Typhoid Fever 3

8/9/2019 Typhoid Fever 3

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TYPHOID

FEVER


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What is typhoid fever?

* Typhoid fever is a bacterial infection of theintestinal tract and occasionally the

bloodstream.

* The disease rarely occurs in developedcountries. It is most commonly seen in

countries with poor sanitary conditions andcontaminated water supplies.


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Outbreaks are rare.

The germ that causes typhoid is a uniquehuman strain of Salmonella called Salmonella

typhi.


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4

1.Salmonella typhi (Typhoid fever)

Most common and more severe form

2. Salmonella paratyphi (Paratyphoid fever)

Much more mild than Typhoid fever


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How does the bacteria cause

disease? After the ingestion of contaminated food or water,

the Salmonella bacteria invade the small intestineand enter the bloodstream temporarily. Thebacteria are carried by white blood cells in the liver,

spleen, and bone marrow. The bacteria thenmultiply in the cells of these organs and reenter thebloodstream. Patients develop symptoms, includingfever, when the organism reenters the bloodstream.Bacteria invade the gallbladder, biliary system, andthe lymphatic tissue of the bowel. Here, theymultiply in high numbers. The bacteria pass into theintestinal tract and can be identified for diagnosis incultures from the stool tested in the laboratory.


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Who gets typhoid fever?

Anyone can get typhoid

Occasionally, local cases can be traced toexposure to a person who is a chronic carrier.

Infants and persons over 60 usually have theseverest cases.


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Epidemiology: Incidence

World: 17 million cases per year

U.S.: 400 cases per year (70% in travelers)

while only karachi may have 400 cases everyfew months.


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Incidence of typhoid fever

Strongly endemic

Endemic

Sporadic cases


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Risk factors

Highly dense living conditions


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What are the symptoms?

The symptoms may occur rapidly, particularlyin children.

However, in adults, they usually come on

slowly

Relapses are common.

Symptoms generally appear one to threeweeks after exposure.


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Symptoms Incubation (first 7-14 days after ingestion)

Usually asymptomatic Diarrhea may occur

Active infection

Severe Headache Generalized Abdominal Pain

Anorexia

Constipation more common than Diarrhea

Fever [usually higher in the evening] 103 F-104 F (39 C-40 C).

Intermittent Fever initially

Sustained

Fever to high temperatures later


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Signs

Pulse-Temperature Dissociation(uncommon)

Rose Spots (present in 25% of cases)

Blanching pink macular spots 2-3 mm overtrunk

Complications: (occurs in 10-15% of

cases)

Gastrointestinal Bleeding (2-10% of cases)

Bowel perforation

Typhoid encephalopathy


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Rose spots on the chest of a patient with typhoid

fever due to the bacterium Salmonella typhi.


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For how long can an infected

person carry the typhoid germ? The carrier stage varies from a number of

days to years.

Only about 3% of cases go on to become

lifelong carriers of the germ and

This tends to occur more often in adults than

in children.


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LaboratoryExam

Blood Culture

BestTestSensitivity in first week

Bone Marrow culture

Higher sensitivity than Blood Culture

Fecal culture

Low sensitivity (~33%)

Salmonella serology (Widal's Test)

Poor TestSpecificity

LowTestSensitivity (70%)


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Should infected people be isolated?

Because the germ is passed in the feces of infectedpeople, only people with active diarrhea who areunable to control their bowel habits (infants, certainhandicapped individuals) should be isolated.

Most infected people may return to work or schoolwhen they have recovered, provided that they carefullywash hands after toilet visits.

Food handlers may not return to work until three

consecutive negative stool cultures are confirmed.


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Is there a vaccine for typhoid?

A vaccine is available

but is generally reserved for people traveling

to underdeveloped countries wheresignificant exposure may occur.


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Types of vaccines include:

Ty21ais a live attenuated bacterial vaccinethat protects against typhoid.It is one of twotyphoid vaccines currently recommended bythe World Health Organization.The vaccine

offers between 33 and 78% protection. The vaccine is given by mouth. The vaccine is

presented either as capsules or a liquidsuspension.


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The Vi capsular polysaccharide vaccine(or ViCPS)

The vaccine is only 60 to 80% protective andthe traveller should still be warned to take allusual precautions (careful hygiene, hand

washing and food preparation). The vaccine is injected either under the skin or

into a muscle at least seven days beforetraveling to the typhoid-affected area

(recommend 14 days). The vaccine is noteffective in children under the age of two.

To maintain immunity, the vaccine should berepeated every three years.


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Management: Antibiotics

Specificantibiotics areoftenusedto treatcases of typhoid.

AntibioticResistance is increasing First-Line: Fluoroquinolones

Alternativeantibiotics (resistance is common)

Chloramphenicol Amoxicillin

Trimethoprim-Sulfamethoxazole(Septra)


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Avoid raw vegetables and fruits that cannot be

peeled. Vegetables like lettuce are easily

contaminated and are very hard to wash well. Avoid foods and beverages from street vendors. It is

difficult for food to be kept clean on the street, and

many travelers get sick from food bought from

street vendors. Get vaccinated against typhoid fever.


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Causative Agent: Salmonella typhi

Virulence Factors: S. typhi has a combination

of characteristics that make it an effective

pathogen. This species contains an endotoxin

typical ofGram negative organisms, as well

as the Vi antigen which is thought to increase

virulence. It also produces and excretes a

protein known as invasin that allows non-

phagocytic cells to take up the bacterium,

where it is able to live intracellularly. It is alsoable to inhibit the oxidative burst of

leukocytes, making innate immune response

ineffective.


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DESCRIPTION:

Salmonella typhi

can be very dangerous if not taken care of properly.Not only live in the bloodstream or intestinal tract ofhumans,but is also found in sewage.

Even though most people either die or use antibiotics to

stop the growth of these bacteria, a very smallpercentage of the people who get typhoid fever havecertain antibodies that are able to restrict the growth ofsalmonella typhi and therefore are able to live.

These people plus the people that are cured throughantibiotics are called carriers because even though theywill have no more symptoms of typhoid fever, they willstill have the bacteria inside of them.

Typhoid Fever 3

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