Part F | 33.5
798 Part F Marine Derived Metabolites
Treatment
Treatment is primarily supportive. Intravenous mannitol was thought to be the most promising of the pharmacotherapy treatments; however, it has experienced
a relative decline in acceptance after a randomized,
double-blind trial in 2002 failed to confirm its efficacy [33.79–81]. However, with recent case reports
supporting its use and a better understanding of ciguatera poisoning, many experts in the field believe that the
use of mannitol for the treatment of acute ciguatera poisoning arguably deserves revisiting [33.79, 82].
33.5.2 Human Shellfish Poisoning
Toxic illness caused by shellfish has been recognized
for several hundred years. Native Americans are known
to have warned early settlers to avoid shellfish during the summer months, as red tide is favored by
warmer weather. Molluscan shellfish are filter feeders
and continually pump water through their gills where
particulate matter is removed and ingested. Mussels ingest food particles of any type of 290 mm in size with
a rate of ingestion dependent on water temperature and
environment. Optimally, they can filter 2:5 L h
1 , extracting 98% of the available algae. Consequently, any
toxin associated with the phytoplankton ingested can
rapidly accumulate and hence become concentrated in
the bivalve mollusk. Bivalve mollusks such as clams,
scallops, oysters, and mussels that filter feed on toxic
algae can accumulate large amounts of toxins in their
tissues, posing a toxic threat to humans who make
shellfish a part of their diet. Shellfish are usually unaffected by toxic algae themselves but can accumulate
toxins in their tissue to levels that can be lethal to
humans. High concentrations of marine biotoxins in
these animals can cause illness amongst people who
eat contaminated shellfish. Shellfish that have fed on
toxic dinoflagellates retain the toxin for varying periods of time depending on the shellfish. Some clear the
toxin very quickly and are only toxic during the actual bloom. Others retain the toxin for a long time,
even years. The most serious threat posed to human
health by marine toxins is through shellfish contamination. The consumption of these toxic shellfish by
humans causes illness, with symptoms ranging from
mild diarrhoea and vomiting to memory loss, paralysis,
and death. Illnesses that result from marine biotoxins
are not related to the manner in which food is handled or prepared, but the exposure that shellfish has
to microscopic organisms while living in the marine
environment.
Several forms of shellfish poisoning may occur after ingesting filter-feeding bivalve mollusks such as
mussels, oysters, clams, scallops, and cockles, or crustaceans such as crabs and lobsters that accumulate
potent marine toxins produced by single-celled microscopic marine algae (dinoflagellates or diatoms) associated with algal blooms or red tides. The most common medical problems resulting from marine biotoxins,
are the human shellfish poisoning syndromes PSP,
NSP, DSP, and AZP. These poisoning syndromes
are distinctly clear and the cases can be serious
(Table 33.2).
Paralytic Shellfish Poisoning (PSP)
PSP of humans is caused by the consumption of shellfish that have been contaminated with STXs. Blooms of
neurotoxic dinoflagellates from several genera result in
outbreaks of PSP, probably the most widespread of the
poisoning syndromes [33.83]. PSP is not only the most
common form of shellfish poisoning, but it is also the
deadliest, with a mortality rate of 6% worldwide (higher
in developing countries) [33.84–86]. PSP usually occurs in outbreaks and is observed most commonly in
recreational diggers.
Source
Filter-feeding bivalve molluscs (e.g., oysters, mussels, clams) nonbivalve shellfish (whelks, moon snails,
and dogwinkles) or tomalley of crustaceans (crabs,
lobster).
Prevalence
Clinically documented PSP outbreaks with several
dozen to around 200 patients have been described in
Western Europe, Taiwan, and Guatemala. Cases have
also been described in Massachusetts and Alaska. Between 1927 and 1985, 505 PSP cases were recorded
in California, of which 32 ended fatally. In contrast,
in 10 PSP epidemics in the USA between 1971 and
1977, there were no recorded fatalities. 2/116 died
in an epidemic in Taiwan. In September 1997, an
outbreak of PSP was reported in Vizhinjam, Kerala, resulting in the death of 7 persons and hospitalization of over 500, following consumption of the
mussel, Perna indica [33.87]. Recently, in September 2004, an unusual nauseating smell emanating from
the coastal waters was recorded in Kollam to Vizhinjam on the southwest coast of India. More than 200
persons, especially children, complained of nausea
and breathlessness for a short duration due to the
smell.
798 Part F Marine Derived Metabolites
Treatment
Treatment is primarily supportive. Intravenous mannitol was thought to be the most promising of the pharmacotherapy treatments; however, it has experienced
a relative decline in acceptance after a randomized,
double-blind trial in 2002 failed to confirm its efficacy [33.79–81]. However, with recent case reports
supporting its use and a better understanding of ciguatera poisoning, many experts in the field believe that the
use of mannitol for the treatment of acute ciguatera poisoning arguably deserves revisiting [33.79, 82].
33.5.2 Human Shellfish Poisoning
Toxic illness caused by shellfish has been recognized
for several hundred years. Native Americans are known
to have warned early settlers to avoid shellfish during the summer months, as red tide is favored by
warmer weather. Molluscan shellfish are filter feeders
and continually pump water through their gills where
particulate matter is removed and ingested. Mussels ingest food particles of any type of 290 mm in size with
a rate of ingestion dependent on water temperature and
environment. Optimally, they can filter 2:5 L h
1 , extracting 98% of the available algae. Consequently, any
toxin associated with the phytoplankton ingested can
rapidly accumulate and hence become concentrated in
the bivalve mollusk. Bivalve mollusks such as clams,
scallops, oysters, and mussels that filter feed on toxic
algae can accumulate large amounts of toxins in their
tissues, posing a toxic threat to humans who make
shellfish a part of their diet. Shellfish are usually unaffected by toxic algae themselves but can accumulate
toxins in their tissue to levels that can be lethal to
humans. High concentrations of marine biotoxins in
these animals can cause illness amongst people who
eat contaminated shellfish. Shellfish that have fed on
toxic dinoflagellates retain the toxin for varying periods of time depending on the shellfish. Some clear the
toxin very quickly and are only toxic during the actual bloom. Others retain the toxin for a long time,
even years. The most serious threat posed to human
health by marine toxins is through shellfish contamination. The consumption of these toxic shellfish by
humans causes illness, with symptoms ranging from
mild diarrhoea and vomiting to memory loss, paralysis,
and death. Illnesses that result from marine biotoxins
are not related to the manner in which food is handled or prepared, but the exposure that shellfish has
to microscopic organisms while living in the marine
environment.
Several forms of shellfish poisoning may occur after ingesting filter-feeding bivalve mollusks such as
mussels, oysters, clams, scallops, and cockles, or crustaceans such as crabs and lobsters that accumulate
potent marine toxins produced by single-celled microscopic marine algae (dinoflagellates or diatoms) associated with algal blooms or red tides. The most common medical problems resulting from marine biotoxins,
are the human shellfish poisoning syndromes PSP,
NSP, DSP, and AZP. These poisoning syndromes
are distinctly clear and the cases can be serious
(Table 33.2).
Paralytic Shellfish Poisoning (PSP)
PSP of humans is caused by the consumption of shellfish that have been contaminated with STXs. Blooms of
neurotoxic dinoflagellates from several genera result in
outbreaks of PSP, probably the most widespread of the
poisoning syndromes [33.83]. PSP is not only the most
common form of shellfish poisoning, but it is also the
deadliest, with a mortality rate of 6% worldwide (higher
in developing countries) [33.84–86]. PSP usually occurs in outbreaks and is observed most commonly in
recreational diggers.
Source
Filter-feeding bivalve molluscs (e.g., oysters, mussels, clams) nonbivalve shellfish (whelks, moon snails,
and dogwinkles) or tomalley of crustaceans (crabs,
lobster).
Prevalence
Clinically documented PSP outbreaks with several
dozen to around 200 patients have been described in
Western Europe, Taiwan, and Guatemala. Cases have
also been described in Massachusetts and Alaska. Between 1927 and 1985, 505 PSP cases were recorded
in California, of which 32 ended fatally. In contrast,
in 10 PSP epidemics in the USA between 1971 and
1977, there were no recorded fatalities. 2/116 died
in an epidemic in Taiwan. In September 1997, an
outbreak of PSP was reported in Vizhinjam, Kerala, resulting in the death of 7 persons and hospitalization of over 500, following consumption of the
mussel, Perna indica [33.87]. Recently, in September 2004, an unusual nauseating smell emanating from
the coastal waters was recorded in Kollam to Vizhinjam on the southwest coast of India. More than 200
persons, especially children, complained of nausea
and breathlessness for a short duration due to the
smell.