ELW & LM performed the statistical analysis. pregnancy and at delivery, as well as in cord blood and from infants at age one year. Results Among the 711 pregnant women studied, 66% had at least one helminth infection at enrolment, 41% had hookworm, 20%?and 19%?exposure of the child to maternal helminth infection may have a long-term effect on the childs immunological development, including their response to immunisation [16,17]. Contrary to this hypothesis, within the Entebbe Mother and Baby study (EMaBS), we have shown that anthelminthic treatment during pregnancy had no effect on infant antibody levels following measles immunisation . However, we considered the possibility that maternal helminths might have other effects on the infant response that are not modified by treatment during pregnancy, or that other chronic immunomodulating infections such as HIV or malaria may influence the infant response to immunisation. We therefore explored these possibilities in an observational analysis within the EMaBS cohort, which had been established for a trial of anthelminthic treatment during pregnancy in Entebbe, Uganda. Methods Study setting and design The Entebbe Mother and Baby Study (EMaBS) was a larger, randomised, double-blind placebo controlled trial of treatment of helminths in pregnancy with albendazole versus placebo and praziquantel versus placebo in a 2×2 factorial design involving dMCL1-2 2507 pregnant women and their infants (trial registration number ISRCTN32849447). The study design and trial results have previously been reported [18,19]. For this study we conducted an observational analysis using samples and data that had been collected during the EMaBS. The aims of this observational analysis were 1. to investigate the hypothesis that maternal helminth infections influence maternal anti-measles antibody levels, and the infant response to measles immunisation, and 2. to investigate other factors associated with the infant response to measles immunisation Briefly, the study was based in Entebbe Hospital and recruited participants from Entebbe municipality and the adjacent Katabi sub-county, a population comprising urban, rural and fishing communities. Pregnant women in the second or third trimester were enrolled at Entebbe Hospital antenatal clinic if they were resident in the study area, planning to deliver in the hospital, willing to know their HIV status and willing to TNFSF13 take part in the study. They were excluded if they had evidence of possible helminth-induced pathology (severe anaemia, clinically apparent liver disease, bloody diarrhoea), if the pregnancy was abnormal, or if they had already enrolled during a previous pregnancy . Women gave written informed consent for their own participation and for the participation of their infant in the study. Women were followed up at delivery. Babies were followed up at immunisation visits, at age six, nine and 12?months and quarterly thereafter to age five years; annual follow up is still on-going. The babies were immunised at birth with the Bacille Calmette Guerin (BCG) dMCL1-2 and oral polio (OPV) vaccines; at 6, 10 and 14?weeks with OPV, The charcoal culture method was used to examine for Whole blood samples were examined for according to a modified Knotts method dMCL1-2  and for malaria by Leishman stained thick smears. HIV screeningHIV sero-status of the women was determined at enrolment into the study using a serial rapid testing algorithm as previously reported . For offspring of HIV positive women, HIV viral load was measured at six weeks of age dMCL1-2 using both DNA PCR and quantitative RT-PCR, to determine vertical HIV transmission. HIV antibody testing in infants was done at 18?months. Children were defined as HIV infected if found positive on.