Lathyrism a disease caused by the consumption of seeds of certain species of Lathyrus, mainly L. sativus (chick pea or chickling vetch), L. cicera (flat-podded vetch) and L. clymenum (Spanish vetchling). Large population of Bangladesh, India, and Algeria and less commonly in France, Italy, Spain, Australia and some other countries habitually eats these seeds. This disease is prevalent among horse and cattle as well as in man.

In an ancient Hindu treatise, Bhavaprakasa, it has been mentioned that 'the triputa pulse causes a man to become lame and it cripples and irritate nerves'. Hippocrates (c 400 BC) was also aware that certain peas were toxic to human beings. In the seventeenth century a ban was imposed on the consumption of chickling vetch in Wuttenberg. In 1873, Cantani in Italy named the disease as Lathyrism. A survey conducted as early as 1833 in India reported patients suffering from neurolathyrism in the villages where this crippling disease affects poor section of the people especially under conditions of famine when L. sativus, locally called khesari, forms the main part of the diet and several workers have since recorded such cases from time to time. Occasional use of the pulse, however, appears to be harmless.

Several epidemics were reported in the past in Bangladesh, especially in the west and northwest part of the country where khesari is produced in large quantities and is consumed as a major food item. Specially the agricultural labourers take rutee or chapatee made of khesari at lunch. Animals are equally susceptible to this disease. In human, the disease generally appears whenever a diet consisting of one third to one half of L. sativus seed is consumed for 3-6 months. The onset of the neurolathyrism is often sudden and it usually occurs during monsoon. In the early stage the patient finds difficulty in walking; the gait becomes jerky and the legs may have to cross while walking. Thigh and calf muscle become rigid and lower limbs are paralysed and death occurs in extreme cases.

Lathyrism is more prevalent in young males. In case of horse and cattle the limbs and the muscle of larynx are paralyzed and the animal suffers suffocation. In human, the lesions on the spinal cord indicate permanent destruction of tracts. In animal the disease is transient suggesting ischaemia and interference with function rather than permanent destruction of affected cord. No effective remedy has been found for lathyrism. Prostigmin gave only slight relief from pain in earlier stage. Putting the patient on a nutritive diet and stopping the intake of khesari check the disease. Boiling in water or by repeated steeping in hot water and discarding the extracts can detoxify the seeds. Roasting the seeds at 140'C for 15-20 minutes results in 80-90% destruction of the neurotoxins. [M Kabirullah]

See also grass pea.