Epidemic dropsy is a form of edema of extremities due to poisoning by Argemone mexicana (Mexican prickly poppy).
Epidemic dropsy is a clinical state resulting from use of edible oils adulterated with Argemone mexicana seed oil.
Sanguinarine and dihydrosanguinarine are two major toxic alkaloids of argemone oil, which cause widespread capillary dilation, proliferation and increased capillary permeability. When mustard oil is adulterated deliberately (as in most cases) or accidentally with argemone oil, proteinuria (specifically loss of albumin) occurs, with a resultant edema as would occur in nephrotic syndrome.
Other major symptoms are bilateral pitting edema of extremities, headache, nausea, loose bowels, erythema, glaucoma and breathlessness.
Leakage of the protein-rich plasma component into the extracellular compartment leads to the formation of edema. The haemodynamic consequences of this vascular dilatation and permeability lead to a state of relative hypovolemia with a constant stimulus for fluid and salt conservation by the kidneys. Illness begins with gastroenteric symptoms followed by cutaneous erythema and pigmentation. Respiratory symptoms such as cough, shortness of breath and orthopnoea, progressing to frank right-sided congestive cardiac failure, are seen.
Mild to moderate anaemia, hypoproteinaemia, mild to moderate renal azotemia, retinal haemorrhages, and glaucoma are common manifestations. There is no specific therapy. Removal of the adulterated oil and symptomatic treatment of congestive cardiac failure and respiratory symptoms, along with administration of antioxidants and multivitamins, remain the mainstay of treatment. Several lines of evidence have been shown to explain the mechanism of toxicity of argemone oil/alkaloid. The toxicity of sanguinarine has been shown to be dependent on the reactivity of its iminium bond with nucleophilic sites like thiol groups, present at the active sites of the enzymes and other vital proteins and thus suggesting the electrophilic nature of the alkaloid.
Pulmonary toxicity: The decrease in glycogen levels following argemone oil intoxication could be due to enhanced glycogenolysis leading to the formation of glucose-1-phosphate, which enters the glycolytic pathway resulting in accumulation of pyruvate in the blood of experimental animals and dropsy patients. The enhancement of glycogenolysis can further be supported by the interference of sanguinarine in the uptake of glucose through blocking of sodium pump via Na<sup>+</sup>-K<sup>+</sup>-ATPase and thereby inhibiting the active transport of glucose across the intestinal barrier. It is well established that increased pyruvate concentration in blood uncouples oxidative phosphorylation, and this may be responsible for thickening of interalveolar septa and disorganized alveolar spaces in lungs of argemone oil-fed rats and the breathlessness as has been observed in human victims.
Delayed clearance: Destruction of hepatic cytochrome P450 significantly affects the metabolic clearance by liver. The retention of sanguinarine in the gastrointestinal (GI) tract, liver, lung, kidney, heart and serum even after 96 hrs of exposure indicates these as the likely target sites of argemone oil toxicity. who reported four cases of poisoning in Calcutta in 1877 from the use of this oil in food.
Since then, epidemic dropsy has been reported from Bengal, Bihar, Orissa, Madhya Pradesh, Haryana, Assam, Jammu and Kashmir, Uttar Pradesh, Gujarat, Delhi and Maharashtra, mainly due to consumption of food cooked in argemone oil mixed with mustard oil or occasionally by body massage with contaminated oil.
Even after that the epidemics occurred at alarming frequency in Gwalior (2000), Kannauj (2002) and Lucknow (2005) cities of India. 6 possible cases with 2 deaths were reported in Gundari village in Banaskantha district of Gujarat in India were reported in June 2021.