Haemophilus influenzae meningitis

Haemophilus influenzae meningitis was first isolated by Pfeiter in 1892 from the nasopharyngeal secretions of an influenza patient. The vast majority of Haemophilus influenzae meningitis cases are caused by type b Haemophilus influenzae. Haemophilus influenzae typically resides in the upper respiratory tract of humans and infects only humans, with the peak age of onset being infants aged 3 months to 3 years. Infants under 2 months of age rarely develop the disease because they possess bactericidal antibodies from their mothers; thereafter, as age increases, maternal specific bactericidal antibodies decline while the child's own production of sufficient antibodies has not yet developed, making them susceptible to this disease. Children over 5 years of age and adults rarely develop the condition. If onset occurs after 5 years of age, attention should be paid to checking for anatomical or immunological defects. The disease can occur throughout the year but is most prevalent in autumn and winter. Cases of two children in the same family being affected simultaneously have also been frequently reported.