Aquagenic pruritus is a skin condition characterized by the development of severe, intense, prickling-like epidermal itching without observable skin lesions and evoked by contact with water. Presentation
Presentation varies from person to person. Some people have discrete attacks, which can last between 10 and 120 minutes while others are symptomatic almost constantly due to atmospheric humidity levels and/or sweating. Itching most frequently occurs on the legs, arms, chest, back, and abdomen, though it can also occur elsewhere.Itching on contact with water that also includes hives is known as aquagenic urticaria. Pathogenesis
The exact mechanism of the condition is unknown. Some studies have suggested the itching occurs in response to increased fibrinolytic activity in the skin, inappropriate activation of the sympathetic nervous system, increased activity of acetylcholinesterase, or an increase in mast cell degranulation that releases histamine and other chemicals into the body. Diagnosis
No definitive medical test is known for aquagenic pruritus. Rather, diagnosis is made by excluding all other possible causes of the patients itching, including polycythemia vera. Since pruritus is a symptom of many serious diseases, it is important to rule out other causes before making a final diagnosis. Treatment
Beta-Alanine, a nonessential amino acid and freely available as a nutritional supplement in many countries, has been found to suppress or significantly reduce the symptoms in many cases. Anecdotal evidence indicates that it is commonly consumed in doses of 750 mg to 2 grams before water contact.
Given that multiple people often consume food from the same source, it is common for more than a single person to be affected simultaneously. Symptoms usually appear 12–36 hours after eating, but can also appear within 6 hours to 10 days. Wound
Wound botulism results from the contamination of a wound with the bacteria, which then secrete the toxin into the bloodstream. This has become more common in intravenous drug users since the 1990s, especially people using black tar heroin and those injecting heroin into the skin rather than the veins. Wound botulism accounts for 29% of cases. Inhalation
Isolated cases of botulism have been described after inhalation by laboratory workers. Injection
Symptoms of botulism may occur away from the injection site of botulinum toxin. This may include loss of strength, blurred vision, change of voice, or trouble breathing which can result in death. Onset can be hours to weeks after an injection. This generally only occurs with inappropriate strengths of botulinum toxin for cosmetic use or due to the larger doses used to treat movement disorders. Following a 2008 review the FDA added these concerns as a boxed warning. Mechanism
The toxin is the protein botulinum toxin produced under anaerobic conditions (where there is no oxygen) by the bacterium Clostridium botulinum.