to best manage perceived risks without rendering critical food staples unavailable to an ever-expanding world population. In experimental animal models, acute DON poisoning causes emesis, whereas chronic low-dose exposure elicits anorexia, growth retardation, immunotoxicity as well as impaired reproduction and development resulting from maternal toxicity. Pathophysiologic effects associated with DON include altered neuroendocrine signaling, proinflammatory gene induction, disruption of the growth hormone axis, and altered gut integrity. At the cellular level, DON induces ribotoxic stress thereby disrupting macromolecule synthesis, cell signaling, differentiation, proliferation, and death. There is a need to better understand the mechanistic linkages between these early dose-dependent molecular effects and relevant pathological sequelae. Epidemiological studies are needed to determine if relationships exist between consumption of high DON levels and incidence of both gastroenteritis and potential chronic diseases. From the perspective of human health translation, a particularly exciting development is the availability of biomarkers of exposure (e.g. DON glucuronide) and effect (e.g. IGF1) now make it possible to study the relationship between DON consumption and growth retardation in susceptible human populations such as children and vegetarians. Ultimately, a fusion of basic and translational research is needed to validate or refine existing risk assessments and regulatory standards for this common mycotoxin.

Determinación de tricotecenos, zearalenona y zearalenoles en alimentos derivados de maíz del mercado español

Among the main Spanish commercially available trademarks, we have selected a total of 25 samples of corn-based foods, which have the highest consume rate, to carry out the analysis of deoxynivalenol (DON), T-2 toxin, zearalenone (ZEA) and zearalenols (ZOL). The contents of mycotoxins were determined by gas chromatography with flame ionization detection, and those of ZEA were confirmed by HPLC with fluorescence detection. Of the 25 analyzed samples, the incidence of DON, ZEA and alfa-ZOL was 68, 44 and 24%, respectively; levels detected ranged from 29-195, 34-216, and 36-71 microg/kg, respectively. T-2 toxin was only detected in one sample (<50 microg/kg). Beta-ZOL was not present in excess of the detection limit in the investigated samples. The results suggest a risk for consumers of corn products and the need to monitor the final products before consumption. This is the first report in Spain on natural contamination with these mycotoxins in corn-based foods.

Toxic Alterations in Chick Embryonic Liver and Spleen by Acute Exposure to Fusarium-Producing Mycotoxin Deoxynivalenol

Food mycotoxin deoxynivalenol (vomitoxin, DON) produced by Fusarium graminearum and F. culmorum can induce rapid diminution of lymphoid tissues and lymphopenia in the growing chickens and mammals. We first investigated the direct acute effects of DON on the chick immune-related embryo tissues such as embryonic liver and spleen. Direct DON administration into the embryonic eggs caused toxin accumulation in liver in a time-dependent manner. Electron microscopic observation showed a notable accumulation of fat droplet in the liver tissue and the re-exposed hatched chicken showed more distinguishing enlarged fat globules, so-called fatty cysts like human steatosis. Regarding effects of deoxynivalenol on the chick embryonic spleen, fatty change was also observed in splenocytes. Functionally, mitogen-stimulated cellular and humoral lympho-proliferations were suppressed in the DON-treated embryo. Conclusively, acute direct exposure to deoxynivalenol in the chick embryo caused toxic histological alterations in the liver and spleen and suppressed in vitro lymphoblastogenesis.

In vitro effects of trichothecenes on human dendritic cells

The aim of this work was to study the in vitro effects of trichothecenes on human dendritic cells. Trichothecenes are mycotoxins produced by fungi such as Fusarium, Myrothecium, and Stachybotrys. Two aspects have been explored in this work: the cytotoxicity of trichothecenes on immature dendritic cells to determine IC 50 (inhibition concentration), and the effects of trichothecenes on dendritic cell maturation process. Two mycotoxins (T-2 and DON) known to be immunotoxic have been tested on a model of monocyte-derived dendritic cells culture. Cytotoxic effects of T-2 toxin and DON on immature dendritic cells showed that DON is less potent than T-2 toxin. The exposure to trichothecenes during dendritic cell maturation upon addition of LPS or TNF-alpha markedly inhibited the up-regulation of maturation markers such as CD-86, HLA-DR and CCR7. Features of LPS or TNF-alpha -mediated maturation of dendritic cells, such as IL-10 and IL-12 secretions and endocytosis, were also impaired in response to trichothecenes treatment. These results suggest trichothecenes have adverse effects on dendritic cells and dendritic cell maturation process.

Myelotoxicity of trichothecenes and apoptosis: An in vitro study on human cord blood CD34+ hematopoietic progenitor

Previous studies have revealed that hematological disorders associated with trichothecenes intoxication in humans could result from hematopoiesis inhibition. The most frequent and potent trichothecene mycotoxins are T-2 toxin and deoxynivalenol (DON), respectively. Apoptosis induction by these two toxins was investigated in vitro on human hematopoietic progenitors (CD34+ cells). Hoechst coloration, DNA fragmentation and annexin-V/PI labeling in flow cytometry showed that T-2 toxin, in contrast to DON, induced apoptosis in CD34+ cells. T-2 toxin effect was dose- and time-dependent with a significant increase of apoptotic cells as early as 3h after incubation at 10(-7) M and a maximum reached at 12 h. This observation evidenced the high sensitivity of hematopoietic progenitors to T-2 toxin. The inhibition of T-2 toxin-induced apoptosis by a pan-caspase inhibitor (Z-VAD-fmk) suggested the involvement of caspases. The proportional increase of caspase-3 specific activity (DEVDase) with T-2 toxin concentration confirmed its role in the process. After incubation of CD34+ cells with T-2 toxin, in conditions that induced apoptosis, clonal expansion of granulo-monocytes, erythrocytes and megakaryocytes precursors was dose-dependently inhibited. The hematological effects observed in T-2 toxin mycotoxicosis could then be assigned to hematopoiesis inhibition by apoptosis. Different mechanisms that need to be further elucidated are involved in DON myelotoxicity.

Threat assessment of mycotoxins as weapons: molecular mechanisms of acute toxicity

Mycotoxins are impractical as tactical weapons, butthey can be used by small poor terrorist organizations to poison food and water sources or can be released in crowded, confined areas. Crude concentrated or dried extracts of readily grown fungal cultures can be used as weapons. The production of fungal weapons does not require elaborate facilities for the growth of fungi, sophisticated equipment for the purification of the toxins, or highly trained personnel. Aflatoxin B1, fumonisin B1, ochratoxin A, and the trichothecenes T-2 toxin and deoxynivalenol could be weaponized for bioterrorism. Knowledge of the symptoms of intoxication and the biochemical mechanisms of action of mycotoxins is necessary for the rapid identification of the toxins, the development of prophylactic antidotes, and the design of effective treatments of affected persons. All of these mycotoxins except deoxynivalenol are carcinogens (Stark, A. A., Annu. Rev. Microbiol. 34:235-262, 1980; Stark, A. A., p. 435-445, in P. S. Steyn and R. Vleggaar, ed., Mycotoxins and phycotoxins, 1986; Stark, A. A., p. 47-60, in C. L. Wilson and S. Droby, ed., Microbial food contamination, 2000; Stark, A. A., and N. Paster, p. 60-64, in M. L. Wahlqvist, A. S. Truswell, R. Smith, and P. L. Nestel, ed., Nutrition in a sustainable environment, 1994). Because immediate and widespread death, illness, or panic is the goal of bioterrorists, the mechanisms by which mycotoxins exert acute toxicity are the focus of this article.

Haematotoxicity of trichothecenes

Human toxicosis induced by consumption of foodstuffs contaminated with trichothecenes presents one common major symptom: a haematological perturbation manifesting principally as thrombocytopenia and leukopenia. The patients have rapidly progressing coagulation problems, and compromised resistance to infections. Consequently, they are subject to septicaemia and massive haemorrhages. In horses, cattle, poultry, cats, mice and guinea pigs, subacute and subchronic ingestion of trichothecenes causes a decrease of circulating blood cells frequently associated with bone marrow failure. The origins of haematological effects observed in Fusarium toxin intoxications have been elucidated using in vitro tests. Haematopoietic progenitors are the main target of trichothecenes. Deoxynivalenol (DON) is the least myelotoxic and T-2 the most. As circulating blood cells present a less important sensitivity to these toxins, haematological troubles observed in toxicosis are due to myelotoxicity of these toxins.