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**1. Introduction** 

attention it deserves.

**2. Etiology/pathogenesis-**

**8** 

Ute Inegbenebor *Department of Physiology College of Medicine* 

*Nigeria* 

*Ambrose Alli University, Ekpoma* 

**Lassa Fever in the Tropics** 

Lassa fever is a frequently underestimated but socially and economically devastating disease. Lassa fever first came into limelight in 1969, when two nuns died as a result of complications of a hemorrhagic fever in Lassa town in the Borno State of Nigeria. Since then it has become endemic in many parts of West Africa. Out breaks of Lassa fever are usually associated with high mortality rates as the cases usually present late to the hospitals. Besides, many doctors find it difficult to diagnose Lassa fever until complications have set in because of the similarity of presentation to other more common febrile illnesses such as malaria and typhoid. In a study carried out in Sierra Leone in 1987, Lassa fever was found to be responsible for 10-16% of admissions and 30% of deaths in a major referral center. In another study of adult medical admissions in a special center for the management of Lassa fever in Nigeria in 2008, Lassa fever was responsible for 7% of admissions and 13% of deaths with a case fatality rate of 28%. However, the enlightenment campaign for the prevention of Lassa fever and diagnostic facilities are either lacking or rudimentary in most countries where Lassa fever is endemic. Compared to HIV/AIDS, Lassa fever is more infectious to close associates and it rapidly kills in dozens. However, Lassa fever does not get the global

Lassa fever is caused by Lassa fever virus, a member of the family Arenaviridae. It is an enveloped single stranded bi-segmented rna virus Replication for Lassa virus is very rapid, while also demonstrating temporal control in replication. There are two genome segments. The first replication step is transcription of messenger RNA copies of the negative- or minus sense genome. This ensures an adequate supply of viral proteins for subsequent steps of replication, as proteins known as N and L are translated from the mRNA. The positive- or plus-sense genome then makes viral complementary (vcRNA) copies of itself, which are + sense. The vcRNA is a template for producing minus sense progeny but mRNA is also synthesized from it. The mRNA synthesized from vcRNA are translated to make the G (spike) proteins and Z proteins. Thus, with this temporal control, the spike proteins, which are on the outside of the virus particle, are produced last, making the infection more difficult for the host immune system to detect. Nucleotide studies of the genome have shown that Lassa has four lineages: three found in Nigeria and the fourth in Guinea, Liberia, and Sierra

