Some Common Causes of Fever in Children

Acute

Viral infections

< 28 days: TORCH infections (toxoplasmosis, other pathogens [varicella-zoster, parvovirus B19], rubella, cytomegalovirus [CMV], herpes simplex virus [HSV]), coxsackievirus, enterovirus, COVID-19 or other coronaviruses, HIV infection

≥ 1 month: Enterovirus and respiratory viruses (eg, respiratory syncytial virus, parainfluenza, adenovirus, influenza, rhinovirus, metapneumovirus, COVID-19 or other coronaviruses), CMV, Epstein-Barr virus (EBV), HSV, human herpesvirus 6

Bacterial infections (most common pathogens vary by age)

< 28 days: Group B streptococci, Escherichia coli and other enteric pathogens, Listeria monocytogenes (these organisms can cause bacteremia, pneumonia, pyelonephritis, meningitis, and/or sepsis; also, Salmonella species and Staphylococcus aureus [eg, in nursery outbreaks], which in addition to bacteremia and sepsis, can cause soft-tissue, bone, and joint infections), syphilis

1–3 months: Streptococcus pneumoniae, group B streptococci, Neisseria meningitidis, L. monocytogenes (these organisms can cause bacteremia, pneumonia, meningitis, and/or sepsis; other common infections include otitis media [S. pneumoniae, Haemophilus influenzae, Moraxella catarrhalis], urinary tract infection [E. coli and other enteric pathogens], enteritis [Salmonella species, Shigella and others], skin and soft-tissue infections [S. aureus, group A and B streptococci], bone and joint infections [S. aureus, Salmonella species])

3–24 months: S. pneumoniae, N. meningitidis (these organisms can cause bacteremia, meningitis, and/or sepsis; other common infections include otitis media and pneumonia [S. pneumoniae, H. influenzae, M. catarrhalis], urinary tract infection [E. coli and other enteric pathogens], enteritis [Salmonella species, Shigella and others], skin and soft-tissue infections [S. aureus, group A streptococci], bone and joint infections [S. aureus, Salmonella species, Kingella kingae])

> 24 months: S. pneumoniae, N. meningitidis (these organisms can cause bacteremia, meningitis, and/or sepsis; other common infections include otitis media, sinusitis, and pneumonia [S. pneumoniae, H. influenzae, M. catarrhalis, mycoplasma], pharyngitis or scarlet fever [group A streptococci], urinary tract infection [E. coli and other enteric pathogens], enteritis [Salmonella species, Shigella and others], skin and soft-tissue infections [S. aureus, group A streptococci], bone and joint infections [S. aureus, Salmonella species, K. kingae])

Mycobacterium tuberculosis in exposed or at-risk populations

Rickettsial infections in appropriate geographic locations

Other vector-transmitted infection (eg, Lyme disease)

Noninfectious

Kawasaki disease

Acute rheumatic fever

Heatstroke

Thermoregulatory disorders (eg, dysautonomia, diabetes insipidus, anhidrosis)

Toxic ingestions (eg, anticholinergics)

Vaccines

Medications

Fungal infections

Neonates or immunocompromised hosts: Candida species most common (urinary tract infection, meningitis, and/or sepsis)

Acute recurrent/periodic

Viral infections

Frequent or back-to-back minor viral illnesses in a young child

Periodic fever syndromes

Cyclic neutropenia

Periodic fever with aphthous stomatitis, pharyngitis, adenitis (PFAPA) syndrome

Familial Mediterranean fever (FMF)

TNF receptor–associated periodic syndrome (TRAPS)

Hyper-IgD syndrome (HIDS)

Chronic (fever of unknown origin)

Infectious*

Viral infections (eg, Epstein-Barr virus, cytomegalovirus, hepatitis viruses, arboviruses)

Sinusitis

Pneumonia

Enteric infections (eg, Salmonella)

Abscesses (intra-abdominal, hepatic, nephric)

Bone and joint infections (eg, osteomyelitis, septic arthritis)

Endocarditis

HIV infection (uncommon)

Tuberculosis (uncommon)

Parasitic infections (eg, malaria—uncommon)

Cat-scratch disease

Lyme disease (rarely causes chronic fever)

Noninfectious

Inflammatory bowel disease

Systemic rheumatic diseases (eg, juvenile idiopathic arthritis, systemic lupus erythematosus, acute rheumatic fever)

Cancer (most commonly lymphoreticular cancers such as lymphoma or leukemia but also neuroblastoma or sarcomas)

Medications

Thermoregulatory disorders (eg, dysautonomia, diabetes insipidus, anhidrosis)

Pseudo FUO

Factitious fever (eg, factitious disorder imposed on another)