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Diseases in Role Playing Games
Part 1: Bacterial Infections

Copyright D. Andrew Ferguson ©2001

Edited by Jamie Revell for The Guild Companion


The material provided in this article is intended for game use only and is not intended for self-diagnosis. The material is not guaranteed to be accurate and is not an appropriate substitute for the care of a licensed physician.

What will these articles attempt to accomplish?

This series of articles will attempt to provide information that is useful and easy to understand. Various kinds of infectious diseases will be discussed, other topics will include how and when to include diseases into your campaigns, what your players are likely to expect and the various factors that can affect the diseases.

What is a disease and why should you include it in your role playing games?

For the purposes of this article we will define the term disease as "any abnormal circumstance in which the body is unable to perform its normal functions." The normal functions are the regular everyday things such as breathing, eating, etc. There are many reasons why a GM would wish to include diseases in a campaign; perhaps it is a gritty campaign where the PCs are constantly surrounded by death. Perhaps one of the PCs is a Cleric or a physician who needs a little bit more attention paid to their character. Despite their occasionally odd settings most RPGs have at least some semblance of reality in them and the inclusion of diseases into the campaign can act as another link to reality if done correctly. If done incorrectly the players will become upset. Many players will not mind the inclusion of a wider variety of diseases in a game, but on the other hand your players are not going to want to lose their favourite characters to a heart attack in the middle of battle just because they consistently ate fatty foods. A balance must be found to allow the inclusion of a wider variety of diseases but still maintain that the diseases are only a small part of the adventure.

These articles will deal mostly with infectious diseases that could actually affect game play; sure a sneezing barbarian is cute, but any GM could easily wing it when he tries to move silently.

Different genres of RPGs will be affected differently by the inclusion of these diseases.

Most fantasy games already include a variety of diseases, although they are usually in the form of a spell that evil clerics can cast at unsuspecting PCs. There are usually very few of these diseases to choose from, and the descriptions given in the spell usually assume that the GM and players already have a basic understanding of the disease. This situation can be improved by including more diseases and having a better description of how the disease affects the afflicted individual. The grittier and more realistic a fantasy campaign is the more likely that diseases should play a small part, however if the game is more epic than it might not make sense to allow the heroic characters to catch a cold.

Many contemporary games could benefit from having more information on modern day diseases. This information could be used as regular diseases, as genetic engineering projects gone wrong, or as the basis of Bio-weapons.

Most people believe that the future will bring cures for many of the worst diseases that we now face. However as we travel to new places in the future we will find many new and wonderful things but we will also find new diseases. Sci-fi games can also benefit from including modern day diseases because many medical professionals will be baffled if a thought to have been destroyed disease comes back creating an epidemic in a population that has no immunity to it. Sci-fi games can also benefit from including genetically altered forms of real diseases; these altered up versions of normal diseases could have fantastic properties. Some futuristic diseases could even be caused by advanced technical means such as nanites, radiation, or alien spores.

One of the most important things to help a GM decide if a particular disease should be included in a game is to consider the real-life experiences of the players before introducing real-world diseases into the game. Simply put be sensitive to your players and do not include any disease that either they or a loved one of theirs is coping with!

Fantasy vs. Reality

Diseases have to be separated into several categories, not least of these is whether a disease is real, fantasy, or magical. Real diseases, the ones that will be presented, actually exist. Fantasy diseases do not exist but are the product of somebody's imagination. Magical diseases are magically altered forms of real diseases. When dealing with diseases from spells a GM will have to decide if the spell infected the recipient with the real disease or just magically mimicked the disease's symptoms. This is important because a magical affliction may require a magical cure, whereas a normal disease may not require this.

Disease Categories:

There are many ways to classify the real diseases, either taxonomically, by the organ system that they affect, or by how the infectious agent spreads and replicates. This is just a short list of the many ways that the diseases can be grouped. For the purposes of these articles the diseases will be grouped into the following categories: physiological, nutrition deficiency, bacterial infection, viral infection, fungal infection, parasitic infection, or poisoning (some bacteria and fungi produce toxins that can poison food or other substances).

Germs and Culture

The type of culture a person lives in can have a dramatic effect on the type and severity of diseases that they are exposed to. A person living in a cramped house with little ventilation is more likely to get a respiratory disease (or other infectious disease) than a person who lives in a larger house with good ventilation. Other factors include clean drinking water, sanitation, personal hygiene, and thorough cooking of food especially meat. The basic idea is to reduce exposure to potentially deadly germs that are in the environment.

Another factor in disease exposure is carriers. Sometimes people get infected with a disease but do not show the normal symptoms of the disease, or they get over the symptoms, in this case the person has become a carrier, a person who shows no sign of the disease but is still able to spread the disease. There are many examples of disease carriers including Typhoid Mary, but few examples are as dramatic as entire nations of Aboriginal Americans, suffering from outbreaks of smallpox after the Europeans came to Central America. These outbreaks are particularly bad because the entire population is being exposed for the first time; this lack of immunity causes the disease to spread faster than it normally would. This presents many interesting options for role playing because PCs who travel to strange lands, might not only get sick from a mysterious disease, but may spread a disease into an area that is not prepared to handle it. This could even be used as a plot hook, if the natives view the gods as punishing them for harbouring the PCs, or if a party of good adventurers have to find a mystical cure for the epidemic that they caused.

In game terms this means that the environment can make it more likely that a PC will be exposed to a disease or that the disease may be harder to shake, in this case increase the difficulty for the saving throw / resistance roll.

The Immune System

Germs surround people all day, and most people dread this thought but is not such a bad thing. What most people fail to recognize is that some "germs" are actually very useful to humans. Yeast is a kind of fungus that can cause infections, but it is also used to make bread, and ferment grains to create alcohol. Bacteria, which can be deadly, can also be useful, people have a layer of E. coli in their intestinal track that keeps other bacteria out and supplies us with vitamin K. Bacteria such as Acidophilus and Bifidum are used to create yoghurt. Sometimes these potentially harmful germs are actually quite harmless, but sometimes they can be deadly, the difference is often how our immune system deals with them.

The Immune system is the sum total of the body's defences to fight of infection and disease. These defences can be as simple as the skin and tears that prevent most bacteria from entering the body. Or as complex as the production of white blood cells, antibodies and other immunochemicals that endlessly search the body for the slightest sign of an invader.

As the Immune system encounters a new foreign substance within the body it programs itself to be better able to deal with the substance the next time that it encounters it. It is this process that creates the immunity to certain types of disease, that is some diseases you can only catch once, after that you become immune to that disease. Of course a PC could still catch a magical form of the disease.

Glossary of Terms:

The terms below are a simplified definition that explains the words, as they will be used in these articles.

Epidemiology: Epidemiology is the study of the spread of diseases.

Infectious: The ability of a disease to spread from one person (or animal) to another. For the purposes of these articles this term will be used interchangeably with "contagious" and "communicable".

Pathogen: A pathogen is any infectious agent that can cause disease.

Poison: Any substance that interferes with life functions.

Toxin: A toxin is any poisonous substance, which is produced by a living organism.

Infection: An infection is the invasion of a microorganism into the body.

The Diseases:


Type: Nutritional deficiency. Scurvy is not an infectious disease.

Time to onset of symptoms: about 5 months.

Description: Scurvy is a vitamin C deficiency that results in a breakdown of the protein collagen, which is needed for healthy connective tissue, bones and dentin (part of healthy teeth). A lack of collagen causes the walls of the body's blood capillaries to break down causing haemorrhaging throughout the body.

Symptoms: The first sign of scurvy is raised red spots that appear around the hair follicles of the legs, arms, and back. The affected person becomes weak and has joint pain. Internal haemorrhaging causes bruise marks all over the body. The gums haemorrhage and becoming weak and soft, the teeth loosen and eating becomes difficult and painful.

Treatment/Prevention: Eat lots of citrus fruits, or take vitamin C supplements.


Infectious Agent: Listeria monocytogenes

Type: Infectious Bacterial Disease.

Description: an infection by L. monocytogenes causes swelling in the brain, the afflicted person suffers from both Meningitis and Encephalitis.

Symptoms: Causes both Meningitis and Encephalitis

Prevention/Treatment: Hygienic food processing, antibiotics (but not cephalosporins)


Infectious Agent: meningitis is caused by various pathogens including viruses, bacteria, fungi, and protozoa, Viral meningitis is the most common but bacterial meningitis is much worse.

Type: Infectious disease.

Time to onset of symptoms: often less than 24 hours.

Description: infection causes a swelling of the meninges, a protective layer of the brain. The swelling puts pressure on the brain causing brain damage and eventually death.

Symptoms: Headache, nausea and vomiting. Sometimes convulsions and coma are also present. Many people who survive often suffer from neurological damage.

Treatment: antibiotics, usually broad-spectrum cephalosporins, of course these will not be available in a fantasy setting.


Infectious Agent: Mycobacterium leprae

Type: Infectious Bacterial disease.

Time to onset of symptoms: symptoms usually occur years after infection.

Description: Unlike popular belief, people with leprosy do not have their limbs fall off, instead the calcium in the bones of the outer extremities (usually the hands and feet) is reabsorbed by the body disfiguring the affected limb. Leprosy is not very contagious; transmission usually takes close contact over a prolonged period of time. In medieval times infected people were often isolated into "leper colonies" and usually wore bells or yelled "unclean" so that people could avoid them.


There are two forms of Leprosy

Tuberculoid form: regions of the extremities lose sensation. Recovery sometimes occurs spontaneously.

Lepromatous form: disfiguring nodules appear all over the body. Deformation of the extremities and necrosis (death) of the tissue can also occur. Death is usually from complications such as Tuberculosis.

Prevention/Treatment: Usually by avoiding affected people.


Infectious Agent: Treponema pallidum

Type: Infectious Bacterial disease.

Time to onset of symptoms: varies

Description: Syphilis is a sexually transmitted disease.

Symptoms: Syphilis occurs in three stages. In the first stage one or more usually painless sores at point of contact, the sores will disappear but the person is still infected. Two to four months after infection the second stage occurs with rashes that may by accompanied by: hair loss, fever, lumps on the genitals and general tiredness. The rashes are very contagious and can last for up to two years. The third stage occurs years after the infection. This stage only occurs in a third of those infected and may involve the heart or brain. Once a person recovers the syphilis goes into remission until the incubation for the next stage is complete.

Prevention/Treatment: Safe sex reduces the risk of infection. Penicillin is the most effective treatment.

Scarlet Fever

Infectious Agent: Streptococcus pyogenes

Type: Infectious Bacterial disease.

Description: S. pyogenes produces a toxin that causes a pinkish-red skin rash, and a high fever. The tongue gets a spotted strawberry like appearance, then becomes red and enlarged.

Symptoms: a pinkish-red skin rash, and a high fever. The tongue has a spotted strawberry like appearance.



Infectious Agent: Corynebacterium diphtheriae

Type: Infectious Bacterial disease

Time to onset of symptoms: varies

Description: A tough grey membrane forms in the throat and can eventually grow to block the passage of air to the lungs

Symptoms: a sore throat and a fever followed by body aches and the formation of the membrane.

Prevention/Treatment: Antitoxin and Penicillin or Erythromycin


Infectious Agent: Clostridium tetani

Type: Infectious Bacterial disease

Description: The bacteria that cause tetanus does not spread from the initial wound site but produce a powerful neurotoxin that effects the central nervous system. The neurotoxin inhibits the body's muscles from relaxing.

Symptoms: The first symptom is called lockjaw where the muscles of the jaw will not relax, clamping the jaw shut. In extreme cases opisthotonos occurs where the muscles in the back contract forcing the head and heels backwards often fracturing the spine. Death may result from spasms of the respiratory muscles.

Prevention/Treatment: Vaccine can give immunity, treatment consists of giving Tetanus immunoglobulin antibodies.

Rheumatic Fever

Infectious Agent: Streptococcal bacteria

Type: Infectious Bacterial disease.

Description: Rheumatic fever is an autoimmune complication of a streptococcal infection. Only apply this disease after a character recovers from another disease caused by Streptococcus.

Symptoms: usually a short period of arthritis and fever. In about half of those affected an inflammation of the heart occurs damaging the heart valves, possibly causing death. Re-infection with a Streptococcal disease causes a return of the Rheumatic Fever.

Prevention/Treatment: Penicillin is used to prevent subsequent streptococcal infections.


Infectious Agent: Bacillus anthracis

Type: Infectious Bacterial disease

Description: Anthrax bacteria grows in soil and usually only affects grazing animals, however people who handle animals, animal hides or wool are at risk to infection.

Symptoms: Infection through an abrasion in the skin can cause a pustule, which can spread to septicaemia. Pulmonary anthrax is a form of pneumonia, which begins with a high fever, difficulty breathing and chest pains. This eventually leads to septicaemia and often death.

Prevention/Treatment: Antibiotics and antitoxin.


Infectious Agent: Clostridium perfringens

Type: Infectious Bacterial disease

Description: When a wound interrupts blood supply (a condition called Ischaemia the tissue can dies. Once the tissue dies gas gangrene can occur. The bacteria grow in the dead tissues and produce gases, which swell the tissue. The bacteria also produce toxins which kills cells producing more necrotic tissue. Without treatment Gangrene is 100% fatal.

Symptoms: swelling and blacking around a wound.

Prevention/Treatment: amputation of the necrotic tissue.


Infectious Agent: Yersinia pestis

Type: Infectious Bacterial disease

Time to onset of symptoms: Usually one week.

Description: Usually a disease of the rat (Rattus rattus), plague is transmitted by the flea Xenopsylla cheopis, the fleas will sometimes feed on humans infecting them with the plague. From the fleabite the plague bacteria enter the blood stream and travels to the lymph nodes in the groin and armpits which become enlarged (called buboes). Death usually occurs within two weeks of the fleabite. Once the plague enters the blood it can cause septic shock, eventually the bacteria reach the lungs causing Pneumonic Plague, which is easily spread by airborne particles. Mortality of pneumonic plague is 100% within 3 days.

Symptoms: The first signs of plague are the buboes (enlarged lymph nodes) and dark blue areas of skin which are caused by haemorrhages. Plague can also cause septic shock.

Prevention/Treatment: Antibiotics are effective and a vaccine is available. The main reason that Europe is no longer threatened by massive plague outbreaks is because the species of rats that dominate the area changed, and the flea moved on with the other rats.

Relapsing Fever

Infectious Agent: Borelia bacteria

Type: Vector borne Bacterial disease.

Description: Relapsing fever is a bacterial disease that is transmitted by tick bites

Symptoms: Fever of (40.5 0C, or 105F) which lasts 3 to 5 days. The fever can be accompanied by jaundice and rose coloured skin spots. The disease can recur up to 4 times, each time shorter and less severe that the first fever.

Lyme Disease (Lyme Borreliosis)

Infectious Agent: Borrelia burgdorferi

Type: Vector borne Bacterial disease.

Time to onset of symptoms: a few days.

Description: Lyme disease is caused by bacteria that is spread by tick bites.

Symptoms: The first symptom is a bull's-eye rash that appears at the site of a tick bite. As the rash spreads to a diameter of about 15cm, the centre of the rash clears. A couple of weeks after the tick bite flu like symptoms appear. Next evidence of heart damage appears, and often the heart requires a pacemaker. Neurological symptoms such as meningitis can occur. Years after the tick bite the character can suffer from arthritis.

Prevention/Treatment: Antibiotic treatment early works well to limit the disease.

Typhus (epidemic typhus)

Infectious Agent: Rickettsia prowazekii

Type: Vector Borne Bacterial disease.

Description: Typhus is carried by the human body louse (Pediculus humanus corporis). The bacteria grow in the louse's gastrointestinal tract and are excreted. A character becomes infected when the faeces of the louse are rubbed into a bite wound when the character scratches the bite. Usually this disease is only likely to be spread in crowded, unsanitary conditions. Mortality is high in untreated cases.

Symptoms: a high prolonged fever for two or more weeks. Stupor and a rash can also be present.

Prevention/Treatment: antibiotics such as Tetracycline and Chloramphenicol are effective. Vaccines are available for military use.

Tuberculosis "TB"

Infectious Agent: Mycobacterium tuberculosis

Type: Infectious Bacterial disease.

Time to onset of symptoms: Several weeks.

Description: People usually are infected with TB by inhaling bacteria. Once inhaled the bacteria form a lesion called a tubercle, after several weeks the tubercle has a cheese-like consistency. At this point, if the immune system overcomes the disease the lesions will heal becoming calcified. It is these calcified lesions that appear on X-rays. If the lesions do not heal the affected person becomes highly contagious.

Symptoms: Weight loss, coughing (often blood), and loss of vigour.

Prevention/Treatment: a long treatment of antibiotics.

Pertussis "Whooping Cough"

Infectious Agent: Bordetella pertussis

Type: Infectious Bacterial disease.

Description: A severe cough that can cause broken ribs.

Symptoms: At first Pertussis resembles a common cold however this progresses into prolonged coughing fits which can cause broken ribs, coughing episodes

Bacterial Pneumonia

Infectious Agent: Streptococcus pneumoniae

Type: Infectious bacterial disease

Description: The bacteria attack the lungs which respond to the infection causing a red appearance due to dilated blood vessels, the lungs begin to fill with fluid and blood cells, often an infected individual will cough up blood.

Symptoms: High fever, difficulty breathing, and chest pains.

Prevention/Treatment: treatment is usually penicillin.

Legionellosis (Legionnaires' Disease)

Infectious Agent: Legionella pneumonia

Type: Infectious bacterial disease

Description: The bacteria grow in water such as air conditioners and are then inhaled where they cause pneumonia.

Symptoms: High fever, cough, difficulty breathing.

Prevention/Treatment: antibiotics.

Shigellosis (Bacillary Dysentery)

Infectious Agent: Shigella dysenteriae

Type: Infectious bacterial disease.

Description: the Shigella bacteria produces a toxin which damages the large intestine causing sever diarrhoea, as many as 20 bowel movements a day are possible in infected people.

Symptoms: severs diarrhoea with blood and mucus in the stool, abdominal cramps, and fever.

Prevention/Treatment: antibiotics, usually Fluoroquinolones.

Salmonellosis (Salmonella Gastroenteritis)

Infectious Agent: Salmonella species.

Type: Infectious bacterial disease.

Description: Salmonella is ingested and enters the cells that line the intestines where they grow and multiply. Occasionally the bacteria enter the blood.

Symptoms: moderate fever, nausea, cramps, diarrhoea, abdominal pain and rarely septicaemia. Prevention/Treatment: Oral rehydration, but no antibiotics.

Typhoid Fever

Infectious Agent: Salmonella typhi

Type: Infectious bacterial disease.

Description: Typhoid fever is spread by ingesting food contaminated with the bacteria. The Salmonella then spreads throughout the body; patients who recover may become chronic carriers who shelter the bacteria in their gallbladder.

Symptoms: high fever, continual headache, diarrhoea (in the second or third week).

Prevention/Treatment: Antibiotics, usually cephalosporins.


Infectious Agent: Vibrio cholerae

Type: Infectious bacterial disease.

Description: The bacteria grow in the small intestine and produce a toxin that causes an extreme amount of diarrhoea. The sudden loss of fluids and electrolytes can cause shock and death. Outbreaks usually occur in unsanitary conditions.

Symptoms: "Rice water stools", vomiting, shock, and death.

Prevention/Treatment: Tetracycline, and replacement of fluids and electrolytes.

Escherchia coli Gastroenteritis

Infectious Agent: Escherchia coli

Type: Infectious bacterial disease.

Description: A mild diarrhoea that is caused by a toxin produced by E. coli in the intestines.

Symptoms: Abdominal pain, fever, and diarrhoea.

Prevention/Treatment: usually self-limiting so no treatment is necessary.


Rolemaster Diseases Summary

The Diseases listed include a level equivalent to make it easier for Game Masters who want to use these diseases with the Evil Channelling spell list "Disease".

Scurvy (Level 10)

Character looses 1 hit per day. All bleeding wounds are doubled. Healing hits takes twice as long (character heals at half the normal rate).

Listeriosis (Level 13)

Character has a 30% chance of dying. Survivors often suffer neurological damage in the form of a 2 stat penalty to memory and reasoning (50% chance for each attribute, roll separately).

Meningitis (Level 12)

Character has a 20% chance of dying. Survivors often suffer neurological damage in the form of a 1 stat penalty to memory and reasoning (50% chance for each attribute, roll separately).

Leprosy (Level 7)

This disease is listed in the evil channelling spell list "Disease".

Syphilis (Level 14)

During the first two stages of the disease the character is uncomfortable. The third stage of syphilis has a 50% of killing the character as the heart and brain are attacked.

Scarlet Fever (Level 3)

The high fever causes a 5 to all actions. The character also suffers a 15 to all perceptions based on taste.

Diphtheria (Level 20)

As the membrane grows the character will eventually suffocate. There is a 1% chance per day cumulative that the character will suffocate unless they receive treatment.

Tetanus (Level 15)

The Tetanus toxin causes a 2/day cumulative penalty to all actions that involve movement. Once the penalty reaches 100% the character can not move and suffers a B impact critical per day as their spine is bent. At this stage there is a 10% chance per day that the character will suffocate.

Rheumatic Fever (Level 11)

The fever and arthritic cause a 20 penalty to all actions during the course of the disease. There is a 15% chance that the infection will attack the heart valves. If the heart is attacked the character receives a 2 penalty to Constitution, and has a 25% chance of dying.

Anthrax (Level 30)

The character will suffer from difficulty breathing and chest pains and has a 75% chance of dying 5-7 days after the onset of symptoms.

Gangrene (Level 15)

Untreated Gangrene is 100% fatal treatment is amputation of the affected area.


This disease is listed in the evil channelling spell list "Disease".

Relapsing Fever (Level 3)

The Fever causes 5 to all actions.

Lyme disease (Level 15)

If the Lyme disease attacks the character's heart they have a 30% chance of dying. If the character suffers from meningitis use the above entry. If the character suffers from arthritis they receive a 5 penalty to all actions involving movement.

Typhus (Level 6)

Typhus causes a high fever with a 5 penalty to all actions. There is a 25% chance that the character will die.

TB (Level 19)

The character receives a 5 stat penalty to Con. There is a 35 % chance of dying.

Pertussis (Level 7)

The continual cough causes a 15 to all actions. There is a 10% chance during each coughing fit that the character will suffer an A impact critical.

Bacterial Pneumonia (Level 14)

As the disease Pneumonia listed in the evil channelling spell list "Disease".

Legionellosis (Level 14)

As the disease Pneumonia listed in the evil channelling spell list "Disease".

Shigellosis (Level 13)

Character suffers 15 to all actions and has a 15% chance of dying.

Salmonellosis (Level 14)

Character suffers 15 to all actions, and has a 20% chance of dying.

Typhoid Fever (Level 14)

Character suffers 10 to all actions, and has a 25% chance of dying.

Cholera (Level 20)

If untreated the extreme diarrhoea causes a 40% chance of dying, if treated there is only a 10% chance of dying.

E. coli Gastroenteritis (Level 15)

If untreated the diarrhoea causes a 20% chance of dying; if treated there is only a 5% chance of dying.

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