Meaning
Salmonella Paratyphi is a bacterium that causes paratyphoid fever, an enteric fever similar to typhoid but generally less common.
The main human disease-causing types are:
- S. Paratyphi A
- S. Paratyphi B
- S. Paratyphi C
Among these, S. Paratyphi A is particularly important in South Asia.
Transmission
Like S. Typhi, it spreads mainly through the faeco-oral route:
Infected person → Contaminated food/water → New infection
Risk increases with:
- poor sanitation;
- unsafe drinking water;
- inadequate hand hygiene;
- contaminated food handling.
Disease Features
Paratyphoid fever can cause:
- prolonged fever;
- headache;
- weakness;
- abdominal pain;
- diarrhoea or constipation;
- loss of appetite.
Clinically, it can be difficult to distinguish from typhoid without laboratory testing.
Diagnosis
Diagnosis mainly relies on culture-based testing, especially:
- blood culture;
- sometimes bone-marrow culture.
Serological tests have limitations and should not be used alone for confirmation.
Treatment
Paratyphoid is treated with appropriate antibiotics.
However, antimicrobial resistance is increasingly important, with resistance reported to several commonly used drugs.
This makes:
- surveillance;
- culture testing;
- antibiotic stewardship
important for treatment.
S. Paratyphi vs S. Typhi
S. Typhi causes typhoid fever.
S. Paratyphi causes paratyphoid fever.
Both are:
- human-adapted;
- spread mainly through contaminated food and water;
- part of the broader category of enteric fever.
Vaccination Gap
An important distinction is that current Typhoid Conjugate Vaccines (TCVs) protect against S. Typhi, not S. Paratyphi A.
This means paratyphoid can remain a public-health concern even where typhoid vaccination coverage improves.
Why It Matters for India
Paratyphoid is relevant because:
- South Asia carries a significant enteric-fever burden;
- sanitation gaps sustain transmission;
- antimicrobial resistance complicates treatment;
- lack of a widely used licensed vaccine against S. Paratyphi A remains a challenge.
