The Northern Territory Disease Control Bulletin
Territory Health Services, Centre for Disease Control
Northern Territory disease control bulletin; E-Journals; PublicationNT; Northern Territory disease control bulletin
Date:1998-12; This publication contains may contain links to external sites. These external sites may no longer be active.; Made available via the Publications (Legal Deposit) Act 2004 (NT).
Communicable diseases; Reporting; Northern Territory; Statistics; Periodicals
Northern Territory Government
Northern Territory disease control bulletin
v. 5 no. 4
Attribution International 4.0 (CC BY 4.0)
Northern Territory Government
The Northern Territory Disease Control Bulletin Vol. 5 No. 4 December 1998 8 Ciguatera poisoning occurs throughout the tropical and subtropical waters of the Pacific, Indian and Atlantic Oceans and surrounding Seas. Outbreaks and sporadic cases occur in residents and visitors of these areas and also in unsuspecting persons far from tropical waters who have eaten fish transported from these areas. This was highlighted in a recent newspaper report of a group from Melbourne with alleged ciguatera poisoning.1 Ciguatera toxins are produced by dinoflagellates which are usually attached to algae growing in reef areas. The toxin is eaten by plant-eating fish who are in turn eaten by larger predatory fish who may be eaten by even larger fish. The toxin accumulates and concentrates in the fish, especially in the head, viscera (guts) and roe (eggs). The occurrence of the toxin is unpredictable but can be very localised eg, in one specific side or area of a reef. The toxin is usually associated with large (> 2 kg) predatory reef fish such as barracuda, coral trout, coral cod, trevally, grouper, mackerel and red emperor. In the NT, fish implicated in ciguatera poisoning have been caught around Bremer Island, Bonner Rocks, Miles Island, the Cape Arnhem area, north of Borroloola, at Nhulunbuy (Gove)2 and, for the first time, as reported above, from North East Island near Groote Eylandt. Deep sea fish eg tuna and dolphin are not known to carry ciguatoxins. The toxin does not harm the fish and cannot be removed by freezing, cooking or cleaning the fish. The toxin is colourless, odourless and tasteless. The fish does not look spoilt. There is no approved human assay for measuring ciguatera toxin and the diagnosis is based on having the characteristic signs and symptoms after eating large predatory reef fish. The symptoms usually come on 1 to 30 hours after eating the fish with the mean time being about 8 hours. The toxin can be tested for in samples of the fish - though often not in a timely fashion. Symptoms experienced are a combination of: 1. Acute gastrointestinal nausea and vomiting diarrhoea abdominal pain; 2. Neurological tingling and numbness around the lips, hands and feet muscle weakness headaches severe pruritus hot and cold reversal; and occasionally 3. Cardiovascular bradycardia hypotension respiratory depression. Additional general complaints include tiredness and joint pains. Neurological symptoms may be made worse by alcohol consumption, exercise, sexual intercourse and changes in dietary behaviour eg restricted diet or high-protein diet.3 The duration of the acute illness ranges from 1 to 8 days however neurological symptoms can last for months. There is no known antidote or antitoxin and therefore treatment is supportive and to relieve pain and discomfort. Administering IV mannitol has been reported by some to be effective as an early treatment4,5 but results from controlled trials are not available.3 General precautions need to be followed when living or travelling in areas known to have ciguatera toxin carrying fish and include: 1. Fish species which are locally implicated should be avoided. 2. Large warm water reef fish should be treated with suspicion (or avoided altogether eg barracuda) with no more than 250 grams of flesh being eaten at a first sitting. 3. Under no circumstances should the head, viscera or roe of reef fish be eaten. 4. People who develop symptoms of ciguatera poisoning should seek medical advice immediately. 5. Fisherman should avoid known implicated areas and vendors should not sell fish from those areas. There are public health actions to be taken when one case or an outbreak of ciguatera poisoning occurs. By notifying public health authorities as in the above outbreak further cases are avoided. Additionally, by gathering information on the number of incidents and the locations of ciguatera poisoning, the public, the departments of fisheries and medical services become more informed. Therefore the argument can be made, that like other foodborne illnesses with a public health response, ciguatera poisoning deserves consideration to
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