Part III: Infectious Disease Epidemiology
Epidemiological Triad for Infectious Disease
Notifiable DiseasesAcute Flaccid Paralysis AIDS Amoebiasis Anthrax BotulismBrucellosis Campylobacteriosis Chancroid Chickenpox Chlamydia, Genital Cholera Creutzfeldt-Jakob Disease Cryptosporidiosis Cyclosporiasis Diphtheria Giardiasis Gonorrhea Gonococcal Ophthalmia Neonatorum Group B Streptococcal Disease of the Newborn Hantavirus Pulmonary Syndrome Hepatitis A Hepatitis B Hepatitis C Hepatitis Non-A, Non-B Human Immonodeficiency Virus Influenza,Laboratory-Confirmed Invasive Haemophilus influenzae type b Disease Invasive Group A Streptococcal Disease Invasive Meningococcal Disease Invasive Pneumococcal Disease Legionellosis Leprosy Listeriosis (all types) Malaria Measles Meningitis, Pneumococcal Meningitis, Other Bacterial Meningitis, Viral Mumps Paratyphoid Pertussis Plague* Poliomyelitis Rabies Rubella Rubella, Congenital Salmonellosis Shigellosis Smallpox Syphilis, All Syphilis, Congenital Syphilis, Early Latent Syphilis, Early Symptomatic (Primary and Secondary) Syphilis, Other Tetanus Tuberculosis Tularemia Trichinosis Typhoid Verotoxigenic E. coli1990 -Viral Hemorrhagic Fevers (Crimean Congo, Ebola, Lassa, Margurg) West Nile Virus Asymptomatic Infection West Nile Virus Fever West Nile Virus Neurological Syndromes West Nile Virus Unclassified/ Unspecified Yellow Fever
Emerging communicable disease
Cryptosporidium parvum 1976 Ebola virus 1976 Legionella 1977 Campylobacter jejuni 1977 E. Coli 0157:H7 1982 HIV 1983 Hepatitis C 1989 nv CJD 1996 Avian influenza ( Type A H5N1) 1997 WNV 1999 SARS 2003 ……… Pandemic influenza???
Basics of Disease Transmission
Chain of Infection
Contact (Host)
Reservoir
Agent
Environment
Iceberg of infectious disease
Course of Disease
Incubation period Illness
Infected Infectious
Latent Period
ImmunityActive
infection immunization
Passive immunoglobulin intrauterine
Herd Immunity
Portals of Entry for InfectionRespiratory tractGenitourinary tractGastrointestinal tractSkin / Mucous membraneTransplacentalParenteral( percutaneaous , via blood)
Modes of Transmission
Direct Direct contact (bite,soil,touch) Droplet spread Vertical transmission (through
placenta)
Indirect Airborne (droplet nuclei , dust
particles) Vehicle borne (food, water) Vector borne ( mosquito) Mechanical ( flies)
Opportunities for interrupting transmission
Immunization
Infection control
Treatment
Isolation
Chemoprophylaxis
Improve general environment
Vehicle control Quarantine
Herd immunity
Physical protection
Opportunities for interrupting transmission
Reservoir Infection control measures,treatment,isolation
Susceptible contact chemoprophylaxis, immunization (active and
/or passive),quarantine , physical protection Route of transmission
food preparation , water purification, vector control
Agent Infection control measures, treatment
Investigation of disease outbreaks
Epidemics Epidemics are temporary increases in the
incidence of disease in populations• E.g. Infectious Disease- SARS, West Nile Virus• E.g. Non-infectious Disease- Asthma deaths in the
1960s associated with increased use of pressurized aerosol broncholdilators
Increases in incidence are usually significantly above the level expected from past experience in the same population
Epidemics and OutbreaksThe occurrence of cases of an illness clearly in
excess of expectancy
Examples of recent epidemics: HIV / AIDS- Retrovirus; Ebola- African filovirus via monkey; causes viral
hemorrhagic fevers (VHF); often fatal; Hanta virus (US)- Bunyavirus via rodents; causes
severe infections of the lungs and kidneys; Lyme disease (US)- Borrellia burgdorferi bacteria
via tick bite; symptoms include: fatigue, fever, stiff muscles/joints, meningitis, arrhythmias, arthritis.
Definitions Primary or index case- the first case (or group of
cases) arising from the introduction of an agent in to a community
Secondary case- people who acquire infection from the primary case(s)
Incubation period- the time interval between infection of an individual and the onset of symptoms
Generation time- the time interval between the onset of primary and secondary cases
Derived infection- this is an infection arising by direction transmission from an infected contact
Types of Epidemic There are two main types of epidemic: common
source and propagated Point or Common Source Epidemics- result from
the exposure of a group of people to the same source of infection or noxious substance. Continuous exposure or intermittent exposure of the population to the causal agent produces a more extended and irregular epidemic curve. • E.g. outbreak of Salmonella typhimurium food
poisoning amongst delegates ate a medical conference• E.g. outbreak of respiratory disease due to adulterated
cooking oil in Spain
Propagated (Person-Person) Epidemics
• Propagated epidemics are due to the transmission of infectious agent from one person to another. The epidemic curve usually shows a gradual rise and decline, often with further waves as each successive generation of cases infects a new generation.
•E.g. An outbreak of measles occurred in a primary school. After two index cases , there were two epidemic waves at approximately 10-14 days intervals. The outbreak was modified by those vaccinated. The attack rate among those unvaccinated was 86%.
Investigation of an OutbreakStages In Investigation
• Descriptive enquiries into the facts of the outbreak
• Investigative reservoirs and vehicles of infection
• Analysis of the data collected• Formulation of a causal hypothesis• Testing its validity in the control of the
outbreak
Descriptive enquiries Verify the diagnosis by clinical and laboratory
investigations Verify the existence of the epidemic by
comparison with previous incidence of the disease in the same population
Compile a list of all cases Investigate patients and others who might be
involved in the case (i.e. age, sex, occupation, address etc.)
Ensure all clinical and laboratory investigations required to confirm the identity of the infection in patients were carried out
Investigate reservoirs and vehicle of infection
Human- an epidemic may originate from an individual who a minor clinical episode or is a carrier of disease
Animal- enquire about the contacts patients may have had with sick animals or animal products
Environment- investigate sources of foods consumed by individuals and the circumstances of their production, storage, preservation and preparation. Arrange for laboratory examination of food, water supplies and other environmental sources and typing of any organisms that are isolated
Analysis of the data collected
Plot of the epidemic curve- this may give some clue to the mode of spread and probable time of initial exposure
Plot the cases on a map- this will detect clustering and the distribution of cases
Analyze the incidence rates in different groups- for example by age, sex or occupation. Attack rates must be calculated among both exposed and non-exposed
Look for a quantitative relationship- this may exist between the degree of exposure (or dose) and attack rate
Formulation of a causal hypothesis
Factors for hypothesis:• The properties of the agent, it’s reservoirs, favored
vehicles and the nature of illness• The probable source and route of transmission• Time and duration of exposure of the patients to
the agent in relation to the onset of their illness• Attack rates of the different sub-groups of the
population at risk
Testing validity in the control of the outbreak
Seek support for the causal hypothesis by further investigation of cases, if necessary, to confirm the proposed explanation of their illness
Implement appropriate control measures on the assumption that the hypothesis is correct and monitor their success in reducing the incidence of further cases
Epidemic Curves # cases by time of onset Shape of the curve gives you clues: Agent known: use incubation period to look
back at exposure Agent unknown (but common event likely):
postulate agent by determining the incubation period
Draw the curve relative to specific sites/groups
Epidemic Curves: Point Source
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Salmonellosis in passengers on a flight from London to the US by time of onset, March 13-14, 1984
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Epidemic Curve: Propagated or Person-Person
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VHF Deaths, Bandudo Province, ZaireMarch - April 1995
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Occurrence/Cessation of an Outbreak
There are numerous conditions that might change and precipitate an outbreak, although all lead to an increase in the number of exposed and susceptible persons required for an outbreak. Some include:• The new appearance of or sudden increase in an
infectious agent or toxic material• The arrival of susceptible to an environment
which has an endemic pathogen• The introduction of an effective route of
transmission from source to susceptible (e.g. climatic change and malaria)
Question 1.The quarantine or surveillance periodprescribed for a specific infectious disease is based upon:
(a) Incubation period of the disease(b) Epidemic cycle of the disease
(c) Period of infectivity of the disease(d) Normal maximum duration of acute
symptoms(e) Proportion of susceptibles in the
contact population
Question 1.
Answer
(a) Incubation period of the disease
Question 2.The isolation period prescribed for a specific infectious disease is based upon:
(a) Incubation period of the disease(b) Epidemic cycle of the disease(c) Period of infectivity of the disease(d) Normal maximum duration of acute
symptoms(e) Proportion of susceptibles in contact
population
Question 2.
Answer
(c) Period of infectivity of the disease
Question 3.When is the isolation of infectious disease cases most useful as a method of preventing new cases?
a) During the period before the onset of clinical diseaseb) When the ratio of unapparent to apparent cases is
highc) During period of greatest communicability occurs
after onset of the diseased) Isolating cases of infectious disease is never a
useful method of preventing new casese) Isolating cases of infectious disease is always a
useful method of preventing new cases
Question 3.
Answer
(C) During period of greatest communicability occurs after onset
of the disease
Question 4.An outbreak of measles occurred in an elementary school with an enrolment of 300 pupils. During October and November, 72 pupils in the school were absent with measles.
(a) Compute the attack rate for October and November
The 72 pupils with measles had a total of 100 brothers and sisters living at home. Of the siblings, 20 subsequently developed measles during October through December.
(b) Compute the secondary attack rate among the siblings.
Question 4.
Answer
(A) 24%
(B) 20%
Question 5.
With one exception, all the following diseases are notifiable in Saskatchewan. The one exception is:(a) HIV infection(b) Gonorrhea(c) Non‑gonococcal urethritis(d) Chancroid(e) Chlamydia
Question 5.
Answer
(c) Non‑gonococcal urethritis
Question 6.In Canada, which of the following methods of transmission apply
BEST to each of the four diseases mentioned below?
(a) Person‑to‑person(b) Foodborne(c) Airborne(d) Waterborne(e) Bloodborne
____ salmonellosis____ hepatitis A____ psittacosis____ hepatitis B
Question 6.
Answer
B salmonellosis
A hepatitis A
C psittacosis
E hepatitis B
Question 7.
The Culex tarsalis mosquito is the vector in:
(a) Malaria
(b) Typhus
(c) Western equine encephalitis
(d) Yellow fever
Question 7.
Answer
(c) Western equine encephalitis
Question 8.
The A.I.D.S. (Acquired Immune Deficiency Syndrome) is due to a HIV infection. The mode of transmission for HIV infection is similar to:
(a) Hepatitis A
(b) Tuberculosis
(c) Typhoid
(d) Hepatitis B
(e) None of these
Question 8.
Answer
(d) Hepatitis B
Question 9.
Notification of infectious disease is the duty of:
(a) The attending physician
(b) A teacher or principal
(c) A nurse providing professional services
(d) The manager of a medical laboratory
(e) All of the above
Question 9.
(a) The attending physician
Question 10.With one exception, all of the following are
notifiable communicable disease under Saskatchewan public health legislation. The one exception is: (a) Food poisoning(b) Diphtheria(c) Measles(d) HIV infection(e) Pneumococcal pneumonia
Question 10.
Answer
(e) Pneumococcal pneumonia
Question 11.
Communicable disease control in a population may be brought about by:
(a) Reduction in size of disease reservoir
(b) Increasing host resistance
(c) Limiting transmission of disease
(d) Chemoprophylaxis
(e) All of the above
Question 11.
Answer
(e) All of the above
Question 12.A reduction in the size of the disease reservoir is basic to prevention of disease. Such a principle has been successfully applied to the control of:
(a) Hepatitis B (b) Gonorrhea(c) Syphilis(d) Salmonellosis(e) None of the above
Question 12.
Answer
(e) None of the above
Question 13.The most important cause of the decline in United States tuberculosis mortality rate from 194 per 100,000 in 1900 to 23 per 100,000 in 1950 was:
(a) Immunization(b) Chemotherapy(c) Environmental sanitation(d) Aging of the population(e) Improvement in general social
conditions
Question 13.
Answer
(e) Improvement in general social conditions
Question 14.Immunization, testing of herds and destruction of infected animals has been applied to the control of brucellosis. It is an example of infection control by:
(a) Interrupting the transmission of organisms
(b) Reducing host susceptibility(c) Reducing the size of the reservoir(d) All of these(e) None of these
Question 14.
Answer
(c) Reducing the size of the reservoir
Question 15.A child has been bitten by a dog. Which of the following factors
would you take into account in deciding what action to take?
(a) If the bite were on the head or neck
(b) The child provoked the animal (e.g. poke with a stick)
(c) The child knew the animal and its normal residence
(d) The dog has shown abnormal behaviour over the last 24 hours
(e) All of the above
Question 15.
Answer
(e) All of the above
Immunization
Immunization of Travellers Required Immunizations
Yellow fever Meningococcal disease Cholera
Recommended Immunizations Hepatitis A Typhoid Meningococcal disease Japanese encephalitis Cholera Influenza BCG
Vaccines Recommended for All Health Care Workers
Diphtheria and tetanus toxoidMeasles vaccinePolio vaccineRubella vaccineHepatitis B vaccine Influenza vaccine
Question 16.A child of 4 months of age has had its second dose of DPaT (Adsorbed) Vaccine. Mother reports that three hours after receiving the immunization, the child screamed for about 12 hours. She was unable to console him. For the third immunization in the series, you would use:
(a) DPaT Adsorbed(b) Diphtheria only(c) Tetanus only(d) Pertussis only(e) DT (Adsorbed)
Question 16.
Answer
(a) DPaT Adsorbed
Question 17.Which of the following is not a contraindication to the use of live vaccine?
(a) Pregnancy(b) Immunosuppression (drug induced)(c) Immunocompromised host (disease
induced)(d) History of allergy to house dust
Question 17.
Answer
(d) History of allergy to house dust
Question 18.Canadian provinces have introduced the adsorbed vaccine for many of their childhood immunizations. One of the main advantages of the adsorbed vaccine DPT are:
(a) It can be given subcutaneously(b) It has a longer lasting effect than the
plain vaccine(c) It can be taken intranasally(d) They are 100% effective(e) They cause fewer side effects
Question 18.
Answer
(e) They cause fewer side effects
Question 19.A 27 year old woman presents with a minor
wound caused while gardening. She has had no immunization since completing a full course of childhood immunizations. You would administer:
(a) DPaT vaccine (b) Tetanus and diphtheria toxoid (Td) (c) Tetanus toxoid alone (d) Tetanus immune globulin (e) None of the above
Question 19.
Answer
(b) Tetanus and diphtheria toxoid (Td)
Question 20.
Mortality rates in Canada for diphtheria have declined from 20/100,000 in 1921 to 0.02 in 1970. The most important cause for this was:
(a) Immunization
(b) Chemotherapy
(c) Environmental sanitation
(d) Aging of the population
(e) Improved standard of living
Question 20.
Answer
(a) Immunization
Question 21.Case fatality from diphtheria is as great now as 50 years ago. But there are fewer deaths from diphtheria in Canada because:
(a) Antitoxin is more easily available(b) The organism is sensitive to penicillin(c) Fewer cases of diphtheria occur now(d) There is better reporting of cases(e) Early diagnosis of diphtheria occurs
currently
Question 21.
Answer
(c) Fewer cases of diphtheria occur now
Question 22.The rubella vaccine currently used in Canada is a live vaccine which produces a good antibody response. Contra‑indications to its use are:
(a) Pregnancy(b) Infants whose mothers are
pregnant(c) Male interns working in obstetrics(d) All of the above(e) None of the above
Question 22.
Answer
(a) Pregnancy
Question 23.
Which of the following diseases has a non-human reservoir?
(a) Typhoid
(b) Shigellosis
(c) Smallpox
(d) Salmonellosis
(e) None of the above
Question 23.
Answer
(d) Salmonellosis
Question 24.In a national vaccine trial, the incidence rate of poliomyelitis was 16/100,000 for vaccinated children and 57 for children who received the placebo. The effectiveness was, therefore:
(a) 45%(b) 70%(c) 72%(d) 79%(e) 87%
Question 24.
Answer
(c) 72%
Question 25.Following a bite from a skunk in an area where rabies is endemic, the physician should:
(a) Ensure immediate washing and flushing of the wound, preferably with soap or
detergent(b) Administer rabies immune globulin
immediately(c) Administer rabies human diploid cell
vaccine immediately(d) Report the case to public health(e) All of the above
Question 25.
Answer
(e) All of the above
Question 26.Chronic carriers may be important in infectious disease epidemics. Which of the following diseases can produce a chronic carrier state?
(a) Smallpox(b) Hepatitis B(c) Hepatitis A(d) Pertussis(e) None of the above
Question 26.
Answer
(b) Hepatitis B
Question 27.People over 65 years of age have a higher incidence of tuberculosis than do young adults because:
(a) Their diets are poorer(b) They live under more crowded
conditions(c) They were exposed to more
tuberculosis infection in childhood(d) Their disease is more often
reported(e) None of the above
Question 27.
Answer
(c) They were exposed to more tuberculosis infection in
childhood
Question 28.The number and percent distribution of tuberculosis deaths by age for white males in the U.S.,1955 is as follows:
% OF ALL DEATHS AGE DEATHS IN EACH AGE GROUP under 1 21 0.2 1‑ 4 32 0.1 5‑14 14 0.2 15‑24 92 1.0 25‑34 470 5.2 35‑44 993 11.1 45‑54 1858 20.7 55‑64 2246 25.1 65‑74 2152 24.0 75‑84 913 10.2 85+ 167 1.9 8958 100%
Question 28.The inference that tuberculosis mortality rates in extreme old age are lower than they are in persons who are not so old is:
(a) Correct(b) Incorrect because of failure to
distinguish between incidence and prevalence
(c) Incorrect because a percentage distribution is used when a rate is
required to support the inference(d) Incorrect because of failure to
recognize a possible cohort phenomenon(e) Incorrect because there is no control or
comparison group
Question 28.
Answer
(c) Incorrect because a percentage distribution is used when a
rate is required to support the inference
Question 29.Typhoid fever is characterized by the following:
(a) Domestic animals are reservoirs of S. Typhi(b) Less than 1% of typhoid fever patients will still
discharge typhoid bacilli three months after the onset of their disease
(c) Cholecystectomies are recommended for typhoid patients who are still carrying the typhoid bacillus three months after onset of the illness
(d) Typhoid vaccine is not an important means of controlling typhoid fever in developed
countries
Question 29.
Answer
(d) Typhoid vaccine is not an important means of controlling typhoid fever
in developed countries
Question 30.
The screening test for HIV infection used by the Red Cross Blood Transfusion Services tests for:
(a) HIV antigen
(b) HIV antibody
(c) T Helper T Suppressor ratio
(d) A combination of the above
Question 30.
Answer
(b) HIV antibody
Question 31.
What is the estimated risk of a child born to an HIV positive mother becoming HIV positive?
(a) Nil
(b) 100%
(c) 20 - 25%
(d) 80 - 90%
Question 31.
Answer
(c) 20 - 25%
Question 32.
B.C.G. vaccination is an example of immunization using:
(a) A live virus vaccine
(b) A killed vaccine
(c) A live attenuated bacillus
(d) A killed bacterial culture using a bacterial product
Question 32.
Answer
(c) A live attenuated bacillus
Question 33.
Pediculosis pubis is an infestation by the crab louse. It is commonly found in all but one of the following areas:
(a) Pubic hair(b) Perianal hairs(c) Scalp(d) Eyelashes(e) Axillae
Question 33.
Answer
(c) Scalp
Question 34.
Which of the following disease epidemics can be controlled by immunization of the population?
(a) Typhoid(b) Polio(c) Cholera(d) Cryptosporidiosis(e) None of the above
Question 34.
Answer
(b) Polio
Question 35.In a point source epidemic all cases will present:
(a) Within the infectious period of the source
(b) Within the range of minimum and maximum incubation periods of
the disease(c) Within the minimum incubation period of
the disease(d) Within the maximum incubation period
of the disease(e) At one point in time
Question 35.
Answer
(b) Within the range of minimum and maximum incubation periods of the disease
Question 36.Which of the following statements are not true about the
West Nile virus?(a) The West Nile virus can be transmitted
by culex mosquitos.(b) Human transmission of West Nile virus
is possible(c) The main reservoir for West Nile virus is
horses(d) 80% of people infected with West Nile
virus are asymptomatic(e) Crows play an important part in the
surveillence of West Nile virus
Question 36.
Answer
(c) The main reservoir for West Nile virus is horses
Question 37.It has been reported that approximately 13% of refugees from south east Asia have a positive test for Hepatitis B surface antigen (HBsAg). However, other groups in our community are recognized as having rates equal to or greater than those of the south east Asian refugee. Such groups would be:
(a) Physicians(b) Injection drug users(c) Microbiologists(d) Physiotherapists(e) Laboratory technicians ‑ chemical
pathology
Question 37.
Answer
(b) Injection drug users
Question 38.The control of epidemics by isolation of cases is of little value if the disease produces a large number of sub-clinical infections. Examples of such a diseases would be:
(a) Tuberculosis(b) Infectious Hepatitis A(c) Polio(d) Cholera(e) All of the above
Question 38.
Answer
(e) All of the above
Question 39.The following represents the epidemic curve for 24 cases of Hepatitis A.
It is an example of:(a) Person to person
spread(b) Possible point source epidemic(c) A recurrent food borne outbreak(d) None of the above
Question 39.
Answer
(b) Possible point source epidemic
Question 40.Examine the graph of an epidemic curve. The cases in this epidemic all have gastrointestinal complaints. Which of the following is the most likely cause of the epidemic?
(a) Staphylococcal food poisoning
(b) Salmonella
(c) Influenza‑like virus
(d) A spill of a toxic chemical into the area's water supply
(e) Pollution of the air by a toxic chemical from a
nearby paint factory
Question 40.
Answer
(b) Salmonella
Question 41.In 1967 WHO started a program of smallpox eradication. This was successful because:
(a) Sub‑clinical cases occur commonly(b) Humans constituted the only
reservoir(c) Vaccine effectiveness is not easily
measured(d) 100% vaccination has been
possible in the developing countries
Question 41.
Answer
(b) Humans constituted the only reservoir
Question 42.Which of the following factors contributed to the global eradication of smallpox?
(a) There were no sub-clinical cases(b) Immunization was highly effective(c) Isolation of clinical cases was
effective in preventing transmission(d) Action was organized at an
international level(e) All of the above
Question 42.
Answer
(e) All of the above
Question 43.
An adult patient of yours is going to Central Africa. What immunization(s) should be considered?
(a) Gonorrhea (b) Malaria (c) Yellow fever(d) West Nile virus(e) All of the above
Question 43.
Answer
(c) Yellow fever
Question 44.
For adult travellers from Canada to malarious areas, which of the following would not be considered for prophylactic use?
(a) Mefloquine
(b) Chloroquine
(c) Malarone
(d) Doxycycline
(e) All of the above
Question 44.
Answer
(e) All of the above
Question 45.
A certificate for yellow fever is required by one of your patients who is travelling to South America. After primary vaccination the certificate will be valid after:
(a) 3 days
(b) 6 days
(c) 10 days
(d) 14 days
Question 45.
Answer
(c) 10 days
Question 46.
Maximum time from intercourse with a person infected with syphilis to the development of a primary chancre is:
(a) Three weeks(b) Three months(c) Six months(d) One year(e) None of the above
Question 46.
Answer
(b) Three months
Question 47.
Chlamydia trachomatis infection has been associated in females with:
(a) Chronic pelvic pain
(b) Infertility
(c) Pelvic inflammatory disease
(d) Ectopic pregnancy
(e) All of the above
Question 47.
Answer
(e) All of the above
Food Poisoning
Food Poisoning- causes Staph aureus E. coli enteritis Salmonella Shigella Campylobacter Cholera Botulism Mushroom poisoning Listeria Bacillus cereus Fish poisoning Yersinia
Question 48.Bacillus cereus is a recognized agent of food poisoning. The food most likely to be contaminated with this agent is:
(a) Hamburger meat (b) Shellfish (c) Rice(d) Potato Salad (e) Chicken(f) Home-made canned vegetables
Question 48.
Answer
(c) Rice
Questions 49-54.Match each of the following with the food listed.
49. B. cereus 50. E. coli (0l57)51. Demoic Acid 52.
Staphylococcus 53. Salmonella 54. Clostridium
botulinum
(a) Hamburger meat (b) Shellfish (c) Rice(d) Potato Salad (e) Chicken(f) Home-made canned vegetables
Questions 49-54.
Answers
49- c
50- a
51- b
52- d
53- e
54- f
Question 55.Within 30 minutes of eating a bouillabaisse containing tuna, mackerel and shellfish, the subject became flushed, developed urticaria and abdominal cramps. The most likely cause was:
(a) Scrombotoxin (histamine) (b) Staphylococcal toxin (c) Clostridrium perfringens(d) Salmonella(e) Botulinum toxin (f) Shigella (g) Campylobacter
Question 55.
Answer
(a) Scrombotoxin (histamine)
Question 56.
66. One method of pasteurisation is to hold the product at 71.6oC for 15 seconds. This treatment can be relied on to:
(a) Kill spoilage organisms only
(b) Kill most pathogenic bacteria
(c) Sterilize the product
Question 56.
Answer
(b) Kill most pathogenic bacteria
Question 57.Which of the following statements about scabies are true? (Check any number)
(a) Now an uncommon condition (b) Always associated with poor personal
hygiene (c) Characterized by relentless itching,
more intense by day. (d) Distribution of rash characteristically
between fingers, around wrists, and in flexures and buttocks.
(e) Spread by personal contact (f) Persons who are re-infected develop
symptoms within 1-4 days
Question 57.
Answer
True- d, e, f
Questions 58-67.
An outbreak of illness from West Nile virus infection took place in the northeastern United States between July and October, 2001.
For each of the numbered situation below, select the most appropriate term from the following lettered options. Each option can used once, more than once or not at all.
A. EpidemicB. Sentinel caseC. Incidence rateD. RiskE. False- positiveF. False- negativeG. Risk factorH. Prognostic factorI. Natural historyJ. Case fatalityK. Median survivalL. Randomized controlled clinical trialM. Cohort studyN. Case-control study
Question 58.
Persons with fever/headache were ten times more likely than others to have serum evidence of WNV. Fever/ headache is best described as
A. EpidemicB. Sentinel caseC. Incidence rateD. RiskE. False- positiveF. False- negativeG. Risk factorH. Prognostic factorI. Natural historyJ. Case fatalityK. Median survivalL. Randomized controlled clinical trialM. Cohort studyN. Case-control study
Question 58.
G. Risk factor
Question 59.
Among Staten Island residents 2.5 per 100,000 persons developed severe WNV neurologic disease during this time period. This measure best described as
A. EpidemicB. Sentinel caseC. Incidence rateD. RiskE. False- positiveF. False- negativeG. Risk factorH. Prognostic factorI. Natural historyJ. Case fatalityK. Median survivalL. Randomized controlled clinical trialM. Cohort studyN. Case-control study
Question 59.
C. Incidence rate
Question 60.
WNV has occurred for the first time in the United States the preceding year. This unusual pattern of occurrence is best described as
A. EpidemicB. Sentinel caseC. Incidence rateD. RiskE. False- positiveF. False- negativeG. Risk factorH. Prognostic factorI. Natural historyJ. Case fatalityK. Median survivalL. Randomized controlled clinical trialM. Cohort studyN. Case-control study
Question 60.
A. Epidemic
Question 61.
A person who has the symptoms consistent with severe WNV neurologic disease, but does not have definitive serologic evidence of infection
A. EpidemicB. Sentinel caseC. Incidence rateD. RiskE. False- positiveF. False- negativeG. Risk factorH. Prognostic factorI. Natural historyJ. Case fatalityK. Median survivalL. Randomized controlled clinical trialM. Cohort studyN. Case-control study
Question 61.
E. False-positive
Question 62.
Two of 21 patients with severe WNV neurologic disease died. This best described by
A. EpidemicB. Sentinel caseC. Incidence rateD. RiskE. False- positiveF. False- negativeG. Risk factorH. Prognostic factorI. Natural historyJ. Case fatalityK. Median survivalL. Randomized controlled clinical trialM. Cohort studyN. Case-control study
Question 62.
J. Case fatality
Question 63.
The first person with severe WNV neurologic disease died. This is best described by
A. EpidemicB. Sentinel caseC. Incidence rateD. RiskE. False- positiveF. False- negativeG. Risk factorH. Prognostic factorI. Natural historyJ. Case fatalityK. Median survivalL. Randomized controlled clinical trialM. Cohort studyN. Case-control study
Question 63.
B. Sentinel case
Question 64.
Clinical outcome of severe WNV nerologic disease was substantially worse for elderly patients. Advanced age is best described as
A. EpidemicB. Sentinel caseC. Incidence rateD. RiskE. False- positiveF. False- negativeG. Risk factorH. Prognostic factorI. Natural historyJ. Case fatalityK. Median survivalL. Randomized controlled clinical trialM. Cohort studyN. Case-control study
Question 64.
H. Prognostic factor
Question 65.
A study of antiviral agents is conducted for the treatment of severe WNV neurologic disease in which treatment assignments to individual patients are made by chance
A. EpidemicB. Sentinel caseC. Incidence rateD. RiskE. False- positiveF. False- negativeG. Risk factorH. Prognostic factorI. Natural historyJ. Case fatalityK. Median survivalL. Randomized controlled clinical trialM. Cohort studyN. Case-control study
Question 65.
L. RCT
Question 66.
A study is conducted comparing prior use of mosquito repellent by persons with and without severe WNV neurologic disease. This best described as
A. EpidemicB. Sentinel caseC. Incidence rateD. RiskE. False- positiveF. False- negativeG. Risk factorH. Prognostic factorI. Natural historyJ. Case fatalityK. Median survivalL. Randomized controlled clinical trialM. Cohort studyN. Case-control study
Question 66.
N. Case-control study
Question 67.
A study is conducted in which the rates of subsequent WNV infection are compared in communities with and without mosquito abatement programs. This best described as
A. EpidemicB. Sentinel caseC. Incidence rateD. RiskE. False- positiveF. False- negativeG. Risk factorH. Prognostic factorI. Natural historyJ. Case fatalityK. Median survivalL. Randomized controlled clinical trialM. Cohort studyN. Case-control study
Question 67.
M. Cohort study