What is Ciguatera Toxicity (Foodborn Illness Caused by Eating Fish Contaminated with Ciguatoxin)?
Ciguatera poisoning, which is very common worldwide, happens when you eat fish that has been infected with a toxic substance called ciguatoxin. This toxin is made by microscopic organisms called dinoflagellates, mainly found in warm waters around the globe. The toxin gets into fish when they eat these dinoflagellates and builds up in larger fishes that eat these smaller ones. People can get sick when they eat these infected fish. Common fish types known to cause this are barracudas, groupers, moray eels, amberjacks, sea bass, sturgeons, parrotfish, surgeonfish, and red snappers.
Ciguatoxin can cause many symptoms such as stomach upset, neurological problems, heart issues, and skin problems. Although it is rarelyfatal, it can be very unpleasant. Symptoms might not show up right away, often taking several days to develop. This means that people might start to feel ill after they’ve traveled from the place they ate the contaminated fish, and it is also possible for infected fish to be sold in areas where the illness is not normally found.
The conversation between two nerve cells, or neurons, happens at a place called the synapse. Each neuron is made up of three main parts: the soma or body of the cell, the axon which is a long part that connects to other cells, and the dendrites, which are short branches that reach out to other cells. The communication is possible by the transmission of chemicals known as neurotransmitters, which are released from the presynaptic terminals located at the ends of the axons or dendrites. These chemicals travel across the tiny gap at the synapse to reach the next, or postsynaptic, neuron.
The presynaptic membrane, which covers the terminals, plays a vital role in this process by containing channels that allow calcium ions to enter the neuron. This triggers the release of neurotransmitters into the synapse. These chemicals then bind to receptors on the postsynaptic cell membrane, generating a response in that cell. This might involve exciting the neuron (making it more likely to transmit a signal) or inhibiting it (making it less likely), depending on the type of neurotransmitter and receptor.
There are different types of nerve fibers in the spinal cord. Some have a layer of fatty tissue called myelin, which helps electrical signals travel more quickly along the nerve. Others don’t have this layer and transmit signals more slowly. The nerve fibers are grouped into different categories based on their size and speed. Type A fibers are myelinated and among them, Aα fibers are the largest and quickest at transmitting signals. They’re mainly associated with controlling muscle movement. Type C fibers are the smallest and slowest, and are mostly associated with sensing pain and temperature.
What Causes Ciguatera Toxicity (Foodborn Illness Caused by Eating Fish Contaminated with Ciguatoxin)?
Eating seafood that contains ciguatoxin can cause ciguatera poisoning. The chances of this happening are higher in the warmer months, especially from May to August in the northern hemisphere, as this is when the small organisms known as phytoplankton grow the fastest. However, with climate change causing warmer ocean temperatures and high levels of carbon dioxide in the water, phytoplankton and algal blooms can occur any time of the year. So, outbreaks of ciguatera poisoning can take place even during colder seasons. Additionally, rising sea temperatures allow the marine species carrying the ciguatoxin to thrive in places where they previously couldn’t.
Because of a process called bioaccumulation, where toxins build up in an organism, tropical predator fish like barracudas, groupers, eels, snapper, and amberjacks are most likely to cause ciguatera toxicity. However, more than 400 species of reef fish have also been found carrying ciguatoxin. The poison can be found in any part of the fish, and even very small concentrations, as low as 0.1 parts per billion in the fish’s flesh, can make people sick.
The problem is, ciguatoxin doesn’t have a taste or a smell, and it dissolves in fats, not water. It’s also resistant to heat, so it can’t be destroyed by cooking. This means that it can go unnoticed. People who eat seafood may accidentally ingest the toxin without realizing, unless they are aware of reported toxic algal blooms in the area.
Risk Factors and Frequency for Ciguatera Toxicity (Foodborn Illness Caused by Eating Fish Contaminated with Ciguatoxin)
Ciguatera toxicity, a nonbacterial fish poisoning, is a global phenomenon and is considered the most common of its kind. Each year, it affects between 50,000 to 500,000 people around the world. However, the actual number may be higher as it’s likely that many cases go unreported. The risk of exposure to this poisoning increases when people eat certain parts of highly contaminated fish. Although it can cause symptoms lasting from a few weeks to several years, the condition has a very low mortality rate of less than 1%.
Ciguatera poisoning is most commonly found in the South Pacific and Caribbean regions, but it has also been detected in marine species in the Indian Ocean. There are many types of ciguatoxin, but the most common are Pacific and Caribbean ciguatoxin-1. Interestingly, Pacific ciguatoxin-1 is known to be 10 times more toxic than its Caribbean counterpart.
Signs and Symptoms of Ciguatera Toxicity (Foodborn Illness Caused by Eating Fish Contaminated with Ciguatoxin)
Ciguatera poisoning happens when a person eats fish that contains harmful toxins. It is diagnosed through examining the patient’s symptoms and taking a detailed health and recent activity history. There are no lab or imaging tests that can confirm this condition.
Symptoms of ciguatera poisoning usually start within 1-2 days after eating the contaminated fish and include:
- Diarrhea
- Abdominal pain
- Nausea and vomiting
- Discomfort in the stomach
- Burping
These symptoms can appear as soon as 30 minutes or delayed up to 48 hours after eating the bad fish. In most cases (90%), these symptoms start within 12 hours and diarrhea usually lasts for about 5 days.
Neurological symptoms such as numbness in the mouth, hands, and feet, head pain, dizziness, convulsions, numbness around the mouth, a metallic taste in the mouth, blurred vision, itchiness, tremors, and even hallucinations are also common. Some patients, experiencing severe ciguatera toxicity, may feel a burning sensation when touching cold objects.
Skin symptoms like itchiness, hive-like rashes, and peeling or blistering of the skin have also been reported. Itchiness is severe in many (50-65%) cases and can be worsened by drinking alcohol.
Heart symptoms are quite rare but can include slow heartbeat, low blood pressure, and irregular heart rhythms. Patients should be asked if they experience heart palpitations, lightheadedness, and shortness of breath. These heart symptoms usually occur only in the early stages of the disease and get better over time.
In severe cases, the ciguatera poison has been associated with complications related to sexual and pregnancy health. For example, some women have reported painful intercourse after being in contact with a partner who had ciguatera toxicity. This may suggest that the toxin can be passed through semen. Pregnant women who get ciguatera poisoning may experience unnatural baby movements and an increased risk of preterm labor or miscarriage. Lastly, breastfeeding mothers can pass the symptoms to their infants, who may then experience diarrhea and facial rashes.
Patients may also report additional symptoms like muscle and joint pain, painful urination, excessive salivation, and sleep issues.
Most people with ciguatera poisoning get better within a few days or weeks, but some may have symptoms for years. Drinking alcohol during the time the person ingested the toxin can increase the risk of slow heartbeat, low blood pressure, and altered skin sensation. Instances of the disease coming back might be triggered by consuming alcohol, nuts, seeds, fish, chicken, and eggs.
Taking a detailed history, including the patient’s travel and social activities, food consumption, and performing a thorough physical examination are important steps in diagnosing this condition. Special attention should be given to examining the patient’s gastrointestinal, heart, muscle, skin, and pelvic areas (for those reporting symptoms related to the genitals or urinary system).
Testing for Ciguatera Toxicity (Foodborn Illness Caused by Eating Fish Contaminated with Ciguatoxin)
There are several tests that can detect ciguatoxin, a toxin that may cause food poisoning, including liquid chromatography-mass spectrometry, cytotoxicity assays, and receptor-binding immunoassays. However, these tests are often used for academic or research purposes and are typically not available for regular clinical use. Also, these tests may take several days to give results, making them unsuitable for emergency hospital visits.
Routine tests often don’t give specific results, but they can be useful for tracking the effects of ciguatoxin in the body. For example, metabolic panels can assist in identifying fluid and electrolyte imbalances that may be caused by stomach symptoms. Fecal tests might not display disease-causing organisms. An electrocardiogram, which records the electrical activity of the heart, can help detect abnormalities in heart rhythm in patients having heart-related symptoms.
Imaging tests can be used to rule out brain lesions if there are signs of neurological abnormalities during the physical exam. The selection of diagnostic exams should be guided by the patient’s symptoms.
Treatment Options for Ciguatera Toxicity (Foodborn Illness Caused by Eating Fish Contaminated with Ciguatoxin)
Treatment for ciguatera poisoning primarily involves managing the symptoms because there isn’t a specific cure for the toxin. If nausea and vomiting occur, medicines such as ondansetron or other similar drugs can be used. Drugs to stop diarrhea may also be given. Dehydration could also set in due to vomiting and diarrhea, and so patients should increase their fluid intake. If they can’t drink water, fluid should be provided directly through their veins.
For itchiness, antihistamines and a medication called amitriptyline can be considered. Taking cold showers might also provide temporary relief from skin burning and itchiness. Non-steroidal anti-inflammatory drugs can help manage pain in the bones and muscles. It has been suggested that gabapentin and amitriptyline can also be used to treat nerve problems associated with ciguatera poisoning. If persons develop seizures, they should be treated with benzodiazepines, and where these are inadequate, barbiturates or propofol can be used.
Symptoms caused by nerve damage may get worse with alcohol or heavy exercise. As such, patients should avoid these activities for several months at the very least. Certain foods such as nuts, fish, and their by-products should also be avoided. Slow heart rate symptoms can be treated with a drug called atropine, injected directly into the veins. If patients feel faint when they stand up, they may be given a drug like phenylephrine.
Activated charcoal could be beneficial if administered shortly after ingestion before the onset of nausea and vomiting. Activated charcoal could stop more of the ciguatoxin from being absorbed in the gut. One potential risk here is that if vomiting starts after the charcoal administration, it might seep into the lungs and cause inflammation.
Relying on mannitol, a type of diuretic administered via intravenous infusion, is a point of contention. In theory, mannitol could reduce swelling of the brain cells and abnormal electrical activity in neurons. But even though some people report that this treatment can lessen nerve-related symptoms or prevent them from starting, a double-blind trial showed that mannitol didn’t have any additional benefits for patients dealing with ciguatera toxicity, compared to simple saline solution. Still, some doctors recommend it, believing the potential benefits of mannitol to outweigh any negatives, so it should be considered for treating severe cases of ciguatera poisoning.
What else can Ciguatera Toxicity (Foodborn Illness Caused by Eating Fish Contaminated with Ciguatoxin) be?
Identifying ciguatera poisoning is often challenging. This is because its symptoms are not unique, it is relatively uncommon in areas away from the coast, many doctors are not aware of this illness, and there are no specific tests to diagnose ciguatera poisoning.
However, there are other conditions with similar symptoms as ciguatera poisoning that doctors might consider. These include:
- Shellfish poisoning, which can cause memory loss, diarrhea, and nerve damage. This is also related to an increase in algae in water bodies.
- Scombroid poisoning, a type of food poisoning usually from eating spoiled fish
- Common stomach viruses
- Organophosphate toxicity, which is usually due to contact with certain pesticides
- Botulism, a rare but serious disease from a toxin often produced in contaminated food
- Multiple sclerosis, a condition that affects the brain and spinal cord
- Guillain-Barre syndrome, a rare disorder in which your body’s immune system attacks your nerves
- Gastroenteritis caused by other sources like Salmonella, E. coli, or a parasite called Entamoeba histolytica
Accurate diagnosis greatly relies on paying keen attention to the patient’s history of symptoms and the physical examination. Lab tests can also assist in eliminating other potential causes.
What to expect with Ciguatera Toxicity (Foodborn Illness Caused by Eating Fish Contaminated with Ciguatoxin)
Ciguatera toxicity, a type of food poisoning usually from fish, tends to get better on its own, with symptoms typically lasting for just a few days. However, in some cases, these symptoms can last for a considerably long time, sometimes even months to years. Scientists are still not sure what factors might make the illness drag on for longer.
Patients who experience ciguatera toxicity, are advised to avoid certain foods and drinks for at least 6 months after the poisoning. These include fish, caffeine, alcohol, and nuts as they might bring back the symptoms. It’s also worth noting that the death rate from ciguatera toxicity is very low, reported in only 1% of cases.
Possible Complications When Diagnosed with Ciguatera Toxicity (Foodborn Illness Caused by Eating Fish Contaminated with Ciguatoxin)
If ciguatera poisoning is not treated, it might cause dehydration, weakness, heart palpitations, sensitivity to different temperatures, and psychological issues, on top of the harm it may cause to specific organs. Some people might experience symptoms again months or even years after first being exposed to the toxin. Deaths from ciguatera poisoning are extremely rare, but there have been cases. Generally, though, people tend to recover well from this condition.
Preventing Ciguatera Toxicity (Foodborn Illness Caused by Eating Fish Contaminated with Ciguatoxin)
Before visiting areas where ciguatera, a form of food poisoning, is common, it’s crucial for individuals to know the following to avoid exposure to the toxin:
- They should be aware of marine toxins, as well as the foods that might harbor them.
- They should keep an eye open for public warnings related to toxic algal blooms.
- When preparing risk-prone fish for eating, they should remove the liver, skin, and scales where the ciguatoxin is typically concentrated.
- It’s important to note that the ciguatoxin remains toxic after cooking because the heat can’t destroy it.
- If they show any symptoms of being poisoned, medical help must be sought immediately to avoid any further complications.
- Foods and drinks that might trigger a recurrence should be avoided.
- Finally, they should engage with local health authorities and healthcare providers to raise awareness about ciguatera.
By adhering to these safety practices, individuals can lower their risk of ciguatera poisoning and participate in community programs that aim at maintaining food safety.
