Sample A: Cover Page of Thesis, Project, or Dissertation Proposal

emergence in the U.S. could result in a particularly severe outbreak because domestic
animals and wildlife in the U.S. are immunologically naïve to RVF virus.
Suitable Environmental Conditions
The role of environmental elements in the epidemiology of vector-borne diseases
such as RVF is well known. Environmental elements such as climate (e.g., temperature,
humidity, annual rainfall, intensity of rainfall), hydrology (e.g., proximity to lake/dam,
irrigation, accumulated water, proximity to river), and topography (e.g., elevation, land-
cover) influence vectorial capacity (House et al. 1992, Chevalier et al. 2004a, Turell et al.
2005, Clements et al. 2006). To have high vectorial capacity, which in turn increases the
probability of contact between hosts and vectors and the likeliness of RVF virus
establishment and spread, competent vectors must be in an environment suitable for vector
bioecology (e.g., population dynamics, biting activity and longevity) and virus transmission
(Turell et al. 2005).
Environmental conditions can affect the ability of mosquitoes to transmit arboviruses
such as RVF virus. For instance, the extrinsic incubation (EI) period (the time interval
between ingestion of the virus and subsequent transmission by the mosquito) of RVF virus
depends on ambient temperature (Brubaker and Turell 1998, Turell et al. 1985, Turell 1989,
House et al. 1992, Diallo et al. 2005). In general, studies have consistently shown that the EI
period is inversely related to temperature (Turell et al. 1985). However, the magnitude of the
effect of temperature on both infection and transmission rates appears to vary for different
virus-mosquito combinations (Turell et al. 1985).
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