Last week, tragedy struck the Bandhavgarh Tiger Reserve, a national park nestled in the hills of central India. Four wild elephants lay dead as forest officials discovered six others from the same herd were unwell. Despite treatments, all six succumbed to their illness within two days.
Forest officials and researchers alike wondered what brought down these mighty animals. They immediately turned their attention to prime suspect number one: a fungus that infects kodo millets, a cereal grain that elephants feed on in this region.
This is not the first instance of animals or people falling ill after consuming kodo millets. Reports from the early 20th century described patients suffering from symptoms like vomiting, giddiness, unconsciousness, irregular pulse, shaking of limbs, and tremors. In human infection cases, flushing the stomach contents facilitated recovery, preventing any fatalities.1,2 However, animals like dogs and elephants succumbed to their symptoms after eating kodo millets.2
Another case of kodo poisoning in humans in 1985 led researchers to investigate the cause of illness. They found that the seeds were heavily infected by the fungi Aspergillus flavus and Aspergillus tamarii, which produced the toxin cyclopiazonic acid (CPA).3 Later research revealed that several species of the fungi Penicillium and Aspergillus also produce CPA.4
Back in Bandhavgarh Tiger Reserve, veterinarians suspect that these fungi are involved in the recent kodo millet poisoning that led to the deaths of 10 elephants. Postmortem toxicology analyses identified high levels of CPA in the stomachs of the deceased elephants.
“Aspergillus and Penicillium species form spores,” said Kaustuv Sanyal, a mycologist at Jawaharlal Nehru Center for Advanced Scientific Research. These microscopic particles can disperse through air and help the fungi survive and reproduce.5 “You need moist conditions for fungal spores to grow in, that’s why in jungles after rain, you have lots of fungal growth.”
People have often observed kodo millets “turning poisonous” after monsoon, and ingesting millets harvested after rainfall can result in adverse health conditions.6 According to some news outlets, the region around Bandhavgarh Tiger Reserve saw heavy rains and an unusually prolonged monsoon season.
Such humid conditions create a conducive environment for fungal spores to germinate and penetrate through the grain’s surface. While infecting plants, the fungi release enzymes that breakdown molecules in the host tissue to obtain energy, producing mycotoxins like CPA in the process.7
CPA's toxic properties are due to its ability to inhibit enzymes that transport calcium ions. This results in disruption of the calcium gradient that is crucial for maintaining cellular processes like proliferation, differentiation, and cell death, resulting in neuromuscular symptoms.8 In rodent experiments, researchers discovered that CPA can also cause toxicity in the liver by altering the levels of vital enzymes like glutamate pyruvate transaminase and glutamate oxaloacetate transaminase.9
Despite causing such adverse health effects in animals and humans, mycotoxins do not usually cause poisoning in the plant.10 “Their mechanism of plant toxicity is an interesting aspect which we have limited knowledge of,” said Amey Redkar, a researcher who studies plant-fungus interactions at the National Center for Biological Sciences.
Redkar further noted that toxicology reports identifying high levels of CPA provide hints about the likely fungal contamination in the diets of elephants. “But it is still uncertain,” he said, since researchers haven’t taken a look at samples from the plants at the national park. According to a news report, forest officials will send samples of the millet from the field where the elephant herd had grazed to experts for examination.
“We do have tools, and we do have markers wherein we could easily identify which genera of fungus [infected the millets],” he said. Assessing the millets can provide answers about the possibility of fungal infection that may have caused this wildlife tragedy, he added.
- Swarup A. Acute “Kodon” poisoning. Ind Med Gaz. 1922;57(7):257.
- Ayyar KV, Narayanaswamy K. Varagu poisoning. Nature. 1949;163, 912-913.
- Rao BL, Husain A. Presence of cyclopiazonic acid in kodo millet (Paspalum scrobiculatum) causing ‘kodua poisoning’ in man and its production by associated fungi. Mycopathologia. 1985;89(3):177-180.
- Burdock GA, Flamm WG. Review article: Safety assessment of the mycotoxin cyclopiazonic acid. Int J Toxicol. 2000;19(3):195-218.
- Ramírez AC, et al. Assessment of fungal spores and spore-like diversity in environmental samples by targeted lysis. BMC Microbiol. 2023;23(1):68.
- Bhide NK, Aimen RA. Pharmacology of a tranquillizing principle in Paspalum scrobiculatum grain. Nature. 1959;183(4677):1735-1736.
- Deepika C, et al. “Kodo poisoning”: Cause, science and management. J Food Sci Technol. 2021;59(7):2517-2526.
- Chang PK, et al. Cyclopiazonic acid biosynthesis of Aspergillus flavus and Aspergillus oryzae. Toxins. 2009;1(2):74-99.
- Antony M, et al. Potential risk of acute hepatotoxicity of kodo poisoning due to exposure to cyclopiazonic acid. J Ethnopharmacol. 2003;87(2-3):211-214.
- Awuchi CG, et al. Mycotoxins affecting animals, foods, humans, and plants: Types, occurrence, toxicities, action mechanisms, prevention, and detoxification strategies—A revisit. Foods. 2021;10(6):1279.
