Enteric fever/typhoid and paratyphoid Flashcards
What is typhoid fever?
Systemic illness caused by salmonella typhy and paratyphi A,B and C causing septicaemia
When dose non typhoidal enteric fever occur
Immunocompromised or super imposed infection in chidlren with zoontoci salmonella
Endemic regions typhoid
India/south east asia
Sub saharan africa
Central/south america
WHo is typhoid most common in in endemic areas
Children and young adults
Causative organsims of salmonella
S.typhi
S.paratyphi A+B
Paratyphi C
How is typhoid spread
Faeco-oral - water and food
Or close contact with people or patients or carriers asypmtomatic
Insects and flies - contaminating foods
What strain of typhoid vomitting and diarrhoea before other symptoms and more predominant
Paratyphoid A+B - already multiplied in food
Which salmonella strain causes septicaemia and abscesses without gut involvement
Paratyphoid C
Antigens from salmonella general vs typhi
3 antigens
All salmonella - Smoatic - O antigen
Flagella - H antigen
Typhi and paratyphi also have Vi (coats O antigen)
What factor about contraction of typhoid effects severity of disease
Dose -related
Higher dose = more severe, shorter incubation period
Why do PPIs and H2 antagonists increase the risk of enteric infection
Lower stomach acidity - lower level of salmonella typhi needed to contract typhoid
What are the most important reservoirs for infection
Asymptomatic, convalescent or chronic human carriers eg food handlers
Pathology of enteric fever
Salmonella typhi -> Small intestine -> lymphatics -> mesenteric lymph nodes -> thoracic duct -> blood stream -> gall bladder, spleen, bone marrow, liver
Multiply inside macrophages at these sites
Re-enter blood stream -> symptoms
How is the bowel affected in enteric fever
Baceria collect in peyers patches and other intestinal lymph follicles
Strong inflam response -> hyperplasia, necrosis and ulceration after 7-10 days
Complications of gut inflammation in typhoid
Blood vessel involvement - bleeding
Perforation
Where do typhoid nodules occur
Initially liver, spleen, bone marrow and lymph
Diffuse -> Myocardium, kidney, lung
Abscess formation - bone, brain, liver, spleen
What are typhoid nodules
Aggregated infected macrophages with salmonella typhi
When does fever classically return to normal in typhoid
3 weeks
Fatal complications of eneteric fever
Perforation
Haemodynamic shock ass w intestinal haemorrhage or severe toxicaemia
Meningitis
Average incubation period of typhoid
14 dyas
Can be <7 days to 3 weeks
Fever features in typhoid
Sustained through illness
Increases gradually in first week - evening rise
High or sustained fever of 39-40 degrees C progresses in 3rd and 4th week
Symptoms of typhoid
Malaise, aches and pains, anorexia
Abdominal pain or discomfort, diarrhoea, headache, constipation, non productive cough
Stage 1 and 2 typhoid symptoms
slowly rising - stepladder temp 4-5 days
Abdo pain and myalgia
Malasia
Headache
Constipation
Relative bradycardia
Stage 2 - progression of these in 2nd week
End of 1st week signs of typhoid
Rose spots on upper abdomen and back
Cough
Splenomegaly
Abdo distension w tenderness
Diarrhoea
