Incidence, death, and DALY of eight bacterial diseases and temporal trendSyphilis

In 2021, the global ASIR for syphilis was 235.47 per 100,000 population (95% UI: 176.40, 307.43 per 100,000 population), with an increase of 8.55% (95% UI: 6.32, 10.79%) compared to 1990. The global age-standardized DALY rate for syphilis was estimated at 107.13 per 100,000 population (95% UI: 41.77, 212.12 per 100,000 population), with a percentage change of −15.10% (95% UI: − 29.51, 0.04%) compared to 1990, which did not show a significant upward or downward trend (P > 0.05, equally, Table 1). Syphilis showed an ASMR of 1.19 per 100,000 population (95% UI: 0.47, 2.36 per 100,000 population), declining by − 16.22% (95% UI: − 30.91, − 1.37%) compared to 1990 (Additional file 1: Table S1).

Table 1 Age-standardized incidence and DALY rates for syphilis in 1990 and 2021, and the percentage change in the age-standardized rates per 100,000 population by GBD region, from 1990 to 2021

The ASIR for syphilis was 312.53 per 100,000 population (95% UI: 234.16, 406.22 per 100,000 population) in males in 2021, with an increase of 9.48% (95% UI: 7.73, 11.42%) compared to 1990. The ASIR for syphilis was 157.00 per 100,000 population (95% UI: 115.35, 204.53 per 100,000 population) in females, with an increasing of 7.06% (95% UI: 3.60, 10.24%) compared to 1990. However, age-standardized DALY rate and ASMR of syphilis show no significant differences between male and female individuals in 2021 (P > 0.05, equally, Table 1).

Gonococcal infection

In 2021, the global ASIR for gonococcal infection was 1096.58 per 100,000 population (95% UI: 838.70, 1385.47 per 100,000 population), with a decline of − 4.24% (95% UI: − 7.45, − 1.00%) compared to 1990. The global age-standardized DALY rate for gonococcal infection was 0.91 per 100,000 population (95% UI: 0.64, 1.29 per 100,000 population), declining by − 13.60% (95% UI: − 21.38, − 6.34%) compared to 1990 (Table 2). The ASMR for gonococcal infection was very low in both 1990 and 2021, with less than 0.10 per 100,000 population regardless of GBD region, gender, and five SDI groups (Additional file 1: Table S2).

Table 2 Age-standardized incidence and DALY rates for gonococcal infection in 1990 and 2021, and the percentage change in the age-standardized rates per 100,000 population by GBD region, from 1990 to 2021

In 2021, the ASIR of gonococcal infection in males was 1451.24 per 100,000 population (95% UI: 1114.01, 1839.68 per 100,000 population) which is significantly higher than that in females (732.67 per 100,000 population, 95% UI: 560.93, 937.39 per 100,000 population, P < 0.05). The ASIR of gonococcal infection remained stable in males (percentage change = 0.44, 95% UI: − 2.30, 3.04) and decreased by − 12.62% (95% UI: − 17.38, − 7.08) in females compared to 1990. A similar trend was observed for the age-standardized DALY rates: remained stable in males (percentage change = − 8.24, 95% UI: − 21.60, 0.18) and decreased in females (percentage change = − 23.14, 95% UI: − 31.61, − 13.13, Table 2).

Typhoid fever

For typhoid fever, the global ASIR was estimated at 98.56 per 100,000 population (95% UI: 76.64, 126.77 per 100,000 population) in 2021, decreasing by − 69.57% (95% UI: − 72.01, − 66.64%) compared to 1990. The global age-standardized DALY rate was 101.09 per 100,000 population (95% UI: 51.43, 176.36 per 100,000 population), with a decline of − 59.23% (95% UI: − 67.07, − 50.70%) compared to 1990 (Table 3). The global ASMR for typhoid fever was 1.30 per 100,000 population (95% UI: 0.65, 2.24 per 100,000 population) in 2021, decreasing − 59.49% (95% UI: − 66.63, − 51.59%, Additional file 1: Table S3).

Table 3 Age-standardized incidence and DALY rates for typhoid fever in 1990 and 2021, and the percentage change in the age-standardized rates per 100,000 population by GBD region, from 1990 to 2021

In 2021, the ASIR of typhoid fever in males and females were 107.22 per 100,000 population (95% UI: 83.70, 137.25 per 100,000 population) and 89.54 per 100,000 population (95% UI: 69.14, 116.33 per 100,000 population), respectively. The age-standardized DALY rates in males and females were 101.09 per 100,000 population (95% UI: 51.43, 176.36 per 100,000 population) and 95.73 per 100,000 population (95% UI: 49.06, 168.07 per 100,000 population), respectively (Table 3).

Paratyphoid fever

In 2021, the global ASIR, age-standardized DALY and ASMR for paratyphoid fever were 29.21 per 100,000 population (95% UI: 21.15, 40.28 per 100,000 population), 14.16 per 100,000 population (95% UI: 6.33, 27.37 per 100,000 population), and 0.19 per 100,000 population (95% UI: 0.09, 0.38 per 100,000 population), both declining at least − 72.00% compared to 1990 (Table 4 and Additional file 1: Table S4). The paratyphoid ASMR was very low in 2021, with less than 0.80 per 100,000 population regardless of GBD region, gender, and five SDI groups (Additional file 1: Table S4).

Table 4 Age-standardized incidence and DALY rates for paratyphoid fever in 1990 and 2021, and the percentage change in the age-standardized rates per 100,000 population by GBD region, from 1990 to 2021

In 2021, the paratyphoid ASIR in males and females were 31.44 per 100,000 population (95% UI: 22.63, 43.52 per 100,000 population) and 26.88 per 100,000 population (95% UI: 19.21, 36.78 per 100,000 population), respectively. The age-standardized DALY rates in males and females were 14.45 per 100,000 population (95% UI: 6.49, 27.88 per 100,000 population) and 13.87 per 100,000 population (95% UI: 6.09, 26.64 per 100,000 population), respectively (Table 4).

Diphtheria

In 2021, the global ASIR (0.19 per 100,000 population, 95% UI: 0.13, 0.27 per 100,000 population) and ASMR (0.06 per 100,000 population, 95% UI: 0.04, 0.08 per 100,000 population) for diphtheria were both very low. Regardless of the GBD region, gender, or SDI categories, they are below 1.20 per 100,000 population and 0.40 per 100,000 population, respectively. The global age-standardized DALY rate was estimated at 4.75 per 100,000 population (95% UI: 3.19–6.82 per 100,000 population). Compared to 1990, diphtheritia ASIR, age-standardized DALY rate, and ASMR have all decreased by at least − 85.00% (Table 5 and Additional file 1: Table S5).

Table 5 Age-standardized incidence and DALY rates for diphtheria in 1990 and 2021, and the percentage change in the age-standardized rates per 100,000 population by GBD region, from 1990 to 2021

In 2021, global diphtheritic ASIR in males (0.19 per 100,000 population, 95% UI: 0.13, 0.28 per 100,000 population) and females (0.20 per 100,000 population, 95% UI: 0.12, 0.29 per 100,000 population) were very close. Similarly, the age-standardized DALY rates in males (4.99 per 100,000 population, 95% UI: 3.27, 7.45 per 100,000 population) and females (4.50 per 100,000 population, 95% UI: 2.87, 6.59 per 100,000 population) were also close (Table 5).

Pertussis

In 2021, the global ASIR for pertussis was 110.61 per 100,000 population (95% UI: 78.48, 156.93 per 100,000 population), with a decrease of − 78.90% (95% UI: − 82.85, − 73.62%) compared to 1990. The global age-standardized DALY rate for pertussis was estimated at 70.92 per 100,000 population (95% UI: 31.90, 142.08 per 100,000 population), with a percentage change by − 81.24% (95% UI: − 89.10, − 63.77%) compared to 1990 (Table 6). Pertussis showed an ASMR of 0.81 per 100,000 population (95% UI: 0.36, 1.63 per 100,000 population), declining by − 81.32% (95% UI: − 89.81, − 63.91%) compared to 1990 (Additional file 1: Table S6).

Table 6 Age-standardized incidence and DALY rates for pertussis in 1990 and 2021, and the percentage change in the age-standardized rates per 100,000 population by GBD region, from 1990 to 2021

The ASIR for pertussis was 99.84 per 100,000 population (95% UI: 70.76, 141.72 per 100,000 population) in males in 2021, with a decline of −78.96% (95% UI: − 82.96, − 73.64%) compared to 1990. The ASIR for pertussis was 122.12 per 100,000 population (95% UI: 86.72, 172.80 per 100,000 population) in females, decreasing by − 78.83% (95% UI: − 82.76, − 73.59%) compared to 1990. However, age-standardized DALY rate and ASMR of pertussis show no significant differences between male and female individuals in 2021 (P > 0.05, equally, Table 6).

Tetanus

In 2021, the global ASIR (0.69 per 100,000 population, 95% UI: 0.30, 1.09 per 100,000 population) and ASMR (0.29 per 100,000 population, 95% UI: 0.13, 0.45 per 100,000 population) for tetanus were both very low. Without regard to the GBD region, gender, or SDI categories, they are below 3.40 per 100,000 population and 2.00 per 100,000 population, respectively. The global age-standardized DALY rate was estimated at 19.53 per 100,000 population (95% UI: 8.59, 32.34 per 100,000 population). Compared to 1990, tetanus ASIR, age-standardized DALY rate, and ASMR have all decreased by at least −91.00% (Table 7 and Additional file 1: Table S7).

Table 7 Age-standardized incidence and DALY rates for tetanus in 1990 and 2021, and the percentage change in the age-standardized rates per 100,000 population by GBD region, from 1990 to 2021

In 2021, global tetanus ASIR in males and females were 0.82 per 100,000 population (95% UI: 0.33, 1.40 per 100,000 population) and 0.56 per 100,000 population (95% UI: 0.24, 0.92 per 100,000 population). The age-standardized DALY rates in males and females were 20.71 per 100,000 population (95% UI: 8.00, 36.83 per 100,000 population) and 18.38 per 100,000 population (95% UI: 8.38, 31.62 per 100,000 population, Table 7).

Leprosy

From 1990 to 2021, no estimates of leprosy deaths and ASMR were reported in the database. In 2021, the global ASIR for leprosy was 0.58 per 100,000 population (95% UI: 0.50, 0.68 per 100,000 population), with a decrease of − 64.79% (95% UI: − 65.48, − 64.00%) compared to 1990. The global age-standardized DALY rate for leprosy was 0.25 per 100,000 population (95% UI: 0.17, 0.37 per 100,000 population), declining by − 56.32% (95% UI: − 58.03, − 54.59%) compared to 1990 (Table 8).

Table 8 Age-standardized incidence and DALY rates for leprosy in 1990 and 2021, and the percentage change in the age-standardized rates per 100,000 population by GBD region, from 1990 to 2021

In 2021, global ASIR for leprosy in males was 0.76 per 100,000 population (95% UI: 0.65, 0.89 per 100,000 population) which is significantly higher than in that in females (0.40 per 100,000 population, 95% UI: 0.34, 0.47 per 100,000 population, P < 0.05). The age-standardized DALY rates in males and females were 0.32 per 100,000 population (95% UI: 0.21, 0.47 per 100,000 population) and 0.19 per 100,000 population (95% UI: 0.13, 0.29 per 100,000 population, Table 8).

Global distribution of eight bacterial diseasesSyphilis

For syphilis in 2021, the ASIR was highest in Central sub-Saharan Africa, followed by Eastern sub-Saharan Africa and Southern sub-Saharan Africa, exceeding 460.00 per 100,000 population (Table 1). The countries with the highest ASMR for syphilis are Equatorial Guinea, Central African Republic, and the Democratic Republic of the Congo. In contrast, the regions with an ASIR below 100.00 per 100,000 population include Central Europe, Central Asia, and Western Europe (Table 1), among which the top three lowest ASIR countries were Bulgaria, Slovakia, and Croatia. The age-standardized DALY rate had a similar geographical distribution, being highest in Central, Eastern and Southern sub-Saharan Africa, greater than 100.00 per 100,000 population (Table 1), and South Sudan, the Central Africa Republic, and Liberia had the dominant DALY rates. In contrast, the age-standardized DALY rate was lowest in high-income North America and Australasia, both below 1.00 per 100,000 population (Additional file 1: Table S9).

Gonococcal infection

Gonococcal infection had the highest ASIR in Southern sub-Saharan Africa, followed by Oceania and Central Europe in 2021, exceeding 2170.00 per 100,000 population (Table 2). South Africa, Papua New Guinea and Lesotho were three countries with the highest ASIR. Age-standardized DALY rate was highest in Eastern sub-Saharan Africa, and Central sub-Saharan Africa (Table 2). Somalia, Lesotho, and South Africa were the three age-standardized highest DALY rate countries for gonococcal infection (Additional file 1: Table S9).

Typhoid fever

The ASIR of typhoid fever was highest in Oceania, South Asia, and Southeast Asia in 2021, exceeding 142.00 per 100,000 population (Table 3). The age-standardized DALY rate and ASMR had the same trends, which are also dominant in these three regions (Table 3 and Additional file 1: Table S3). Burkina Faso, Bangladesh, and Papua New Guinea were the three most dominant countries with disease incidence burden, compared to Belgium, Croatia and Canada, which were the three least dominant countries (Additional file 1: Table S9).

Paratyphoid fever

Oceania and South Asia had the highest ASIR, age-standardized DALY rate and ASMR for paratyphoid fever in 2021, exceeding 112.00 per 100,000 population, 25.00 per 100,000 population and 0.34 per 100,000 population, respectively (Table 4 and Additional file 1: Table S4). For paratyphoid fever, India, Pakistan, and Nepal had the highest ASIR, DALY rate and ASMR (Additional file 1: Table S9).

Diphtheria

Diphtheria had the most dominant ASIR in Oceania in 2021, up to 1.15 per 100,000 population (Table 5), but African areas, including Somalia, Central Africa Republic, and Nigeria were the top three ASIR countries. The most dominant age-standardized DALY rate was in Western sub-Saharan Africa, exceeding 215.00 per 100,000 population (Table 5 and Additional file 1: Table S9).

Pertussis

For pertussis, the top region of ASIR, age-standardized DALY rate and ASMR was Central sub-Saharan Africa, exceeding 475.00 per 100,000 population, 323.00 per 100,000 population and 3.72 per 100,000 population, respectively in 2021 (Table 6 and Additional file 1: Table S6). Among these regions, Angola, Central African Republic, and Somalia had the highest ASIR (Additional file 1: Table S9).

Tetanus

Tetanus had the highest ASIR, age-standardized DALY rate and ASMR in Eastern sub-Saharan Africa in 2021, exceeding 3.31 per 100,000 population, 96.46 per 100,000 population and 1.94 per 100,000 population respectively (Table 7 and Additional file 1: Table S7). Somalia and South Sudan were the two countries with the dominant ASIR and age-standardized DALY rate (Additional file 1: Table S9).

Leprosy

Leprosy was the most prevalent in Tropical Latin America, with the highest ASIR and age-standardized DALY rate compared to other regions (Table 8). Micronesia, Kiribati, and Marshall Islands had the highest incidence rate, and Kiribati, Tuvalu and Micronesia had the highest DALY rate. There were no death-related data reported for this disease (Additional file 1: Table S9).

Gender and age distribution for eight bacterial diseases

For syphilis, in the 50–54 age group, the specific incidence rate is higher in males than in females (P < 0.05), with no significant differences observed in other age groups (P > 0.05, equally). For leprosy, the specific incidence rate between males and females shows no significant difference in the 20–24 and 50–54 age groups (P > 0.05, equally), while in other age groups, males have a significantly higher incidence rate than females (P < 0.05). The specific incidence rates for gonococcal infection, typhoid and paratyphoid fever, diphtheria, pertussis, and tetanus show no differences between males and females across all age groups (P > 0.05, equally, Fig. 1A–H).

Fig. 1

Global number of incidence cases and the point incidence rates per 100,000 population of eight bacterial diseases, by age and sex in 2021. Syphilis (A), Gonococcal infection (B), Typhoid fever (C), Paratyphoid fever (D), Diphtheria (E), Pertussis (F), Tetanus (G), Leprosy (H)

In the 45–54, 60–64 age groups and above, the specific DALY rates for syphilis are higher in males than in females (P < 0.05), with no significant differences in other age groups (P > 0.05, equally). In the 10–24 and 50–54 age groups the specific DALY rates for gonococcal infection are higher in males than in females (P < 0.05), with no significant differences in other age groups (P > 0.05, equally). For leprosy, only in the > 95 age group, the specific incidence rate is higher in males than in females (P < 0.05), with no significant differences observed in other age groups (P > 0.05, equally). The specific DALY rate for other five diseases show no differences between males and females across all age groups (P > 0.05, equally, Additional file 2: Fig. S1A–H).

In the 45–49, 75–79, 85–89, and > 95 age groups, the specific mortality rate of syphilis is higher in males than in females (P < 0.05), with no significant differences in other age groups (P > 0.05, equally). The specific mortality rates for other diseases show no differences between males and females across all age groups (P > 0.05, equally, Additional file 2: Fig. S2A–G).

The specific DALY rate is highest in the < 5 age group for syphilis, typhoid, paratyphoid, diphtheria, pertussis, and tetanus. The specific incidence rate is highest in the < 5 age group for typhoid, paratyphoid, diphtheria, pertussis, and tetanus (Fig. 1A–H and Additional file 2: Fig. S1A–H).

Association between eight bacterial diseases burdens and SDI

Overall, the ASIR and age-standardized DALY rate had a decrease trend from 1990 to 2021 in five SDI regions classification for typhoid fever, paratyphoid fever, diphtheria, pertussis, tetanus, and leprosy globally (Fig. 2C–H and Additional file 2: Fig. S3C–H). From 1990 to 2021, the ASIR for syphilis had a decline trend with increase in the SDI globally. However, syphilis had an increasing ASIR from 2019 (224.31 per 100,000 population, 95% UI: 170.58, 288.58 per 100,000 population) to 2021 (235.47 per 100,000 population, 95% UI: 176.40, 307.63 per 100,000 population) globally (Fig. 2A and Additional file 2: Figs. S3A and S4A). For gonococcal infection, there was a fluctuated trend of ASIR from 1990 to 2021. The global ASIR of gonococcal infection was stable in 2021 (838.70 per 100,000 population, 95% UI: 838.70, 1385.47) compared to 2019 (1096.44 per 100,000 population, 95% UI: 839.31, 1387.21 per 100,000 population), whereas in low SDI regions, there was a slightly increase from 2019 to 2021 (Fig. 2B). For pertussis, a sharp decrease was shown from 2019 to 2021 for ASIR, ASMR and age-standardized DALY rate: for ASIR, from 304.50 per 100,000 population (95% UI: 235.39, 387.54 per 100,000 population) to 110.61 per 100,000 population (95% UI: 78.48, 156.93 per 100,000 population); for age-standardized DALY rate, from 179.72 per 100,000 population (95% UI: 86.16, 309.62 per 100,000 population) to 70.92 per 100,000 population (95% UI: 31.90, 142.08 per 100,000 population); for ASMR from 2.04 per 100,000 population (95% UI: 0.98, 3.53 per 100,000 population) to 0.81 per 100,000 population (95% UI: 0.36, 1.63 per 100,000 population, Fig. 2F and Additional file 2: Figs. S3F and S4F).

Fig. 2

Age-standardized incidence rates per 100,000 population of Syphilis (A), Gonococcal infection (B), Typhoid fever (C), Paratyphoid fever (D), Diphtheria (E), Pertussis (F), Tetanus (G) and Leprosy (H) from 1990 to 2021 by five SDI regions. SDI Socio-demographic Index

In 2021, ASIR of syphilis and pertussis showed a sharp decline with SDI increased, and typhoid fever and paratyphoid fever, diphtheria, tetanus, and leprosy had a slight decreasing trend with increasing SDI. ASIR of gonococcal infection kept stable first and then decreased with increasing SDI (Additional file 2: Fig. S5). There was a sharp decrease with rising SDI for age-standardized DALY rate in syphilis, gonococcal infection, pertussis, and leprosy, whereas there was a slight decrease for typhoid fever, paratyphoid fever, diphtheria, and tetanus (Additional file 2: Fig. S6). The ASMR of syphilis, gonococcal infection, and pertussis had a steeply inverse relationship with SDI, whereas typhoid fever, paratyphoid fever, diphtheria, and tetanus had a slightly negative correlation with SDI (Additional file 2: Fig. S7).

From 1990 to 2021, the ASIR, age-standardized DALY rate and ASMR for syphilis, diphtheria, pertussis, and tetanus declined rapidly with increases in SDI in 21 GBD regions globally (Additional file 2: Fig. S8, AEFG & S9, AEFG & S10, AEFG). However, these trends varied across different GBD regions. The ASIR, ASMR and age-standardized DALY rate for syphilis increased and then decreased with rising SDI in Central sub Saharan Africa, whereas was stable in North Africa and Middle East, Central Europe, high-income Asia Pacific, and Eastern Europe (Additional file 2: Figs. S8A, S9A and S10A). The ASIR of gonococcal infection was relatively stable in all GBD regions except for Southern sub-Saharan Africa and Oceania (increased and then decreased with increasing SDI). By contrast, age-standardized DALY rate and ASMR of gonococcal infection decreased globally with rising SDI (Additional file 2: Fig. S8B, S9B and S10B). The ASIR, ASMR, and age-standardized DALY rates for typhoid fever and paratyphoid fever declined sharply with increasing SDI in South Asia, Southeast Asia, and Central sub-Saharan Africa (Additional file 2: Figs. S8CD, S9CD and S10CD). The ASIR, age-standardized DALY rate and ASMR for diphtheria decreased with rising SDI in Western sub-Saharan Africa, South Asia, and Southeast Asia, whereas East Asia, Western Europe and Australasia kept stable with rising SDI (Additional file 2: Figs. S8E, S9E and S10E). The ASIR of pertussis in high-income Asia Pacific decreased with rising SDI, whereas the age-standardized DALY rate of pertussis in Caribbean declined swiftly with increasing SDI, reached a bottom, and then increased sharply with further increases in SDI (Additional file 2: Figs. S8F and S9F). The ASIR, age-standardized DALY rate and ASMR of tetanus in South Asia, Southeast Asia, Central sub-Saharan Africa decreased sharply (Additional file 2: Figs. S8G, S9G and S10G). The ASIR and age-standardized DALY rate of leprosy in South Asia and Central sub-Saharan Africa decreased with rising SDI, while North Africa and Middle East kept stable with rising SDI (Additional file 2: Figs. S8H and S9H).

Variance analysis in 21 geographic regions of the globe

In 2021, globally, among the eight bacterial infections, the top three diseases with the highest ASIR were gonorrhea, syphilis, and pertussis; the top three diseases with the highest age-standardized DALY rate were syphilis, typhoid, and pertussis; and the top three diseases with the highest ASMR were typhoid, syphilis, and pertussis (Fig. 3A–C). The ASIR of typhoid fever was notably higher in South Asia compared to other GBD regions. Typhoid and paratyphoid fever showed relatively higher DALY rates in South Asia and Oceania. (Fig. 3A–B).

Fig. 3

Heatmap of eight specific bacterial infections in 21 GBD regions in 2021. Age-standardized incidence rate (A), age-standardized DALY rate (B), and age-standardized mortality rate per 100,000 population (C). DALY: disability-adjusted life year, GBD Global Burden of Disease