Haemophilus Influenzae Biogroup Aegyptius - Characteristics and Case Definition

Characteristics and Case Definition

In his classic paper, Weeks characterizes H. aegyptius by its high contagiousness, direct transmission from patient to volunteer, pathogenesis, pathology, treatment and epidemiology. It manifests itself most often as BPF in infants and young children, aged 3 months to 8 years. Symptoms of Brazilian Purpuric Fever are usually preceded by purulent conjunctivitis and later include acute, or sudden, onset of high fever, vomiting, abdominal pain, purpura, vascular collapse and death. The overall patient fatality rate since the recognition of BPF is about 70%. The case definition of Brazilian Purpuric Fever is as follows:

1. An acute illness in a child aged between 3 months to 10 years characterized by:
   1. Fever of 101.3°F (38.5°C) or higher
   2. Abdominal pain and/or vomiting
   3. Development of petechiae and/or purpura
   4. No evidence of meningitis
2. History of conjunctivitis within the 30 days preceding the onset of fever
3. At least one of the following two tests negative for Neisseria meningitides:
   1. Blood cultures taken before antibiotic administration
   2. Serum or urine antigen detection

H. influenzae biogroup aegyptius is currently susceptible to a number of antibiotics. These include ampicillin, chloramphenicol, amoxicillin-clavulanic acid, cefamandole, cefuroxime, cefotaxime, tetracycline, ceftriaxone and rifampin. Health officials are hesitant in using systemic antibiotics like rifampin. Although they may help in treating the BPF clone, more studies should be done before this antibiotic is applied to more cases. Premature use of this antibiotic without further studies (and the use of rifampin to treat sporadic cases) could result in a potential development of resistance and excessive expenses. It is important to distinguish between H. influenzae biogroup aegyptius and the clone referred to as the “BPF clone.” The non-clone, typical version of H. aegyptius manifests itself in non-invasive conjunctivitis. The epidemic nature of this bacteria has been seen in the high frequency of “control” subjects from the affected areas of Brazil that have or had recently had conjunctivitis. These control subjects did not develop Brazilian Purpuric Fever, and therefore were probably not carrying the more dangerous BPF clone of H. influenzae biogroup aegyptius. Affected patients who had recently had conjunctivitis developed a fever and other symptoms of BPF within 1 to 60 days.