Recent evidence suggests that low vitamin D concentrations are associated with increased levels of inflammatory markers. However, there are limited studies investigating associations between vitamin D levels and inflammatory markers in the general population and much of this evidence in older adults is inconclusive. Therefore, this study investigates the cross-sectional association of serum 25-hydroxyvitamin D (25(OH)D) levels with inflammatory markers in 5870 older English adults from wave 6 (2012–2013) of the English Longitudinal Study of Ageing (ELSA). ELSA is a large prospective observational study of community-dwelling people aged 50 years and over in England. Serum 25(OH)D levels, C-reactive protein (CRP) levels, plasma fibrinogen levels, white blood cell count (WBC), age, season of blood collection, waist circumference, total non-pension household wealth, measures of health and health behaviours that included depression, number of cardiovascular, non-cardiovascular conditions and difficulties in activities of daily living, smoking, and physical activity were measured. There was a significant negative association between low 25(OH)D levels (≤30 nmol/l) and CRP (OR 1·23, 95 % CI 1·00, 1·51) and WBC (OR 1·35, 95 % CI 1·13, 1·60) that remained after adjustment for a wide range of covariates of clinical significance. However, for fibrinogen, the association did not remain significant when waist circumference was entered in the final model. Our findings showed that 25(OH)D levels were associated with two out the three inflammatory markers investigated. The independent and inverse association between serum 25(OH)D levels and inflammation suggests a potential anti-inflammatory role for vitamin D in older English individuals from the general population.

The cumulative effect of co-infections between pathogen pairs on the haematological response of East African Short-horn Zebu calves is described. Using a longitudinal study design a stratified clustered random sample of newborn calves were recruited into the Infectious Diseases of East African Livestock (IDEAL) study and monitored at 5-weekly intervals until 51 weeks of age. At each visit samples were collected and analysed to determine the infection status of each calf as well as their haematological response. The haematological parameters investigated included packed cell volume (PCV), white blood cell count (WBC) and platelet count (Plt). The pathogens of interest included tick-borne protozoa and rickettsias, trypanosomes and intestinal parasites. Generalized additive mixed-effect models were used to model the infectious status of pathogens against each haematological parameter, including significant interactions between pathogens. These models were further used to predict the cumulative effect of co-infecting pathogen pairs on each haematological parameter. The most significant decrease in PCV was found with co-infections of trypanosomes and strongyles. Strongyle infections also resulted in a significant decrease in WBC at a high infectious load. Trypanosomes were the major cause of thrombocytopenia. Platelet counts were also affected by interactions between tick-borne pathogens. Interactions between concomitant pathogens were found to complicate the prognosis and clinical presentation of infected calves and should be taken into consideration in any study that investigates disease under field conditions.