Malaria, Mental Disorders and Immunity; and Their Inter-Relationships - A Cross Sectional Population Study in a Health and Demographic Surveillance Site in Kenya

Both malaria and mental disorders are associated with immune changes. We have previously reported the association between malaria and mental disorder in a household survey conducted in a health and demographic surveillance site of 70,000 population in an area endemic for malaria in western Kenya. We now report on the associations between malaria, mental disorders and immunity. We found marginally raised CD4/CD3 ratios of people with malaria parasites, but no difference in CD4/CD3 ratios for people with common mental disorder (CMD) or psychotic symptoms. People with psychotic symptoms had increased levels of IL-6. IL-8, and IL-10, and lower levels of IL-1beta. People with CMD had higher levels of IL-8 and IL-10. People with malaria had higher levels of IL-10 and lower levels of TNF-alpha. At the bivariate level, CMD was associated with log TNF-α levels using unadjusted odds ratios, but not after adjusting for malaria. Psychotic symptoms were associated with log IL-10 and log TNF-α levels at the bivariate level while in the adjusted analysis, log TNF-α levels remained highly significant. This is the first population based study of immune markers in CMD and psychotic symptoms, and the first to examine the 3 way relationship with malaria. Our findings suggest that TNF-α may mediate the relationship between malaria and CMD. Funding: The study was funded by UK Aid, Department for International Development, Kenya office. Declaration of Interest: The authors have no conflicts of interest to declare. Ethical Approval: Ethical approval was granted by the Kings College London and the Kenya Medical Research Institute Boards of Research Ethics respectively (PNM/11/12-54, SSC2374), and permission was obtained to conduct the study in households in Maseno area, which is part of the KEMRI/WRP Kombewa HDSS. Informed written and witnessed consent was asked of heads of sampled households, and then of sampled participants to take part in the study.