Ricinus communis

Abstract

DISTRIBUTION: Commonly found along roadsides and watercourses and disturbed soil. It is planted in gardens and cultivated for medicinal purposes. A declared invader plant that has to be eradicated. Originally from tropical Africa.

BOTANICAL DESCRIPTION: General: A much-branched woody bush or small tree that grows up to 4 m high. Leaves: The large, shiny dark green or reddish leaves have serrated edges and look like a five- to nine-pointed star. Flowers: The flowers are creamy coloured at the lower ends and reddish at the top. August to April. Fruit: The spiky fruit can be green, brown or red, with one seed in each of its three compartments. The glossy seed is mottled in shades of brown and white.

TOXIC PRINCIPLE: • The toxic principle is ricin, a toxalbumin or plant lectin, Mm. 70 000 daltons, water soluble and poorly absorbed. • Not totally denatured by proteolytic enzyme action. • Enough absorbed from g.i.t. to be very toxic by oral route. • Completely denatured by thorough heat treatment. • Any ricin present in castor oil (a safe irritant purgative) is denatured by heating. Toxicity: • Ricin: One of the most toxic substances known • Castor oil seed: Horses most susceptible of farm animals, ruminants intermediate and poultry least • Oil cake: Can be detoxified by heat, but should only be used as an organicfertilizer. In South Africa often not sufficiently detoxified • Leaves: Eaten by stock without any effect.

SYNDROMES: Toxalbumin.

SYSTEMS AFFECTED: Gastro-intestinal system.

CLINICAL SIGNS: • Latent period a few hours to days. • High dose results in sudden collapse. • Usually severe gastrointestinal irritation and its consequences: - Severe purgation, - watery to haemorrhagic diarrhoea, - dehydration and - weakness as a consequence. • Anorexia, colic and tympany. • Immunosuppression.

NECROPSY: Macroscopical findings: • Haemorrhagic, necrotic gastro-enteritis • Lymph node necrosis • Haemorrhages in g.i.t. and lymph nodes.

HISTOPATHOLOGY: Karyorrhexis of lymphocytes in lymph nodes in addition to g.i.t. lesions.

TREATMENT: • Symptomatic and supportive. • Hyperimmune serum: Very effective, but economically impractical and therefore not available. (An aid to the diagnosis if available). • Remember immunity to toxalbumins may develop. • Castor oil cake should never be used as feed under any circumstances.