Typhoid KingdomEubacteria PhylumProteobacteria ClassGammaproteobact eria OrderEnterobacteriales FamilyEnterobacteriaceae GenusSalmonella SpeciesS. enterica Subspecies Salmonella enterica enterica Salmonella enterica salamae Salmonella enterica arizonae Salmonella enterica diarizonae Salmonella enterica houtenae Salmonella enterica indica Rod Shaped flagellated Facultative anaerobic Gram –ve short bacillus Growing temp C/ F S. enterica Typhimurium colonies on a Hektoen enteric agar plate Gastric Fever, Abdominal fever Infantile Fever Slow Fever Nervous Fever Pythogenic Fever Mary Mallon “Typhoid Mary “ worked as a cook in New York City in the early 1900s. Public health pioneer Sara Josephine Baker, MD, PhD tracked her down after discovering that she was the common link among many People who had become ill from typhoid fever. She was traced to typhoid Outbreaks a second time so she was put in prison again where she lived until she died

Incidence of typhoid fever ♦ Strongly endemic ♦ Endemic ♦ Sporadic cases Epidemiology With an estimated 16–33 million cases of annually resulting in 216,000 deaths in endemic areas, the World Health Organization identifies typhoid as a serious public health problem. Its incidence is highest in children and young adults between 5 and 19 years old

Transmission Fecal-oral route Close contact with patients or carriers Contaminated water and food Flies and cockroaches. A schematic diagram of a single Salmonella typhi cell showing the locations of the H (flagellar), 0 (somatic), and Vi (K envelope) antigens. Antigenic structure of Salmonella  Somatic /O antigen  Flagellar /H antigen United States Centers for Disease Control and Prevention (CDC), the chlorination of drinking water has led to dramatic decreases in the transmission of typhoid fever in the U.S

Pathogenesis S.Typhi. Lower ileum peyer's patches & mesenteric lymph nodes thoracic duct 1st bacteremia (Incubation stage) 10-14d mononuclear phagocytes ( mononuclear phagocytes ) 2nd bacteremia liver 、 spleen 、 gall 、 BM,ect early stage acme stage (1-3W ） LN Proliferate,swell necrosis defervescence stage （ 3-4w ） Bac. In gall Bac. In feces S.Typhi eliminated convalvescence stage (4-5w) Enterorrhagia,i ntestinal perforation

Gastrointestinal tract host-pathogen interactions. The amount of bacilli infection (>10 5 bacteria). ingested orally  Stomach barrier (some Eliminated)  Enters the small intestine  Penetrate the mucus layer  Enter mononuclear phagocytes of ileal peyer's patches and mesenteric lymph nodes  Proliferate in mononuclear phagocytes spread to blood. initial bacteremia (Incubation period).  Enter spleen, liver and bone marrow (reticulo-endothelial system) further proliferation occurs  A lot of bacteria enter blood again. (second bacteremia).  Recovery

The course of untreated typhoid fever is divided into four individual stages Hyperplasia stage(1 st week): Swelling lymphoid tissue and proliferation of macrophages. Bradicardia, Malaise, Epistaxis, Leukopenia Widal test- Negative Necrosis stage(2 nd week): Necrosis of swelling lymph nodes or solitary follicles(Delirium), Rhonchi, Hepatomegaly. 3 rd weeks : Intestinal hemorrhage, encephalitis, Metasatatic abscesses, Neuropsychiatric symptoms 4 th and final weeks : Delirious, defervescence, convalescence

Diagnosis Diagnosis is made by any, bone marrow or stool cultures and with the Widal test (demonstrationbone marrowstoolculturesWidal test of salmonella antibodies against antigens O-somatic and H-flagellar). In epidemics and lessantibodiesantigensO-somaticH-flagellarepidemics wealthy countries, after excluding malaria, dysentery or pneumonia, a therapeutic trial time withmalariadysenterypneumonia chloramphenicol is generally undertaken while awaiting the results of Widal test and cultureschloramphenicolWidal test of the blood and stool. The Widal test is time consuming and oftentimes when diagnosis is reached it is too late to startWidal test an antibiotic regimen. The term "enteric fever" is a collective term that refers to typhoid andantibiotic paratyphoid

The rediscovery of oral rehydration therapy in the 1960s provided a simple way to prevent many of the deaths of diarrheal diseases in general.oral rehydration therapy Where resistance is uncommon, the treatment of choice is a fluoroquinolone such as ciprofloxacin otherwise, a third-generation cephalosporin such as ceftriaxone or cefotaxime is the first choice.Cefixime is a suitable oral alternative.ciprofloxacinceftriaxonecefotaxime Typhoid fever in most cases is not fatal. Antibiotics, such as ampicillin, chloramphenicol, trimethoprim- sulfamethoxazole, Amoxicillin andciprofloxacin, have been commonly used to treat typhoid fever in developed countries.Antibioticsampicillinchloramphenicoltrimethoprim- sulfamethoxazoleAmoxicillinciprofloxacin Prompt treatment of the disease with antibiotics reduces the case-fatality rate to approximately 1%. When untreated, typhoid fever persists for three weeks to a month. Death occurs in between 10% and 30% of untreated cases. In some communities, however, case-fatality rates may reach as high as 47%. Treatment

There are two vaccines currently recommended by the World Health Organization for the prevention of typhoid:World Health Organization  The live, oral Ty21a vaccine (sold as Vivotif Berna)  The injectable Typhoid polysaccharide vaccine (sold as Typhim Vi by Sanofi Pasteur and Typherix by GlaxoSmithKline). Prevention