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.
Key Fact
Warning
AT A GLANCE
Disease Summary
Symptoms
Common Symptoms
Most people with paratyphoid fever experience one or more of the following symptoms, generally milder than in typhoid fever.
Sustained Fever
Headache
Weakness and Fatigue
Rose-Coloured Spots
Danger Signs
Seek urgent medical attention immediately if any of the following symptoms develop.
Severe Abdominal Pain
Confusion
Signs of Intestinal Bleeding
High, Unrelenting Fever
Diagnosis
Clinical Assessment
Blood Culture
Stool Culture
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.
Laboratory Note
Blood or bone marrow culture remain the reference standard for diagnosis, despite the limited sensitivity of blood culture alone.
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.
Treatment Note
Most people begin to improve within days of starting appropriate antibiotics. Completing the full course is important even after symptoms improve.
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.
Prevention Note
Vaccination is not fully protective against paratyphoid fever, so safe food and water precautions remain important even after vaccination against typhoid.
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
Risk Note
Overcoming paratyphoid fever does not provide lifelong immunity, and reinfection is possible.
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.
Complication Note
Complications are more likely when treatment is delayed. Prompt antibiotic treatment greatly reduces the risk of serious outcomes.
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.
Emergency Advice
Prolonged fever should always be evaluated by a healthcare provider, particularly in areas where enteric fever is common.
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.
Prognosis Note
Prompt diagnosis and appropriate antibiotic treatment are the most important factors in a full recovery.
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.
Clinical Note
Because paratyphoid fever closely resembles typhoid fever and other febrile illnesses, laboratory testing is important to guide accurate diagnosis and treatment.
References
CDC Yellow Book 2026
CDC clinical guidance for healthcare professionals on diagnosing, treating, and preventing typhoid and paratyphoid fever in travellers.
AMBOSS
Clinical reference on the diagnosis, staging, and treatment of typhoid and paratyphoid fever.