surface antigens. Pattern of infection - Major outbreaks can be caused by any of the three types or subtypes, but

organisms on culture. (d) Cryptococcal - caused by cryptococcus neoformans mainly in patients with depressed immunity e. g. corticosteroids, diabetes, lymphoproliferative disorders, AIDS and infection in immuno-compromised patient. Symptoms occur intermittently over weeks and meningism is less common than confusion and depressed consciousness. Diagnosis by presence of C. neoformans in CSF, or detection of cryptococcal antigen. Tr. - Amphotericin B 0. 6-1 mg/kg/day iv or combination of amphotericin B 0. 3 mg/kg/day plus flucytosine 150 mg/kg/day. Fluconazole for cryptococcal meningitis in AIDS. (e) Acute syphilitic meningitis - (a) Mostly young men, (b) history of primary infection 1 -2 years ago, (c) may follow inadequate treatment or occur during specific therapy, (d) CSF - 1,000 or 1,500 cells, 30% or more polymorphs. CSF and blood serological tests for syphilis positive. (f) Leptospiral meningitis - (a) History of occupational relationship to rats. (b) Liver may be enlarged. (c) Jaundice may appear. (d) Conjunctival injection. (e) Hemorrhages common. (f) CSF - Leptospira may be demonstrated by culture. (g) Brucellosis - Meningitis is an uncommon complication of acute brucellosis. CSF besides lymphocytosis shows elevated protein and reduced sugar leve.l (h) Lyme disease - due to infection with spirochetal bacterium - Borrelia burgdorferi. Meningitis may be associated with erythematous rash called erythema chronicum migrans. Tr. - Tetracycline or penicillin. (i) Carcinomatous meningitis - More common in leukemias and lymphomas. Combination of altered mental state (e.g. confusion), cranial nerve signs (commonly optic, facial and those supplying eye muscles). Papilloedema common Back and limb pain due to radiculopathy. Also depressed reflexes, muscle wasting and sensory loss. Defferential Diagnosis of meningitis A Meningism - Neck stiffness in presence of normal CSF. May be seen occasionally usually at onset, in typhoid fever, apical pneumonia, acute exanthema, acute pyogenic tonsilitis, pyelo-nephritis or cervical lymphadenopathy. Meningitis common and more extensive Lumbar puncture at once differentiates 2. Acute disseminated meningoencephalitis - due commonly to HSV. Begins with features of acute meningitis and progresses rapidly to irritability, confusion, focal fits, coma and death. 3. Post-infectious meningoencephalitis- Rare sequel of measles or influenza, or less frequently chicken pox, mumps or rubella, and vaccines. Reccurent meningitis: Predisposing causes - (a) CSF leakage from prior head injury or congenital malformation predispose to recurrent pneumococcal meningitis. (b) Immunological defects may predispose to meningococcal disease. (c) Patients with primary antibody deficiency have susceptibility to enterovirus infections of CMS. (d) Echovirus infection may cause a progressive chronic meningoencephalitis 4 INFLUENZA Etiology - Causative agent - There are three immunological types of influenza viruses - two subtypes of A, A (H3N2) and A(H1,N1), and type B. The type A subtypes can be distinguished from each other by differences in their haemagglutinin (H) and neuraminidase (N) surface antigens. Pattern of infection - Major outbreaks can be caused by any of the three types or subtypes, but type A(H3N2) cause large scale mortality Individuals of all ages may be affected by this subtypes, but type B viruses principally infect children, adults less frequently In each patient, characteristics of influenza caused by the different virus types overlap such an extent, that determination of the virus involved is possible only through laboratory studies or knowledge of the