Pediatricians need to be aware of Lassa virus risk factors and treatment standards, as the virus may be an unrecognized source of infection among children newly arrived in the United States from endemic areas.

“We ‎want physicians to be aware of Lassa fever, which can be severe, even though it is rare in the US,” Dr. Eric J. Dziuban from the Centers for Disease Control and Prevention (CDC), in Atlanta, Georgia told Reuters Health. “Early recognition can improve the care for the patient and reduce the risk of transmission to others.”

Dr. Dziuban and colleagues review Lassa fever’s virology and epidemiology, clinical manifestations and prognosis, diagnosis and treatment, and contact precautions in a viewpoint article online in JAMA Pediatrics.

Lassa fever, caused by an RNA virus, is hyperendemic in Guinea, Liberia, Nigeria, and Sierra Leone, where outbreaks occur primarily in the dry season (November to April). Children under 10 years of age are most vulnerable.

The virus is shed in the urine and feces of the multimammate rat reservoir and is transmitted from rats to humans through contact with these materials. It spreads from human to human by direct contact with body fluids from symptomatically infected individuals or corpses, and nosocomial outbreaks have been reported.

Disease manifestations in children range from asymptomatic to viral hemorrhagic fever (VHF) leading to death. The incubation period is 7 to 21 days, and most signs and symptoms are nonspecific: fever, general malaise, cough, sore throat, retrosternal pain and myalgia.

Detection modalities include enzyme-linked immunosorbent serologic assays and reverse transcriptase-polymerase chain reaction. Special handling conditions are required because specimens from patients with Lassa fever can be infectious. CDC provides testing and confirmation for Lassa virus in the U.S.

Aggressive management of hypovolemia, supportive treatment for fever, and management of electrolyte imbalances are important components of therapy. Ribavirin has been shown to reduce mortality in adults if given in the first six days after onset; although there are no studies showing its effectiveness in children, ribavirin treatment should begin once a diagnosis of Lassa fever is confirmed.

“A pediatrician should first consider if the patient’s illness is consistent with Lassa and whether the patient has any risk factors, such as recent travel (within the past three weeks) to a country with Lassa, and whether they stayed in rural areas or had contact with sick people,” Dr. Dziuban said. “It is important to ask questions about when the patient traveled, where they traveled to, and when they first started feeling sick.”

“The doctor should also consider more common causes of illness in patients coming to the U.S. from Africa, especially malaria,” he said. “If the patient’s illness and recent activities could fit Lassa infection, the doctor should wear protective gear while caring for the patient, and the local or state health department should be contacted about testing and treatment.”

Early diagnosis is a key. Once the diagnosis is confirmed, treatment with favipiravir and ribavirin seem (to be the) best options currently available. This treatment is still considered as under IND regulation because neither ribavirin nor favipiravir is approved for Lassa fever treatment.

“Development of an effective preventive vaccine with 100% coverage for all genetic Lassa virus phylogenetic clades circulated in West Africa is the only way to control this infection,” he said. “The recently created Coalition for Epidemic Innovation Preparedness (CEPI) has an ambitious plan to develop several vaccine candidates for Lassa fever during the coming 5 years.”