Severe infections in pediatric intensive care unit are not uncommon. Historically, the diagnosis of hereditary (primary) immune deficiency required a combination of recurrent clinical signs and biological stigmas. This paradigm is currently being questioned, and grows the hypothesis of a potential underlying genetic susceptibility in any severe infection. To date, the proportion of severe infections explained by an underlying immune deficiency is unknown.

The aim of this prospective study is to assess the incidence of primary immune deficiencies in children with severe infection, regardless of their etiology.

Inclusion criteria:

• Inclusion age less than 16 years
• Inclusion age > 3 months of actual age for term infants and > 3 months for former preterm infants.
• Documented severe infection (bacterial, viral, fungal) at the University Hospital Center of Montpellier, Toulouse or Marseille
• Severe infections concerned by the study: any infection requiring hospitalization in pediatric intensive care (more than 24 hours) including:
• meninges or brain lesions, pleuro-pneumopathy, any infection associated with sepsis and/or an opportunistic germ, septic shock, etc.
• Encephalitis and encephalomyelitis of infectious origin
• Child benefiting from a social security system
• Collection of parental/legal representative consent

Exclusion criteria:

• Undocumented severe infections
• Acute bronchiolitis
• Children admitted with isolated SRV bronchiolitis without further complications from the infection;
• Previous comorbidity explaining the infection and/or stay in ICU/Continuing Care: Primary or known secondary immune deficiency; burns; risk factors for non-infectious epilepsy (encephalopathy, known epilepsy, head trauma), pneumonia caused by swallowing disorders or tracheotomy or chronic lung disease, asthma, meningitis favored by cochlear implants, breach of blood-brain barrier or neuromeningetic material, deep infection on implanted material or within 48h after surgery, cardiovascular decompensation; any other chronic conditions that may contribute to infection;
• Inability to obtain consent from parents/legal guardians.

Pediatric population

NC