Arenaviruses Clinical Presentation

Updated: May 12, 2019
  • Author: Sandra G Gompf, MD, FACP, FIDSA; Chief Editor: Pranatharthi Haran Chandrasekar, MBBS, MD  more...
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Clinically apparent arenavirus infections typically present with fever, headache, myalgia, and malaise. Relative bradycardia and hyperesthesia are common as well. Thereafter, the various diseases pursue different courses as follows:

Lymphocytic choriomeningitis virus

While most LCMV infections are subclinical or result in mild febrile syndromes, biphasic illness with aseptic meningitis may occur. The illness can be biphasic.

After an incubation period of 8-13 days, a nonspecific syndrome of fever, weakness, malaise, joint and/or lumbar pain, nausea and vomiting, and cough may begin. Parotitis or testicular pain may also develop. This phase may last up to a week.

After a few days' respite, a second phase of aseptic meningitis may follow, with fever, severe headache, and neck stiffness. More severe disease may manifest as encephalitis, with delirium and neurologic motor and sensory disturbances. [7, 8]

Lassa fever

Eighty percent of cases are mild and may go undiagnosed. Severe multisystem disease is believed to occur in 20% of total infections.

Incubation period is 1-3 weeks.

Illness begins insidiously with a nonspecific syndrome of fever, weakness, malaise, and joint and/or lumbar pain.

In severe cases, illness progresses to include prostration, dehydration, abdominal pain, and facial or neck edema. [9, 10]

South American hemorrhagic fevers

Junin and Machupo viruses are similar in severity, and anecdotal reports suggest that Guanarito infections may be somewhat more severe overall.

The illnesses begin somewhat insidiously with fever, malaise, myalgia, and lumbar pain.

Progression may occur over 3-4 days, with prostration, unremitting fever, and mucosal bleeding. Hemorrhage along the gingival margins is characteristic.

After 1-2 weeks, most patients improve, but approximately one third progress to profound cutaneous and mucosal hemorrhages, delirium, and convulsions or a combination of CNS and bleeding findings. Capillary leak syndrome also may occur. [10]



The major physical examination findings observed in the major Arenavirus illnesses are as follows:

Lymphocytic choriomeningitis virus

On examination during the initial phase, findings may include fever, generalized lassitude, conjunctival injection, facial flushing, generalized lymphadenopathy, and orthostatic hypotension.

During the second phase, fevers, meningismus, and papilledema may be observed, with overt lymphocytic pleocytotic meningitis with elevated cerebrospinal (CSF) protein. Significantly elevated opening pressure may be observed on lumbar puncture. In the presence of myelitis, paralysis and paresthesias may be detected depending on the level at which the spinal cord is affected.

Serum aminotransferases may be elevated.

Lymphopenia, thrombocytopenia, and defects of qualitative platelet function are found during this stage. [8]

Lassa fever

Most cases manifest as mild fever, headache, and malaise.

In individuals with severe disease, respiratory distress and shock may occur. Facial edema, as well as hemorrhage of gums, nose, and mouth, may be observed, in addition to severe nausea, vomiting, and chest, back, and abdominal pain. CNS symptoms may include tremors, confusion, encephalopathy, and seizures. Focal neurologic signs are absent.

Cerebrospinal fluid (CSF) is normal.

Serum aminotransferases may be elevated. Lassa fever stands alone among causes of viral hepatitis to have aspartate aminotransferase (AST) levels substantially higher than alanine aminotransferase (ALT) levels. This pattern has been classic for alcoholic hepatitis. Bleeding is seen in only 15-20% of patients, it usually is limited to mucosal surfaces, and it is limited in severity. [10]

South American hemorrhagic fevers

Conjunctival injection, facial flushing, generalized lymphadenopathy, and orthostatic hypotension are common signs.

Many patients have a petechial and/or vesicular palatal enanthem and skin petechiae.

At the point of further progression, CNS signs can include tremor of hands and tongue, hyperesthesias, decreased deep-tendon reflexes, and lethargy.

Especially with deteriorating illness, leukopenia and thrombocytopenia are common but aminotransferase elevations are uncommon. [10]



Lymphocytic choriomeningitis virus

The mortality rate of LCM is low (1%). Complications of LCM may include chronic neurologic deficits, including deafness.

Pregnant women with LCMV infection may pass it to the fetus. Spontaneous abortion may occur in the first trimester. In later trimesters, visual defects, intellectual disability, and hydrocephalus have been reported. [8]

Lassa virus

The most common complication of Lassa fever, regardless of severity, is deafness, which affects about 30% of infected individuals. It is often permanent.

Pregnancy is a risk factor for mortality, as well as fetal loss, which occurs in up to 95% of cases.

Death occurs in 15%-50% of all cases. [10]

South American hemorrhagic fevers

The mortality rate associated with Machupo, Junin, and other New World arenaviruses is up to 20%. [1]