Intended for healthcare professionals

Clinical Review

Lassa fever: epidemiology, clinical features, and social consequences

BMJ 2003; 327 doi: (Published 27 November 2003) Cite this as: BMJ 2003;327:1271

Rat eating, sexual transmission and the burden of Lassa fever disease

Eating Lassa virus infected rats and sexual intercourse could
definitely transmit infection but I think both methods have a limited role
as an important mechanism in sustaining the endemicity of the disease in
the population as described by sero-prevalence surveys and the clinical
disease burden.

The reason for this is that the subsequent disease from eating rats
will almost certainly cause rapidly fatal disease as a direct result of
the delivery of a very high dose of the virus into the person – a lethal
dose (LD) and so such persons will not contribute to the pool of sero-
positive persons detected during a sero-prevalence survey.

With sexual transmission, the presence of Lassa virus in seminal
fluid definitely suggests increased risk of transmission through sexual
intercourse but here I think the viral dose that the person is exposed to
might not be enough to cause clinical infection often enough to contribute
significantly to the burden of the clinical disease in these populations.

If these assumptions are found not to hold then I’ll suspect that
persons who survive an attack of Lassa after eating rats or persons that
succumb to much lower infecting doses (ID) of Lassa virus will be our
window into understanding the immunogenetics of surviving a LD of Lassa
and possibly the wider phenomenon of variable clinical response to Lassa
fever infection in the population.

Competing interests:
Babafemi Oshin currently works for Merlin as Country Medical Coordinator in Sierra Leone

Competing interests: No competing interests

09 December 2003
Babafemi A Oshin
Country Medical Coordinator, Merlin Sierra Leone
Freetown, Sierra Leone