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Information for Healthcare Professionals

Resources for Clinicians

cover of cdc yellow book 2018

Get more information on these diseases in CDC’s Yellow Book, a reference for health professionals providing care to international travelers.

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CDC’s Traveler’s Health site has information you can use to help your patients have a healthy trip, including:

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Clinical Features

Typhoid fever and paratyphoid fever are bacteremic illnesses that have an insidious onset characterized by fever, headache, constipation or diarrhea, malaise, chills, and myalgias, with few clinical features that reliably distinguish them from a variety of other infectious diseases. Diarrhea may occur, and vomiting is not usually severe. A transient, maculopapular rash of rose-colored spots may be present on the trunk. Confusion, delirium, and intestinal perforation may occur in severe cases, typically after 2–3 weeks of illness. The incubation period for typhoid fever is typically 6–30 days and for paratyphoid fever, 1–10 days.

Diagnosis

Blood culture is the mainstay of diagnosis. Bone marrow cultures have sensitivity of 80% in some studies and can remain positive despite antibiotic therapy. Stool and urine cultures are positive less frequently. Multiple cultures are usually needed to identify the pathogen. Serologic tests, such as the Widal test, are not recommended because of the high rate of false positives.

Etiologic Agent 

Salmonella enterica serotype Typhi for typhoid fever and Salmonella enterica serotype Paratyphi for paratyphoid fever.

Incidence 

In the United States, about 350 patients are diagnosed with typhoid fever and 90 patients are diagnosed with paratyphoid fever annually, mostly among people who report recent travel to countries, such as India, Bangladesh, and Pakistan. An estimated 22 million cases of typhoid fever and 200,000 deaths occur worldwide each year. An estimated 5 million cases of paratyphoid fever occur worldwide each year.

Sequelae

Without therapy, the illness can last for 3–4 weeks and death rates range between 12% and 30%. Relapse occurs in up to 10% of untreated patients approximately 1–3 weeks after recovering from the initial illness and is often more mild than the initial illness. A chronic carrier state, in which stool or urine cultures for Salmonella Typhi remain positive for more than 1 year, occurs in up to approximately 5% of infected persons.

Transmission

Typhoid fever and paratyphoid fever are transmitted commonly through the consumption of drinking water or food contaminated with the feces of people who have typhoid fever cases or are chronic carriers.

Risk Groups

Risk is very low in the United States, higher among international travelers, and highest among people living in poverty in the developing world. Most typhoid and paratyphoid fever patients in the United States report international travel in the 30 days before their illness; most of these patients traveled to Southern Asia (e.g., India, Pakistan).

Surveillance

CDC has conducted surveillance for typhoid fever since 1975 and paratyphoid fever since 2008. Approximately 350 culture-confirmed cases of typhoid fever and 90 culture-confirmed cases of paratyphoid fever were reportedly annually to CDC’s National Typhoid and Paratyphoid Fever Surveillance (NTPFS) system during 2008–2015. These cases do not account for people who do not seek medical care, who are not tested for either disease, or whose disease is not reported to CDC.

The actual number of patients with typhoid and paratyphoid fever may be greater because some people who are ill do not seek medical care, some might not be tested, and some who test positive might not be reported to CDC. CDC tracks changes in antibiotic resistance among Salmonella causing typhoid fever and paratyphoid fever through the National Antimicrobial Resistance Monitoring System (NARMS).

Trends

There has been a modest decrease in typhoid fever cases in the United States since 2008.

Challenges

Reduced susceptibility to fluoroquinolones (e.g., ciprofloxacin) and the emergence of multidrug resistance has complicated treatment of infections, especially those acquired in South Asia. There have also been sporadic reports and at least one documented outbreak of ceftriaxone-resistant Salmonella Typhi infections.

Opportunities

The role of new vaccines to control epidemics or to eliminate the disease has not been explored yet. These new vaccines include two typhoid fever protein conjugated vaccines licensed for use in India.

Guidelines for Submitting a Specimen to CDC

CDC offers testing for Salmonella Typhi and Salmonella Paratyphi.

NOTE: CDC accepts specimens for analysis only from state public health laboratories and other federal agencies. Private healthcare providers and institutions must submit specimens to their state public health laboratory for processing.

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