This stimulates immunity, but the bacilli do not survive within the cells, as they lack the essential

antibody (c) Ty21a-oralvaccine-TY21ais a galactose epimerase mutant S. typhi given as oral enteric coated capsules. The bacilli invade mononuclear cells and undergo 4-5 cell divisions in intestinal tract. This stimulates immunity, but the bacilli do not survive within the cells, as they lack the essential enzyme UDP-galactose^4- epimerase and are therefore avirulent. The vaccine stimulates cell mediated immunity and also stimulates intestinal IgA. Dose - One capsule on days 1, 3 and 5 irrespective of age one hour before meal with milk or water. Not recommended for children under 6 years of age. Protection commences 2 weeks after last capsule and lasts for atleast 3 years. Contraindications - Immunodeficiency states including treatment with immunosuppressive and antimitotic drugs, acute febrile illness and acute intestinal infection. Adverse reactions - Mild Gl disturbance, transient exanthema. 6. PLAGUE Epidemiology - Causative organism - Gram negative bacilli Yersinia pestis. Transmission - It is normally transferred from rodent to rodent (in whom it is enzootic) by fleas. Man can be infected through the infected flea or occasionally by louse or bedbug, and sometimes from droplet infection from cases of pneumonic plague. Permanent immunity results from an attack. Incubation period - 2-4 days. Clinical Features - 1. Bubonic plague - commonest variety. (a) Stage of invasion - Bodyache, mental confusion. Bubo appears on second or third day, usually in groin. Very tender and associated with cellulitis of surrounding tissues. (b) Febrile stage - Onset may be with high fever without prodromata. The temperature continues as a high remittent fever for 2-5 days and then falls suddenly, or gradually after 3-4 days, synchronous with the full development of the buboes. It may rise again if and when the buboes suppurate. Congested eyes, speech dull resembling alcoholic intoxication. Marked prostration, delirium, vomiting and oliguria, retention of urine, coma and convulsions may occur. Thready pulse, dilatation of heart and perhaps hemorrhages in later stages. Spleen and liver enlarged. Death may occur on third or fifth day. (c) Stage of recovery - Constitutional symptoms abate usually on 10th day with fall of temperature and perspiration. Bubo continues to enlarge and may burst, or suppuration may not occur. 2. Primary pneumonic - Rigor, malaise, vomiting, fever, and prostration. Chest pain, dry cough, dyspnoea and cyanosis with profuse, watery, blood tinged sputum. Hemorrhages frequent. 3. Septicemic - Systemic dissemination via blood stream with involvement of many organs. Hematogenous invasion of lungs results in secondary pneumonic plague. UNUSUAL PRESENTATIONS - Cervical bubonic plague - less common than inguinal, femoral or axillary forms. Carbuncular plague - presents with ulcerating skin lesion. Meningitis - may be the presenting feature and is diagnosed by isolation of Y pestis from CSF Laboratory diagnosis 1 White cell count - Leucocytosis with absolute predominance of neutrophils 2 Detection of Y pestis - in material from glands, blood (in septicemic form), sputum (in pneumonic cases), or discharge, by smear or culture. 3. Serology - Haemagglutinating antibodies appear within one week of onset of illness and specific IgM and IgG can be demonstrated by EL ISA techniques Management -1 Specific - (a) Streptomycin 30 mg/kg/day IM in 2 divided doses for 10 days to prevent relapse. (b) Tetracycline if allergy to streptomycin 2-4 g/day in 4 divided doses for 10 days (c) Chloramphenicol - for patients with meningitis 25 mg/kg loading dose IV followed by GO mg/kg in 4 divided doses and after clinical improvement continued orally for 10 days. 2. Local - In early stages buboes painted with iodine, or glycerine and belladona, or treated with infra-red rays. Opened only when they point, allowed to drain, and dressed with antibacterial powder. 3. General - Good nursing. Sedatives for pain and restlessness. Pneumonic plague patients must be strictly isolated to prevent droplet infection. Immunization - Vaccine containing 2,000 million killed organisms per ml. 0.5followed by 1 ml. after 7-10 days. Immunity lasts for G-12 months. Protection of contacts -Tetracycline 500 mg 6-houhy for 5 days for close contacts of plague patients or those believed to be incubating the disease. 7. BRUCELLOSIS Definition -Brucellosis is a zoonosis usually caused by Brucella melitensis, Brucella suis, or Brucella abortus (in decreasing order of virulence in man). Brucellae are small, non-motile, coccobacilli. Epidemiology - Organism - Intracellular parasite belonging to the genus brucella. Transmission - (a) Consumption of infected unsterilised milk, and its products. (b) Milking or tending infected animals, particularly those infected animals which have delivered or aborted Organisms may enter the body through cuts and abrasions on the hands, conjunctivae or respiratory tract. (c) Handling carcasses or meat of infected animals in abbatoirs, butchers. Veterinarians and microbiology workers are also at risk. (d) Sexual transmission may occur in man. Age - Rare below age of 15, three times more common in men. Incubation period 2-4 weeks. (7-10 days following accidental inoculation). Clinical features - 1 Acute brucellosis - fa) NON-SPECIFIC EARLY FEATURES - Period of ill-health for about 2 weeks with fever.