Morbidity and mortality pattern in hospitalized children with sickle cell disorders at the University College Hospital, Ibadan, Nigeria

Objectives: To determine the causes of hospitalization and outcome of children with sickle cell disorders at the University CollegeHospital, Ibadan.Methods: Case files of patients with sickle cell disease who were admittedbetween March 2009 and February 2012 were analysed. Data extractedinclude demographic variables, diagnoses, types of crises, associated infections, complications and outcome of treatment.Results: There were 174 admissions of 161 children with a male femaleratio of 1.3:1. Their ages ranged from nine months to 18 years witha mean of 7.3(4.0) years. Vasoocclusive crisis was present in 107(61.5%), hyper haemolytic crisis in 29 (16.7%) and acute splenic  sequestration in 12 (6.9 %) of all admissions. Associated infectionswere septicaemia in 56 (32.2 %), malaria in 49 (28.2 %), acute osteomyelitis in 24 (13.8%), pneumonia in 23 (13.2%), urinary tract infection in 12 (6.9%) and septic arthritis in 10 (5.7%). Haematocrit was less than 15 % in 36 (20.7%) and blood transfusion administered in 68(39.1%) of admissions. There were three (1.7%) deaths from  cerebrovascular accident, adverse reaction to blood transfusion and meningitis.Conclusion: Prevention and prompt management of crises and infectionsin sickle cell disease is recommended to reduce morbidity andmortality

There Is No Safe Dose of Prions

Understanding the circumstances under which exposure to transmissible spongiform encephalopathies (TSEs) leads to infection is important for managing risks to public health. Based upon ideas in toxicology and radiology, it is plausible that exposure to harmful agents, including TSEs, is completely safe if the dose is low enough. However, the existence of a threshold, below which infection probability is zero has never been demonstrated experimentally. Here we explore this question by combining data and mathematical models that describe scrapie infections in mice following experimental challenge over a broad range of doses. We analyse data from 4338 mice inoculated at doses ranging over ten orders of magnitude. These data are compared to results from a within-host model in which prions accumulate according to a stochastic birth-death process. Crucially, this model assumes no threshold on the dose required for infection. Our data reveal that infection is possible at the very low dose of a 1000 fold dilution of the dose that infects half the challenged animals (ID50). Furthermore, the dose response curve closely matches that predicted by the model. These findings imply that there is no safe dose of prions and that assessments of the risk from low dose exposure are right to assume a linear relationship between dose and probability of infection. We also refine two common perceptions about TSE incubation periods: that their mean values decrease linearly with logarithmic decreases in dose and that they are highly reproducible between hosts. The model and data both show that the linear decrease in incubation period holds only for doses above the ID50. Furthermore, variability in incubation periods is greater than predicted by the model, not smaller. This result poses new questions about the sources of variability in prion incubation periods. It also provides insight into the limitations of the incubation period assay