Haemophilus Meningitis

Meningitis caused by Haemophilus influenzae, historically the leading cause of bacterial meningitis in young children before the introduction of the Hib (Haemophilus influenzae type b) conjugate vaccine, which has reduced invasive Hib disease incidence by over 90% in populations with good vaccine coverage. In unvaccinated populations, or where vaccine coverage is incomplete, it remains an important cause, predominantly affecting children under 5. Non-typeable and other capsular type strains (non-b) have become relatively more prominent in the post-vaccine era, and can also cause invasive disease, particularly in the very young, elderly, or immunocompromised.

Presentation follows the general pattern described in the Meningitis entry: fever, headache, neck stiffness, photophobia, and altered consciousness, with the specific pattern in young children often being less classic (irritability, poor feeding, lethargy, a bulging fontanelle in infants, rather than clearly localizable neck stiffness). Associated invasive Hib disease may include epiglottitis (a specific airway emergency, drooling, stridor, and respiratory distress) or septic arthritis, which can occur concurrently or independently.

Lumbar puncture with CSF analysis as detailed in the general Meningitis entry, showing a bacterial pattern (elevated opening pressure, neutrophilic pleocytosis, elevated protein, low glucose relative to serum). Gram stain may show small gram negative coccobacilli. CSF and blood culture confirm the diagnosis and allow susceptibility testing. Rapid antigen testing is available in some settings but has largely been superseded by culture and, increasingly, PCR based multiplex meningitis/encephalitis panels where available, given superior sensitivity and speed.

Empirical treatment should not await confirmation and follows the general bacterial meningitis approach detailed in the Meningitis entry: ceftriaxone 2 g IV bd (adults; weight-based dosing in children, commonly 50 mg/kg bd, maximum 4 g/day), given the high prevalence of beta-lactamase producing strains that would otherwise render ampicillin ineffective
Dexamethasone given with or just before the first antibiotic dose (0.15 mg/kg IV every 6 hours for 4 days in children, adult dosing per local protocol), given clear evidence of reduced hearing loss and neurological sequelae specifically with Hib meningitis, one of the strongest evidence bases for adjunctive steroid use across bacterial meningitis causes
Total treatment duration typically 7 to 10 days, guided by clinical response
Chemoprophylaxis for close contacts: rifampicin (20 mg/kg once daily for 4 days in children, 600 mg once daily for 4 days in adults) is recommended for household contacts where a vulnerable individual (unvaccinated or incompletely vaccinated child under 4, or an immunocompromised household member) is present, given the risk of secondary transmission
Vaccination review: confirm and, where indicated, complete Hib vaccination status of the index case's close contacts, since the diagnosis often reflects a gap in vaccine coverage

Referral: infectious disease and, in children, pediatric input for all cases; ENT emergency assessment if concurrent epiglottitis is suspected, given the airway risk.

Rift Valley Fever

Also known as: RVF

Rift Valley fever is a viral hemorrhagic fever caused by a phlebovirus, endemic to parts of sub-Saharan Africa and the Arabian Peninsula, primarily affecting livestock (with associated significant agricultural and economic impact during outbreaks) but capable of causing human infection and, periodically, significant human outbreaks.

Transmission occurs through mosquito bites, or, more commonly in human cases during livestock outbreaks, through direct contact with the blood, body fluids, or tissues of infected animals, which is why abattoir workers, veterinarians, and herders are at particularly elevated risk during epizootic periods.

The large majority of human infections are asymptomatic or cause a mild, self limiting febrile illness, and it is this mild presentation that accounts for most cases, with severe disease occurring in only a small minority.

The typical mild illness presents with fever, headache, myalgia, and malaise, generally resolving within a week without specific treatment.
A small proportion of patients progress to more severe complications, which define the clinically important minority of cases: ocular disease, with retinal lesions that can cause permanent visual impairment, typically becoming apparent one to three weeks after the initial illness; hemorrhagic fever, with jaundice, bleeding manifestations, and hepatic involvement, carrying significant mortality; and encephalitis, presenting with confusion, seizures, or focal neurological deficit, typically occurring somewhat later in the illness course than the hemorrhagic complications.

Diagnosis is confirmed through RT-PCR detection of viral RNA, most sensitive early in the illness during the viremic phase.
Serology (IgM and IgG) supports diagnosis, particularly useful once the acute viremic window has passed, with IgM indicating recent infection.
FBC and LFTs support assessment of severity, particularly relevant in suspected hemorrhagic presentations, where thrombocytopenia and deranged liver function may be present alongside coagulopathy.
A relevant epidemiological context, livestock exposure, residence in or travel to an endemic or outbreak affected area, is an essential part of the diagnostic picture given the non-specific nature of the illness in isolation.

Differentials include other viral hemorrhagic fevers, malaria, and other causes of an acute febrile illness, with the specific epidemiological exposure context helping to narrow this differential considerably.

No specific antiviral treatment is established, and management is entirely supportive.

Mild disease requires only symptomatic treatment: rest, hydration, and antipyretics or analgesics, avoiding NSAIDs and aspirin where a hemorrhagic complication cannot yet be excluded, given the bleeding risk these agents carry.
Severe hemorrhagic disease requires the same principles of supportive care applied to other viral hemorrhagic fevers: careful fluid and electrolyte management, blood product support for significant bleeding or coagulopathy, and close monitoring for progression, generally in a higher level care setting.
Ocular involvement requires ophthalmological assessment and follow up, given the risk of permanent visual impairment from retinal lesions.
Encephalitis is managed supportively, following general principles applicable to viral encephalitis of other causes.
Prevention centers on vector control, personal protective measures against mosquito bites in endemic and outbreak affected areas, and, critically, appropriate protective equipment and precautions for those handling livestock or animal tissues during outbreak periods, alongside livestock vaccination programs (used in animals rather than routinely in humans, given that human vaccines remain primarily investigational or reserved for specific high risk occupational groups in some settings) as part of broader One Health outbreak control efforts.

Referral: infectious disease or tropical medicine input for confirmed or suspected cases, particularly severe presentations; ophthalmology for any suspected ocular involvement; public health notification given the outbreak potential and the need for coordinated human and veterinary public health response.

Haemophilus Meningitis

Overview

Clinical Features

Diagnosis

Management

Overview

Clinical Features

Diagnosis

Management