Typhoid Fever
Typhoid fever is a disease caused by the gram-negative bacterium Salmonella
enterica serotype Typhi (S. Typhi). Symptoms includes high
fever, prostration, abdominal pain, and a rose-colored rash. This disease can
be Diagnosed by is by culture. Treatment is with ceftriaxone, ciprofloxacin,
or azithromycin.
Transmission of typhoid fever
Humans are
the only natural host and reservoir. Typhoid bacilli are shed in stool of
asymptomatic carriers or in stool or urine of people with active disease. The
infection is transmitted by ingestion of contaminated food or water contaminated with feces.
Inadequate hygiene after defecation may spread S. Typhi to
community food or water supplies. In endemic areas where sanitary measures are
generally inadequate, S. Typhi is transmitted more frequently
by water than by food. In areas where sanitary measures are generally adequate,
transmission is chiefly by food that has been contaminated during preparation
by healthy carriers. Flies may spread the organism from feces to food.
Occasional
transmission by direct contact (fecal-oral route) may occur in children during
play and in adults during sexual practices. Rarely, hospital personnel who have
not taken adequate enteric precautions have acquired the disease when changing
soiled bedclothes.
The
organism enters the body via the gastrointestinal tract and gains access to the
bloodstream via the lymphatic channels. Ingestion of large numbers of S. Typhi
is necessary to overcome gastric acidity. Low gastric acidity, which is common
among older people and among people who use acid-suppressing drugs, can
markedly decrease the infective dose. Intestinal ulceration, hemorrhage, and
perforation may occur in severe cases.
Salmonella carrier state
Occasionally there is carrier state of salmonella to human being. And the
state of carrier remain for the patients who remain treatment
About 3%
of untreated patients, referred to as chronic enteric carriers, harbor
organisms in their gallbladder and shed them in stool for > 1
year. Some carriers have no history of clinical illness. Most of the estimated
2000 carriers in the US are older women with chronic biliary disease.
Obstructive uropathy related to schistosomiasis or nephrolithiasis
may predispose certain typhoid patients to urinary carriage.
Epidemiologic
data indicate that typhoid carriers are more likely than the general population
to develop hepatobiliary cancer. read more...
Symptoms and Signs of Typhoid Fever
For
typhoid fever, the incubation period (usually 8 to 14 days) is inversely
related to the number of organisms ingested. Onset is usually gradual, with
fever, headache, arthralgia, pharyngitis, constipation, anorexia, and abdominal
pain and tenderness. Less common symptoms include dysuria, nonproductive cough,
and epistaxis.
Without
treatment, the temperature rises in steps over 2 to 3 days, remains elevated
(usually 39.4 to 40° C) for another 10 to 14 days, begins to fall
gradually at the end of the 3rd week, and reaches normal levels during the 4th
week. Prolonged fever is often accompanied by relative bradycardia and
prostration. Central nervous system symptoms such as delirium, stupor, or coma
occur in severe cases. In about 10 to 20% of patients, discrete, pink,
blanching lesions (rose spots) appear in crops on the chest and abdomen during
the 2nd week and resolve in 2 to 5 days.
Splenomegaly,
leukopenia, anemia, liver function abnormalities, proteinuria, and a mild
consumption coagulopathy are common. Acute cholecystitis and hepatitis may
occur.
Typhoid
Fever (Rose Spots)
During
the second week of infection about 10 to 20% of patients develop rose spots
symptoms. Which are discrete, pink,blanching lesions,arrows.this signs appear
in crops on the chest and around abdomen.
Late in the disease, when intestinal
lesions are most prominent, florid diarrhea may occur, and the stool may
contain blood (occult in 20% of patients, gross in 10%). In about 2% of
patients, severe bleeding occurs during the 3rd week, with a case fatality rate
of about 25%. An acute abdomen and leukocytosis during the 3rd week may suggest
intestinal perforation, which usually involves the distal ileum and occurs in 1
to 2% of patients.
Pneumonia may develop during the 2nd or 3rd
week and may be due to secondary pneumococcal infection, although S. Typhi
itself can also cause pneumonia. Bacteremia occasionally leads to focal
infections such as osteomyelitis, endocarditis, meningitis, soft-tissue
abscesses, glomerulitis, or genitourinary tract involvement.
Atypical
presentations of typhoid fever, such as pneumonitis, fever only, or, very
rarely, symptoms consistent with urinary tract infection, may delay diagnosis.
Diagnosis of Typhoid Fever
- Cultures
Other
infections causing a similar presentation to that of typhoid fever
include other Salmonella infections, the major rickettsioses, leptospirosis, disseminated
tuberculosis, malaria, brucellosis, tularemia, infectious
hepatitis, psittacosis, Yersinia enterocolitica infection, and lymphoma.
Cultures
of blood, stool, and urine should be obtained. Because drug resistance is
common, standard susceptibility testing is essential. The nalidixic acid
susceptibility screening test is no longer recommended because it no longer
reliably predicts susceptibility to ciprofloxacin. Blood cultures are
usually positive only during the first 2 weeks of illness, but stool cultures
are usually positive during the 3rd to 5th weeks. If these cultures are
negative and typhoid fever is strongly suspected, culture from a bone marrow
biopsy specimen may reveal the organism.
Typhoid
bacilli contain antigens O and H that stimulate the host to form corresponding
antibodies. A 4-fold rise in O and H antibody titers in paired specimens
obtained 2 weeks apart suggests S. Typhi infection (Widal
test). However, this test is only moderately (70%) sensitive and lacks
specificity; many nontyphoidal Salmonella strains cross-react,
and liver cirrhosis causes false-positives.
Prognosis for Typhoid Fever
Without
antibiotics, the case fatality rate is about 12%. With prompt therapy, the case
fatality rate is 1%. Most deaths occur in malnourished people, infants, and
older people.
Stupor,
coma, or shock reflects severe disease and a poor prognosis.
Complications
occur mainly in patients who are untreated or in whom treatment is delayed.
Treatment of Typhoid Fever
- Ceftriaxone
- Sometimes a fluoroquinolone
or azithromycin
Antibiotic
resistance is common and increasing, particularly in endemic areas, so
susceptibility testing should guide drug selection.
Prevention of Typhoid Fever
·
Drinking
water should be purified, and sewage should be disposed of effectively.
·
Chronic
carriers should avoid handling food and should not provide care for patients or
young children until they are proved free of the organism; adequate patient isolation
precautions should be implemented. Special attention to enteric precautions is
important.
·
Travelers
in endemic areas should avoid ingesting raw leafy vegetables, other foods
stored or served at room temperature, and untreated water (including ice cubes).
Unless water is known to be safe, it should be boiled or chlorinated before
drinking.
Vaccination
A
live-attenuated oral typhoid vaccine is available (Ty21a strain); it is used
for travelers to endemic regions and is about 70% effective. It may also be
considered for household or other close contacts of carriers.
- Typhoid
fever is spread enterically and causes fever and other constitutional
symptoms (eg, headache, arthralgia, anorexia, abdominal pain and
tenderness); later in the disease, some patients develop severe, sometimes
bloody diarrhea and/or a characteristic rash (rose spots).Bacteremia
occasionally causes focal infections (eg, pneumonia, osteomyelitis,
endocarditis, meningitis, soft-tissue abscesses, glomerulitis).A chronic
carrier state develops in about 3% of untreated patients; they harbor
organisms in their gallbladder and shed them in stool for > 1
year.Diagnose using blood and stool cultures; because drug resistance is
common, susceptibility testing is essential.Treat with ceftriaxone, a
fluoroquinolone, or azithromycin, guided by susceptibility testing;
corticosteroids may be given to decrease severe symptoms.Give carriers a
prolonged course of antibiotics; sometimes cholecystectomy is necessary.Patients
must be reported to the local health department and prohibited from
handling food until they are proved free of the organism.Vaccination may
be appropriate for certain travelers to endemic regions.read more.........