The incidence trend of natural focal disease
The incidence of natural focal diseases was high between September and December each year, with an increasing trend from September and a decreasing trend after reaching its peak in November (Fig. 1). The incidence in November 2015, 2016, 2017, 2018 and 2019 reached 15.29, 12.10, 8.98, 9.49 and 16.11 (per 1,000,000 people) respectively. And the incidence in February 2020 (0.40 per 1,000,000 people) was lower than that in the same period during the previous four years (range: 0.65–0.95 per 1,000,000 people); the incidence in March 2020 (0.40 per 1,000,000) was lower than that in the same period in the previous four years (range: 0.60–1.05 per 1,000,000 people); the incidence in April 2020 (0.47 per 1,000,000) was lower than that in the same period for the previous four years (range: 0.64–1.01 per 1,000,000 people).
The monthly distribution of natural focal disease
The incidence of January to April, 2020 was compared with the year from 2015 to 2019 (Fig. 2). The results showed that the incidence of brucellosis ranged from 0.5 to 3.1 (per 10,000,000 people) in February 2015–2019, while the incidence decreased to 0.3 (per 10,000,000 people) in February 2020. As for malaria, the incidence in February 2015–2019 ranged from 1.6 to 4.5 (per 10,000,000 people), while reduced to 0.9 (per 10,000,000 people) in February 2020; the incidence in March 2015–2019 ranged from 0.8 to 3.3 (per 10,000,000 people), while reduced to 0.3 (per 10,000,000 people) in March 2020; the incidence ranged from 1.0to 2.9 (per 10,000,000 people) in April from 2015–2019, while in April 2020, the incidence was dropped to 0.1(per 10,000,000 people). We also found that the incidence of HF ranged from 1.4 to 2.6 (per 10,000,000 people) in March from 2015 to 2019, while the incidence decreased to 1.0 (per 10,000,000 people) in March 2020. The incidence of SFTS in March, 2015–2019 ranged from 0 to 0.1 (per 10,000,000 people), while the incidence of SFTS increased to 0.3 (per 10,000,000) in March 2020. Moreover, the incidence of dengue, rabies, tsutsugamushi and JE in January-April 2020 were all within the range of previous years.
Distribution of duration from onset to date of diagnosis (DID) for natural focal diseases
The inter-quartile range (IQR) from January to April 2020 with January to April 2015/2016/2017/2018/2019 was compared. The results showed that the IQR of brucellosis, malaria and HF were still within the range as those during the same period for the previous four years. The IQR of Brucellosis from January to April 2020 was statistically different from that of 2015 and 2017 (P < 0.05). The IQR of malaria and HF from January to April 2020 showed no statistically difference compared with the IQR of the previous four years (Table 1).
Table 1
Distribution of duration from onset of illness to date diagnosis for brucellosis, malaria and HF, Jiangsu Province, China, January to April, 2015–2020
Year
|
IQR(days)
|
Brucellosis
|
Malaria
|
HF
|
2015
|
11–57*
|
1–4
|
4–9
|
2016
|
4–61
|
2–4
|
4–9
|
2017
|
8–44*
|
2–6
|
4–11
|
2018
|
7–32
|
2–5
|
2–9
|
2019
|
1–23
|
2–4
|
3–9
|
2020
|
1–29
|
1–4
|
2–10
|
IQR inter-quartile range |
*P values have statistical significance. |
The regional distribution of COVID-19, brucellosis, malaria and HF
Figure 3-A showed that the incidence of COVID-19 was high in Huai’ an City (13.60 per 1,000,000 people), Nanjing City (11.74 per 1,000,000 people) and Changzhou City (11.21 per 1,000,000 people); the incidence of COVID-19 was low in Suqian City (3.05 per 1,000,000 people), Zhenjiang City (3.75 per 1,000,000 people) and Yancheng City (3.89 per 1,000,000 people).
The results also showed that the incidence of natural focal diseases (brucellosis, malaria and HF) in Wuxi city ranged from 0.14 to 0.60 (per 1,000,000 people) and 0.15 to 0.45 (per 1,000,000 people) in January and February from 2015 to 2019 respectively, but dropped to 0 (per 1,000,000 people) in January and February 2020; the incidence of natural focal diseases (brucellosis, malaria and HF) in Taizhou city and Yangzhou city ranged from 0.21 to 0.86 (per 1,000,000 people) and 0.44 to 0.89 (per 1,000,000 people) respectively in March 2015–2019, but dropped to 0 (per 1,000,000 people) in March 2020; the incidence of natural focal diseases (brucellosis, malaria and HF) in Nantong city ranged from 0.41 to 1.23 (per 1,000,000 people) in April, 2015–2019, but dropped to 0 (per 1,000,000 people) in April 2020 (Figure 3-B).
The gender distribution brucellosis, malaria and HF
In males, the incidence of brucellosis (Fig. 4-A) in January (0.49 per 100,000,000 people), February (0.49 per 10,000,000 people) and April (0.74 per 100,000,000 people) 2020 less than the lower limit for range of January (0.50–3.23 per 100,000,000 people), February (1.00-3.96 per 100,000,000 people) and March (1.00-5.47 per 100,000,000 people) from 2015 to 2019 respectively. The incidence of malaria (Fig. 4-C) in February (3.70 per 100,000,000 people), March (1.97 per 10,000,000 people) and April (0.74 per 100,000,000 people) 2020 less than the lower limit for range of February (4.97–10.21 per 100,000,000 people), March (3.21–9.47 per 100,000,000 people) and April (4.21–7.23 per 100,000,000 people) from 2015 to 2019 respectively. The incidence of HF (Fig. 4-E) in March (1.23 per 100,000,000 people) and April (0.98 per 100,000,000 people) 2020 less than the lower limit for range of March (1.99–4.98 per 100,000,000 people) and April (1.48–3.21 per 100,000,000 people) from 2015 to 2019 respectively.
However, the incidence of all the natural focal diseases in females were within the same range as of during previous four years (Fig. 4-B, D, F).
The age distribution of brucellosis, malaria and HF
We found that the incidence of brucellosis (Fig. 5) in the age group 20–30 years in March 2020 (0 per 100,000,000 people) was lower than that during the same period of the previous four years (range: 0.72–2.19 per 100,000,000 people); the incidence in the age group 30–40 years in February 2020 (0 per 100,000,000 people) was lower than that during the same period of the previous four years (range: 0.85–2.88 per 100,000,000 people); the incidence in the age group 50–60 years in January (0 per 100,000,000 people), February (0.81 per 100,000,000 people) and March (0.81 per 100,000,000 people) 2020 less than the lower limit for range of January (0.97–4.79 per 100,000,000 people), February (0.95–6.80 per 100,000,000 people) and March (2.85–5.74 per 100,000,000 people) from 2015 to 2019 respectively. The incidence in the age group ≥ 60 years in February 2020 (0.60 per 100,000,000 people) was lower than that during the same period of the previous four years (range: 1.37–6.18 per 100,000,000 people).
The results showed that the incidence of malaria (Fig. 6) in the age group of 20–30 years in March 2020 (0.85 per 100,000,000 people) was lower than that during the same period of the previous four years (range: 1.44–2.92 per 100,000,000 people); the incidence in the age group 30–40 years in February (0.85 per 100,000,000 people), March (0.85 per 100,000,000 people) and April (0.85 per 100,000,000 people) 2020 less than the lower limit for range of February (2.88–9.53 per 100,000,000 people), March (2.88–12.39 per 100,000,000 people) and April (1.94–3.88 per 100,000,000 people) from 2015 to 2019 respectively; the incidence in the age group of 40–50 years in April 2020 (0.74 per 100,000,000 people) was lower than that during the same period of the previous four years (range: 3.25–10.82 per 100,000,000 people); the incidence in the age group of 50–60 years in April 2020 (0 per 100,000,000 people) was lower than that during the same period of the previous four years (range: 3.24–6.80 per 100,000,000 people).
The results showed that the incidence of HF (Fig. 7) in the age group 20–30 years in March 2020 was lower than that in the same period previous four years (range: 0.72–1.46 per 100,000,000 people); the incidence in the age group of 30–40 years in February 2020(0 per 100,000,000 people) was lower than that during the same period of the previous four years (range: 0.95–3.84 per 100,000,000 people); the incidence in the age group of 40–50 years in January 2020(2.21 per 100,000,000 people) was lower than that during the same period of the previous four years (range: 3.20–5.18 per 100,000,000 people).
Urban and rural distribution of brucellosis, malaria and HF
About brucellosis (Fig. 8-A),in urban, the number of cases in February 2020 (1 case) was within the range of that during the same period of previous four years (range: 1–12 cases); the number of cases in March 2020 (2cases) was within the range of that during the same period of previous four years (range: 2–17 cases). In rural, the number of cases in February 2020 (1 case) was lower than that during the same period of previous four years (range: 2–16 cases).
As for malaria (Fig. 8-B), in urban, the number of cases in March 2020 (2 cases) was within the range of that during the same period of previous four years (range: 2–17 cases). In rural, the number of cases in February 2020 (1 case) was lower than that during the same period of previous four years (range: 2–16 cases).
About HF (Fig. 8-C), in the urbans, the number of cases in March 2020(3 cases) was within the range for cases obtained during same period for the previous four years (range: 4–9 cases). In rural areas, the number of cases in January 2020 (11 cases) was lower than that documented during the same period for the past four years (range: 16–27 cases).