Paratyphoid Fever

How paratyphoid fever spreads

Paratyphoid bacteria live only in humans. People become infected by eating food or drinking water contaminated with stool from a person who is ill or who carries the bacteria without symptoms. Common sources are:

• untreated drinking water and ice
• raw fruits and vegetables washed in contaminated water
• food prepared by an infected person who did not wash their hands
• shellfish from contaminated water

The incubation period is usually 1 to 10 days, sometimes longer. In the US, most cases are acquired abroad, with travel to India, Pakistan and Bangladesh posing the highest risk.

Symptoms

Symptoms are similar to, though often slightly milder than, typhoid fever:

• fever that climbs gradually over several days, often to 39 to 40 °C (102 to 104 °F)
• headache
• weakness, fatigue and loss of appetite
• abdominal pain
• constipation or diarrhea
• dry cough
• a relatively slow pulse for the fever level
• rose spots: faint pink spots on the chest or abdomen, in some people
• an enlarged spleen or liver

Without treatment, fever can last weeks.

Paratyphoid vs typhoid fever

Because symptoms overlap with malaria, dengue and other travel infections, testing is essential.

Diagnosis

• Blood cultures: the main test, most reliable in the first week.
• Stool and urine cultures: positive later in the illness.
• Bone marrow culture: the most sensitive, used when other cultures are negative.
• Antibiotic sensitivity testing: essential given widespread resistance.
• Other tests: blood count, liver tests, and malaria and dengue tests in returning travelers.

Older antibody tests such as the Widal test are unreliable.

Treatment

• Antibiotics: Paratyphi A from South Asia is often resistant to fluoroquinolones such as ciprofloxacin. Common treatments are azithromycin for uncomplicated illness, and ceftriaxone or other IV antibiotics for severe illness, adjusted to culture results. Fever may take 3 to 5 days to settle after starting antibiotics.
• Fluids and rest: drink plenty or receive IV fluids if dehydrated.
• Fever relief: acetaminophen (paracetamol). Follow the label dose.
• Hospital care for severe illness or complications.

Complete the full antibiotic course. Food handlers, healthcare workers and childcare workers may need negative stool tests before returning to work.

Complications

Uncommon with prompt treatment, but can include:

• intestinal bleeding or perforation, typically in the third week
• dehydration
• inflammation of the gallbladder, liver, heart or brain
• relapse after treatment
• chronic carrier state, with bacteria persisting in the gallbladder

Prevention

There is no licensed vaccine for paratyphoid fever. Typhoid vaccines are still recommended for travel to high-risk areas, as they protect against typhoid, but food and water precautions are the main protection against paratyphoid:

• drink bottled, boiled or treated water; avoid ice unless made from safe water
• eat food that is thoroughly cooked and served hot
• avoid raw vegetables and fruit you cannot peel yourself
• avoid street food that is not freshly cooked
• wash hands with soap, especially before eating and after using the toilet; carry alcohol-based hand sanitizer as a backup

Frequently asked questions

What are the symptoms of paratyphoid fever?

Symptoms include a fever that gradually rises over several days, headache, weakness, loss of appetite, abdominal pain, and either constipation or diarrhea. Some people develop faint pink spots on the chest or abdomen.

How is paratyphoid fever spread?

It spreads through food or water contaminated with the stool of an infected person. Common sources include untreated water, ice, raw produce and food handled by someone with the infection. Only humans carry the bacteria.

Does the typhoid vaccine protect against paratyphoid?

Not reliably. Typhoid vaccines protect against Salmonella Typhi, and offer little or no protection against paratyphoid. Careful food and water hygiene is the main way to prevent paratyphoid fever when traveling.

How is paratyphoid fever treated?

It is treated with antibiotics, commonly azithromycin or ceftriaxone, chosen according to where the infection was acquired and test results, because resistance to older antibiotics is common. Most people recover fully with treatment.