Diarrhea analysis
DALISO NGULUBE
2025-10-14
Background
Diarrhea is characterized by the passage of three or more liquid stools within a 24-hour period. Various etiological agents can cause diarrhea, including viral, bacterial, and protozoan organisms. The condition can be classified as acute watery, lasting less than 14 days, or persistent, lasting more than 14 days and often resulting in weight loss and nutritional problems. The duration of diarrhea depends on the causal agent. Diarrhea is more prevalent in developing countries due to inadequate access to safe drinking water, sanitation, and hygiene. Effective treatment involves simple case management with oral rehydration therapy. If left untreated, diarrhea can lead to death due to excessive loss of water and electrolytes in the stool.
In Zambia, diarrheal disease data is routinely collected through the electronic Integrated Disease Surveillance and Response system. However, detailed analysis is often lacking, particularly at the sub-national and district levels. While summary statistics are compiled across districts, detailed analysis and action threshold levels are not established to inform targeted interventions. This gap in analysis denies public health officials valuable insights necessary for effective monitoring, control, and prevention of diarrheal disease. To address this, we conducted a descriptive analysis of diarrheal surveillance data to identify patterns and establish threshold levels across all provinces in Zambia, ultimately aiming to enhance disease control measures.
Methods
Study Design
A retrospective descriptive analysis was conducted on weekly aggregate diarrhea data reported from January 2019 to September 2025. The data was collected from the electronic Integrated Disease Surveillance and Response (eIDSR) system, a database for all priority conditions reported by health facilities nationwide.
Variables Analyzed
Variables such as age group and region were analyzed.
Study Period
This study is ongoing and expected to be concluded by October 20, 2025.
Data Collection, Processing, and Analysis
Diarrhea surveillance data from January 2019 to September 2025 was collected from the eIDSR system across all ten provinces. The data was exported to Microsoft Excel 2019 and cleaned and analyzed descriptively using R software. The data was summarized in terms of frequencies and proportions and presented in terms of time, place, and person.
Threshold Calculation
Thresholds for diarrhea were calculated using the C2 method, defined as the sum of the mean and three standard deviations of the seven preceding monthly diarrhea cases, skipping the two most recent months.
Results
Basic characteristics of the suspected cases
Between January 2019 and September 2025, a total of 6,171,601 suspected cases of non-bloody diarrhea were reported across all provinces. Notably, children under 5 years (0-4 years) accounted for 45% (2,797,048/6,171,601) of the cases. The provinces with the highest number of reported cases were Eastern (15%, 913,657/6,171,601) and Southern (15%, 909,835/6,171,601), while Muchinga province reported the lowest number of cases during the review period.
| Characteristic | Overall N = 6,171,0611 |
2019 N = 677,3871 |
2020 N = 751,0591 |
2021 N = 648,6921 |
2022 N = 535,7121 |
2023 N = 997,9881 |
2024 N = 1,388,5861 |
2025 N = 1,171,6371 |
|---|---|---|---|---|---|---|---|---|
| AgeGroup | ||||||||
|     ≥ 15 years | 2,206,549 (36%) | 239,344 (35%) | 272,744 (36%) | 231,694 (36%) | 185,193 (35%) | 344,207 (34%) | 499,087 (36%) | 434,280 (37%) |
| Â Â Â Â 0-4 years | 2,797,048 (45%) | 265,210 (39%) | 328,529 (44%) | 292,965 (45%) | 244,345 (46%) | 474,613 (48%) | 650,353 (47%) | 541,033 (46%) |
| Â Â Â Â 5-14 years | 1,167,464 (19%) | 172,833 (26%) | 149,786 (20%) | 124,033 (19%) | 106,174 (20%) | 179,168 (18%) | 239,146 (17%) | 196,324 (17%) |
| Province | ||||||||
| Â Â Â Â Central | 845,354 (14%) | 90,895 (13%) | 102,208 (14%) | 94,283 (15%) | 110,481 (21%) | 128,749 (13%) | 171,680 (12%) | 147,058 (13%) |
| Â Â Â Â Copperbelt | 809,008 (13%) | 103,444 (15%) | 79,767 (11%) | 90,038 (14%) | 99,986 (19%) | 112,830 (11%) | 166,302 (12%) | 156,641 (13%) |
| Â Â Â Â Eastern | 913,657 (15%) | 84,370 (12%) | 97,499 (13%) | 95,412 (15%) | 79,346 (15%) | 150,835 (15%) | 215,868 (16%) | 190,327 (16%) |
| Â Â Â Â Luapula | 379,012 (6.1%) | 41,020 (6.1%) | 61,684 (8.2%) | 52,284 (8.1%) | 31,918 (6.0%) | 63,116 (6.3%) | 76,387 (5.5%) | 52,603 (4.5%) |
| Â Â Â Â Lusaka | 517,954 (8.4%) | 65,895 (9.7%) | 37,878 (5.0%) | 33,628 (5.2%) | 41,460 (7.7%) | 89,058 (8.9%) | 129,219 (9.3%) | 120,816 (10%) |
| Â Â Â Â Muchinga | 190,167 (3.1%) | 3,106 (0.5%) | 22,539 (3.0%) | 28,511 (4.4%) | 13,151 (2.5%) | 38,480 (3.9%) | 49,014 (3.5%) | 35,366 (3.0%) |
| Â Â Â Â North-Western | 590,201 (9.6%) | 64,282 (9.5%) | 95,329 (13%) | 54,108 (8.3%) | 29,101 (5.4%) | 96,943 (9.7%) | 139,493 (10%) | 110,945 (9.5%) |
| Â Â Â Â Northern | 450,317 (7.3%) | 46,281 (6.8%) | 70,749 (9.4%) | 53,691 (8.3%) | 34,039 (6.4%) | 83,038 (8.3%) | 90,507 (6.5%) | 72,012 (6.1%) |
| Â Â Â Â Southern | 909,835 (15%) | 141,889 (21%) | 116,678 (16%) | 100,976 (16%) | 62,705 (12%) | 135,851 (14%) | 197,576 (14%) | 154,160 (13%) |
| Â Â Â Â Western | 565,556 (9.2%) | 36,205 (5.3%) | 66,728 (8.9%) | 45,761 (7.1%) | 33,525 (6.3%) | 99,088 (9.9%) | 152,540 (11%) | 131,709 (11%) |
| 1 n (%) | ||||||||
Trends of diarrhoea cases across all the provinces, January 2019 to September 2025
- Cases have been on the increase since 2022
## Warning: Using `size` aesthetic for lines was deprecated in ggplot2 3.4.0.
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Trends of diarrheal cases with C2 threshold across Provinces January 2019- September 2025
- over time, several possible outbreaks were observed with the latest seen in September 2025
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provincial picture
- A number of provinces show points of potential outbreaks
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Analysis by provinces
Analysis by district
- A number of districts had possible outbreaks over time
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next steps
overlay data for cholera outbreaks and excess mortality
Discuss the findings and propose recommendations