# Quantifying the population-level impact of expanded antibiotic treatment for cholera outbreak management

## TL;DR

This study uses a mathematical model to explore how expanding antibiotic use for cholera could reduce outbreaks, but warns about antibiotic resistance risks.

## Contribution

A novel compartmental model quantifies the impact of expanded antibiotic treatment on cholera transmission and antibiotic resistance risks.

## Key findings

- Expanding antibiotic treatment can significantly reduce outbreak size under certain conditions.
- Treating non-severe cases with antibiotics may decrease transmission and total antibiotic use in some scenarios.
- Effectiveness depends on high care-seeking rates and outbreak-specific conditions.

## Abstract

Since 2021, there has been a resurgence in the number of cholera cases, countries affected, and the case fatality rate. Because most cholera patients recover without antibiotic treatment, current cholera treatment guidelines only consider the tradeoffs between patient recovery and antibiotic stewardship. However, antibiotics also greatly reduce bacteria shedding, creating a potential role for antibiotics in cholera outbreak response through reduced transmission. We developed a compartmental model of cholera transmission in a non-endemic setting to quantify the potential impact of expanded antibiotic treatment on disease burden and antibiotic use. Through simulations, we evaluated different outbreak scenarios, by varying the reproductive number, care-seeking behavior, and proportion of non-severe cases receiving antibiotics. We found that expanding antibiotic treatment could significantly reduce the final outbreak size under certain outbreak characteristics. In these scenarios, treating non-severely symptomatic infections with antibiotics decreased cholera transmission and, in some cases, the total number of antibiotic doses used. We show that the effectiveness of expanded antibiotic treatment is highly dependent on achieving high care-seeking rates among non-severely symptomatic infections and tailoring the approach to specific outbreak conditions. While expanding antibiotic eligibility could enhance outbreak control in some settings, careful consideration of antibiotic resistance risks is necessary in high-transmission contexts.

Cholera remains a dangerous infectious disease in many parts of the world, with more deaths occurring in more countries in recent years. Most people recover from cholera with simple rehydration. For high-risk and severe cases, antibiotics are used to clear the infection faster. Without antibiotics, people can continue to shed cholera bacteria even after they feel better. Antibiotics stop this bacterial shedding, which decreases how much bacteria is spreading in the community. However, the more antibiotics are used, the greater the likelihood that cholera develops antibiotic resistance, which would make antibiotics no longer an effective treatment. In this study, we use a mathematical model to test two antibiotic prescribing scenarios: a) the current guidelines of antibiotics only for high-risk/severe patients, and b) prescribing antibiotics to more cholera patients, with the idea that this will lead to less spreading of cholera and fewer cases overall. We show treating more types of patients (severely and moderately ill) with antibiotics can lead to smaller outbreaks and fewer doses of antibiotics prescribed under certain outbreak conditions. We also show which parts of the model are most important, and highlight areas that need more scientific research before we can be confident in our results.