Questions

New World arenaviruses — Questions

Study questions about New World arenaviruses — exam-style, clinical-scenario and FAQ.

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16 questions: 16 MCQ, 0 written.

The pathogenic New World (clade B) arenaviruses enter cells through transferrin receptor 1, whereas the Old World viruses and clade C use alpha-dystroglycan.

Sialic acid, CD4 and angiotensin-converting enzyme 2 are receptors for other viruses, not the arenaviruses.

About a tenth of patients given immune plasma for Argentine haemorrhagic fever develop a late, self-limiting neurological syndrome with fever and cerebellar signs, some weeks after apparent recovery.

The other complications are not features of this treatment.

Acute diagnosis rests on reverse transcription polymerase chain reaction and antigen detection, performed under maximum containment, because the antibody response develops too slowly to help early.

Serology is for later or for surveillance, and dengue is an important early differential.

The South American haemorrhagic fevers carry a more prominent neurological picture than Lassa, with thrombocytopenia and leucopenia but a normal or only mildly raised aspartate aminotransferase.

Marked hepatitis, an absence of blood-count changes, a chickenpox-like rash and isolated renal failure are not their pattern.

Guanarito virus, the cause of Venezuelan haemorrhagic fever, is carried by the cane mouse Zygodontomys brevicauda in the states of Portuguesa and Barinas.

Calomys species are the Argentine and Bolivian reservoirs; the house mouse and ticks are not involved.

Transfusion of immune convalescent plasma is established for Argentine haemorrhagic fever and reduces mortality substantially when given within roughly the first week.

It is not a general treatment for the other arenaviruses, and its benefit depends on early administration.

Machupo virus causes Bolivian haemorrhagic fever, identified in 1963 by Karl Johnson’s team during an outbreak in the Beni region and carried by the rodent Calomys callosus.

The other diseases are caused by different arenaviruses.

Control of the New World haemorrhagic fevers depends chiefly on the antibody response, which is why passive transfer of immune plasma is effective in Argentine haemorrhagic fever.

This contrasts with Lassa fever, where T-cell immunity is decisive; the other mechanisms are not the main route of recovery.

Sabia virus is known from only a few cases, including laboratory-acquired infections, one following a centrifuge accident, which underlined the hazard of handling these viruses.

It has not caused a large epidemic or the other listed events.

Tacaribe virus was isolated from bats rather than rodents and does not cause human disease, making it a useful and safer laboratory surrogate for its dangerous clade B relatives.

The other statements are untrue of it.

A 2019 cluster of Chapare virus in La Paz spread to healthcare workers, with fatalities, showing that these viruses can transmit person-to-person and are not always dead-end infections.

They are rodent-borne, not mosquito-borne, and can cause severe disease and nosocomial risk.

The New World arenaviruses form the Tacaribe serocomplex and are carried by cricetid rodents of the Americas, each virus tied to a particular reservoir species.

Murid mice carry the Old World arenaviruses; ticks, mosquitoes and bats are not the reservoirs.

Junin virus is maintained by the drylands vesper mouse Calomys musculinus, a field rodent of the Argentine pampas, which is why Argentine haemorrhagic fever tracks the maize harvest.

Mastomys is the Lassa reservoir and Zygodontomys the Guanarito reservoir; the house mouse and bats are not involved.

The incubation period is about 6 to 14 days, after which illness begins gradually rather than abruptly.

The other intervals are too short or too long.

Junin virus, the cause of Argentine haemorrhagic fever, was the first of the group identified, in the late 1950s.

Machupo followed in 1963, and Guanarito, Sabia and Chapare emerged later.

A clade B virus can infect people when its GP1 subunit engages the human form of transferrin receptor 1, not only its rodent host’s version.

This fit to the human receptor, rather than any of the other mechanisms, determines the capacity to spill over.

MCQ
A pathogenic New World arenavirus most likely enters cells using which receptor?
- A. Alpha-dystroglycan
- B. Sialic acid
- C. The CD4 molecule
- D. Transferrin receptor 1
- E. Angiotensin-converting enzyme 2
Show answer
Correct answer: D
The pathogenic New World (clade B) arenaviruses enter cells through transferrin receptor 1, whereas the Old World viruses and clade C use alpha-dystroglycan.

Sialic acid, CD4 and angiotensin-converting enzyme 2 are receptors for other viruses, not the arenaviruses.
MCQ
About a tenth of patients treated with immune plasma for Argentine haemorrhagic fever develop:
- A. An immediate and severe transfusion-related anaphylactic reaction
- B. Chronic renal failure
- C. A late, self-limiting neurological syndrome with cerebellar signs
- D. Permanent bilateral blindness
- E. Secondary bacterial pneumonia
Show answer
Correct answer: C
About a tenth of patients given immune plasma for Argentine haemorrhagic fever develop a late, self-limiting neurological syndrome with fever and cerebellar signs, some weeks after apparent recovery.

The other complications are not features of this treatment.
MCQ
Acute-phase diagnosis of a New World arenaviral haemorrhagic fever relies on:
- A. IgG antibody serology performed alone
- B. Routine blood culture on standard bacteriological media
- C. Clinical features alone, with no laboratory testing
- D. RT-PCR and antigen detection, under maximum containment
- E. A rapid over-the-counter urine antigen dipstick performed at home
Show answer
Correct answer: D
Acute diagnosis rests on reverse transcription polymerase chain reaction and antigen detection, performed under maximum containment, because the antibody response develops too slowly to help early.

Serology is for later or for surveillance, and dengue is an important early differential.
MCQ
Compared with Lassa fever, the South American haemorrhagic fevers characteristically show:
- A. A more prominent neurological picture, with a normal or mildly raised AST
- B. Marked jaundice together with very high serum aminotransferase concentrations
- C. No haematological changes at all
- D. A vesicular rash like chickenpox
- E. Isolated renal failure without fever
Show answer
Correct answer: A
The South American haemorrhagic fevers carry a more prominent neurological picture than Lassa, with thrombocytopenia and leucopenia but a normal or only mildly raised aspartate aminotransferase.

Marked hepatitis, an absence of blood-count changes, a chickenpox-like rash and isolated renal failure are not their pattern.
MCQ
Guanarito virus causes Venezuelan haemorrhagic fever and is carried by:
- A. The Argentine drylands vesper mouse Calomys musculinus
- B. The rodent Calomys callosus
- C. The cane mouse Zygodontomys brevicauda
- D. The house mouse
- E. Ixodid ticks
Show answer
Correct answer: C
Guanarito virus, the cause of Venezuelan haemorrhagic fever, is carried by the cane mouse Zygodontomys brevicauda in the states of Portuguesa and Barinas.

Calomys species are the Argentine and Bolivian reservoirs; the house mouse and ticks are not involved.
MCQ
Immune convalescent plasma is an established treatment for which disease, and works best when given:
- A. Bolivian haemorrhagic fever, given only well after the second week
- B. Argentine haemorrhagic fever, given within the first week
- C. Lassa fever, given at any stage of illness
- D. All arenaviral infections equally
- E. Chapare fever, given as prophylaxis
Show answer
Correct answer: B
Transfusion of immune convalescent plasma is established for Argentine haemorrhagic fever and reduces mortality substantially when given within roughly the first week.

It is not a general treatment for the other arenaviruses, and its benefit depends on early administration.
MCQ
Machupo virus, identified in 1963, causes:
- A. Argentine haemorrhagic fever
- B. Bolivian haemorrhagic fever
- C. Venezuelan haemorrhagic fever
- D. Brazilian haemorrhagic fever
- E. Lassa fever
Show answer
Correct answer: B
Machupo virus causes Bolivian haemorrhagic fever, identified in 1963 by Karl Johnson’s team during an outbreak in the Beni region and carried by the rodent Calomys callosus.

The other diseases are caused by different arenaviruses.
MCQ
Recovery from a New World arenaviral haemorrhagic fever depends chiefly on:
- A. The interferon response alone
- B. Complement fixation
- C. Direct viral clearance by neutrophils
- D. The antibody response
- E. Natural killer cells alone
Show answer
Correct answer: D
Control of the New World haemorrhagic fevers depends chiefly on the antibody response, which is why passive transfer of immune plasma is effective in Argentine haemorrhagic fever.

This contrasts with Lassa fever, where T-cell immunity is decisive; the other mechanisms are not the main route of recovery.
MCQ
Sabia virus is notable for having caused:
- A. A large sustained community epidemic across the rural Argentine pampas
- B. Chronic viral hepatitis
- C. Laboratory-acquired infections, one after a centrifuge accident
- D. A vaccine-derived outbreak
- E. Widespread sustained person-to-person spread
Show answer
Correct answer: C
Sabia virus is known from only a few cases, including laboratory-acquired infections, one following a centrifuge accident, which underlined the hazard of handling these viruses.

It has not caused a large epidemic or the other listed events.
MCQ
Tacaribe virus is unusual among the clade B arenaviruses because it:
- A. Causes by far the most severe of all the haemorrhagic fevers
- B. Is carried by Calomys field rodents
- C. Uses alpha-dystroglycan as its receptor
- D. Is a bat-associated virus that does not cause human disease
- E. Has a licensed human vaccine
Show answer
Correct answer: D
Tacaribe virus was isolated from bats rather than rodents and does not cause human disease, making it a useful and safer laboratory surrogate for its dangerous clade B relatives.

The other statements are untrue of it.
MCQ
The 2019 Chapare virus cluster in La Paz demonstrated that these viruses:
- A. Are transmitted solely by the bite of infected mosquito vectors
- B. Do not spread between people
- C. Pose no risk to healthcare workers
- D. Cause only a mild and self-limiting febrile illness
- E. Can spread person-to-person in healthcare settings
Show answer
Correct answer: E
A 2019 cluster of Chapare virus in La Paz spread to healthcare workers, with fatalities, showing that these viruses can transmit person-to-person and are not always dead-end infections.

They are rodent-borne, not mosquito-borne, and can cause severe disease and nosocomial risk.
MCQ
The New World arenaviruses are carried in nature by:
- A. Murid mice of the African savanna region
- B. Ixodid ticks
- C. Culex mosquitoes
- D. Fruit bats of the Americas
- E. Cricetid rodents of the Americas
Show answer
Correct answer: E
The New World arenaviruses form the Tacaribe serocomplex and are carried by cricetid rodents of the Americas, each virus tied to a particular reservoir species.

Murid mice carry the Old World arenaviruses; ticks, mosquitoes and bats are not the reservoirs.
MCQ
The reservoir of Junin virus (Argentine haemorrhagic fever) is:
- A. The peridomestic house mouse
- B. The drylands vesper mouse Calomys musculinus
- C. The multimammate rat Mastomys natalensis
- D. The South American cane mouse Zygodontomys brevicauda
- E. A fruit bat
Show answer
Correct answer: B
Junin virus is maintained by the drylands vesper mouse Calomys musculinus, a field rodent of the Argentine pampas, which is why Argentine haemorrhagic fever tracks the maize harvest.

Mastomys is the Lassa reservoir and Zygodontomys the Guanarito reservoir; the house mouse and bats are not involved.
MCQ
The usual incubation period of the South American haemorrhagic fevers is:
- A. Less than 24 hours
- B. 1 to 2 days
- C. 6 to 12 weeks
- D. Several months
- E. 6 to 14 days
Show answer
Correct answer: E
The incubation period is about 6 to 14 days, after which illness begins gradually rather than abruptly.

The other intervals are too short or too long.
MCQ
Which was the first New World arenavirus to be characterised?
- A. Junin virus, the cause of Argentine haemorrhagic fever
- B. Machupo virus, identified during a 1963 Bolivian outbreak
- C. Guanarito virus
- D. Sabia virus
- E. Chapare virus, the most recently identified agent
Show answer
Correct answer: A
Junin virus, the cause of Argentine haemorrhagic fever, was the first of the group identified, in the late 1950s.

Machupo followed in 1963, and Guanarito, Sabia and Chapare emerged later.
MCQ
Why can a clade B New World arenavirus infect humans?
- A. Its GP1 also engages the human transferrin receptor 1
- B. It uses the CD4 receptor on human helper T lymphocytes
- C. It binds the human alpha-dystroglycan receptor
- D. It is transmitted directly between people
- E. It integrates into the human genome
Show answer
Correct answer: A
A clade B virus can infect people when its GP1 subunit engages the human form of transferrin receptor 1, not only its rodent host’s version.

This fit to the human receptor, rather than any of the other mechanisms, determines the capacity to spill over.