☕ Typhoid & Blood Tests — Easy Guide for Indian Medical Students

1. What is Typhoid?

Typhoid fever is caused by Salmonella Typhi bacteria.
It spreads mainly through contaminated food & water (remember: ganda pani = bimari ka nirmaata 😄).

2. When to Suspect Typhoid

• Fever for more than 5–7 days (often rising slowly)

• Headache, weakness

• Stomach discomfort, constipation in early stage, loose motions later

• Sometimes rose spots on chest

• Fever with slow pulse (relative bradycardia)

3. Important Blood Tests

CBC (Complete Blood Count)

• WBC count: Often low (leucopenia)

• Relative lymphocytosis after 1st week

• Platelets: Usually normal or slightly low

• Hemoglobin: May drop if illness is long

💡 Tip: Most bacterial infections give high WBC, but typhoid gives low WBC — this helps you suspect it.

Blood Culture 🥇 (Best test in first week)

• Take before giving antibiotics

• Highest chance to catch bacteria in week 1

• After 1 week, chances reduce

Widal Test

• Checks antibodies against O and H antigens

• Useful after 7 days of fever

• O antigen → current infection

• H antigen → past infection or vaccination

• In endemic areas (like India), a rising titer in paired samples is more reliable than one reading

Other Helpful Tests

• ESR: High

• LFT: Mildly raised SGPT/SGOT

• CRP: Mild–moderate rise

• Bone marrow culture: Very sensitive, even after antibiotics

4. Timeline Memory Trick

Week 1: Blood culture catches the thief 🕵️‍♂️
Week 2: Widal test finds the “wanted posters” (antibodies) 📜
Week 3: Bone marrow culture finds the thief hiding underground ⛏️

5. Mini-Case Example

20-year-old with 8 days fever, headache, stomach discomfort

• CBC: WBC 3,200 (low), mild anemia

• Blood culture: Positive for Salmonella Typhi

• Widal: TO 1:160, TH 1:320
  Diagnosis → Typhoid Fever

✅ Quick Revision Table for Exams