04_-_Typhoid_Fever

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TYPHOID FEVER :

Enteric fever TYPHOID FEVER

Etiology ::

Etiology : Typhoid fever is caused by a virulent bacterium called Salmonella typhi thriving in conditions of poor sanitation and crowding. G-ve bacilli in family Enterobacteriaceae Antigens: located in the cell capsule H (flagellar antigen). Vi (polysaccharide virulence Ag). O (Somatic Ag) “

Transmission:

Transmission S typhi has no nonhuman vectors. via food handled by an individual who chronically sheds the bacteria through stool or, less commonly, urine Hand-to-mouth transmission after using a contaminated toilet and neglecting hand hygiene Oral transmission via sewage-contaminated water or shellfish

Epidemiology:

Epidemiology Typhoid fever occurs worldwide, primarily in developing nations whose sanitary conditions are poor. Typhoid fever is endemic in Asia, Africa, Latin America, the Caribbean, and Oceania. Typhoid fever infects roughly 21.6 million people and kills an estimated 200,000 people every year.

Risk factors:

Risk factors Worldwide, children are at greatest risk of getting the disease Work in or travel to endemic area Have close contact with someone who is infected or has recently been infected with typhoid fever Weak immune system such as use of corticosteroids or diseases such as HIV/AIDS Drinking water contaminated by sewage that contains S. typhi

Pathogenesis:

Pathogenesis The organisms penetrate ileal mucosa reach mesentric lymph nodes via Lymphatics , Multiply, Invade Blood stream via thoracic duct In 7 – 10 days through blood stream infect Liver, Gall Bladder,, spleen, Kidney, Bone marrow. After multiplication, bacilli pass into blood causing secondary and heavier bacteremia

Pathology:

Pathology Essential lesion: proliferation of RES specific changes in lymphoid tissues and mesenteric lymph nodes. "typhoid nodules“ Most characteristic lesion: ulceration of mucous membrane in the region of the Peyer’s patches of the small intestine

Clinical presentation :

Clinical presentation The incubation period for typhoid fever is 7-14 days (range 3-60 days) If not treated, the symptoms develop over four weeks, with new symptoms appearing each week but with treatment, symptoms should quickly improve .

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Clinical manifestations The initial period (early stage due to bacteremia ) First week: non-specific, insidious onset of fever Fever up to 39-40 0 C in 5-7 days, step-ladder( now seen in < 12%), headache chills, toxic, tired, sore throat, cough, abdominal pain and diarrhea or constipation.

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The fastigium stage second and third weeks. fever reaches a plateau at 39-40. Last 10-14 days . more toxic and anorexic with significant weight loss. The conjunctivae are injected, and the patient is tachypneic with a thready pulse and crackles over the lung bases. Abdominal distension is severe. Some patients experience foul, green-yellow, liquid diarrhea (pea soup diarrhea). The( typhoid state) is characterized by apathy, confusion, and even psychosis. Necrotic Peyer patches may cause bowel perforation and peritonitis. This complication may be masked by corticosteroids. At this point, overwhelming toxemia, myocarditis , or intestinal hemorrhage may cause death.

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Signs and symptoms: relative bradycardia. Splenomegaly, hepatomegaly rash ( rose-spots):30%, maculopapular a faint pale color, slightly raised round or lenticular, fade on pressure 2-4 mm in diameter, less than 10 in No. on the trunk, disappear in 2-3 days.

Rash in Typhoid:

Rash in Typhoid Rose- spots: found in front of chest Appear in crops of upto a dozen at a time

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defervescence stage By the fourth week of infection: If the individual survives , the fever, mental state, and abdominal distension slowly improve over a few days. Intestinal and neurologic complications may still occur. Weight loss and debilitating weakness last months. Some survivors become asymptomatic carriers and have the potential to transmit the bacteria indefinitely convalescence stage the fifth week : disappearance of all symptoms, but can relapse

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Atypical manifestations : Mild infection : very common seen recently symptom and signs are mild good general condition temperature is 38 0 C short period of disease recovery expected in 1~3 weeks seen in early antibiotic users in young children more common easy to misdiagnose

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Persistent infection : disease continue > 5 weeks Ambulatory infection : mild symptoms,early intestinal bleeding or perforation.

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Fulminant infection : rapid onset, severe toxemia and septicemia. High fever, chill, circulatory failure, shock, delirium, coma, myocarditis, bleeding and other complications, DIC.

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In the aged temperature not high, weakness common. More complications. High mortality.

Complications :

Complications

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Complications Intestinal hemorrhage Commonly appear during the second-third week may be mild or severe bleeding often caused by unsuitable food, and diarrhea serious bleeding in about 2~8% clues: sudden drop in temperature, rise in pulse, and signs of shock followed by dark or fresh blood in the stool.

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Intestinal perforation: more serious. Incidence:1-4% Commonly appear during 2nd-3rd week. Take place at the lower end of ileum. Before perforation,abdominal pain or diarrhea,intestinal bleeding . When perforation: ↑ abdominal pain, sweating, drop in temperature, and increase in pulse rate, then rebound tenderness +ve reduce or disappear in the dullness of liver, leukocytosis . Temperature rise when peritonitis appear. free air in abdominal x-ray.

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Toxic hepatitis : common,1-3 weeks hepatomegaly, ALT elevated get better with improvement of disease in 2~3 weeks Toxic myocarditis . seen in 2nd-3rd week, usually severe toxemia. Bronchitis, bronchopneumonia. seen in early stage

Blood cultures in Typhoid fever:

Blood cultures in Typhoid fever In Adults 5-10 ml of Blood is inoculated into 50 – 100 ml of Bile broth ( 0.5 % ). Larger volumes 10-30 ml and clot cultures increase sensitivity Blood culture is positive as follows: 1 st week in 90% 2 nd week in 75% 3 rd week in 60% 4 th week and later in 25%

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Bone marrow culture the most sensitive test even in patients pretreated (up to 5 days) with antibiotics. Urine and stool cultures increase the diagnostic yield positive less frequently stool culture better in 3rd~4th weeks Duodenal string test to culture bile useful for the diagnosis of carriers.

Widal test :

Widal test Serum agglutinins raise abruptly during the 2 nd or 3 rd week, it is +ve by 10 th day, but max. during 18-23 rd day The widal test detects antibodies against O and H antigens Two serum specimens obtained at intervals of 7 – 10 days to read the rise of antibodies . The test is neither sensitive nor specific

TREATMENT:

TREATMENT 1-General : Isolation and rest suitable diet include easy digested food or half-liquid food and drinking more water IV fluid to maintain water and acid-base and electrolyte balance Symptomatic : antipyretic

Drug treatment:

Drug treatment Ciprofloxacin : 15 mg/kg/d for 7 days For quinolone-resistant: azithromycin 10mg/kg/d for 7 days OR ceftriaxone 75mg/kg/d for 10-14 days

steroids:

steroids dexamethasone: initial dose 3 mg/kg by slow i.v. infusion over 30 minutes and after six hours, 1 mg/kg is administered and subsequently repeated at six-hourly intervals on seven further occasions, mortality can be reduced by some 80-90% in high-risk patients (high fever with obtundation and meningeal irritation signs)

Carrier:

Carrier Asymptomatic and have positive stool or rectal swab cultures for S. typhi a year following recovery from acute illness. Treatment: co-trimoxazole 2 tab twice/d for 6 wk, OR ciprofloxacin 750 mg twice/d for 4 wk

Carrier:

Carrier Carriers should be excluded from activities involving food preparation and serving. Food handlers should not resume their duties until they have had three negative stool cultures at least one month apart. Vi Ab is used as a screening technique to identify carriers among food handlers and in outbreak investigations. Vi Abs are very high in chronic S . typhi carriers

Relapse:

Relapse Apparent recovery can be followed by relapse in 5 – 10 % of untreated patient culture +ve of S.typhi after 1-3 wks of defervescence Symptom and signs reappear the bacilli have not been completely removed Some cases relapse more than once On few occasions relapses can be severe and may be fatal.

:

Prognosis: Case fatality 0.5-1%. but high in old ages, infant, and serious complications immunity long lasting About 3% of patients become fecal carriers .

Vaccines for Typhoid Prevention:

Vaccines for Typhoid Prevention Two types : 1. Oral – A live vaccine ( typhoral ) One capsule given orally taken before food, with a glass of water or milk, on day 1, 3, 5 ( three doses ) No antibiotics should be taken during the period of administration of vaccine 2. The injectable vaccine, ( typhim –vi) Given as single sc or im injection

Vaccines for Typhoid:

Vaccines for Typhoid Both vaccines are given to only children > 5 years of age. Immunity lasts for 3 years Need a booster Vaccines are not effective in prevention of Paratyphoid fevers

Paratyphoid fever :

Paratyphoid fever It is similar in its symptoms to typhoid fever, but tends to be milder, with a lower fatality rate. It is caused by Paratyphi A, B, and C Rash may be more abundant May present as gastroenteritis specially in children

Prophylaxis :

Prophylaxis

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