WHO, 2017. Lassa fever. World Health Organization (WHO). Accessed 3 November 2020.
" }, "editorialNote": { "en": [ "source:UNDRR HIPS" ] }, "scopeNote": { "en": [ "Although first described in the 1950s, the virus causing Lassa disease was not identified until 1969. The virus is a singlestranded RNA virus belonging to the virus family Arenaviridae. 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 can shed the virus in their urine and faeces (WHO, 2017). People at greatest risk are those living in rural areas where Mastomys are usually found, especially in communities with poor sanitation or crowded living conditions. Lassa fever occurs in all age groups and both sexes. About 80% of people who become infected with Lassa virus have no symptoms. One in five infections results in severe disease, where the virus affects several organs such as the liver, spleen and kidneys. Because the clinical course of the disease is so variable, detection of the disease in affected patients has been difficult. When the disease is confirmed to be present in a community, however, prompt isolation of affected patients, good infection prevention and control practices, and rigorous contact tracing can stop outbreaks (WHO, 2017). The incubation period of Lassa fever ranges from 6 to 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. Shock, seizures, tremor, disorientation, and coma may be seen in the later stages. Death usually occurs within 14 days of onset in fatal cases. Deafness occurs in 25% of patients who survive the disease. In half of these cases, hearing returns partially after one to three months. Transient hair loss and gait disturbance may occur during recovery. The disease is especially severe late in pregnancy, with maternal death and/or foetal loss occurring in more than 80% of cases during the third trimester (WHO, 2017). Transmission is primarily from direct and indirect contact with the urine or faeces of infected Mastomys rats, usually from contaminated surfaces, food and water. 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 (WHO, 2017). Lassa fever is difficult to diagnose because the symptoms are non-specific. Definitive diagnosis requires viral and serological testing available only in reference laboratories. Isolation of the virus is usually done from blood, urine or throat washings (WHO, 2017). The Centers for Disease Control and Prevention has published information on case definitions and classification for viral haemorrhagic fevers (CDC, 2011)." ] }, "inScheme": [ { "id": "http://connectivity-hub.com/terms/", "title": { "en": "Climate Connectivity Taxonomy" } } ], "inSchemeAll": [ { "id": "http://connectivity-hub.com/terms/" } ], "topConceptOf": [ { "id": "http://connectivity-hub.com/terms/", "title": { "en": "Climate Connectivity Taxonomy" } } ], "@context": { "@version": 1.1, "id": "@id", "type": "@type", "@vocab": "http://www.w3.org/2004/02/skos/core#", "xsd": "http://www.w3.org/2001/XMLSchema#", "dct": "http://purl.org/dc/terms/", "dc": "http://purl.org/dc/elements/1.1/", "schema": "https://schema.org/", "vann": "http://purl.org/vocab/vann/", "ldp": "http://www.w3.org/ns/ldp#", "owl": "http://www.w3.org/2002/07/owl#", "title": { "@id": "dct:title", "@container": "@language" }, "dc:title": { "@id": "dc:title", "@container": "@language" }, "dc:description": { "@id": "dc:description", "@container": "@language" }, "description": { "@id": "dct:description", "@container": "@language" }, "license": { "@id": "dct:license", "@container": "@language" }, "issued": { "@id": "dct:issued", "@type": "xsd:date" }, "created": { "@id": "dct:created", "@type": "xsd:date" }, "modified": { "@id": "dct:modified", "@type": "xsd:date" }, "creator": "dct:creator", "publisher": "dct:publisher", "preferredNamespacePrefix": "vann:preferredNamespacePrefix", "preferredNamespaceUri": "vann:preferredNamespaceUri", "isBasedOn": "schema:isBasedOn", "source": "dct:source", "prefLabel": { "@container": "@language" }, "altLabel": { "@container": [ "@language", "@set" ] }, "hiddenLabel": { "@container": [ "@language", "@set" ] }, "definition": { "@container": "@language" }, "note": { "@container": [ "@language", "@set" ] }, "changeNote": { "@container": [ "@language", "@set" ] }, "editorialNote": { "@container": [ "@language", "@set" ] }, "historyNote": { "@container": [ "@language", "@set" ] }, "scopeNote": { "@container": [ "@language", "@set" ] }, "notation": { "@container": "@set" }, "example": { "@container": "@language" }, "narrower": { "@container": "@set" }, "related": { "@container": "@set" }, "relatedMatch": { "@container": "@set" }, "narrowerTransitive": { "@container": "@set" }, "broaderTransitive": { "@container": "@set" }, "broadMatch": { "@container": "@set" }, "narrowMatch": { "@container": "@set" }, "closeMatch": { "@container": "@set" }, "exactMatch": { "@container": "@set" }, "hasTopConcept": { "@container": "@set" }, "inScheme": { "@container": "@set" }, "topConceptOf": { "@container": "@set" }, "deprecated": { "@id": "owl:deprecated", "@type": "xsd:boolean" }, "isReplacedBy": { "@id": "dct:isReplacedBy", "@container": "@set" } } }