Paratyphoid Fever
A typhoid-like infection spread through contaminated food and water
Quick Facts
- Type: Bacterial infection (enteric fever)
- Cause: Salmonella Paratyphi
- Spread: Contaminated food and water
- Treatment: Antibiotics, fluids
Overview
Paratyphoid fever is a bacterial infection caused by Salmonella enterica serotype Paratyphi (types A, B, and C). It is closely related to typhoid fever, and together the two are known as enteric fever. The bacteria are spread when food or water contaminated with the feces of an infected person is swallowed.
After being swallowed, the bacteria pass through the gut wall and spread through the bloodstream, causing a prolonged fever and a range of digestive and general symptoms. Paratyphoid fever tends to be somewhat milder than typhoid, but it can still cause serious illness, particularly in places with limited access to clean water and sanitation. It responds well to prompt antibiotic treatment.
Symptoms
Symptoms usually appear gradually one to three weeks after infection and may build over several days. They include:
- A sustained fever that often rises day by day
- Headache and general body aches
- Weakness, tiredness, and loss of appetite
- Abdominal pain and discomfort
- Constipation or diarrhea
- Nausea
- Sometimes a faint rash of small rose-colored spots on the trunk
Without treatment, the illness can drag on for weeks and, in severe cases, lead to dangerous complications such as intestinal bleeding or a hole in the bowel wall. Severe abdominal pain, persistent vomiting, or signs of severe dehydration require urgent care.
Causes
Paratyphoid fever is caused by Salmonella Paratyphi bacteria, which live only in humans. The infection spreads through what is called the fecal-oral route:
- Contaminated water: Drinking water that has been mixed with sewage.
- Contaminated food: Food handled by an infected person who did not wash their hands, or food washed in unsafe water.
- Carriers: Some people who recover continue to carry and shed the bacteria for a long time and can pass the infection to others.
The disease is most common in regions with poor sanitation and limited access to safe drinking water, and it is often acquired during travel to these areas.
Risk Factors
- Travel to or living in areas with poor sanitation
- Drinking untreated water or eating food from unsafe sources
- Close contact with an infected person or a carrier
- Working in sanitation or with sewage
- Limited access to handwashing and clean water
Diagnosis
Because the symptoms overlap with many other infections, laboratory tests are needed to confirm paratyphoid fever:
- Blood culture: Growing the bacteria from a blood sample is the main way to confirm the diagnosis.
- Stool or urine culture: Can also detect the bacteria, especially later in the illness.
- Bone marrow culture: Occasionally used when blood cultures are negative but suspicion remains high.
A travel history and gradual onset of sustained fever help point doctors toward enteric fever.
Treatment
Paratyphoid fever is treated with antibiotics, and supportive care helps the body recover.
- Antibiotics: A course of antibiotics clears the infection. The specific choice depends on local resistance patterns, which is why a doctor's guidance is important.
- Fluids: Drinking enough fluids, or receiving them intravenously in hospital, prevents and treats dehydration.
- Rest and nutrition: Adequate rest and easily digested food support recovery.
- Monitoring: Severe cases are watched in hospital for complications such as intestinal bleeding.
Most people improve within a few days of starting effective antibiotics, but it is important to complete the full course to clear the infection and reduce the chance of becoming a carrier.
Prevention
- Drink only safe water that is bottled, boiled, or properly treated when in high-risk areas
- Eat food that is freshly cooked and served hot, and peel fruit yourself
- Avoid ice, raw vegetables, and food from street vendors in high-risk areas
- Wash hands thoroughly with soap, especially before eating and after using the toilet
- If you have had the infection, follow advice on follow-up testing to confirm you are no longer a carrier before handling food for others
When to See a Doctor
See a doctor if you develop a sustained fever, especially after traveling to an area where enteric fever is common. Seek urgent care if you have severe abdominal pain, vomiting blood or passing black or bloody stools, persistent vomiting, confusion, or signs of severe dehydration such as very little urine, dizziness, or extreme weakness, as these can indicate serious complications.
Frequently Asked Questions
What is the difference between typhoid and paratyphoid fever?
Both are forms of enteric fever spread by contaminated food and water, but they are caused by different bacteria, Salmonella Typhi and Salmonella Paratyphi. Paratyphoid is often slightly milder, though the symptoms and treatment are very similar.
How do you catch paratyphoid fever?
It spreads through food or water contaminated with feces from an infected person or carrier. It is most common where sanitation is poor and is often acquired during travel to high-risk areas.
How is paratyphoid fever treated?
Treatment is a course of antibiotics chosen based on local resistance patterns, along with plenty of fluids and rest. Most people improve within days of starting effective antibiotics, but the full course should be completed.
Is there a vaccine for paratyphoid fever?
Routine typhoid vaccines do not reliably protect against paratyphoid fever. The best protection is careful food and water hygiene when traveling to areas where enteric fever is common.
Can paratyphoid fever be dangerous?
Most people recover with prompt antibiotics, but untreated infection can cause serious complications such as intestinal bleeding or perforation. Severe abdominal pain, bloody stools, or signs of severe dehydration need urgent medical care.
References
- Centers for Disease Control and Prevention (CDC). Typhoid and Paratyphoid Fever.
- World Health Organization (WHO). Enteric fever.
- MedlinePlus, U.S. National Library of Medicine. Paratyphoid fever.
- Mayo Clinic. Typhoid fever.