Paediatric assessment of immune responses in 3 to 5 years olds having intestinal nematode infection and vaccinated with valent10-PCV

Abstract

Valent 10 - Pneumococcal conjugate vaccine (PCV10) introduction into routine immunization schedule has resulted in reduction of the incidence of Invasive Pneumococcal disease (IPD) in children in Kenya. This study assessed immunological effect of nematode infection in children aged 3 to 5 years vaccinated with PCV10. The study subjects were from Mukuru Kwa Njenga settlement in Nairobi County, Kenya. The children were medically examined for the presence of other infectious diseases by a qualified clinical officer. Questionnaires on the PCV10 vaccination history and deworming history of children were administered to the parents or guardians of children with the help of community health workers. The intensity of nematode infections was examined in the faecal samples using Kato-Katz technique and expressed as eggs per gram (EPG) of faeces. Serum samples were obtained from blood collected during sampling and used in Flow cytometry to determine levels of IL-2, IL-4, IL-6, IL-10, TNF-α and IFN-γ in cellular immune responses, whereas, ELISA was used to determine the levels of IgG and IgE antibodies in humoral responses. Results showed 73.4% of children completed the PCV10 vaccination dose schedule, 21.6% of children sampled had suffered invasive pneumococcal infections post PCV10 vaccination. Ascaris lumbricoides was the only species identified in 34.9% of children having light to moderate infection intensity with mean intensity of 17808EPG. Significant IL-6 levels expressed in children having nematode infection impacted increased secretion of IgG and IgE, thus, an indication that the humoral responses were significantly stimulated. Results indicate suppression of TNF-α expression in the category of children who had nematode infection and were also vaccinated with PCV10, however, a higher expression of IFN-γ in the same category implied a negative impact on PCV10 responses. The study also indicated that presence of nematodes and vaccination had a profound influence on the expression of IL-2, however, PCV10 vaccination and intestinal nematode infection did not significantly impact the expression of IL-4 and IL-10 cytokines. Immune responses due to infection with Ascaris lumbricoides stimulated multiple effector mechanisms influencing induction of cellular responses in PCV10 vaccination. Further investigation of other key cytokines as well as other parasites and pneumonia vaccines in other vulnerable individuals is therefore necessary in the management of concomitant infections in order to reduce the suppression of immune responses often resulting in difficulties in disease management.