Paratyphoid Fever Is Rising in Returning Travelers, and Your Typhoid Vaccine Won't Stop It

Last updated: August 26, 2026

Paratyphoid fever, caused by Salmonella Paratyphi bacteria, sickens an estimated 3.8 million people worldwide each year and causes roughly 23,300 deaths, according to Global Burden of Disease data cited in the CDC Yellow Book. On August 26, 2026, the CDC updated its travel health notice after paratyphoid cases appeared in travelers returning from Yemen, and stated plainly that available vaccines do not protect against it. That is the detail most travelers miss: the typhoid vaccine, oral Vivotif or injectable Typhim Vi, targets a different bacterium, Salmonella Typhi, and does nothing against the Paratyphi strains behind this illness. As Wandr's clinical team sees again and again in pre-trip visits, the only dependable prevention is strict food and water safety, not a vaccine record.

Quick Facts: Paratyphoid Fever and Travel

• Cause: Salmonella enterica serotypes Paratyphi A, B, or C, with Paratyphi A responsible for the large majority of cases worldwide.
• Global burden: An estimated 3.8 million cases and 23,300 deaths per year, with an age-standardized incidence of 51.3 per 100,000 people.
• Vaccine protection: None. Both US typhoid vaccines target Salmonella Typhi only.
• This week's news hook: CDC updated its Yemen travel notice on August 26, 2026 after paratyphoid cases in returning travelers.
• Highest-risk regions: South Asia, parts of the Middle East (including Yemen), sub-Saharan Africa, and Southeast Asia.
• Prevention: Strict food and water safety. There is no shot to fall back on.
• Treatment: Prescription antibiotics, typically azithromycin, after a confirmed diagnosis via blood culture.

What Is Paratyphoid Fever, and How Is It Different From Typhoid?

Paratyphoid fever is a systemic bacterial infection, not a simple stomach bug. It belongs to a family of illnesses called enteric fevers, caused by Salmonella enterica bacteria that invade the bloodstream rather than staying confined to the gut the way most travelers' diarrhea pathogens do. Typhoid fever comes from Salmonella Typhi. Paratyphoid fever comes from three related serotypes, Paratyphi A, B, and C, with Paratyphi A driving the overwhelming majority of paratyphoid cases globally.

Clinically, the two illnesses look almost identical. Both cause a fever that builds gradually over several days, headache, fatigue, and abdominal discomfort. Paratyphoid is often somewhat milder than typhoid, but "often milder" is not the same as harmless: without treatment, either illness can progress to intestinal bleeding, perforation, or a dangerously prolonged fever. A doctor cannot reliably tell the two apart without a blood culture, which is exactly why the distinction between the two vaccines matters so much.

Why Your Typhoid Vaccine Won't Protect You

This is the single most important thing to understand about the CDC's August 2026 update. Both vaccines available in the US, the oral Ty21a vaccine (brand name Vivotif) and the injectable Vi polysaccharide vaccine (brand name Typhim Vi), are built to trigger immunity specifically against Salmonella Typhi. Neither one contains antigens from Salmonella Paratyphi, so neither one generates protective antibodies against it. The CDC's own guidance is unambiguous: available vaccines do not protect against paratyphoid fever.

Even the typhoid protection these vaccines offer is partial and time-limited. The oral Vivotif series has shown roughly 48 to 50 percent efficacy over 2.5 to 3 years in systematic reviews, while the injectable Typhim Vi starts around 69 percent efficacy at one year and declines to about 55 percent by year three. Newer typhoid conjugate vaccines used in some international immunization programs have shown stronger results, with one large trial reporting 80.7 percent efficacy, but that conjugate formulation is not the product being administered to US travelers today, and none of these typhoid-targeted vaccines, old or new, close the paratyphoid gap.

In other words: a traveler who got vaccinated against typhoid before a trip to South Asia or the Middle East can still walk off the plane with a Salmonella Paratyphi infection, and their vaccine record will not have done anything to stop it.

Where the Risk Is Highest for US Travelers

Paratyphoid fever tracks the same fault lines as typhoid fever and traveler's diarrhea generally: places where food handling and water treatment infrastructure are inconsistent. The documented burden is heaviest in South Asia, particularly India, Pakistan, Nepal, and Bangladesh, where Paratyphi A has become an increasingly large share of all enteric fever cases over the past two decades. It also circulates in sub-Saharan Africa and Southeast Asia.

The CDC's current news hook, cases in travelers returning from Yemen, fits this pattern closely. Yemen's prolonged conflict has repeatedly damaged water and sanitation infrastructure, a dynamic that has already driven one of the largest cholera epidemics in modern history in the same country. Contaminated municipal water and disrupted food safety oversight create exactly the conditions Salmonella Paratyphi needs to spread. Travelers heading to any region with unreliable water treatment, whether that is Yemen specifically or another paratyphoid-endemic destination, should treat food and water precautions as the primary defense, not a backup plan.

Symptoms: What Paratyphoid Fever Actually Looks Like

Paratyphoid fever typically starts 1 to 10 days after exposure, though the incubation period can stretch longer. The hallmark is a fever that climbs gradually day over day rather than spiking suddenly the way a flu or malaria attack often does. Alongside the fever, most people develop:

• Headache and general fatigue
• Loss of appetite
• Abdominal pain or tenderness
• Either diarrhea or constipation, sometimes alternating
• In some cases, a faint rash of flat, rose-colored spots on the trunk

Because these symptoms overlap heavily with dengue, malaria, and ordinary travelers' diarrhea, self-diagnosis is unreliable. Any fever that appears during or shortly after travel to a paratyphoid-risk region needs medical evaluation and, ideally, a blood culture rather than guesswork.

How to Actually Prevent It

There is no vaccine to fall back on, so prevention comes down entirely to food and water discipline. The same habits that protect against paratyphoid also cut your risk of cholera, hepatitis A, and standard travelers' diarrhea, which makes them worth taking seriously on every trip to a higher-risk destination:

• Drink only bottled, sealed, or boiled water. Skip tap water entirely, including for brushing your teeth in higher-risk destinations.
• Avoid ice unless you know it was made from purified water.
• Choose food that is served hot and fully cooked. Steam rising off a dish is a good sign.
• Peel fruit yourself rather than eating pre-cut fruit from a buffet or street vendor.
• Be cautious with raw vegetables and salads, which are often rinsed in tap water.
• Wash your hands or use hand sanitizer before eating, every time, not just when it is convenient.

For our full breakdown of food and water safety abroad, see our complete guide to traveler's diarrhea prevention and treatment.

Traveling somewhere paratyphoid fever is a documented risk? Start your free Wandr health check so a clinician can flag the destination-specific risks for your itinerary, including which vaccines actually apply and which do not.

Treatment: Antibiotics, Resistance, and Why This Isn't a Self-Treat Situation

Paratyphoid fever requires prescription antibiotics, and it requires a confirmed diagnosis first. This is a meaningful difference from ordinary travelers' diarrhea, which many travelers manage with a self-treatment antibiotic kit packed before the trip. Paratyphoid is a bloodstream infection, not a gut-limited illness, and undertreating it raises the risk of intestinal perforation, relapse, or a prolonged carrier state.

Antibiotic choice has shifted in recent years because of resistance. Before 2018, more than 99 percent of Salmonella Typhi and Paratyphi isolates tested through CDC's National Antimicrobial Resistance Monitoring System were susceptible to both azithromycin and ceftriaxone. Since then, resistance to fluoroquinolones like ciprofloxacin has become widespread in Salmonella Paratyphi A circulating across South Asia, and azithromycin resistance has also been identified in strains from Bangladesh, Cambodia, India, Nepal, Pakistan, Saudi Arabia, and the United States. In practice, this means azithromycin has become the more commonly preferred first-line option for suspected paratyphoid in many travel-medicine settings, though the right choice depends on where the infection was likely acquired and local resistance data.

Wandr prescribes both azithromycin and ciprofloxacin as part of destination-matched antibiotic kits for travelers' diarrhea, and our Cipro vs. azithromycin comparison breaks down when each one makes sense. For a suspected case of paratyphoid or typhoid fever specifically, though, do not simply reach for a leftover TD kit. Get evaluated first.

What to Do If You Develop a Fever During or After Your Trip

If a fever shows up while you're still traveling or within a few weeks of getting home, don't wait it out. Start a Wandr visit right away so a clinician can review your itinerary, timeline, and symptoms, and coordinate urgent testing if enteric fever is a real possibility. Our complete guide on fever after international travel walks through what a post-trip fever is most likely to be and what to do in the first 24 hours, before you even know whether it's paratyphoid, malaria, dengue, or something else entirely.

Get your prescription through Wandr if you're heading somewhere paratyphoid fever is a known risk, so your antibiotic options are already lined up before you need them.

Medical Disclaimer

This article is for educational purposes and does not replace individualized medical care. Paratyphoid fever requires laboratory diagnosis and prescription treatment. If you develop a fever during or after international travel, seek prompt evaluation rather than self-treating.