National Typhoid and Paratyphoid Fever Surveillance Annual Summary, 2020

Surveillance

Jurisdictions¹ reporting at least one case of Salmonella enterica serotype Typhi, Paratyphi A, Paratyphi B [tartrate negative], or Paratyphi C,² to the National Typhoid and Paratyphoid Fever Surveillance system (NTPFS) during 2020 are shown in Figures 1 and 2. The surveillance system case definitions changed in 2019:

157 Salmonella Typhi cases were reported by 26 jurisdictions (Figure 1).
48 Salmonella Paratyphi cases³ were reported by 19 jurisdictions (Figure 2).

Salmonella Typhi and Paratyphi are bacteria that cause severe and occasionally life-threatening bacteremic illness known as typhoid fever and paratyphoid fever, respectively. This report summarizes all cases of bacterial infection, including those that may be asymptomatic or have atypical clinical presentation.

¹ Includes all 50 states and District of Columbia.
² Two pathotypes of Paratyphi B are recognized, differentiated by the ability to ferment tartrate. The pathotype designated serotype Paratyphi B is unable to ferment tartrate; it causes paratyphoid fever. The other pathotype is designated Paratyphi B var. L(+) tartrate+; it can ferment tartrate and causes uncomplicated gastroenteritis. Only isolates laboratory-confirmed as not able to ferment tartrate are included in this annual summary. Many reports of Paratyphi B detection do not include this information.
³ Zero cases of Salmonella serotype Paratyphi C and eleven cases of Salmonella Paratyphi without a specified serotype reported.

On This Page

Surveillance
Demographic and Clinical Characteristics
International Travel
Typhoid Fever Vaccine
National Notifiable Diseases Surveillance System
Antimicrobial Resistance
Outbreaks

Read an overview of the National Typhoid and Paratyphoid Fever Surveillance (NTPFS) system [PDF – 2 pages]

Figure 1 Figure 2

Salmonella Typhi cases reported to NTPFS by jurisdiction, 2020 (n = 157)

Download Data [XLS – 464 B]

Salmonella Paratyphi cases reported to NTPFS by jurisdiction, 2020 (n = 48)

Download Data [XLS – 464 B]

Demographic and Clinical Characteristics of Patients

Demographic and clinical characteristics of patients with Salmonella Typhi and Paratyphi infections are shown in Tables 1 and 2.

The median age of patients with Salmonella Typhi infections was 26 years (range 0 – 85)
The median age of patients with Salmonella Paratyphi infections was 24 years (range 2 – 73)
There were no deaths among patients with Salmonella Typhi or Paratyphi infections.

Table 1

Demographic and clinical characteristics of patients with typhoid fever reported to NTPFS, 2018 (n =370)
Characteristic (number with data available)	Number	Percent
Age group, years (n = 154) <1	1	<1
1–4	23	15
5–14	28	18
15–24	19	12
25–44	47	31
45–64	28	18
65+	8	5
Female (n = 156)	74	47
Food handler (n = 98)	4	4
Outbreak-associated (n = 128)	3	2
International travel¹ (n = 149)	113	76
Vaccinated² (n = 92)	6	7
Specimen source (n = 145)
Blood	124	86
Stool	19	13
Other	2	1
Hospitalizations³ (n = 154)	126	82
Deaths (n = 141)	0	0

¹ Travel destinations are shown in Table 3a.
² Received typhoid fever vaccination within five years before onset of illness; of the six cases in vaccinated persons, four received only the Vi capsular polysaccharide vaccine (ViCPS). Vaccine type was not reported for the other two cases.
³ Median length of hospitalization was six days.

Table 2

Demographic and clinical characteristics of patients with paratyphoid fever reported to NTPFS, 2018 (n = 128)
Characteristic (number with data)	Number	Percent
Age group, years (n = 47) <1	0	0
1–4	3	6
5–14	4	9
15–24	12	25
25–44	20	43
45–64	2	4
65+	6	13
Female (n = 48)	27	56
Food handler (n = 27)	1	4
Outbreak-associated (n = 37)	0	0
International travel¹ (n = 46)	35	76
Specimen source (n = 44)
Blood	35	80
Stool	6	14
Other	3	7
Hospitalizations² (n = 48)	37	71
Deaths (n = 43)	0	0

¹ Travel destinations are shown in Table 3b
² Median length of hospitalization was four days.

International Travel

Among the 149 patients with Salmonella Typhi infections whose travel histories were reported, 113 (76%) reported traveling or living outside the United States in the 30 days before illness.
Among the 46 patients with Salmonella Paratyphi infections whose travel histories were reported, 35 (76%) reported traveling or living outside the United States in the 30 days before illness.
Among patients reporting international travel, 99 (66%) patients with Salmonella Typhi infections and 33 (94%) patients with Salmonella Paratyphi infections reported travel to a single destination (Tables 3a and 3b). More than 75% of patient with either pathogen reported travel to India or Pakistan.
54 (48%) patients with Salmonella Typhi infection and 16 (64%) patients with Salmonella Paratyphi infection reported visiting friends or relatives, which was the most commonly reported reason for international travel.

Table 3a

Travel destinations for patients with typhoid fever who reported a single destination country, NTPFS, 2018
Travel Destination	No. (%)
India	51 (52)
Pakistan	27 (27)
Mexico	7 (7)
Bangladesh	5 (5)
El Salvador	4 (4)
Other¹	5 (5)

¹ Phillipines (2), Ghana (1), Nigeria (1), Thailand (1)

Table 3b

Travel destinations for patients with paratyphoid fever who reported a single destination country, NTPFS, 2018
Travel Destination	No. (%)
India	19 (58)
Pakistan	9 (27)
Cambodia	2 (6)
Burma	2 (6)
Bangladesh	1 (3)

Typhoid Fever Vaccine

Download Data [XLS – 67 B]

¹ Figure excludes patients whose typhoid vaccination status was unknown or not reported (n = 65).

National Notifiable Diseases Surveillance System

The National Notifiable Diseases Surveillance System (NNDSS) collects and compiles reports of nationally notifiable infectious diseases, including Salmonella Typhi and Paratyphi cases. NNDSS reports can be found at www.cdc.gov/nndss/data-statistics.

The figure below presents a comparison of Salmonella Typhi case reports submitted to NTPFS and NNDSS in the past five years. Reports submitted to NNDSS, but not NTPFS, can include clinically compatible cases that are epidemiologically linked to a confirmed case but are not laboratory-confirmed.

Comparisons for Salmonella Paratyphi are not provided because, although it was nationally notifiable, NNDSS does not report subtyping information for this condition.

Download Data [XLS – 91 B]

¹ NNDSS data from some reporting areas may be incomplete due to the coronavirus disease 2019 (COVID-19) pandemic or due to post-reconciliation data updates that could not be confirmed or included in the final data set (NNDSS, 2020)

Antimicrobial Resistance

The National Antimicrobial Resistance Monitoring System (NARMS) monitors antimicrobial resistance among enteric bacteria (including Salmonella enterica serotypes Typhi and Paratyphi A, Paratyphi B, and Paratyphi C) from humans. Among Typhi, decreased susceptibility to ciprofloxacin (DSC) (minimum inhibitory concentration ≥0.12 µg/mL) has been associated with fluoroquinolone treatment failure. Multidrug-resistance (MDR) is defined as resistance to ampicillin, chloramphenicol, and trimethoprim-sulfamethoxazole.

Among Salmonella Typhi isolates during 2020:

86% had DSC
25% were MDR
26.2% were resistant to three or more classes of antibiotics
19.4% were resistant to ceftriaxone

Among Salmonella Paratyphi A isolates during 2020:

99% had DSC
No isolates were MDR
No isolates were resistant to three or more classes of antibiotics
No isolates were resistant to ceftriaxone

Data on resistance are available in NARMS Now, an interactive tool containing antibiotic resistance data from bacteria isolated from humans.

Outbreaks

The Foodborne Disease Outbreak Surveillance System (FDOSS) collects reports of foodborne disease outbreaks from local, state, tribal, and territorial public health agencies. The most recently published annual reports are available at www.cdc.gov/fdoss/annual-reports.

The Waterborne Disease and Outbreak Surveillance System (WBDOSS) collects reports of waterborne disease outbreaks associated with drinking and recreational water from local, state, tribal, and territorial public health agencies. Reports are available at www.cdc.gov/healthywater/surveillance/surveillance-reports.html.

In 2020, there were no outbreaks of typhoid fever or paratyphoid fever.

References

CDC. National Antimicrobial Resistance Monitoring System (NARMS) Now: Human Data. Atlanta, Georgia: U.S. Department of Health and Human Services, CDC. https://wwwn.cdc.gov/narmsnow. Accessed 5/1/2023.

Recommended Citation

Centers for Disease Control and Prevention (CDC). National Typhoid and Paratyphoid Fever Surveillance Annual Report, 2020. Atlanta, Georgia: US Department of Health and Human Services, CDC, 2023

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