Filariasis in Travelers Presenting to the GeoSentinel Surveillance Network

Background: As international travel increases, there is rising
exposure to many pathogens not traditionally encountered in the
resource-rich countries of the world. Filarial infections, a great
problem throughout the tropics and subtropics, are relatively rare
among travelers even to filaria-endemic regions of the world. The
GeoSentinel Surveillance Network, a global network of
medicine/travel clinics, was established in 1995 to detect
morbidity trends among travelers. Principal Findings: We examined
data from the GeoSentinel database to determine demographic and
travel characteristics associated with filaria acquisition and to
understand the differences in clinical presentation between
nonendemic visitors and those born in filaria-endemic regions of
the world. Filarial infections comprised 0.62% (n = 271) of all
medical conditions reported to the GeoSentinel Network from
travelers; 37% of patients were diagnosed with Onchocerca volvulus,
25% were infected with Loa loa, and another 25% were diagnosed with
Wuchereria bancrofti. Most infections were reported from immigrants
and from those immigrants returning to their county of origin (
those visiting friends and relatives); the majority of filarial
infections were acquired in sub-Saharan Africa. Among the patients
who were natives of filaria-nonendemic regions, 70.6% acquired
their filarial infection with exposure greater than 1 month.
Moreover, nonendemic visitors to filaria-endemic regions were more
likely to present to GeoSentinel sites with clinically symptomatic
conditions compared with those who had lifelong exposure.
Significance: Codifying the filarial infections presenting to the
GeoSentinel Surveillance Network has provided insights into the
clinical differences seen among filaria-infected expatriates and
those from endemic regions and demonstrated that O. volvulus
infection can be acquired with short-term travel.