Anatomy and Function of Lymphoid Tissue The lymphoid system is composed of an extensive capillary network that drains lymph into elaborate systems of collecting vessels. The collecting vessels merge and empty lymph into the bloodstream by way of the thoracic…
Optimal evaluation of patients with prolonged, recurring, or periodic fever requires extensive review of signs and symptoms to establish the onset and cardinal features of illness, to define the exact fever pattern, and to understand the context of illness within…
Most young children with fever and no apparent focus of infection have self-limited viral infections that resolve without treatment and are not associated with significant sequelae. However, a small proportion of young children with fever who do not appear to…
Generally, in differentiating between bacterial and viral causes of febrile illnesses in children, the more mucous membranes involved in the patient’s illness (e.g., conjunctiva, throat, respiratory, gastrointestinal tract), the more likely the cause is viral. When multiple mucous membranes are…
Hemophagocytic lymphohistiocytosis (HLH) is a hyperinflammatory syndrome characterized by the accumulation of activated T lymphocytes and well-differentiated macrophages (histiocytes) in the bone marrow, lymph nodes, liver, spleen, and, often, the central nervous system (CNS). , HLH is a rare disease…
Epidemiology Sepsis remains a major cause of morbidity and mortality among children across the globe. In the US, the estimated incidence annually is 1 case per 1000 persons, an increase compared with prior years. , , Sepsis now accounts for…
Fever Fever is defined as a centrally mediated rise of body temperature above normal daily variation in response to various stimuli. , The classic definition for fever includes a rectal temperature ≥38°C (100.4°F). An excess of the body temperature above…
The human immune system has evolved to protect an individual from infectious microbes. It does this by using a complex interactive network of cells, proteins, and organs. Rapidly expanding research of inborn errors of immunity has taught us that despite…
More than 1.4 billion people travel internationally each year, approximately 10% of whom are children. Although travel can expose children to some risks, the benefits are many. A careful pretravel evaluation to provide appropriate guidance and preparation is critical to…
Chemoprophylaxis is prevention of disease by administration of an anti-infective drug product. An antimicrobial product is given to an individual who is at risk of developing an infection following exposure to bacteria, viruses, fungi, mycobacteria, or parasites. The term “prophylaxis”…