Helicobacter pylori infection is usually acquired in childhood, but precise estimates of the age of acquisition are difficult to obtain in young children. Since serial endoscopic biopsies are not feasible in human infants, we examined acquisition of H. pylori infection that is known to occur in socially housed nonhuman primates. By 12 weeks of age, 8 of 20 newborns (40%) were culture positive for H. pylori, and prevalence reached 90% by 1 year of age. Newborns from infected dams were more commonly infected than those from uninfected dams, particularly during the peripartum period, suggesting that close contact during this time may facilitate transmission. Transient infection was uncommon and occurred only after the first positive culture. These results suggest that in a high-prevalence environment, persistent H. pylori infection may be acquired at an earlier age than was previously thought. Since clean, potable water was readily available, contamination of water supply is not essential for widespread infection at an early age in areas where hygiene is otherwise poor. Furthermore, breastfeeding seems to offer little protection, since newborn macaques breastfeed during the first year of life and typically are fully weaned only when another newborn arrives the following spring.

Socially housed rhesus monkeys rapidly acquired Helicobacter pylori infection, although the organism was rarely cultivated from saliva, feces, or the environment. Since the concentrations of H. pylori in vomit were compatible with what is known about the infectious dose, our results are most consistent with an oral-oral means of transmission.