environmental health ech4102
DESCRIPTION
presentation slideTRANSCRIPT
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CHAPTER 1: PUBLIC AND
ENVIRONMENTAL HEALTH
FOR ECH4102
BY N. ABDULLAH
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LEARNING OBJECTIVE
1. To explain environmental engineering aspect in public health.
2. To identify and describe dissemination of infectious disease
related to water and other route of transmission.
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PUBLIC HEALTH CONCEPT
Important major areas of public health:
1. Health Services
2. Epidemiology
3. Social/Behavioral Science
4. Environmental Health
Deals with all environmental aspects (physical, chemical & biological) that impact human
health.
Involve assessment & control of these environmental factors to prevent disease &
improve health
5. Biostatistics
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Health Services
Deals with diagnose & treatment of diseases
Epidemiology
Study the causes of illness and distribution of disease in populations.
The science behind public health study disease control & prevention.
Social/Behavioral Science
Deals with human psychology, economics, history, and anthropology. Focus to describe, understand, predict,
and change the public's health
Biostatistics
Application of statistic in area of biology via data collection, analysis and interpretation.
applied in public health including epidemiology, health services research, nutrition, and environmental health
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PUBLIC HEALTH POLICE POWERS
1. Inspections & closures
2. Licensing & discipline of health professionals & facilities
3. Quarantine & isolation
4. Vaccination, testing and treatment requirement
5. Seizure, embargo and impounding of unsafe substances
Public Health vs. medical care:
1. Skills are very often different
2. Public Health deals with populations, prevention and policy, and
includes research on all of these.
3. Treatment of individual patients is NOT its focus, but rather
populations at risk
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MAJOR TYPES OF PUBLIC
HEALTH ACTIVITIES
1. Surveillance
2. Outbreak investigation
3. Reference diagnosis and consultation
4. Research (bench-to-field-to-prevention)
5. Technical assistance & training (lab &
epidemiology)
6. Initiate & support implementation
projects
7. Health policy and Health
communication
[Philosophically founded on Epidemiology]
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1. SURVEILLANCE
Definition:
Ongoing systematic collection,
analysis, interpretation and
dissemination of health data =
information for action.
Types of Surveillance:
1. Active
2. Passive
3. Enhances passive
4. Sentinel
6 core activities of public health
surveillance:
1. detection,
2. registration,
3. confirmation,
4. reporting,
5. analysis and
6. feedback
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1. Active surveillance: health department
visit or call a location to collect data
2. Passive surveillance: report is sent to
health department based on known rules
and regulations
3. Enhanced passive : Health Department
distribute information on a particular
disease and ask for data/report
4. Sentinel surveillance: a pre-selected
sample of potential data sources submit
information.
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1. SURVEILLANCE SYSTEM
Hospital syndromic
surveillance
Syndromes
Diagnostic tests
Bed and ventilator availability
Prescription pharmaceutical stocks/usage
School surveillance
Absenteeism
Syndromes
Reportable disease surveillance
Environmental surveillance
24/7 phone duty
Death surveillance
Pneumonia and influenza
Unusual deaths
Death certificates
OTC pharmaceutical surveillance
EMS surveillance
ELCIDS food-borne disease surveillance
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EMS = Environmental Management System/
emergency medical service
OTC = over the counter
ELCIDS = epidemiological and Laboratory
Capacity for Infectious Disease Surveillance
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Ref: WHO
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2. OUTBREAK INVESTIGATION
Definition of Outbreak:
The occurrence of more cases than is expected in a given area
over a period of time.
Types of Outbreak:
1. Common source: everyone is exposed to same thing
2. Propagated: spread gradually from a person to another
3. Mixed: common source+propagation
4. Others: zoonotic or vector-borne
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2. OUTBREAK INVESTIGATION
Work flow:
1. Prepare for field work
2. Establish the existence of an outbreak
3. Verify the diagnosis
4. Define and identify cases
1. Establish a case definition
2. Identify and count cases
5. Perform descriptive epidemiology
6. Develop hypotheses
7. Evaluate hypotheses
8. Reconsider/refine hypotheses and conduct additional studies
9. Implement control and prevention measures
10. Communicate findings
Objectives:
1. Describe the outbreak: person, place, & time
2. Determine disease characteristics
Specific agent Pathogenicity Incubation period Communicability
3. Identify modes of transmission
Person-to-person/ Airborne/ Common source (food or water)/Zoonotic/Vector-borne
4. Identify additional cases and
contacts
5. Identify the source of infection
6. Interrupt disease transmissionpresent and future.
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2. HOW TO CONTROL EPIDEMIC?
1. Insect or animal reservoir- effective control by eliminate
them.
2. Control transmission of pathogen
Food or water: water purification, pasteurised milk, food protection law
Air-borne: difficult to control, wear mask 3. Vaccination-tetanus, small pox, diphtheria, whooping
cough, polio myelitis
1. MMR vaccine (mump, measles and rubella)
2. HPV vaccine-given to young girl (prevent cervical cancer)
4. Quarantine- limit freedom of movement of infected individual
6 quarantinable diseases (international agreement) are: 1) smallpox, 2) cholera, 3) typhoid fever, 4) plague, 5) yellow fever, 6) relapsing fever.
Signal flag called
YELLOW JACK or LIMA
show ship is under
Quarantine.
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Vaccination-tetanus, small pox, diphtheria, whooping cough, polio myelitis have been eliminated.
Adult inadequately immunised against childhood disease- low titre of Antibodies as immunity gradually disappear with age., so tetanus vaccine to be given every 10yr
Two vaccines (dead polivirus & oral live-attenuated virus) have eradicated polio from most countries in the world,[3][4] and reduced the worldwide incidence from an estimated 350,000 cases in 1988 to just 223 cases in 2012
Quarantine- involve limitation of freedom of movement of individual with active infection to prevent spread of disease, yellow
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HOW VACCINE WORKS?
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WHAT IS DISEASE?
Disease (due to an infectious agent) is what may happen while your immune response tries to control
an infection;
Disease may be the final outcome if your immune system either fails, or over reacts.
Infection does not necessarily equal disease
Infectious disease: disease caused by replicating agent transmissible to human from other person,
animal or environment
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STAGES OF DISEASE
In term of clinical symptom, typical course of disease can be divided into 6
stages:
1. Infection organism lodged in host
2. Incubation period- time of infection & appearance of symptoms. Length can
be short/long depends on inoculum size, virulence of pathogen, resistance of
host and distance from entrance site to the focus infection site
3. Prodromal period-a short period where 1st symptoms such as headache and
feeling of illness appear
4. Acute period- disease at its height, with overt (done or shown openly; plainly
apparent) symptoms such as fever and chills
5. Decline period- symptom is subsiding, temperature falls, followed by intense
sweating and feeling of well-being
6. Convalescent period- patient regains strength and return to normal.
During later stage of infection cycle, immune mechanism of the host becomes
increasingly important. Recovery is normally due to these immune mechanism.
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Endemic low incidence of disease constantly present in population
Outbreak cases number sudden increase in short time
Epidemic larger cases number spread to wider area
Pandemic disease spread cross the globe
Mortality death incidence
Morbidity fatal + nonfatal cases.
Statistically more precise to tell the health of a population compare to mortality- as major cause of illness is quite
different than a major cause of death.
TERMINOLOGY
RELATED TO DISEASE
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Endemic
Disease that is constantly present in a population, usually at low incidence
Pathogen may no be highly virulent
Majority of people is immune
Though, few individual may suffer and remain reservoir for the infection
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CAUSE OF WORLDWIDE DEATH
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TOP10 CAUSE OF DEATH WORLDWIDE
Low Income
1. Lower respiratory infections
2. Diarrhoeal diseases
3. HIV/AIDS
4. Heart disease
5. Malaria
6. Stroke
7. TB
8. Premature birth
9. Birth asphyxia
10. Neonatal infection
Middle income
1. Heart attack
2. Stroke
3. Pulmonary disease
4. Lower respiratory infection
5. Diarrhoeal diseases
6. HIV/AIDS
7. Road accidents
8. TB
9. Diabetes
10. High blood
High Income
1. Heart attack
2. Stroke
3. Lung Cancer
4. Alzheimer
5. Lower Respiratory infection
6. Pneumonia
7. Colon cancer
8. Diabetes
9. High blood
10. Breast cancer
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TOP10 CAUSE OF DEATH IN
MALAYSIA (2008)-MEDICALLY CERTIFIED
1. Heart attack
2. Pneumonia
3. Cerebrovascular disease
4. Septicaemia
5. Road accident
6. Chronic respiratory disease
7. Lung cancer
8. Diabetes
9. Condition originating in the perinatal
10. Liver diseases
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NATION HEALTH BURDEN-DALY
The WHO global burden of disease (GBD) measures burden of disease using the disability-adjusted life year
(DALY).
This time-based measure combines years of life lost due to premature mortality and years of life lost due to
time lived in states of less than full health.
DALY include assessment on the burden of disease consistently across diseases, risk factors and regions.
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EMERGING INFECTIOUS DISEASES
Newly identified & previously unknown infectious agents that cause public health problems either locally or internationally
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Re-emerging infectious disease Infectious agents that have been known for some time, had fallen to such low levels that they were no longer considered public health problems & are now showing upward trends in incidence or prevalence worldwide
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EMERGING INFECTIOUS DISEASE 1.SARS
2. West Nile disease
3. Variant CJD disease
4. Monkey pox
5. Ebola and Marburg viruses
6. Dengue
7. Influenza H5/N1 (?)
8. Hanta virus
9. E. Coli O157:H7
10. Antibiotic-resistant
Pneumococci
S.aureus (MRSA)
Gonococci
Salmonella
11. Cryptosporidium
12. Anthrax
13.Spanish flu
14. Dengue & DHF
Factor contribute the emergence of EID: AGENT
1) Evolution of pathogenic infectious agents (microbial adaptation & change)
2) Development of resistance to drugs 3) Resistance of vectors to pesticides
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EMERGING INFECTIOUS DISEASE
(AIDS-RELATED)
1. Pneumocystis carinii
pneumonia
2. Tuberculosis
3. Mycobacterium-avium
complex
4. Kaposis sarcoma (HHV-8)
5. HSV-2
6. Cryptosporidium
7. Microsporidium
8. Cryptococcus neoformans
9. Penicillium marneffei
10. Disseminated salmonella
11. Bacillary angiomatosis
(Bartonella henselae)
12. HPV
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ANIMAL-HUMAN EID
>2/3rd emerging infections originate from animals- wild & domestic
Emerging Influenza infections in Humans associated with Geese, Chickens & Pigs
Animal displacement in search of food after deforestation/ climate change (Lassa fever)
Humans themselves penetrate/ modify unpopulated regions- come closer to animal reservoirs/ vectors (Yellow fever,
Malaria)
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FACTORS CONTRIBUTING TO EMERGENCE
AGENT
Evolution of pathogenic infectious agents
(microbial adaptation & change)
Development of resistance to drugs
Resistance of vectors to pesticides
Note : Increasing virulence of microbes like Influenza A virus, which exhibits frequent changes in its antigenic structure giving rise to new strains with endemic and pandemic propensities.
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FACTORS CONTRIBUTING TO EMERGENCE
HOST
Human demographic change (inhabiting new areas)
Human behaviour (sexual & drug use)
Human susceptibility to infection (Immunosuppression)
Poverty & social inequality
Aging of population
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HOST FACTORS CONTRIBUTING TO EMERGENCE ARE:
1.Mass migration of people provoked by natural and man made disaster with concomitant rehabilitation of displaced people in temporary human settlements under unhygienic conditions.
2.Uninhibited and reckless industrialization leading to migration of labor population from rural to urban areas in unhygienic squatter settlements
3.International travel as a result of trade and tourism contributing to global dispersion of disease agents, disease reservoirs and vectors
4.Changes in lifestyle that promote unhealthy and risk prone behavior patterns affecting food habits and sexual practices.
5.Declining immunity of as a result of HIV infection, which make him vulnerable to a host of infections.
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FACTORS CONTRIBUTING TO EMERGENCE
ENVIRONMENT
Climate & changing ecosystems
Economic development & Land use (urbanization, deforestation)
Technology & industry (food processing & handling)
International travel & commerce
Breakdown of public health measure (war, unrest, overcrowding)
Deterioration in surveillance systems (lack of political will)
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Environmental sanitation characterized by unsafe water supply , improper disposal of solid and liquid waste, poor hygienic practices and congested living conditions all contribute to emergence of infection.
Climatic changes resulting from global warming inducing increased surface water evaporation , greater rainfall changes in the direction of bird migration and changes in the habitat of disease vectors are also contributory factors.
Deforestation forces animals into closer human contact- increased possibility for agents to breach species barrier between animals & humans
El Nino- Triggers natural disasters & related outbreaks of infectious diseases (Malaria, Cholera)
Global warming- spread of Malaria, Dengue, Leishmaniasis, Filariasis
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EXAMPLES OF RECENT EMERGING DISEASES
Source: NATURE; Vol 430; July 2004; www.nature.com/nature
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Dr. KANUPRIYA CHATURVEDI
EXAMPLES OF EMERGING INFECTIOUS DISEASES
Hepatitis C- First identified in 1989
In mid 1990s estimated global prevalence 3%
Hepatitis B- Identified several decades earlier
Upward trend in all countries Prevalence >90% in high-risk population
Zoonoses- 1,415 microbes are infectious for human
Of these, 868 (61%) considered zoonotic 70% of newly recognized pathogens are zoonoses Notes : Zoonoses process whereby an infectious disease is transmitted between different species of animals
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EMERGING ZOONOSES: HUMAN-ANIMAL INTERFACE
Marburg virus Ebola virus
Bats: Nipah virus Avian influenza virus
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EMERGING ZOONOSES: HUMAN-ANIMAL INTERFACE
Hantavirus Pulmonary Syndrome
Borrelia burgdorferi: Lyme
Deer tick (Ixodes scapularis)
Mostomys rodent: Lassa fever
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DISEASE
CLINICAN VIEW
classified according to signs and symptoms
1. Diarrheal diseases
2. Respiratory diseases
3. Cutaneous/soft tissue infection
4. CNS diseases
5. Septicemic diseases
6. Fever of undetermined origin
EPIDEMIOLOGIST VIEW
Mean of spread of infectious diseases
1. Contact
Direct
Indirect formites, body secretions
2. Vector
3. Air-borne
4. Food-borne
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CAUSATIVE AGENTS OF DISEASE
1. biological- bacteria , virus, protozoa, helminth (virus) and fungi, prion
2. chemical- pesticide, petroleum product, cleansing agent
3. physical- sun UV, X-ray equipment,
4. too little of something- lack of Vit. D cause rickets, lack of niacin cause kwashiorkor
5. too much of something- excessive food or water can be fatal, excess CO2 in respiratory can cause fatal
6. hereditary- haemophilia, baldness, poor eyesight
7. stress-emotional disorder, stroke, heart attack
8. disease of unknown cause- many die due to environmental pollutant working synergistically with other factors. Eg. cancer
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CAUSATIVE AGENTS OF DISEASE
Biological, Chemical and Physical cause of disease
are spread through air, water, food, insect, fomites
(fork, doorknob etc) and animal.
In Environmental health, many programmes
address the need to control the causative agent
while it is in the environment before it get into the
public and cause disease
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SOME IMPORTANT DISEASES
1. Spread by Contact
STD
Staphylococcus infections
Streptococcal infections
Nosocomial
Rhinovirus colds
Brucellosis (slaughter house contact)
Hepatitis B
2. Vector-borne
Malaria, dengue, yellow fever
Viral encephalitis
Schistosomiasis
Leishmaniasis
Trypanosomiasis
Tularemia
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SOME IMPORTANT DISEASES
3. Air-borne
Tuberculosis
Influenza
Childhood infections (measles, mumps, rubella, pertussis)
Legionella
4. Food- & Waterborne
Cholera
Giardiasis
Listeriosis
Staphylococcal enterotoxin food poisoing
Shigellosis
Campylobacter
Salmonellosis
Clostridium perfringens food poisoning
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1. TYPES OF TRANSMISSIONS BY
CONTACT 1) Direct Host-to-host
infected host transmit disease to a
susceptible host
route can be respiratory (cold, flu),
direct contact
(syphilis, gonorrhea),
skin direct contact
(staphyloccus causes
boil, pimples) or fungi
(ringworm)
2) Indirect host-to-host
occur by living/ inanimate means
living agent transmit disease is called vector- usually anthropods (insect, mites or fleas) or
vertebrates (dog, cats)
Anthropods only carrier of agent from 1 host to another , not a host for the disease- via biting
Some pathogen replicate inside anthropods (this consider an alternate host) and build up
inoculum
Inanimate agent (fomites)- bedding, toys, books, surgical equipment- which come in contact with
people can also transmit disease.
Food and water are referred to as disease vehicles.
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ASSESSING INFECTIOUS DISEASE
TRANSMISSION
Epidemiologist follows the incidence of disease by correlate geographical, seasonal and age-group distribution of a disease with possible modes of transmission.
If disease is limited to a restricted geographical location- it may suggest vector, eg. Tropical region, malaria via mosquito vector
If disease is limited by seasonal- often indicate mode of transmission eg. Measles, chickenpox for school children and close contact
Age distribution- important for statistic to eliminate particular routes of transmission
Different pathogen, have different mode of transmission- usually related to the habitat of the organism in the body
Eg. Respiratory pathogen is usually airborne, intestinal pathogen usually, waterborne/ food borne
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PARASITOLOGY VOCABULARY
Host: The animal the parasite lives on/in
There can be more than one host during a life cycle
Often life cycle include larval stages and adult stages in different hosts
Vector: an animal that carries a parasite to the host
Reservoir: Non-human host where the parasite can live
This term is only applied when the parasite can infect humans
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DISEASE RESERVOIR
1) Human
AIDS
Syphilis
Gonorrhea
Shigellosis
Typhoid fever
Hepatitis B
Herpes Simplex virus
2) Animal (zoonoses)
Anthrax
Listeriosis
Viral encephalitis
Rabies
Plaque
Brucellosis
Non-typhoidal salmonellosis
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DISEASE RESERVOIR
3) Soil
Botulism
Tetanus
Blastomycosis
Coccidioidomycosis
Histoplasmosis
4) Water
Legionnaires disease
Meliodosis
Pseudomonas infections- sepsis, UTI, hot tub folliculitis
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CARRIERS
infected individual not showing obvious sign of clinical disease.
Potential cause of infection to others
Acute carrier- individual in the incubation period of disease, then follow by development of the infection
Chronic carrier-individual who had a clinical disease and recovered, or may have subclinical infection that remained in apparent throughout.
Identify carrier by X-ray, immune test, cultural
2 diseases with significant carrier- typhoid fever and TB (usually food handler) eg. Typhoid Mary in early 1990s
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EPIDEMIOLOGICAL PROPERTIES
OF INFECTIOUS AGENTS
1. Infectivity
The propensity for transmission
Measured by 2o attack rate in household, school, etc
2. Pathogenicity
The propensity for an agent to cause disease or clinical symptoms
Measured by the ratio of apparent: inapparent
3. Virulence
The propensity for an agent to cause severe disease
Measured by the case:fatality ratio
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EPIDEMIOLOGICAL TERMINOLOGY
OF INFECTIONS
Incubation Period
Secondary attack rate
Persistent infection
Latent infection
Inapparent (subclinical infection)
Immunity
Herd immunity
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Incubation period - The period between exposure to the agent and onset of infection (with symptoms or signs of infection)
Secondary attack rates - The rates of infection among exposed susceptibles after exposure to an index case, such as in a
household or school
Persistent infection - A chronic infection with continued low-grade survival and multiplication of the agent
Latent infection - An infection with no active multiplication of the agent, as when viral nucleic acid is integrated into the nucleus of a
cell as a provirus. In contrast to a persistent infection, only the
genetic message is present in the host, not viable organisms.
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Inapparent (or subclinical infection) An infection with no clinical symptoms, usually diagnosed by serological
(antibody) response or culture
Immunity The capacity of a person when exposed to an infectious agent to remain free of infection or clinical illness
Herd immunity
The immunity of a group or community. The resistance of
a group to invasion and spread of an infectious agent, based
upon the resistance to infection of a high proportion of
individual members of the group.
The resistance is a product of the number of susceptible
and the probability that those who are susceptible will come
into contact with an infected person.
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PORTAL OF ENTRY
1. Skin- epidermis provide defence vs. pathogen
entry, if cut occur, pathogen may allow in
2. reproductive organ- penis, uterus and ovaries
require body contact, STD- prevention by prophylactics or abstention from sex
3. respiratory tract (nose, bronchi, aveoli)- TB,
pneumonia, strep, human nose has hair to
filter pathogen, cilia, mucus to prevent it
4. Digestive tract- mouth, aesophagus,
stomach, small intestine and large intestine-
HCL secreted in stomach kill some germ, bile
has an antiseptic power because eof its high
pH
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HUMAN DEFENCE AGAINST DISEASE
1st line of defence (ENVIRONMENTAL MANAGEMENT)- prevention. Apply technology and art of science to control causative agent of disease in environment before it gets to human. This use the environmental health element
2nd line of defence (PUBLIC HEALTH & PREVENTIVE MEDICINE)-based on human body adaptation to prevent agent of disease. This include skin, mucous membrane, cilia, tears- so, proper nutrition, good personal health practise, routine check up
3rd line of defence (PUBLIC HEALTH &PREVENTION MEDICINE)-if the 2nd defence are not sufficient to prevent the entrance of pathogens, then use immunity (active and passive) and phagocytosis (natural- leukocytes destroy pathogen in blood).
4th line of defence (CURATIVE MEDICINE)- when sick, need surgery-medication.
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THE 1ST LINE OF DEFENCE VS.
DISEASE Water quality management
Human waste disposal
Solid and hazardous waste management
Rodent control
Insect control
Milk sanitation
Food quality management
Occupational health practice assure healthy and safety of worker
International travel sanitation
Air pollution control
Water pollution control
Environment safety & accident prevention
Noise control
Housing hygiene
Radiological health control
Recreational sanitation
Institutional environmental management- prevent nosocomial
infection
Land use management
Product safety & consumer protection
Environmental planning
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2nd LINE of DEFENCE vs.
DISEASE: Host defenses: physical, chemical, anatomical barriers:
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3rd LINE OF DEFENCE:
nonspecific defenses (passive defenses; innate immunity) respond to any invader natural barriers, antimicrobial compounds phagocytes (neutrophils or polymorphonuclear leukocytes, PMNs) complement natural killer cells (NK cells)
specific defenses (adaptive immunity) respond to a specific invader cell-mediated cytotoxic T cells, activated macrophages humoral - antibodies
cytokines, chemokines small proteins; coordinate, modulate
Host immunity: the ability of higher organisms to resist infection
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blood and lymph systems
extravascation:
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extravascation:
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bacteria
phagocytosis:
PMN
nucleus
lysosome
bacteria are engulfed
in phagosome of PMN
phagosome fusion of
phagosome
and lysosome
degradation of
bacteria within
phagolysosome release of bacterial
fragments to external
environment
several pattern recognition molecules (PRMs) on PMN membrane (aka Toll-like receptors (TLRs))
recognize a pathogen-associated molecular pattern (PAMP)
e.g., TLR-4 recognizes bacterial LPS
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Innate host defenses:
natural host resistance some organisms more sensitive to infection by given pathogen than others
age very young, very old individuals are most susceptible
stress fatigue, exercise, dehydration, large climate changes, stress-related hormone release, suppression of inflammation; predispose to infection
diet alteration may influence normal microbiota, decrease resistance, alter susceptibility
physical, chemical, anatomical barriers may prevent successful infection when integrity is intact
tissue specificity pathogen must contact environment suited to its needs, for successful infection
compromised host: one or more resistance mechanisms inactive;
susceptibility increased
suppressed e.g., drug therapy-induced versus compromised e.g., AIDS
3rd LINE OF DEFENCE (continue)
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ZOONOSES
disease that occur primarily in animal, but occasionally transmitted to human.
Since public health for animal is less, infection rate for these disease in animal is very high.
to control zoonosis in human is not good approach to eradicate it from animal reservoir.
Success case for zoonosis control are bovine TB and brucellosis via pasteurization of milk.
Some have more complex life cycle. Eg. Protozoa (malaria) and metazoans(tapeworms). So, control in human or in the alternative
animal host.
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NOSOCOMIAL INFECTION
Hospital acquired infections Cross infection from patient or hospital personnel and vice versa
present a constant hazard
Hospital are hazardous because
1. many patients are weakened resistance to disease
2. reservoir for highly virulent pathogen
3. Crowding of wards
4. much movement of hospital personnel from patient to patient
5. hospital procedure such as catheterisation, hypodermic injection, spinal puncture, removal of tissue/fluid/biopsy carry risk of introducing pathogen to patient
6. In maternity ward, infant immune system usually susceptible to infection
7. surgical procedure is major hazard, body exposed to source of contamination
8. drug for immunosuppressant (organ transplant patient) increase susceptibility to infection
9. use antibiotic to control infection carry risk of resistant strain (MRSA)
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HOSPITAL PATHOGEN
E.coli as most causes for Urinary tract infection, others are yeast Candida albican, Psedomonas aeruginosa,
enterococcus
Staphylococcus aureus - associated with skin, surgical, and lower respiratory tract- problem for newborn baby
S.aureus habitat is in nasal passage as normal flora. So, in healthy personnel show no disease, but once infected the
susceptible patients may cause serious infection
Pseudomonas aeruginosa- causing infection of lower respiratory and urinary tract. Also cause infection in burn
patients (where patient loss barrier to skin infection) It is drug
resistant, so difficult to treat.
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WHAT ARE THE
SCARIEST INFECTIOUS THREATS? Bioterrorism (anthrax; smpox; etc.
Pandemics (influenza; plague;..)
Can you say: BIRD FLU ???
Nosocomial
Infections
Ebola; SARS;
Lyme; Hanta;
Cryptosp;
Cyclospora;
E. coli 0157/H7
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Mass Casualty =
Bioterrorism; Pandemics
New Infectious Agents =
Nipah virus; Pulmonary Hantavirus
Syndrome; Cyclospora;
Antimicrobial Resistance =
Bacterial, Fungal, Viral, Parasitic
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POSSIBLE AGENTS OF BIOTERRORISM
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Category A: (anthrax, botulism, plague, smallpox, tularemia,
VHFs)
can be easily disseminated or transmitted from person to person;
result in high mortality rates and have the potential for major public health impact;
might cause public panic and social disruption; and
require special action for public health preparedness
POSSIBLE AGENTS OF BIOTERRORISM
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POTENTIAL BIOTERRORISM AGENTS
Category B: (ricin, food/water threats, brucellosis, Q fever, etc.)
are moderately easy to disseminate;
result in moderate morbidity rates and low mortality rates; and
require specific enhancements of CDC's diagnostic capacity and enhanced disease surveillance.
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POTENTIAL BIOTERRORISM AGENTS
Category C: (emerging infections like Nipah virus and hantavirus)
availability;
ease of production and dissemination; and
potential for high morbidity and mortality rates and major health impact.
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CHARACTERISTICS OF
BIOTERRORISM
Presentation of a rare and serious disease
Presentation of rare and serious symptoms
Large number of people seeking care for nonspecific symptoms
Unexpected rapidly increasing disease incidence
Disease clusters w/a common source of infection
Endemic disease rapidly emerging at an uncharacteristic time or in an unusual pattern
Low attack rates for people who stay indoors
Sudden increase in mortality
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BIOLOGICAL AND CHEMICAL
WARFARE
threat to human population,
An emerging challenge for public health
Silent, invisible and deadly
Use to injure, kill and incapicitate
Chemical warfare: gas or liquid form
Biological warfare: living bacteria (B.anthracis-anthrax) or viruses (variolae- small pox)
Use in terrorism act
Chemical warfare: will be discussed in Chapter 7 (sub-section).
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CHALLENGE ON DECISION MAKING
Infectious diseases: Some are global, Some are geographically focal, Some are economically important & Some are socially important
Whether to Eradicate or Eliminate or control? Depends on:
Ability of available tools (vaccines, drugs, etc.)
Epidemiologic vulnerability: ability to implement available tools in a cost-effective manner. Based on the LIFE CYCLE
Availability of sustained funding.
Political will:
Burden of disease Perception and promotion of outcome Impact on over all health services sector Impact on over all development Luck
-
CHALLENGES TO UNDERSTAND &
CONTROL PARASITIC DISEASE
BROAD SCIENTIFIC CHALLENGES
Vaccine development Vector manipulation Drug development Drug resistance Host genetic contribution Rapid surveillance/diagnostic tools Few new scientists entering the field
BROADER SOCIETAL CHALLENGES
Universal Sanitation/Public Health Adequate Housing Adequate Food - nutrition Available Health Care Sustainability (Public/Private/Political Commitment) Few new public health officials entering the field
-
SOME OF THE REAL CHALLENGES OF
PARASITIC HELMINTH E/E/C CAMPAIGNS
Implementation i.e, Just Doing It
Donor fatigue it takes a long, sustained effort
Drug resistance the threat of any drug- based anti-infectious disease program - especially with a single drug
Monitoring ??
Research ??
See example: Dracunculiasis
-
TASK TO DEAL WITH EMERGING
DISEASES
Surveillance at national, regional, global level
epidemiological, laboratory ecological anthropological
Investigation and early control measures
Implement prevention measures
behavioural, political, environmental
Monitoring, evaluation
-
CURRENT SCENARIO OF
SURVEILLANCE SYSTEM
Independent vertical control programmes
Surveillance gaps for important diseases
Limited capacity in field epidemiology, laboratory diagnostic testing, rapid field investigations
Inappropriate case definitions
Delays in reporting, poor analysis of data and information at all levels
No feedback to periphery
Insufficient preparedness to control epidemics
No evaluation
-
Dr. KANUPRIYA CHATURVEDI
SOLUTIONS
Public health surveillance & response systems
Rapidly detect unusual, unexpected, unexplained disease patterns
Track & exchange information in real time
Response effort that can quickly become global
Contain transmission swiftly & decisively
-
Dr. KANUPRIYA CHATURVEDI
SOLUTION: GOARN PROGRAMME
Global Outbreak Alert & Response Network
Coordinated by WHO
Mechanism for combating international disease outbreaks
Ensure rapid deployment of technical assistance, contribute to long-term epidemic preparedness & capacity building
-
Dr. KANUPRIYA CHATURVEDI
SOLUTION: GOARN PROGRAMME The Global Outbreak Alert and Response Network (GOARN) is a technical collaboration of existing institutions and networks who pool human and technical resources for the rapid identification, confirmation and response to outbreaks of international importance. The Network provides an operational framework to link this expertise and skill to keep the international community constantly alert to the threat of outbreaks and ready to respond.
The Global Outbreak Alert and Response Network contributes towards global health security by:
combating the international spread of outbreaks
ensuring that appropriate technical assistance reaches affected states rapidly
contributing to long-term epidemic preparedness and capacity building.
-
SOLUTIONS Internet-based information technologies
Improve disease reporting
Facilitate emergency communications &
Dissemination of information
Human Genome Project
Role of human genetics in disease susceptibility, progression & host response
Microbial genetics
Methods for disease detection, control & prevention
Improved diagnostic techniques & new vaccines
Geographic Imaging Systems
Monitor environmental changes that influence disease emergence & transmission
-
KEY TASKS - CARRIED OUT BY WHOM?
National
Regional
Global
Synergy
-
WHAT SKILLS ARE NEEDED?
Multiple expertise needed !
Infectious
diseases
Epidemio-
logy
Public Health
International
field experience Information
management
Laboratory
Telecom. &
Informatics
-
GLOBAL DISEASE INTELLIGENCE:
A WORLD ON THE ALERT
Collection
Verification Distribution
Response
-
THE BEST DEFENSE (MULTI-FACTORIAL)
Coordinated, well-prepared, well-equipped PH systems
Partnerships- clinicians, laboratories & PH agencies
Improved methods for detection & surveillance
Effective preventive & therapeutic technologies
Strengthened response capacity
Political commitment & adequate resources to address underlying socio-economic factors
International collaboration & communication
-
END PART 1
-
PARASITIC DISEASES
-
PATHOGENS CATEGORY CAUSING
DISEASE
1. Virus
2. Bacteria
3. Fungi
4. Parasites
-
PATHOGENS CATEGORY CAUSING DISEASE Dissemination of fungi in the body indicates a breach or deficiency of host defenses.
Superficial fungal infection: on cutaneous skin, hair, no discomfort to patient, eg tinea vigra, tinea visicolor
Cutaneous fungal infection: dermatophyte, ringworms-most fungal infection in human
Subcutaneous mycoses: deeper layer of epidermis
Systemic mycoses: eg in lung, can be life threatening
Biphasic or dimorphic: can exist as mold/hyphal/filamentous form[1] or as yeast.
Prion: is PrP is an infectious agent composed of protein in a misfolded form
Some fungi, eg yeast Candida spp. can be found on skin rich in subaceous gland (eg: mouth, vagina). Found in healthy tissue, but sometimes under certain condition can cause disease
-
MAJOR GROUPS OF PARASITES
1. Protozoans Single-cell eukaryotes Eg: Malaria, Giardia, Trichomonas vaginalis Can invade:
Tissues- Trypanosomes, Toxoplasma, Plasmodium Intestinal lumen- Entamoeba histolytica, cryptosporidium
2. Helminths (The Worms)
Multicellular animals Flukes, Tapeworms, Roundworms
3. Ectoparasites
Multicellular animals Live outside the host Ticks, Lice, Flea
-
PROTOZOA: TRYPANOSOMA CRUZI
Causing Chagas disease
Epidemiology:
Mexico to S. America 16-18 million people infected (45,000 die/yr)
Vector: Reduviid bug (aka. kissing bug)
Reservoir: rodents, dogs, cats, armadillos,
Pathologies:
Inflammation at bite Swelling of the eyes Fever, malaise Enlarged Heart Heart Failure
-
PROTOZOA: MALARIA See example for challenge to control and eradicate section.
-
PROTOZOA: ENTAMOEBA HISTOLYTICA
Epidemiology:
Worldwide distribution- Mexico, India, West and South Africa, South America
10% of the worlds population is infected (50 million)
Most are asymptomatic (carriers)
50-100,000 deaths per year
Vector: Flies carry cysts from human feces to human food or water or humans self-infect after touching fecally contaminated items, can be sexually transmitted
-
PROTOZOA: ENTAMOEBA HISTOLYTICA
Reservoir: Humans are the only hosts
Pathologies:
Mild to severe intestinal discomfort
Dysentary (bloody diarrhea)
Can invade and destroy the liver (abscess)
Treated with Metronidazole (flagyl)
-
HELMINTHS (THE WORMS) Three main groups:
1. Flukes- Liver flukes, Lung flukes, Intestinal flukes, Schistosoma
species (blood flukes)
2. Roundworms-
Intestinal (Pinworm, Whipworm, Ascarids, hookworms)
Tissue (Trichinella, Anisakis, Baylisascaris)
3. Tapeworms-
Intestinal (Teania solium-beef tapeworm)
Tissue (Echinichoccus granulosus)
-
HELMINTHS : PIN WORM
Enterobius vermicularis (Pin Worm)
Epidemiology:
Worldwide
Most common helminth in North America
No vector
No reservoir
Treatment: Mebendazole
-
HELMINTHS : ASCARIS LUMBRICOIDES
Giant Roundworm of Humans
Epidemiology:
Temperate/tropical regions with poor hygiene
2 billion (~1/3 of world pop.)
Fecal-oral transmission (eggs)
No vector, No reservoir
Night-soil
Pathologies:
Adults (12-20cm) in intestine can cause mechanical obstruction
Abdominal pain
Bowel perforation
Cough & wheezing from juveniles in lungs
Treated with Mebendazole
-
HELMINTHS : ASCARIS LUMBRICOIDES
-
HELMINTHS : FASCIOLOPSIS BUSKI
(INTESTINAL FLUKE)
Epidemiology: Southeast Asia
Females (2-7cm) produce about 25,000 eggs/day.
no vector, but has 3 hosts
Abdominal pain, diarrhea, malabsorption, toxemia
Attaches to mucosa
Reservoir: Pigs
Treatment: Praziquantel
-
HELMINTHS : FASCIOLOPSIS BUSKI (INTESTINAL FLUKE)
-
HELMINTHS: ECHINOCHOCCUS
GRANULOSUS
(Hydatid Cyst Disease)
Epidemiology: S. America, Australia, Kenya, Europe,
Russia- (where dogs are used for herding sheep)
Canine tapeworm (dogs, wolves, coyotes)
No vector
Reservoirs: Sheep, elk, caribou
Pathologies: cysts can infect liver, lungs or spleen.
Pathologies depend on location of the cyst Jaundice, coughing etc
If ruptured, the cyst fluid will typically kill the host
-
HELMINTHS: ECHINOCHOCCUS GRANULOSUS
-
3) ECTOPARASITES
Insect, mites (scabies), lice, pubic louse
(crab), head louse.
Epidemiology: Worldwide
Usually no vector
Usually temporary
Reservoirs: variable
Pathologies: Itching, scabs at the site of the bite, rashes, redness etc.
Often carriers of bacterial infections
-
PUBLIC HEALTH CONCERN:
EXAMPLES OF PARASITIC CASES
1) Drancunculiasis
2) Malaria
-
Guinea worm being removed in Zabzugu-Tatale, Ghana; 2000
1) Dracunculiasis
-
Dracunculus medinensis (Guinea worm)
-
PROGRESS IN THE ERADICATION OF DRACUNCULIASIS
1981 -- > 4,000,000 cases
1986 -- 3,500,000 cases
1989 -- 890,000 cases
1992 -- 374,000 cases
1995 -- 129,000 cases
1998 -- 79,000 cases (61%, Sudan)
1999 80,000 cases (70%, Sudan)
2000 -- 70,000 cases (73%, Sudan)
2001 -- 60,000 cases (78%, Sudan)
2002 -- 50,000 cases (74%, Sudan)
2003 -- 31,000 cases (62%, Sudan; 27%, Ghana)
2004 -- 16,026 cases (45%, Sudan; 45%, Ghana)
2005 -- 10,715 cases vs. 14,418 in 2004 (Jan-Oct)(61%, Sudan; 29%, Ghana)
[Down from 20 to 4 countries; Chad, Ethopia, Mali & South Sudan, 2012 only 542 cases]
-
DRACUNCULIASIS ERADICATION
Coordinating Programs:
WHO; UNICEF; Peace Corps; World Bank; NGOs;NHDI
Global 2000/Carter Center; B&M Gates Fdn ($28.5M)
WHO Collaborating Center (CDC)
Industrial partners
Critical Elements:
Safe water: Borehole or scoop wells; Rx source water (temephos); Filter water (nylon nets; PVC pipe filters)
Community-level health education
Case Containment, plus rewards
Regional/Country/Local (village level) commitment
Monthly reporting and feedback
Coordination and financing
-
WHAT ARE THE MAJOR CHALLENGES
TO GUINEA WORM ERADICATION?
It requires behaviour change !!!
People need to stay out of the water when they have lesions
People need to filter their water through nylon nets
In part this depends on knowledge and alternatives, but not
entirely
Other aspects are organizational, financial, technical and political
-
CHALLENGE OF ANTIMICROBIAL
RESISTANCE
Example: Malaria
~2.5 Billion (40% Worlds Population) At Risk
400-900 million febrile infections/year
0.7-2.7 million deaths/year, >75% African children
~4 die per minute ~5000 die per day ~35,000 die per week
< 20% come to attention of the health system
Pregnant women at high risk of dying, low birth weight children
Children suffer cognitive damage and anemia
Families spend up to 25% of income on treatment
Major Impediment to Economic Growth and Development, as well as health
-
2) MALARIA
-
Is malaria an emerging disease? YES !!! [At least drug-resistant malaria is an emerging disaster]
-
1940
Chloroquine
16 years
Fansidar
6 years
Mefloquine
4 years
Atovaquone
6 months
1950 1960 1970 1980 1990
DEVELOPMENT OF RESISTANCE TO
ANTIMALARIAL DRUGS
-
CHALLENGE OF ANTIMICROBIAL
RESISTANCE
SOLUTIONS..
Reduce infections (hand washing, vaccines, etc.)
Judicious (done with good judgement or sense) use of antibiotics (not every ear ache)
Limit human antibiotic use in animals
Combination therapy
Target virulence factors
Competitive exclusion
-
Malaria Prevention
Mosquito Avoidance - Evening and night behaviour - Mosquito Nets - Air conditioning - Screens - Repellant - Pyrethrin coils Mosquito Killing - Destroy breeding sites - Fog spraying - Residual spraying Plasmodium killing - Chemoprophylaxis
-
WATER-RELATED INFECTIONS
-
WATER RELATED
INFECTIONS
Related to water or impurities in water
Transmission by 4 mechanism :
1) Water- borne
2) Water-washed
3) Water-based
4) Insect vector
-
1. WATER-BORNED MECHANISM Pathogen in water taken by human/animal
Disease eg. Cholera, typhoid, diarrhoeas and dysenteries
These disease also can be transmitted by any route which allow faecal-
mouth contact
Preventive strategy- improve drink water quality, prevent casual used of
unimproved sources
cholera patient showing evidence of extensive fluid loss (hand, cheeks)
(CDC Public Health Image Library)
-
2.WATER-WASHED
MECHANISM
Infections of intestinal tract and skin
Poor hygiene and limited availability of water
3 types:
Infection of intestinal tract diarrhoeal, cholera, dysentery
Infection of skin and eyes-skin sepsis, scabies and fungal infection due to poor hygiene
Infection due to lice and mites
Prevention-increase water quality, improve
accessibility and reliability of domestic water supply,
improve hygiene
-
3.WATER BASED
MECHANISM
Pathogen spends a part of its life cycle in a water snail or other aquatic animal
Infection of parasitic worms (helmiths)
Eg: Guinea worm, larvae escape man through blister and into small aquatic animal, then man drink
water containing these larvae
Acquire by eating insufficiently cooked fish
Prevention: reduce contact with infected water, control snail population
-
4. INSECT VECTOR MECHANISM
Spread by insect which either
breed in water or bite near water
Eg. Malaria, yellow fever,
dengue, river blindness and
sleeping sickness
Prevention-improve surface
water management, destroy
breeding sites, decrease visit to
breeding sites, use mosquito
netting
-
EXCRETA-RELATED
INFECTIONS
All disease in the faecal-oral route, most water-based diseases are caused by pathogen transmitted in human excreta (normally in
faeces)
This can be controlled by improvement of water supply and hygiene, excreta disposal, toilet, final disposal or re-use
-
A). FAECAL-ORAL DISEASE (NON-
BACTERIAL)
Cause by virus, protozoa and helmiths
Spread easily from person due to bad hygiene
Improve excreta disposal unlikely to reduce their incidence. Health
education
b). Faecal-oral disease (Bacterial)
Person-to-person transmitted,
Also contaminated food crops, water source with faecal material
Eg. Salmonella passed in the faces of bird
-
C). SOIL-TRANSMITTED
HELMITHS Parasitic worms whose eggs are
passed in faeces
This route require period of development in favourable of their growth- usually moist soil
Reach to human via ingestion
Latrine help to avoid faecal contamination of the floor hep to limit transmission
Eggs survive for months between host
Eliminate eggs by sedimentation in stabilisation ponds, heat or prolonged storage
-
D). BEEF AND PORK TAPEWORMS
(TAENIA)
Require period in body of host before infecting human
When meat eaten without sufficient cooking
Prevent untreated excreta eaten by pig/cattle help
prevent transmission of
parasite
-
E). WATER-BASED HELMINTHS
Passed in excreta and then to snail (aquatic host)
Re-infect man through skin or eating uncooked fish
One egg can multiply in snail to produce thousand larvae
-
F). EXCRETA-RELATED
INSECT VECTORS
2 kinds:
1.Culex pipens group of mosquitoes, breed in highly polluted water and
transmits filariasis
2. Flies and cockroaches, breed where faeces exposed, they carry
pathogen on their bodies and intestinal tract.
-
REFUSE-RELATED
INFECTION
Poor refuse disposal encourage fly breeding
Promote disease associated with rats, such as plague, salmonellosis, endemic typhus
Uncollected refuse can obstruct streets and drainage channel
Refuse is potential source for composting, food source of animal
-
HOUSE-RELATED
INFECTION
Interaction between housing and human health are numerous
Location affect the health of inhabitant
In manner promote airborne disease- overcrowding, ventilation, air, temp, humidity
In manner promote population of rats, fleas, mites, lice- share with animals, poultry, pets.
-
WATER RELATED
DISEASES-EXAMPLES
-
transmitted almost exclusively via contaminated water (fecal-oral route); also raw shellfish, vegetables (Americas)
7 or 8 world-wide pandemics since 1817 endemic in Africa, parts of Asia, Indian subcontinent, Central & South America controlled by applying appropriate water treatment, sanitation measures
V. cholerae: gram negative, curved rod; free-living in coastal waters, adhering to
normal microbiota
disease: initiated when ingested bacteria attach to epithelial cells of small
intestine, begin to grow and release enterotoxin (toxin affecting GI tract)
characterized by copious watery diarrhea rice water stools fluid losses may exceed 20 L per day untreated, mortality rate can reach 60%
treatment: intravenous or oral liquid and electrolyte replacement therapy
(20 g glucose, 4.2 g NaCl, 4.0 g NaHCO3, 1.8 g KCl in 1 L H2O)
EXAMPLE 1 : CHOLERA
-
EXAMPLE 2: Typhoid (Salmonella typhi)
most common route of transmission is via water; may also be foodborne, by direct contact with infected individuals
virtually eliminated in developed countries as a result of water treatment practices
carrier state can be important (carrier: individual that harbours organism but shows no disease symptoms)
story of Typhoid Mary see p. 823 (11th ed) or p. 853 (10th ed) of Madigan
S. typhi: gram negative rod, one of the Enterobacteriaceae
disease: systemic infection with sustained bacteremia (bacteria in blood),
characterized by high fever (several weeks)
also initial headache, often constipation, then diarrhea complications may include perforation of intestinal wall mortality may approach 15% in untreated typhoid; reduced to less than 1% with antibiotic therapy (e.g., chloramphenicol, ampicillin, cephalosporins)
-
Example 3: Legionellosis (Legionella pneumophila)
severity of infection varies:
may be asymptomatic Pontiac fever: mild cough, mild sore throat, mild headache, self-limiting Legionellosis: a type of pneumonia, more likely to affect elderly, immune-
impaired, associated with certain L. pneumophila serotypes
intestinal disorder. then high fever, chills, muscle aches, followed by dry cough, chest and abdominal pain
Legionella: discovered in late 1970s, probably a recent human pathogen
present in small numbers in natural waters and soil, may live inside free-living protozoa, heat- and chlorine-resistant
lives happily in cooling towers, air conditioning systems, hot water tanks, whirlpool spas, etc.
bacteria disseminated in humidified aerosols, human infection is via airborne droplets (showering, water-dependent heating/cooling systems)
no person-person transmission
entirely different than other pathogens involved in respiratory infections a newly emergent disease resulting from changing human behaviour
-
Example 4: Cryptosporidiosis and Giardiasis
common waterborne diseases in areas with regulated water supplies cysts or oocysts of these parasitic protozoa found in most surface waters
chlorine-resistant; dose rates can be low cryptosporidiosis in Milwaukee, WI affected over 400,000 people (spring 1993)
outbreak attributed to overburdened water supply system + spring rains and runoff from surrounding farmland into L. Michigan (source for supply system)
Giardia lamblia: flagellate; infects animals (e.g., beaver), humans
environmentally resistant cyst (~10 m dia) is infective agent ingested cysts germinate in intestine, resultant trophozoites grow on intestinal wall explosive, foul-smelling, watery diarrhea, cramps, flatulence, nausea, weight loss
Cryptosporidium parvum: infects variety of warm-blooded animals
resistant oocysts transmitted to new host via feces-contaminated water oocysts (~2-5 m) smaller than Giardia, more chlorine-resistant ingested oocysts germinate, trophozoites growth within epithelial cells of stomach,
intestine
mild, self-limiting diarrhea in healthy individuals chronic diarrhea in individuals with impaired immunity (+ possible
complications)
-
trophozoites
cyst stained
with iodine
Giardia lamblia life cycle (US CDC)
-
Giardia lamblia life cycle (US CDC)
-
E.COLI 0157:H7
Illness through food & water, undercooked, contaminated food
Enterohemorraghic, diarrhea, kidney failure
Highly virulence. 10-100 cfu can cause illness
Outbreak: 1982 in USA due to consumption of hamburger
-
SHIGELLOSIS
infectious disease caused by bacteria Shigella
Symptoms: diarrhea, fever, stomach cramps, bloody stool after 1-2days expose to bacteria. Last 5-7days.
-
WATERBORNE VIRAL
DISEASES
Waterborne viral diseases: many cause gastroenteritis (e.g., rotaviruses, Norwalk-like) may cause eye throat infections (e.g., adenoviruses) hepatitis (liver disease): hepatitis A, hepatitis E viruses polio: wild poliovirus been eliminated from western hemisphere
most are neutralized by chlorination
-
ENTEROTOXIGENICITY OF E.COLI INFECTION
-
ROTAVIRUS INFECTION
-
SHIGELLA INFECTION
-
AIR-BORNE INFECTIOUS
DISEASES
PART OF CHAPTER 8 OF THIS COURSE
-
WHATS THE PROBLEM TO HUMAN?
-
RESPIRATORY SYSTEM
-
Respiratory
System
-
OBJECTIVES
To describe transmission, prevention and control of respiratory
diseases caused by microbial agent (air pollutant) due to poor
environmental health.
Other types of air pollutants (PM, chemicals, Sox, Nox, Pb, VOC,
O3, DPM, smog, etc will discuss in separate chapter; Air pollution)
-
RESPIRATORY
DISEASES Air inside building contains 500-1000 microbes/cubic meter of air,
humans breathe 6 liters/min at rest. So up to 10,000 microbes per day enter lungs.
Air contains fungal spores, some bacteria.
But most infections occur by coming in contact with fluids from sneezes, coughs, hands of other infected people.
Respiratory infection l-develop colds just from inhaling droplets via sneezing or coughing. Hand contact is much more frequent, and rubbing eyes after contact is an especially effective way of getting virus into body.
Best defenses: Frequent hand washing and avoidance of close contact with infected people
-
SUMMARY OF EPIDEMIOLOGY FOR
TYPICAL RESPIRATORY DISEASE
-
EXAMPLES OF RESPIRATORY TRACT
PATHOGENS: COMMON COLD
The most common of all infectious diseases. Average American gets 2/year.
Over 200 different viruses may cause cold. Most are RNA viruses in rhinovirus or adenovirus family
Reproduce best at temperatures cooler than body temp. (33C rather than 37C), which is nasal pathway temp., so most infections occur in epithelial lining of nasal passageway.
Infection usually last a week or so, until antibodies to virus are made.
-
EXAMPLES OF RESPIRATORY
TRACT PATHOGENS: PNEUMONIA
One disease (inflammation in alveoli of lungs) -- many possible causes.
Normally occurs as secondary infection following viral infection or other ilness.
One of top 10 cause of death
Most frequent pathogen in many cases = Streptococcus pneumoniae.
Bacterium grows rapidly in alveoli, protected from phagocytosis by capsule. Lung spaces fill with blood, bacteria, phagocytes fluid buildup lung inflammation.
-
EXAMPLE OF RESPIRATORY TRACT
PATHOGENS: PNEUMOCYSTIS PNEUMONIA
a fungal disease, caused by Pneumocystis carinii, a yeast.
Used to be rare, but since AIDS, disease has exploded into prominence. In early days of AIDS, 80% of patients developed this
type of pneumonia.
In lung, Pneumocystis carinii elicits intense inflammatory response, produces foamy exudate of fluid. As infected cells die, leaves
honeycomb appearance.
Can be treated with certain antifungal antibiotics.
-
OTHER CAUSES OF
PNEUMONIA
Staph. aureus, often after influenza infection.
Legionella pneumoniae, first isolated in 1976 at a Legionnaire's convention. Bacteria can grow in water-cooling towers used for
air conditioners, was spread as fine aerosol in closed
buildings.
Mycoplasma pneumoniae, often spread by people living in close quarters (schools, military barracks)
-
Diphtheria
Caused by bacterium Corynebacterium diphtheriae.
Infection can lead to a "pseudomembrane" covering the posterior pharynx (back of the throat to you non-clinical types).
Diphtheria toxin: Toxins released by the organism create an inflammation on the pharyngeal mucosal surfaces. The pseudomembrane may obstruct breathing to the point of asphyxation and death. The toxin may travel to the heart and lead to heart failure
-
STREPTOCOCCAL
DISEASES
Streptococcus pyogenes-microbiota of 5-15% of humans,
usually in respiratory tract, usually not producing obvious
disease.
Streptococcal infections can produce a family of diseases -
examples:
suppurative (pus-forming) infections
pharyngitis (sore throat)
scarlet fever (extensive skin rash)
impetigo (infection of superficial skin layers
cellulitis (infection of deep skin layers)
necrotizing fasciitis (bacteria attack and destroy muscle tissue)
streptococcal toxic shock syndrome
-
TUBERCULOSIS
M. tuberculosis is a strictly aerobic bacterium, with a very slow doubling time (12-18 hours)
long latent period; antibody response are 8-12 weeks after infection.
TB is usually asymptomatic; only 10-20% of infected persons become diseased.
How does M. tuberculosis cause disease? any, but lung is common focus of infection, so consider sequence of infectious TB in lung:
Bacterium is taken up inside phagosome by macrophage (first stage of phagocytosis), grows and replicates & form tubercule which may spread through respiratory system and other tissues
Patients with pulmonary TB have respiratory problems, cough up mucus secretions frequently. TB can attack many other sites in body as well as lungs.
TB is one of the most common diseases world-wide.
Worldwide annual deaths from TB: 3 million (98% in developing countries)
Worldwide annual reported disease cases: 8 million Worldwide incidence of infection: somewhere between 1 in 10 to 1 in 3
people
-
LEPROSY
Mycobacterium leprae
Bacterium cannot be grown in culture, only in footpads of
armadillos (lower body temperatures).
One of the most dreaded (and joked about) of diseases.
Still a major problem, 14 million people worldwide,
Transmission is still a mystery. Most people who come in
contact with lepers do not get infected. Lepers have high
bacterial counts in nasal discharges, but disease does
not spread in epidemic fashion.
Disease manifestation: 2 types
Lepromatous leprosy. The worst form of the disease,
bacteria spread to every organ and part of body. Can
lead to loss of fingers, toes, nasal deformation,
eventually death.
Tuberculoid leprosy. Mild disease, symptoms due to
delayed hypersensitivity to proteins. Full recovery often
occurs.
-
INFLUENZA
infectious disease of birds and mammals
fever, sore throat, muscle pains, severe headache, coughing, and weakness and fatigue
Pneumonia
Can be confused with common cold. Flu is much more severe!!!
-
INFLUENZA VIRUS
RNA, enveloped
Viral familyorthomyxoviridae
Size80-200nm in diameter
Three types
A, B, C
Surface antigens
H (haemaglutinin)
N (neuraminidase)
Highly contagious
Incubation 2days (1-4days)
Mode of transmission
Droplet (conjunctiva, nasal and nasal mucosa)
Airborne Contact
Viral Survival
Humidity (35-40%), 28oC 1-2days on nonporous
surface
Can undergo antigenic shift and drift
-
NATURAL HOST OF INFLUENZA VIRUS
-
PANDEMIC FLU
Bird Flu
Human Flu
Swine Flu
Horse Flu
Dog Flu
-
ANTIGENIC SHIFT: RE-ASSORTMENT
In human
-
ANTIGENIC SHIFT: RE-ASSORTMENT in pigs
-
ANTIGENIC DRIFT: MUTATION
In human
-
EXAMPLE 1: SARS- BIRDS TO HUMAN
Hong Kong, SAR
China, 1999, H9N2
The Netherlands,
2003, H7N7
Hong Kong, SAR
China, 2003, H5N1
Hong Kong, SAR China, 1997, H5N1-Hundreds of infections
with H5N1 bird flu (over a short timeframe)
18 hospitalizations
6 deaths
-
BIRD FLU -WORLD-WIDE THREATS
Wash. Post, Dec. 16, 1997
-
EXAMPLE 2: H1N1 INFLUENZA
Spanish flu-1918
Global death total: 50 million to 100 million
In 6 months 20 million deaths
The greatest medical holocaust in history" and may have killed as many people as the Black Death
was misdiagnosed as dengue, cholera, or typhoid
category 5 influenza CDC pandemic severity index (ie: projected death in USA 2 Million)
-
H1N1 PANDEMIC- 2009
Refer to swine flu
Over 182166 reported cases, 1799 death, in 177
countries
rates of influenza illness continue to decline in the
temperate regions
Tropical Asia -increasing rates of illness as they
enter their monsoon season
India, Thailand, Malaysia, and Hong Kong-have
active surveillance programs
-
H1N1PANDEMIC- 2009
-
MALAYSIA
Nipah virus outbreak in 1999,
Severe Acute Respiratory Syndrome (SARS) not affected
(H5N1 (bird flu) outbreak in 2004.- not affected
National Influenza Pandemic Preparedness Plan
(NIPPP) which serves as a time bound guide for
preparedness and response plan for influenza
pandemic.
HINI in 2009
-
STRATEGY TO SLOWDOWN
H1N1 ANTIVIRAL DRUG &
VACCINE Oseltamivir (trade name Tamiflu)
Zanamivir (trade name Relenza)
-
PUBLIC RESPONSE
Social distance
Respiratory hygiene
Mask (N95 mask for health-care worker)
Hygiene
Risk communication
-
PANDEMIC PROBLEMS
Not enough vaccine
Not enough antivirals (oseltamvir)
Classical epidemic control
Physical restriction of people
Isolation of the sick
Quarantine of the exposed
Ban all public gatherings: work, school, shopping malls, theaters, churches, and yes, bars and clubs
-
BENEFIT OF PANDEMIC
INFLUENZA PLANNING AND
FEARS
Silver lining factor
Improved surveillance
Planning for vaccine strategies, vaccine supply
Attention of media, governments, markets
May break the vicious cycle of neglect, followed by no effort or investment
-
END OF CHAPTER