[1] Ctr Dis Control & Prevent, Div Parasit Dis, Natl Ctr Infect Dis, US Dept HHS,Publ Hlth Serv, Atlanta, GA 30341 USA
[2] Ist Super Sanita, Parasitol Lab, I-00161 Rome, Italy
[3] Duke Univ, Ctr Primate, Durham, NC USA
[4] N Carolina State Univ, Environm Med Consortium, Dept Clin Sci, Coll Vet Med, Raleigh, NC USA