Wild Game And Fish And How To Consume Them Safely, Part 1

General Health, Infectious Diseases, Environmental Health, Healthy Living
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Many people significantly underestimate the risks associated with consuming meat from wild animals. First of all, this is due to a persistent belief in everything “natural” and the conviction that game meat is a priori cleaner and healthier than store-bought meat. This misconception is further reinforced by the habits of hunters and tourists: “we have always cooked it this way,” “hot food cannot be raw,” “it is natural meat.” As a result, people become convinced that game is safe in itself, regardless of how thoroughly it is prepared.

However, wild animals live in natural ecosystems saturated with parasites, bacteria, and various vectors of infection. Unlike farm-raised animals, game does not undergo veterinary control, does not receive preventive antiparasitic treatments, and regularly comes into contact with an environment in which pathogens are not the exception but the norm. Therefore, meat from wild animals initially has a completely different biological profile, and the risk of human infection directly depends on how exactly this meat was prepared, on what surface it was processed, and where it was stored.

In this article, we examine infectious problems characteristic of North America-primarily Canada and the United States, but also Mexico and countries of the Caribbean region, including Cuba. The main focus remains on those types of game most commonly consumed by residents of northern regions and hunters: bear, wild boar, deer, moose, caribou, as well as freshwater and marine fish. The purpose of this article is to explain which infections are transmitted through the meat of wild animals, which symptoms should raise concern, and what measures need to be taken to prevent severe consequences of these infectious problems.

How infections are transmitted through the meat of wild animals

The risk of infection is not related to the quality or freshness of the meat, but to the biological characteristic of wild animals being natural reservoirs of parasites and bacteria. Microorganisms are present in muscles, internal organs, blood, and intestines, do not change the color, smell, or taste of the meat, and remain viable with incomplete heat treatment. Freezing also does not guarantee decontamination, including cases involving resistant northern strains of Trichinella, Sarcocystis, and fish parasites.

Main routes of infection transmission

Infection occurs through a combination of foodborne and contact mechanisms. Infection can enter the body through the following routes:

  • Consumption of undercooked or partially raw meat, especially large or dense pieces;
  • Contact with blood and internal organs of the animal during carcass processing, especially in the presence of micro-injuries to the skin;
  • Cross-contamination of hands, knives, clothing, and any surfaces that have come into contact with raw game;
  • Use of the same tools for raw products and for already prepared food;
  • Inhalation of aerosols (vapors) during opening of the abdominal cavity, which is important for pathogens transmitted through tissues and biological fluids;
  • Consumption of poorly smoked, cured, or cold-prepared meat;
  • Consumption of liver and other organs of wild animals without complete heating;
  • Consumption of raw or lightly salted fish in which parasites are preserved.

Insufficient heat treatment as a key factor

The main mechanism of foodborne infection is related to the fact that the internal part of the meat does not reach the temperature required to destroy infectious agents. The outer layer may appear cooked, while the deeper tissues remain insufficiently heated, especially in large and dense bone-in cuts.

This is typical for meat from bear, wild boar, moose, deer, and other animals with dense muscle structure and low intramuscular fat content, where heat transfer is slowed.

In field conditions, the risk increases: open flame quickly chars the surface, heat penetrates inward slowly, and the lack of temperature control does not allow an objective assessment of the degree of heating of the central layers of the meat.

Contact and technological mechanisms of infection

In addition to cooking, mechanisms of infection associated with direct contact with animal tissues and processing conditions play a significant role. In practice, risk is formed by a combination of factors rather than by a single isolated process.

Some pathogens are transmitted predominantly through meat consumption, others through both foodborne and contact routes, and some pose a danger only through interaction with fur, internal organs, or biological fluids, but not through consumption of properly prepared meat.

Resistance of pathogens to freezing and processing

An additional risk factor is the resistance of certain parasites and microorganisms to freezing and mild heat treatment. Trichinella nativa remains viable during prolonged freezing. Anisakis larvae survive unstable or insufficient freezing of fish. Sarcocystids are not destroyed by surface frying. Toxoplasma is eliminated only when a sufficient temperature is reached in the center of the cut. Home smoking and curing can create conditions for botulinum toxin formation.

Carcass processing as an independent route of infection

A significant proportion of infections is associated not with food preparation, but with the process of carcass processing. At this stage, a person comes into contact with blood, tissues, and internal organs, where pathogen concentrations may be particularly high. When the skin is damaged, pathogens can penetrate directly into the body.

Typical risks include:

  • Entry of biological material into open skin lesions;
  • Contact with skin without barrier protection;
  • Formation of splashes and fine aerosols during opening of the abdominal cavity;
  • Contact of contaminated material with mucous membranes;
  • Contamination of hands and tools with intestinal contents;
  • Use of the same knife for internal organs and for further meat processing;
  • Transfer of bacteria from raw meat to ready-to-eat products.

Thus, infection through the meat of wild animals is determined by a combination of factors: insufficient heat treatment, contact with tissues and biological fluids, cross-contamination, and resistance of pathogens to freezing. In the absence of temperature control, sanitary conditions, and proper tools, the risk persists even with a product that appears visually “well cooked.”

Which infections and toxins are transmitted through undercooked meat of wild animals and fish

The danger of undercooked game meat is primarily associated with parasitic infections. Unlike bacteria, which often die with minimal heat treatment, parasites remain viable deep within muscle tissue and become active when the meat remains pink inside. These infections progress differently: some cause acute pain, others prolonged weakness and metabolic disturbances, and others may affect muscles, the heart, or the nervous system.

Parasitic infections transmitted through insufficiently prepared meat of wild animals and fish

  • Trichinella - larvae are located in the muscle fibers of bear, wild boar, caribou, and marine mammals; after entering the body, they cause fever, pronounced muscle pain, eyelid edema, weakness, night sweats, and elevated CK levels (a marker of muscle damage); northern strains are resistant to freezing, i.e., they remain viable after the meat has been thawed;
  • Toxoplasma gondii - present in deer, moose, and wild boar; causes prolonged elevation of body temperature (approximately 37-37.8 °C), weakness, muscle pain, and enlarged lymph nodes; particularly dangerous for pregnant women and immunocompromised patients;
  • Sarcocystis - widespread among moose and deer; the intestinal form causes acute gastroenteritis within a few hours after eating; the muscular form develops later and manifests as weakness and muscle soreness;
  • Taenia - tapeworms found in wild boar and deer; cause chronic abdominal pain, bloating, and weight loss;
  • Anisakis - a parasite of marine fish, including wild salmon; provokes acute abdominal pain, vomiting, and allergic reactions;
  • Diphyllobothrium - a parasite of freshwater fish; leads to vitamin B12 deficiency, anemia, and chronic fatigue.

In addition to parasites, there is also a bacterial risk. Meat from bear, wild boar, and wild birds may contain Salmonella, Yersinia, and Campylobacter. If the meat is not fully cooked, some bacteria remain viable and cause acute diarrhea, vomiting, and fever. These infections are usually limited to the gastrointestinal tract but, in cases of dehydration and weakened immunity, can lead to more serious consequences.

Bacterial infections associated with insufficient heat treatment of game

  • Salmonella - causes acute gastroenteritis with diarrhea, vomiting, and fever;
  • Yersinia - accompanied by abdominal pain and diarrhea and may sometimes mimic appendicitis;
  • Campylobacter - leads to diarrhea, abdominal pain, and prolonged or recurrent elevation of body temperature (approximately 37-37.9 °C);
  • Brucella - can be transmitted through consumption of insufficiently prepared wild boar or deer meat, although infection more often occurs during carcass processing; causes undulating fever, night sweats, and persistent weakness.

Viruses should be mentioned separately, as they can also be transmitted through insufficiently prepared organs of wild animals, primarily the liver. Of greatest importance are viruses characterized by resistance to partial heat treatment.

Viral infections associated with consumption of undercooked game

  • Hepatitis E (genotypes 3 and 4) - detected in wild boar and deer; transmitted predominantly through insufficiently prepared liver; causes nausea, weakness, elevated liver enzymes, and can lead to pronounced hepatitis;
  • Orthohepevirus C (HEV-C) - found in rats and small mammals; rare cases of human infection are associated with consumption of poorly prepared tissues;
  • Aujeszky virus - dangerous for dogs and other animals but does not pose a threat to humans.

Toxic food poisonings associated with fish (non-infectious)

These conditions are not associated with parasites, bacteria, or viruses and do not depend on heat treatment. They are caused by toxins that accumulate in fish tissues and occur mainly in warm marine regions.

  • Ciguatera - occurs after consumption of reef fish (barracuda, grouper, snapper); causes acute gastrointestinal symptoms, tingling around the mouth, numbness, temperature inversion (when cold is perceived as hot), and neurological manifestations;
  • Scombroid (histamine poisoning) - associated with improper storage of fish (tuna, mackerel, mahi-mahi); causes skin flushing, headache, burning sensation in the mouth, urticaria, and gastrointestinal symptoms; heat treatment does not destroy the toxin.

Most of these infections cannot be diagnosed if the physician does not know that the person consumed game meat or had contact with it; therefore, knowledge of transmission routes is a key step in correct diagnosis and prevention of complications.

Infections that do not have a foodborne route of transmission and are associated with other mechanisms

It is important to clearly understand which pathogens are associated specifically with insufficient heat treatment and which are related to carcass processing, contact with blood, or the animal’s environment. This helps avoid false associations and prevents attributing infections to meat that in fact do not have a foodborne route. Such errors are common among hunters and even among medical professionals when a patient presents with symptoms but forgets to mention carcass processing or work in a contaminated environment.

  • Francisella tularensis (tularemia) - transmitted through contact with blood and tissues during carcass processing, via aerosols, bites of blood-sucking insects, or wound contamination; properly cooked meat is safe;
  • Echinococcus - infection occurs through ingestion of parasite eggs from contaminated fur or soil; eggs are located not in muscle tissue but in the intestines and on the surface of the fur; meat is not a source, and heat treatment completely eliminates the risk of transmission;
  • Leptospira - transmitted through water or surfaces contaminated with urine of infected animals; associated with proximity to bodies of water or carcass processing, but not with consumption of meat;
  • Clostridium botulinum (botulism) - produces toxin under anaerobic conditions during improper smoking or curing; fried or boiled game meat itself is not a source;
  • Borrelia burgdorferi (Lyme disease) - transmitted exclusively through tick bites; does not survive in muscle tissue and is not preserved in meat; foodborne transmission is completely excluded.
  • Rabies - not associated with meat consumption; transmitted through bites or saliva contacting damaged skin or mucous membranes; any such contact requires immediate medical evaluation and consideration of post-exposure prophylaxis.
  • Chronic Wasting Disease (CWD) - a prion disease in deer and moose; foodborne transmission to humans has not been confirmed, but risk exists through contact with brain and lymphoid tissue during carcass processing; use of gloves and avoidance of contact with brain structures significantly reduces risk.

It is important to understand which infections are transmitted through food and which occur through contact with the animal or the environment. Properly prepared meat protects against most parasites and bacteria but does not eliminate the risk of infection during carcass processing or handling of internal organs. For hunters and people preparing game in field conditions, this is particularly important.

How infection develops after consuming undercooked meat of wild animals. Symptoms, time course, and the “window of rescue”

Infections associated with consumption of undercooked meat of wild animals or fish develop in stages. Symptoms may appear hours, days, or weeks after eating. Understanding the timing of symptom onset helps seek care in time, choose appropriate investigations, and prevent severe complications.

In the early stages, manifestations often resemble ordinary food poisoning, which delays seeking medical attention.

The first hours - up to 24-72 hours. Early symptoms and the beginning of the “window of rescue”

At this stage, the pathogen most often remains in the intestines and has not yet spread to muscles or internal organs. This is the most favorable period, when early medical attention can significantly reduce the risk of severe disease and complications.

Symptoms in the first hours:

  • Diarrhea, nausea, and vomiting;
  • Acute abdominal pain;
  • Fever or prolonged elevation of body temperature (approximately 37-37.8 °C);
  • Sharp stomach pain, especially after fish;
  • Possible allergic reactions, including swelling, itching, urticaria, and rarely severe reactions.

Laboratory findings:

  • Blood tests often remain normal;
  • Normal results at this stage do not exclude infection.

2-7 days. Formation of a systemic response

During the first week, the body begins to respond systemically. Some parasites and bacteria may begin migrating into tissues. Symptoms become more persistent.

Symptoms at 2-7 days:

  • Ongoing diarrhea and signs of intoxication;
  • Marked fatigue and body aches;
  • Mild to moderate fever;
  • Enlarged lymph nodes;
  • Onset of muscle soreness.

Laboratory changes:

  • Initial eosinophilia;
  • Moderate elevation of CRP;
  • Possible early changes in certain enzymes.

Treatment at this stage remains highly effective and can completely change the prognosis.

1-6 weeks. Period of maximal symptoms and the most informative diagnostics

At this stage, the infection enters the tissue phase, and symptoms become most pronounced. This is the best period for diagnostic confirmation, as laboratory markers already clearly reflect active disease.

Symptoms at 1-6 weeks:

  • Fever and pronounced muscle pain;
  • Eyelid edema, night sweats, severe weakness;
  • Pain with eye movement;
  • Sleep disturbances;
  • Shortness of breath, chest pain, heart rhythm disturbances;
  • Persistent digestive disorders;
  • Increasing fatigue.

Laboratory markers:

  • Marked eosinophilia;
  • High IgE;
  • Elevated CK (muscle damage);
  • Elevated CRP;
  • Elevated urates;
  • With tapeworm infections - decreased vitamin B12 and anemia.

Why diagnosis is most accurate at this stage:

  • The immune response is fully developed;
  • The pathogen is located in tissues;
  • Tests reflect the active phase of the disease.

At this stage, it is possible to prevent:

  • Severe myositis;
  • Damage to the heart muscle;
  • Neurological complications;
  • Liver involvement.

After 6 weeks. Late stages and risk of chronic complications

Delayed presentation is associated with a high risk of prolonged disease course and incomplete recovery.

Late manifestations:

  • Persistent severe muscle pain and weakness;
  • Constant fatigue;
  • Anemia;
  • Metabolic disturbances;
  • Cardiac and neurological complications;
  • Very slow recovery.

Laboratory changes:

  • High eosinophilia;
  • Markedly elevated CK;
  • Decreased vitamin B12;
  • Elevated liver enzymes.

When waiting is not acceptable

Seek medical care as early as possible if the following appear after consuming game or fish:

  • Muscle pain and weakness;
  • Fever or night sweats;
  • Persistent digestive disturbances;
  • Eyelid swelling;
  • Shortness of breath or chest pain.

Symptoms appearing 1-4 weeks later are particularly dangerous, as some parasitic infections can affect the heart muscle and cause myocarditis and rhythm disturbances.

What must be communicated to the physician

When seeking care, it is important to state directly:

  • What exactly was eaten (type of game or fish);
  • How the meat was prepared;
  • Whether the meat was undercooked;
  • Whether you participated in carcass processing;
  • When the meal took place;
  • When the first symptoms appeared;
  • Explicitly state that you suspect a connection with game.

It is important to understand laboratory testing and diagnostics

In the early stages, test results may still be negative. In such cases, treatment decisions are made based on symptoms and history-this is called clinical diagnosis, and it is justified.

Where samples are sent in British Columbia (BC)

  • Initial evaluation usually begins through a family physician with routine blood and stool tests (for example, through LifeLabs);
  • If advanced diagnostics for rare or parasitic infections is required, samples are not tested in standard commercial laboratories but are sent through a physician to a reference laboratory;

Main reference laboratory in BC:

  • BC Centre for Disease Control (BCCDC Public Health Laboratory, Vancouver) - this is where physicians send samples for specialized parasitological and zoonotic diagnostics;

Important:

  • Patients do not send samples themselves;
  • Referrals are issued by a physician or infectious disease specialist;
  • If necessary, a physician may request consultation with an infectious disease specialist.

Referral of samples to a reference laboratory may be initiated not only by an MD (family physician or infectious disease specialist) but also by a licensed ND (naturopathic doctor). Both MDs and NDs in BC have the right to initiate laboratory investigations and send samples, following established procedures, to public health reference laboratories when there are justified clinical indications.

The most effective treatment is possible before test results become positive. If symptoms appeared after consuming game, do not wait, even if initial tests are “normal”.