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Self Assessment Questions

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1. A 35-year-old workman is evaluated in the emergency department because of acute shortness of breath of 1-hour duration that is unresponsive to inhaled albuterol. He was well until this morning when he was assigned to clean the outside entrance to an office complex where a suspicious white powder had been discovered the day before. He wore a paper facemask and latex gloves. He mixed ammonia and bleach and used a pressure washer to clean the sidewalk. After a few minutes, he developed burning in his eyes and throat, and shortness of breath and he was taken by ambulance to the emergency department.

Which of the following is the most likely cause of his symptoms?

A. Inhalational anthrax
B. Chloramine gas inhalation
C. Carbon monoxide poisoning
D. Anaphylactic reaction to latex.

Answer

2. A 43-year-old man is evaluated in the emergency department because of dyspnea. He was one of several people exposed to an unknown gas released in a subway station. Immediately following exposure to the gas, the victims complained of headache, nausea and vomiting, diaphoresis, and shortness of breath.

The patient is drenched in sweat, drooling and tearing, and sitting upright, gasping for air. Vital signs are: BP 90/60 mmHg, pulse 45/min, and respiratory rate 24/minute. Pupils are 2 mm and non-reactive. Lung examination reveals diffuse wheezing, and heart sounds are slow but regular. He suddenly becomes too weak to remain sitting, falls back in bed, and appears ashen.

Which of the following interventions should be instituted first?

A. Intravenous atropine and 2-pralidoxime chloride (2-PAM)
B. Albuterol and ipratropium via nebulizer
C. Intravenous cyanide antidote kit
D. Subcutaneous scopolamine.

Answer

3. A 23-year-old grounds keeper for a university in Michigan is evaluated because of a series of ulcerating nodules on his right forearm. The first nodule appeared five days ago and since that time two more nodules just proximal to the first nodule have appeared. Yesterday, the first second nodule developed small ulcers. The ulcers and nodules are mildly painful. He reports having a low-grade fever, but otherwise is in good health. He has not traveled outside of the Midwest.

On physical examination, his temperature is 99°F (37.2° C ). There are a series of nodules arranged in a linear pattern extending proximally from the mid-volar aspect of the right forearm to the elbow. The distal nodule is the largest, measuring 3x 2 cm and it and the subsequent nodule are ulcerated, showing a red granular base. There are tender, enlarged lymph nodes in the right axilla.

Which of the following is the most likely diagnosis?

A. Cutaneous anthrax
B. Sporotrichosis
C. Cutaneous leshmaniasis
D. Tularemia
E. Plague

Answer

4. A 37-year old, previously healthy postal worker in New Jersey is evaluated because of an enlarging sore on his right arm for 10 days. He denies trauma to the arm. The sore began as a painless, itchy papule that enlarged over one to two days, with small blisters forming on top of the papule that filled with clear fluid. As the blisters enlarged, extensive swelling developed around the sore. The blister broke down, forming a painless ulcer covered by a black scab. His symptoms include low-grade fever and malaise. He has not traveled outside of the mid-Atlantic area.

On physical examination the patient is not in any obvious distress. Temperature is 99° F (37.2° C). There is a 3 cm ulcer located on the upper, outer aspect of the right arm. A black, adherent eschar covers the ulcer. The ulcer and eschar are surrounded by extensive non-pitting edema. Lymphadenopathy is present in the right axilla.

Which of the following is the most likely diagnosis?

A. Cutaneous anthrax
B. Cat-scratch disease
C. Tularemia
D. Herpes simplex infection
E. Streptoccocal adenitits

Answer

5. Two brothers, ages 8 and 9 years, are evaluated in the office for fever and a pruritic skin rash. The boys were in their usual state of good health until yesterday. Within 3 hours of each other, they developed a rash that began on the face and has since become generalized. They were at birthday party 12 days ago and four other children who attended the party have developed a similar illness.

The boys appear well, but are uncomfortable due to itching. The boys each have a temperature of 99.2° F (37.3° C), but otherwise the vital signs are normal. Each child has a generalized eruption that consists of a thin-wall superficial vesicle on an erythematous base. The greatest concentration of vesicles is on the trunk, with fewer on the distal extremities. Many of the vesicles on the thorax have become pustular, and others are scabbed over.

Which of the following is the most likely diagnosis?

A. Chickenpox
B. Hand-foot-mouth disease
C. Disseminated herpes zoster
D. Smallpox

Answer

6. A previously healthy 16-year-old boy is evaluated in the office for dysphagia. Starting this morning he had difficulty swallowing, with fluid regurgitating out of his nose when he tried to swallow milk. He also reported having "double-vision" while reading the morning newspaper.

On physical examination, he is afebrile, his blood pressure is 120/70 mm Hg, and pulse is 70/min. He has bilateral ptosis and enlarged, sluggishly reactive pupils. The mouth is dry and the pharynx is injected. Muscle strength is good with normal deep tendon reflexes, and there are no sensory changes. The mental status examination is unremarkable.

A patient with similar symptoms was evaluated yesterday. This patient was found to have diplopia, dysarthria, dysphonia, and dysphagia as well as hypotonia of the neck muscles.

Which of the following is the most likely diagnosis?

A. Botulism
B. Guillain-BarreŽ polyradiculopathy
C. Myasthenia gravis
D. Poliomyelitis

Answer

7. A previously healthy 23-year-old woman residing in Washington DC is admitted to the hospital with a 2-day history of cough, substernal chest pain, fever (40°C), headache, chills, rigors, myalgias, coryza, and sore throat. On chest x-ray, she has patchy, nodular infiltrates and a pleural effusion. The sputum reveals numerous gram-negative coccobacilli. Despite empiric treatment with a beta-lactam antibiotic, she continues to deteriorate over the next 48 hours. On the second hospital day, three of her co-workers are admitted to the hospital with similar symptoms. The possibility of a deliberate epidemic is considered, and the differential diagnosis is broadened to include inhalational anthrax, pneumonic plague, and inhalation tularemia.

Which of the following communications to the public health system is most appropriate?

A. Immediately inform the Centers for Disease Control and Prevention (CDC)
B. Confirm the diagnosis and inform the CDC
C. Immediately inform the local or state public health organization
D. Confirm the diagnosis and inform the local or state public health organization

Answer

8. A 37-year-old woman from New Mexico is admitted to the hospital with a rapidly progressive bronchopneumonia. She was feeling well until 2 days ago when she developed fever, cough, hemoptysis, dyspnea, and chest pain. Within hours of admission to the hospital, gram-negative bacilli are identified in a sputum sample. Two days after admission she is placed on a ventilator to manage respiratory failure.

Which of the following most strongly suggests the possibility that this patient's illness is the result of a bioterrorist attack?

A. Isolation of Yersina pestis from the sputum and blood
B. The presence of inguinal buboes
C. A cluster of similar cases in previously healthy people
D. Respiratory failure

Answer

9. A 37-year-old man who is HIV positive is evaluated because of fever and a generalized rash. He has been in his usual state of health until 5 days ago when he suddenly developed a fever, headache, myalgias, and a painful, generalized eruption. The patient has been HIV positive for 1 year, and because he was asymptomatic, elected to postpone antiretroviral medications.

On physical examination, his temperature is 104° F (40° C), blood pressure is 140/86 mm Hg, and pulse rate is 100/min. There is a generalized vesicular-pustular eruption that is most prominent over his right shoulder, right arm, and right upper back, but a several lesions are also evident over the rest of his thorax, face, and extremities. On any one part of this body, papules, vesicles, pustules, and scabs are present. Six weeks ago his CD4 lymphocyte count was 300 /”L, and his most recent plasma viral load was 200,000 copies/mL.

Which of the following is the most likely diagnosis?

A. Disseminated herpes zoster
B. Erythema multiforme
C. Molluscum contagiosum
D. Smallpox

Answer

10. Twelve patients with fever and a generalized vesicular or pustular eruption were admitted to the hospital over the previous 2 days. After an initial investigation, it is deemed that the cases are highly suspicious for smallpox.

Which of the following smallpox vaccination strategies is most likely to have the best risk/benefit ratio?

A. National mass vaccination program
B. Ring vaccination and containment
C. Vaccination of immediate family only
D. Vaccination of the index cases

Answer

11. A 38-year-old woman is evaluated in the emergency department because of fever and a generalized rash. She was in her usual state of good health until 7 days ago. At that time, she rapidly developed a high fever, headache, backache, chills, and abdominal pain with occasional vomiting. Four days ago she developed a rash. It started as a red, flat rash, then it evolved into small papules, and now it consists entirely of vesicles. She takes no medications. She recalls having chickenpox as a child.

On physical examination, the temperature is 104° F (40° C), blood pressure is 148/90 mm Hg, and pulse is 112/minute. She appears acutely ill and is possibly confused. She has a generalized vesicular eruption on her face, extremities (including the palms and soles), thorax, and abdomen. The vesicles are well circumscribed, round, and firm to palpation.

Which of the following management options should be done next?

A. Collect fluid from the vesicles for culture
B. Have the patient wear a mask at all times
C. Institute airborne and contact precautions
D. Report the case to the Centers for Disease Control and Prevention

Answer

12. Over a 4-day period, five men, four women, and six children are admitted to Philadelphia metropolitan hospitals with fever, prostration, hypotension, and various degrees of mucosal bleeding. All patients have thrombocytopenia, leukopenia, and elevated liver and renal function tests. None of the patients have traveled outside the mid-Atlantic area in the past 3 months. A viral hemorrhagic fever is suspected.

Which one of the following epidemiological clues most strongly suggests that the outbreak is the result of a deliberate epidemic?

A. Multiple simultaneous epidemics of different diseases
B. Unusual age distribution of a common disease
C. Unusual antibiotic resistance pattern
D. Unusual geographic clustering of disease
E. Unusual route of exposure

Answer


Answer Question 1

Educational Objective: To recognize the differential diagnosis of the abrupt onset of pulmonary symptoms after exposure to a chemical mixture.

Answer: B

The patient had immediate onset of pulmonary symptoms after exposure to ammonia and bleach. This combination produces chloramine, which is a highly water-soluble irritant gas, and a common cause of both household and industrial irritant exposure. The high water solubility causes an immediate reaction with moisture in mucous membranes such as conjunctivae, upper airways, and if highly, aerosolized, as might occur with a pressure washer, lower airway irritation. Inhalational anthrax would present with a slower onset with chest pain and fever. Carbon monoxide is odorless, colorless, and non-irritating, and produces onset of headache and altered mental status. In an outdoor area it would not be expected to accumulate to a substantial degree and produce symptoms. While latex allergy may produce symptoms of anaphylaxis, burning of the eyes and throat would be unusual, and some response to inhaled bronchodilators should be expected.

References:

1. Tanen DA, Graeme KA, Raschke R, Severe lung injury after exposure to chloramine gas from household cleaners, N Engl J Med. 1999 Sep 9;341(11):848-9.
2. Olson KR, Shusterman DJ, Mixing incompatibilities and toxic exposures. Occup Med. 1993 Jul-Sep;8(3):548-60.

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Answer Question 2

Educational Objective: To evaluate and treat a patient with organophosphate poisoning.

Answer: A

The scenario of a chemical exposure with multiple casualties and a presentation with the classic muscarinic findings of hypersecretions, bradycardia, and small pupil size there leaves little doubt that this represents an organophosphate exposure. The onset of motor weakness signals the nicotinic action of the poisoning. Immediate action with airway management and administering pralidoxime to reconstitute the blocked enzyme, acetyl cholinesterase, is urgently required. Atropine is also critical to dry up the secretions and block the muscarinic effects. Bronchospasm, a significant component of organophosphate poisoning, may be treated with ipratropium. However, in the situation described, the most critical step is reversing the effects of motor paralysis before the agent "ages". Subcutaneous scopolamine, another anticholinergic agent, would be too slow a route and too unpredictable a dose to make any difference in this scenario. Cyanide is not likely to be the agent responsible here. Cyanides would produce gasping and sudden cardiopulmonary collapse, but the prodrome would not include the hypersecretory phase and bradycardia would only occur as a preterminal event. While an acute inferior myocardial infarction could present with diaphoresis and bradycardia, the absence of chest pain, and the occurrence with a chemical exposure with simultaneous multiple victims make this much less likely.

Reference:

1. Holstege CP, Kirk M, Sidell FR, Chemical Warfare: Nerve Agent Poisoning, Crit Care Clinics, 1997, 13:923-942.

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Answer Question 3

Educational Objective: Recognize the clinical appearance of sporotrichosis and be able to distinguish from other infections, particularly those that might be associated with a bioterrorist attack.

Answer: B

Sporotrichosis is an infection caused by Sporothrix schenckii, a fungus that occurs naturally in both temperate and tropical locations. Of the two clinical syndromes of sporotrichosis, the subcutaneous and the systemic, the subcutaneous variety is the most common form. The organism is introduced into the skin through a local injury, such as a thorn prick. The lymphatic form of subcutaneous sporotrichosis is the most common and usually develops on exposed skin sites such as the hands or feet. The infection begins as a nodule that may break down to form a small ulcer. The draining lymphatics become inflamed and swollen and a chain of secondary nodules develops along the course of the lymphatics. These may also break down and ulcerate. The nodules are mildly painful, and systemic symptoms are mild or absent. Sporotrichosis is associated with gardening and outdoor occupations.

Anthrax is caused by Bacillus anthracis, a sporulating, gram-negative bacillus. Clinical characteristics highly suggestive of cutaneous anthrax include: (1) painless ulcer covered with black eschar; (2) surrounding edema out of proportion to the ulcer; and (3) paucity of neutrophils in vesicular fluid. Symptoms include low-grade fever and malaise. Regional lymphadenopathy is present early on. The presence of a painful nodule and absence of an eschar and surrounding edema make anthrax unlikely.

Leishmaniasis is an infection caused by the protozoan parasite belonging to the genus Leishmania. Three forms are recognized, bubonic, systemic, and pneumonic. The natural reservoirs are rodents and domesticated dogs, and the vector is the sandfly, a small mosquito-like insect. Ninety percent of all cases occur in Saudi Arabia, Iran, Afghanistan, Brazil, and Peru. The disease begins as a small, red, painless papule, usually within 2 to 4 weeks of the sandfly bite. The papule enlarges to approximately 2 cm over the next 2 to 4 weeks and becomes dusky red to violaceous in color. The lesion becomes crusted over, and if the crust is removed, a shallow ulcer can be found with a raised, indurated border. Cutaneous leishmaniasis may be associated with small satellite lesions and nodules along the course of the draining lymphatics. The absence of travel to an endemic area makes leishmaniasis unlikely.

Plague is caused by Yersina pestis, a gram-negative bacillus endemic in Arizona, Colorado, California, and New Mexico. Transmission to humans occurs in one of five ways: bite or bites from an infected flea; human-to-human transmission of pneumonic plague; handling of infected animal carcasses; cat bites or scratches; or, aerosolization of bacteria. The initial cutaneous manifestation of bubonic plague appears 2 to 8 days following the fleabite, and can easily be missed. Developing at the site of the fleabite, the primary lesion consists of a small papule, or vesicopustule. This stage is soon followed by the abrupt onset of fever, chills, headache, weakness, and tender, proximal lymphadenopathy. The involved nodes become enlarged, matted, and associated with extensive overlying erythema and edema (buboes). In the setting of bacteremia, petechiae and ecchymosis develop, and eschars may be seen. Eschars and ecthyma gangrenosum-like lesions can also develop at the site of the fleabite in the absence of bacteremia. Lack of travel to an endemic area and absence of significant systemic systems makes plague unlikely in this patient.

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Answer Question 4

Educational Objective: Be able to recognize cutaneous anthrax and distinguish it from other causes of ulceroglandular fever.

Answer: A

Cutaneous anthrax is caused by Bacillus anthracis. It may present with or without fever and lymphadenopathy. When these conditions are present, cutaneous anthrax must be differentiated from other causes of ulceroglandular fever. The distinguishing characteristics of cutaneous anthrax include a painless ulcer that is surrounded by a non-pitting, gelatinous edema that is out of proportion to the size of the ulcer. While an eschar is characteristic of anthrax, it is not unique and is present in other causes of ulceroglandular fever syndromes.

Cat-scratch disease is a common, benign condition, most commonly caused by Bartonella henselae. It is usually transmitted by a bite or scratch of a kitten or a cat with fleas. The condition characteristically affects children and younger adults under the age of 21 years. In the typical case, within 2 to 3 days of inoculation, a papule will develop, progresses to a vesicle, which is followed by proximal lymphadenopathy in about two weeks. Rarely, the primary lesion at the site of inoculation is pustular or nodular. Cutaneous anthrax is rarely, if ever, pustular. The presence of a painless ulcer covered by an eschar surrounded by edema makes cat scratch disease an unlikely diagnosis.

Tularemia is caused by Francisella tularensis, a gram-negative coccobacillus. Six clinical syndromes are recognized: ulceroglandular, glandular, typhoidal, pneumonic, oropharyngeal, and oculoglandular. Sixty percent to 80% of the cases are ulceroglandular, and are the result of direct contact with infected animals, an animal bite, or an insect vector. After an incubation period of 2 to 10 days, there is an abrupt onset of fever, chills, headache, and myalgias. The primary lesion develops at the site of inoculation, usually the hand, and is associated with regional lymphadenopathy, and occasionally, nodular lymphangitis. The primary lesion begins as a single, red, painful papule, that develops a central ulcer with raised margins, often covered by a black eschar. Systemic toxicity can be marked. The absence of multiple, painful ulcerated nodules makes tularemia is an unlikely diagnosis.

Herpes simplex viruses, type 1 and type 2 cause a variety of primary and recurrent mucocutaneous infections. In the normal host, herpes simplex most commonly presents as grouped painful, sometimes pruritic vesicles on a red base. In the immunocompromised patient, herpetic infections may be associated with progressive mucocutaneous ulcerations of the face, mouth, or anogenital regions. Lesions may coalesce, forming large, superficial ulcers that last for weeks or months. The absence of painful, superficial vesicles or ulcers makes herpes unlikely an unlikely cause of this patient's ulcer.

Acute lymphangitis is an inflammatory process that involves the superficial lymphatic system. It is most often the result of group A streptococci but can result from Staphylococcus aureus or Pasturella. multocida infections. The portal of entry is usually a wound on the extremity, infected blister, or paronychia. Pain along the lymphatics and regional draining lymph nodes is common as are systemic symptoms. The diagnosis is suggested by the appearance of red, linear streaks extending from the primary lesion toward the regional lymph nodes, which are enlarged and tender. Rarely, the skin over the primary lesion may break down forming an ulcer. The absence of painful red streaking proximally from the ulcer makes acute lymphangitis an unlikely cause of this patient's ulcer.

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Answer Question 5

Answer: A

Educational objective: Distinguish chickenpox from smallpox and other acute, vesicular eruptions.

The children have a classic varicella eruption. Chickenpox is contagious before the development of the rash, and multiple outbreaks 10 to 21 days after contact with a common source is quite typical. In children, the prodrome before the eruption is quite mild, and significant illness is distinctly unusual. The rash develops in a centripetal fashion, with the greatest concentration of lesions on the trunk and fewest on the distal extremities. The lesions develop in crops such that on any one part of the body, vesicles, pustules and scabs can be identified. The classic lesion is a superficial, thin-walled vesicle on an erythematous base, appearing as a "dew-drop on a rose petal."

Smallpox is associated with a severe prodrome consisting of body temperature > 101° F (> 38.3° C), headache, backache, chills, myalgias, occasionally severe abdominal pain and vomiting, and prostration. The rash spreads centrifugally, with the greatest concentration of lesions on the face and distal extremities, including the soles and palms. In contrast to chickenpox, smallpox lesions are located deeper in the skin, are round, well circumscribed, and firm to palpation. On any one part of the body, the lesions tend to be all in the same stage of development; all are papules, vesicles, pustules, or scabs. In some patients, the rash can become confluent, particularly on the face and distal extremities. In contrast to chickenpox, the rash evolves slowly over days from papules, to vesicles, pustules, and scabs.

Hand-foot-mouth disease is a common disease of childhood that presents with fever and small, gray oval vesicles with a pink halo on the oral mucosa, tongue, hands and feet. Affected children may have fever and pharyngitis.

Herpes zoster is an acute, unilateral vesicular eruption that follows one or two cutaneous dermatomes. Like chickenpox, the rash of herpes zoster is characterized by the simultaneous occurrences of vesicles, pustules, and scabs. While herpes zoster can disseminate in some patients, this would be unusual in children with intact immune systems.

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Answer Question 6

Answer: A

Educational Objective: Recognize the clinical features of botulism and distinguish it from other causes of flaccid paralysis.

Botulism is an acute, symmetric descending flaccid paralysis caused by the botulinum toxin that always begins in the bulbar musculature. Botulism may be suspected by its classic triad: (1) symmetric, descending flaccid paralysis with prominent bulbar palsies, (2) afebrile patient, and (3) clear sensorium. The bulbar palsies highly suggestive of botulism can be remembered as the "4 Ds": diplopia, dysarthria, dysphonia, and dysphagia. The presence of a compatible syndrome, particularly when presenting as part of a cluster of cases, makes botulism the most likely diagnosis responsible for this patient's symptoms. While clustering of cases should raise the possibility of a bioterrorist attack, natural epidemics can occur when persons have a common dietary exposure. Since the most likely method of deliberate dissemination of botulinum toxin is aerosolization of toxin, suspicion of a bioterrorist attack is increased when a large number of cases share a common temporal and geographic exposure but lack a common food exposure.

The polyradiculopathies, including Guillain-BarreŽ syndrome, are frequently mistaken for botulism. Guillain-BarreŽ presents as an ascending flaccid paralysis following a gastrointestinal or respiratory infection. Loss of deep tendon reflexes occurs early in the course of the disease, and generally bulbar manifestations are a later complication.

The cardinal features of myasthenia gravis are increasing muscle weakness and fatigue with exertion that improves with rest. Weakness often begins first in the eyes, but may begin in the bulbar muscles or muscles of the trunk and limbs. As with botulism, weakness of the eye muscles can lead to ptosis and diplopia, but unlike botulism, myasthenia gravis always spares the pupils, helping differentiate the two disorders.

Poliomyelitis is an acute febrile illness that is associated with flaccid paralysis of one or more limbs. Paralytic disease due to the wild virus no longer occurs in the Western Hemisphere but is a rare complication of the oral vaccine. Poliomyelitis can be differentiated from botulism by its association with a fever and asymmetric paralysis.

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Answer Question 7

Answer: C

Learning Objective: Recognize the appropriate public health reporting responsibility when a deliberate biological attack is suspected.

If a physician suspects bioterrorism is responsible for a patient's illness or for a cluster of illnesses, immediate contact should be made with a public health official of the local health department and with the hospital epidemiologist or infection control specialist. Contact should be made at the time when a sentinel disease is suspected, prior to its confirmation. In addition, the hospital laboratory should be informed of the clinical suspicions in order to facilitate the identification of the agent and to prepare the laboratory to receive potentially very dangerous specimens. In some cases, the specimens may have to be transmitted to a laboratory that has special handling facilities for these agents.

The investigation and infection control of these agents is the responsibility of the local public health organization and the hospital infection control committee, not the Centers for Disease Control and Prevention. It is the responsibility of the local public health organization to inform the CDC.

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Answer Question 8

Answer: C

Educational objective: Recognize the epidemiologic clues that suggest the possibility of a deliberate epidemic.

While no single epidemiologic clue is pathognomonic for a bioterrorist event, the presence of rapidly progressive gram-negative bronchopneumonia in a cluster of previously healthy persons should raise the index of suspicion. Other clues include unusual temporal or geographic clustering of illness, unusual age distribution for common illnesses, a large epidemic with greater case loads than expected, more severe disease than expected, unusual route of exposure, a disease that is outside its normal transmission season or impossible to transmit in the absence of its normal vector, multiple simultaneous epidemics of different diseases, and unusual strains of organisms or antimicrobial resistance patterns.

The isolation of Yersina pestis, the bacterium responsible for plague, does not in itself suggest a bioterrorist event, since plague is endemic in the southwest United States, particularly in Arizona, New Mexico, Colorado, and California. The presence of painful, swollen and matted lymph nodes (buboes) helps rule out a deliberate infection. The bubonic form of plague is the most common presentation of naturally acquired infection, and pinpoints the source of the infection as bites by infected fleas or contact with infected animals. The source of a deliberate infection would most likely be aerosolized bacteria, and the clinical presentation would be pneumonic plague. While this patient may have pneumonic plague, it can, rarely, be acquired naturally, and the occurrence of a single case does not strongly support a bioterrorist attack.

Respiratory failure due to a rapidly progressive, gram-negative pneumonia in a single individual does not suggest a bioterrorist attack. Multiple cases of respiratory failure in previously health persons do suggest the possibility of a deliberate attack. In this situation, the differential diagnosis includes pneumonic plague, inhalational anthrax, and inhalational tularemia.

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Answer Question 9

Answer: A

Learning Objective: Distinguish the clinical presentation of disseminated herpes zoster from smallpox and other acute, generalized vesicular-pustular eruptions.

Considering the immune status of the patient, the most likely diagnosis is disseminated herpes zoster infection. This is supported by the nature of the eruption, which includes the simultaneous occurrence of vesicles, pustules, and scabs on any one part of his body. The density of the lesions over his right shoulder, arm, and upper back suggests the possibility of a localized dermatomal eruption that later generalized, which is also consistent with disseminated herpes zoster.

Like herpes zoster, smallpox is an acute, febrile, vesicular-pustular eruption. The smallpox prodrome consists of temperature > 101 F (> 38.3° C), headache, backache, myalgias, backache, severe abdominal pain and vomiting, and prostration. The prodrome of smallpox and disseminated herpes zoster may be difficult to distinguish from each other; however, several other clinical findings are helpful. Although a generalized eruption, smallpox is most heavily concentrated on the face and distal extremities, including the palms and soles. On any one part of the body, only one type of lesion predominates; the lesions are all papules, vesicles, pustules, or scabs. Finally, in smallpox the evolution of the lesions from papules to vesicles, pustules, and scabs occurs more slowly, over several days, as compared to 1 to 2 days in herpes zoster or chickenpox.

Molluscum contagiosum is a common, benign eruption that tends to be localized to one part of the body, but can become generalized in certain individuals, including those with immune deficiencies. Molluscum contagiosum is not associated with fever or other prodromal symptoms, and lesions are umbilicated flesh-colored or pink papules, not vesicles, pustules, or scabs.

Erythema multiforme often appears as erythematous macules or edematous papules with an outer edematous ring and a violaceous or dark center. The lesions also may appear urticarial or bullous. Mucosal lesions are present in up to 70% of affected patients. Common causes of erythema multiforme include drug reactions and recurrent herpes simplex infections. A generalized eruption consisting of vesicles, pustules, and scabs would not be consistent with erythema multiforme.

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Answer Question 10

Answer: B

Educational objective: Understand the role of vaccination following a smallpox outbreak and the strategy associated with the best risk/benefit ratio.

If performed early in the incubation period, vaccination can markedly reduce or eliminate the clinical manifestations of smallpox. The strategy that was successful in eliminating naturally occurring smallpox was the ring vaccination and containment strategy. This strategy involves the identification and vaccination of persons with face-to-face contact or household contact with an infected patient. In addition, an investigation of all persons and places in contact with infected patients starting 3 weeks before the onset of the patient's illness is done to identify other persons to be included in the ring vaccination and containment strategy.

Mass vaccinations raise the risk of increased numbers of vaccine related complications. Children under the age of 5 years have the highest rates of vaccine-related complications and they tend to be the most severe. A nationwide study showed that the case fatality rate was 1 per million primary vaccinations. If a nation-wide vaccination program were implemented, nearly 280 vaccine-related deaths could be anticipated. The complication rate is likely to be even higher in immunosuppressed patients.

While the family members of infected patients should be vaccinated, limiting the vaccination program to family members only will not contain the epidemic. Vaccination of patients already symptomatic with smallpox will not alter their clinical course nor provide protection to others who come in contact with them.

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Answer Question 11

Answer: C

Educational objective: Recognize the importance of isolating a patient that is at high risk for smallpox.

Based upon the history and physical examination, this patient is at high risk for smallpox. She developed an acute, febrile prodrome followed by the development of a generalized rash that evolved over several days through macular, papular, then vesicular stages. At any one time, the lesions were all in the same stage of development. She also confirms a history of a chickenpox, which is therefore an unlikely cause of the current illness.

The first priority is to contain the infection by the implementation of airborne and contact precautions. The patient should be placed in a private, negative-airflow room and the door should be kept closed at all times, other than to let staff enter and exit. Staff and visitors alike should wear N95 (or higher quality) respirators, gloves, and gowns. At the time the patient is transported, she should wear a surgical mask and be gowned or wrapped in a sheet so that the rash is fully covered. While the patient is isolated in the negative-airflow room, it is not necessary for her to wear a mask or have her rash covered.

The possibility of a smallpox case must be immediately reported to the local or state health department. This should be done when a case is suspicious for smallpox and not be delayed to confirm the diagnosis. Hospital infection control should be informed of the suspicious case as well. It is the responsibility of the state or local health department to notify the Centers for Disease Control and Prevention about suspicious cases.

Specimen collection for laboratory diagnostic studies should be performed only after the patient has been isolated and the state and federal response teams have been consulted.

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Answer Question 12

Answer: D

Learning Objective: Recognize the epidemiological clues suggestive of a bioterrorist attack

Viral hemorrhagic fevers have a worldwide distribution, but multiple occurrences of one of these diseases in mid-Atlantic American city would be distinctly unusual without a travel history to an endemic site. Therefore, the unusual geographic clustering of a disease is the clue most highly suggestive of a deliberate epidemic in this situation.

Each of the remaining options can be important clues to a bioterrorist attack but are not pertinent to the presented situation. For example, an epidemic of chickenpox in adult patients would be a distinctly unusual presentation of a common disease outside of its normal age distribution, since almost 90% of adults over the age of 21 years have immunity. The chickenpox may actually represent misdiagnosed cases of smallpox, and such an outbreak would most certainly be the result of a bioterrorist attack.

Unusual antibiotic resistance patterns suggest the possibility that the target organism has been genetically altered to create a more potent biological threat. While suggestive of a deliberate epidemic, this is not a likely finding for any of the viral particles responsible for viral hemorrhagic fever syndromes.

An unusual route of exposure can suggest a bioterrorist attack. For example, the occurrence of numerous cases of pneumonic plague would be unusual, since most naturally occurring cases are bubonic, secondary to infected fleabites, animal bites or scratches, or handling contaminated carcasses. The occurrence of multiple cases of pneumonic plague suggests the deliberate aerolsolization of bacteria. However, in this case, the route of infection has not been established, so this clue is not pertinent.

Finally, the occurrence of multiple epidemics of different diseases is a highly likely scenario for a coordinated bioterrorist attack. For example, simultaneous outbreaks of plague, tularemia, and anthrax in the same geographic area would be almost certainly indicative of a deliberate epidemic. However, there is nothing in the current situation to suggest the presentation of more than one disease, since the presenting signs and symptoms are so similar.

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