1. Typhoid and Paratyphoid Fever
Eman Adnan Al-kaseer

2. 1.Identification: A systemic bacterial disease with insidious onset of sustained fever, marked headache , malaise , anorexia, relative bradycardia, spleenomegaly, nonproductive cough in the early stage of the illness, rose spots on the trunk in 25% of white- skinned patients and constipation more often than diarrhea in adults. The clinical picture varies from mild illness with low grade fever to sever clinical disease with abdominal discomfort and multiple complications.

3. Unapparent or mild illnesses occur , especially in endemic areas ; 60% - 90% of patients with typhoid fever do not receive medical attention or are treated as outpatients. Mild cases show no systemic involvement ; the clinical picture is that of gastroenteritis. Non sweating fevers ,mental dullness , slight deafness and parotitis may occur. Payer patches in the ileum can ulcerate , with intestinal hemorrhage or perforation (about 1% of cases), especially late in untreated cases. Sever cases with altered mental status have been associated with high case fatality rates.

4. 2.Infectious agent : salmonella typhi for typhoid fever and salmonella paratyphi A,B and C in rare cases. 3.Occurrence: worldwide. Most of the burden of the disease occurs in the developing world. Most cases in the industrialized world are acquired during travel in endemic areas. Paratyphoid fever occurs sporadically or in limited outbreaks, probably or in limited outbreaks, probably more frequently than reports suggest. Paratyphi A is more common , B is less frequent and C is rare .

5. 4.Reservoir : humans for both typhoid and paratyphoid ; questionably , domestic animals for paratyphoid. Family contacts may be transient or permanent carriers. A carrier state may follow acute illness or mild or even sub – clinical infections. In most parts of the world , short term fecal carriers are more common than urinary carriers. The chronic carrier state is most common (2%- 5%) among persons infected during middle age, especially women ; carriers frequently have biliary tract abnormalities including gall stones, with S.typhi located in the gallbladder. The chronic urinary carrier state may occur with schistosome infections or kidney stones.

6. 5. Mode of transmission : ingestion of food and water contaminated by feces and urine of patients of carriers. Important vehicles in some countries include shellfish (particularly oysters) from sewage – contaminated beds, raw fruit ,vegetables fertilized by night soil and eaten raw, and contaminated milk/milk products ( usually contaminated through hands of carriers). Flies may infect foods in which the organism then multiplies to infective doses (those are reportedly lower for typhoid than for paratyphoid bacteria).waterborne transmission of S.typhi usually involves small inocula, food – borne transmission is associated with large inocula and high attack rates over short periods. Sexual transmission of typhoid fever from an asymptomatic carrier has been documented .

7. 6.Incubation period : depends on inoculum size and on host factors ; from 3 days to over 60 days, usual range 8 – 14 days; the incubation period for paratyphoid fever is 1 – 10 days. 7. Period of communicability : as long as bacilli appear in excreta, usually from the first week throughout convalescence ; variable thereafter (commonly 1 -2 weeks for paratyphoid). About 10% of untreated typhoid fever patients discharge bacilli for 3 months after onset of symptoms ; 2% - 5% become permanent carriers. Fewer persons infected with paratyphoid organisms may become permanent gallbladder carriers.

8. 8. Susceptibility : it is general and is increased in individuals with gastric achlorhydria. One study has suggested that susceptibility may be increased in persons who are HIV – positive.
9.Methods of control :
Preventive measures : it is based on access to safe water and proper sanitation , as well as adherence to safe food – handling practices
1) Educate the public regarding the importance of hand – washing .

9. 2)Dispose of human feces safely , and maintain fly – proof latrines
2)Dispose of human feces safely , and maintain fly – proof latrines. 3)Protect , purify and chlorinate public water supplies, and avoid possible backflow connections between water and sewer systems. 4)Control flies by screening and use of insecticidal baits and traps or when appropriate , spraying with insecticides. Control fly- breeding through frequent garbage collection and disposal , and through fly control measures in latrine construction and maintenance. 5)Use scrupulous cleanliness in food preparation and handling ; refrigerate as appropriate. Pay particular attention to the storage of salads and other foods served cold. These provisions apply to home and public eating – places . 6)Pasteurize or boil all milk and dairy products. Supervise the sanitary aspects of commercial milk production , storage and delivery. 7)Limit the collection and marketing of shellfish to supplies from approved sources.

10. 8)Instruct the community , patients , convalescents and carriers in personal hygiene. Emphasize hand washing as a routine practice after defecation and before preparing , serving or eating food. 9)Encourage breast feeding throughout infancy ; boil all milk and water used for infant feeding . 10)Typhoid carriers should be excluded from handling food and from providing patient care . Identify and supervise typhoid carriers ; culture of sewage may help in locating them . Chronic carriers should not be released from supervision and restriction of occupation until local or state regulations are met , often not until 3 consecutive negative cultures are obtained from fecal specimens (and urine in areas endemic for schistosomiasis), at least 1 month apart and at least 48 hours after antimicrobial therapy has stopped . Administration of 750 mg of ciprofloxacin or 400 mg of norfloxacin twice daily for 28 days provides successful treatment of carriers in 80 – 90% of cases.

11. 11) Immunization for typhoid fever is not routinely recommended in non endemic areas except for those subject to unusual occupational exposure to enteric infections (e.g. clinical microbiology technicians) and household members of known carriers. WHO recommends vaccination for people who travel to endemic high risk areas and school age children living in endemic areas where typhoid fever control is a priority. Vaccination of high risk populations is considered the most promising strategy for the control of typhoid fever . No vaccine for paratyphoid fever are currently available.

12. An oral , live vaccine using S
An oral , live vaccine using S.typhi strain ty21a (requiring 3 or 4 doses , 2 days apart ) and a parentral vaccine containing the single dose polysaccharide Vi antigen are available ; these are as protective as whole cell bacteria vaccine and much less reactogenic.booster doses every 2 to 5 years , according to vaccine type , are desirable for those at continuing risk of infection . Ty21a vaccine is only licened for children 6 years old and older in the US, but for younger children in other countries.

13. B. Control of patient , contact and the immediate environment: 1)Report to local health authority 2)Isolation :enteric precautions while ill ; hospital care is desirable during acute illness. Release from supervision by local health authority based on not fewer than 3 consecutive negative cultures of feces ( and urine in patients with schistosomiasis) at least 24 hours apart , at least 48 hours after any antimicrobials, and not earlier than 1 month after onset . If any of these is positive , repeat cultures at monthly intervals during the 12 months following onset until at least 3 consecutive negative cultures are obtained.

14. 3)Concurrent disinfection : of feces , urine and articles soiled therewith. 4)Quarantine :not applicable 5)Immunization of contacts: routine administration of typhoid vaccine is of limited value for family, household and nursing contacts who have been or may be exposed to active cases; it should be considered for those who may be exposed to carriers for prolonged basis. There is no effective immunization for paratyphoid fever.

15. 6)Investigation of contacts and source of infection
6)Investigation of contacts and source of infection . 7)Specific treatment: Evidence suggests that fluoroquinolones are the drug of choice in adults. However , recent emergence of decreased susceptibility , and frank resistance to fluoroquinolones in both S.typhi and paratyphi A, restricts widespread use in primary care facilities and mandates antimicrobial testing of all isolates. If local strains are known to be sensitive to traditional first line antibiotics , oral chloramphenicol , amoxicillin or trimethoprim(particularly in children) should be used in accordance with local antimicrobial sensitivity patterns.

16. Ceftriaxone , a parenteral once daily antibiotic, is useful in patients with complications such that oral antibiotics cannot be used. Short term , high dose corticosteroid treatment ,combined with specific antibiotics and supportive care, reduces mortality in critically ill patients. Patients with concurrent schistomiasis must also be treated with praziquantel to eliminate possible carriage of S.typhi.

17. c. Epidemic measures : 1)Search intensively for the case /carrier who is the source of infection , and for the vehicle (water or food) through which infection was transmitted . 2)Selectively eliminate suspected contaminated food. Pasteurize or boil milk , or exclude milk supplies and other foods suspected on epidemiological evidence until safety is ensured. 3)Chlorinate suspected water supplies .all drinking water must be chlorinated , treated with iodine , or boiled before use. 4)Use of vaccine should be considered before or during an outbreak ; a protective efficacy of over 70% was recently obtained among immunized school age children during an outbreak in china. D)Disaster implications: with disruption of usual water supply and sewage disposal and of controls on food and water , transmission and large scale outbreaks of typhoid fever may occur if there are active cases or carriers in a displaced population .

18. E.International measures : For typhoid fever ; immunization is advised for international travelers to endemic areas , especially if travel is likely to involve exposure to unsafe food and water. Immunization is not a legal requirement for entry into a country.