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Disease
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Incidence rate of acute febrile illness |
Number of acute febrile illness episodes per 1,000 person-years of follow-up in the symptomatic disease cohort, overall and stratified by country and site. An acute febrile illness case is defined as a self-reported fever of > 48 hours duration (lasting at least two consecutive nights) + 1 of the signs/symptoms- headache, abnormal bleeding (from mouth, nose, rectum, and/or vagina), chest pain, oedema of the neck/face, joint pain, conjunctival or sub-conjunctival haemorrhage, vomiting, jaundice, cough, spontaneous abortion, sore throat, buzzing in ears/acute deafness, abdominal pain, hypotension, and recent contact with a confirmed LF case. |
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Incidence rate of symptomatic confirmed LF |
Number of confirmed LF cases per 1,000 person-years of follow-up overall and stratified by country, site, age groups, gender, viral clade, and baseline serostatus. A confirmed LF case is someone fulfilling an acute febrile illness case definition and has a positive Lassa RT-PCR test result. |
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Clinical course of LF |
Percentage of confirmed LF cases classified with a disease stage 3 or 4 (see SAP) at different timepoints (admission, during admission and before discharge) and stratified by risk groups |
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Case fatality risk |
Percentage of confirmed LF cases dying within 30 days of diagnosis or attributable to LF disease as assessed by the treating clinician at any point past confirmation |
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Occurrence of SNHL |
Percentage of all confirmed LF cases with SNHL assessed by audiometry prior to discharge. SNHL is defined as hearing loss of at least 30dB in three sequential frequencies in the standard pure tone audiogram, where a physical examination has excluded conductive hearing loss. |
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Occurrence or delayed/persistent SNHL/other sequelae |
Percentage of all LF survivors with SNHL at 4 months after hospital discharge. Delayed SNHL is defined as audiometry consistent with SNHL at follow-up but not at hospitalisation. Persistent SNHL is defined as audiometry consistent with SNHL at hospitalisation and at follow-up. |
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Prevalence of symptomatic confirmed LF co-infected with malaria parasites |
The percentage of all confirmed LF cases among whom presence of malaria parasites assessed by antigen RDT is detected at the time of LF diagnosis |
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Risk factors for symptomatic confirmed LF |
Association between the incidence rate of symptomatic LF disease and prespecified characteristics of the study subjects, expressed as an incidence rate ratio |
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LF Severity |
Due to the absence of a well-established severity scoring system, a severity scoring system for use in clinical trials will be developed from clinical and laboratory information collected from confirmed LF cases. |
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Infection
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Incidence rate of LASV infection |
The number of individuals who change from seronegative (absence of Lassa-specific serum antibodies in either IgG or IgM-ELISA) to seropositive status (presence of Lassa-specific serum antibodies in either IgG or IgM-ELISA) per 1,000 person-years of follow-up in the infection cohort, overall and stratified by country, site, and age groups |
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Seroprevalence |
The percentage of subjects found to be seropositive (IgG+) out of the number of subjects tested for baseline seropositivity overall and stratified by country, site, and age group |
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Risk factors for LASV infection |
The association between the incidence rate of LASV infection and prespecified characteristics of the study participants or their households, expressed as an IRR |
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Risk factors for seropositivity: |
The ratio of the odds of being seropositive at baseline in prespecified risk groups to the odds in the study population without the prespecified risk, expressed as an odds ratio (OR) |
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Incidence of seroreversion |
The number of individuals who change from seropositive to seronegative per 1,000 person-years of follow-up in the infection cohort, overall and stratified by country, site, and age groups |
