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Bugs, Drugs, and Thugs:
Case Studies in Virology
SAFMLS WORKSHOP
12 FEB 2008
DAVID G. WATSON, MAJ, USAF, BSC
Bugs, Drugs, and Thugs
Infectious Disease Case Study 1
A 9-year-old black female, a recent émigré from Haiti, came to a Florida
Emergency Room because of a fever, headache, sore throat and mild cough.
Her parents say that she has been sick for 2-3 days. You note that she has a
runny nose and a mild conjunctivitis. Her temperature is 39, pulse rate 110
beats/min, blood pressure 90/60 mm Hg, and respiratory rate 42/min. You note
that her pharynx is very red and that she also has some bright red spots with
white centers on her buccal mucosa. Her chest is clear. You take a throat swab
and send the child home instructing the parents to return with the child tomorrow
when you will have the results of the throat culture.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 1
Question 1
The throat swab is most commonly used to diagnose?
A) whooping cough
B) influenza
C) strep throat
D) measles
E) diphtheria
Answer
C) strep throat
This is the most common use. The swab is streaked on blood agar. If beta
hemolytic colonies are seen the bacteria are Group A or pathogenic
Streptococci.
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Infectious Disease Case Study 1
Question 2
On the whole, would you agree with the decision to send
this child home with no treatment or instructions for care?
A) Yes, because even if she had a strep throat, tomorrow is
soon enough to start treatment and viral diseases can't be cured.
B) No, because she may not come back and miss treatment for a
disease that could result in rheumatic fever.
C) No, because she had a highly communicable disease that you
should have recognized.
D) Both B and C have some merit.
Answer
D) Both B and C have some merit.
Both the fact that she might not come back if she starts to feel better and the
fact that she might have a communicable disease should weigh in your answer.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 1
There are no beta hemolytic colonies seen on the blood agar plate the next day.
The child does return and when you examine her again you notice a rash behind
her ears and on her face. Careful examination of the rash shows that it is
maculopapular.
Question 3
The absence of beta hemolytic colonies on the blood agar plate means?
A) the child does not have scarlet fever
B) the child does not have rheumatic fever
C) the child does not have Rocky Mt. Spotted fever
D) the child has measles
E) the child has German measles
Answer
A) the child does not have scarlet fever
Scarlet fever is caused by Group A beta hemolytic streptococci -- it can be
thought of as a strep throat with a rash. This child would have beta hemolytic
colonies on blood agar from the throat swab if she had scarlet fever.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 1
Question 4
The differential diagnosis for a child with a rash is quite large.
Measles, German measles and Rocky Mt. spotted fever should be
considered. What are some other agents that can cause a rash?
A) B19, HHV3, Bordetella
B) chlamydia, Coxsackievirus, EEEV
C) hantavirus, flu virus, HHV3
D) Treponema pallidum, B19, Coxsackievirus
Answer
D) Treponema pallidum, B19, Coxsackievirus
These should all be included. T. pallidum causes syphilis and secondary syphilis
presents with a rash.
A good differential diagnosis for this child's disease would be measles, German
measles, Rocky Mt. spotted fever, fifth disease, Coxsackievirus infection,
secondary syphilis. You know its not scarlet fever because of the throat culture.
A few parasitic diseases, that a recent emigrant could have, also have rashes.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 1
Question 5
You ask the parents if they have seen any ticks on the child or if she had been
anywhere that she could have been bitten by a tick. This would bear on the
diagnosis of which of the following?
A) measles
B) secondary syphilis
C) fifth disease
D) Rocky Mt. spotted fever
E) Coxsackievirus infection
Answer
D) Rocky Mt. spotted fever
This rickettsial disease is spread by ticks.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 1
Question 6
What in the world causes fifth disease?
A) an adenovirus
B) a parvovirus
C) a poxvirus
D) a herpesvirus
E) a picornavirus
Answer
B) a parvovirus
It’s called B19. B19 is a virus that commonly
infects humans; about 50% of all adults have
been infected sometime during childhood or
adolescence. Parvovirus B19 infects only
humans.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 1
Question 7
B19 usually causes a very mild disease. Two groups
of people for whom it can be serious, however, are?
A) teenagers and pregnant women
B) pregnant women and sickle-cell anemics
C) the sexually promiscuous and drug addicts
D) alcoholics and asplenics
E) smokers and alcoholics
Answer
B) pregnant women and sickle-cell anemics
Primary infection in pregnant women is very serious
and can result in death of the fetus. In patients with
sickle-cell disease, the virus can initiate a transient
aplastic crisis.
Typical giant proerythroblast seen in
B19-associated pure red cell aplasia
with highly uncondensed chromatin
and pale purple intranuclear
inclusions (bone marrow aspirate,
hematoxylin-eosin, x1000).
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 1
Question 8
What should have alerted you to
the possibility of measles?
A) the conjunctivitis
B) the Koplik spots
C) the runny nose (coryza)
D) the cough
E) all of the above
Answer
E) all of the above
The combination of the three C's (cough, coryza, conjunctivitis)
and Koplik spots should have been a red flag.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 1
Question 9
Why is it so important to diagnose measles?
A) it can be cured
B) the complications can be prevented
C) the child needs to be vaccinated against measles
D) pregnant women exposed to the child need to
have abortions
E) all unvaccinated contacts need to be protected
Answer
E) all unvaccinated contacts need to be protected
Measles is a very serious and highly communicable
disease and all unvaccinated contacts need to
receive the vaccine. If contacts are less than 1 yr.
old or immunocompromised, hyperimmune serum
globulin is recommended.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 1
Question 10
How is measles normally prevented?
A) DPT vaccine
B) MMR vaccine
C) killed viral vaccine
D) live oral vaccine
E) measles vaccine is no longer needed
Answer
B) MMR vaccine
This is measles, mumps and rubella
– all are live attenuated viruses.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 1
Question 11
When is the MMR vaccine usually given?
A) 2, 4, 6, 15 months and 4-6 years.
B) 2, 4, 15 months and 4-6 years.
C) 2, 4, 6, 15 months.
D) 15 months and 4-6 years.
Answer
D) 15 months and 4-6 years.
If you had attended my SAFMLS workshop
last year on Vaccines, you would have known this!
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 1
Question 12
Why is the MMR vaccine given so much later than the other childhood vaccines?
A) the live viruses are dangerous until the children have some natural immunity.
B) the vaccines don't work due to maternal antibody before this time.
C) the immune system is not mature enough to make antibodies before this time.
D) cellular immunity that is needed will not develop before this time.
E) the vaccines can cause severe complications in children under 1 yr. old.
Answer
B) the vaccines don't work due to maternal antibody before this time.
The maternal antibody neutralizes the vaccine virus.
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Infectious Disease Case Study 1
Question 13
What is/are the complication(s) of measles?
A) SSPE (subacute sclerosing panencephalitis)
B) viral pneumonia
C) bacterial pneumonia
D) encephalitis
E) all of the above
Answer
E) all of the above
They can all occur and all be very serious!
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 1
Question 14
How can measles be confirmed?
A) heterophile antibodies
B) anti-measles IgG
C) anti-measles IgM
D) growth of the virus in tissue culture
E) all of the above
Answer
C) anti-measles IgM
You could also look for measles
virus antigen using fluorescent
antibodies to the virus.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 1
A measles antigen detection assay tested positive for the measles virus. You send
the child home but tell the parents to keep her isolated. Eight other children and
four adults in the same house were given measles vaccine. One baby was given
hyperimmune serum globulin. Twenty neighborhood children that had never been
immunized were also immunized.
Question 15
How is it that so many of this child's contacts were not previously vaccinated?
A) the vaccine is only available in the USA and all the others were immigrants.
B) the vaccine is expensive and only purchased by those who can afford it.
C) the lowest socioeconomic classes have the poorest vaccination rates.
D) the perceived high incidence of reactions to the vaccine make it very unpopular.
Answer
C) the lowest socioeconomic classes have the poorest vaccination rates
They often "fall through the cracks," as it were. They either have not been taught
that vaccinations are important, they don't know where to go to get them, or they
don't have the money, time, or energy to do it.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 1
The sick child appeared to be recovering but after 10 days had a resurgence of
fever, severe headaches, and seizures.
Question 16
This new development?
A) is normal in the course of measles
B) signals measles pneumonia
C) occurs in about 0.1% of measles cases
D) is most likely unrelated to the measles
E) is SSPE
Answer
C) occurs in about 0.1% of measles cases
Measles encephalitis occurs in 1 out of every 1000 or 2000 cases.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 1
Outcome: The child was hospitalized and given supportive care. Although many
children suffer neurological deficits after measles encephalitis, this child recovered
and was left with no sequelae.
She grew up and, fondly remembering the kindness of the doctors who cared for
her, went to Medical School at the University of Florida.
Dr. Ertha Pascal-Trouillot later returned to her
native country and, in 1991, became the first,
and only, woman president of Haiti.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 2
A 69-year-old male citizen of Mexico who arrived a month ago to visit his
son and daughter-in-law in Florida for the summer, was evaluated at an
urgent-care center for a 3-day history of increasing pain in his left jaw,
chest and shoulder. He also complained of sore throat, anxiety, insomnia,
nausea and vomiting. He said he had received a spider bite on his left jaw
and that the pain had started after that. His daughter-in-law commented
that he had been somewhat confused since arriving in Florida and that she
couldn't remember a spider bite.
He was transferred to the hospital and treated for chest pain, but
evaluation ruled out cardiac disease and pneumonia. He rejected all oral
fluids and continued to complain of the spider bite.
He was sent to the mental health unit where he was noted to be anxious
and have impaired memory. He was diagnosed with anxiety disorder and
given tranquilizers and discharged.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 2
Question 1
Insects and other arthropods (ticks) are known to transmit a number of
diseases of bacterial, viral, and parasitic origin. Are spiders implicated in
the transmission of any common infectious diseases?
A) yes
B) no
Answer
B) no
Certainly none that are common.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 2
Question 2
Which of the following groups of diseases are
all transmitted by insects or ticks?
A) yellow fever, Lyme disease, typhoid fever
B) syphilis, gonorrhea, AIDS
C) Rocky Mt. spotted fever, typhus, viral encephalitis
D) rabies, viral encephalitis, Lyme disease
E) African sleeping sickness, giardiasis, plague
Answer
C) Rocky Mt. spotted fever, typhus, viral encephalitis
These come from, respectively, ticks, fleas,
and mosquitoes.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 2
Question 3
Which of the following microbes can cause chest pain?
A) influenza virus
B) Streptococcus pneumoniae
C) Coxsackievirus B
D) rabies virus
E) all of the above
Answer
E) all of the above
But by different mechanisms.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 2
Question 4
Which of the following groups of infectious diseases cause neurological
changes?
A) cat scratch disease, measles, meningitis
B) AAV infection, mycoplasma pneumonia, tetanus
C) meningitis, viral encephalitis, rabies
D) chicken pox, measles, rotavirus infection
E) gonorrhea, syphilis, Herpes infection
Answer
C) meningitis, viral encephalitis, rabies
All these are infections of the brain or brain
covering and all can cause some type of
neurological change.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 2
Two days later the gentleman returned in acute distress. He complained of a
headache and also a terrible thirst. He had a fever of 39.6, hypersalivation,
inability to swallow, and a staggering gait.
As the technician tried to take a routine blood sample, the man tried to bite
her. The doctors and nurses stated that they had ever seen anything quite like
it.
However, a nurse from the Philippines thought she recognized the disease
immediately.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 2
Question 5
What rare disease did the nurse
think she recognized?
A) encephalitis
B) leishmaniasis
C) meningitis
D) cysticercosis
E) rabies
Answer
E) rabies
The hydrophobia, hypersalivation, and biting behavior are all almost
unique to rabies. It is endemic in the Philippines so the nurse might
well recognize it.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 2
The doctors decided, instead, to do a spinal tap to diagnose the man's disease.
Question 6
What diseases might they be considering when
they ordered the spinal tap?
A) meningitis
B) encephalitis
C) both A and B
D) neither A nor B
Answer
C) both A and B
Both are possibilities.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 2
Question 7
What are the most common causes of acute meningitis?
A) Haemophilus influenzae, Neisseria meningitidis, and Streptococcus pneumoniae
B) Listeria monocytogenes, Escherichia coli, and Streptococcus agalactiae
C) measles, mumps, and herpes viruses
D) cryptococcus and histoplasmosis fungi
E) enteroviruses
Answer
A) Haemophilus influenzae, Neisseria meningitidis, and Streptococcus pneumoniae
These three bacteria are the most frequent causes of meningitis.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 2
The lab results on the blood and CSF evaluation showed the following:
CSF: 2 red blood cells, 1 neutrophil, and 9 lymphocytes/ml
CSF glucose: 67 mg/dL (normal 40-80)
CSF protein: 163 mg/dL (normal 15-45)
CSF gram stain: negative
Blood count: 12,100 leukocytes/ml
Blood glucose: 98 mg/dL
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 2
Question 8
The CSF glucose and protein profile is most characteristic of?
A) bacterial infection
B) viral infection
C) fungal infection
Answer
B) viral infection
CSF protein is slightly high and glucose is normal. This is indicative of a viral
infection. The lymphocytes also are indicative of a virus.
Based on the analysis of the CSF and the negative Gram stain, the doctors
decided he had a viral encephalitis.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 2
Question 9
EEEV, WEEV, VEEV and St. Louis Encephalitis virus all cause encephalitis.
How are these viruses transmitted?
A) from horses
B) by bird droppings
C) by mosquitoes
D) by mosquitoes or ticks
E) via the respiratory route from other infected humans
Answer
C) by mosquitoes
The mosquitoes transmit it from the birds to humans.
Note: Two types of encephalitis are transmitted by ticks, but not the four listed here.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 2
While in the hospital, his condition rapidly deteriorated, and even though he was
placed on respiratory support he died the next day.
Brain specimens were sent to the Department of Pathology where rabies was
diagnosed on the basis of Negri bodies and detection of rabies antigen by a
positive reaction after staining with fluorescent anti-rabies antibody.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 2
Subsequent correspondence with his family in Mexico revealed that a puppy
had bitten him on the neck two weeks before he came to Florida (i.e., about
six weeks ago). He had thoroughly cleaned the bite site and because it was
not deep, he had not worried about it.
The family stated that the puppy had
been taken to another neighborhood
and abandoned because it had tried
to bite both humans and other animals.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 2
Question 10
What behavior occurs in rabies that does not occur in other viral encephalitides?
A) excessive salivation
B) hydrophobia
C) biting (snapping)
D) all of the above
E) none of the above
Answer
D) all of the above
Yes, they all do.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 2
Question 11
How did the man get rabies?
A) the spider bite
B) the puppy bite
C) the drinking water in Mexico
D) via the respiratory route
E) from a corneal transplant
Answer
B) the puppy bite
Any mammal can transmit rabies, but dogs are a very common source, especially
in underdeveloped countries. In Florida it is usually raccoons. People have also
gotten rabies from a corneal transplant. Several times in fact. But the patient didn't
have a corneal transplant that we know of. Furthermore, there is usually periorbital
pain with corneal-transmitted rabies.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 2
Question 12
How could the man's rabies have been prevented?
A) vaccination prior to the bite
B) vaccination after the bite
C) prophylactic interferon after the bite
D) hyperimmune globulin
E) B and D
Answer
E) B and D
Post-exposure vaccination works with rabies because of the long incubation period.
However, hyperimmune serum globulin is also given in the case of a bite by a
possibly rabid animal.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 2
Question 13
Who discovered that rabies could be prevented by post-exposure vaccination?
A) Salk
B) Sabin
C) Jenner
D) Koch
E) Pasteur
Answer
E) Pasteur
It was almost 100 years after the world's first
vaccine for humans (Jenner's smallpox vaccine)
that Pasteur developed the second--rabies.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 2
Question 14
What other viruses are in the same
family as rabies?
A) EEEV
B) Lyme disease virus
C) California Encephalitis virus
D) Norwalk virus
E) none of the above
Answer
E) none of the above
Vesicular Stomatitis virus (VSV) is in the same family as rabies, the rhabdoviruses,
but it mostly just causes disease in cows. It is used, however, as a model to study
rhabdoviruses.
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Bugs, Drugs, and Thugs
Infectious Disease Case Study 2
Outcome: Twenty health care workers who had helped care for the
gentleman were given rabies vaccination. His son and daughter-in-law
also received it. None of the known contacts became sick.
Health authorities in Mexico were notified and administered vaccine to 4
children who had reportedly played with the dog. The abandoned puppy
was never found, but they identified a 10-block area in which all owned
dogs were vaccinated and all strays were destroyed. No other cases
were reported.
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Bugs, Drugs, and Thugs
Infectious Disease Case Review Scorecard
So…. How did you do? Add up your correct # of answers.
29 - 30 Correct: You must have your Ph.D.!
27 - 28 Correct: You must be working on your Masters Degree!
25 - 26 Correct: You must be a Lab Technician
22 - 24 Correct: You must be an Administrator
19 - 21 Correct: You must be a Lab Commander
16 - 18 Correct: You must be doing a lot of PT!
15 or less Correct: You must be a Physician!
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