Host-Microbe Relationship - College of Public Health PDF

upcph HOST-MICROBE RELATIONSHIP AZITA RACQUEL G. LACUNA, RMT, DMM, MPH DEPARTMENT OF MEDICAL MICROBIOLOGY COLLEGE OF PUBLIC HEALTH UNIVERSITY OF THE PHILIPPINES MANILA SEAMEO TROPMED Regional Centre for Public Health, Hospital...

upcph HOST-MICROBE RELATIONSHIP AZITA RACQUEL G. LACUNA, RMT, DMM, MPH DEPARTMENT OF MEDICAL MICROBIOLOGY COLLEGE OF PUBLIC HEALTH UNIVERSITY OF THE PHILIPPINES MANILA SEAMEO TROPMED Regional Centre for Public Health, Hospital Administration, Environmental and Occupational Health OBJECTIVES To know the relationship between agent, host and environment To enumerate the different symbiotic relationships To identify the different frequency and distribution of disease To learn the different modes of transmission of common infectious diseases To have a background of the human immune defenses OVERVIEW Humans are constantly exposed to microbes in their environment, mostly without harm. When microbes colonize the human body, sometimes they become part of the normal flora and other times, they may cause infection and disease. Normal flora are bacteria, fungi, and protozoa that reside naturally in the skin, gastrointestinal tract, mucous membranes, and genitourinary tracts, where they provide a stabilizing balance. COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health OVERVIEW Pathogens invade the body and cause harm to the tissues by means of virulence factors. An infection occurs when an adequate dose of pathogens gains access to the body through a certain route, and subsequently adheres, grows, and disrupts tissues. COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health  PATHOLOGY, INFECTION, AND DISEASE Pathology is the scientific study of disease (pathos = suffering;logos = science) Etiology-the cause of disease Pathogenesis-manner in which a disease develops Infection- invasion or colonization of the body by pathogenic microorganisms Disease -occurs when an infection results in any change from a state of health COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health  NORMAL MICROBIOTA Animals, including humans, are generally free of microbes in utero. At birth, normal and characteristic microbial populations begin to establish themselves The newborn's first contact with microorganisms is usually with lactobacilli, from the mother’s vagina -become the predominant organisms in the newborn's intestine. COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health  NORMAL MICROBIOTA Other bacteria acquired from foods begin to inhabit the large intestine. These microorganisms remain there throughout life and, in response to altered environmental conditions, may increase or decrease in number and contribute to disease COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health  NORMAL MICROBIOTA Normal microbiota – Transient microbiota- permanent residence present for several days , (colonize) but that do weeks, or months and not produce disease then disappear under normal conditions COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health  RELATIONSHIPS BETWEEN THE NORMAL MICROBIOTA AND THE HOST Microbial antagonism, or competitive exclusion-normal microbiota can benefit the host by preventing the overgrowth of harmful microorganisms competing for nutrients producing substances harmful to the invading microbes affecting conditions such as pH and available oxygen Disease-balance between normal microbiota and pathogenic microbes is upset COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health NORMAL MICROBIOTA OF A HUMAN COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health SYMBIOSIS relationship between the normal microbiota and the host a relationship between two organisms in which at least one organism is dependent on the other COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health SYMBIOSIS Symbiosis refers to living together of two or more different organisms A number of interactive associations can occur Mutualism Commensalism Parasitism  MUTUALISM Describes an association where both organisms benefit from the association. The partners maybe: Microbe/microbe Microbe/plant Microbe/animal MUTUALISM  COMMENSALISM One organism benefits, the other is unaffected Refers to an association where one partner, the commensal, benefits from the association while the other partner, the host is neither harmed nor helped Many organisms are part of the normal body flora  COMMENSALISM Although many are considered commensal, disruption of the normal flora may allow overgrowth and disease (thrush, oral yeast or yeast vaginitis) Candida spp. in the skin or vagina may be commensal but entry of the same organism into tissue or blood results in infection.  PARASITISM Association where one organism, the parasite benefits while the other or the host is harmed. Many of the disease-causing bacteria are parasites  OPPORTUNISTIC PATHOGENS cause disease when the host’s defenses are compromised or when they become established in a part of the body that is not natural to them. not pathogenic to the normal, healthy person and do not usually have well-developed virulence properties COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health  upcph CLASSIFYING INFECTIOUS DISEASES  DISEASES Communicable disease- any disease that spreads from one host to another, directly or indirectly chickenpox, measles, genital herpes, typhoid fever, and tuberculosis Contagious diseases-easily spread from one person to another Non-communicable disease-does not spread from one host to another. COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health Epidemiologic Triangle Model Host COMMUNICABLE DISEASE MODEL Agent the element that must be present in order for the diseases to occur.  Microorganisms algae bacteria fungi protozoa viruses Microorganisms virus protozoa bacteria bacteria bacteria virus bacteria bacteria virus Microbes come from plants air soil people animals water COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health COMMUNICABLE DISEASE MODEL Host Certain individuals are more vulnerable to infectious diseases or the more severe form of the illness. COMMUNICABLE DISEASE MODEL Environment air, soil, water, climate change, and other factors that influence the spread of infectious diseases  EQUILIBRIUM BETWEEN THE POPULATION, INFECTIOUS AGENT, AND THE ENVIRONMENT HOST Age Genetic make up Poverty Nutritional status Previous exposure Immunization status General physical condition Communicable Disease AGENT ENVIRONMENT Virulence Infectious dose Shelter , Altitude , Humidity Susceptibility to drugs Sanitation , Food supply Mode of transmission Water supply , Climate change Ability to adapt to change Overcrowding THE COMMUNICABLE DISEASE CYCLE NOTIFIABLE DISEASES Agents A. Acute bloody diarrhea - Shigella - Dengue, Ebola virus, B. Acute hemorrhagic fever Marburg virus C. Acute febrile illness - Leptospira interrogans D. Acute lower respiratory tract infection & - S. pneumoniae, pneumonia Haemophilus pneumonie, Klebsiella pneumoniae E. Acute watery diarrhea F. Cholera -rotavirus -Vibrio cholera G. Dengue hemorrhagic -Dengue virus fever H. Diphtheria I. Filariasis -Corynebacterium diphtheriae -Wuchereria bancrofti, Brugia A. Leprosy malayi -Mycobacterium leprae B. Leptospirosis -Leptospira interrogans NOTIFIABLE DISEASES Agents -P. falciparum A. Malaria -measles virs B. Measles -Neisseria meningitidis C. Meningococcal infection -Clostridium tetani D. Neonatal tetanus E. Non-neonatal tetanus D. Paralytic shellfish poisoning -toxin-contaminated bivalve (PSP) shellfish and crustaceans A. Rabies (human) -rabies virus -Schistosoma japonicum B. Schistosomiasis -Salmonella typhi C. Typhoid & paratyphoid fever -Salmonella paratyphi D. Viral encephalitis -HSV, Japanese encephalitis E. Viral hepatitis -Hepatitis A, B, C F. Viral meningitis -HSV G. Whooping cough - Bordetella pertussis  OCCURRENCE OF A DISEASE Symptoms-changes in body function, such as pain and malaise (a vague feeling of body discomfort ). Signs- objective changes the physician can observe and measure ( lesions, swelling, fever, and paralysis) Syndrome-group of symptoms or signs accompanying a particular disease COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health  OCCURRENCE OF A DISEASE Incidence-number of people in a population who develop a disease during a particular time period Prevalence -number of people in a population who develop a disease at a specified time, regardless of when it first appeared(old and new cases) COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health  Sporadic disease- Disease that occurs occasionally in a population at irregular intervals FREQUENCY AND Endemic disease- Disease continually DISTRIBUTION present in a population at a steady OF DISEASE level Outbreak - A slight increase in the level of disease over endemic level FREQUENCY AND DISTRIBUTION OF DISEASE Epidemic disease – disease acquired by many hosts in a given area in a short time – disease with sudden increase of morbidity (illness rate) and mortality (death rate) above the normal level Pandemic disease Worldwide epidemic EPIDEMIC OR OUTBREAK WILL ONLY OCCUR IF… the equilibrium is changed between: host- susceptibility (host or reservoir) virulence of the infectious agent- (bacteria, viruses, parasites, or fungi or their products) environment- that promotes the exposure are upset  VIRULENCE ability of an organism to infect the host and cause a disease virulence factors are molecules expressed and secreted that enable them to: colonize the host evade or inhibit the immune responses of the host enter into or out of a host cell obtain nutrition from the host COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health  VIRULENCE Virulence factors that promote bacterial colonization of the host 1. The ability to use motility and other means to contact host cells and disseminate within a host. 2. The ability to adhere to host cells and resist physical removal. 3. The ability to invade host cells. 4. The ability to compete for iron and other nutrients. 5. The ability to resist innate immune defenses such as phagocytosis and complement. 6. The ability to evade adaptive immune defenses. COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health  HERD IMMUNITY Large fraction of a population is immune to a given disease, and it is difficult for the disease to spread  SEVERITY OR DURATION OF A DISEASE Acute disease – develops rapidly but lasts only a short time;(e.g. influenza) Chronic disease -develops more slowly, and the body’s reactions may be less severe, but the disease is likely to continue or recur for long periods (e.g. Infectious mononucleosis, and hepatitis B) Subacute disease- disease that is mediate between acute and chronic (e.g. subacute sclerosing panencephalitis, Latent disease -causative agent remains inactive for a time but then becomes active to produce symptoms of the disease (e.g. Shingles) COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health  EXTENT OF HOST INVOLVEMENT Local infection -invading microorganisms are limited to a re latively small area of the body (e.g. boils and abscesses) Systemic (generalized) infection-organisms or their products are spread throughout the body by the blood or lymph (e.g.Measles) Sepsis-toxic inflammatory condition arising from the spread of microbes, especially bacteria or their toxins, from a focus of infection. COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health  EXTENT OF HOST INVOLVEMENT Septicemia-also called blood poisoning, is a systemic infection arising from the multiplication of pathogens in the blood Bacteremia Toxemia Viremia COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health  EXTENT OF HOST INVOLVEMENT Primary infection is an acute infection that causes the initial illness. Secondary infection is one caused by an opportunistic pathogen after the primary infection has weakened the body's defenses Subclinical (inapparent) infection- does not cause any noticeable illness. Poliovirus and Hepatitis A virus, for example, can be carried by people who never develop the illness COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health Predisposing factor makes the body more susceptible to a disease and may alter the course of the disease. Gender females have a higher incidence of urinary tract infections than males males have higher rates of pneumonia and meningitis Genetic background Climate and weather Inadequate nutrition COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health PREDISPOSING FACTORS Fatigue Occupation Age Pre-existing illness Environment Chemotherapy Habits Emotional Lifestyle disturbances COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health PATTERNS OF DISEASE- DEVELOPMENT OF DISEASE Stages of a Disease COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health WHERE DO YOU GET THE INFECTION?  SPREAD OF INFECTION Reservoir- source of infection living organism (animal or human) inanimate object non-living (soil and water) Carrier-harbors the organisms but no signs of illness Zoonoses-diseases that occur primarily in wild and domestic animals and can be transmitted to humans COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health SOURCES OF DISEASE For organisms to be pathogenic they require – a site to maintain their ability to infect and replicate : Reservoir The object, place or person from which organisms pass to the host is called the Source Sometimes reservoir and source are the same RESERVOIRS OF INFECTION Site in nature where microbes survive (and possibly multiply) Continual sources of infection Animals Living reservoirs - rabies, lyme disease Humans Living reservoirs – Small pox, gonorrhea Fomite –soil,water Non-living reservoirs - botulism, tetanus HUMAN SOURCE Human infections only –Small pox, gonorrhea –Measles –Typhoid fever Active carriers: acutely ill HUMAN SOURCE Convalescent carriers are recovering from a disease Healthy carriers do not show symptoms of the disease but harbor the organisms inapparent infections or latent diseases Example: Typhoid Mary ANIMAL SOURCE Zoonosis – e.g. Rabies, Leptospirosis, Japanese encephalitis INSECT SOURCE Biological vectors – Insects are the reservoir of the organisms and transmit them to humans or animals – Insects are required for at least part of the developmental cycle of the organism INSECT SOURCE Mechanical vectors – Organisms are carried on the appendages of the insect  NON -LIVING RESERVOIR Some bacteria that produce harmful toxins are indigenous to the soil – e.g. Clostridium Pathogens can be passed into water and live in fish and shell fish Food is a reservoir for agents infectious to man RESERVOIR Soil, water and food Spores can be inhaled, then germinate, multiply and produce disease WATER can be fecally contaminated Besides drinking, water borne pathogens can also enter the body through sweat glands, abraded skin etc.. FOOD Analysis must confirm the food as the source of the disease Factors that contribute to food infections are – Improper storage temperatures – poor hygiene – contaminated equipment – inadequate cooking FOMITES Inanimate objects, other than food and water e.g. Catheters, needles etc..  How are infectious microorganisms acquired?  TRANSMISSION OF DISEASES 3 major Routes 1. Contact 2. Vehicle 3. Vectors COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health  CONTACT TRANSMISSION Direct contact transmission(person-to -person transmission Indirect contact transmission - from reservoir to a susceptible host by a nonliving object(fomite) Droplet transmission -microbes are spread in droplet nuclei (mucus droplets) that travel only short distances COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health MODES OF TRANSMISSION Direct contact Respiratory Oral fecal Vertical (mother to fetus) Sexual Insect-borne MODES OF TRANSMISSION Direct – Requires close association between infected and susceptible host – Person – to – person MODES OF TRANSMISSION Direct – From person to person by close association e.g. kissing, sexual contact sneezing etc.. MODES OF TRANSMISSION Indirect – Vehicle (fomites, water) – Airborne (aerosols) – Vector MODES OF TRANSMISSION Indirect- from one person to another through intermediates such as food, dust, water or fomites VEHICLE TRANSMISSION Waterborne transmission-water contaminated with untreated or poorly treated sewage (cholera, waterborne shigellosis, and leptospirosis) Food borne transmission-transmitted in foods that are incompletely cooked, poorly refrigerated, or prepared under unsanitary conditions.( food poisoning and tapeworm infestation) Airborne transmission -spread of agents of infection by droplet nuclei in dust that t ravel more than 1 meterfrom the reservoir to the host COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health  VEHICLE TRANSMISSION Transmission of disease agents by a medium: water, food, or air Other media include blood and other body fluids, drugs, and intravenous fluids COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health  VECTOR TRANSMISSION Vectors-animals that carry pathogens from one host to another Arthropods are the most important group of disease vectors Mechanical transmission Biological transmission COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health EPIDEMIOLOGICAL VECTORS Arthropods – Invertebrates with jointed appendages – Ticks, flies, mosquitoes, fleas Plague Malaria Trypanosomiasis Lyme Disease: Tick Skin manifestation Borrelia burgdorferi EPIDEMIOLOGICAL VECTORS Mechanical vector Biological vector – Microbe proliferates in arthropod – Necessary component in the life cycle of the microbe – Sometimes transovarian transmission THE COMMUNICABLE DISEASE CYCLE Reservoir Portal of exit Transmission Disease Portal of entry PORTALS OF ENTRY AND EXIT Respiratory tract Intestinal tract Mucous Urinary tract membranes Genital tract Skin Blood How does the body fight infection? INFECTIOUS AGENTS WHICH CONFRONTS THE IMMUNE SYSTEM COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health HUMAN DEFENSES VS INFECTION Physical and Physiological Barriers Innate immunity Acquired immunity FIRST LINE OF DEFENSE AGAINST INFECTION COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health SKIN AND MUCUS MEMBRANE COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health EPITHELIAL CELLS-ENDOTHELIA COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health INFLAMMATION AND PHAGOCYTOSIS COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health COLLEGE OF PUBLIC HEALTH SEAMEO TROPMED Regional Centre for Public Health, UNIVERSITY OF THE PHILIPPINES MANILA Hospital Administration, Environmental and Occupational Health THANK YOU!