Microorganisms – Protists, Bacteria and Viruses Protists Protists are eukaryotic – Which means they are cells with a nucleus. They can be unicellular or multicellular They can be animal-like, fungus-like or plant-like. Some protists: amoeba amoeba ingesting a paramecium Paramecium paramecium05pc60x.mpeg paramecium08ob.mpeg Giardia information on Giardia Giardiasis (GEE-are-DYE-uhsis) is a diarrheal illness caused by a one-celled, microscopic parasite, Giardia intestinalis (also known as Giardia lamblia). Once an animal or person has been infected with Giardia intestinalis, the parasite lives in the intestine and is passed in the stool. The Giardia parasite lives in the intestine of infected humans or animals. Millions of germs can be released in a bowel movement from an infected human or animal. Giardia is found in soil, food, water, or surfaces that have been contaminated with the feces from infected humans or animals. You can become infected after accidentally swallowing the parasite Plasmodium Plasmodium develops in the gut of the mosquito and is passed on in the saliva of an infected insect each time it takes a new blood meal. The parasites are then carried by the blood in the victim's liver where they invade the cells and multiply. Malaria is caused by protozoan parasites of the genus Plasmodium. Malaria is currently endemic in 91 countries with small pockets of transmission occurring in a further eight countries. Plasmodium falciparum is the predominant parasite. More than 120 million clinical cases and over 1 million deaths occur in the world each year. Symptoms may appear and disappear in phases and may come and go at various time frames. These cyclic symptoms of malaria are caused by the life cycle of the parasites - as they develop, mature, reproduce and are once again released into the blood stream to infect even more blood and liver cells. When this happens a high swinging fever can develop, with marked shivering and intense perspiration. Further serious complication involving the kidneys and brain can then develop leading to delirium and coma. Bacteria Bacteria are prokaryotic cells. This means, they do NOT contain a nucleus. They have a Cell Wall and a Cell Membrane. Their genetic material (DNA) simply floats around in the cytoplasm. Many have flagella for locomotion. The structure of a bacterium e-class on bacteria Spherical Bacteria - Cocci Rod-Shaped Bacteria – Bacilli (eg. E-coli) Spirial Shaped Bacteria - Spirilla Helpful Bacteria on/in our bodies It has been calculated that the normal human houses about 1012 bacteria on the skin, 1010 in the mouth, and 1014 in the gastrointestinal tract. This number is much greater than the number of our own cells in the human body. 1014 = 100 000 000 000 000 Some bacteria are necessary for our survival. For example in the intestine we have Lactobacillus acidophilus (the most famous), Lactobacillus bifidus (more common to the baby colon), and Streptococcus faecium. Bacteria help extract water from the feces and produce Vitamin K in our large intestine acidophilus Harmful (Pathogenic) Bacteria What is E. coli O157:H7? Escherichia coli (E. coli) is a bacterium that is commonly present in the intestines of humans and animals. What makes E. coli O157:H7 so dangerous? Most strains of E. coli are harmless, the exception being the strain O157:H7 that causes severe diarrhea leading to renal (kidney) damage and other serious complications including death. E. coli O157: H7 also has the ability to cause disease at a very low dose, survive at low temperatures and under acidic conditions. Who is more susceptible to infection from E. coli O157:H7? People of all age groups are susceptible to these bacteria; however immunocompromised, elderly and young children are at a higher risk. What diseases are caused by E. O157:H7? Infection with Escherichia coli O157:H7 can range from being asymptomatic to having mild to severe gastrointestinal symptoms. These symptoms manifest as abdominal cramping, bloody or nonbloody diarrhea. In an uncomplicated case, the illness should recover in less than 5-10 days. Complications: Hemolytic uremic syndrome (HUS) is one of the complications following E. coli O157:H7 infection especially in children below the age of 5. HUS is one of the most common causes of acute renal failure in children. Hemolytic uremic syndrome is characterized by acute renal failure, and a type of anemia and fever. One-third of the children diagnosed with HUS do not recover completely and will eventually need a dialysis. The disease causing pathogen can be transmitted by: a) Eating uncooked/ undercooked ground beef b) Consumption of contaminated sprouts, lettuce, salami, unpasteurized milk c) Swimming in or drinking sewage contaminated water d) Feco-oral transmission through an infected person to a healthy individual due to unhygienic practices. spinach warning Sept 2006 latest tainted spinach linked to pigs In May 2000, seven residents of Walkerton died after drinking water contaminated with E.coli, and in April 2001, nearly 6,000 people in North Battleford became ill after drinking water contaminated with the Cryptosporidium parvum protozoan. In May 2000, bacteria seeped into Walkerton's town well. The deadly E. coli then slipped quietly through a maze of pipes and into the homes of Walkerton, Ont. Unsuspecting residents thirstily drank the polluted water and bathed in their bacteria-ridden tubs. But soon after, they began experiencing common symptoms of infection; bloody diarrhea and throbbing cramps. Seven people would eventually die and another 1286 would fall ill. The investigation which followed exposed an alarmingly unstable waterworks system made fragile by government cuts. A few diseases in humans caused by bacteria: cholera, diphtheria, leprosy, plague, pneumonia, strep throat, tetanus, tuberculosis, and typhoid fever. Antibiotics are used to kill harmful bacteria, but have the side-effect of also killing useful bacteria. Also, the over-use of antibiotics can lead to resistant strains of bacteria that are hard to fight. The CDC estimates that each year, nearly 2 million people in the United States acquire an infection while in a hospital, resulting in 90,000 deaths. More than 70 percent of the bacteria that cause these infections are resistant to at least one of the antibiotics commonly used to treat them. Some Other Harmful Bacteria Salmonella enteritidis bacterium A person infected with the Salmonella enteritidis bacterium usually has fever, abdominal cramps, and diarrhea beginning 12 to 72 hours after consuming a contaminated food or beverage. The illness usually lasts 4 to 7 days, and most persons recover without antibiotic treatment. However, the diarrhea can be severe, and the person may be ill enough to require hospitalization. The elderly, infants, and those with impaired immune systems may have a more severe illness. In these patients, the infection may spread from the intestines to the blood stream, and then to other body sites and can cause death unless the person is treated promptly with antibiotics. It can be found in Raw meats, poultry, eggs, milk and dairy products, fish, shrimp, frog legs, yeast, coconut, sauces and salad dressing, cake mixes, cream-filled desserts and toppings, dried gelatin, peanut butter, cocoa, and chocolate. Botulism Clostridium botulinum is the name of a group of bacteria commonly found in soil. These rod-shaped organisms grow best in low oxygen conditions. The bacteria form spores which allow them to survive in a dormant state until exposed to conditions that can support their growth. Botulism is a rare but serious paralytic illness caused by a nerve toxin that is produced by the bacterium Clostridium botulinum. three main kinds of botulism: Foodborne botulism is caused by eating foods that contain the botulism toxin. Wound botulism is caused by toxin produced from a wound infected with Clostridium botulinum. Infant botulism is caused by consuming the spores of the botulinum bacteria, which then grow in the intestines and release toxin. All forms of botulism can be fatal and are considered medical emergencies. Foodborne botulism can be especially dangerous because many people can be poisoned by eating a contaminated food. The respiratory failure and paralysis that occur with severe botulism may require a patient to be on a breathing machine (ventilator) for weeks, plus intensive medical and nursing care. After several weeks, the paralysis slowly improves. If diagnosed early, foodborne and wound botulism can be treated with an antitoxin which blocks the action of toxin circulating in the blood. This can prevent patients from worsening, but recovery still takes many weeks. Physicians may try to remove contaminated food still in the gut by inducing vomiting or by using enemas. Wounds should be treated, usually surgically, to remove the source of the toxin-producing bacteria. Good supportive care in a hospital is the mainstay of therapy for all forms of botulism. Botulism can result in death due to respiratory failure. However, in the past 50 years the proportion of patients with botulism who die has fallen from about 50% to 8%. A patient with severe botulism may require a breathing machine as well as intensive medical and nursing care for several months. Patients who survive an episode of botulism poisoning may have fatigue and shortness of breath for years and long-term therapy may be needed to aid recovery. Foodborne botulism has often been from home-canned foods with low acid content, such as asparagus, green beans, beets and corn. However, outbreaks of botulism from more unusual sources such as chopped garlic in oil, chile peppers, tomatoes, improperly handled baked potatoes wrapped in aluminum foil, and home-canned or fermented fish. Persons who do home canning should follow strict hygienic procedures to reduce contamination of foods. Oils infused with garlic or herbs should be refrigerated. Potatoes which have been baked while wrapped in aluminum foil should be kept hot until served or refrigerated. Because the botulism toxin is destroyed by high temperatures, persons who eat home-canned foods should consider boiling the food for 10 minutes before eating it to ensure safety. Wound botulism can be prevented by promptly seeking medical care for infected wounds and by not using injectable street drugs. MORE Anthrax Bacillus anthracis (Anthrax bacillus) Anthrax is an acute infectious disease caused by the spore-forming bacterium Bacillus anthracis. Anthrax most commonly occurs in wild and domestic lower vertebrates (cattle, sheep, goats, camels, antelopes, and other herbivores), but it can also occur in humans when they are exposed to infected animals or tissue from infected animals. Anthrax is most common in agricultural regions where it occurs in animals. These include South and Central America, Southern and Eastern Europe, Asia, Africa, the Caribbean, and the Middle East. When anthrax affects humans, it is usually due to an occupational exposure to infected animals or their products. Workers who are exposed to dead animals and animal products from other countries where anthrax is more common may become infected. Humans can become infected with anthrax by handling products from infected animals or by inhaling anthrax spores from contaminated animal products. Anthrax can also be spread by eating undercooked meat from infected animals. It is rare to find infected animals in the United States or Canada. Most (about 95%) anthrax infections occur when the bacterium enters a cut or abrasion on the skin, such as when handling contaminated wool, hides, leather or hair products (especially goat hair) of infected animals. Inhalation anthrax is usually fatal. MORE In the early 1330s an outbreak of deadly bubonic plague occurred in China. The bubonic plague mainly affects rodents, but fleas can transmit the disease to people. Once people are infected, they infect others very rapidly. Plague causes fever and a painful swelling of the lymph glands called buboes, which is how it gets its name. The disease also causes spots on the skin that are red at first and then turn black. Since China was one of the busiest of the world's trading nations, it was only a matter of time before the outbreak of plague in China spread to western Asia and Europe. In October of 1347, several Italian merchant ships returned from a trip to the Black Sea, one of the key links in trade with China. When the ships docked in Sicily, many of those on board were already dying of plague. Within days the disease spread to the city and the surrounding countryside. An eyewitness tells what happened: "Realizing what a deadly disaster had come to them, the people quickly drove the Italians from their city. But the disease remained, and soon death was everywhere. Fathers abandoned their sick sons. Lawyers refused to come and make out wills for the dying. Friars and nuns were left to care for the sick, and monasteries and convents were soon deserted, as they were stricken, too. Bodies were left in empty houses, and there was no one to give them a burial." The disease struck and killed people with terrible speed. The Italian writer Boccaccio said its victims often "ate lunch with their friends and dinner with their ancestors in paradise." By the following August, the plague had spread as far north as England, where people called it "The Black Death" because of the black spots it produced on the skin. A terrible killer was loose across Europe, and Medieval medicine had nothing to combat it. In winter the disease seemed to disappear, but only because fleas--which were now helping to carry it from person to person--are dormant then. Each spring, the plague attacked again, killing new victims. After five years 25 million people were dead--one-third of Europe's people. Gene Splicing – or Recombinant DNA Bacteria can contain Plasmids, which are circular pieces of DNA. (Bacteria don’t have nuclei.) Pieces of DNA with desired characteristics can be obtained. (eg. DNA which directs the production of human insulin or frost resistance in plants etc. etc.) A plasmid is “cut” using an enzyme. Desired DNA is inserted into the plasmid. It is “glued” back together. The plasmid is inserted into a host bacteria. The host bacteria reproduce and the offspring contain the inserted DNA (eg. to make human insulin etc.) Some of the areas where Recombinant DNA will have an impact. •Better Crops (drought & heat resistance) •Recombinant Vaccines (ie. Hepatitis B) •Prevention and cure of sickle cell anemia •Prevention and cure of cystic fibrosis •Production of clotting factors •Production of insulin •Production of recombinant pharmaceuticals •Plants that produce their own insecticides •Germ line and somatic gene therapy Proteins that HAVE BEEN manufactured using genes from bacteria Viruses Viruses are not living organisms. Without a host cell, viruses cannot carry out their life-sustaining functions or reproduce. They cannot synthesize proteins, because they lack ribosomes. They must use the ribosomes of their host cells. Viruses cannot generate or store energy because they lack mitochondria. They have to derive their energy from the host cell. They also parasitize the cell for basic building materials, such as amino acids, nucleotides, and lipids (fats). Viruses have a “protein coat” with RNA or DNA on the inside. No other organelles. T4 Bacteriophage Infecting a Bacterium animation of virus infecting bacteria flash animation of virus infecting bacteria-choose GIF animation summary below Sometimes during the process of viral replication, mutations occur. If the mutation is harmful, the new virus particle might no longer be functional (infectious). However, because a given virus can generate many,. many copies of itself, even if 200,000 particles are no good, 100 might still be just fine. Further, some mutations don't lead to harm to the virus, but instead lead to a functional but now brand-new strain of virus (Influenza virus can do this; consequently, there are several different strains of this virus which have to be identified each year in order to make a vaccine against the particular strain which might cause the "flu"). 1 Adsorption 2 Penetration 4 Late Replication 5 Maturation 3 Early Replication 6 Release The tumor viruses change cells by integrating their genetic material with the host cell's DNA. This is a permanent insertion in that the genetic material is never "removed." Several viruses have been linked to certain types of cancer: The Epstein-Barr Virus has been linked with Burkitt's lymphoma. The Hepatitis B and C viruses have been linked with liver cancer in people with chronic infections. HTLV-1, a retrovirus, has been linked to T-cell leukemia. Papilloma viruses have been linked with cervical cancer. Some viruses include: •Common cold •Arenaviruses •Cytomegalovirus •Ocular Herpes •Flu •Bunyavirus •Infant Cytomegalic virus •Meningitis •Measles •Filovirus •Progressive Multifocal Leukoencephalopathy •Encephalitis •Rubella •Flavivirus •Viral gastroenteritis •Shingles •Chicken pox •Hantavirus •Acute Appendicitis •Pneumonia •Mumps •Rotavirus •Hepatitis A •Encephalitis, •Polio •Viral meningitis •Hepatitis B •St. Louis encephalitis •Rabies •West Nile fever •Chronic Hepatitis B •Rift Valley Fever •Mononucleosis •Arbovirus •Hepatitis C •Hand, Foot, & Mouth Disease •Ebola •Parainfluenza •Chronic Hepatitis C •Hendra Virus •Chickenpox •Hepatitis D •Enteroviruses •Dengue fever •Smallpox •Hepatitis E •Astrovirus •Yellow fever •Epstein-Barr virus •Hepatitis X •SARS •Lassa fever •Dengue hemorrhagic fever •Cold sores •Japanese encephalitis The Polio Virus Polio, or more properly poliomyelitis, was one of the most feared and studied diseases of the first half of the 20th Century. It appeared unpredictably, striking its victims, mostly children, with a frightening randomness that resulted in near panic during the epidemics of the 1940s and 50s. Then, in 1955, a breakthrough occurred when, after massive field trials involving nearly two-million children, the Salk vaccine was shown to be effective in preventing the disease. Today, polio is all-but-forgotten as it has completely disappeared from developed countries, and worldwide eradication is predicted by 2005. However, polio's legacy remains. It is estimated that there are 600,000 polio survivors living in the United States, and the number worldwide must be in the tens of millions. Polio is a highly infectious disease caused by a virus poliovirus. It invades the nervous system and can cause total paralysis in a matter of hours. It can strike at any age, but affects mainly children under three. Polio is mainly passed through person-to-person (i.e., fecal-oral) contact, and infects persons who do not have immunity against the disease. There is no cure for polio, but the disease can be prevented by immunization with polio vaccine. An Influenza (flu) virus. There are billions of different flu viruses. Hepatitus A viruses Hepatitus B virus Hepatitus C viruses Hepatitis A Hepatitis B Hepatitis C How It’s Spread eating or drinking contaminated food or water. The hepatitis virus is found in faeces. It can be passed on if even a tiny amount of faeces from a person with hepatitis A comes into contact with another person's mouth Unprotected sex Contaminated needles Non-sterilized equipment for tattooing, acupuncture of body piercing, From infected mother to baby, Blood transfusions Unprotected sex Contaminated needles Non-sterilized equipment for tattooing, acupuncture of body piercing, From infected mother to baby, Blood transfusions sharing notes used to snort cocaine Symptoms •a short, mild, flu-like illness nausea and vomiting diarrhoea loss of appetite weight loss jaundice (yellow skin and whites of eyes, darker yellow urine and pale faeces) itchy skin. Some people may need to be admitted to hospital. •a short, mild, flu-like illness nausea and vomiting diarrhoea loss of appetite weight loss •jaundice (yellow skin and whites of eyes, darker yellow urine and pale faeces) itchy skin. •a short, mild, flu-like illness nausea and vomiting diarrhoea loss of appetite weight loss •jaundice (yellow skin and whites of eyes, darker yellow urine and pale faeces) itchy skin. Diagnosis and Treatment Infection with hepatitis A is usually mild, but occasionally causes severe inflammation of the liver, requiring admission to hospital. Most adults fully recover. If they continue to be infected: chronic hepatitis liver cirrhosis liver cancer. about 80% will remain infected and can pass on the virus to others. chronic hepatitis liver cirrhosis liver cancer. images of many viruses HIV viruses Human immunodeficiency virus or HIV is a retrovirus that causes Acquired Immunodeficiency Syndrome (AIDS), a condition in which the immune system begins to fail, leading to life-threatening opportunistic infections. Spread by unprotected sex and sharing needles. Mononucleosis The Epstein-Barr virus (EBV), also called Human herpesvirus 4 , is a virus of the herpes family (which includes Herpes simplex virus and Cytomegalovirus), and is one of the most common viruses in humans. Most people become infected with EBV, which is often asymptomatic but commonly causes infectious mononucleosis. It is named after Michael Epstein and Yvonne Barr, who together with Bert Achong discovered the virus in 1964 Some signs of mononucleosis •constant fatigue •fever •sore throat •loss of appetite •swollen lymph nodes (also commonly known as glands, located in your neck, underarms, and groin) •headaches •sore muscles •larger-than-normal liver and spleen •skin rash •abdominal pain Avian (Bird) Flu These influenza viruses occur naturally among birds. Wild birds worldwide carry the viruses in their intestines, but usually do not get sick from them. However, avian influenza is very contagious among birds and can make some domesticated birds, including chickens, ducks, and turkeys, very sick and kill them. The risk from avian influenza is generally low to most people, because the viruses do not usually infect humans. However, confirmed cases of human infection from several subtypes of avian influenza infection have been reported since 1997. Most cases of avian influenza infection in humans have resulted from contact with infected poultry (e.g., domesticated chicken, ducks, and turkeys) or surfaces contaminated with secretion/excretions from infected birds. Influenza A (H5N1) virus – also called “H5N1 virus” – is an influenza A virus subtype that occurs mainly in birds, is highly contagious among birds, and can be deadly to them. H5N1 virus does not usually infect people, but infections with these viruses have occurred in humans. Of the few avian influenza viruses that have crossed the species barrier to infect humans, H5N1 has caused the largest number of detected cases of severe disease and death in humans. However, it is possible that those cases in the most severely ill people are more likely to be diagnosed and reported, while milder cases go unreported. West Nile Virus West Nile virus (WNV) is a potentially serious illness. Experts believe WNV is established as a seasonal epidemic in North America that flares up in the summer and continues into the fall. About one in 150 people infected with WNV will develop severe illness. The severe symptoms can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. These symptoms may last several weeks, and neurological effects may be permanent. Milder Symptoms in Some People. Up to 20 percent of the people who become infected have symptoms such as fever, headache, and body aches, nausea, vomiting, and sometimes swollen lymph glands or a skin rash on the chest, stomach and back. Symptoms can last for as short as a few days, though even healthy people have become sick for several weeks. No Symptoms in Most People. Approximately 80 percent of people (about 4 out of 5) who are infected with WNV will not show any symptoms at all. Most often, WNV is spread by the bite of an infected mosquito. Mosquitoes become infected when they feed on infected birds. Infected mosquitoes can then spread WNV to humans and other animals when they bite. Has not been reported in BC yet, but has in Alberta and other provinces. Human Papiloma Virus Genital HPV infection is a sexually transmitted disease (STD) that is caused by human papillomavirus (HPV). Human papillomavirus is the name of a group of viruses that includes more than 100 different strains or types. Approximately 20 million people are currently infected with HPV. At least 50 percent of sexually active men and women acquire genital HPV infection at some point in their lives. By age 50, at least 80 percent of women will have acquired genital HPV infection The types of HPV that infect the genital area are spread primarily through genital contact. Most HPV infections have no signs or symptoms; therefore, most infected persons are unaware they are infected, yet they can transmit the virus to a sex partner Most women are diagnosed with HPV on the basis of abnormal Pap tests. A Pap test is the primary cancer-screening tool for cervical cancer or precancerous changes in the cervix, many of which are related to HPV. A Pap test can detect pre-cancerous and cancerous cells on the cervix. Regular Pap testing and careful medical follow-up, with treatment if necessary, can help ensure that pre-cancerous changes in the cervix caused by HPV infection do not develop into life threatening cervical cancer.