Lassa fever epidemiology and demographics: Difference between revisions
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==Epidemiology and Demographics== | ==Epidemiology and Demographics== | ||
Lassa virus is [[zoonosis|zoonotic]] (transmitted from animals), and that it spreads to man from [[rodent]]s, specifically multi-mammate rats (''[[Mastomys natalensis]]''). This is probably the most common rodent in equatorial Africa, ubiquitous in human households and eaten as a delicacy in some areas. In these rats infection is in a persistent [[asymptomatic]] state. The virus is shed in their excreta (urine and feces), which can be | Lassa virus is [[zoonosis|zoonotic]] (transmitted from animals), and that it spreads to man from [[rodent]]s, specifically multi-mammate rats (''[[Mastomys natalensis]]''). This is probably the most common rodent in equatorial Africa, ubiquitous in human households and eaten as a delicacy in some areas. In these rats infection is in a persistent [[asymptomatic]] state. The virus is shed in their excreta (urine and feces), which can be [[aerosol]]ized. In fatal cases, Lassa fever is characterized by impaired or delayed cellular immunity leading to [[fulminant]] [[viremia]]. | ||
The dissemination of the infection can be assessed by prevalence of antibodies to the virus in populations of: | The dissemination of the infection can be assessed by prevalence of antibodies to the virus in populations of: | ||
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Like other [[Viral hemorrhagic fever|hemorrhagic fevers]], Lassa fever can be transmitted directly from one human to another. It can be contracted by an airborne route or with direct contact with infected human blood, urine, or semen. Transmission through [[breast milk]] has also been observed. | Like other [[Viral hemorrhagic fever|hemorrhagic fevers]], Lassa fever can be transmitted directly from one human to another. It can be contracted by an airborne route or with direct contact with infected human blood, urine, or semen. Transmission through [[breast milk]] has also been observed. | ||
About 15%-20% of hospitalized Lassa fever patients will die from the illness. It is estimated that the overall mortality rate is 1%, however during [[epidemic]]s mortality can climb as high as 50%. Also the mortality rate is higher, greater than 80%, when it occurs in pregnant women during their third trimester; fetal death also occurs in nearly all those cases. Abortion decreases the risk of death to the mother. It is estimated that the virus is responsible for about 5,000 deaths annually. The fever accounts for up to one third of deaths in hospitals within the affected regions and 10 to 16% of total cases. | About 15%-20% of hospitalized Lassa fever patients will die from the illness. It is estimated that the overall mortality rate is 1%, however during [[epidemic]]s mortality can climb as high as 50%. Also the [[mortality rate]] is higher, greater than 80%, when it occurs in pregnant women during their [[third trimester]]; [[fetal]] death also occurs in nearly all those cases. [[Abortion]] decreases the risk of death to the mother. It is estimated that the virus is responsible for about 5,000 deaths annually. The fever accounts for up to one third of deaths in hospitals within the affected regions and 10 to 16% of total cases. | ||
The number of Lassa virus infections per year in West Africa is estimated at 100,000 to 300,000. Unfortunately, such estimates are crude, because [[disease surveillance|surveillance]] for cases of the disease is not uniformly performed. In some areas of Sierra Leone and Liberia, it is known that 10%-16% of people admitted to hospitals have Lassa fever, which indicates the serious impact of the disease on the population of this region. | |||
==References== | ==References== | ||
{{Reflist|2}} | {{Reflist|2}} | ||
Revision as of 17:06, 20 December 2012
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Epidemiology and Demographics
Lassa virus is zoonotic (transmitted from animals), and that it spreads to man from rodents, specifically multi-mammate rats (Mastomys natalensis). This is probably the most common rodent in equatorial Africa, ubiquitous in human households and eaten as a delicacy in some areas. In these rats infection is in a persistent asymptomatic state. The virus is shed in their excreta (urine and feces), which can be aerosolized. In fatal cases, Lassa fever is characterized by impaired or delayed cellular immunity leading to fulminant viremia.
The dissemination of the infection can be assessed by prevalence of antibodies to the virus in populations of:
- Sierra Leone 8–52%
- Guinea 4–55%
- Nigeria approx. 21%
Like other hemorrhagic fevers, Lassa fever can be transmitted directly from one human to another. It can be contracted by an airborne route or with direct contact with infected human blood, urine, or semen. Transmission through breast milk has also been observed.
About 15%-20% of hospitalized Lassa fever patients will die from the illness. It is estimated that the overall mortality rate is 1%, however during epidemics mortality can climb as high as 50%. Also the mortality rate is higher, greater than 80%, when it occurs in pregnant women during their third trimester; fetal death also occurs in nearly all those cases. Abortion decreases the risk of death to the mother. It is estimated that the virus is responsible for about 5,000 deaths annually. The fever accounts for up to one third of deaths in hospitals within the affected regions and 10 to 16% of total cases.
The number of Lassa virus infections per year in West Africa is estimated at 100,000 to 300,000. 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 is known that 10%-16% of people admitted to hospitals have Lassa fever, which indicates the serious impact of the disease on the population of this region.