LASSA FEVER IN WEST AFRICA

Lassa fever, also known as Lassa haemorrhagic fever (LHF), is a type of viral haemorrhagic fever caused by the Lassa virus. Many of those infected by the virus do not develop symptoms. When symptoms occur, they typically include fever, weakness, headaches, vomiting, and muscle pains. Less commonly there may be bleeding from the mouth or gastrointestinal tract. The risk of death once infected is about one percent and frequently occurs within two weeks of the onset of symptoms. Among those who survive about a quarter have hearing loss, which improves within three months in about half of these cases.

Nature of the disease

The disease is usually initially spread to people via contact with the urine or faces of an infected multimammate mouse. Spread can then occur via direct contact between people. Diagnosis based on symptoms is difficult. Confirmation is by laboratory testing to detect the virus’s RNA, antibodies for the virus, or the virus itself in cell culture. Other conditions that may present similarly include Ebola, malaria, typhoid fever, and yellow fever. The Lassa virus is a member of the Arenaria family of viruses.

Lassa fever is a major public health challenge in West Africa, with Nigeria bearing the highest burden. It is an acute viral haemorrhagic fever (VHF) caused by the Lassa virus. The natural reservoir for the virus is the Mastomys natalensis rodent (commonly known as the multimammate rat). Other rodents that carry the virus have also been identified.

Epidemiological data show that Lassa fever occurs throughout the year, but more cases are recorded during the dry season i.e. November through May.

This is an advisory to health care workers, to prevent person to person transmission of Lassa fever especially in health care settings.

How it’s spread

1. Direct contact with urine, faeces, saliva or blood of infected rodents.

2. Ingesting food and drinks contaminated with urine, faeces, saliva or blood of infected rats.

3. Contact with objects, household items or surfaces contaminated with urine, faeces, saliva or blood of infected rats.

4. Person-to-person transmission can also occur through contact with blood, urine, faeces, vomitus and other body fluids of an infected person, particularly in hospital environment where infection prevention and control practices are not optimal.

Signs and symptoms of Lassa fever:

The early stages of Lassa fever present initially like other febrile illness such as malaria. Symptoms of the disease generally include fever, headache, sore throat, general body weakness, cough, nausea, vomiting, diarrhoea, muscle pains, chest pain, and in severe cases; unexplainable bleeding from ears, eyes, nose, mouth, vagina, anus and other body orifices. It could also present as persistent bleeding from sites of intravenous cannulation.

The incubation period (time between an infection and appearance of symptoms of the disease) is 3 to 21 days. Early diagnosis and treatment increase the chances of survival.

Inappropriate use of personal protective equipment (PPE) such as gloves, masks and poor IPC practices, increase the risk of person to person transmission of Lassa fever. Other risk factors that can lead to health care worker infection include:

• Doctors, nurses and other health workers providing direct patient care without standard precautions.
• Hospital support staff cleaning or disinfecting contaminated surfaces, materials and supplies without adequate protective gear.
• Laboratory staff handling blood samples of patients without appropriate precautions.
•  Medical or hospital support staff preparing and/or handling dead bodies of Lassa fever patients without appropriate precautions.

To reduce the risk of Lassa fever, the Nigeria Centre for Disease Control (NCDC) offers the following advice to all health care workers:

• Practice standard precautions at all times while handling patients and body fluids i.e. always perform hand hygiene at the designated five moments, wear the correct PPE based on the procedure to be performed, irrespective of provisional diagnosis of the patient.
• Appropriately dispose and disinfect items used by Lassa fever patients such as syringes, thermometers, beddings, clothing, cups, plates, spoons, etc. Ensure injectables and sharp items are disposed safely.
• Clean the hospital environment regularly using appropriate materials and methods.
• Dispose of all healthcare waste in a safe manner.
• Maintain a high index of suspicion for Lassa fever i.e. be vigilant and look out for Lassa fever symptoms. Remember, not all fevers are due to malaria.
• Test all suspected cases of malaria using Rapid Diagnostic Test (RDT). When the RDT is negative, other causes of febrile illness including Lassa fever should be considered and cases investigated accordingly.

Any febrile illness that has not responded to 48 hours use of anti-malaria or antibiotics should raise an index of suspicion for Lassa fever!

Lassa Fever in Nigeria

At least 29 killed and 195 cases of the disease confirmed in the latest outbreak to hit the country, government says.

Nigerian authorities have announced increased emergency measures to contain the latest outbreak of Lassa fever in the West African country, following the death of 29 people this month from the viral disease.

“As at 24th of January 2020, 195 confirmed cases and 29 deaths had been reported in 11 states,” the Nigeria Centre for Disease Control (NCDC) said in a statement on Saturday.

A national emergency operations centre had been activated to coordinate the response “to the increasing number of Lassa fever cases” across the country.

The number of Lassa fever infections across West Africa every year is between 100,000 to 300,000, with about 5,000 deaths, according to the US Centres for Disease Control and Prevention (CDC).

Last year, the disease claimed more than 160 lives in Nigeria. 

In some areas of Sierra Leone and Liberia, 10 to 16 percent of the people admitted to hospitals annually have Lassa fever, according to the US CDC, demonstrating the serious impact the disease has on the region.

The number of cases usually climbs in January due to weather conditions during the dry season.