Lassa fever natural history, complications and prognosis
|
Lassa fever Microchapters |
|
Diagnosis |
|---|
|
Treatment |
|
Case Studies |
|
Lassa fever natural history, complications and prognosis On the Web |
|
American Roentgen Ray Society Images of Lassa fever natural history, complications and prognosis |
|
FDA on Lassa fever natural history, complications and prognosis |
|
CDC on Lassa fever natural history, complications and prognosis |
|
Lassa fever natural history, complications and prognosis in the news |
|
Blogs on Lassa fever natural history, complications and prognosis |
|
Risk calculators and risk factors for Lassa fever natural history, complications and prognosis |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [2]; Associate Editor(s)-in-Chief: Ammu Susheela, M.D. [3]
Synonyms and keywords: Lassa hemorrhagic fever; LHF
Overview
Signs and symptoms of Lassa fever typically occur 1-3 weeks after the patient comes into contact with the virus. The most common complication of Lassa fever is deafness. Various degrees of deafness occur in approximately one-third of cases, and in many cases hearing loss is permanent. Spontaneous abortion is another serious complication. Approximately 15%-20% of patients hospitalized for Lassa fever die from the illness. However, overall only about 1% of infections with Lassa virus result in death. The death rates are particularly high for women (greater than 80%) in the third trimester of pregnancy, and for fetuses, about 95% of which die in the uterus of infected pregnant mothers.
Natural History
Incubation Period
- Infected patients remain asymptomatic for 1 to 3 weeks following exposure.
Development of Clinical Manifestations
- The majority of patients experience no or mild symptoms. Only a minority (approximately 15-20%) of patients experience multiorgan dysfunction, and typically 5-15% of infected patients die of Lassa fever.
- Patients typically first develop fever and other non-specific symptoms of viral illnesses, such as muscle aches, conjunctival injection, headache, sore throat, nausea, and vomiting.
abdominal pain, weakness, cough, headache, exudative pharyngitis, anemia, low blood pressure, and diarrhea. Because its symptoms are similar to other febrile illness found in Africa, Lassa virus is hard to diagnose.
- If left untreated, the majority of patients self-resolve without any intervention.
- In a minority of cases, patients may develop worsening abdominal/chest pain, temporary/permanent deafness, facial edema, mucosal bleeding, pulmonary edema, pleural/pericardial effusions or ascites, multi-organ failure, and shock.
- Prolonged and worsening symptoms are usually associated with worsening prognosis, typically resulting in convulsions, encephalitis, seizures, coma and finally death.
- Clinical stages of Lassa fever (adapted from McCarthy)[1]
| Stage | Symptoms | Days |
| Stage 1 | High fever of 39°C with peaks of 40°C-41°C, malaise, weakness | Day1 -day 3 |
| Stage 2 | Headache, backache, chest pain, exudative sore throat with white patches, abdominal pain, diarrhea, nausea, vomiting, low blood pressure, anemia, proteinuria, conjunctivitis | Day4 -day 7 |
| Stage 3 | Mucosal bleeding, internal bleeding, facial edema, confusion, disorientation and convulsion | >7 days |
| Stage 4 | Coma, death | >14 days |
Complications
- Complications of Lassa fever include the following.
Sensorineural Deafness
- The most common complication of Lassa fever is deafness.
- Occurs in 1/3rd of the cases.
- Various degrees of deafness occur in approximately one-third of infections, and in many cases hearing loss is permanent.
- As far as is known, severity of the disease does not affect this complication: deafness may develop in mild as well as in severe cases.
- It could be unilateral or bilateral.
Lassa Fever in Pregnancy
- Increased mortality in 3rd trimester of more than 30% to the mother.
- Increased viremia in pregnant woman.
- Evacuation of the uterus improves mother's chance of survival.
- Placental infection of the fetus.
- Spontaneous abortion is a serious complication of infection with an estimated 95% mortality in fetuses of infected pregnant mothers.
- Increased fetal and neonatal mortality of more than 85%.
Lassa Fever in Children
Swollen Baby Syndrome
- Edema.
- Abdominal distention.
- Bleeding.
- Poor prognosis.
Prognosis
- Approximately 15%-20% of patients hospitalized for Lassa fever die from the illness. However, only 1% of all Lassa virus infections result in death. Prognosis of Lassa fever is poor if its associated with following features[2].
- Increased viremia.
- Serum AST level > 150 IU/L
- Bleeding.
- Encephalitis.
- Edema
- Third trimester of pregnancy.
References
- ↑ McCarthy M (2002). "USA moves quickly to push biodefence research". Lancet. 360 (9335): 732. doi:10.1016/S0140-6736(02)09938-5. PMID 12296302.
- ↑ "The Centers for Disease Control and Prevention".