Walter Friedrich Otto Marasas was born in Boksburg, South Africa on 25 October 1941. On October 30, 1965, he married Hendrika (Rika) Maria Nel in Madison, Wisconsin. Their daughter, Carissa Nalette Marasas, was born in Madison in 1966, and their son, Walter Friedrich Otto Marasas Jr., was born in Pretoria in 1972. Carissa (M.Sc. in plant pathology, Ph.D. in agricultural economics) works for the USDA-APHIS in Washington D.C., and Walter, a businessman, lives in Pretoria with his wife and three children. Wally and Rika live in Durbanville, near Cape Town, South Africa.
Professor Marasas became interested in the natural world at an early age and received a scholarship to study plant pathology. He obtained his B.Sc. in 1962 and M.Sc. in 1965, both from the University of Pretoria. Dr. Chris Rabie, Wally’s M.Sc. advisor and a graduate of the University of Wisconsin (UW), recognized Wally’s potential and encouraged him to go to his alma mater for his Ph.D. Wally’s time in Wisconsin played an important role in setting his career path in mycotoxicology. While at UW, Wally isolated Fusarium sporotrichioides from feed grain that had killed livestock in Wisconsin. In collaboration with Jim Bamburg, the trichothecene T-2 toxin was first isolated from this fungus. Wally determined that F. sporotrichioides produced sufficient quantities of the toxin in contaminated grain to cause death and the characteristic symptoms. Under the guidance of Professors E. B. Smalley and M. P. Backus, Wally received his Ph.D. in plant pathology in 1969.
Marasas returned to South Africa in 1969 as mycologist with the Plant Protection Research Institute of the Department of Agricultural Technical Services in Pretoria. He had diverse responsibilities at the institute, but was able to initiate new and important mycotoxicological research while there. His collaboration with Dr. Fanie Kellerman, a veterinarian at the Onderstepoort Veterinary Research Institute who also had a degree in plant pathology, was particularly rewarding. They investigated equine leukoencephalomalacia (ELEM), a disease that causes brain lesions in horses. Once again, moldy corn that was used as feed was a suspected cause. In short order, Dr. Marasas identified F. verticillioides (previously known as F. moniliforme) as the culprit, and showed that it alone could cause symptoms of ELEM. Thus began his decades-long examination of this fungus and its impact on animal and human health.
In 1975, Wally Marasas became a chief specialist scientist with the South African Medical Research Council (MRC) in Tygerberg near Cape Town. He has remained with MRC ever since, becoming the leader of the Programme on Mycotoxins and Experimental Carcinogenesis (PROMEC) in 1992, and director of PROMEC in 2001. His most outstanding and significant contributions have come during his tenure with MRC. With a multidisciplinary group of scientists, he has investigated the high incidences of esophageal cancer (EC) that occur in the Transkei region of the Eastern Cape Province in South Africa. Wally showed that home-grown corn, the staple food for local populations, was contaminated with the fungus that causes ELEM, F. verticillioides, and although he could not determine its effect on humans, he did demonstrate that it caused liver cancer in rats. After years of hard work, Wally’s team isolated a new group of mycotoxins, the fumonisins, from strains of F. verticillioides from the Transkei, determined their chemical structure, and developed analytical methods for their detection. In animals, fumonisin B1 caused the same symptoms that were induced by F. verticillioides-infested moldy maize and F. verticillioides by itself. Concentrations as low as 10 ppm caused ELEM and 50 ppm caused liver cancer in rats. Concentrations as high as 117 ppm were found in home-grown corn that was consumed by people in the Transkei and indicated that F. verticillioides-infested corn may play a role in the high rates of EC. Since their discovery, the fumonisins have been associated with another hotspot of EC in China, have been shown to induce a third animal disease, porcine pulmonary edema (PPE), and have been associated with serious outbreaks of ELEM and PPE in the United States. The International Agency for Research on Cancer now classifies fumonisins as Group 2B carcinogens, e.g., probably carcinogenic to humans. With Professor Marasas’s assistance, the World Health Organization is engaged in an intensive assessment of health risks posed by the consumption of these mycotoxins. Wally Marasas has been called the “world’s most well-known mycotoxicologist” and is recognized as one of the outstanding mycologists in South Africa. He has authored three books, 50 book chapters, and over 300 papers in refereed journals on a wide range of mycotoxicological, mycological, and plant pathological topics. His research is published in high-impact journals and is frequently referenced by colleagues; 13 of his publications have been cited over 100 times. He is an Institute of Scientific Information (ISI) “Highly Cited” author, and is in the top 10 for numbers of citations in two different ISI categories, agricultural sciences and plant and animal sciences.
Wally Marasas is a widely sought keynote and plenary speaker (to date, well over 150 have been given at international conferences), is an advisor and consultant with several global health and scientific organizations, and despite having no official academic appointment, is a frequent advisor of M.Sc. and promoter of Ph.D. students. He is a Fellow of the South African Society for Plant Pathology; has received several honorary memberships, professorships, and doctorates; and has received numerous prestigious awards, including the Christiaan Hendrik Persoon Gold Medal for Scientific Excellence and Outstanding Achievements in Plant Pathology, the Wellcome Gold Medal for Medical Research, the Silver Medal for Excellence in Research from the Medical Research Council, the African Academy of Sciences/ CIBA Prize for Agricultural Biosciences, and the MT Steyn Gold Medal for Scientific and Technical Achievement. Wally Marasas has been very effective in integrating the fields of plant pathology and mycotoxicology. He has had a major influence on the fields of mycotoxicology and mycology, as well as the areas of human and animal health. He is clearly a most deserving candidate for the award of APS Fellow.
