PREDISPOSITION TO INVASIVE PNEUMOCOCCAL ILLNESS FOLLOWING PARA-INFLUENZA TYPE-3 VIRUS-INFECTION IN CHIMPANZEES

Abstract

An outbreak of invasive disease, including pneumococcal bacteremia, meningitis and pneumonia, involved 17 of 83 (20.5%) chimpanzees at a primate rehabilitation unit. Invasive disease was more common in splenectomized than in nonsplenectomized animals (42.9% vs. 18.4%), but the difference was not statistically significant. The outbreak followed closely an outbreak of upper respiratory tract infection (URTI) that occurred with equal frequency in splenectomized and nonsplenectomized chimpanzees. Those with URTI were 5.7 times as likely to develop invasive disease than those without URTI (P < 0.005). Fourteen of 20 (70%) chimpanzees with recent URTI and serologically examined had a 4-fold or greater rise in titer to parainfluenza type 3 virus. The outbreak of invasive disease occurred despite the fact that most of the chimpanzees had been vaccinated with pneumococcal vaccine. Efficacy of pneumococcal vaccine could not be demonstrated among any segment of the chimpanzee population and testing of sera from 23 vaccinated chimpanzees against 4 pneumococcal serotypes (3, 6, 8 and 14) failed to show a meaningful immune response. Viral URTI evidently can predispose primates to invasive infections and pneumococcal vaccine is not protective in chimpanzees.