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28 Cards in this Set

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A previously healthy 32 year old male is admitted with a tentative diagnosis of viral encephalitis. There is no history of exposure to mosquitoes in the last couple of weeks and there is no known outbreak of viral encephalitis in the community. A needle biopsy of the temporal lobe of the brain shows cells with intranuclear inclusion bodies. What is the most likely etiological agent for this patient's encephalitis
A herpes simplex virus. The finding of cells with intranuclear inclusion bodies is highly suggestive of the involvement of DNA virus
What are the five most frequent causes of viral encephalitis
Herpes simplex virus
VZ virus
Echovirus
Flavivirus
Paramyxovirus
18 month old baby girl presented to the ER with fever and a diffuse rash. 40C, ht 180. Rash, more pronounced in the trunk, with both macular and vesicular lesions. Four vesicular lesions could be seen in the soft palate. CXR clear. WBC 9,000 with normal differential. Diagnosis?
Chickenpox. The centripetal nature of the rash and the simultaneous presence of lesions in different stages of evolution are typical of chickenpox
Scarlet fever is associated with what type of rash
Erythematous rash
Measles and Roseola infantum are associated with what type of rash
Maculopapular (morbiliform) rashes
A 56-year-old woman under treatment for inoperable breast cancer develops a rash. Cytological examination of scrapings from the base of one of the vesicles reveals cells with intranuclear inclusions. The virus responsible for these lesions most likely has what characteristics
DNA virus, Enveloped, Icosahedral. The clinical history and presentation are characteristic of Zoster (shingles), caused by Varicella-Zoster virus. The VZV is an enveloped, icosahedral virus with DNA genome
A child presents with the lesions shown in the figure, similar lesions in the soles of the feet, and multiple vesicular eruptions on the hard palate. Which other of the listed diseases is most likely to be caused by the same strain of the involved infectious agent?
A. Cervical carcinoma
B. Genital warts
C. Infantile diarrhea
D. Myocarditis
E. Pleurodynia
C. Infantile diarrhea. The clinical picture is that of hand-foot-and-mouth disease, caused by Coxsackie A viruses of many different serotypes. Of the diseases listed as possibly associated with the same virus, infantile diarrhea is most commonly associated with Coxsackie A viruses
Coxsackie B viruses usually cause what complications
Myocarditis and pleurodynia
66 year old woman receiving chemotherapy for inoperable breast cancer develops a painful vesicular hemorrhagic rash in her right anterior chest. How would you confirm the diagnosis
Perform a direct immunofluorescence study on a smear of the base of a vesicle using enzyme-labeled VZV antibodies. The clinical presentation is suggestive of Zoster (shingles). To confirm the diagnosis it is necessary to obtain unquestionable evidence for the presence of VZV in the lesions, and that can be done by direct immunofluorescence
Guarnieri bodies are associated with what infections
Poxvirus infections
A 66-yr. old woman receiving chemotherapy for inoperable breast cancer develops a painful vesicular hemorrhagic rash in her right anterior chest. Cytological examination of scrapings from the base of one of the vesicles reveals the cells shown in the picture. In addition to the illustrated cytopathic effect, the virus responsible for these lesions may cause what
Intranuclear inclusion bodies. VZV, like all members of the human Herpes group, replicates in the nucleus, and therefore replication can be associated with intranuclear inclusion bodies. The other illustrated cytopathic effect seen in cells infected with VZV is the formation of multinucleated giant cells.
What virus may cause B cell immortalization
Epstein-Barr virus
The expression of T antigens on the membrane of infected cells is characteristic of what viruses
Polyoma viruses
Intracytoplasmic inclusion bodies can be seen in cells infected with what
Pox viruses or several RNA viruses, all of them replicating in the cytoplasm
A 66-yr. old woman receiving chemotherapy for inoperable breast cancer develops a painful vesicular hemorrhagic rash in her right anterior chest. What is the source of the etiological agent of this patient's disease
Reactivation of a latent infection. The primary infection with VZV is usually acquired in childhood and presents as chickenpox. The virus then may remain latent in the dorsal ganglia for long periods of time, and may reactivate under favorable circumstances, causing shingles. Chickenpox may be acquired by direct contact with an infected patient, but is most frequently transmitted by inhalation of contaminated secretion droplets
Which of the following viruses reaches its target organ by hematogenous dissemination?
A. Herpes simplex virus
B. Papilloma virus
C. Rhinovirus
D. Rotavirus
E. Rubella virus
The correct answer is E. With the exception of Herpes simplex and VZV viruses that reach the skin through retrograde diffusion through nerve roots, all rash-causing viruses reach the skin through viremia. Of those viruses listed as possible choices, only Herpes simplex and Rubella virus cause skin rashes. Papilloma viruses cause skin and mucosal warts, rhinoviruses are agents of the common cold, and rotaviruses cause infantile diarrhea.
Which of the following diseases is usually spread by respiratory secretions?
A. ARDS associated with the Sin Nombre virus
B. Dengue
C. Measles
D. Viral encephalitis
E. Yellow fever
The correct answer is C. Measles is transmitted through inhalation of aerosolized infected secretions exhaled when an infected patient coughs. Dengue, Viral encephalitis, and Yellow fever are transmitted by mosquito bites. Sin Nombre virus is transmitted by contact with infected rodent excreta
Which of the following diseases with cutaneous expression is caused by a virus that does NOT belong to the human herpes virus family?
A. Chicken pox
B. Infectious mononucleosis
C. Kaposi's sarcoma
D. Molluscum contagiosum
E. Roseola infantum
The correct answer is D. Molluscum contagiosum is caused by a poxvirus, while all the other conditions listed are caused by viruses of the human herpes group (A-VZV, B-Epstein-Barr virus, C-HHV-8, and E- HHV-6 and7).
A 32-year old male is admitted with a tentative diagnosis of viral encephalitis. There is no history of exposure to mosquitoes in the last couple of weeks and there is no known outbreak of viral encephalitis in the community. A needle biopsy of the frontal lobe of the brain is inconclusive. An MRI of the brain is compatible with viral encephalitis. What is the most important intervention in this patient
Start treatment with acyclovir immediately. Of all the common agents of viral encephalitis, HSV-1 and 2 are the only ones that can be effectively treated with anti-viral agents (acyclovir and related compounds)
A sexually active 22-year-old male presents to the STD clinic with the lesions shown in the picture. A scrapping of the base of one of the vesicles shows multinucleated giant cells. He explains that he had a similar eruption in the same area two months earlier. The recurrent nature of this patient's lesions is a consequence of what
Repeated reactivation of a latent infection in a sensory ganglia. HSV and VZV viruses tend to remain latent in sensory ganglia and cause vesicular rashes when reactivated.
A sexually active 22-year-old male presents to the STD clinic with the lesions shown in the picture. A scrapping of the base of one of the vesicles shows multinucleated giant cells. He explains that he had a similar eruption in the same area two months earlier. What is the best preventive measure to avoid transmission of this disease to this patient's sexual partners
Use of barrier contraceptives. When lesions are obvious, sexual intercourse should be avoided altogether. However, transmission is possible without obvious lesions, and the routine use of barrier contraceptives should be strongly recommended to patients known to have herpes genitalis, even when the lesions are not detectable.
A child presents with multiple vesicular eruptions on the mucous membranes of the mouth which resolve spontaneously within three weeks. However, during the next twelve months, the child suffers several recurrent infections, characterized by blisters in the epidermo-mucosal junction of the peri-oral region. In all cases there is complete spontaneous recovery followed by symptom-free intervals. What type of drug is most likely to be useful to alleviate this child's symptoms?
An inhibitor of viral DNA synthesis. This is a typical description of recurrent herpes simplex. The drugs of choice for herpes simplex (acyclovir and related compounds) block viral DNA synthesis. Protein synthesis inhibition is not an effective strategy for anti-viral therapy because viral proteins are synthesized by the host ribosomes, and the drugs would inhibit both viral and host protein synthesis, therefore with high degree of toxicity.
A child presents with multiple vesicular eruptions on the mucous membranes of the mouth which resolve spontaneously within three weeks. However, during the next twelve months, the child suffers several recurrent infections, characterized by blisters in the epidermo-mucosal junction of the peri-oral region. In all cases there is complete spontaneous recovery followed by symptom-free intervals. The low toxicity of the anti-viral agents used to treat this infection is a consequence of what
The fact that these drugs penetrate non-infected cells very poorly. Acyclovir and related compounds are administered in an inactive form that needs to be phosphorylated in order to block DNA synthesis. The initial phosphorylation requires a viral thymidine kinase, and therefore, the drug is only activated in infected cells and the toxicity is minimal.
A 5-yr. old girl presents with fever (103ºF) and a rash that started in the trunk and has spread to the face. Physical examination shows maculopapular, vesicular, pustular, and crusted lesions in several areas of the body. This child has most likely an infection caused by:
Varicella-Zoster virus. The rash described in this patient is typical of chickenpox - predominance in the trunk and lesions in various stages of development (crops). Chickenpox is caused by VZV
A 5-yr. old girl presents with fever (103ºF) and a rash that started in the trunk and has spread to the face. Physical examination shows maculopapular, vesicular, pustular, and crusted lesions in several areas of the body. This girl has a 2-yr-old sister that became ill with a similar disease four weeks after she was sick and an older brother that has remained healthy. The older brother attends public school, the older sister attends pre-school at her brother's school, and the younger sister stays at a private kinder garden. What would be the most likely source of infection for the young sister?
Other children attending the kinder garden. The incubation period for chickenpox is usually of about two weeks, maximum three. The possibility that the virus was transmitted to the brother, who remained asymptomatic, and from him to the younger sister, cannot be completely ruled out but is highly unlikely
The mother of an 18-month old girl seeks medical attention because her daughter is febrile, restless, and refuses food. Physical examination is unremarkable except for the fact that several small vesicular lesions, some ulcerated, are seen in the tonsils and posterior pharynx. The agent most likely to cause this disease has what characteristics
It is a positive RNA enterovirus. The clinical diagnosis in this case would be herpangina, caused by one of the Coxsackie A viruses, which are (+)RNA enteroviruses of the picornavirus group.
The mother of an 18-month old girl seeks medical attention because her daughter is febrile, restless, and refuses food. Physical examination is unremarkable except for the fact that several small vesicular lesions, some ulcerated, are seen in the tonsils and posterior pharynx. What is the best treatment for this child's disease
Supportive. There is no known antiviral agent affective against Coxsackie viruses, and herpangina follows a benign course.
Which of the following viruses reaches its target organ by hematogenous dissemination?
A. Coxsackie B viruses
B. Herpes simplex virus
C. Norwalk virus
D. Rabies virus
E. Rhinovirus
The correct answer is A. Coxsackie B viruses are enteroviruses that cause disease in various target organs (e.g., heart) that are reached by hematogenous dissemination. Norwalk virus is acquired by ingestion and causes disease in the GI tract. Rabies virus and HSV virus reach their target organs through nervous tissue. Rhinoviruses are acquired by inhalation and cause infection of the upper respiratory tract.