The Importance of Maintenance: Geospatial Analysis of Cholera Risk and Water and Sanitation Infrastructure in Harare, Zimbabwe

# Introduction

The World Health Organization’s (WHO’s) Global Task Force on Cholera Control views cholera not just as a global threat to public health, but also an indicator of poverty and a mark of inequity[1]. Since 1970, cholera has become endemic in many countries in Sub-Saharan Africa [2] with annual case fatality ratios (CFRs) of 1.6% - the highest in the world [3]. While several oral cholera vaccines (OCVs) now exist, they only protect against cholera infection for up to two years, and they address the symptoms and not the cause. Large outbreaks continue to plague several countries, especially in Sub-Saharan Africa. Without addressing the pathways to contamination in these low-income settings with inadequate infrastructure, outbreaks will continue to be a risk.

Pathways for transmission can include contaminated water sources, both for drinking and domestic use [4][5], [6][7], poor sanitation [8][9][10]; contaminated food, poor personal hygiene [11] and poor drainage [11], [12]. These same pathways can also lead to other water-borne diseases such as typhoid, making it vital to understand which pathways are most important in a given setting in order to target resources effectively to reduce the spread of these diseases. Additionally, since cholera is a water-borne disease, the focus in terms of risk factors is usually on infrastructure and water sources, yet another important factor is mobility. If infected individuals travel from an area with a cholera outbreak to an area without any cases and the water/sewer networks are susceptible to contamination, the traveler could contaminate the water in this new location and lead to the spread of the disease [[13], [14]]. Studying the role of mobility could be important for helping to contain spread [15]–[17].

In particular, outbreaks in developing country contexts are usually attributed to where households have low access to WHO Joint Monitoring program classified ‘improved’ water and sanitation infrastructure such as networked water and sewer systems [2], [18 <mark>]. However, poorly maintained or operated network infrastructure can also fail to bring about the protection from cholera that it may seem to promise. There are examples from developed and middle-income countries where poor operation of sewerage infrastructure can lead to health and environmental hazards</mark> [19]–[21].

An understanding of the spatial distribution of cholera risk, and the factors driving risk, can support decision making around longer-term interventions to reduce the risk of outbreaks. Especially in cities with mixed service provision - where households may rely on piped water and point sources for drinking water, and on site sanitation or sewer networks for sanitation - there are a variety of potential improvements that could be made. These range from investing in repair or construction of network infrastructure (water or sewer pipes), to ensuring better access to protected point sources (boreholes, protected wells) or improving the quality of on-site sanitation (such as pit latrines or septic tanks). While in general, improving access to piped water is considered an improvement in infrastructure with public health benefits, piped water networks can become health 2