Contributing+Factors+-+Lassa+Fever

In Sierra Leone, there are several factors that make Lasa Fever and the Lasa virus more able to infect populations.

Rodents (Disease Vector)

 * Biologic: the multi-mammate rats are extremely common in equatorial Africa, a region which Sierra Leone is a part of.
 * Economic: Rodent control is less common and less economically unfeasible in Sierra leone because people have less economic wherewithal.
 * Social: multi-mammate rats are eaten as delicacies in many parts of Sierra Leone. This keeps the rodents nearer people and facilitates their exposure to the rodent excreta.
 * Environmental: The long rainy season can drive rats from the natural surroundings indoors for shelter and food. Indoors and without access to their natural food sources, the rats are driven to human grain stores where they deposit their excreta.

The Country (Sierra Leone)

 * Economic: The country was in the middle of a civil war and this internal tension further impoverished the poor country.
 * There are few facilities and few doctors who can safely deal with the virus.
 * In addition to the lack of resources and infrastructure, there was a lack of procedure for dealing with the disease.
 * Social: Because there are few doctors and facilities, people are often treated at home. This causes the chain of infection—in which the family too contracts the virus.
 * There is not complete access to media and only 72% have daily access to the radio—the most common way that people get information in the country.
 * Biologic and Environmental: There are a large variety of terrain in the country and provide habitats for many animal disease reservoirs (animals which are host to the pathogen but not affecte by it).

To Humans
The primary animal-human vector, the multi-mammate rat is not only extremely common in equatorial Africa, but in some parts of Sierra Leone, is eaten as a delicacy. During the long rainy season, the rodent may seek shelter indoors and there come into contact with with human grain stores or food preparation areas. That this vector is brought into contact with humans and their food sources in several ways: through intentional consumption and through environmental factors creates a double threat for zoonotic transmission to humans.

Because there are a lot of packed dirt surfaces, against which the rodent's excreta (urine and feces) are difficult to see, there is the additional chance of contracting the disease through contact with rodent excreta.

Between Humans
Worldwide, there is no human vaccine for Lasa virus. There is medication to treat the fever (ribavirin) but for greatest efficacy (reduction of mortality from the virus from ~50% to ~5–10%) it must be administered intravenously for almost a week after exposure. Because the symptoms of the virus are nearly indistinguishable from those of other hemorrhagic fevers and from malaria, it is not always possible to determine whether the infectious agent is the Lasa virus without sending blood samples to a lab for RT-PCR analysis which is expensive and often impossible in rural and economically disadvantaged areas.

In addition to this lack of western medicine, there is a lack of healthcare facilities which further compounds the effect of the virus and makes a population more likely to experience an outbreak. Because people cannot go somewhere with people trained in treating and encountering contagious diseases, they must be treated in the home. From a lack of access to healthcare facilities and medicine stems an opportunity for the virus to infect a whole family rather than just an individual.



=Sources= http://wwwnc.cdc.gov/travel/yellowbook/2012/chapter-3-infectious-diseases-related-to-travel/viral-hemorrhagic-fevers.htm http://en.wikipedia.org/wiki/Lassa_fever http://www.virologyj.com/content/8/1/205 http://books.google.com/books?id=QZl7GzhTsb8C&lpg=PA119&ots=3mTOUxnz3k&dq=ribavirin%20in%20sierra%20leone&pg=PA119#v=onepage&q=ribavirin%20in%20sierra%20leone&f=false

What factors contributed to the outbreak of the disease? Consider biological, environmental, cultural, etc.