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ABSTRACT:

Fish is a very common and tasty food and at the same time very nutritious too. There have been many cases of food poisoning after intake of poisonous fishes. Here we report one such case where 8 people got admitted to V.S.S. Medical College Hospital, Burla after consuming some kind of fish developed signs and symptoms of tetrodotoxin food poisoning. Among those 8 patients 2 of them expired.

KEYWORDS:
Food poisoning, Ich thyotoxicosis, Tetrodotoxin, Puffer fish

INTRODUCTION:
Fish is a very delicious food throughout the world, which is widely consumed. There are two categories of fishes-marine and fresh water. Few people know about the toxins present in the fish of both categories. The poisonous fishes are morphologically different from other edible fishes. The study of toxin of fish is known as Ichthyotoxicosis which is an important part of food poisoning. It is very important to know the toxins present in the fish so that fish can be taken as healthy food.

Here is an important case of food poisoning consumed by local tribals and admitted to V.S.S. Medical College Hospital and the end result is described below.

CASE REPORT:
On 18/10/2007 total eight people came to casualty around 8.30PM with history of taking one kind of fish in a social function. Locally known as “Fukka” and their signs and symptoms which developed within half an hour of intake such as paresthesia, vomiting, abdominal pain, breathlessness, dysphagia and extreme weakness of 4 limbs. In past history there was no history suggestive of diabetes mellitus, hypertension, sickle cell disease, bronchial asthma. In personal history there was no history of any addiction and they were from poor socioeconomic status.

The common clinical signs presented in such patient are respiratory rate: 25-30/min, BP - 100/70 to 110/80 mm of Hg , Pulse rate- 96- 104 /min regular and low volume. Per abdominal examination no abnormality detected. Chest examination bilateral vesicular breath sound and no added sound. Cardiovascular examination revealed first and second heart sounds normal and no murmur heard. The central nervous system examination revealed patients irritable and anxious with ptosis (B/L), pupils (B/L) normal in size and normally reacting to light, tone of the muscles of limb decreased and power of muscles of limbs Grade 2, plantar no response (B/L) and no meningeal signs.

On investigation of the patients Hb – 10-12gm%, ESR - 6 -10 mm (1st hour) DC, TLC within normal limit. Serum creatinine 0.8 – 1.0 mg/dl, blood urea 26-34 mg/dl, serum Na+ 136-140 meq/L, Serum K+ 4.0 – 4.6meq/L, urine routine and microscopic examination within normal limit. Random blood glucose 140mg/dl and ECG within normal limit.

The following treatment was given like stomach wash with KMno4, Oxygen inhalation, injection atropine and injection neostigmine alternately every 15 minute, injection ceftriaxone and injection hydrocortisone (100mg) IV 8 hourly, injection deriphylline 1 ampoule IM 8 hourly, injection ranitidine 1 ampoule IV 8 hourly, IV fluids, cathetrization of bladder and ryles tube were administered under sterile technique.


Course of treatment:
Out of 8 patients 2 became very serious like respiratory distress with laboured and hurried respiration along with frothing from mouth and coarse crepitations heard bilateral in lung fields. The 2 patients became stuporous leading to coma and death at 8 AM next day in spite of cardiopulmonary resuscitation. The signs and symptoms of other 6 improved gradually and they had an uneventful recovery and were discharged after 4 days.

Postmortem findings:
The two cases were subjected to medicolegal autopsy and the autopsy findings were:

External features: Face livid, frothy, blood tinged discharges from nostrils, eye closed, pupil dilated and fixed, nail bed cyanosed, rigor mortis all through the limbs.

Internal features: In both case stomach contained 100ml of brownish liquid, the mucus membrane were congested without excoriation. Liver, spleen, kidney were intensely congested. Right chamber of heart contained clotted blood and left chamber empty, great vessels were empty. The cause of death was established as asphyxia as a result of respiratory failure.

The final cause of death was pending chemical examination of visceras. For that stomach with its content, 500 gm of liver, intestine 30 cm and half of each kidney were preserved in saturated solution of common salt and handed over the police to further transmission to chemical examination.

The relative were advised to bring the particular fish which they have consumed and the fish was identified as puffer fish (Photo 1, 2).


DISCUSSION:
The fish consumed by eight people were identified to be Puffer fish after morphological examinations of the fish they have brought. Its local name is “Fukka”. In Japan a local variety of Puffer fish called “Fugu” is considered a delicacy but it requires special training and licensing of preparation as they are poisonous1. These fishes contain a toxin known as tetrodotoxin which is a heat stable, non protein neurotoxic predominantly concentrated in ovaries, kidneys , fish skin, muscles and intestine of Puffer fish2. Describing in detail tetrodotoxin is water soluble and its chemical nature is aminoperhydroquanizole1.

The ovary’s high concentration of the toxin renders female more poisonous during spawning season7. The toxin can be detected by mouse bioassays and fluroscent spectrometry1. The tetrodotoxin resembles another toxin called saxitoxin, from which it is distinguished by heat stability up to 1000C in acidic medium5.

The action of tetrodotoxin is more prolonged but saxitoxin is more neurotoxic5. Neurotoxicity of tetrodotoxin is due to inhibition of sodium potassium pump activity and blockade of neuromuscular inhibition1. The blockade at motor end plate is competitive and reversible2.

The clinical features of tetrodotoxin fish poisoning begins shortly after ingestion (10-45min) such as paresthesia of the lips, face , toes and fingers, vomiting, light headedness, feeling of doom, diaphoresis, dysphagia and dysarthria2. Buccal bullae, salivation, cranial nerve palsies and even convulsion have been reported1. An ascending paralysis develops with respiratory paralysis as a preterminal event (6-24 hours) of post ingestion2. In serious poisoning hypotension, cardiac dysarythmias like bradycardia were also observed1.

Diagnosis is mostly done from history and clinical presentation and treatment is mostly symptomatic and supportive7. Removal of toxin by stomach wash, IV edrophonxium or IM neostigmine restores muscle strength2. Airway intubation and ventilators are necessary if patients develops respiratory paralysis6. Studies have shown that mortality has approached 60%2.

Burla is situated on the bank of river Mahanadi. In past 2 years zoologist have found out that in river Mahanadi and its tributaries there is increase in tetrodotoxin containing fishes which were not seen 10 years ago. This is because of favourable temperature and pH of water of Mahanadi and its tributaries that caused an explosion of population of puffer fishes. This is because of construction of various factories in nearby areas for which the flora and fauna of Mahanadi river is getting rapidly destroyed and along with there is decreased species of fresh water fishes in resorvior (Dainik Samaj 01/11/2007).

CONCLUSION:
In spite of fish being a very much proteinous food it can kill human beings with its toxins as described above. It is a staple food in costal districts of Orissa, which cannot be replaced with any other food because it contains excellent and excessive protein. So we have to take some prevention for abetting the toxin found in the fish.

Tips to prevent fish poisoning:
1. Avoid eating large tropical fish like shark, barracueda, red snapper, dear bass etc5.
2. Do not consume fish that are likely to have decomposed i.e. fish that have not been stored or preserved properly5.
3. Do not eat the viscera of fish (particularly liver and gonads). See that the fish is properly cleaned and cooked5.
4. It has been suggested that suspect fish be first fed to a cat. If the cat dies within 8 hours, it is an explicit indication that fish is toxic5.
5. Do not eat unidentified fishes.
BIBLIOGRAPHY:
1. Gold Frank’s Toxicologic Emergencies, 6th Edition, P 1169-1170 by Lewis R Goldfrank, Neal E Flomenbaum, Richard S Weisman, Mary Ann Howland, Rober S Hoffmann, Neal A Lewin.
2. Medical Toxicology Diagnosis and Treatment of human poisoning Pg 1197-1198 by Mathew J Ellenhorn , Donald G Barcelous.
3. Modi’s Medical Jurisprudence and Toxicology, 23rd Edition by K Mathiharan & Amrit K Pattnaik.
4. Modern Medical Toxicology by V.V. Pilli.
5. Mosher HS, Fuhrman FA, Buchwald HD et al; Tarichatoxin – tetrodotoxin , A potent neurotoxin science 1964; 44; 100-1110.
6. Sims JK, Ostman DC, Puffer Fish poisoning : Emergency diagnosis and management of mild human tetrodotoxication: Ann Emerg Med 1986; 15:1094-1098.
7. Torda TA, Sinclair E, Ulyatt DB, Puffer fish (Tetrodotoxin)poisoning clinical records and suggested management. Med J Aug 1973; 1: 599-602.