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A review of the recent advances on Lassa fever with special reference to molecular epidemiology and progress in vaccine development

1Medugu, N., *1Adegboro, B., 2Babazhitsu, M. S., 3Kadiri, M., and 4Abanida, E. A.

1Departments of Medical Microbiology and Immunology, Nile University of Nigeria, Abuja, Nigeria

2Department of Medical Microbiology and Parasitology, Faculty of Basic Clinical Sciences, College of Health Sciences, Usmanu Danfodiyo University, Sokoto, Nigeria

3Department of Medical Microbiology and Parasitology, University of Ilorin Teaching Hospital, Ilorin, Nigeria 4Epidemiology Unit, World Health Organization, Harare, Zimbabwe                                             

*Correspondence to: boazadegboro@gmail.com

Abstract:

Lassa fever, a viral hemorrhagic fever caused by the Lassa virus (LASV), is endemic in West Africa and is associated with high morbidity and mortality. At least three of the four proposed seven lineages of LASV are found in Nigeria, where the multimammate rat, Mastomys natalensis, serves as the primary reservoir. Endemic countries report approximately 200,000 infections and 5,000 deaths annually, with Nigeria experiencing thousands of infections and hundreds of deaths including healthcare workers. The aim of this review is to provide scientific information for better understanding of the evolutionary biology, molecular epidemiology, pathogenesis, diagnosis, and prevention of Lassa fever in Nigeria and other endemic regions worldwide, which can lead to improved control efforts and reduce morbidity and mortality from recurrent epidemics. To achieve this aim, observational studies such as case series, cross-sectional and cohort studies published between December 2017 and September 2022 were searched for on various online databases including Google Scholar, Africa Journals Online (AJOL), Research Gates, PubMed, PMIC, NCDC, and WHO websites. Although the origin and evolutionary history, and the transmission dynamics of Lassa virus have been revealed through recent molecular epidemiological studies, the factors that drive the evolution of the virus remain unclear. Genetic changes in the viral genome may have enabled the virus to adapt to humans. Diagnosis of Lassa fever has also advanced from basic serological tests to more sophisticated methods such as quantitative real time polymerase chain reaction (qRT-PCR) and sequencing, which are particularly useful for identifying outbreak strains. Several vaccines, including recombinant vesicular stomatitis virus (rVSV), virus-like particle (VLP), and DNA-based vaccines, have shown promise in animal models and some have progressed to phase 2 clinical trials. Preventing and controlling Lassa fever is critical to safeguard the health and well-being of affected communities. Effective measures such as rodent control, improved sanitation, and early detection and isolation of infected individuals are essential for reducing transmission. Ongoing research into the genetic and ecological factors that drive the evolution of Lassa virus is necessary to reduce the impacts of Lassa fever. Continue reading “A review of the recent advances on Lassa fever with special reference to molecular epidemiology and progress in vaccine development”

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Knowledge, attitude and practice of infection prevention and control among healthcare workers: one year after an outbreak of nosocomial Lassa fever in a tertiary hospital in southeast Nigeria

*1,2Adeke, A. S., 3Onoh, R. C., 1,2Umeokonkwo, C. D., 1Azuogu, B. N., and 4Ogah, E. O.

1Department of Community Medicine, Alex Ekwueme Federal University Teaching Hospital, Abakaliki, Ebonyi State, Nigeria
2Nigeria Field Epidemiology and Laboratory Training Program, Abuja, Nigeria
3Department of Obstetrics and Gynaecology, Alex Ekwueme Federal University Teaching Hospital, Abakaliki, Ebonyi State, Nigeria
4Department of Pediatrics, Alex Ekwueme Federal University Teaching Hospital, Abakaliki, Ebonyi State, Nigeria
*Correspondence to: azukaadeke@gmail.com; +2348035285133

Abstract:
Background: With the rise in cases of Lassa fever in recent times in West Africa, the healthcare setting continues to pose significant risk especially among healthcare workers (HCWs) for diseases like Lassa fever that are transmitted via contact with blood and other body fluids. We therefore assessed the knowledge, attitude and practice (KAP) of infection prevention and control (IPC) one year after an outbreak of nosocomial transmission of Lassa fever in the study hospital. Continue reading “Knowledge, attitude and practice of infection prevention and control among healthcare workers: one year after an outbreak of nosocomial Lassa fever in a tertiary hospital in southeast Nigeria”

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Review of Lassa fever, an emerging old world haemorrhagic viral disease in sub-Saharan Africa

O Azeez-Akande

 

Abstract

Lassa fever is an acute immunosuppressive illness of increasing public health concern causing severe morbidity and significant mortality (Case fatality rate (CFR) ≥ 50%) especially in epidemic cases. Although Lassa fever has emerged (following its first detection (1969) in Lassa town, Nigeria) as one of the most prevalent and debilitating viral haemorrhagic fevers endemic in West Africa region (Nigeria inclusive), yet, the control/prevention of the regular outbreak of the disease has become an herculean task in the areas affected; there is inadequate healthcare facility (including Laboratory/diagnostic and care centres), poor socioeconomic environment, lack of awareness among the populace and presence of favourable ecologic niche for the survival and propagation of the natural host and reservoir mouse (Mastomys natalensis) of Lassa virus . Lassa fever is mainly transmitted by contact with excretions and secretions of infected rats via foods and water as well as exposure to other contaminated items. Lassa virus is a member of an Old World Arenariruses, of family Arenaviridae. It is an enveloped, single-stranded (SS) bisegmented RNA virus with ability to replicate very rapidly. It consists of 4 lineages; 3 members are identified as ancenstral strains found in Nigeria, while the fourth is domiciled in other West Africa Countries. Lassa virus infects almost every tissue in human body resulting in multisystemic dysfunction. The incubation period is generally between 6 to 21 days resulting in 3 stages of clinical manifestation viz: Acute phase characterized by flu-like, non-specific illness; haemorrhagic phase accompanied with gastrointestinal symptoms and cardiovascular/neurologic complications. Currently, there is no clinically certified Lassa fever vaccine thus complicating deterrent or preventive measures. Hence, there is need for intensification of educational programs for the populace on the useful control measures against Lassa fever. The stakeholders need to prioritize intervention and support program and also speed up the processes leading to the production of effective vaccine to limit the menace of Lassa fever outbreak and associated morbidity, fatality and high socio-economic cost.

Keywords: Lassa fever, endemic, epidemic, reservoir rodent, West Africa

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Review of Lassa fever, an emerging old world haemorrhagic viral disease in sub-Saharan Africa