The magnitude of severe box jellyfish cases on Koh Samui and Koh Pha-ngan in the Gulf of Thailand

There were seven fatal box jellyfish cases in Thailand during the period 1999–2015. One death took place on Lanta island, Krabi Province. Six out of seven occurred on the islands of Pha-ngan and Samui which is the highest incidence of jellyfish related deaths in Thailand [11, 12, 14, 15]. This information is useful for convincing communities that the magnitude of the problem is high. Thai people and many local health personnel believe that the deaths may be due to a hypersensitivity of Caucasian people to jellyfish. A previous death of Swedish girl on March 2008 at a beach of Lanta Island, Krabi Province supports this belief. She was diagnosed as having anaphylactic shock from jellyfish contact. There were extensive tentacle marks all over her legs [12]. The nationalities of the probable box jellyfish cases in this study were varied. In addition to Caucasian people there were also Asian groups, including Chinese and Thai. In particular, the death of a Thai woman in this study was very high attention in the media and was of great public interest [14]. The diagnosis in this case was “Cardiac arrest with anaphylaxis following contact with a venomous animal”. Two of the reasons for misdiagnosis are lack of knowledge and misbelief. The authors with involving organizations have been gathering data to increase knowledge regarding box jellyfish in Thailand (Marine and Coastal Resources Research and Development Center of Marine and Coastal Resources, Department of Natural Resources and Environment Ministry, Surveillance and Rapid Response Teams, Regional Offices of Disease Prevention and Control National Science Museum, Phuket Marine Biology Center, Marine and Coastal Resources Research and Development Centers along the Gulf of Siam, government and private health services along the coasts of Thailand). However, information regarding various species of box jellyfish is not officially included the medical school curriculum yet. Nevertheless, some emergency medicine training courses and medical schools have started to include that knowledge from our text book [17]. The clinical manifestations of the female Thai victim were consistent with chirodropid envenomation. She collapsed and had no pulse within a few minutes. Her friends, who were also stung by the box jellyfish, removed the tentacles that were attached to her body and resuscitated her for about 20 min but there was no response. She was taken to a clinic nearby and received vinegar pouring and cardiopulmonary resuscitation (CPR). She did not respond and was transferred to a community hospital. After receiving CPR for an hour, she was declared dead at the community hospital. The time between being stung to receiving treatment by health personnel was about 20 min which was too long and she may well have died on the beach. Other cases in this study also had similar clinical manifestations which were indicative of chirodropid envenomations. One such case was the fatal sting of a German woman on October 6th, 2015. The injured individuals all suffered from tremendous pain after being stung and also had systemic reactions [2, 12]. They had difficulty breathing and had a very high heart rate. Thaikruea et al. [12] conducted the investigations and found that seven out of the eight cases collapsed and all of them had tentacle marks on their bodies.

Clinical observations support a dose dependency where envenomation severity is proportional to tentacle contact length. When the area of tentacle mark more than 50 % of extremity or the length of tentacle contact is more than 6–7 m the probability of death is high [2, 12]. In this study, most cases except the Australian male had wound areas of more than 50 % [11]. The remarkable signs were the wounds caused by the tentacles. From our observations, chirodropid envenomation associated dermatonecrosis differs from that caused by Pelagia spp. and Chrysaora spp. The brownish erythematous tentacle marks developed in a short period after being stung [12, 14, 16]. The wound was described by various professionals as “Frost-ladder like”, “Step ladder like”, “Ladder-like transverse band” or “whip marks” [5, 12, 14, 16, 18]. Thaikruea et al. [16] defined the term in Thai language as “caterpillar tracks” in order to educate the general population and health personnel in layman’s terms. The appearance of the wounds in the cases where the injuries were caused by Chirodropidae found in Thailand resemble the caterpillar tracks of the tanks which have articulated steel bands passing around the wheels. Sting site markings were typically 3–5 mm wide with approximate 1–2 mm long dermatonecrotic mark repeatedly interspersed by 1-3 mm of normal tissue. The length depend on tentacle contact lengths [12, 14, 16]. One great concern is that physicians who lack the relevant knowledge usually diagnose the box jellyfish stings as an allergic reaction or anaphylactic shock and treat the patients with antihistamine or steroid treatments. Steroids have no effect on dermatonecrotic toxin and may increase the probability of infection in the wounds. The treatment of the wound should be similar to those of fresh or burn wounds. Antibiotics can be used if necessary. In the later stages, steroids can be used if indicated [16].

The incidence of stings has increased in recent years. The higher incidence between July and October might be due to the seasonal life cycle of box jellyfish. The study of morbidity and mortality due to jellyfish envenomation from hospital data in the period from 1998 to 2002 indicated a high rate of incidence in the islands of Samui and Pha-ngan between August and October [19]. Another possible explanation is that this is high season for tourism on the islands. Logically, the more tourists there are on the islands, the more likely the contacts with jellyfish. The numbers of tourist are highest at the time of the full moon parties that are held each month on the night of the full moon on Rin beach, Pha-ngan island. In recent years, more parties have been occurring, including black moon and half moon parties. (http://www.fullmoonparty-thailand.com/; http://www.fullmoon.phangan.info/) These parties are of great concern to public health due to their popularity because many of the tourists become inebriated and swim in the dark sea. The beaches are very crowded and when incidents occur it is very difficult to recognize and rescue properly. It was on such an occasion that the latest death, that of the Thai female, occurred this year.

The majority of cases involved stinging by Chirodropidae. There are no experts or laboratory facilities to identify the toxin and species of box jellyfish in Thailand. The Epidemiology Bureau of Public Health Ministry established a collaborative agreement with the Faculty of Medicine, Chiang Mai University, Ministry of Education in 2008 [20]. The Australian experts have provided consultancy and the Marine and Coastal Resources Department of the Ministry of Natural Resources and Environment have joined the collaboration recently. Since then, the team has conducted outbreak investigations and studied the species of box jellyfish in Thailand. The latest results show that box jellyfish species may differ from those in Australia (Announcement in the meeting among key persons of stakeholder and government officers on Pha-ngan island on August 11, 2015).

Recently, there has been controversy about using vinegar for first aid to stop the firing nematocysts of box jellyfish when Seymour J from Queensland Tropical Health Alliance, School of Public Health and Tropical announced that vinegar induced the nematocysts to cause more venom to enter the body [21].Welfare et al. study only involved a battery stimulated tentacle, a placenta membrane and then various rinse solutions. There were no animal or human subjects. The results of this very small model was that vinegar led to a slight increase in recovery of very low (biologically irrelevant) levels of venom activity (at 1 μg/ml it was less than one hundredth of the native venom). The paper itself did not make wild claims, Jamie Seymour was quoted in the press releases as wildly exaggerating the findings to conclude that the small battery/membrane model indicated that “Vinegar can be deadly.” (Vinegar on jellyfish sting can be deadly: study. http://www.sbs.com.au/news/article/2014/04/08/vinegar-jellyfish-sting-can-be-deadly-study (accessed on 25 August 2015; Vinegar May Kill Rather than Cure Victims of Box Jellyfish Stings: Study. http://www.frenchtribune.com/teneur/1422205-vinegar-may-kill-rather-cure-victims-box-jellyfish-stings-study (accessed on 25 August 2015). These press release claims have not been supported by any other investigators and have been completely rejected by the entire scientific community. The study design and statistical validity has been criticized by Yanagihara and Chen [22]. Winkel K (director of the Australian Venom Research Unit, the University of Melbourne) expressed that there was not enough evidence to support this announcement. (http://www.cairnspost.com.au/news/cairns/scientists-salting-jcu-claims-vinegar-is-bad-for-jellyfish-stings/story-fnjpusyw-1226900575253) Ward et al. [23] concluded from their findings that vinegar made thing worse. However, Auerbach P disagreed because patients in the study received very small doses of vinegar, therefore, this conclusion was not valid. Furthermore, Auerbach P stated that based on his experiences in treating patients stung by box jellyfish he found that patients had good results when applying vinegar [15, 24]. Currently, the Australian Resuscitation Council and American Heart Association–American Red Cross International Consensus still recommend vinegar [13, 25]. Thaikruea et al. [12, 15, 20] found that the majority of near-fatal, or surviving cases in Thailand had vinegar poured onto the injuries as part of the first aid procedure, while the majority of the fatalities did not. In this study, only one of the fatal cases received vinegar as first aid but might be not appropriate. The fatality did not receive vinegar until 20 min after the sting. One fatal case in this study had fresh water poured on to the wounds and icepacks applied. It is now known that application of fresh water and ice cause greater firing of nematocysts, hence these treatments are contraindicated for first aid for box jellyfish stings [13, 25].

The incidents occurred more frequently in the southen part of Pha-ngan island which face the northern part of Samui island. However, the northern part and other areas also had incidents (data not shown for mild to moderate cases). Based on the experience of investigating the box jellyfish problem for this study on both Pha-ngan and Samui islands, it was found that people do not believe or do not know that the incidents are more prevalent than their perceptions. These perspectives were demonstrated at several meetings and workshops carried out over the past 7 years. After the death on July 31st this year, another severe case occurred on the island of Samui on September 12th 2015 at Chawang beach on Samui island. This occurred to a 31 year old Chinese male, who was stung by Chirodropidae. He lost consciousness and was admitted to Intensive Care Unit, requiring use of a respirator. He received vinegar as first aid at the hospital after 10–15 min being stung (Fig. 4). Stakeholders start to concern about this health problems and want to know more about the magnitude in these islands.