Pseudomonas bacteria are a genus of bacteria which exist widely in the environment. They are gram negative, rod shaped, non spore forming, motile, flagellated aerobes. Pseudomonas aeruginosea, probably the most well know of all pseudomonas strains, is an opportunistic pathogen that has the capability of adapting to many niches. It can infect animals and humans alike and can cross the species barrier and for this reason it is considered a potentially zoonotic pathogen. This type of bacteria is immune to many types of bacteria because it has within it’s cell wall a mechanism known as an efflux pump which pumps antibiotics back out of the cell before they have had time to take effect. It is the second most common bacterial contaminant in hospitals and it is known to be paticularly malicious in burn units where it prevents the regeneration of healthy tissue. Bacteria of the pseudomonas family are grown on blood agar which turns from a blood red color to a marine blue/green hue. It also gives off a quite pleasant slightly minty smell.
One form of Pseudomonas pathogen causes a highly contageous disease in horses which is also highly infectious to humans. The disease in horses is know as glanders because it affects the glands in and around the throat and jaws of the horse. This disease was common when colonial forces shipped large quantities of horses to places like Africa, the Middle East and the Far East. Now, this disease is more rarer. The scientific name of this pathogen is Pseudomonas Mallei and it is registered as one of the possible bacterial strains that could be used in bacterial warefare together with Clostridium Botolinum and Anthrax.
Other forms of Pseudonas bacteria are known to cause spoilage in food at low temperatures. These psicrophilic Pseudomonas strains include: P. fragi which causes spoilage of dairy products , P. taetrolens which causes mustiness in eggs and P. mudicolens, and P. lundensis, which causes spoilage of milk, cheese, meat, and fish.
The term spoilage is used in food hygiene for a condition by which the food takes on an unpleasant texture, color change smell taste. This does not mean that the food has necessarily become a serious health risk in the same way as if meat were infected with e.coli or salmonella, for instance, but at the same time it is definitely not advisable to eat spoiled food. It means that the food has been infected with bacteria which cause the physical nature of the food to change. For instance, meat may become slimy to the feel or the outer lawyer of certain foods may become pulpy, it may also smell slightly sour and change color. This happens to food which has been stored in refrigerated conditions for long periods of time in places which have not been properly cleaned with anti bacterial disinfectants. I often see this condition in places such as deli counters where meat is sliced in front of the customer.
However a little slime on meat, such as with cured pastrami in particular and with other types of processed meats is not always a sign of spoilage. It may well be due to a reaction between the protein of the meat, the curing chemicals and the air. Many manufacturers now use preservatives to prevent such spoilage. In addition, the reaction of the preservative with the air and other factors within the meat can cause the color of the product to change slightly as well. The color of the may become slightly irridescent or take on a greenish hue. If the meat smells even the slightest bit sour, feels or looks slimy or has a bad color refuse to accept it.
Spoiled food such as cured meats meat can cause stomach discomfort, diarrhea, vomiting or mild allergic symptoms in some people and may even become more serious in people whose immune system is compromised. Remember this central rule of food hygiene, “When in doubt throw it out”.
Fish products are particularly susceptible to spoilage and it can be very difficult to guess from a casual inspection if the deterioration of the fish is due to spoilage bacteria such as the psicrophilic pseudonmonas species stated above or if the cause is due to more dangerous, pathogenic forms of bacteria. If fish looks even slightly slimy, discolored or smells in the least sour don’t buy it or if it has turned bad in your fridge throw it out and clean you fridge thoroughly with disinfectant. (A tactic used by many fresh fish mungers to hide the tell tale smell of fish which has started to show signs of going off is to constantly pour sea water over it. Watch out for this trick. If you are not sure if you are smelling the actual fish or sea water, don’t buy the fish). Most importantly, keep all fish products in closed containers to avoid cross contamination with of by other food products in your fridge.
The same goes for eggs milk and cheese, if you distinguish any changes in color texture or smell, don’t take any risks, better to throw out and buy fresh. To lower the risk being sold spoiled or food which is about to spoil, buy only from supermarkets and stores which are very busy and have a high turnover of merchandise, particularly in the deli sections. Don’t be embarrassed to inspect what you buy, you are paying for fresh and healthy food and the decision to take what is on offer or not is entirely your own. The customer is always right. If you notice that the food you buy goes off quickly and you know that a). your fridge is clean and b). the temperature of the fridge is as it should be then take the food back to the store with your receipt and demand a refund or a fresh replacement. If the problem continues report your findings to your local authority for food hygiene.
What is listeriosis?
Listeriosis is a bacterial infection caused by the bacterium Listeria monocytogenes. Until several years ago it was thought that this bacteria only infected animals but it is now accepted that humans are also at risk from this disease. While many bacteria are generally seen to infect specific locations within the human body, Listeria may infect many different locations, such as the brain or the spinal cord membranes or the bloodstream.
L. monocytogenes is a gram positive, non-spore forming, motile, facultatively anaerobic, rod shaped bacterium. It is catalase positive, oxidase negative, and expresses a Beta hemolysin which causes destruction of red blood cells. This bacterium exhibits characteristic tumbling motility when viewed with light microscopy.  Although L. monocytogenes is actively motile by means of peritrichous flagella at room temperature (20-25C), the organism does not synthesize flagella at body temperatures (37C). 
Who gets listeriosis?
Anyone can get this disease, but those at highest risk for serious illness from this bacterium are newborns, the elderly, people with weakened immune systems, and pregnant women. Healthy adults and children occasionally get infected with Listeria, but they rarely become seriously ill. Listeria Monocytogenes is classified as an intracellular paracite. This means that it invades and lives within cells of the body thereby managing to evade the body’s immune system. Infection by as few as 1000 individual bacteria is considered enough for the disease to take hold. When listeric meningitis occurs, the overall mortality may reach 70%; from septicemia 50%, from perinatal/neonatal infections greater than 80%. In infections during pregnancy, the mother usually survives.
When do Listeria infections occur?
Infections occur throughout the year. Although most cases occur sporadically, food-borne outbreaks of this disease do frequently occur. Poor food hygiene and poor personal hygiene conditions are responsible for many of the recently recorded outbrakes.
How is listeriosis spread?
Listeria bacteria are widely distributed in nature and can be found both in water and soil. Infected animals may also serve as sources of contamination. Unlike other organisms, Listeria can be spread through several different methods. Ingestion or food-borne transmission of the organism, such as through the ingestion of unpasteurized milk or by the eating of contaminated vegetables, is often a source of many cases. In newborn infections, the organism can be transmitted from mother to fetus in utero, or directly to the fetus at the time of birth through the contact of the fetus’ blood supply with that of the mothers. Direct contact with the organism can cause lesions on the skin.
What are the symptoms of listeriosis?
Because listeriosis can affect many different parts of the body, the symptoms vary. For meningoencephalitis, the onset can be sudden with fever, intense headache, nausea, vomiting and signs of meningeal irritation. In other body locations, various types of lesions at the site of infection are the primary symptom. In most cases, Listeria infection causes fever and influenza-like symptoms resembling a host of other illnesses.
How soon after exposure do symptoms of listeriosis appear?
Listeriosis has an extremely variable incubation period. It can range from 3 to seventy days, but symptoms usually will typically appear within a month of infection.
How is listeriosis diagnosed?
Specific laboratory tests are the only way to effectively identify this disease. Since many cases may be mild, the disease may be much more common than is realized.
Are there any unusual features of listeriosis?
Listeria infections are a significant risk for pregnant women, who may not experience obvious symptoms. Infection of the fetus can occur before delivery and can cause abortion as early as the second month of pregnancy, but more often in the fifth and six months. An infection later in pregnancy may cause exposure during birth, sometimes resulting in infection of the newborn child which may be fatal.
Does past infection with Listeria make a person immune?
Past infection does not appear to produce immunity.
What is the treatment for Listeria infection?
Several antibiotics are effective against this organism. Ampicillin, either on it’s own or in combination with other types of antibiotics, is frequently used.
What can be done to prevent the spread of Listeriosis?
Since the organism is widly distributed throughout nature, basic sanitary measures such as only using pasteurized dairy products, by only eating cooked meats and washing hands thoroughly prior to the preparation of foods offer the best protection against infection by this disease.
In addition, the following recommendations are for persons who are categorized to be at high risk of infection, such as pregnant women, the elderly and persons with compromised immune systems:
Do not eat hot dogs, luncheon meats, or deli meats, unless they are reheated until they are steaming hot.
Avoid getting the liquid from hot dog packages onto other foods sources, utensils, and food preparation surfaces, and remember to wash hands after handling hot dogs, luncheon meats, and deli meats.
Do not eat soft cheese products such as feta, Brie, and Camembert, blue-veined cheeses, or Mexican-style cheeses such as queso blanco, queso fresco, and Panela, unless they clearly state they are made from pasteurized milk written on the labelling of the product.
Do not eat chilled pâtés or meat spreads. Canned or shelf-stable pâtés and meat spreads can be eaten.
Do not eat refrigerated smoked seafood, unless it is contained in a cooked dish, such as a casserole. Refrigerated smoked seafood, such as salmon, trout, whitefish, cod, tuna or mackerel, is most often labeled as “nova-style,” “lox,” “kippered,” “smoked,” or “jerky.” The fish is found in the refrigerator section or sold over deli counters of grocery stores and delicatessens and supermarkets. Canned or shelf-stable smoked seafood may be eaten.
Last Monday morning I received a phone call from the area superintendent of the department of public health. She told me that there was a steady stream of people falling sick due to eating food prepared by one of the large kitchens in our area. She continued to tell me that her department had been through the place with a fine tooth comb but still couldn’t find the source of the contamination. I arranged to meet them at the premises in question the following day to conduct an inspection.
To tell you the truth, I had a pretty good idea what I would be looking for because I had been to that particular kitchen several times in the past and had spotted a few things that seemed problematic. However, I had to make it seem as if I was earning my money so I decided that we would start somewhere quite far from the place that I suspected to be the problem.
We started by taking swabs of everything we saw and asked staff to provide swabs, blood, urine and stool samples. We checked the toilets of staff and diners alike and took swabs from all manner of cooking pots and trays,
I knew that this kitchen was using a type of bread basket within which to thaw meats and fish. The bread baskets were stacked one upon the other and left inside the two degree Celsius anti room of the freezer complex for up to four days. I also knew that the baskets were loaded onto a low level service trolley and brought up to the kitchen. I had known the chef of this kitchen for a number of years and I also knew that it was his practice to unload the baskets into plastic tubs after the lunch had gone out to the dining room. I always made a practice of doing this first thing in the morning before we started on the days chores.
What this meant was that the contents of the baskets were left to warm up from between seven o’clock in the morning until 11 o’clock in the morning. This wasn’t a very good practice. Every chef has his ways but I knew that this was not the exact point I wanted to look at closely. What bothered me were the baskets themselves. I had a word with the chef and asked him to make an exception today and vacate the baskets earlier. What i notices was what I suspected. After rinsing the basket with water to remove the blood I saw that there was a light colored plaque stuck to the plastic. I took a scraper and saw that it came away fairly easily. I took scrapings from all the baskets used that day and then took the baskets to the aluminium washing machine to see what happened.
The man working on the machine proudly took a stack of five baskets and but them onto the machine and presses the operating handle down. The baskets disappeared into the machine for a few seconds and then came out. The worker informed me that this was a very efficient way of washing the baskets. he then placed them back onto the service trolley which had not been washed only sprayed with a water gun and placed the baskets next to the lift ready to by taken back down to the freezers.
The guy in charge of the freezer units the proceeded to re fill them with produce for another day. I had noticed several things, 1) the baskets had not been scrubbed with a stiff plastic brush of Brillo pad with detergent, 2) they had only been rinsed inside the machine which used high pressure but was ineffective due to the fact that the stacking of baskets inside the machine rendered the high pressure ineffective,3) chicken, beef, pork and fish had been set out to thaw in the same tower of eight baskets.
All of this led us to believe that we had quite possibly found the missing link of the food contamination dilemma. What had been happening was that liquid released from the thawing meat and fish had been dripping onto the plaque in the bottom of the baskets which in turn had been dripping onto the neat inside the baskets below. Then we discovered something else. The worker who had been handling the baskets went to work on the dish washing machine that cleaned the crockery and cutlery merely wiping his hands on a towel and removing his plastic apron before going onto the dish washing machine. It was his job to remove the clean cutlery off the dish washing machine. We clearly saw that he could be contaminating the cutlery.
All we needed to do now was to take the cultures we had taken back to the lab and have them checked out. These were the findings. Camphilobacter, Staph Aureus, Salmonella, e. coli, vibrio an listeria were all present in large quantities within the plaque which we removed from the bread baskets. Our findings were relayed to the company management with the following recommendations. All bread baskets to receive immediate soaking in caustic soda. 2) All bread baskets to be scrubbed individually before putting them onto the aluminium machine,3) all bread baskets to be put into the aluminium machine individually and 4) all bread baskets to receive a weekly soaking in caustic soda. 4) aluminium machine worker was to thoroughly wash his hands and change overalls before helping out anywhere else.
A re check will be conducted in two weeks from the day all the baskets were washed in caustic soda.
When visiting China or any other country with a Chinese orientated culture it can be very challenging to try some of the exotic culinary preparations on offer. People of Chinese origin eat just about anything that is a source of protein. Local delicacies may include insects, reptiles, amphibians, all types of seafood and shellfish, many types of mamals and just about anything else you can think of.
Food poisoning among adventurous western tourists is quite common simply because of the fact that they have no or little awareness of the things which a local can stomach but would be very problematic for them. The prospect of being able to come home and show family and friends pictures of yourself munching on freshly fried cockroaches may be appealing but it may also turn out to be a mistake you might regret for a very long time.
Locals may have a much higher resistance to various food toxins and allergens that you. Their immune systems may well recognize and destroy bacteria which would make you very sick. Remember, they have been exposed to these things all their lives whereas for you it is completely new.
Many good hotels will keep lists of hotels which they feel that it is safe for tourists to eat and in addition they may also have a residential general practitioner on duty or be able to call a reputable GP within a very short space of time.
A good rule of thumb when eating in Chinese restaurants is only to eat in respectable busy places. Only accept your food it it is sizzling hot and do not order anything which your stomach is not used to. Also, never accept fruit which has been peeled for you, always opt to peel it yourself. Never eat salads. In fact, there are no salads in Chinese cuisine. Is it a coincidence that they all eat their food piping hot? Food for thought!
If you do fall sick in China or South East Asia always go to a doctor who has been recommended to you by a respectable establishment. Street doctors are often not qualified by internationally recognized medical schools and may make bad mistakes in diagnosis. Also some doctors may recommend unnecessary treatment and prescribe drugs that you do not need and which may do you more harm than good. It is also most unadvised to go to traditional practitioners because many of the herbal remedies which they prescribe may be infected with mold and cause more harm than good.
Common sense is an absolute must when eating of receiving medical treatment in China. The Chinese government itself are now organizing themselves to bring in a national standards authority which will act upon identical lines to those practiced in Eu regulations and the American FDA. The Chinese government has fully accepted that to continue to operate as they have until now is contrary to the Chinese national interest and prosperity of the Chinese nation. Please, be careful what you eat in China.
Scombroid fish poisoning is a toxic reaction caused by the decaying flesh of fish of the scombroid family. Fish of this family include bonito, tuna, sardines, anchovies, mahi,mahi, mackerel, king butterfly fish and kahawai.
All of these fish have dark flesh. Other types of fish may also be responsible for this reaction as well as the above mentioned. Scombroid fish contain a chemical substance called histadine within the meat. If the flesh of the fish reaches temperatures of above fifteen degrees celsius after being caught bacteria that are present in the skin of the fish convert the histadine in to scrombrotoxin. Market stalls are particularly susceptible to this through improper or no cooling facilities The primary component of scombrotoxin is another substance called histamine which causes the toxic reaction known as scombroid fish poisoning.
All forms of cooking have little or no effect in reducing the levels of histamine within an affected piece of fish even if all the bacteria that caused the histamine to be produced have been destroyed. Scombroid fish poisoning varies to other forms of fish poisoning in that the areas of flesh that were most decomposed will contain the highest levels of histamine and therefore only the people who eat from that particular area of flesh will feel ill. Others eating flesh from different areas of the same fish will feel no ill effect whatsoever.
Scombroid fish poisoning is not infectious and it is not an allergic reaction either. The person who was affected by this form of poisoning will have no ill effect from eating this type of fish or fish of the same family on future occasions provided it is caught fresh and stored in proper refrigerated conditions.
Symptoms will start to be felt in thirty minutes to one hour after eating the poisoned fish. Primary symptoms include warm flushes followed by the development of a profuse bright red rash starting on the neck or lower jaw and spreading to the lower abdominal area including the back. The rash is hot and itchy but unlike rashes in allergic reactions there is no swelling of the skin. Other symptoms may include any number or all of the following: a burning feeling in the mouth, a pounding headache, nausea, raised heart beat, dizziness, collapse caused by the lowering of the blood pressure, abdominal pain and diarrhea.
Symptoms may persist for a number of hours after which they will normally subside. In some cases, particularly in children and the elderly symptoms may take longer to disappear.
Prevention of this disorder lies solely in the correct handling of fish. All fish should either be cooked promptly after being caught or refrigerated at a constant temperature at four degrees Celsius until used. Removal of the skin also helps to prevent formation of the toxin by reducing the number of bacteria around the flesh of the fish.
Treatment of this condition is usually quite simple. Oral anti histamine is usually enough to eleviate the symptoms. Expert medical advise should be saught and the patient should receive a full medical exam in an emergency unit to eliminate any complications.
Zoonotic diseases are ones which are passed from the animal kingdom to human beings. Many micro organisms tend to be species specific and it is for this reason that there are not a great many zoonotic diseases. Some diseases passed on to us via animals are very common whereas some others are very rare. Some have the potential to cause world catastrophes whereas others may just about give us an upset stomach.
Below you will find a list of zoonotic diseases in alphabetical order.
Anthrax is a serious disease that is found in all warm blooded animals. The specific host is thought to be antelope and carnivores seem to react more slowly to the bacteria. The bacteria responsible for the cause of anthrax is Bacillus Anthracis. Human infections usually occur through the skin but it may also be inhaled or ingested. This is a very resistant spore forming bacteria whose spores may survive for decades in soil or animal products. The distribution is worldwide. Gastrointestinal anthrax is a very uncommon, often-fatal manifestation of the disease, caused by devouring meat from an animal that died of the disease. Gastrointestinal anthrax causes inflammation of the stomach and the intestine accompanied by sores or ulcers, much the same as the lesions that appear on the skin in the skin form of anthrax. The primary signs of the disease include nausea, vomiting, loss of appetite and fever, followed by severe abdominal pain, vomiting of blood, and severe and bloody diarrhea.
Brucellosis comes in four strains, B. abortus (in cattle), B. melitensis (sheep or goats), B. suis (pigs), and canis (dogs). The distribution of brucellosis is distributed worldwide. The disease id contracted via direct contact with animal excretions including milk. it is a disease caused by any of several forms of the gram-negative coccobacilli Brucella: Brucella melitensis, B. abortus, B. suis, and B. canis, the latter of which is very rare and causes only mild illness. Brucellosis is most common in rural areas among farming populations, vets, meat packers, slaughterhouse staff, and livestock breeders. Laboratory workers are also among those who are at risk. It is primarily a disease of animals (including cattle, pigs, sheep, camels, goats, and dogs); humans usually contract it through ingestion of contaminated and unpasteurized milk or other non cooked milk products or by ingesting raw meat or bone marrow, through skin lesions and cuts, through direct contact with an infected animal, or through the inhalation of dust particles that may be present in contaminated soil. Symptoms of brucellosis are manifested as follows: fever, chills, sweating, malaise, and weakness. The fever often occurs in recurring waves, rising in the evening and subsiding during the day, separated by periods of remission at intervals. Other symptoms may include weight loss, headache, muscle and joint pain, and an enlarged spleen, and often orchiepididymitis in young men. In some victims the disease is acute; however, more often it is chronic, recurring over a period of months or years. Although brucellosis itself is rarely fatal, treatment is important because serious complications such as pneumonia, endocarditis, meningitis, and encephalitis may develop. Tetracycline plus streptomycin is the preferred treatment for this disease; bed rest is also of great importance. A vaccine is available outside the United States. The disease can also be called Cyprus fever, dust fever, Gibraltar fever, Malta fever, Mediterranean fever and undulant fever. See also abortus fever.
Campylobacteriosis is caused by the bacterium campylobacter spp. It is carried by many animal species with a seemingly increasing incidence rate. Most species of animals seem to be reasonably host specific but cross infection is possible usually via fecal contamination of food. Improper or incomplete cooking of food is the most common way that the disease is spread, and it is commonly thought by bacteriologists that poultry account for over half the diagnosed cases. Untreated water and raw milk are also potential sources of contamination.
The incubation period after exposure is from one to ten days. symptoms begin with a day or two of mild fever, muscle aches, and headaches. This stage is followed by symptoms that involve the the intestinal tract. Diarrhea occurs with or without the presence of blood and severe abdominal cramps are the overriding intestinal symptom. The severity of symptoms may vary from case to case, ranging from only mild fever to severe dehydration and very rarely death (this is seen mainly in the very young or old). The disease usually lasts for about a week, but persists longer in about twenty percent of cases. At least ten percent will have a relapse, and some patients will continue to pass the bacteria for several weeks after recovery.
Clostridial disease is caused by the bacterium clostridium spp. It is transferred by mammals, birds and fish with a worldwide distribution. Although the disease is normally transmitted through wound infection, food poisoning does occur. There is little danger of cross species transmission. The clostridial family of bacteria are noted by their ability to manufacture very potent toxins. The most potent toxin in nature is produced by the bacterium Clostridium botulinum. This toxin renders the bodies ability to contract muscles ineffective and death will occur by paralysis and asphyxiation, or the inability to inhale. Clostridium botulinum is found in the manure of animals along with clostridium tetani, clostridium difficile and clostridium perfringens, which causes gas gangrene. These bacteria are spore forming and the spores can survive for many years in soil. When conditions are favorable the bacterial spores will grow back into bacteria and begin to produce toxin.
Food that has been improperly preserved or stored can harbor botulinum toxin-producing clostridia. Botulism symptoms usually appear within 18-36 hours after eating contaminated food, in extreme cases it may take four hours to eight days for the bacteria to develop toxin. Initial signs of infection include blurred or double vision and difficulty in swallowing food and speaking. Gastrointestinal problems may include constipation, nausea, and vomiting. As botulism progresses, the victim experiences weakness or paralysis, starting with the head muscles and progressing down the body. Breathing eventually becomes increasingly more and more difficult. and without medical intervention, respiratory failure and death are the likely outcome.
Listeriosis is caused by the bacterium listeria monocytogenes and it can be found in numerous species of animals and birds. It has a worldwide distribution. Listeriosis was traditionally considered to be a disease of animals for the most part. However in recent decades there has been an alarming increase in the incidence of this disease. The symptoms can be severe and patients who are high risk may have a problem overcoming listeriosis. It is becoming resistant to many forms of antibiotics. This is primarily a food borne bacteria. Listeria can be contracted by the ingestion of contaminated meat, dairy products, shellfish, dust and by coming into contact with infected animals. Listeria can pass through the wall of the gut and enter the bloodstream. It likes to sit on the central nervous system and spinal column. Pregnant mothers can spread this disease to their unborn babies through the placenta. Listeria cam cause severe flu like symptoms, meningitis and encephalitis. Listeria is also found in soil, sewage and in five percent of the intestines of humans without them feeling any ill effect.
Salmonellosis is transmitted by the salmonella spp. Bacteria which has over two thousand serotypes. It can be found in all animal species but it is not commonly thought to infect fish. The distribution of salmonellosis is worldwide and the occurrence of this disease is mostly attributed to the ingestion of undercooked food which is contaminated with feces. It is a form of gastroenteritis that is usually caused by the ingestion of food that has been contaminated with a species of Salmonella bacillus. It is characterized by an incubation period of six hours to forty eight hours which is followed by sudden colicky abdominal pain, high fever, and bloody, watery diarrhea. Nausea and vomiting are common symptoms, and abdominal signs may be almost identical those of acute appendicitis or cholecystitis.
Symptoms usually last from four to seven days, but diarrhea and fever may persist for up to 2 weeks. Dehydration may occur. There is no specific treatment for salmonellosis. Antibiotics are usually not prescribed unless the disease has spread beyond the intestine and into other organs. Adequate cooking, good refrigeration, and attention to personal hygiene, especially the washing of hands may reduce the frequency of salmonella outbreaks. Salmonella can also cause typhoid fever.
Tuberculosis is caused by the bacterium mycobacterium bovis (cattle). It can be transferred to humans via cattle and non human primates. The distribution of tuberculosis is worldwide and has now been linked to the aids virus. The disease can be transmitted by any animal species including humans. It now normally takes treatment with three forms of antibiotics simultaneously to combat this bacteria. No other disease throughout history has claimed so many lives. The tuberculosis bacteria will infect the organ via which it entered the body. In most cases this is the lungs. As it has a protective enveloping it manages to outsmart the bodies specific immune system. The tuberculosis bacteria can survive within the non specific white blood cells and by colonising them it can move around the body from organ to organ. This is a slow process. It can transpire over a period of years. In the early part of the last century one in seven people were infected with tuberculosis. In the western world this number has dropped greatly due to the improvement in living conditions and lifestyle. In the third world, particularly Africa , conditions are still right for tuberculosis infection.
Tularemia is transmitted by the Francisella Bacteria. It is transmitted to humans by rabbits, dogs, cats, rodents, sheep and deer. Its distribution is circumpolar within the confines of the northern hemisphere. The disease is transmitted through ingestion when exposed to infected animals and also via bites of arthropods. It is an infectious disease of animals caused by the bacillus Francisella (Pasteurella) tularensis, which may be transmitted by insect vectors or direct contact. It is characterized in humans by fever, headache, and an ulcerated skin lesion with localized lymph node enlargement or by eye infection, GI ulcerations, or pneumonia, depending on the site of entry and the response of the host. This disease can be fatal if not treated with the appropriate antibiotics. Treatment includes streptomycin, chloramphenicol, and tetracycline. Recovery produces lifelong immunity. A vaccine was used in the past to protect laboratory workers but is not currently available; however, a new vaccine is in development. Also called deerfly fever, rabbit fever. Also spelled tularaemia.
Vibriosis is transmitted by the Vibrio parahaemolyticus or the V. alginolyticus bacteria. It is transmitted salt water fish and shellfish and is found primarily in the pacific regions including Asia, Australia, North America and the gulf of Mexico . The cause is the ingestion of undercooked contaminated food. Vibriosis is caused by eating seafood contaminated with Vibrio parahaemolyticus or Vibrio vulnificus. These bacteria damage the inner wall of the intestine, which causes diarrhea and related symptoms. Vibrio vulnificus can get through the intestinal wall and into the bloodstream.
Persons at risk for severe, often fatal vibriosis include those with liver disease (cirrhosis), excess iron (hemochromatosis), thalassemia (a blood disorder), AIDS, diabetes, or those who are immunosuppressed.
Symptoms of intestinal infection occur within two days of eating contaminated seafood. Symptoms last for two to 10 days and include watery diarrhea, abdominal cramps, nausea, vomiting, headache, and possibly fever. Symptoms of a blood infection develop one to two days after eating contaminated seafood, and include fever, chills, low blood pressure, and large fluid-filled blisters on the arms or legs. Similar blisters can also be produced by a Vibrio vulnificus skin infection. This can occur when the skin is pierced by the spines of infected fish. These infections can be severe and sometimes require amputations if not treated in time.
Yersiniosis is caused by the yersinia paratuberculosis or the V enterocolitica bacteria and is passed onto human beings by Animals and birds. It is distributed in the northern hemisphere and is transmitted via contaminated food and water.
Yersinia p. causes septicemia (blood poisoning) often with signs of gastroenteritis which is caused by Yersinia pseudotuberculosis, this occurs in wild rodents, birds, and most domestic species, particularly cats, although this is not common. The symptoms are: high fever, severe toxemia with a high fatality rate. At postmortem there are large numbers of embolic abscesses in most of the internal organs. It is also called pseudotuberculosis because of the way it infects multiple organs.
Occurs also in many species of fish as a septicemia. This form of infection is caused by Yersinia ruckeri.
In my previous article on shellfish and crustaceans I referred to instances of when seafood became contaminated once it was out of the sea. There are many forms of seafood poisoning and I would like to talk of one of the more problematic and undetectable forms of seafood poisoning that we encounter quite often.
In the field of food hygiene we must also look at the condition of food which has been caught in the wild. This includes the world’s fisheries industry. Wild sea food, particularly that which has been caught on or around coral reefs, is thought to be superior to sources which are grown by aquaculture technologies. Locus, red snapper, lobster and shrimp caught and served fresh from the coral reef are prized as delicacies.
All creatures that live on the coral reef are part of a food chain. Everybody is eaten by somebody else eventually. The food chain begins with single cell creatures such as plankton. Some forms of plankton emit a toxin called “ciguatoxin”. The reaction to this toxin in humans is called “ciguatera”. (sig-ua-terra).
The plankton enters the food chain at the bottom end where it is eaten my small coral reef creatures. The small creatures are eaten by bigger ones until, finally we arrive at the sea creatures that we love to sea on our plates at the seafood restaurant.
It is important to stress that although the toxin is released into the flesh of the fish it has little or no effect upon them and they can continue to live out there lives and function quite well despite being infected by the toxin. The toxin tends to accumulate mostly in the liver, pancreas, gills and head but is also present in potentially problematic concentrations throughout the muscle tissue as well.
Cases of ciguatera are seen mostly where raw seafood flesh is served but it is important to stress that the toxin is not destroyed or neutralized by the cooking process nor is it destroyed by the powerful acid (HCl) which is present in our stomachs during the digestive process.
The reaction experienced by victims of ciguatera include all or most of the classic allergic reaction symptoms. Sufferers may experience sweating, dizziness, nausea, fainting, tightness of breath, burning of the mouth, itchiness, rashes, blurring of the vision and other symptoms.
This may sound frightening but although highly unpleasant, Ciguatera is very rarely fatal, especially if the victim arrives promptly to a place where he or she can receive modern medical treatment. Patients usually make a full recover within three to five days.
Some cases can be fatal but these cases are usually where people have severe medical conditions or other sensitivities that can be sparked off in conjunction with the symptoms of Ciguatera.
The only way to protect yourself is never to eat seafood in restaurants in locations that you have no prior knowledge of. Prefer to eat fish species from the open sea or freshwater sources. Eat or buy seafood from reputable businesses that have no previously reported incidences of Ciguatera.
If you are like me you like shellfish in all forms, shapes and sizes. I just cant get enough shellfish, particularly shrimps, squid and lobster. Personally, I think that shellfish are one of the best food sources available. They are almost all protein, no fat and almost zero cholesterol. What could be better?
But wait. Before you let yourself dash off to the nearest seafood restaurant here are a few things that you should know about your favourite tasty morsel. Shellfish are one of the most dangerous of all forms of food. That’s right, you heard me well, one of the most dangerous and for several reasons.
Firstly, even if you are one hundred percent sure that the shellfish in question is completely fresh, there is still the question of seafood allergies to consider. Shellfish have one of the highest counts of allergic reaction rates per capita. The reason for this is precisely because shellfish are constituted primarily of protein. Most of our immune responce reacts to proteins and the reason for that is because our antibodies are themselves proteins and they are designed to seek out foreign invaders who’s skeletal walls are made of protein.
One of our antibodies, which is known as “I.G.E” causes very acute responses of the immune system. One such immune response is anafilactic shock. If a protein from a shellfish is recognized as an alien threat and becomes attached to I.G.E. antibodies, a potentially fatal chain of reactions may be set into effect.
So, say a person would like to try shellfish for the first time, how could he test if he has an allergic response? One simple option is to take a piece of the shellfish after it has been cooked and to rub it onto the inside of the lower lip. If you are allergic the lip will either swell up, tingle or produce a burning sensation. One may also feel internal side effects such as tightness of breath, facial swelling, excessive salivation,sweating and drop in blood pressure which may cause vomiting , dizziness or red rashes over extensive areas of the body. If that is the case, seek medical treatment immediately in a hospital and don’t go anywhere near shellfish, they are not for you.
Up to now I have talked about allergic reaction to the protein in fresh and untainted shellfish. There is, however a different kind of allergic reaction that one can get from shellfish. It may be of little consequence to the sufferer how he got his allergic reaction but the difference is important from medicinal and scientific perspectives. One may suffer an allergic reaction to bacterial toxins and/or to waste products of bacteria within the shellfish itself. This is important because the person affected from such bacterial substances may not be allergic to shellfish at all per say and had it not been for the bacterial activity, no reaction would have been encountered at all.
The other danger concerning shellfish is that of bacterial infection. Shellfish are a very easy target for bacteria because a) they contain a high percentage of water and b) they are made up of protein which are an excellent source of food for many dangerous forms of bacteria such as the clostridium genus. Shellfish become contaminated up to ten times more quickly than most other forms of food.
This means that we need to take great care when dealing with shellfish. Shellfish are safest when bought frozen. The reason for this is they are caught by trawler ships which are really floating factories and they are frozen and packed within minutes of being caught on production lines which are maintained at a constant ambient temperature of four degrees celcius. In conditions such as these the likelihood of contamination is as near to zero as it is possible to get.
So how do you prepare frozen shellfish? My advise is not to thaw frozen shellfish. Boil water and throw them into the boiling water. Cook them until your crustaceans have changed color and all of them have turned pinky orange in color. Take them out of the water without cooling them at all and after allowing them to drain mix instantly with your pre cooked sauce, while the sauce is still boiling. Serve sizzling hot.
Never allow shellfish dishes to cool and I strongly advise against re heating shellfish dishes, including Paella. Keep it simple and safe, thats the key. In the case of frozen clams, mussels, winkels and such like, discard any that have not opened during the cooking process.
When buying fresh shellfish you should always ensure that the creatures are still alive. If they don’t move, don’t buy. Shells like clams should be closed and you should see them tighten the pressure of the closure when you tap the shell. Do not buy any that don’t react. Personally I like to buy directly from the fishing boats right after they have docked. That way I am one hundred percent sure that they are absolutely fresh. Definitely do not by anything that is not stocked in crushed ice.
One trick that a lot of merchants use and you should look out for is to splash fresh sea water over shellfish and other forms of fish. The reason they do this is so that the merchandise had a fresh sea smell that will make it more difficult for you to recognize other bad smells that might be present on fish and shellfish that has not been stored properly and has been outside for an extended period of time. Watch out for this. If you sea a bucket of water near a stand, you will now know it’s purpose.
Shellfish should be cooked in a sauce which is tart, peppered and salted to taste. All of these qualities will lower the Ph of the shellfish and lessen the risk of bacterial growth. Avoid adding leaf herbs to shellfish because leaf herbs have bacteria on them which may contaminate your food.
All spices and herbs, if used, should be fried in oil at the beginning of the preparation of the sauce. This way, any bacteria in the spice or on the herb will be killed by the heat of the oil.
Follow these basic principles and you should stay out of shellfish hell.