Block 11 - Week 12 - Viral Hemorrhagic Fevers
Questions and Answers
- 1.
A 38-year-old male UN peacekeeper returning from Liberia, western Africa, presents with fever, malaise, asthenia, cough, sore throat, abdominal pain, diarrhea, nausea, and vomiting. Later in the course of the disease, the patients presents with mucosal bleeding, conjunctival injection, face edema, rales, and hypotension. The patient is treated with ribavirin administered intravenously. Pre-immune serum from the patient is negative for hemorrhagic fever viruses, but serum obtained from the patient 15 days after resolution of the illness is positive for an enveloped, segmented (-) ssRNA virus. What is the reservoir host of the virus responsible for this patient’s disease?
- A.
Humans
- B.
Bats
- C.
Ticks
- D.
Rats
- E.
Mosquitoes
Correct Answer
D. RatsExplanation
The correct answer is Rats. Rats are the reservoir host for the virus responsible for this patient's disease. This is indicated by the symptoms and the positive serum test for an enveloped, segmented (-) ssRNA virus. Rats are known to carry and transmit various diseases, including some viral infections.Rate this question:
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- 2.
A patient returning from Uganda presents with abrupt onset of fever, weakness, diarrhea, nausea and vomiting, and a maculopapular rash. Pre-immune serum from the patient is negative for hemorrhagic fever viruses, but serum obtained from the patient 15 days after resolution of the illness is positive for an enveloped, (-) ssRNA filamentous virus. What is the reservoir host of the virus responsible for this patient’s disease?
- A.
Rats
- B.
Humans
- C.
Bats
- D.
Ticks
- E.
Mosquitoes
Correct Answer
C. BatsExplanation
The correct answer is bats. Bats are known to be reservoir hosts for many viruses, including those causing diseases such as Ebola and Marburg. In this case, the patient's serum tested positive for an enveloped, (-) ssRNA filamentous virus, which is characteristic of many viruses carried by bats. Bats can transmit these viruses to humans through direct contact or through intermediate hosts, such as mosquitoes or ticks. This is supported by the patient's symptoms, which are consistent with a viral infection, and the fact that the patient had recently returned from Uganda, where bats are known to carry various viruses.Rate this question:
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- 3.
Which of the following viruses, known to be associated with viral hemorrhagic fevers, can induce an immune response, which may result in a more severe disease if the patient is subsequently infected with a heterologous strain of the same virus?
- A.
Yellow fever virus
- B.
Ebola virus
- C.
Dengue virus
- D.
Marburg virus
Correct Answer
C. Dengue virusExplanation
Dengue virus is known to induce an immune response that can lead to a more severe disease if the patient is subsequently infected with a different strain of the same virus. This phenomenon is called antibody-dependent enhancement (ADE) and occurs when the antibodies produced during the first infection bind to the new strain of the virus, facilitating its entry into immune cells and increasing viral replication. This can result in a more severe form of dengue fever, known as dengue hemorrhagic fever or dengue shock syndrome.Rate this question:
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- 4.
Your patient is a Native American living on the border between Arizona and Utah. He presented with alternating fever and chills, myalgia, nausea with vomiting and a marked petechial rash over his body. This is the third case you have seen recently from patients from the same Native American reservation. There is no apparent reason for these outbreaks, except that the weather has been even dryer than usual in this region and many mice and other rodents have been seen near human habitation looking for food. Which of the following viruses might you suspect is causing your patient’s condition?
- A.
Crimea-Congo Hemorrhagic virus
- B.
Hantavirus
- C.
Rift Valley virus
- D.
Dengue virus
Correct Answer
B. HantavirusExplanation
The correct answer is Hantavirus. Hantavirus is transmitted to humans through contact with infected rodents, particularly their urine, droppings, or saliva. The symptoms described in the patient, such as fever, chills, myalgia, nausea, vomiting, and petechial rash, are consistent with Hantavirus infection. The presence of mice and other rodents near human habitation due to the dry weather increases the likelihood of exposure to the virus. Additionally, the fact that there have been other cases from the same Native American reservation suggests a localized outbreak of Hantavirus.Rate this question:
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- 5.
On a Caribbean island, about 20 patients last year were hospitalized with fever, myalgia, and petechial skin rashes. Two of them died with shock. The outbreak was caused by dengue virus of serotype 2. Ten years earlier there had been an island outbreak of dengue caused by serotype 1. Why was last year’s disease so severe?
- A.
Low concentrations of cross-reacting antibodies from exposure to serotype 1 were not sufficient to neutralize virus of serotype 2
- B.
Antibodies against serotype 1 were present but did not cross-react with virus of serotype 2
- C.
Antibodies against serotype 1 cross-reacted with virus of serotype 2 to opsonize virus for greater uptake by macrophages
- D.
Antibodies against serotype 1 cross-reacted with virus of serotype 2 to block its phagocytosis by macrophages
Correct Answer
C. Antibodies against serotype 1 cross-reacted with virus of serotype 2 to opsonize virus for greater uptake by macrophagesExplanation
Last year's disease was so severe because the antibodies against serotype 1 cross-reacted with the virus of serotype 2, causing opsonization. Opsonization is a process where antibodies bind to pathogens, marking them for destruction by phagocytes like macrophages. In this case, the cross-reacting antibodies from exposure to serotype 1 opsonized the virus of serotype 2, leading to greater uptake by macrophages. This increased uptake of the virus by macrophages could have resulted in a more severe disease outcome.Rate this question:
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- 6.
Yellow fever virus differs from dengue virus in which way?
- A.
It is a flavivirus whereas dengue is a filovirus
- B.
It occurs in Asia whereas dengue is limited to South America and Africa
- C.
It is a naked RNA virus whereas dengue is an enveloped virus
- D.
It invades the liver whereas dengue is mainly in macrophages and blood
Correct Answer
D. It invades the liver whereas dengue is mainly in macrophages and bloodExplanation
Yellow fever virus differs from dengue virus in that it invades the liver, whereas dengue virus is mainly found in macrophages and blood.Rate this question:
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- 7.
A 5-year-old girl in the Caribbean developed fever, fatigue, and headache that persisted for 5 days. As these symptoms were subsiding she noted a red rash on her trunk. She was taken to the family doctor, who described the rash as macular and blanching but some of the spots were petechial and non-blanching. The blood pressure fell to 80/55. She was hospitalized and given intravenous saline. After 3 days the blood pressure rose to 106/74, the rash faded, and she was discharged in improved condition. What are features of this disease?
- A.
It is caused by a Flavivirus and spread by Anopheles mosquitoes
- B.
Hemorrhage and shock can result from re-infection by a different serotype of the same virus
- C.
It is caused by Hantavirus and spread by Aedes mosquitoes
- D.
Antibodies against the virus provide immunity that is cross-protective against multiple serotypes of the same virus
Correct Answer
B. Hemorrhage and shock can result from re-infection by a different serotype of the same virusExplanation
The features of this disease include hemorrhage and shock that can occur as a result of re-infection by a different serotype of the same virus. This is supported by the fact that the patient experienced a drop in blood pressure and had petechial and non-blanching spots on her trunk, indicating bleeding. The mention of a rash and fever also suggests a viral infection. The other options are incorrect as they do not align with the symptoms and presentation described in the scenario.Rate this question:
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Current Version
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Mar 21, 2023Quiz Edited by
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Jul 16, 2012Quiz Created by
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