Published Date: 2009-01-29 09:01:06
Subject: PRO/EDR> Food poisoning, histamine, silkworms - Thailand (Sa Kaeo)
Archive Number: 20090129.0397

food POISONING, HISTAMINE, SILKWORMS - THAILAND (SA KAEO)
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Date: Wed 28 Jan 2009
Source: Asia One, The Nation/Asia News Network report [edited]
<http://health.asiaone.com/Health/News/Story/A1Story20090128-117714.html>

Some 118 people have fallen ill, with 60 being admitted to hospital, after consuming fried silkworm believed to [contain] the toxic substance histamine. Most of the patients suffered facial swelling, vomiting, blurred vision, numbness around the mouth, exhaustion, and skin rash, said the Public Health Ministry's epidemiologist, Anek Mong-oomklang. He presented the case at a 3-day conference entitled "Mobilize Epidemiology to Health Policy Development," organised by the Department of Disease Control. [Date of outbreak not given, possibly 2008. - Mod.JW]

Anek and his team studied the epidemiological effects of food poisoning by collecting samples of silkworm at the Rong-Klua market, a hub for insect trade, at the border province of Sa Kaeo.

After hearing that one of the employees of a shop importing insects from China had fallen ill from eating a fried silkworm, they sent the insects for laboratory tests and discovered that most of the silkworms sold in Rong-Klua market [contained] histamines. The level of histamine found in [a] silkworm was 875 milligrams per kilogram, when, according to US food regulations, no more than 50 mg/kg of histamine can be allowed in fish, which is [more] usually found contaminated [see ProMED refs. below. - Mod.JW]. This is the 1st time that an insect has been found contaminated by this substance, Anek said.

-- Communicated by: ProMED-mail <promed@promedmail.org>

[Foodborne histamine poisoning usually occurs as scombroid fish poisoning from the ingestion of histamine produced from histidine in certain poorly refrigerated fish. Typically, symptoms include facial flushing, sweating, rash, a burning or peppery taste in the mouth, diarrhea, hives, and abdominal cramps and usually resolve within several hours without medical intervention. More severe symptoms (such as respiratory distress, swelling of the tongue and throat, and blurred vision) can occur and require medical treatment with antihistamines.

The mechanism of how these silkworms became virtual histamine 'bombs' is unclear but a 2006 report from Viet Nam (<http://www.thanhniennews.com/healthy/?catid=8&newsid=13954>) could have been the same thing:

"Over 150 people in Viet Nam's Thanh Hoa province came down with poisoning from silkworms, a popular food in the country, bought at sidewalk vendors in the past week, a local expert said. Nguyen Dang Ngoan, director of the provincial Health Prevention Center said the incidence could be due to chemical preservatives mixed in the silkworms. Victims manifested headaches, giddiness, blurred vision, tissue inflammation and vomiting."

Sa Kaeo province is in southeastern Thailand and can be found on a map at <http://en.wikipedia.org/wiki/Sa_Kaeo_Province>. The HealthMap/ProMED-mail interactive map of Thailand is available at <http://healthmap.org/promed/en?g=1606807&v=13.817,102.067,5>. - Mod.LL]

[It is interesting to speculate that silkworm histamine content may be a protection against predators, just as some butterflies are poisonous to birds. - Mod.JW]

See Also

2008
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Scombroid poisoning, tuna - UK: (Scotland) 20081208.3852
2007
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Scombroid poisoning, tuna, 2006 - USA (LA, TN) ex Asia 20070820.2714
2005
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Scombroid poisoning, frozen fish - Israel: recall 20050610.1619
2002
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Scombroid poisoning, tuna - USA (PA): suspected 20020827.516
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