Papua New Guinea (PNG) is world famous for its biodiversity. Being an island nation, PNG is also famous for its diversity in marine life. Several species of turtles are present in PNG waters, some of which are on the endangered list and are therefore protected. However, turtle meat is a much sought after food among people living near the coast. Thus endangered species are sometimes killed for their meat. In some parts of the world, some turtle species are considered inedible (Campbell 1960), however, in most places in PNG, apparently all types of sea turtles are considered food.
Literature on turtle meat poisoning in PNG is limited. This may be attributed to the limited availability of medical journals in PNG to report cases. It may be also because instances of poisoning are not common. Until recently, the Papua New Guinea Medical Journal has been the only journal dedicated to publishing articles related to health issues in PNG. This journal has been in publication since the 1960s, initially as Papua and New Guinea Medical Journal and later as Papua New Guinea Medical Journal. Any report of cases of turtle meat poisoning would therefore be recorded in this journal if such incidents were noted in the past.
A recent report in the Post Courier (Post Courier, April 2009) about the death of several villagers in Manus after eating turtle meat prompted this review. Past issues of the P.N.G Medical Journal were reviewed to find out if cases were reported. This paper presents the results of the review discusses symptoms of turtle meat poisoning.
Method of review.
Past issues of the Papua New Guinea Medical Journal were obtained from the hospital library and reviewed. The author is based at a rural hospital and there is no Internet connection, therefore no literature search was done on online journals or database.
Results of review.
Twelve issues of Papua New Guinea Medical Journals were obtained dating between 1977-1960. Out of these, two articles were published relating to turtle meat poisoning. The first article by Campbell (1960) describes the signs and symptoms of turtle meat poisoning and mentions the possible turtle species that may cause poisoning. The second article by Dewdney (1967) reports the death of five villagers out of 43 people from the village of Namarodu in Namatanai, New Ireland Province, after the consumption of turtle meat. The article also presents possible turtle species that were eaten. The identification of the possible turtle species was made by experts in P.N.G, Australia, England and U.S.A from Kodachrome transparency copies of the turtle carapace.
Turtle species that were eaten resulting in poisoning.
In other parts of the world, the meat of the green sea turtle, Chelonia mydas, is consumed (Campbell 1960). In P.N.G, people consume all sea turtles (Kaptigau 2009, personal communication). The Hawksbill turtle, Eretmochelys imbricata, is reported as a common cause of turtle meat poisoning in Indonesia, India and the Philipines (Romeyn and Haneveld 1956, Campbell 1960). The Hawksbill turtle has a wide distribution from the Pacific and Indian Oceans to the Atlantic Ocean (Campbell 1960). It is the smallest of the marine turtles. The jaws of the turtle are hooked and curved like a beak. On the head are four prefrontal shields while the shields of the upper shell strongly overlap (Campbell 1960). There are usually two claws on each limp (Campbell 1960.
Dewdney (1967) made Kodachrome transparencies of the turtle carapace for identification by experts in P.N.G, Australia, Engalnd and U.S.A. It was concluded that the carapace of the turtle that caused the New Ireland epidemic in 1965 resembles the species Caretta caretta, Eretmochelys imbricata and Chelonia mydas, three of the four common species in PNG (Dewdney 1967).
Symptoms of turtle meat poisoning.
The consumption of Hawksbill turtle results in a distinct syndrome as described by Romelyn and Haneveld (1956) and reported by Campbell (1960). “The symptoms appear 12 hours after consumption of the meat and may consist of vomiting, dizziness, a burning sensation in the throat, headache, abdominal pain, and occasionally diarrhoea. After about two days the mucous membranes of the mouth and throat become swollen and swallowing is sometimes difficult. The papillae of the tip of the edges of the tongue swell and may remain enlarged for two months. Drowsiness may occur early. The patient may respond when spoken to but rapidly falls sleep again. Other nervous system signs may be present. The severity of the condition depends upon the amount of meat eaten. The mild cases show mouth and throat symptoms. In severe cases central nervous system signs are always present. The patient may remain unconscious for a week or more. The mortality in those cases which develop central nervous system signs is very high”. These symptoms are from consumption of the Hawksbill turtle meat.
The predominating symptoms from the New Ireland epidemic (Dewdney 1967) were as follows. Vomiting was the main complaint. Abdominal pain and diarrhoea were also present. Nervous system symptoms included muscle weakness, inco-ordination of movement, dysarthria, changes in or loss of consciousness, respiratory depression and finally death (Dewdney 1967).
Post-mortem examination on one patient showed no major pathology on naked eye examination (Dewdney 1967). None of the patients in the New Ireland epidemic complained of mouth or throat symptoms as described by Romeyn and Haneveld (1956). Although a microbial toxin was suspected in the cases reported by Dewdney (1956), the clinical picture was not typical of staphylococcal or clostrial contamination (Dewdney 1967). Furthermore, the absence of mouth and throat symptoms suggested an agent other than that reported by Romeyn and Haneveld (1956) (Campbell 1967). The current author has not sighted any medical report of the cases in Manus as reported in the Post Courier.
Turtle meat is a much sought meat after in Papua New Guinea and is eaten by most if not all who live along the coast. Yet reports of deaths or symptoms of poisoning after eating turtle meat is uncommon. The first published report of turtle meat poisoning is probably by Lagi (1932). He reports of an incident whereby inhabitants of an island in the then territory of Papua became ill after eating turtle meat (Lagi 1932). Campbell (1960) in questioning several people reports of only one man recalling an outbreak of illness near Samarai after turtle meat consumption. The current author is not aware of current literature on turtle meat poisoning in P.N.G in peer-reviewed journals apart from that reported in the Post Courier of April 2009.
From the articles reviewed it seems that consumption of Hawksbill turtle meat produces a distinct syndrome, although some symptoms such as vomiting and abdominal pain is common in other kinds of poisoning, for example, food poisoning. But other symptoms such as swollen mouth, tongue and throat seem be to exclusive to Hawksbill turtle meat poisoning. The presence of nervous symptoms such as unconsciousness, drowsiness and somnolence suggest the presence of a neurotoxin or a toxin that affects the nervous system.
The clinical features of the New Ireland epidemic in 1965 are not similar to those described by Romeyn and Haneveld (1956) and summarized by Campbell (1960). Notable, there was no swollen mouth, tongue or throat in the cases. However, there were features of nervous system involvement such as muscle weakness, inco-ordination of movement, dysarthria and changes and loss of consciousness (Dewdney 1967). Identification of the turtle species based on the turtle carapace was also inconclusive. Furthermore, the turtle meat was eaten after being cooked in a mumu that was opened more than 24 hours after being sealed (Dewdney 1967). The mumu was opened following heavy rain and the possibility of contamination by bacterial toxins was mentioned by Dewdney (1967) but was not conclusive.
Turtle meat is commonly consumed in PNG coastal villages with no reports of poisoning. The appearance of symptoms of poisoning after eating the meat of a turtle that is otherwise commonly eaten suggests the presence of a toxin that may not originate from the turtle. Indeed the variability of symptoms in the articles reviewed points toward this. The symptoms may be due to accidental consumption of poisonous coral or other vegetation consumed by the turtle as suggested by Romeyn and Haneveld (1956). It may also be that there may be yet an unidentified toxin in the turtles that is normally destroyed by cooking. The symptoms may be due to consumption of improperly cooked meat.
From the articles reviewed it is clear that consumption of turtle meat can cause poisoning. It is also clear that the consumption of Hawksbill turtle produces a characteristic clinical picture, the hallmark of which seem to be the appearance swollen mouth, tongue and throat. What was also common from the reports by Campbell (1969) and Dewdney (1967) is the presence of symptoms of nervous system involvement. Abdominal pain, vomiting and diarrhoea were also common. The origin of the toxin causing poisoning remains undetermined.