Lassa virus

No approved vaccine exists for any of the VHP infections other than yellow fever. A Lassa virus vaccine currently under development at USAMRIID has shown good efficacy in nonhuman primates (Geisbert, 2005). Collaborative efforts between the Canadian Special Pathogens Program and researchers from USAMRIID have led to the development of an experimental filovirus vaccine that also provides protection to nonhuman primates in a laboratory setting (Feldmann, Jones, Schnittler, Geisbert, 2005). 

Kyasanur Forest virus 4. Arena viruses — Lassa virus... 

Buckley, S.M., Casals, J., Downs, W.G. Isolation and antigenic characterization of Lassa virus. Nature 1970 227 174. 

Winn, W.C.jr., Monath, T.R, Murphy, F.A., Whitfield, S.G. Lassa virus hepatitis. Observations on a fatal case from the 1972 Sierra Leone epidemic. Arch. Path. 1975 99 599-604... 

In West Africa, the arenavirus, Lassa Virus, causes Lassa Fever, responsible for 10-15% of adult febrile hospital admissions and up to 40% of nonsurgical deaths (48). The CDC estimates that Lassa virus infects 100,000-300,000 people annually, with approximately 5,000 deaths (50). Lassa causes pediatric disease as well as high mortality in pregnant women. Although nosocomial infections occur, most cases result from contact with the rodent species Mastomys natalensis (48). 

Biohazard level 4. Bolivian fever, Dengue fever, ebola, Hanta virus, Lassa virus, and other various hemorrhagic diseases (mostly of African origin). When dealing with biological hazards at this level the use of a Hazmat suit and a self-contained oxygen supply is mandatory, and the disease is studied and patient isolated in very rigorously self-contained environments. 

FIGURE 3.9 Lassa fever. Liver from a patient with Lassa fever. Scattered hepatocytes and reticuloendothelial cells show reactivity with monoclonal antibody to Lassa virus. (Naphthol fast red substrate and hematoxylin counterstain original magnification x100.)... 

Lassa virus causes Lassa fever, a major febrile disease of West Africa, where it is associated with 10% to 15% of adult febrile admissions to the hospital and perhaps 40% of nonsurgical deaths.1 In addition, Lassa fever is a pediatric disease and the cause of high mortality in pregnant women. While nosocomial infections do occur, most Lassa virus infections can be traced to contact with the carrier rodent, Mastomys natilensis. 

Trappier SG, Conaty AL, Farrar BB, Auperin DD, McCormick JB, Fisher-Hoch SP. Evaluation for the polymerase chain reaction for diagnosis of Lassa virus infection. Am J Trop Med Hyg. 1993 49 214-221. 

Lassa virus Junin virus Machupo virus Guanarito virus Sabia... 

The number of Lassa virus infections per year in West Africa is estimated at 100,000 to 300.000, with approximately 5.000 deaths. Unfortunately, such estimates are crude, because surveillance for cases of the disease is not uniformly performed. In some areas of Sierra Leone and Liberia, it... 

In what animal host is Lassa virus maintained ... 

The reservoir, or host, of Lassa virus is a rodent known as the "multimammate rat" of the genus Mastomys. It is not certain which species of Mastomys are associated with Lassa however, at least two species carry the virus in Sierra Leone. Mastomys rodents breed very frequently, produce large numbers of offspring, and are numerous in the savannas and forests of West. Central, and East Africa. In addition, Mastomys generally readily colonize human homes. All these factors together contribute to the relatively efficient spread of Lassa virus from infected rodents to humans. 

Approximately l5%-20% of patients hospitalized for Lassa fever die from the illness. However, overall only about 1% of infections with Lassa virus result in death. The death rates are particularly high for women in the third trimester of pregnancy, and for fetuses, about 95% of which die in the uterus of infected pregnant mothers. 

Individuals at risk are those who live or visit areas with a high population of Mastomys rodents infected with Lassa virus or are exposed to infected humans. Hospital staff are not at great risk for infection as long as protective measures are taken. 

Natural transmission of VHP to humans usually occurs from contact with infected animals, or through the bite of an infected insect vector such as a tick. The virus can also be spread by person-to-person transmission via any body fluid. Sexual transmission of Lassa virus has been reported. Lassa fever may also be spread by inhalation of airborne particles from the excretions of infected rodenis, although there is no documented evidence of human-to-human airborne transmission. 

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