|
Several
Anopheles during a longer time window (2 weeks or more):
Correct answer. The epi curve shows three clusters of cases and exposure
periods.
|
Epi
curve showing 3 clusters of cases
|
Since P.
vivax has an incubation period of 12-17 days it is quite conceivable that there were several waves of infection, involving secondary transmission. In that scenario, the first patients were infected through the bites of local Anopheles. These patients later (after developing gametocytes)infected a second wave of mosquitoes, which, after a suitable maturation of the parasite (extrinsic cycle, duration 8-10 days,) were able to infect the next wave of local residents. This scenario would have been possible by the semi-tropical conditions existing in Palm Beach County at that time of year. The first local mosquitoes to become infected would have fed on a gametocyte carrier whose infection would have been acquired abroad (returning traveler or migrant).
Given the extended duration of the outbreak, "airport malaria" is a less likely hypothesis because such outbreaks would be expected to be single source (and thus of shorter duration).
Page last modified : April 23, 2004
Content source: Division of Parasitic Diseases
National Center for Zoonotic, Vector-Borne, and Enteric Diseases (ZVED)
|
|
|