In our environment, PIDs are frequently underdiagnosed or easily missed because:
To improve data collection and relevant information on PIDs in South Africa, a PID registry was established in 2008. This is curated by Dr Monika Esser, a Paediatric Rheumatologist in charge of the Clinical Immunology service at Tygerberg Hospital. Employed by the National Health Laboratory Service at Tygerberg Hospital, Dr Esser is the prinicpal investigator of the registry at Stellenbosch University. The South African PID registry, apart from having ethical permission at SU, also has PIs and ethical approval at the University of Cape Town and the University of the Witwatersrand. Currently the registry has information on about 300 PID patients, a small fraction of the expected number of PID cases in the population. In Africa more broadly, there are estimated to be 900 000 individuals with a PID, but only several thousand have been diagnosed and registered to date. The SA registry diagnoses reflect a similar pattern of genetic disease to those of the European ESID registry with more than 50% related to antibody deficiencies. These conditions can be treated and major morbidity can be prevented by early
diagnosis.Improvements in the diagnosis of PIDs will result in earlier and appropriate treatment, in addition to the improved quality of life and survival of patients affected by these conditions. Defining genetic suceptibility to infections will also augment our understanding of the role of PIDs in the infections that are prevalent in developing country settings, such as Tuberculosis.
Tuberculosis is caused by an intracellular pathogen, Mycobacterium tuberculosis. Some PIDs are known to affect areas of the immune system that are crucial in the defence against Tuberculosis (TB) and other intracellular pathogens. Examples of such PIDs include Mendelian Susceptibility to Mycobacterial Diseases (MSMD) which are associated with infections of low- virulence Mycobacteria but also salmonellosis. Chronic Granulomatous Disease (CGD), and Severe Combined Immunodeficiency Disease (SCID) are further examples of PIDs which confer an increased risk of disease from TB. Investigation of patients with as yet unexplained recurrent Tuberculosis may yield further insights into both PIDs and the immunology of Tuberculosis.
Signs that a patient might have a PID include:
