Lassa Fever – facts & information from World Health Organisation

What is Lassa Fever?
What is Lasser Fever?

Lassa Fever Key facts

Lassa fever is an acute viral haemorrhagic illness of 2-21 days duration that occurs in West Africa. The Lassa virus is transmitted to humans via contact with food or household items contaminated with rodent urine or faeces.
Person-to-person infections and laboratory transmission can also occur, particularly in hospitals lacking adequate infection prevent and control measures.
Lassa fever is known to be endemic in Benin, Ghana, Guinea, Liberia, Mali, Sierra Leone, and Nigeria, but probably exists in other West African countries as well. The overall case-fatality rate is 1%. Observed case-fatality rate among patients hospitalized with severe cases of Lassa fever is 15%.
Early supportive care with rehydration and symptomatic treatment improves survival.


Though first described in the 1950s, the virus causing Lassa disease was not identified until 1969. The virus is a single-stranded RNA virus belonging to the virus family Arenaviridae.

About 80% of people who become infected with Lassa virus have no symptoms. 1 in 5 infections result in severe disease, where the virus affects several organs such as the liver, spleen and kidneys.

Lassa fever is a zoonotic disease, meaning that humans become infected from contact with infected animals. The animal reservoir, or host, of Lassa virus is a rodent of the genus Mastomys, commonly known as the “multimammate rat.” Mastomys rats infected with Lassa virus do not become ill, but they can shed the virus in their urine and faeces.

Because the clinical course of the disease is so variable, detection of the disease in affected patients has been difficult. When presence of the disease is confirmed in a community, however, prompt isolation of affected patients, good infection prevention and control practices, and rigorous contact tracing can stop outbreaks.

Lassa fever is known to be endemic in Benin (where it was diagnosed for the first time in November 2014), Ghana (diagnosed for the first time in October 2011), Guinea, Liberia, Mali (diagnosed for the first time in February 2009), Sierra Leone, and Nigeria, but probably exists in other West African countries as well.
Symptoms of Lassa fever

The incubation period of Lassa fever ranges from 6–21 days. The onset of the disease, when it is symptomatic, is usually gradual, starting with fever, general weakness, and malaise. After a few days, headache, sore throat, muscle pain, chest pain, nausea, vomiting, diarrhoea, cough, and abdominal pain may follow. In severe cases facial swelling, fluid in the lung cavity, bleeding from the mouth, nose, vagina or gastrointestinal tract and low blood pressure may develop.

Symptoms of Lasser fever
Symptoms of Lasser fever

Protein may be noted in the urine. Shock, seizures, tremor, disorientation, and coma may be seen in the later stages. Deafness occurs in 25% of patients who survive the disease. In half of these cases, hearing returns partially after 1–3 months. Transient hair loss and gait disturbance may occur during recovery.

Death usually occurs within 14 days of onset in fatal cases. The disease is especially severe late in pregnancy, with maternal death and/or fetal loss occurring in more than 80% of cases during the third trimester.

Humans usually become infected with Lassa virus from exposure to urine or faeces of infected Mastomys rats. Lassa virus may also be spread between humans through direct contact with the blood, urine, faeces, or other bodily secretions of a person infected with Lassa fever. There is no epidemiological evidence supporting airborne spread between humans. Person-to-person transmission occurs in both community and health-care settings, where the virus may be spread by contaminated medical equipment, such as re-used needles. Sexual transmission of Lassa virus has been reported.

Lassa fever occurs in all age groups and both sexes. Persons at greatest risk are those living in rural areas where Mastomys are usually found, especially in communities with poor sanitation or crowded living conditions. Health workers are at risk if caring for Lassa fever patients in the absence of proper barrier nursing and infection prevention and control practices.

Because the symptoms of Lassa fever are so varied and non-specific, clinical diagnosis is often difficult, especially early in the course of the disease. Lassa fever is difficult to distinguish from other viral haemorrhagic fevers such as Ebola virus disease as well as other diseases that cause fever, including malaria, shigellosis, typhoid fever and yellow fever.

Definitive diagnosis requires testing that is available only in reference laboratories. Laboratory specimens may be hazardous and must be handled with extreme care. Lassa virus infections can only be diagnosed definitively in the laboratory using the following tests:

reverse transcriptase polymerase chain reaction (RT-PCR) assay
antibody enzyme-linked immunosorbent assay (ELISA)
antigen detection tests
virus isolation by cell culture.

Treatment and prophylaxis

The antiviral drug ribavirin seems to be an effective treatment for Lassa fever if given early on in the course of clinical illness. There is no evidence to support the role of ribavirin as post-exposure prophylactic treatment for Lassa fever.

There is currently no vaccine that protects against Lassa fever.
Prevention and control

Prevention of Lassa fever relies on promoting good “community hygiene” to discourage rodents from entering homes. Effective measures include storing grain and other foodstuffs in rodent-proof containers, disposing of garbage far from the home, maintaining clean households and keeping cats. Because Mastomys are so abundant in endemic areas, it is not possible to completely eliminate them from the environment. Family members should always be careful to avoid contact with blood and body fluids while caring for sick persons.

In health-care settings, staff should always apply standard infection prevention and control precautions when caring for patients, regardless of their presumed diagnosis. These include basic hand hygiene, respiratory hygiene, use of personal protective equipment (to block splashes or other contact with infected materials), safe injection practices and safe burial practices.

Health-care workers caring for patients with suspected or confirmed Lassa fever should apply extra infection control measures to prevent contact with the patient’s blood and body fluids and contaminated surfaces or materials such as clothing and bedding. When in close contact (within 1 metre) of patients with Lassa fever, health-care workers should wear face protection (a face shield or a medical mask and goggles), a clean, non-sterile long-sleeved gown, and gloves (sterile gloves for some procedures).

Laboratory workers are also at risk. Samples taken from humans and animals for investigation of Lassa virus infection should be handled by trained staff and processed in suitably equipped laboratories under maximum biological containment conditions.

On rare occasions, travellers from areas where Lassa fever is endemic export the disease to other countries. Although malaria, typhoid fever, and many other tropical infections are much more common, the diagnosis of Lassa fever should be considered in febrile patients returning from West Africa, especially if they have had exposures in rural areas or hospitals in countries where Lassa fever is known to be endemic. Health-care workers seeing a patient suspected to have Lassa fever should immediately contact local and national experts for advice and to arrange for laboratory testing.

Content source: World Health Organization

Notes from the field – A west Nigerian doctor practising medicine in northern Nigeria

Notes from the field of medical practice in northern Nigeria
Notes from the field of medical practice in northern Nigeria

The practice of medicine is guided by ethics and principles. However, culture, religion and beliefs often influence the practice of medicine in most regions of the country, including northern Nigeria.

It is pertinent to note that medical practice in the north is an interesting one based on its peculiarities that stem from many factors among which are the aforementioned.

It is worthy of mention that majority of northerners are muslims, with unique culture, belief and tradition.The north is also a highly populated region of the country.

The maternity wing of any hospital can attest to the population strength of any northern state. There is a good number of quite young primigravidae and of course, many great grand, multiparous women.
It’s far from anything surprising to come across women with their 10th, 13th or even 18th pregnancy and looking like they never had one. I must admit that northern women are exceptionally strong in terms of pregnancy and childbirth. The implications of this as a healthcare provider, in the obstetrics and gynecology department is that you must be ready for a huge, yet interesting task. It’s an avenue to see and gather experience from various obstetrics cases, ranging from normal labour, missed abortions to ruptured uterus.

The outpatient department is indeed another people-laden section of any hospital, as the population could be so large that a doctor may have over 50 to 70 patients to attend to within a shift.

One of the major reasons why the hospitals enjoy large patronage is because of the subsidization of healthcare by the governments in nothern Nigeria. In Kano, (northwest Nigeria), for example, caesarian sections in general hospitals are done free of charge.

The healthcare provider encounters various cases ranging from the ‘common’ malaria to some cases only seen in medical text books while undergoing training in the medical school. It’s often said that you really cannot boast of having experience in the medical field if you have never practiced in the north.

A very important peculiarity worthy of mention is the religious and cultural belief associated with consulting female patients. It is a common practice that only female medical personnel are permitted to attend to female patients. It is prohibited for a man, even a medical doctor to have any close association with a female, except in cases of emergencies where female healthcare workers are not available. This is sometimes a common cause of frictions and restrictions when attending to female patients in need of medical attention. This also accounts for the high demand for female obstetricians and gynaecologists in northern Nigeria.

The most frequently encountered challenge of medical practitioners in the north is late presentation of patients to the health facilities. This increases the number of complicated and sometimes irredeemable cases that the health professional has to attend to. There is usually an initial reluctance to attend the hospital, despite the fact that treatment is often free. Many locals would rather try out all sorts of herbs and patronise tradomedical healers before coming to a health centre.

Some of these practices include, traditional bone setting in cases of fractures, making incisions on the chest wall to let out blood in a case of chest pain, making incisions and cutting open swellings on parts of the body.

Another common practice is that which predisposes women to heart failure after childbirth. It is the habit of hot water bath and potash- in pap meal. It is indeed a common cause of peripartal cardiomyopathy amongst northern women and often complicated with heart failure.

All of these practices increase the incidence of diseases. It also makes managing other illnesses extremely difficult, considering the fact that there are a lot of such incidents and resources allocated to resolving health issues are limited.

All these said, it’s quite an interesting experience practicing in the north. It simply demands understanding the peculiarities and challenges, and finding a way aroud them.

Allah ya taimaka kuma ya bada zaman lapia.

Dr. Abdulazeez Abiola Ismail
Kano State, Nigeria