Definition
Lassa fever is an infectious disease caused by a viral agent belonging to the Arenavirus family. This disease is widespread especially in rural areas of West Africa; in particular, Lassa fever is endemic in Nigeria, Liberia, Sierra Leone and Guinea; in these countries, in fact, the natural reservoir of the viral agent is widespread, represented by Mastomys natalensis, a rat that commonly infests domestic environments.
Man becomes infected through direct contact with the infected host or through ingestion of food contaminated by saliva and rodent urine. Human-to-human transmission can also occur through contact with urine, faeces, saliva, vomiting, blood, secretions and other biological fluids of subjects suffering from Lassa fever. The infection can also occur through contaminated medical material (eg needles and syringes).
Most common symptoms and signs *
- Miscarriage
- Alopecia
- Anorexia
- Asthenia
- Increased transaminases
- bradycardia
- Chills
- Retrosternal burning
- Cachexia
- Conjunctivitis
- Convulsions
- Abdominal cramps
- Diarrhea
- Dysphagia
- Dyspnoea
- Abdominal pain
- Chest pain
- Pain in the upper part of the abdomen
- Articolar pains
- Muscle pains
- Bruising
- Edema
- Hepatitis
- Hepatomegaly
- Rash
- Ease of bleeding and bruising
- Pharyngitis
- Temperature
- I made clear
- Eyelid swelling
- Portal hypertension
- Hearing loss
- Hypotension
- Hypovolemia
- Jaundice
- Swollen lymph nodes
- Sore throat
- Backache
- Headache
- Nausea
- petechiae
- Proteinuria
- itch
- rales
- Nosebleeds
- Bleeding gums
- Drowsiness
- Cough
- Tremors
- Dark urine
- Pericardial effusion
- Pleural effusion
- Dizziness
- He retched
Further indications
Lassa fever can involve many organs and systems. After an incubation period of 5-16 days, the disease manifests itself with fever (gradually progressive), headache, muscle pain, weakness and gastro-intestinal symptoms, such as nausea, diarrhea, dysphagia and epigastric pain. In the following 4-5 days, sore throats with tonsillar exudate, dry cough, chest pain and vomiting occur. In some patients, cutaneous and mucosal bleeding, hearing loss, maculo-papular eruptions and vertigo may also occur.
In patients who recover, progressive resolution of symptoms occurs; severely affected patients often develop edema of the face and neck, conjunctivitis, hypotension, bradycardia, pleural effusions, pulmonary edema, proteinuria and peripheral vasoconstriction. If contracted during pregnancy, Lassa fever can cause fetal loss.
In advanced stages, the disease can get complicated with hepatitis and pericarditis. Infection can be fatal due to hypovolemic shock or acute liver failure.
The diagnosis is based on PCR and serological tests: the detection of the viral genome and IgM antibodies against the etiologic agent of Lassa fever are investigations that confirm the exposure to the virus responsible for the disease. Support tests include liver function tests, urinalysis, complete blood count and chest radiographs.
Lassa fever therapy involves the use of intravenous ribavirin; this drug is able to reduce mortality, if administered early (within the first 6 days). Furthermore, supportive therapies are provided, including the correction of hydro-electrolytic imbalances.
At the moment, there is no effective vaccine to protect against Lassa fever. For prevention, contact with the infection reservoirs should be avoided by adopting appropriate environmental hygiene measures.
