What are the other Names for this Condition? (Also known as/Synonyms)

• Brazilian Haemorrhagic Fever
• São Paulo Hemorrhagic Fever

What is Brazilian Hemorrhagic Fever? (Definition/Background Information)

• Brazilian Hemorrhagic Fever is an emerging viral illness in certain regions of Brazil in South America. It is one of the South American hemorrhagic fevers which was discovered in 1990 that reemerged in 2020
• It is caused by Sabiá virus (SABV) which is an RNA virus belonging to Arenaviridae family of viruses and clade B of South American hemorrhagic fever arenaviruses. It is a newly emerged virus and due to lack of immunity in the human population, it has a potential to cause severe life-threatening disease
• Rodents are the likely natural reservoirs of the virus. They carry the virus asymptomatically without being affected and transmit the virus to humans. However, the exact (rodent) species that transmit the virus is yet to be identified
• Due to scarcity of knowledge about the virus and the disease it causes, there is not much information about how to prevent Brazilian Hemorrhagic Fever. It is frequently misdiagnosed as other hemorrhagic diseases, especially yellow fever
• A definitive diagnosis of Brazilian Hemorrhagic Fever is possible only through contemporary molecular techniques, such as polymerase chain reaction technique, which help detect the genetic material of the virus
• There are no antiviral treatments presently available for Brazilian Hemorrhagic Fever, and therefore, only symptomatic treatment is administered. Prognosis is generally poor in the absence of early treatment

Who gets Brazilian Hemorrhagic Fever? (Age and Sex Distribution)

• Individuals of any age group and both male and female genders can be affected by Brazilian Hemorrhagic Fever
• To date, only a few cases of this infection have been reported in humans, worldwide. Before its reemergence in 2020, only four cases had been reported since its first case in 1990. Two of these infections were naturally acquired and were found in Brazil, whereas the other two were acquired due to occupational exposure in reference laboratories - one each in Brazil and USA
• The exact burden of Sabiá virus (SABV) infection is not known due to insufficient population studies in Brazil. However, it is possible that the condition is frequently misdiagnosed as other hemorrhagic diseases and may remain underdiagnosed

What are the Risk Factors for Brazilian Hemorrhagic Fever? (Predisposing Factors)

The possible risk factors for Brazilian Hemorrhagic Fever (similar to other South American hemorrhagic fevers) may include:

• Living in or traveling to endemic areas in Brazil
• Suburbanization (peripheral expansion of human population into the forest areas), hunting, camping, and other hobbies which increase the possibility of exposure to unknown species of viruses and animals
• Providing care for individuals with the disease: Medical professionals and family members of infected individuals may have a higher risk
• Procedures that can spray particles of the infected person’s body fluids, such as during chest compressions, cardiopulmonary resuscitation (CPR), intubation, mechanical ventilation, and endoscopies
• Doing research on contaminated samples

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Brazilian Hemorrhagic Fever? (Etiology)

The Brazilian Hemorrhagic Fever is a severe and deadly disease transmitted by rodents to humans.

• It is caused by Sabiá virus (SABV) which belongs to Arenaviridae family and clade B of South American hemorrhagic fever arenaviruses. This is an RNA virus, which means that it has ribonucleic acid (RNA) as its genetic material
• Rodents are the likely natural reservoirs of this virus similar to other South American hemorrhagic fever arenaviruses. They can carry the virus asymptomatically without being affected and transmit it to humans. However, the exact species that carry the virus has not been yet identified
• The possible modes of transmission from rodents to humans include:
  • Inhalation of rodent excreta stirred in air
  • Consumption of food contaminated with rodent excreta
  • Contact with rodent excreta through breech in skin (e.g., needlestick, bite, or scratch) or mucous membranes (splash to eyes, nose, or mouth) 
  • Bites and scratches by infected rodents
• As there have been only few cases, there is no data regarding human-to-human transmission

What are the Signs and Symptoms of Brazilian Hemorrhagic Fever?

Brazilian Hemorrhagic Fever is clinically similar to other viral hemorrhagic fevers. It begins with a prodromal period characterized by a nonspecific flu-like illness. Early beginning of supportive therapy can aid in a full recovery of the individual, but the condition can be severe and life-threatening if not treated promptly.

The prodromal phase produces flu-like signs and symptoms which may easily be confused with other illnesses, and this may lead to a delay in seeking medical attention. These include:

• Fever
• Fatigue, malaise, and weakness
• Headache
• Pain behind the eyes
• Muscle and join pains
• Low-back pain
• Stomach pain
• Anorexia
• Nausea and vomiting
• Cough and sore throat
• Conjunctivitis
• Diarrhea and dehydration
• Dizziness
• Irritability
• Decrease in blood cell count

If medical attention and treatment (basically fluid control) are not received soon after the appearance of initial symptoms, the individual can eventually develop severe life-threatening symptoms, including bleeding manifestations in various organs. These include:

• Petechial rash due to bleeding in skin
• Conjunctival petechiae due to bleeding in eyes
• Bleeding from the gums and nose
• Blood in vomitus, cough, urine, or stools
• Bleeding from sites of vein puncture
• Fluid in lungs
• Low blood pressure
• Liver damage
• Massive internal bleeding and hypovolemic shock
• Neurological signs such as tremors, muscle spasms, seizures, delirium, and coma

How is Brazilian Hemorrhagic Fever Diagnosed?

To make a diagnosis of Brazilian Hemorrhagic Fever, it is important for the healthcare professional to have a high index of suspicion and collect information about the following:

• Clinical data including signs and symptoms, physical examination, and course of the illness including changes in blood chemistry
• Travel to endemic areas in Brazil
• History of exposure to rodents in the endemic areas
• History of contact with individuals with suggestive symptomatology

The following tests, although performed at only designated centers, such as the US-based Centers for Disease Control and Prevention, can be used to confirm the diagnosis:

• Contemporary molecular tests, such as polymerase chain reaction (PCR), which is a highly specific test
• Virus isolation in cell culture: Specific test that requires highly sophisticated laboratories with advanced biosafety mechanisms
• Serological tests, such as enzyme-linked immunosorbent assay (ELISA), are not specific and can cross-react with other infections

Other conditions which may present with similar signs and symptoms are yellow fever, Argentine hemorrhagic fever, Bolivian hemorrhagic fever, malaria, dengue, leptospirosis, Hantavirus, influenza, etc.

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Brazilian Hemorrhagic Fever?

As Brazilian Hemorrhagic Fever symptoms worsen, life-threatening complications may occur such as:

• Multiple organ failure
• Severe bleeding
• Hypovolemic shock

Not much is known about the long-term complications of the disease.

How is Brazilian Hemorrhagic Fever Treated?

Currently, there are no approved antiviral treatments for individuals with Brazilian Hemorrhagic Fever. Only supportive therapy is provided to individuals to help them cope with the disease and its symptoms. These include:

• Fever control
• Pain relief
• Fluid and electrolytes maintenance
• Oxygen and blood pressure maintenance
• Transfusions for bleeding disorders 

How can Brazilian Hemorrhagic Fever be Prevented?

Due to scarcity of knowledge about the virus and its reservoir, there is not much information about how to prevent this infection. Currently, there are also no approved vaccines available to prevent this infection.

However, certain general preventive measures used for other arenaviruses can be helpful, and these include:

• Avoiding exposure to rodents and their body fluids and droppings
• Rodent control using rodenticide and rodent traps in and around homes
• Avoiding contact with body fluids (e.g., saliva, blood, respiratory secretions, semen, urine, etc.) of affected individuals, both sick and recovering, until their tests are negative for the virus

• Strictly isolating suspected or confirmed individuals with the disease
• Following all infection-control procedures in healthcare and other settings, including the use of protective clothing, masks, and gloves
• Being careful while handling rodents and patient samples, especially during research

Other preventative measures may include:

• Frequent handwashing
• Ensuring proper disposal of contaminated materials
• Avoiding or limiting travel to the endemic regions in Brazil, especially the forested areas

What is the Prognosis of Brazilian Hemorrhagic Fever? (Outcomes/Resolutions)

• Brazilian Hemorrhagic Fever is an extremely severe disease which can quickly lead to death due to the lack of specific treatment and absence of immunity in the population
• However, individuals who seek medical attention and receive treatment (fluid control) soon after appearance of the first symptoms are known to have recovered fully without any long-term complications

Additional and Relevant Useful Information for Brazilian Hemorrhagic Fever:

• Sabiá virus (SABV) is named after the district where the first identified case (individual) of Brazilian hemorrhagic fever lived, namely Sabiá
• In South America, viral hemorrhagic fever is caused by Junin virus in central Argentina (Argentine hemorrhagic fever), Machupo and Chapare viruses in Bolivia (Bolivian hemorrhagic fever), Guanarito virus in western Venezuela (Venezuelan hemorrhagic fever), and Sabia virus in Brazil (Brazilian hemorrhagic fever). These diseases are collectively known as the South American hemorrhagic fevers (SAHF). In each case, the disease tends to occur in a limited region of the country