Lassa Fever in Travelers from West Africa, 1969–2016

Abstract

Lassa virus is a rodentborne arenavirus responsible for human cases of Lassa fever, a viral hemorrhagic fever, in West Africa and in travelers arriving to non–Lassa-endemic countries from West Africa. We describe a retrospective review performed through literature search of clinical and epidemiologic characteristics of all imported Lassa fever cases worldwide during 1969–2016. Our findings demonstrate that approximately half of imported cases had distinctive clinical features (defined as fever and >1 of the following: pharyngitis, sore throat, tonsillitis, conjunctivitis, oropharyngeal ulcers, or proteinuria). Delays in clinical suspicion of this diagnosis were common. In addition, no secondary transmission of Lassa fever to contacts of patients with low-risk exposures occurred, and infection of high-risk contacts was rare. Future public health investigations of such cases should focus on timely recognition of distinctive clinical features, earlier treatment of patients, and targeted public health responses focused on high-risk contacts.

Public health response to two imported, epidemiologically related cases of Lassa fever in the Netherlands (ex Sierra Leone), November 2019

“…Lassa virus causes an estimated 300,000 infections per year worldwide with, in 80% of the cases, no or very mild symptoms and, in 20% of cases, severe disease (haemorrhages and multi-organ failure) [6,9]. The case fatality is 15-20% in hospitalised cases [10]. There is no evidence of human-to-human transmission from asymptomatic carriers, but well-designed studies to address this question are lacking [9,11].…”

“…Awareness of the local risks and implementation of standard precautions to reduce the risk of transmission of blood-borne pathogens are essential to prevent nosocomial transmission [8,13]. As LASV infection is initially difficult to diagnose clinically, rapid and accurate differential laboratory diagnostics are crucial to initiate appropriate supporting care and to set up measures to prevent human-to-human transmission [9,10]. PEP with ribavirin was not advised for contacts in the Netherlands because the evidence on effectiveness is inconclusive while potential side effects can be severe [14,15].…”

“…The psychosocial burden of the death of the Dutch healthcare worker and of the measures on the patients, contacts and their families was reported as considerable. Protocols are required that adequately balance the necessary containment measures and the psychosocial burden on patients, contacts and care providers [10]. The response teams in the involved countries in the EU and European Economic Area appeared to use different Lassa fever protocols regarding PEP and testing of asymptomatic contacts (personal communication, UK EWRS team, 23 November 2019).…”

Improving Cross-Border Preparedness and Response: Lessons Learned from 3 Lassa Fever Outbreaks Across Benin, Nigeria, and Togo, 2017-2019

“…1 This human movement inherently increases the risk of the international spread of disease, as evidenced by the West Africa Ebola epidemic of 2014-2016 and repeated international cholera and Lassa fever outbreaks. [2][3][4] Limiting the geographic spread of disease within a country requires comprehensive public health practice, including sensitive disease surveillance systems, timely and thorough outbreak response measures, and adequate staffing and infrastructure, with good communication across all participating agencies. Preparing for and responding to the international spread of disease has the added complexity of requiring information sharing and coordination between 2 or more unrelated public health systems, each with unique methods, staffing, and infrastructure.…”

Detection of Antibody and Antigen for Lassa Virus Nucleoprotein in Monkeys from Southern Nigeria

“…Lassa fever outbreaks are still a major public health problem in many communities of West Africa despite five decades of its discovery and various regional and international efforts at controlling the disease [1]. Nigeria recorded the largest Lassa fever outbreak in 2018 with 633 confirmed cases and 171 human deaths despite the huge human, material and financial resources deployed to control the outbreaks [2].…”