MT6312 LEC UNIT 3 Flashcards
Communicable diseases: infectious or noninfectious?
Infectious
Infectious agents include?
Bacteria
Fungi
Virus
Parasites
condition that results when a microbe can invade the body, multiply, and cause injury or disease.
Infection
Some pathogenic microbes cause infections that are communicable
“Communicable Pathogens”
microbe that can cause disease
“True Pathogen”
organisms that can become pathogenic once host immunity is low/is present in body location that is unusual for the microbe to be present
“Opportunistic Pathogen”
Microbe that is normally present in body locations; not usually causing infection
Microbiota/Normal Flora
In-charge with the investigation and control of various diseases, especially those that are communicable and have epidemic potential
Centers for Disease Control and Prevention
Centers for Disease Control and Prevention is an agency of?
U.S. Department of Health and Human Services
Robert Koch’s Postulates are?
The microorganism or other pathogen must bepresent in all cases of the disease
The pathogen can be isolated from the diseased host andgrown in pure culture
The pathogen from the pure culture mustcause the disease when inoculated into a healthy, susceptible laboratory animal
The pathogen must bereisolatedfrom the new host andshown to be the sameas the originally inoculated pathogen
Epidemiologic triad consists of?
Host
Agent
Environment
Vector (MIDDLE)
Six key components of links in the chain of infection?
infectious agent, a reservoir, an exit pathway, a means of transmission, an entry pathway, and a susceptible host.
place where the pathogen lives and multiplies.
Reservoir
method an infectious agent uses to travel from a reservoir to a susceptible individual.
MOT
Examples of MOTs?
Airborne, contact, droplet, vector, and vehicle
Body part where pathogen can lodge/enter the host
Entry pathway
Person with low/altered immunity that receives the pathogen
. Susceptible Host
way an infectious agent is able to leave a reservoir host.
Exit pathway
exposure of infected body fluids such as blood or saliva
Direct contact
pathogens remain on surfaces that were in contact with an infected person
Indirect contact
infectious agents are found in contaminated food and water that are ingested
Food and water borne
pathogens are spread when an infected person coughs or sneezes
Airborne
infectious agents are usually transmitted through a bite of an infected insect carrying the infective agents of the organisms
Vector-borne
Malaria means?
bad air
Malaria is caused by?
apicomplexan parasites of the genus Plasmodium
Medically important species of Plasmodium infecting humans
Plasmodium falciparum – 60.8%
Plasmodium vivax – 14.1%
Plasmodium ovale – 3.7%
Plasmodium malariae – 2.5 %
Life threatening plasmodium?
P. falciparum
P. vivax
P. knowlesi
All erythrocytes infected?
P. falciparum
P. knowlesi
Senescent erythrocytes infected?
P. malariae
Endemicity is Global, most common in Africa
P. falciparum
Endemicity is mostly in Asia
Vivax
Endemicity is in africa only
Ovale
Endemicity is globally
Malariae
Endemicity is in Malaysia and neighboring countries
Knowlesi
Rare CNS involvement
Vivax
Malariae
Incubation of 18-40 days
Malariae
Incubation of 8-11 days
falciparum
Incubation of 8-17 days
Vivax
Incubation of 10-17days
Ovale
9-12 days incubation
Knowlesi
Plasmodium stages in man
Schizont 🡪 Trophozoite 🡪 Gametocyte
dividing forms of plasmodium
Schizont
Growing forms of Plasmodium
Trophozoite
Sexual forms of Plasmodium
Gametocyte
Stages of Plasmodium in the mosquito
Zygote 🡪 Ookinete 🡪 Oocyst 🡪 Sporozoite
Union of gametocytes leads to?
Zygote
Spindle shapes seen in the gut of the mosquito
Sporozoite
Malaria can be prevented by the use of?
antimalarial drugs and use of protection measures against mosquito bites.
To avoid mosquito bites, the CDC recommends?
Insect repellent (20-35% DEET)
Long sleeved clothing
Mosquito nets (w/ permethrin)
Insecticide on clothing
Pyrethrin before going to bed
What model is used for Malaria prevention?
Swiss cheese model
What is the Swiss cheese model?
Awareness of risk and prevention
Bite prevention
Chemoprophylaxis
Diagnosis and access to treatment
Emergency treatment kits
Primary prevention for malaria includes?
Vector control
Secondary prevention for malaria includes?
Bite prevention
Chemoprophylaxis
Tertiary malaria prevention includes?
Diagnosis and Emergency standby
acute diarrheal disease that can kill within hours if left untreated.
Cholera
Up to 80% of cases of Cholera can be successfully treated with?
oral rehydration solution (ORS).
Severe cases of cholera will need?
rapid treatment with intravenous fluids and antibiotics
What are critical to control the transmission of cholera and other waterborne diseases?
Provision of safe water and sanitation
Should be used in conjunction with improvements in water and sanitation to control cholera outbreaks and for prevention in areas known to be high risk for cholera
Safe oral cholera vaccines
Where does bacteria multiply for cholera?
Large intestine
World’s longest running pandemic
Cholera
Cholera agent
Vibrio cholerae
Incubation period of cholera
2hrs - 5 days
Feces from cholera infected can be infective for as long as?
14days
Cholera control multi-sectoral interventions?
Water, sanitation, hygiene
Surveillance and reporting
Use of oral vaccines
Community engagement
Healthcare system strengthening
Leadership and coordination
Other name for ebola virus
EBOLA HEMORRHAGIC FEVER
Bundibugyo virus, Sudan Virus, Tai Forest virus, Zaire Ebola virus
Morphology of ebola virus
Shepherd’s crook morphology, ”U” or “6” shape
Form of ebola that cause disease in primates
Reston virus
highly virulent and require maximum containment facilities for laboratory work
Filovirus
Highly virulent strains of ebola
Zaire and Sudan
Most dangerous of the known EVD-causing viruses.
Zaire
Marburg virus and Ebola virus
Filovirus
Biosafety level of filovirus
4
The natural/reservoir hosts for ebola
Bats (fruit bats)
Infections in _________ imported into the United States from the Philippines but none of the workers became sick, resulted in Ebola Reston
cynomolgus monkeys (long-tailed macaque)
A high mortality rate among ____ in the Philippines in 2008 led to the discovery of Ebola Reston virus in animals other than primates.
pigs
Ebola Reston: (low/high) pathogenicity to humans
low
T or F: Ebola Reston Virus strain can infect humans without causing disease
T
For Ebola, animals may become infected when they?
eat fruit partially eaten by bats carrying the virus
Human consumption of ______ has been linked to animal-to-human transmission of Ebola
bushmeat
What is bushmeat?
Fruitbats hunted down as food
Clinical manifestations of ebola?
Fever, headache, sore throat, muscle pain
Abdominal pain, vomiting, diarrhea, rash
Severe dehydration
Internal and external bleeding
Impaired humoral immune responses
Filovirus infection appear to be?
immunosuppressive
Ebola fever is usually higher than what temperature?
38.3°C
Death due to ebola, if it occurs, is often due tolow blood pressure from fluid loss, causing?
Hypovolemic shock
T or F: Bleeding into the whites of the eyesmay also occur in Cholera
F, Ebola
Ebola spreads by direct contact with?
blood or other body fluids: Body fluids: saliva, mucus, vomit, feces, breast milk, urine, and semen
According to WHO, only people who are very sick are able to spread Ebola disease in _______ and through ________
saliva and through large droplets
What other ways can ebola be spread?
Contaminated needle and syringes
People at risk for ebola?
Direct contact with an infected person
Healthcare workers treating people with Ebola
Poor health system; not capable of isolation procedures
Practicing traditional burials and embalming
Ebola virus is known to persist in where?
immune-privileged sites in some people who have recovered from Ebola virus disease
the testicles, the inside of the eye, and the central nervous system
In women who have been infectedwhilepregnant, the virus persists in the _______,______,________
In women who have been infectedwhile breastfeeding, the virus may persist in ________.
placenta, amniotic fluid and fetus.
breast milk
T or F: Dead bodies remain infectious for Ebola
T
Ebola has the highest mortality rate of all the viral hemorrhagic fevers, about how many percent?
25-90%
Average case fatality rate for ebola?
50%
The largest outbreak to date was the Ebola virus epidemic in?
Large number of deaths in?
West Africa
Guinea, Sierra Leone, and Liberia
Largest Ebola outbreak ever documented – involved major urban areas
2013 – 2016 West African Outbreak
2013 – 2016 West African Outbreak major outbreak in what country? and spread to?
Guinea spread to Libera, Sierra Leone
First known outbreak of EVD
1976 Sudan Outbreak
Second outbreak (Democratic Republic of the Congo)
1976 Zaire ebolavirus
In the 1975 Ebola Outbreak in Africa, the first person infected with the disease was?
the village’s headmaster who was originally believed to have malaria
DIAGNOSIS of Ebola?
Enzyme-Linked Immunosorbent Assay (ELISA)
Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) assay
Electron Microscopy
Virus Isolation by Cell Culture
For routine diagnostic management of Ebola
Automated or semi-automated nucleic acid tests (NAT)/ PCR
Specimen for Ebola and Findings
SPECIMEN: whole blood; oral fluid specimen
Laboratory Findings: low white cell count, platelet count, and elevated liver enzymes
TREATMENT for Ebola
No specific antiviral therapy
Maintaining renal function and electrolyte balance
Supportive care-rehydration with oral or IV fluids
Combating hemorrhage and shock
Experimental Ebola vaccine: rVSV-ZEBOV
Prevention and control international guidelines for Ebola
Hygiene (avoid contact with body fluids)
DO not come in contact with infected person’s body fluids
Avoid burials with handling a dead infected person
Returning travelers and healthcare workers should be surveilled for 21days
Isolate suspected patients
Contact tracing
Infectious diseases, also known as?
infectiology
medical specialty dealing with the diagnosis and treatment of complex infections.
Infectious diseases or infectiology
An infectious disease specialist’s practice consists of managing what kind of infections?
nosocomial (healthcare-acquired) infections or community-acquired infections
Disease specialists are historically associated with?
travel medicine and tropical medicine.
interdisciplinary branch of medicine that deals with health issues that occur uniquely, are more widespread, or are more difficult to control in tropical and subtropical regions.
Tropical medicine
Tropical medicine mostly deals with infections that are (epidemic/endemic)
Endemic
Well-known tropical diseases?
malaria, HIV/AIDS, and tuberculosis.
Tropical medicine specialists must be knowledgeable in?
18 lesser known neglected tropical diseases, which include Chagas disease, rabies, and dengue.
Directed the WHO Smallpox Eradication program
Dr. D.A. Henderson
infectious microorganism or pathogen: a virus, bacterium, parasite, or other microbe.
Agent
T or F: Presence of agent only can be enough to cause disease
F, presence of that agent alone is not always sufficient to cause disease.
human who can get the disease
Host
A variety of factors intrinsic to the host, sometimes called _____, can influence an individual’s _____,______ or______.
risk factors
exposure, susceptibility, or response to a causative agent.
Opportunities for exposure are often influenced by ______ and ________
behaviors and physiologic susceptibility
extrinsic factors that affect the agent and the
opportunity for exposure.
Environment
Environmental factors include?
physical factors, biologic factors, and socioeconomic factors
useful framework in the design of prevention and control measures as specific strategies can be aimed at various points along the chain of infection
Chain of Infection
Strategies or actions aimed at eradicating, eliminating or minimizing the impact of disease and disability, or if none of these are feasible , retarding the progress of disease and disability.
Prevention
Control of the disease involves ongoing operations at reducing the?
- Incidence of Disease
- Duration of disease
- Effects of the disease
- Burden to community
Prevention is (individual/community level)
Individual
have no nonhuman reservoir
pathogenic viruses, including smallpox, measles and polio
Only three countries continue to have endemic polio—____,______,______—but eradication from these countries has proven extremely difficult.
Nigeria, Pakistan, and Afghanistan
offers an example of what happens when public health relaxes its vigilance
Measles
Public Health Issues on Vaccines and AMR
- Dipping Vaccine confidence
- MDR and XDR TB
- Nosocomial infections and “superbugs”
- Improper use and disposal of antibiotics
- Antibiotics in industrialized agriculture
Vaccine confidence is believed to be related to?
Vaccine hesitancy and acceptance
Delay or refusal of vaccines despite availability of services
Vaccine hesitancy
Adherence to the recommended schedule and measured by past behavior, willingness to comply in the future
Vaccine acceptance
Happens when bacteria change and become resistant
Antibiotic resistance
The more we take antibiotics, the (more/less) chance bacteria becomes resistant
More
Factors contributing to emergence
Agent
Host
Environment
How does the agent contribute to disease emergence?
Evolution
Resistance to drugs
Resistance of vectors to pesticides
How does the host contribute to disease emergence?
Demographic change
Behavior
Susceptibility
Poverty/Social Inequality
How does the environment contribute to disease emergence?
Climate change
Economic development and land use
Technology and industry
International travel and commerce
Public health measure
Deterioration of surveillance systems
Emerging infectious diseases are diseases that?
Have not occurred before
Occurred previously but only little were affected
Occurred throughout history but only recently recognized
Examples of emerging infectious disease
Lassa fever
Ebola
Legionnaire disease
Hemolytic uremic syndrome
Lyme diease
AIDS
Gastric ulcers
CHolera
Hantavirus pulmonary syndrome
Influenza
Once were major health problems but declines dramatically, but are again becoming health problems for significant proportion of the population
Re-emerging infectious disease
Examples of re-emerging?
Cryptosporidiosis
Diphtheria
Malaria
Meningitis, necrotizing fascitis
Pertussis
Rabis
Rubeola
Schistosomiasis
TB
Yellow fever
infection that can be passed through vaginal, oral or anal sex.
STI
Most STIs are transmitted through the exchange of sexual fluids, but some can be passed through?
skin to skin genital contact or through contact with blood and other bodily fluids.
STDs are now called?
“sexually transmitted and blood- borne infections (STBBIs)”.
T or F: STBBIs always has visible symptoms
F, may or may not
Common STBBIs
Chlamydia
Herpes
Gonorrhea
Hepa ABC
Chlamydia is an infection caused by the bacterium?
Chlamydia trachomatis
Genital herpes is an infection caused by?
Herpes simplex
People with genital herpes remain infected for how long?
For the rest of their lives
T or F: Chlamydia infections always show symptoms
People with chlamydia most often do not show symptoms.
Gonorrhea is an infection caused by the bacterium?
Neisseria gonorrhoeae
T or F: A person can have gonorrhea more than once in his or her life.
T
attacks and weakens the immune system.
infected person is then affected by various other diseases and infections.
HIV
In time, if the HIV infection is not treated, it can develop into?
AIDS
T or F: People with HIV/AIDS can get well
NO
What is HPV?
- Human Papillomavirus (HPV)
Other infection caused by the bacterium Chlamydia trachomatis
- Lymphogranuloma Venereum (LGV)
Syphilis is an infection caused by the bacterium?
Treponema pallidum.
T or F: People who were infected with syphilis may be infected without knowing
T
Preventive medical treatment started immediately after exposure to pathogen(HIV) in order to prevent infection by the pathogen and the development of the disease;
Post-exposure Prophylaxis
Process of providing an individual with information on the biomedical aspects of HIV AIDS, and emotional support to any psychological implications of under going HIV testing and the test result itself before the individual is subjected to the test;
Pre-test Counseling
process of providing risk- reduction information and emotional support to a person who submitted to HIV testing at the time the result is released;
Post-test Counseling
“index client”, “source”, or “patient” who has a sexually transmitted infection (STI) including HIV, is given support in order to notify and advise the partners that have been exposed to infection.
Partner Notification
voluntary agreement of a person to undergo or be subjected to a procedure based on full information, whether such permission is written or conveyed verbally;
Informed Consent
groups or persons at higher risk of HIV exposure, or affected populations whose behavior make them likely to be exposed to HIV or to transmit the virus;
Key Affected Populations
legal principle that recognizes the capacity of some minors to consent independently to medical procedures, if they have been assessed by qualified health professionals to understand the nature of procedures and their consequences to make a decision on their own;
Mature Minor Doctrine
core duty of medical practice where the information provided by the patient to health practitioner and his/her health status is kept private and is not divulged to third parties.
Medical Confidentiality
T or F: There is HPV vaccine for men
F, only for women
Can also happen when new strains of known disease- causing organisms appear.
Re-emergence
The majority of STIs (have/do not have) symptoms
Do not have
HIV is a ____; it hides in the ___
retrovirus; cells
HIV must enter the ___ for infection
Bloodstream
T or F: Kissing spreads HIV
F
______ viruses circulate and cause seasonal epidemics of disease.
Influenza A and B
What subtype of influenza: detected less frequently and usually causes mild infections
C
What subtype of influenza: primarily affect cattle and are not known to infect or cause illness in people.
D
Break the Chain: steps of infection prevention
- Stop the source
- Block exit portal
- Interrupt MOT
- Protect entry portal
- Increase host defensiveness
How do vaccines work?
Weak or dead bacteria introduced via injection in the patient
WBCs activated to produce antibodies
T or F: Not everyone infected with TB bacteria becomes sick.
T
One cough can release _____ droplet nuclei. (TB)
3,000
As few as ___ M. tuberculosis MTB bacilli are necessary for human infection
five
Is TB curable?
Yes
The treatment for TB is?
a combination of 3-4 anti-TB drugs.
What instance can worsen TB condition?
prescribing a SINGLE DRUG for TB treatment
What kind of TB: resistant to isoniazid and rifampacin
MDR-TB
Influenza A viruses are classified into subtypes based on combinations of?
Hemagglutinin (HA) and Neuraminidase (NA)
Influenza circulating in humans?
A(H1N1) & A(H3N2)
continuously monitors the influenza viruses circulating in humans and updates the composition of influenza vaccines
WHO Global Influenza Surveillance and Response System (GISRS)
WHO Global Influenza Surveillance and Response System (GISRS) monitors influenza virus how often?
2x/year
Large family of viruses with widely-spaced projections or spikes on the outer surface of the envelope, suggestive of a solar corona.
COVID
Coronavirus disease (COVID-19) caused by?
Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)
COVID is transmitted between?
animals-humans = zoonotic
SARS virus originated in a nonhuman host, most likely ___, was amplified in ____, and was transmitted to humans in live animal markets
bats
palm civets
MERS-CoV likely originated in ___ and became widespread in ____.
bats
camels
In the case of the 2019 coronavirus, there is some evidence it went from a ___ to a _____ before infecting a human in Huanan Market, Wuhan, China
bat
pangolin
In the case of COVID, the results of aerosols of particles are more likely from medical procedures such as_____,_____ and ______
manual ventilation, suction, and bronchoscopy.
Dengue vector?
Mosquitoes of the Aedes group, especially Aedes aegypti and Aedes albopictus are responsible for transmission
Aedes mosquitos also spread?
Zika, Chikungunya, and other viruses
Dengue is endemic where?
endemic throughout the tropics and subtropics
Dengue incidence increased ___ over the last 50 years
30-fold
Dengue fever is most common in?
Southeast Asia
”Asian” genotypes of ____ and _____ are associated with severe disease accompanying _______
DENV-2 and DENV-3
secondary dengue infections
PH is ranked ___ in dengue burden in southeast Asia
4th
Peak season of dengue in PH
rainy season (May – November)
Case fatality of Dengue in PH
Case fatality rate 0.55%
Economic burden of Dengue in PH?
- loss of productivity
- premature death
- increased healthcare cost
- reduction in tourism
____ is one important driver of the current distribution and incidence of dengue.
Climate
_____ was the most important predictor of distribution of dengue
temperature
_____ of the primary Aedes mosquito vectors are expanding. This may lead to a greater burden of dengue in low- and middle-income countries.
The geographic ranges
When should dengue be suspected?
when a high fever (40°C/104°F) is accompanied by 2 of the following symptoms: severe headache, pain behind the eyes (retro-orbital pain), muscle and joint pains, nausea, vomiting, swollen glands or rash
Diagnosis of Dengue
Positive tourniquet test
low white cell count
Virus cell culture
PCR: Nucleic Acid Detection [ RT-PCR ]
Viral antigen detection : NS1 (nonstructural protein 1)
Antibody testing (Serological test): ELISA
T or F: There is treatment for dengue
F
Case management of dengue?
- Maintaining proper fluid balance
- Daily follow up and oral rehydration therapy
- Intravenous hydration
- Blood transfusion
T or F: No prophylaxis is available to prevent dengue
T
At present, the main method to prevent the transmission of dengue virus is to?
combat vector mosquitoes
The World Health Organization recommends what program?
Integrated Vector Control program
Vector control includes?
Biologic control
Chemical control
Environmental management
BIOLOGIC CONTROL consists of?
Breeding of fish
Predatory copepods
Used to eliminate mosquitoes from larger containers used to store potable water
Fish
most commonly used for biologic control in dengue; adapt well to confined water bodies
Guppies
Chemical control consists of?
Indoor Residual Spraying
Space Sprays
application of long-acting chemical insecticides on the walls and roofs of all in a given area
Indoor Residual Spraying
Massive , rapid destruction of the adult vector population
Recommended for control only in emergency situations to suppress an ongoing epidemic
Method of release: aircraft, vehicle,, hand held equipment
Space Sprays
Environmental control includes?
Environmental modification, manipulation
Changes to human habitation or behavior
Environmental manipulation consists of?
- Mosquito-proofing of water-storage containers
- Solid waste management
- Street cleaning
- Building structures
Improvement of water supply and water- storage systems
Environmental modification
Dengue immunization vaccine is?
Dengvaxia
Dengvaxia: The live attenuated dengue vaccine ____ has been shown in clinical trials to be efficacious and safe in persons who have had a previous dengue virus infection
CYD-TDV
carries an increased risk of severe dengue in those who experience their first natural dengue infection after vaccination
Dengvaxia
For countries considering vaccination as part of their dengue control program, what is a recommended strategy?
Pre-vaccination screening
Decisions about implementing a pre- vaccination screening strategy will require ______ at the ______ level, including consideration of the sensitivity and specificity of available tests and of local priorities, dengue epidemiology, country- specific dengue hospitalization rates, and affordability of both CYD-TDV and screening tests.
careful assessment; country
should be considered as part of an integrated dengue prevention and control strategy
Vaccine
Infect the mosquito population with bacteria of the genus?
WOLBACHIA
What is WOLBACHIA?
self-perpetuating intracellular bacteria with disease blocking action, makes mosquito resistant to dengue virus
Rate of spread of Wolbachia in Aedes populations appears very (slow/fast)
Slow
