Epidemic dropsy is an acute non-infectious disease resulting from use of edible oils adulterated with Argemone mexicana (mexican poppy) seed oils. It occurs as an epidemic (unusual occurrence of disease above what is normally expected in that population in that area) form in places where mustard oil is commonly used as cooking mediums as in North, North-Western and North- Eastern states of India, generally sparing South Indian states where the predominant cooking oil is coconut oil. In Western Rajasthan, India a small outbreak was reported from consumption of contaminated sesame seeds oil with Argemone Mexicana.
Epidemic dropsy was first reported by Lyon in 1877 from Calcutta, India and since then outbreaks/cases were reported from West Bengal, Bihar, Orissa, Madhya Pradesh, Uttar Pradesh, Gujarat, Haryana, Maharashtra, Delhi, Jammu and Kashmir, Assam, Rajasthan and Punjab.
The main symptom of epidemic dropsy consists of bilateral swelling of legs often associated with erythema, diarrhea, dyspnoea, glaucoma. Persons of all ages and both sexes were affected except breastfed infants and small children who have no mustard oil in their diets.
Epidemic dropsy has been also reported from Fiji Islands, Madagascar, Mauritius and Cape Districts of South Africa. All outbreaks were related to the intake of mustard oil contaminated with argemone oil except in the South African epidemic which occurred because of consumption of wheat flour adulterated with argemone seeds.
The disease is mostly reported in epidemic form but sporadic cases were also reported. Both sexes were involved equally. Persons of all ages were affected except breastfed infants and small children who have no mustard oil in their diets.
- Onset is usually insidious with watery diarrhoea and vomiting. This may last from a few days to more than a week.
- Intermittent or continuous fever, ranging from 99°F to 100.5°F, usually not high grade
- Joint pains, muscular pains, and low backache.
- Bilateral pitting oedema of the lower limbs extending from the ankles up to the scrotum and abdominal wall.
- Oedema increases after standing, typically reaching a maximum at the end of the day and decreasing on lying down.
- Erythema and skin tenderness.
- Cough and breathlessness, initially on exertion, later on breathlessness may be present at rest and on lying down when cardiac failure develops.
- Hepatomegaly (enlargement of liver).
- Eyes: fundus examination shows dilated, torturous vessels and superficial retinal haemorrhages. Bilateral (both eyes) glaucoma occurs in some cases (raised intra ocular pressure with normal chamber depth, no aqueous outflow obstruction, no sign of anterior segment inflammation).
- Pulmonary oedema, pericardial effusion, cardiac failure.
Epidemic dropsy is a clinical state caused by consuming the edible oil adulterated with Argemone mexicana seed oil that is a native plant of the West Indies, and grows wild in India. It has prickly leaves and bright yellow flowers. In India it is popularly known as Satyanashi.
Seeds of Argemone mexicana are black in colour and closely resemble mustard seeds. Crops of mustard oil are matured during March and at the same time seeds of argemone also mature hence there may be accidental mixing of both seeds. However intentional mixing of Argemone mexicana oil with mustard oil by unscrupulous traders can lead to large scale outbreaks.
Toxic effects of argemone oil are because of two physiologically active (benzophenanthridine) alkaloids-sanguinarine and dihydro-sanguinarine. Sanguinarine interferes with the oxidation of pyruvic acid that accumulates in the blood.
The outbreaks of epidemic dropsy occur usually in months of May to September in India because newly extracted oil is sold during these months in the market. Massage with contaminated mustard oil has also been reported to cause epidemic dropsy.
The diagnosis of epidemic dropsy may be considered during an outbreak of bilateral tender pitting leg oedema in more than one member of a family or community. It should be distinguished from hypoproteinaemic states, filariasis, venous insufficiency, Beriberi, hypothyroidism and nephrotic syndrome. Presence of sanguinarine in blood and urine confirms the diagnosis for epidemic dropsy.
- Blood examination: may show anaemia and pancytopenia, raised plasma pyruvate levels and presence of sanguinarine.
- Liver function tests: are usually normal.
- Kidney function tests: blood urea and creatinine may be raised if renal failure is present. Hypoalbuminaemia, raised alpha-2 globulin and reversal of albumin: globulin ratio may be found in some cases.
- Urinalysis: is usually normal but sanguinarine may be present.
- Chest X-ray: may show cardiomegaly, pulmonary oedema or pneumonia.
- Electrocardiogram: may show nonspecific ST segment, and T-wave changes or atrial or ventricular extrasystoles.
Detection of argemone seed with mustard seed:
- Adulteration of light-yellow mustard seeds (Brassica dompestris) by argemone seeds can be visually detected. However, argemone seeds are more similar in colour to the dark mustard seeds (Brassica nigra), and are thus less easily detected. Magnifying lens can be used for identification.
- The specific gravity of argemone seeds is 1.03 compared to 1.3 for mustard seeds. Hence, in normal saline solution, the mustard oil seeds settle at the bottom while argemone seeds remain suspended.
- Mustard seeds have smooth surface. The argemone seeds have grainy and rough surface and can be separated out by close examination. When mustard seed is pressed inside it is yellow while for argemone seeds it is white.
Detection of argemone oil adulteration in edible oils:
- Nitric acid test: Nitric acid is added to the sample of oil in a test tube. The test tube is shaken and development of yellow, orange-yellow or crimson colour shows the presence of argemone oil. The test is positive only when the concentration of argemone oil is >0.25%.
- Paper chromatographic method: It is the most sensitive method; can detect argemone oil up to 0.0001% in edible oil.
No specific treatment is there for the epidemic dropsy.
- Initial step is the withdrawal of contaminated oil.
- Bed rest with leg elevation and a protein rich diet.
- Supplements of calcium, antioxidants (vitamin C and E) and thiamine and other B vitamins are commonly used.
- Diuretics may be used but caution must be exercised not to deplete the intravascular volume unless features of frank congestive cardiac failure are present (as oedema is mainly due to increased capillary permeability).
- If pneumonia is there, it is treated with appropriate antibiotics.
- Cases with renal failure may need dialysis therapy.
- Glaucoma generally responds to medical treatment but may need operative intervention.
- Cardiac failure can be managed by bed rest, oxygen supplementation, diuretics, salt restriction and fluid restriction.
Mortality is seen in about 5% of cases and usually due to heart failure, pneumonia, respiratory distress syndrome or renal failure.
Various preventive measures to prevent outbreaks of epidemic dropsy:
Prior to purchase of refined vegetable oil, make sure that container should bear the label “free from Argemone Oil” along with other specifications mentioned under “The Food Safety and Standards (packaging and labelling) Regulations”
Use of unbranded and unpacked edible oil should be discouraged. In case of suspicion local health authorities/Chief Medical Officer may be informed so that unscrupulous dealers may be dealt with the strict enforcement of regulation.
Sensitization of farmers about accidental contamination of edible oil with argemone seeds; its consequences and prevention by de-weeding of argemone plants grown along with mustard plants should be encouraged.