Typhoid and Paratyphoid Fever
Eman Adnan Al-kaseer
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.
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.
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 more
frequently than reports suggest.
Paratyphi A is more common , B is less frequent and C
is rare .
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.
5. Mode of transmission : ingestion of food and water
contaminated by feces and urine of patients or 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 .
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. 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 :
A. 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 .
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)L imit the collection and marketing of shellfish to supplies from
approved sources.
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 1month 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) 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.
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.
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 1month 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.
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.
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.
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.
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 .
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.