ABSTRACT. The recommended schedule for killed oral cholera vaccine (OCV) is two doses, 2 weeks apart. However, during vaccine campaigns, the second round is often delayed by several months. Because more information is needed to document antibody responses when the second dose is delayed, we conducted an open-label, phase 2, noninferiority clinical trial of OCV. One hundred eighty-six participants were randomized into three dose-interval groups (DIGs) to receive the second dose 2 weeks, 6 months, or 11.5 months after the first dose. The DIGs were stratified into three age strata: 1 to 4, 5 to 14, and > 14 years. Inaba and Ogawa vibriocidal titers were assessed before and after vaccination. The primary analysis was geometric mean titer (GMT) 2 weeks after the second dose. Data for primary analysis was available from 147 participants (54, 44, and 49 participants from the three DIGs respectively). Relative to the 2-week interval, groups receiving a delayed second dose had significantly higher GMTs after the second dose. Two weeks after the second dose, Inaba GMTs were 55.1 190.3, and 289.8 and Ogawa GMTs were 70.4, 134.5, and 302.4 for the three DIGs respectively. The elevated titers were brief, returning to lower levels within 3 months. We conclude that when the second dose of killed oral cholera vaccine was given after 6 or 11.5 months, vibriocidal titers were higher than when given after the standard period of 2 weeks. This provides reassurance that a delayed second dose does not compromise, but rather enhances, the serological response to the vaccine.

Background: Feco-oral transmitted diseases (FOTD) remain a public health issue, particularly in developing countries. Data concerning the carriage of Salmonella and intestinal parasites in children are available worldwide but are lacking in Cameroon. This study aimed to determine the asymptomatic carriage of Salmonella and intestinal parasites in children of two primary schools in Yaoundé. Methods: A cross-sectional descriptive study was conducted from October 2017 to May 2018 in two primary schools (from rural and urban areas) in the 7 th precinct of Yaoundé. Sociodemographic, clinical and paraclinical (rectal swab, direct examination of fresh stool and bacteriological culture on Hektoen medium) data were collected. Results: We included 368 (192 boys) pupils from both schools (184 in each school) with a mean age of 8.99 ± 2.21 years. None of the children was infected by Salmonella spp. Intestinal parasite prevalence was 9.80% (6.52% of children from the urban school vs 13.04% from the rural ones). The intestinal parasite prevalence tended to be higher in girls than in boys (11.98% vs. 7.39%). Among intestinal parasites, protozoa were the most widely found. Entamoeba histolytica and Giardia intestinalis were the most prevalent pathogenic intestinal protozoa (11.11% vs. 25% of all positive stool exams). The helminths, less frequent, were represented by Ascaris lumbicoides and Enterobius vermicularis. The factors associated with intestinal parasite carriage were mainly rural school location and age between 11 -13 years. Conclusion: Among children in primary school,