Overview
Paratyphoid fever is a bacterial infection caused by Salmonella enterica serotype Paratyphi, closely related to the organism that causes typhoid fever. It produces a similar illness that is generally milder than typhoid, though it can still cause serious complications.
Disease Summary
- Category
- Infectious Disease
- Cause
- Salmonella enterica serotype Paratyphi (A, B, or C)
- Transmission
- Contaminated food or water, spread through the fecal-oral route
- Body System
- Digestive
- Preventable
- Yes
- Curable
- Yes
Symptoms
Common Symptoms
Most people with paratyphoid fever experience one or more of the following symptoms, generally milder than in typhoid fever.
Sustained Fever
Fever that gradually rises over several days and persists.
Headache
Commonly reported alongside fever and general malaise.
Weakness and Fatigue
A general sense of tiredness that develops alongside fever.
Rose-Coloured Spots
Small pink spots may appear on the chest during the first week of illness.
Danger Signs
Seek urgent medical attention immediately if any of the following symptoms develop.
Severe Abdominal Pain
May indicate a serious intestinal complication and requires urgent evaluation.
Confusion
A sign that the infection may be affecting the body more seriously and requires prompt medical care.
Signs of Intestinal Bleeding
Blood in stool or vomit is a medical emergency requiring immediate attention.
High, Unrelenting Fever
Fever that does not improve despite treatment should be reassessed promptly.
Diagnosis
Clinical Assessment
Diagnosis begins with evaluating the pattern and duration of fever, travel history, and physical examination.
Blood Culture
Blood culture remains the reference standard for confirming Salmonella Paratyphi infection, though sensitivity can be limited.
Stool Culture
Stool culture can also identify the organism, particularly later in the course of illness.
Laboratory Tests
Blood Culture
The reference standard for confirming Salmonella Paratyphi infection, though sensitivity may be lower than desired.
Stool Culture
Can identify Salmonella Paratyphi, particularly useful later in the illness or in carriers.
Complete Blood Count (CBC)
Supports diagnosis by identifying patterns consistent with a bacterial infection.
Treatment
Antibiotics
Antibiotics such as ceftriaxone or azithromycin are commonly used as first-line treatment, guided by local resistance patterns.
Supportive Care
Fluid replacement and fever management support recovery alongside antibiotic treatment.
Prevention
Wash hands regularly
Frequent handwashing, especially before eating and after using the toilet, reduces the risk of fecal-oral transmission.
Drink safe water
Drinking treated, boiled, or bottled water reduces exposure to contaminated water sources.
Practise safe food handling
Thoroughly cooking food and being cautious with raw fruits, vegetables, and shellfish reduces risk.
Seek early testing and treatment
Anyone with prolonged fever in an area where enteric fever is common should seek prompt testing.
Risk Factors
High Risk
These individuals are more likely to develop complications.
- Young children
- People with limited access to healthcare
- People with chronic carriage of the bacteria
Increased Risk
These groups have a higher chance of acquiring paratyphoid fever.
- Travellers to endemic regions
- People living in areas with poor sanitation
- Food handlers and their contacts
Exposure Factors
Environmental and behavioural factors that increase the risk of transmission.
- Contaminated water sources
- Consuming raw fruits, vegetables, or shellfish from unclear sources
- Close contact with an infected person
Complications
Intestinal Bleeding
Untreated or severe infection can lead to intestinal bleeding, particularly in the second or third week of illness.
Intestinal Perforation
A serious complication requiring emergency surgical care.
Bloodstream Infection
The bacteria can spread into the bloodstream, causing more widespread illness.
When to Seek Medical Care
Severe Abdominal Pain
May indicate a serious intestinal complication and requires urgent evaluation.
Blood in Stool or Vomit
A sign of possible intestinal bleeding and a medical emergency.
Confusion
Requires prompt medical assessment.
Fever Not Improving with Treatment
Should be reassessed by a healthcare provider promptly.
Prognosis
Good with Prompt Treatment
Most people recover fully when paratyphoid fever is diagnosed and treated appropriately with antibiotics.
Milder Than Typhoid, but Not Harmless
Paratyphoid fever is generally milder than typhoid fever, but delayed treatment can still lead to serious complications.
Possible Chronic Carriage
A small number of people continue to carry the bacteria after recovery and may need further treatment.
Differential Diagnosis
Typhoid Fever
The most important differential diagnosis, since typhoid and paratyphoid fever share nearly identical presentations, transmission, and management, but are caused by different Salmonella serotypes.
Malaria
Malaria can present with fever and malaise similar to paratyphoid fever, particularly in overlapping endemic areas.
Cholera
Cholera shares the same fecal-oral transmission route, but typically presents with sudden severe watery diarrhea rather than prolonged fever.
References
CDC Yellow Book 2026
CDC clinical guidance for healthcare professionals on diagnosing, treating, and preventing typhoid and paratyphoid fever in travellers.
Britannica
Overview of paratyphoid fever, its causes, transmission, and clinical presentation.
AMBOSS
Clinical reference on the diagnosis, staging, and treatment of typhoid and paratyphoid fever.
Frequently Asked Questions
Is paratyphoid fever the same as typhoid fever?
No, though they are closely related. Both are forms of enteric fever caused by related Salmonella bacteria, but paratyphoid fever is generally milder than typhoid fever.
Can paratyphoid fever be cured?
Yes. Most people recover fully with appropriate antibiotic treatment.
How does paratyphoid fever spread?
It spreads through food or water contaminated with feces from an infected person, including people who show no symptoms themselves.
Does the typhoid vaccine protect against paratyphoid fever?
No. Typhoid vaccines do not protect against paratyphoid fever, so safe food and water practices remain important even for vaccinated travellers.