ciguatera toxin reef fish food poisoning

introduction

ciguatera poisoning is the 2nd most common chemical agent food poisoning after scombroid histamine food poisoning due to spoiled fish
it is caused by consumption of reef fish contaminated with ciguatoxin, which originates with certain dinoflagellates (algae) associated with coral reef systems and accumulates up the food chain from small herbivorous fish to larger carnivorous fish, such as barracuda and grouper.
G toxicus, which produces ciguatera toxin, tends to proliferate on dead or dying coral reefs
unlike scombroid histamine food poisoning due to spoiled fish it is not due to poor refrigeration
it is impossible to detect the presence of the toxin in the fish by smell, taste, or appearance
in the US, most outbreaks occur in tropical areas such as Hawaii and Florida, or travellers returning from the Caribbean where some regions have high rates up to 4% of households affected annually!
it is a major problem in Third World countries in the tropics and subtropics (between 35degree north and south latitudes)
it is thought that 50,000 cases occur globally each year

onset usually within 6-12 hours of eating reef fish (15min to 24hrs)
symptoms worsen over 4-6 hours after onset
GIT symptoms often appear first:
- abdo pain, nausea, vomiting, diarrhoea
- painful defecation
neurologic symptoms:
- irritability may be the main feature of children
- paraesthesiae - lingual, circumoral and painful paraesthesiae of the limbs
- metallic taste
- paradoxic temperature reversal (cold objects feel hot)
- dental pain and teeth may feel loose
- pruritus, arthralgias, myalgias, weakness
- ataxia, vertigo
- respiratory paralysis
- coma
cardiovascular:
- bradycardia
- hypotension
- acute pulmonary oedema
other features:
- chills, sweats
- painful ejaculation
- polymyositis

essentially clinical based on history of eating reef fish and the symptoms
a similar illness can be caused by eating fish which have fed on cyanobacteria which produce lyngbyatoxin (eg. tropical waters such as Moreton bay area Qld)

supportive care
activated charcoal may help in 1st 3-4hrs after ingestion
antiemetics
antihistamines (H1) for pruritus
iv fluids
?role of:
- early iv mannitol with strict fluid balance charting may reduce neurologic symptoms
- gabapentin (Neurontin) as for neuropathic pain
- large doses of vitamin B12
- monoclonal antibodies
avoid opiates and opioids and barbiturates