Laythrism for psm exam
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lathyrism PSM community medicine exam notes neurolathyrism khesari dal
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Here is a complete PSM exam note on Lathyrism (spelled correctly), sourced directly from Park's Textbook of Preventive and Social Medicine:
Lathyrism - PSM Exam Notes (Park's)
Definition
Lathyrism is a paralyzing disease of humans and animals caused by consumption of the pulse Lathyrus sativus.
- In humans - called Neurolathyrism (affects the nervous system)
- In animals - called Osteo-lathyrism / Odoratism (pathological changes in bones causing skeletal deformities)
The Pulse
| Feature | Detail |
|---|---|
| Scientific name | Lathyrus sativus |
| Common name | Khesari dhal |
| Local names | Teora dhal, Lak dhal, Batra, Gharas, Matra |
| Appearance | Triangular shape, grey colour; dehusked looks like red gram or bengal gram |
| Affected population | Poor agricultural labourers (cheap food) |
| Threshold | Diets with >30% lathyrus dhal over 2-6 months causes neurolathyrism |
The Toxin
- BOAA = Beta Oxalyl Amino Alanine (also written as ODAP / beta-N-oxalyl-amino-L-alanine)
- Water soluble (important for control measures)
- Blood-brain barrier exists, so large amounts must be eaten over 2+ months to overcome it
- It is a glutamate analogue - acts as excitotoxin on upper motor neurons
Epidemiology
- Prevalent in: Madhya Pradesh, UP, Bihar, Orissa (also Maharashtra, WB, Rajasthan, Assam, Gujarat)
- At peak: Rewa district MP had 25,000 cases; Satna district had 32,000 cases
- Also reported in Spain and Algeria
- Fresh outbreaks have declined due to changing agronomical practices
Clinical Stages of Neurolathyrism
The disease mainly affects young men aged 15-45 years and progresses in stages:
| Stage | Description |
|---|---|
| (a) Latent stage | Apparently healthy; abnormal gait on physical stress; neurological signs present. Complete remission possible if dhal withdrawn at this stage |
| (b) No-stick stage | Walks with short jerky steps WITHOUT a stick |
| (c) One-stick stage | Crossed gait, tends to walk on toes; uses ONE stick for balance |
| (d) Two-stick stage | More severe; excessive knee bending and crossed legs; needs TWO crutches |
| (e) Crawler stage | Cannot maintain erect posture; atrophy of lower limb muscles; crawls on all fours |
Key exam point: The condition is irreversible in advanced stages. Only the latent stage is reversible on withdrawal of the pulse.
Prevention and Control
(a) Vitamin C prophylaxis
- 500-1000 mg ascorbic acid daily for a week can repair some damage
- Generous Vitamin C in lathyrogenic diet prevents damage (shown in guinea pigs and monkeys)
(b) Banning the crop
- Prevention of Food Adulteration Act - has banned lathyrus in all forms (whole, split, flour) in India
- However, the ban is NOT operative in endemic states (MP, Bihar, Orissa, Gujarat)
- If consumption is unavoidable, lathyrus should be <25% (not more than a quarter) of total cereals and pulses per day
(c) Removal of toxin (Detoxification)
- (1) Steeping method: Soak in hot water for 2 hours, drain the soak water, wash with clean water, dry in sun. Drawback: loss of vitamins and minerals
- (2) Parboiling: Like parboiled rice; soaking in lime water overnight + boiling destroys the toxin AND trypsin inhibitors. Suitable for large-scale operation
(d) Education - Educate the public about dangers and need for detoxification
(e) Genetic approach
- Certain strains contain very low toxin levels (0.1%)
- Selective propagation of low-toxin strains - most effective long-term solution
- Low-toxin varieties available from Indian Agricultural Research Institute (IARI), New Delhi
(f) Socio-economic changes
- Ultimate solution is overall socio-economic development
Quick Recall Table (High-yield for MCQs)
| Point | Answer |
|---|---|
| Causative pulse | Lathyrus sativus (Khesari dhal) |
| Toxin | BOAA (Beta Oxalyl Amino Alanine) |
| Type of toxin | Water soluble, excitotoxin |
| Disease in humans | Neurolathyrism |
| Disease in animals | Osteo-lathyrism |
| Clinical feature | Spastic paraplegia of lower limbs |
| Age group affected | 15-45 years, mainly males |
| Reversible stage | Latent stage only |
| % dhal causing disease | >30% over 2-6 months |
| Legal ban | Prevention of Food Adulteration Act |
| Best control method | Genetic approach (low-toxin strains from IARI) |
| Detoxification at home | Steeping (hot water soaking) |
| Large-scale detox | Parboiling with lime water |
| Vitamin prophylaxis | Vitamin C 500-1000 mg/day |
Source: Park's Textbook of Preventive and Social Medicine, Chapter on Nutritional Diseases
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