Biology Reference
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It seems unlikely that it will ever be possible to control phytoplankton
composition in growing areas, eliminating toxigenic species, and there is
no reliable way to forecast, when a particular phytoplankton will grow
and thus no way to predict blooming of toxigenic species (Hall, 1991).
Removal of toxin by depuration techniques may have some potential, but
the process is very slow and costly. There is also a risk that a small number
of individuals decline to open and pump clean water through the system
and therefore retain their original level of toxicity (Hall, 1991).
Histamine poisoning is a chemical intoxication following the ingestion
of foods that contain high levels of histamine. Historically this poisoning
was called scombroid fi sh poisoning because of the frequent association
with scombroid fi shes including tuna and mackerel. Histamine poisoning
is a worldwide problem occurring in countries where consumers ingest
fi sh containing high levels of histamine. It is a mild disease; incubation
period is very short (few minutes to few hours) and the duration of illness
is short (few hours). The most common symptoms are cutaneous such as
facial fl ushing, urticaria, edema, but the gastrointestinal tract may also be
affected (nausea, vomiting, diarrhea) as well as neurological involvement
(headache, tingling, burning sensation in the mouth). Histamine is formed
in the fi sh post mortem by bacterial decarboxylation of the amino acid
histidine as shown in Figure 4.5.
Fig. 4.5 Conversion of histidine to histamine by histidine decarboxylase
The fi sh frequently involved are those with natural high content of
histidine such as those belonging to the family Scombridae but also non-
scombroid fi sh such as Clupeidae and mahi-mahi may be involved in
histamine poisoning.
The histamine-producing bacteria are certain Enterobacteriaceae ,
some Vibrio sp., a few Clostridium and Lactobacillus sp. The most potent
histamine producers are Morganella morganii, Klebsiella pneumoniae and
Hafnia alvei (Stratten and Taylor, 1991). These bacteria can be found on
most fi sh, probably as a result of post-harvest contamination. They grow
well at 10°C but at 5°C growth is greatly retarded and no histamine was
produced by M. morganii when temperatures were <5°C at all times
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