Can imported cases of Lassa fever highlight diagnostic challenges and strengthen public health preparedness in South Africa?
Viral haemorrhagic fevers (VHFs) remain a significant public health concern due to their potential to cause severe disease and high mortality. In non-endemic countries, recognition can be challenging because early symptoms are often non-specific and resemble more common febrile illnesses, which may delay diagnosis and response.
Lassa fever (LF) is an acute VHF caused by the Lassa virus, a member of the Arenaviridae family, and is endemic in several West African countries including Benin, Ghana, Guinea, Liberia, Mali, Nigeria, and Sierra Leone. Transmission to humans typically occurs through exposure to the urine, faeces, or saliva of infected Mastomys natalensis rodents, while human-to-human transmission through contact with infected bodily fluids can also occur. LF is the most frequently reported VHF among travellers returning from endemic regions.
This report describes two imported cases of LF diagnosed in South Africa in 2007 and 2022, outlining the clinical presentations, diagnostic processes, and public health responses associated with each case. By examining these events, the report highlights key diagnostic challenges and lessons learned to strengthen preparedness, clinical awareness, and response to imported VHFs in non-endemic settings.
Materials and methods
A retrospective document review was conducted using data collected during routine investigations of VHF in SA.
The National Institute for Communicable Diseases (NICD), a division of the National Health Laboratory Service, serves as the national reference laboratory for VHF in SA. The NICD curates a database for confirmed VHF cases, which was compiled through data collection from test request and submission forms, case investigation forms, field investigation reports by provincial Department of Health (DoH) Communicable Disease Clusters, emails and electronic messaging from referring hospitals, and the NICD hotline phone calls received for medical advice, as available for each case.
Confirmed LF cases were defined as cases for which clinical samples tested positive by reverse transcription Polymerase Chain Reaction (RT-PCR)6 and/or anti-LASV IgM positive and/or a fourfold increase in anti-LASV IgG in serially collected blood samples.
Case descriptions
Case 1
A 46-year-old male from Nigeria was evacuated to South Africa in February 2007 after developing fever, gastrointestinal symptoms, and later neurological and haemorrhagic manifestations with renal failure. Lassa virus infection was confirmed by RT-PCR and serology.
Case 2
A 60-year-old male with recent travel in Nigeria was admitted in May 2022 with fever, vomiting, and renal impairment. Initial focus on common febrile illnesses delayed diagnosis. LF was confirmed posthumously by RT-PCR.
Discussion
Both cases highlight diagnostic challenges in non-endemic settings, where early symptoms overlap with other infections. Management and infection control, including isolation and PPE, limited nosocomial transmission.
The cases underscore the importance of travel history, rapid diagnostics, and clinician awareness. They also illustrate the epidemiological risk of LF importation via global travel and the need for integrated surveillance and preparedness in non-endemic countries.
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