Arenaviruses are a family of RNA viruses primarily associated with rodents, their natural hosts. They are widespread and can cause various human illnesses. While they typically establish persistent, often asymptomatic infections in rodents, they can lead to severe and sometimes fatal diseases when transmitted to humans.
How Arenaviruses Spread to Humans
Arenaviruses are primarily transmitted to humans through contact with infected rodents or their excretions. The most common route is inhaling aerosolized particles from rodent urine, droppings, or saliva. Infection can also occur by ingesting contaminated food or water, or through direct contact with infected rodents or their waste, particularly if there are breaks in the skin.
Person-to-person transmission is less common, but it can occur with certain arenaviruses, such as the Lassa virus. This type of spread happens through direct contact with the bodily fluids of an infected person, including blood, urine, or semen. Casual contact, such as shaking hands or sitting near an infected individual, generally does not transmit these viruses. Healthcare settings can also pose a risk if proper infection control measures are not in place.
Arenavirus-Related Illnesses and Symptoms
Initial symptoms of arenavirus infections are often non-specific, resembling common viral illnesses. These can include fever, fatigue, muscle aches, and headache, making early diagnosis challenging.
As the disease progresses, more specific and severe symptoms may develop depending on the particular arenavirus involved. The incubation period for these infections ranges from 3 to 21 days, with an average of about 10 days.
Lassa fever
Lassa fever, caused by the Lassa virus, is an illness primarily found in West Africa. It is carried by multimammate mice and can manifest with symptoms like facial swelling, bleeding from the gums or nose, and in severe cases, neurological problems such as tremors or hearing loss. Lassa fever severity varies, from mild cases to severe hemorrhagic forms.
South American Hemorrhagic Fevers
South American Hemorrhagic Fevers are caused by several arenaviruses endemic to specific regions of South America. These include:
- Argentine hemorrhagic fever (caused by Junin virus)
- Bolivian hemorrhagic fever (caused by Machupo virus)
- Venezuelan hemorrhagic fever (caused by Guanarito virus)
- Brazilian hemorrhagic fever (caused by Sabia virus)
These illnesses are characterized by symptoms such as fever, muscle pain, and hemorrhagic manifestations, including bleeding under the skin or from mucous membranes. Some patients may also experience neurological complications.
Lymphocytic Choriomeningitis (LCM)
Lymphocytic Choriomeningitis (LCM) is caused by the Lymphocytic Choriomeningitis virus (LCMV), which is unique for its worldwide distribution. This virus is primarily carried by common house mice.
LCMV infection typically results in a less severe illness compared to the hemorrhagic fevers, often presenting as a flu-like illness or aseptic meningitis, an inflammation of the membranes surrounding the brain and spinal cord. In some instances, it can lead to more severe neurological disease, particularly in individuals with weakened immune systems.
Prevention and Rodent Control
Preventing arenavirus infection centers on minimizing contact with rodents and their excretions. Maintaining a clean environment, both indoors and outdoors, helps deter rodent populations from establishing themselves near human habitation.
At home, practical measures include sealing any holes or gaps in walls, floors, and foundations to prevent rodents from entering buildings. Food should be stored in rodent-proof containers, and garbage should be kept in tightly sealed bins, away from living areas.
When cleaning areas potentially contaminated with rodent droppings or urine, avoid stirring up dust, which could aerosolize virus particles. Instead, disinfect surfaces with a bleach solution or household disinfectant after wearing gloves and masks, then wipe clean with damp cloths or paper towels.
In endemic areas or when traveling to regions where these viruses are known to circulate, caution is advised. Avoid direct contact with rodents (dead or alive) and disturbing burrows or nests.
Travelers should also ensure that food and water sources are safe and protected from potential rodent contamination.
Diagnosis and Medical Management
Diagnosing an arenavirus infection involves clinical assessment, exposure history, and specific laboratory tests. Healthcare providers consider symptoms along with information about recent travel to common regions or any known rodent exposure.
Laboratory tests confirm the presence of the virus or detect antibodies produced by the body. These tests may include reverse transcription-polymerase chain reaction (RT-PCR) to identify viral genetic material or enzyme-linked immunosorbent assay (ELISA) to detect specific antibodies in blood samples.
Medical management for arenavirus infections primarily focuses on supportive care. This involves maintaining the patient’s hydration, balancing electrolytes, managing blood pressure, and ensuring proper organ function. Patients with severe symptoms may require intensive care, including respiratory support or dialysis if kidney failure develops.
The antiviral drug ribavirin has shown effectiveness in treating some arenavirus infections, particularly Lassa fever. For ribavirin to be most beneficial, it needs to be administered early in the course of the illness, and its effectiveness can vary depending on the specific arenavirus causing the infection.