Rodents have been associated with numerous severe epidemics in the past, prompting microbiologist ...

Answer: Rodents, among other animals, can serve as reservoirs and vectors of infectious diseases. Due to rodents' high reproductive rate, they can quickly propagate infectious diseases and in little time engender disease epidemics. Even if a disease is easily curable with a particular drug, it is still desirable to consider upstream efforts to eliminate the reservoir of an infectious disease, thus reducing human exposure to the disease agent. Currently emerging diseases such as hanta virus have a rodent reservoir and both plague and typhus can still cause significant numbers of cases worldwide.

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Answer: The host and pathogen both evolve and affect each other. As the pathogen evolves virulence factors, a host evolves defenses against them. This coevolution drives the establishment of a balanced equilibrium, which favors the survival of both the host and the pathogen. If this balance is not obtained, the host could be killed due to the infectious agent's pathogenicity, which would also in turn result in death of the pathogen as well.

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Answer: Common-source epidemics result from a single contaminated source, which can be transmitted in any possible manner. Host-to-host epidemics result from person-to-person contact. Common-source epidemics usually involve a large population of individuals suddenly becoming ill, and host-to-host epidemics generally have a more gradual increase and decrease in the number of diseased individuals.

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Answer: Caution should be taken to (1) not transfer any infectious agent to Kenya and (2) avoid becoming infected by a pathogen while in Kenya. A review on immunization status and medical records through consultation with an appropriate clinician should help to determine if one is ill and provide any vaccinations that are necessary. For example, an individual might be up-to-date on all necessary vaccinations for travel in the United States, but Kenya could have other infectious agents that Americans are not normally immunized against, such as typhoid and yellow fever. The CDC Information for Travelers also provides information regarding health concerns for international travel.

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Answer: The eradication of a disease requires that the pathogen be no longer transmitted. Because transmission of a disease such as rabies comes from wild animals that serve as reservoirs, all reservoirs would need to be removed for there to be no more transmission of the infectious agent. Immunizing or destroying all wild animals is not practical, so rabies remains very difficult to eradicate. Brucellosis and many other diseases are more easily eradicated because the reservoir is more easily controlled when, for example, they occur primarily in domesticated animals that can be tested, immunized, and or destroyed if infected.