Lassa Fever

Lassa Fever: Causes, Symptoms, Diagnosis And Treatment

Lassa fever refers to the viral disease spread by a type of rat. It is common in several regions of West Africa. You cannot ignore the hemorrhagic fever as it can result in fatal complications. Patients suffering from the fever face a high risk of death as it can result in severe bleeding. Unfortunately, the disease also referred to as LHF (Lassa Hemorrhagic Fever) triggers no symptoms. So, it is difficult to get treatment early. With no medical intervention, it affects vital organs like kidneys, spleen, or liver. Several Western African countries have suffered due to LHF. It is an endemic as it affects around one to three lakh people in the regions. The disease is also the main cause of death in the regions with approximately five thousand infected people succumbing to death.

The disease infects people who visit the Western African region. So, the spread of the disease occurs due to international travel, which increases the risk of spreading LHF from one country to another. Areas of Western African regions like Sierra Leone and Liberia have recorded 10% to 16% of hospital admission due to the disease. So, the disease has a widespread impact in such areas. Read ahead to know more about LHF and the methods to control it.

About Lassa Fever

Several records indicate the description of the disease around the 1950s. But, the remained unidentified until 1969. The disease affected two missionary nuns in Nigeria, making it the first official record of the disease. The name of the disease is derived from the name of the village of Lassa. The first recorded case came from the village. The virus causing the disease belongs to the family of Arenaviridae. It is a single-stranded RNA virus that spreads through rodents. The virus is carried by the rats belonging to M.natalensis (multimammate rate). These rats are the most common rodent species in equatorial Africa. So, the rats are found in several sub-Saharan African regions. It is a zoonotic disease, which means humans usually contract the disease from animals. While the Mastomys rats triggering the disease may not become infected. But, they spread the virus through contaminated urine or feces.

About Lassa Fever

The disease is serious because people infected by the disease may not show any symptoms or have varying symptoms. Variable symptoms make detection impossible. So, it results in an escalation of the disease, resulting in multi-organ failure and death. But, when the disease is uncovered in a community, it requires prompt isolation of affected patients. It helps with effectively preventing and control practices. So, the rigorous contact tracing can stop outbreaks of LHF.

List Of Lassa Fever Endemic

List Of Lassa Fever Endemic

The disease is a known endemic in several western African countries like the following:

  • Benin (First discovery of the disease occurred in 2014)
  • Guinea
  • Nigeria
  • Ghana (Diagnosed for first time in 2011)
  • Liberia
  • Mali (discovered for the first time in 2009)
  • Sierra Leone

In the above-mentioned regions, the high population of Mastomys rat increases the risk. The rat population also increases the risk of spreading the disease to its neighboring countries.

Causes Of Lassa Fever

Causes Of Lassa Fever

Lassa Fever (LHF) is an illness caused due to Lassa virus. The virus is the hemorrhagic fever causing a virus having a single-stranded RNA. It belongs to the Arenaviridae family. The acute febrile illness caused by the virus can last from one to four weeks. It mostly occurs in West African areas and beyond. LHF causes more than five thousand deaths every year. It is triggered by an infected Mastomys rat, which spreads the virus through its excretion. Due to the rapid breeding of rodents, the disease spread to a large population.

Risk Factors Associated With Lassa Fever

Are you at risk of Lassa fever? The disease mostly affects people who come in close contact with the Lasa virus. It occurs when:

  • You live or visit West African regions
  • Health professionals who deal with LHF infected people without proper PPE

Transmission Of Lassa Fever

The Lassa virus causes the fever and the rodent belonging to Mastomys Natalensis (multimammate rate) acts as the host or reservoir of the disease. Once the rodent becomes infected with the virus, it can pass the virus through its excretion feces or urine) for a long time. So, Mastomys rats infected with the virus can excrete virus throughout its life. Since the type of rodents breed frequently and produce several offspring, the risk of exposure is higher. So, people living or visiting savannas and forests of East, West, and Central Africa face the high risk of becoming infected with the disease. Since Mastomys rodents readily colonize in the area with food storage or human homes, it increases the risk of efficient transmission of Lassa virus from the infected rodents to people.

Transmission Modes

LHF occurs when the virus spreads from the infected rodents to the humans in the following methods:

Direct Transmission

In the majority of the cases, the transmission of viruses causing LHF occurs due to inhalation or ingestion from contamination urine and droppings by the infected Mastomys rodents. Direct contact with these materials can result in transmission. It can also occur by touching soiled objects as well as food contaminated by the feces or urine by the infected rodents. It can also enter the human bloodstream through open cuts and sores. The direct transmission occurs in the following methods:

  • Poorly stored or leftover human food items that come in contact with the infected Mastomys rodents.
  • Consuming infected Mastomys rodents when they are caught and prepared.
  • Inhaling air contaminated with the infected rodent excretions during cleaning activities. The airborne transmission is common when you sweep the area containing infected rodent excretions.

Person-To-Person Transmission

The transfer of the virus from one person to another is referred to as nosocomial transmission in the health settings. The virus can also spread from one person to another through the following from a virus-infected person:

  • Excretions of virus-infected individual
  • Blood
  • Body fluid secretion
  • Tissue
  • Contaminated medical equipment (like reused needles)

Healthcare workers are prone to contracting the virus through the above-mentioned methods. It is because of not using or improper use of PPE (proper personal equipment). But, the transmission of the virus does not occur through casual skin contact. So, if you just touch a person without exchanging body fluids, then you face no risk of developing LHF.

Symptoms Linked To Lassa Fever

Lassa Fever

Lassa fever refers to an acute viral hemorrhagic disease. A person exposed to the virus due to their travel or stay in West Africa can see the symptoms after six to twenty-one days after getting the infection. A person gets the infection due to coming in contact with the contaminated household items or food. It contaminates with rodent feces or urine. The person-to-person transmission also occurs, triggering symptoms. But, a majority of people exposed to the virus never show any significant symptoms. They only feel the following:

But, a small population exposed to the virus show different signs. It includes:

People mostly observe the signs when the condition becomes severe. So, 1% of the population affected by LHF can experience fatal effects. So, people who are hospitalized for the disease with severe symptoms ultimately face death (15%-20% cases). Death occurs to the infected person within two weeks of the onset of symptoms. It mostly occurs due to multiple organ failure. The condition is also dangerous for pregnant women, especially in their later stages of pregnancy. It can lead to spontaneous loss of the baby or other complications.

Complications Associated With Lassa Fever

People who suffer from LHF can face severe complications. Without medical intervention, your risk of facing serious complications like death increases. Patients who suffer from the disease experience the following complications:


It is the common complication associated with the illness. Depending on the person it affects, the degree of deafness varies. But, approximately one-third of the people affected by LHF suffer from hearing issues. In some cases, the deafness is permanent. The severity of the disease is not a factor in developing deafness. It develops in people who experience mild forms as well as the severe forms of the illness.

Pregnancy Complications

Pregnant women face a high risk of death or losing their child in the womb when they suffer from Lassa fever. The disease in the third trimester leads to spontaneous abortion in 95% of the cases. Without timely intervention, expectant mothers face the risk of death.


Death is the fatal complication associated with the disease. Most people who seek medical services have a severe form of the disease. So, their health deteriorates and results in death. It is because the symptoms of LHF varies from person to person. The non-specific symptoms make clinical diagnosis difficult. The fever also causes occasional epidemics. In such cases, the fatality rate reaches an alarming rate of 50%.

Diagnosing Lassa Fever

In the initial stages, diagnosing the disease conclusively can pose a problem to the healthcare professionals. It is because the disease has symptoms that mimic other viral hemorrhagic fevers. So, your doctor first needs to eliminate the following disease:

Apart from the signs resembling other diseases, detecting LHF in people becomes difficult as the symptom varies from one person to another. But, the following methods can help your doctor diagnose the problem:

Physical Assessment

Your doctor can assess your symptoms. A thorough physical assessment can give an idea to the doctor.

Travel History

Your doctor also asks about travel history. If you have recently visited areas affected or suffered an outbreak of Lassa fever, then you need to inform your doctor.

Lab Testing

These tests can only offer definitive ideas regarding the disease. Other methods can never conclusively determine Lassa fever. So, your doctor suggests lab tests to detect the problem. Since the handling of specimens can pose a huge risk, only specialized institutions can conduct such tests. So, find a lab that handles specimens with care. The tests used to detect the problem conclusively are:


ELISA stands for Enzyme-Linked Immunosorbent Serologic Assays. The tests help detect Lassa antigens along with IgM and IgG.


RT-PCR refers to a Reverse transcription-polymerase chain reaction (RT-PCR), which used to detect the disease in its early stages.

Treatment For Lassa Fever

Unfortunately, no treatment is available for LHF. With several health organizations around the world working to develop vaccination, the hope to develop an effective preventive measure exists. But, until 2019, no vaccination has offered successful results to avoid the disease. The treatment of LHF focuses on managing the symptoms and preventing the signs from escalating. With early diagnosis, it becomes easier to manage the symptoms and improve the chances of survival. The treatment options available for dealing with LHF are:

Use Of Ribavirin


People who develop symptoms of LHF need to take ribavirin. It is the antiviral drug that helps in fighting the virus. While the working remains unclear, the medication used early in the disease offers positive results. So, patients taking it within the first six days of the illness can find relief. Unfortunately, the antiviral medication is not available in the worst areas affected by the fever. Due to its limited access and the side effects associated with the disease, the medication is not a perfect solution for the problem. The use of the medication can cause toxicity and mutations (teratogenic). So, you can only take it after a doctor prescribes it after careful analyses of the symptoms.

Other Treatment Options

Most patients suffering from LHF can suffer from vomiting, diarrhea or dizziness. Therefore, the other treatment options focus on relieving the symptoms and associated distress. So, your doctor can suggest the following to maintain regular body function and offer relief:

  • Manage fluid levels to avoid dehydration. So, you are provided enough fluids to rehydrate your body. Rehydration also ensures electrolyte balance to offer you relief from the symptoms.
  • Enough oxygenation is provided to the body for making your lungs, as well as the circulatory system, work properly.
  • Monitor blood pressure to avoid it from decreasing drastically and triggering life-threatening problems.
  • In severe cases, patients suffer from bleeding. So, they require a blood transfusion to avoid any complications due to the loss of blood.

Treating Pregnant Women

Pregnant women who suffer from LHF in the latter part of their pregnancy can suffer serious complications. So, to avoid any harm to the health of the mother, the doctor suggests emergency C-Section delivery improves the chances of survival. It is also necessary as the virus can affect the placenta and other significant vascular tissues, making it difficult for the unborn baby to survive. Unfortunately, even with early medical interventions, only one in ten fetuses survive. So, the primary focus is always on avoiding complications to the mother. After delivery, the women undergo the same treatment as other sufferings from the disease.

Developing Vaccination

While talking about the treatment options, you must also know the status of the vaccine. Currently, several reliable sources indicate the work going on to develop an effective vaccine to prevent Lassa fever. The vaccination developed by the joint efforts from CEPI (Coalition for Epidemic Preparedness Innovations) and Themis Bioscience has undergone phase II trials. The research, as well as development on developing vaccination, requires acceleration to avoid the serious outbreak of the disease.

Preventing Lassa Fever

To prevent Lassa fever, it is important to maintain hygiene. You need to take essential steps to control the rat population triggering the disease. While the disease-causing Mastomys rat population is so widespread that it is impossible to eradicate with ease. So, the following preventive measures can avoid the disease and associated complications.

Prevent Rodents

The World Health Organization (WHO) and other organizations work to raise awareness in areas where Lassa fever is a threat. Community hygiene is essential to prevent rodents from spreading the disease. The effective measures include:

  • Storing all the grains needed for your family as well as other foodstuffs in rodent-proof containers.
  • Disposing garbage is essential to keep the surroundings clean. So, dispose of garbage at a far place from the home. It reduces the chances of rats coming near your home.
  • Keep the household clean. Clutters and unhygienic home surroundings can increase the rat population.
  • Every susceptible household must have a cat to prevent the rat population from increasing.

The Mastomys rats are found in abundance in the endemic prone areas. So, it is not possible to eliminate them from the surrounding areas. But, the above-mentioned steps can reduce the population to an extent.

Precautions At Home Setting

Apart from taking steps to prevent the rodent population, it is important to follow some steps to prevent the infection like:

  • Washing hands regularly to prevent the spread of the virus after touching a contaminated surface. Regular hand washing can reduce the transmission of the virus.
  • Avoiding contact with body fluids or blood while caring for infected people. If a close family member suffers from the disease, then always maintain caution.
  • If the infected person dies, then follow safe burial practices. Follow the suggested procedure without fail to prevent the disease from transmitting to others.

Preventing Lassa Fever In Healthcare Setting

People who work in the healthcare sector are more prone to infection. It is because they come in contact with the infected or suspected infection cases regularly. To avoid transmission of diseases, healthcare professionals must follow the suggested guidelines:

Cases With Unclear Diagnosis

At the time, you care for people who have not received their diagnosis yet. In such cases, it is important to follow the standard infection and control precautions suggested irrespective of the diagnosis. So, you need to follow the guidelines suggested below:

  • Maintain basic hand hygiene by washing your hands frequently using soap and water. Use a hand sanitizer containing 60% alcohol.
  • Follow respiratory hygiene by using a facemask or face shield. It restricts the transmission of the virus through contaminated fluid droplets when the infected person coughs or sneezes.
  • It is important to use personal protective equipment (PPE) to block splashes of infected body fluids like blood. Using PPE also prevents healthcare professionals from coming into contact with infected materials.
  • Healthcare workers need to follow safe injection practices. It means they need to take injections to ensure the safety of patients and providers. It means avoiding reusing syringes, prevent contamination of multi-dose vials, ensure cleaning of finger-stick devices and blood measuring devices, as well as, other safety procedures to avoid transmission of viruses.
  • To prevent the spread of LHF, WHO recommends safe burial practices. While it is an emotional time for family members, to avoid the spread of disease, traditional rituals need modification. So, allowing fewer people to handle the dead bodies and making sure only a professional trained team to safely buries the body prevents the spread of the disease.

Cases With Confirmed Diagnosis

Healthcare professionals treating or caring for patients with a confirmed diagnosis of the disease need to implement extra preventive measures. So, you need to follow the suggested guidelines:

  • Prevent any contact with contaminated body fluids or blood of the infected patients.
  • Avoid touching the surface or materials (like bedding and clothing) suspected of contamination.
  • Avoid close contact by maintaining distance (at least meter) from the patients suffering from viral fever.
  • Wear face protection (medical mask, face shield, and goggles) to avoid inhaling contaminated droplets when the patient coughs or sneezes.
  • Wear a clean, non-sterile gown with long sleeves as well as gloves (sterile ones for certain procedures) to avoid coming in contact with blood or body fluids.

Preventive Measure For Laboratory Workers

Laboratory works who take the sample for testing from the infected person are risk of infection. It is because of their frequent contact with the samples containing the virus. So, only highly trained staff must handle the sample taken from humans as well as animals for investigation. The lab diagnosing the problem must-have equipment and have maximum biological containment conditions.

Precaution While Treating Travelers

In rare cases, travelers who come from areas suffering from Lassa fever can export the disease to other people residing in other countries. But, the disease is not common like other infections like typhoid fever, malaria, or other tropical infections. So, healthcare professionals dealing with patients (with signs like high body temperature) who have returned from West Africa, especially if they have exposed themselves to the rural areas or hospitals with known cases of Lassa Fever need to immediately contact the local as well as international experts. Based on the advice and guidelines provided, it is essential for laboratory testing.


Diagnosing and treating Lassa fever promptly is necessary to avoid severe complications. Unfortunately, most people seldom develop symptoms. So, it can lead to liver, spleen or kidney problems. Instead of waiting for the signs to appear, consult a doctor if you face a high risk of contracting the virus. With early medical intervention, you can overcome severe and irreversible complications.

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