Lassa fever is an acute viral illness caused by the Lassa virus; it was first discovered in 1969 in the town of Lassa, in Borno State, Nigeria, when two missionary nurses died. The virus, a member of the virus family Arenaviridae, is a single stranded RNA virus and is zoonotic, or animal borne.
The endemic disease which has in the past days killed more than 40 people in Nigeria has a broadened geographic ambit in West Africa as it is recognized in Guinea, Liberia and Sierra Leone, due to the nature of the rodent species, inhabiting these regions.
While divulging the death toll, It should be noted that Nigeria’s Health Minister Isaac Adewole on Friday Januray 8, 2016 said that seven of the affected states are in the north — Bauchi, Nasarawa, Niger, Taraba, Kano, Plateau and Gombe — while the remaining three are in the south — Rivers, Edo and Oyo.
The host of Lassa virus is a rodent known as the “multimammate rat” of the genus Mastomys. It is not certain which species of Mastomys are associated with Lassa; however, at least two species carry the virus in Sierra Leone. Mastomys ‘generally’ readily colonize human homes.
How Humans Contact Lassa Fever
Due to the fact that Mastomys rodents often live in and around homes and scavenge on human food remains or poorly stored food, transmission of this sort is common.
- The Mastomys rodents shed the virus in urine and droppings. Therefore, the virus can be transmitted through direct contact with these materials, through touching objects or eating food contaminated with these materials, or through cuts or sores.
- Contact with the virus also may occur when a person inhales tiny particles in the air contaminated with rodent excretions. This is called aerosol or airborne transmission.
- Since Mastomys rodents are sometimes consumed as a food source, infection may occur via direct contact when they are caught and prepared for food.
- Lassa fever may also spread through person to person contact. This type of transmission occurs when a person comes into contact with virus in the blood, tissue, secretions, or excretions of an individual infected with the Lassa virus.
- Person to person transmission is common in both village and health care settings, where, along with the above mentioned modes of transmission, the virus also may be spread in contaminated medical equipment, such as re-used needles.
Note: The virus cannot be spread through casual contact (including skin to skin contact without exchange of body fluids).
Signs And Symptoms Of Lassa Fever
As soon as the virus reaches an incubation period of six to 21 days, an acute illness with multiorgan involvement develops. Victims experience nonspecific symptoms like fever, facial swelling, and muscle fatigue, as well as conjunctivitis and mucosal bleeding.
The other symptoms arising from the affected organs are:
Gastrointestinal tract, Nausea, Vomiting (bloody), Diarrhea (bloody), Stomach ache, Constipation, Dysphagia (difficulty swallowing), Hepatitis, Cardiovascular system, Pericarditis, Hypertension, Hypotension, Tachycardia (abnormally high heart rate), Respiratory tract, Cough, Chest pain, Dyspnoea, Pharyngitis, Pleuritis, Nervous system, Encephalitis, Meningitis, Unilateral or bilateral hearing deficit and Seizures.
The virus is excreted in urine for 3-9 weeks and in semen for three months.
Prevention For Lassa Fever
Control of the Mastomys rodent population is impractical, so measures are limited to keeping rodents out of homes and food supplies, as well as maintaining effective personal hygiene. Gloves, masks, laboratory coats, and goggles are advised while in contact with an infected person.
Where the wide spread of Mastomys is irrepressible, putting food away in rodent proof containers and keeping the home clean help to discourage rodents from entering homes. Using these rodents as a food source is not recommended. Trapping in and around homes can help reduce rodent populations.
Treatment For Lassa fever
All persons suspected of Lassa fever infection should be admitted to isolation facilities and their body fluids and excreta properly disposed of.
Ribavirin, an antiviral drug, has been used with success in Lassa fever patients. It has been shown to be most effective when given early in the course of the illness. Patients should also receive supportive care consisting of maintenance of appropriate fluid and electrolyte balance, oxygenation and blood pressure, as well as treatment of any other complicating infections.