Pathogenic Microbes


genus contains only one species that is highly pathogenic to humans - B. anthracis. This pathogen causes the disease Anthrax and is typically associated with domestic livestock and only rarely in man. Most species of Bacillus are saprolytic and are found on vegetation, and in the soil, water, and air. Anthrax spores are relatively resistant to chemical and thermal destruction. Spores can remain viable for years in the environment. B. cereus has been associated with food poisoning particularly due to it's production of enterotoxins. Mastitis has also been shown to be caused in some instances be B. cereus. The spores of this species are also hardy and can be found in a wide variety of foods including meat, dairy products , vegetables, and fish. Infection or food poisoning typically occurs because of improper cooking or preparation of food - nonpasteurised milk, unwashed vegetables, under-cooked meat, poultry, and fish.


the causative organism responsible for whooping cough is B. pertussis. It is an extremely delicate microbe surviving for only a short time outside respiratory secretions. Humans are the only species which are naturally infected with this disease. This is a highly contagious disease affecting an estimated 9 out of 10 persons worldwide, usually in childhood. Mortality rates for whooping cough have dropped significantly since the widespread use of active immunization programs have been put into place.


This bacterial genus is the causative agent responsible for the disease Brucellosis. Passed through various types of animals humans become infected by coming into contact with animals or animal products that are contaminated by these bacteria. Incidence of infection by humans is not great. Symptoms can be similar to flu - severe infection may lead to the central nervous system - (CNS) or endocarditis. This can also be a chronic type of infection causing long term symptoms including recurrent fevers, arthritic conditons, and fatigue. Contaminated milk which is not pasteurised is probably the most common route of infection for humans. Best form of protection is not to consume non-pasteurised milk or other dairy products which have not been pasteurised.


Pathogenic to many species of mammals. In the case of livestock, C. fetus causes miscarriage in sheep and cattle. Common cause of food poisoning in humans is attributed to C. jejuni, usually associated with eating improperly prepared or under-cooked chicken and other poultry. It has been reported that as much as 90% of chickens carry this microbe. Sources also include other meats, unchlorinated water and unpasteurised milk. Infection causes acute gastroenteritis, fever, headache, and joint and muscle pain; possible nerve damage and with death possibly occurring in severe cases. Carriers of this disease include poultry, cattle, pigs, sheep, rodents, and birds.


Members of this group of fungi (yeast) are usually not pathogenic in healthy humans. In fact C. albicans and other species of Candida are typically present on the normal mucousal membranes of the mouth, vagina, and intestinal tract. However under certain conditions, such as, malignancy, diabetes, treatment with wide spectrum antibiotics, treatment with corticosteroids or in immunosuppressed individuals these microbes can behave as virulent pathogens (Candidiasis). As opportunistic pathogens C. albicans and other members of this species can establish a variety of chronic or acute, localized or widely spread lesions. Thrush (oral candidiasis) is characterized by discrete or confluent white patches of the mouth and pharynx. Vaginal candidiasis also known as vaginal thrush occurs during pregnancy, in diabetes, urinary tract infection, and following treatment with antibiotics. Invasion of bronchial and pulmonary tissues with C. albicans causes bronchopulmonary candidiasis which is usually secondary to carcinoma. The skin can also be infected with C. albicans, particularly in areas that are constantly wet and macerated - interfriginous candidiasis. Invasion of heart tissue (endocarditis) though rare has been observed. Also it has been pointed out recently that recurrent ear infections and hyperactivity in children may, in at least in part, be due to C. albicans infection


This sexually transmitted disease (STD) commonly referred to as the "silent epidemic" is caused by the bacterium C. trachomatis. The incidence of Chlamydia infection is greater then either gonorrhea and syphylis It is the most reported infection in the Umited States where some 3-4 million individuals contract this disease each year. Unlike these later two types of STD infections Chlamydia infection typically has no telltale symptoms, thus most people who are infected do not even know they carry the disease. The seriousness lies in the fact that if this disease is left untreated it can cause serious reproductive organ damage and infertility problems in latter life. The disease condition conjunctivitis is caused by another member of the genus Chlamydia - C. psittaci. Usually a mild type, easily treated, infection of the eye and surrounding area also known as "pink eye". Symptoms include red eyes with swollen lids which are stuck together in the mornings - very similar to infections of the eye. Recently it has reported that another member of the genus Chlamydia - C. pneumoniae is a new emerging infectious agent implicated in artheosclerosis. Much less famous as compared to the other members of this group C, pneumoniae is commonly spread through coughs and sneezing. It typically, causes flu-like respiratory symptoms that can progress to pneumonia. There is mounting evidence that a high proportion of adult humans wordwide are carriers, implying a high incidence of infection with this microbe. The interest here lies in the fact that the evidence so far suggests that C. pneumoniae can infect the walls of blood vessels, inducing inflammation, and possibly causative of heart disease, heart attack, and stroke. Thus these results suggests that infection may be, at least in part, responsible for heart disease.


The genus contains species which primarily inhabit the soil but may be found in the intestinal tracts of humans and other animals. In most instances these species are pathogenic to man. The pathogenicity of these microbes is associated with the exotoxins - which are neurotoxins - that the individual species produce. In the case of C. botulinum, which causes Botulism in humans, an exotoxin - botulinum toxin - which causes the pathogenicity. In humans botulism is normally an intoxication which results from the ingestion of food, containing the toxin. This potentially fatal disease state results from the ingestion of uncooked or improperly prepared food of animal origin or improperly canned fruits and vegetables, in which contaminating spores of the organism have germinated and produced the toxin. The resulting toxemia is caused by the exotoxin produced by the microbe. Thus botulism is not an infection and is not the direct result of colonization of C. botulinum in the DI tract. The spores of this pathogen are relatively heat and pressure resistant whereas the produced toxin is heat labile. The causative organism of Tetanus - C. tetani is normally present in the soil and intestinal tract of various animals. Only rarely is it present in the intestinal tract of humans. Similar to Botulism this disease state is caused by the exotoxin , which is also a neurotoxin, produced by the organism. Thus the disease Tetanus only appears only when spores of C. tetani germinate after gaining access to wounds. The highly invasive infection Gangrene is most commonly associated with the species C. perfringens. Though not pathogenic when introduced to healthy tissues; when introduced to preexisting tissue injury, especially muscle, can be responsible for rapid devastating infection characterized by production of gas and destruction of muscle and connective tissue. As with the other members of the genus Clostridium the associated pathogenicity of this organism is due to the exotoxin which is produced. In the case of this toxin it is a histotoxin which has necrotizing and hemolytic properties which may cause death if left untreated. Though normally commensal in the human intestinal and genital - urinary tracts of humans C. perfringens may be pathogenic and causative of wound infections, uterine infections, bacteremia, and enteric infections. C. perfringens is a leading cause of food poisoning ranking only second to S. aureus in frequency of outbreaks. Another member of this genus - C. difficile can exist as part of the normal intestinal flora of children under the age of two years. It normally less present in children over the age of two. As a pathogen C. difficile is the major cause of pseudomembranous colitis and antibiotic associated diarrhea. This disease condition occurs when the delicate microbial balance of gut is altered allowing C. difficile to flourish and produce a toxin which causes a watery diarrhea. The overuse of antibiotics and invasive treatment can increase risk of developing the disease. Typical symptoms include frequent, foul smelling, watery stools. Abnormal heart rhythm is sometimes observed as well as blood and mucous in the stool. Disease is spread through contaminated stool which contains spores of the bacterium. The spores are quite robust and can survive in the enviroment for several months. Person to person contamination is typically via the hands of health care persons who come in direct contact with infected patients or contaminated surfaces. Proper sterile technique, wearing of latex examination gloves….etc, and proper handling of contaminating waste helps lower incidence of this disease.


A coccidian protozoa microscopic parasite responsible for the diarrheal disease - Cryptosporidosis. The species responsible C. parvum can live in the intestine of infected humans & domestic animals. Its mode of transmission is by way of infected stool. The disease and causative parasite are both known as "Crypto". The oocysts or spores are quite hardy due to their outer coat and are quite resistant to long periods outside a host and to chorine disinfection. They are however effectively removed from the water supply by filtration. Crypto may be found in soil, food, water or on other surfaces contaminated with infected feces. Because of this and other features of this hardy parasite - Crypto has become recognized as one of the commonest waterborne diseases (drinking and recreational) in humans worldwide. Symptoms include diarrhea, loose or watery stool, stomach cramps, upset stomach, and fever. In most cases the disease usually subsides within 30 days but in some cases may be prolonged and even prove fatal in individuals that are immuno-compromised - cancer patients and elderly. Crypto is commonly referred to as "AIDS diarrhoea". It should be pointed out that some individuals infected with this parasite are asymptomanic - show no symptoms.


This parasite occurs in tropical or temperate climates wordwide. Primarily a water-borne disease but also associated with raspberries, lettuce, and fresh basil is caused by C. cayetaninsis. The symptoms include a watery, sometimes explosive diarrhoea in humans. Incubation period is approximately one week after ingestion of contaminated food prior to condition becoming symptomatic. Transmission is by way of contaminated feces which invades surrounding soil, water, and vegetation.

Escherichia coli

Included in the Coliform group E. coli is sometimes referred to as the "colon bacillus" as it is the predominant species found in large bowel of humans. Public health laboratories use this microbe as a marker when testing water supplies - presence indicates fecal contamination. In humans, diseases caused by E. coli are typically associated with the urinary tract. Though for the most part commensal there have been 14 strains of E. coli that can be pathogenic causing diarrhea or dysentry in man, especially in infants and the elderly-enteropathogenic E.coli. One such strain E. coli 0157:H7 is commonly referred to as as enterohhemorragic E. coli (EHEC) has been implicated with various outbreaks of food poisoning world wide. This pathogen produces toxins known as verotoxins which is responsible for causing hemorrhagic colitis or bloody diarrhoea. Long term complications can lead to such diseases as hemolytic uremic syndrome. Cattle appear to be the principle reservoir of this pathogen although person to person contact, ingestion of contaminated water or food can lead to infection. In humans transmission is principally through the ingestion of infected foods, which are under cooked and raw milk (unpasteurised). Apple juice, yoghurt, cheese, salad vegatables and corn have also been implicated.


Is disease caused by the microscopic parasite Giardia instestinalis - also known as Giardia lamblia. This one celled organism typically lives in the intestine of infected animals and man where transmission of infection is by way of infected stool. ". The oocysts or spores are quite hardy due to their outer coat and are quite resistant to long periods outside a host. In the last 20 years Giardia has become recognised as one of the most commonest waterborne diseases in the world. Typically symptoms include diarrhoea, watery stool, stomach cramps, and upset stomach. First symptoms usually become noticable some 1-2 weeks after being exposed and in other wise health individuals will last some 2-6 weeks. However in individuals who are immuno-compromised infection can be prolonged and may lead to complications. Similar to other waterborne diseases Giardia can be found in soil, food, water, and on other surfaces which have been contaminated with the feces of individuals infected with the disease. This is especially true where water supplies are not treat by chemicals (chlorine) and or filtration to minimize risk of infection.


H. pylori is a newly discovered stomach infection which was first reported in 1983. This bacterium is present in approximately 50% of the people in the world. Most do not exhibit any pathogenesis, but all have an inflammation of the stomach lining, a condition which is called "gastritis". Gastritis is the underlying condition which causes ulcers, and other digestive complaints, possibly including cancer of the stomach. Mode of transmission is by way of oral contact. It is of interest that H. pylori infects approximately 20% of persons below the age of 40, and approximately 50% of individuals over 60 years of age. Further, H. pylori infection is uncommon in children.


Discovered some 100 years ago H. influenzae is the most common form of bacterial meningitis affecting usually children and young adults. Natural acquired disease due to H. influenzae appears to only occur in humans. This disease usually begins as a nasopharyngitis (cold). Although this disease can be fatal early diagnosis and treatment can lead to full recovery.


Since before the end of the 19th century it has been widely accepted that K. pneumoniae is a significant respiratory pathogen. It has been shown that this organism causes serious urinary and pulmonary infections in hospitalized patients. K. pneumoniae is found in the respiratory tract and feces of 5 -10 % of normal healthy individuals. It is also frequently present as a secondary infection in patients suffering from chronic pulmonary disease.


The disease in the form of L. monocytogenes has long been recognized as opportunistic pathogen affecting both animals and man. This bacterium has been isolated from a wide range of environments, including vegetation, soil, animal feed, sewage and water. It is also found in a wide variety of raw and processed foods - such as in dairy products (milk & cheese), meat and meat products, poultry, and seafood products (fish & mussels) The disease preferentially affects individual who are immuno-compromised including pregnant women, newborn babies, and the elderly. It is characterized by monocytosis, septicemia, visceral abscesses; meningoencephalitis and uterine and fetal involvement have also been described. In the later this can lead to fetal death, miscarriage or stillbirth. The mortality rate of untreated patients suffering from associated meningoencephalitis or meningitis is approximately 70%. In adults the infection is typically superimposed on an underlying primary disorder - neplastic disease, organ transplant, diabetes. In addition infection is also associated radiation therapy and corticosteroid treatment.


see Neissaria


Range from harmless inhabitants of soil and water to highly pathogenic microbes - M. tuberculosis and M. lerae which are responsible for two devastating diseases that can inflict humans, Tuberculosis (TB) and Leprosy. Chemotherapy of both these diseases has proven beneficial. In the case TB the antibiotic streptomycin has been credited with the initial success in eradicating this past widespread epidemic. Although it should be pointed out that antibiotic resistant strains of M. tuberculosis commonly referred to as multi-drug resistant tuberculosis or MDR-TB are on the increase, especially involving AIDS patients. Current methods, such as thalidomide treatment have proven to be effective in treating leprosy. Other species of this genus are also pathogenic to man and other animals. In the case of M. bovis it enters humans via the intestinal tract following the ingestion or infected raw milk (unpasteurised). A localized intestinal infection thus spreads to the respiratory tract where in due course classic symptom of tuberculosis develop. Another member of the genus - M. paratuberculosis or Johne's Disease causes a devastating non-treatable fatal disease in cattle, sheep and goats. Recently a great deal of evidence has been brought forth linking M. paratuberculosis with the human diseases Chrohn's Disease, sarcoidosis, and ulcerative colitis. The symptoms of these diseases is similar to that of intestinal tuberculosis (caused by M. tuberculosis)


members of this genus are the smallest organisms lacking cell walls that are capable of self replication. They cause various diseases in man, animals, and plants. It is reported that seven species of this genus cause disease in humans. An important pathogen causing pneumonia and other respiratory diseases in humans is M. pneumoniae. This pathogenic organism is also associated other areas of the body which include manifestations such as hematopoietic, joint, central nervous system, liver, pancreas and cardiovascular syndromes. A causative microbe associated with urethritis is M. genitalium. A recent study reported that this organism was present in urogenital specimens collected from 60% of male homosexual patients with recurrent or persistent nongonococcal urethritis compared to only 22% of heterosexual patients suffering from the same condition and only 9% of men without urethritis. M. fermenfans also known as M. incognilus is condidered to be a commensal organism (not harmful) in humans often found in the urogenital tract, in saliva and the oropharyngeal area. It has been proposed that M. fermentans, M. pirum, M. hominis, and M. penetrans are human pathogen and possibly act as cofactors in HIV infection. It has been postulated that these organisms possibly contribute to the variation in duration from exposure to HIV infection to full blown AIDS symptoms. Of recent note is the association of Mycoplasma infection with such varied disease states as Chronic Fatigue Syndrome (CFC) sometimes called Myalic Encephalomyelitis, Fibromyalgia Syndrome (FS), Gulf War Syndrome (GWS), Chrohn's Disease and Arthritis. Though not yet conclusive the evidence is compelling.


Mycotoxins are the toxic products of certain microscopic fungi which develop on or in certain foodstuffs derived from both plants and animals. They are found throughout the whole food chain. Literally hundreds of these mycotoxins have been identified. It has been said that based on the implications on human health and the economy, mycotoxins are by far the most significant contaminates of our food supply.


One member of this group of bacteria is N. meningitis which is also known as Meningococcus. This microbe is responsible for the potentially fatal bacterial infection - meningococcal meningitis. This disease causes swelling or inflammation of the membranes surrounding the brain and spinal cord. Symtoms include fever, severe headache, stiff neck, nausea followed by vomiting, rash, and lethargy. This is a serious infection which can cause permanent disability - including hearing loss and brain damage. Despite antibiotic treatment menigococcal meningitis can prove to be fatal to approximately 10% of the individuals who contract this disease. In some cases the menigococcal bacteria can infect the blood - which is termed meningococcemia. Also a very serious condition which can lead to kidney and heart failure , and like the other type of meningococcal infection can cause serious permanent damage and death - approximately 20% of the individuals who contract this infection succumb to the disease. Being the second most common cause of bacterial meningitis - see Hemophilus - N. meningitis is responsible agent for between 3,000 to 4,000 reported cases in the United States each year. Transmission of this disease is by direct contact with infected individuals - sharing a drink, food, kissing or through sneezing & coughing. Individuals at risk are typically reside in high density housing, such dormatories. University students have recently been identified as a highly at risk group. Currently there is an effective vaccine available that can prevent infection against four of the five strains of the disease (serogroups A, C, Y and W-135). These four subgroups are responsible for approximately 65% of reported cases of meningococcal meningitis. Unfortunately at this time there is no vaccine available for fifth strain - serogroup B.


Is caused by another member of this genus - N. gonorrhoeae. A widely spread form of sexually transmitted disease (STD) affecting humans. The disease causes pain as well as discomfort and can lead to many disorders of the reproductive system - including sterility in both sexes, blindness, arthritis, and even death if left untreated. Antibiotic resistant strains are on the increase.


A prion is the smallest known particle capable of passing on infection. Transmissible spongiform encephalopathies in humans and animals are caused by these agents. These disease conditions include Scrapies in sheep, Bovine Spongiform Encephalopathy (BSE) in cattle - also known as Mad Cow, and Creutzfeldt Jacob Disease (CJD) in humans.


Is the causative bacteria of the holes observed in Swiss cheese. It has been estimated that 80% of teens suffer from the condition Acne vulgaris which is caused by the species P. acnes. This condition is characterized by red inflamed pimples, pus filled whiteheads and blackheads found on the skin.


As a group contain a wide variety of species which are pathogenic and potentially fatal for man or other animals. In many cases they are pathogenic for both man and animals. Three clinically discernable syndromes of Salmonellosis occur in man and animals: enteric fever, septicemia, and acute gastroenteritis. One type of enteric fever affecting man is the potentially life threatening disease Typhoid fever. This disease caused by S. typhi is acquired by the ingestion of contaminated food or water. Salmonella septicemias are most commonly caused by S. choleraesuis. The two most common causes of gastroenteritis (food poisoning) associated with Salmonella in man are S. enteritidis and S. typhimurium.


Associated with eggs is an important health issue around the world. The bacterium, S. enteritidis is the causative agent - even perfectly normal looking eggs can be affected. The problem arises when eating raw or under cooked eggs infected with this bacterium - which can cause illness and possibly hospitalization. Symptoms typically include fever, abdominal cramps, and diarrheea beginning some 12 to 72 hours after consuming the infected food. In most case the illness runs its course over 4 to 7 days and most persons recover without need for pharmaceutical intervention. In certain instances however the infection can lead to severe diarrhea and the infected individual may require hospitalization. Infants, the elderly, and immuno-compromised individuals are more predisposed to contracting the severe symptoms associated with this disease which if not treated may prove fatal.

Salmonella typhimurium DT 104

Is attracting a great deal of attention from the public health sector as it is causing an increasing number of salmonellosis cases in humans. The source of the foodborne infection are contaminated meat products usually sausages and hamburgers. Unfortunately the organism is hard to treat as it is resistant to a wide range of antibiotics and thus illness can be prolonged or even fatal, especially in the immuno-compromised - approximately in 3% of the cases seen. Though primarily associated with cattle, this pathogen has spread to a wide range of farm animals including pigs and chickens. Is has been reported to account for and responsible for nearly 60% of S. typhimurium and 30% of all Salmonellosis cases.


All known species of the genus Shigella are bacteria pathogenic for man. First described in the fourth century B.C. Shigellosis is a disabling highly infectious disease caused by the pathogen S. flexneri and S. dysenteriae. It spreads rapidly under conditions of overcrowding and poor sanitation. Typically seen in disaster areas and other times of destruction such as war. Though much less invasive as compared to Salmonella this disease is a significant cause of infant mortality in developing countries. Shigella species are commonly pathogenic to humans, causing severe gastroenteritis (bacillary dysentery). In healthy adults, dysentery is a self-limiting disease, but it can be fatal to infants, young children, and individuals who are immuno-compromised. Symptoms include fever, cramps, and loose stools containing blood and mucous - which are caused by inflammation which accompanies bacterial invasion of the intestinal epithelial cells -thereby causing tissue necrosis and destruction. In the case of some strains they produce enterotoxin and Shiga toxin which is very similar to E. coli 0157:H7 Transmission is usually via the fecal-oral route with contaminated feces infecting water supply and unsanitary food handling being most common mode of transmission. Contaminated foods can include salads (potato, chicken, tuna etc) , raw vegetables, and dairy products. It has been estimated that approximately 300,000 cases of shigellosis occur annually in the United States. Shigellosis accounts for less than 10% of reported outbreaks of foodborne illness in the USA. Infants, the elderly, and infirmed patients are most susceptible to contracting this disease. Shigellosis is a common disease associated with individuals suffering from HIV or AIDS, AIDS-related complex, as well as non-AIDS homosexual men.


as a group are common bacteria that effect both humans and animals. In humans, two species are important: S.epidermidis, a usually nonpathogenic bacteria found on the skin and mucous membranes; and S. aureus, a potential disease causing bacteria which is associated with pneumonia, osteomyelitis, carditis, meningitis and arthritis. The S. aureus bacterium is found upper respiratory tract, especially the nose and throat. Certain strains of S. aureus have been implicated as the causative agents responsible for the phenomenon known as "Toxic Shock Syndrome". One of the leading causes of food poisoning in the United States has been attributed to S. aureus. Methicillin is antibiotic which is typically used to treat Staphylococcus or Staph infections. In recent years there has been a dramatic increase in S. aureus infections that are resistant to this antibiotic - Methicillin Resistant Staphylococcus aureus (MRSA). Of further interest is the dramatic rise in S. aureus outbreaks in hospital wards throughout the world. As was mentioned S. epidermidis is a common member of the normal flora of the skin and mucous membranes. However the pathogenic form of this organism has become one of the most important agents responsible for hospital acquired infections. Two unique features of this organism unfortunately make this an ideal infectious agent in a hospital environment. Firstly, the hydrophobic nature of the organisms cell membrane facilitates its adherence to synthetic surfaces or devices, and to damaged heart valves. Secondly, after colonization and establishment of infection a protective slime or biofilm is synthethized by the organism which acts as a protective sheet. In the first instance prosthetic devices, such as synthetic heart valves, and inserted catheters are ideal sites of infection. This is especially true in individuals who are immuno-compromised, such as the infirmed hospital patients and the elderly where fatalities have been observed. In the second instance the produced protective coating along with the fact that many isolates of this organism have been shown to be multiple antibiotic resistant - MAR makes this a very serious type of infection.


contain several species which are potent pathogenic bacteria that effect both humans and animals. Virulent forms of S. pyogenes and S. pueumoniae can cause infection, especially when the host's immune system is compromised. S. pyogenes is the leading cause of streptococcal pharyngitis or "strep throat". This bacteria can also cause infections of the inner ear, tonsils, and mammary gland. Mastitis is an infection of the mammary gland caused by S. agalactiae. The other pathogenic species, S. pneumonia, causes lung infections and may lead to meningitisis. Peridontal disease and tooth decay have been associated with S. mutans. Thus the evidence poses the theory that dental disease may be because of infection. Possibly even more of interest is that S. mutans and S. sanguis have been linked with subacute bacterial endocarditis. An ever increasing trend is being observed in antibiotic resistance especially in S. pneumoniae.

Streptococcus agalactiae

Once was thought only to infect cows where it is a causative agent of the disease - mastitis. However, now it is recognized that this organism can cause serious disease - bacteremia and meningitis. This is especially true in immuno-compromised individuals such as the newborn and the elderly. Infections of the newborn are the most common and are extremely serious. There two types, one with early onset of infection starting several days after birth leading to bacteremia and pneumonia with infection occurring during the normal birthing process as baby passes through the birth canal. Approximately 25% of young womens' birth canals are colonized with Group B Strep of which this species is a member. The second type of infection is meningitis which occurs somehat latter - 10th to 60th day after birth. In each of these cases mortality can be high reaching 50 - 70%. As was mentioned previously virulent forms of S. pyogenes and S. phueumoniae can cause infection, especially when the host's immune system is compromised. S. pyogenes is the leading cause of streptococcal pharyngitis or "strep throat". This bacteria can also cause infections of the inner ear, tonsils, and mammary gland. - there has recently been an increase in variety, severity and invasiveness associated with infections of this organism. An example are the reported cases of "flesh eating bacteria" which is associated with S. pyogenes. Scarlet fever, a once serious complication of Strep infection has for the most part been completed eradicated due to antibiotics. Invasive infections of these species can cause necrotizing faciitis, myositis, streptococcal shock syndrome, toxic shock syndrome, acute rheumatic fever, and acute glomerulonephritis. I


Is a sexually transmitted disease (STD) transmitted by the bacteria Treponema pallidum. The initial infection causes ulceration at the site of the infection. As the disease develops and moves throughout the body it can damage many organs. If left untreated this disease will cause serious coronary distress, mental disorders, blindness, various neurologic problems and finally death.


Primary host of this parasitic is the cat and transmission to humans is via infected feces. The disease T. gondii can occur through ingestion of improperly cooked meat from intermediate host such as goats, pigs, cattle, and poultry. The disease Toxoplasmosis in humans typically produces mononucleosis type symptoms (glandular fever). Transplacental infection can lead to fetal distress, brain damage and possible fetal death. In the case of immuno-compromised individuals infection can cause pneumonitis, myocarditis, meningoencephalitis, hepatitis, and chorioretinitis. Infection is typical in AIDS or HIV patients which usually exhibit cerbral toxoplasmosis.


see Syphilis


The causative organism of the disease cholera is V. cholerae. This is a severe diarrheal disease affecting humans. Mode of transmission is by way of contaminated feces present in food and water. A natural reservoir for this pathogen is not known but is thought to be aquatic. The infective bacterium produces a cholera toxin which is an enterotoxin whose actions on the mucosal epithelium is responsible for the characteristic diarrhea - massive loss of fluid - associated with this disease. In extreme conditions death can be observed within 2-3 hours following onset of symptoms. Untreated cholera typically results in high (50 -60%) mortality rates. Treatment consists of fluid and ion replacement via intravenous drip. Antibiotics have shown little help in treating this disease. Yersinia as a genus contains three speicies one of which is Y. pestis the causative organism of Bubonic Plague. The other two species Y. pseudotuberculosis and Y. enterocolitica are also capable of causing disease in man. Clinical symptoms in humans are typically observed as entercolitis. A septicemic potentially fatal form, resembling typhoid fever can also be observed. This typically is observed in patients suffering other underlying diseases such as cirrohisis of the liver and or blood dyscrasias. This foodborne infection is typically acquired by eating under cooked or ill prepared food, usually pork, and milk products. Transmission is via oral fecal route and infection may be passed by drinking contaminated unpasteurised milk or water. Hands soiled with the contaminating microbe can also transmit infection during food preparation.


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