dr. Hadeel fadhil FIBMS
TYPHOID FEVER
1- Identification:Systemic bacterial disease characterized by insidious onset of sustained fever, severe headache, malaise, anorexia, a relative bradychardia, splemomegally, rose spots on the trunk in 25% of patients, non-productive cough in early stage of illness & constipation more common than diarrhea in adults.
Many mild & atypical infection may occur.
The case fatality rate of 10-20%
* 15-20% of patients may have relapse (which are generally much milder than the initial clinical illness).
Paratyphoid fever present as similar clinical picture, but tends to be milder, & the case fatality rate is much lower. Relapse may occur in approximately 3-4% of cases.
The etiological organism can be isolated from the blood early in the disease & from urine & feces after the first week, bone marrow culture provide the best bacteriological confirmation, serological test(widal test) are generally of little diagnostic value.
2- Infectious agent:
For TF , Salmonella typhi,
For Para typhoid fever, 3 serovars of salmonella enterica are recognized: S. paratyphi A, B&C.
3- Occurrence:
World wide, the annual incidence of typhoid fever is about 17 million cases with approximately 600000 death.
4- Reservoir:
Human for both TF & PTF, rarely domestic animals for PTF.
Family contact may be transient or permanent carrier. Short term fecal carriers are more common than urinary carrier. The carrier State may follow acute illness or mild or even sub clinical infections.
The chronic carrier state is most common among persons infected during middle age, especially women.
5- Mode of tranismission:
**food & water contaminated
by feces & urine of patients
& carries.
**raw fruits, vegetables.
**contaminated milk & milk products.
**flies may infect the food in which the organism then multiplies to achieve an infective dose.
** important vehicles in some countries include shellfish taken from sewage contaminated beds ( particularly oysters ) .
6- Incubation period:
Depends on the size of the infecting dose, from 3 days to 1 month with usual range 8-14 days. In paratyphoid fever , the incubation period range from 1 to 10 days .
7- Period of communicability:
As long as the bacilli appear in excreta, usually from the 1st week throughout convalescence, variable thereafter (commonly 1-2 week for paratyphoid ) .
About 10% of untreated typhoid fever patient will discharge bacilli for 3 month after onset of symptoms, 2-5 % become permanent carrier fewer patients infected with paratyphoid fever organism may become permanent gallbladder carriers.
8- Susceptibility & resistance:
Susceptibility is general,
& is increased in individual with gastric achlorhydria, HIV positive. In endemic area, typhoid fever is most common in preschool & children 5-19 years of age.
Enviromental factors : reported through out the year. Peak incidence from July – September . closely linked to sanitation.
9- Methods of control:
A- Preventive methods:
1- health education to public regarding
the importance of hand washing after defecation
& before eating or serving & carrying food for food handler & attendants.
2- dispose of human feces in a sanitary matter & maintain fly proof latrines
3- protect, purify & chlorinate public water supply.
4- control flies by screening, spraying with insecticide & use of insecticidal baits & traps
5- cleanliness in food preparation & handling, refrigerate as appropriate. Particular attention should be directed to the proper storage of salads & other foods served cold.
6- pasteurize or boil all milk & diary products.
7- enforced suitable quality-control procedures in industries that prepare food & drink for human consumption.
8- instrict patients , convalescents & carriers in personal hygiene & hand washing as a routine practice after defecation & before preparing & serving food.
9- encourage breast feeding throughout infancy , boil all milk & water used for infant feeding.
10- exclude typhoid carriers from handling food & from providing patient care. Chronic carriers should not be released from supervision & restriction of occupation until local or state regulation are met , often not until 3 consecutive negative culture from stool at least 1 month apart & at lest 48 hours after antimicrobial therapy has stopped.
11- typhoid fever : immunization
for occupational exposure, travel to endemic area, living in area of high endemisity & household member of
Documented S . typhi carrier and microbiology labrotory personnel who frequently work with S . typhi .
An oral, live vaccine using salmonella typhi strain Ty 21a , live attenuated S . typhi (requiring 3 doses, 2 days apart , able to produce a 66 % protection rate lasting for 2 years ..
A paranteral vaccine containing the polysaccharide Vi antigen (single dose) it give about 90% protection for 5 years.not give for children younger than 1 year . booster doses are desirable for those at continuing risk for infection with an interval range from 2-5 years, depending on the type of vaccine.
PTF : oral typhoid vaccine (Ty 21a) conferred partial protection against paratyphoid
B- control of patient, contact & the immediate environment:
1- report to local health authority: obligatory.
2- isolation: enteric precaution while ill, hospital care is desirable during acute illness. release from supervision by local health authority should be after 3 consecutive negative cultures of feces taken at least 24 hours apart & at least 48 hours after any antimicrobial, & not earlier than 1 month after onset, if any one of theses is positive, repeat culture at interval of one month during the 12 month following onset until at least 3 consecutive negative culture is obtained.
3- concurrent disinfection:
of feces & urine, adequate sewage disposal system.
Terminal cleaning
4- quarantine: none.
5-Immunization of contacts : routine administration of typhoid vaccine is of limited value for family, household &nursing contacts who have been or may be exposed to active cases, it should be considered for those who may be exposed to carriers . there is no effective immunization for paratyphoid A fever .
6- Investigation of contacts & source of infection : search for unreported cases , carriers or contaminated food , water , milk ,shellfish .
Household and close contacts should not be employed in sensitive occupation (e.g., food handlers ) until at least 2 –ive feces and urine cultures , taken at least 24 hr apart, are obtained .
7- specific treatment: the goals of pharmacotherapy are to eradicate the infection , reduce morbidity , and prevent complication , oral ciprofloxacin should be considered the drug of choice , chloramphenicol , amoxicillin, TMP-SMX ( particularly in children) have high efficacybfor acute infection . patient with concurrent schistosomiasis must be also treated with praziquantel to eliminate possible carriage of S. Typhi bacilli by schistosome .