Reservoirs of Cryptosporidium and Giardia in Africa

Abstract

Cryptosporidium and Giardia are the most commonly identified waterborne protozoan pathogens. Although they are responsible for waterborne outbreaks globally (Baldursson and Karanis 2011), the highest burden of disease from Cryptosporidium and Giardia is in developing countries, including those in Africa (Feng and Xiao 2011; Bouzid et al. 2018). These pathogens may be transmitted by contaminated drinking water, recreational water, and treated and untreated wastewater (Ongerth and Karanis 2018). Other transmission routes include contaminated food, usually from infected food handlers or food irrigated with contaminated water (Carmena 2010). In Africa, Cryptosporidium and Giardia infections are prevalent among communities that lack access to clean potable water supplies. Over 300 million people in sub-Saharan Africa are without access to safe drinking water (WHO 2015). Surface waters, often polluted due to uncontrolled sewage discharge, poorly managed wastewater treatment plants (Dungeni and Momba 2010), and inadequate waste disposal facilities from settlements located close to rivers (Uneke and Uneke 2007), thus form alternative, if not the only water source available within many countries on the continent. The sub-Saharan African population lacking access to sanitation has increased since 1990, influenced by rapid population growth and slow progress in attaining sanitation targets (WHO 2015). Unsafe water supplies and inadequate sanitation and hygiene conditions increase the transmission of diarrheal diseases such as Cryptosporidium and Giardia. In addition to the challenges that Africa faces regarding unsafe water supplies, the prevalence of HIV and malnutrition also predisposes communities to the diarrheal diseases caused by these parasites.