Typhoid Fever Ppt
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TYPHOID FEVER & CONTROL MEASURES
Mary Mallon (wearing glasses) photographed with bacteriologist Emma Sherman on North Brother Island in 1931 or 1932, over 15 years after she had been quarantined there permanently.
In 1906, Irish immigrant Mary Mallon worked as a cook in the Oyster Bay summer home of New York banker Charles Henry Warren and his family. By the end of the summer, six members of the household had contracted typhoid fever. The Warrens hired sanitary engineer, George Soper, to determine the source of the disease. Soper concluded that Mallon, while immune herself to the disease, was its carrier. For three years, she was isolated on North Brother Island, near Rikers Island, earning the nickname "Typhoid Mary." Instructed not to cook for others upon her release, she nevertheless changed her name and became a cook at a maternity hospital in Manhattan. At least 25 staff members contracted typhoid. "Typhoid Mary" returned to North Brother Island, where she lived alone for 23 years, until her death in 1938. She is shown here on the island in an undated photo. She died of a stroke after 23 years in quarantine.
Typhos in Greek means ,smoke and typhus fever got its name from smoke that was believed to cause it. Typhoid means typhus-like and thus the name given to this disease.The term Typhoid was given by Louis 1829 to distinguish it from typhus fever. It is a disease of poor environmental sanitation and hence occurs in parts of the world where water supply is unsafe and sanitation is substandard.
The term enteric fever or typhoid fever is a communicable disease, found only in man and includes both typhoid fever caused by S.Typhi and paratyphoid fever caused by S.Paratyphi A, B and C . It is an acute generalized infection of the reticulo endothelial system, intestinal lymphoid tissue, and the gall bladder.
According to the World Health Organization, globally some 16 million cases occur annually resulting in more than 600,000 deaths. More than 62% of the global cases occur in Asia, of which, 7 million occur annually in South East Asia. Other countries with a high incidence include Central and South America, Africa and Papua New Guinea.
The incidence of this disease in UK is reported to be just one case per 1,00,000 population.In 1994, for example, 26,55,000 cases (incidence : 500 cases/ million) were reported from Africa with 1,30,000 deathsThe mean incidence of typhoid fever in developing countries is estimated between 150 cases/million population/year in Latin America to 1000cases/million population/year in some Asian countries.
IndiaWorld largest outbreak of typhoid in SANGLI on December 1975 to February 1976 . This disease is endemic in India1992 : 3,52,980 cases with 735 deaths1993 : 3,57,452 cases and 888 deaths1994 : 2,78,451 cases and 304 deathsCase fatality rate due to typhoid has been varying between 1.1% to 2.5 % in last few years.
In 1885, pioneering american veterinary scientist, daniel E. Salmon, discovered the first strain of salmonella from the intestine of a pig. This strain was called salmonella choleraesuis, It is still used to describe the genus and species of this common human pathogen.
In 1880s, the typhoid bacillus was first discovered by Eberth in spleen sections and mesenteric lymph nodes from a patient who died from typhoid. Robert Koch confirmed a related finding and succeeded in cultivating the bacterium in 1881.Serodiagnosis of typhoid was thus made possible by 1896. Wright and his team prepared heat killed vaccine from S.Typhi in 1896
Salmonellae are gram ve rods, facultatively aerobic, Motile with peritrichate flagella, non-spore-forming1-3m 0.5m in sizeSalmonella currently comprise 2000 serotypesTwo groups a) Enteric fever group b) Food poisoning groupThe bacilli are killed at 55c in one hour or at 60c in 15 minutes.They are killed within 5 minutes by mercuric cholride or 5% phenolBoiling or chlorination of water and pasteurization of milk destroy the bacilliThe proportion of typhoid to paratyphoid A is 10:1, Paratyphoid B is rare and paratyphoid C is very rare in India
Age group : Typhoid fever may occur at any age but it is considered to be a disease mainly of children and young adults. In endemic areas, the highest attack rate occurs in children aged 8-13 years. In a recent study from slums of Delhi, it was found that contrary to popular belief, the disease affects even children aged 1-5 years
Gender and race : Typhoid fever cases are more commonly seen in males than in females. On the contrary, females have a special predilection to become chronic carriers. Occupation : Certain categories of persons handling the infective material and live cultures of S. typhi are at increased risk of acquiring infection. Socio-economic factors : It is a disease of poverty as it is often associated with inadequate sanitation facilities and unsafe water supplies.
Environmental factors : Though the cases are observed through out the year, the peak incidence of typhoid fever is reported during July - September. This period coincides with the rainy season and a substantial increase in fly population.Social factors : pollution of drinking water supplies, open air defecation, and urination, low standards of food and personal hygiene, and health ignorance.
Nutritional status :Malnutrition may enhance the susceptibility to typhoid fever by altering the intestinal flora or other host defences.Incubation period : Usually 10-14 days but it may be as short as 3 days or as long as 21 days depending upon the dose of the inoculums.Reservoir of infection : Man is the only known reservoir of infection - cases or carriers. Period of communicability: A case is infectious as long as the bacilli appear in stool or urine.
Mode of transmission : The disease is transmitted by faeco - oral route or urine oral routes either directly through hands soiled with faeces or urine of cases or carriers or indirectly by ingestion of contaminated water, milk, food, or through flies. Contaminated ice, ice-creams, and milk products are a rich source of infection.
Carriers may be temporary or chronic. Temporary (convalescent or incubatory) carriers usually excrete bacilli up to 6-8 weeks. By the end of one year, 3-4 per cent of cases continue to excrete typhoid bacilli. Persons who excrete the bacilli for more than a year after a clinical attack are called chronic carriers.
Salmonella typhi infecting the body via the Peyer's patches of the small intestine. The bacteria migrates to mesenteric lymph nodes and arrive via the blood in the liver and spleen during the first exposure. After multiple replication in the above locations, the bacteria Migrates back into the Peyer's patches of the small intestine for the secondary exposure and consequently the clinical symptoms are seen. Inflammation in the small intestine leads to ulcers and necrosis.
First week: The disease classically presents with step-ladder fashion rise in temperature (40 - 41C) over 4 to 5 days, accompanied by headache, vague abdominal pain, and constipation. Second week: Between the 7 th -10 th day of illness, mild hepato-splenomegally occurs in majority of patients. Relative bradycardia may occur and rose-spots may be seen.
Third week: The patient will appear in the "typhoid state" which is a state of prolonged apathy, toxaemia, delirium, disorientation and/or coma. Diarrhoea will then become apparent. If left untreated by this time, there is a high risk (5-10%) of intestinal hemorrhage and perforation.Rare complications: Typhoid hepatitis,Emphyema, Osteomyelitis, and Psychosis.
2-5% patients may become Gall-bladder carriers
Typhoid should be considered in any patient with prolonged unexplained fever in endemic areas and in those with a history of recent travel to endemic area. Prolonged fever, rose spots, relative bradycardia and leucopenia make typhoid strongly suggestive. Widal test measures titres of serum agglutinins against somatic (O) and flagellar (H) antigens which usually begin to appear during the 2nd week. In the absence of recent immunization, a high titre of antibody to O antigen > 1:640 is suggestive but not specific.
Polymerase chain reaction (PCR) can be performed on peripheral mononuclear cells. The test is more sensitive than blood culture alone (92% compared with 50-70%) but requires significant technical expertise Blood cultures are positive in 70-80% of cases during the 1st week. Stool and urine cultures are usually positive (45-75%) during the 2nd-3rd week. Bone marrow aspirate cultures give the best confirmation (85-95%) The tracing of carriers in cities by sewer swab technique
RAPID TESTS FOR DIAGNOSING TYPHOIDTyphidot test that detects presence of IgM and IgG in one hour (sensitivity>95%, Specificity 75%)
Typhidot-M, that detects IgM only (sensitivity 90% and specificity 93%)
Typhidot rapid (sensitivity 85% and Specificity 99%) is a rapid 15 minute immunochromatographic test to detect IgM. IgM dipstick test
Wilson and Blair bismuth sulphite medium jet black colony with a metallic sheen
Management of typhoid fever: General: Supportive care includesMaintenance of adequate hydration. Antipyretics. Appropriate nutrition.Specific: Antimicrobial therapy is the mainstay treatment. Selection of antibiotic should be based on its efficacy, availability and cost. Chloramphenicol , Ampicillin ,Amoxicillin , Trimethoprim &am