Intestinal parasites in commercial vegetables in the city of Maputo, Mozambique: is it a public health concern?

In developing countries such as Mozambique, markets are the main supplier of horticultural products to populations, but this can pose a public health challenge due to the risk of fecal-oral transmission of gastrointestinal pathogens. The transmission of gastrointestinal parasitic pathogens can occur through water, soil, and food such as contaminated fresh fruits and vegetables (when eaten raw/unwashed), shellfish, fish, and meat when improperly cooked. This transmission is associated to inadequate public sanitation and low standards of personal and community hygiene, resulting in gastrointestinal diseases, which are the third leading cause of mortality in Mozambique in children under 5 years of age. The objectives of this study are: to evaluate the occurrence of intestinal parasites, focusing on Giardia duodenalis, Cryptosporidium spp. and Enterocytozoon bieneusi in fresh horticultural products for human consumption; and analyze the supply chain, from the production zone to municipal markets. The analysis of the data obtained will enable the elaboration of suggestions for market management tools in order to improve their operation and prevent early contamination of fresh products in markets in the city of Maputo. In four (4) chapters, we intend: 1) to determine the degree of knowledge and attitude of vendors of fresh horticultural products and about the facilities and environment of the markets; 2) to investigate the occurrence of intestinal parasites in fresh horticultural products sold in Maputo city markets; 3) to characterize with molecular techniques G. duodenalis and E. bieneusi detected here; 4) to better understand the processes of the food supply chain (FSC) in Maputo city, and all the interactions of those involved in this chain until the product reaches the final consumer, and provide tools for efficient management. Eight (8) sampling sites were strategically chosen: two (2) supermarkets, five (5) municipal markets including the wholesale and one (1) producer zone, in dry and rainy seasons. To characterize the markets, their dynamics, vendors’ attitude and field knowledge, interviews, questionnaires and observational analysis were applied.
Laboratory parasitological and molecular techniques were used to identify and characterize the parasites found in the analyzed samples. By microscopy, it was possible to identify Giardia duodenalis, Balantidium coli, Entamoeba histolytica, Blastocystis spp., Strongyloides stercoralis, Nematodes and helminths in general, and the commensal species of protozoa Chilomastix mesnili, Entamoeba coli, Endolimax nana and Iodamoeba bustchiili. By polymerase chain reaction (PCR) it was possible to detect DNA of G. duodenalis and Enterocytozoon bieneusi in 2.8% (9/321) and 1.3% (4/321) of the samples monitored, respectively. Cryptosporidium spp. was not identified or detected by any of the methodologies utilized. The molecular characterization of G. duodenalis resulted in four different sequences (three novel and one known) all from Assemblage B and, the molecular characterization of E. bieneusi revealed three different sequences (two novel and one known) belonging to group 1. The results of the molecular characterization, highlight the high potential for zoonotic transmission of pathogenic intestinal parasites, corroborating their potential role as a source of human infection and environmental contamination. This is the first time that intestinal parasites are characterized in fresh horticultural products in Maputo markets, in Mozambique.
The results obtained in this study showed that while Maputo markets are struggling to achieve quality hygiene standards reliably and sustainably, their resources are limited and the attitude of vendors reflects their lack of knowledge in good hygiene practices (GHP). It also revealed a favorable environment for the occurrence of contamination of fresh products for sale by pathogenic intestinal parasites. This contamination is enhanced by the lack of clean and organized sanitary facilities, exposure to biological contaminants and poor conservation of fresh products, especially in the dry seasons, when the occurrence of parasites is higher. The lack of good hygiene practices (GHP) revealed by vendors and other operators in the different stages of the food supply chain (FSC) opens gaps in this system, leading to the maintenance of a deficient FSC and consequently unreliable for consumers. Thus, we suggest: a multisector management approach involving standardized procedures for each stage of the FSC; “one way” circuit of vehicles; better coordination for municipal entities; water supply system and sanitation improvements; processing map implementation; mandatory measures for hygiene on daily work; regular training in GHP. These measures will contribute to reducing the degree of contamination of food in the early stages and throughout the FSC process, resulting in safer and more reliable products, and minimizing the problems associated with public health.
This is the first study on the contamination of horticultural products by intestinal parasites, for human consumption, in markets in Maputo, Mozambique, and points out steps towards understanding the causes of this contamination with the ultimate objective of its control and elimination. This study also opens new perspectives on the epidemiology and transmission routes of G. duodenalis and E. bieneusi in water, food and clinical areas. A better understanding of these intestinal parasitic organisms highlights the importance of monitoring the hygienic conditions to which agricultural products are exposed in markets in the Maputo region, as they can become a public health problem mainly for vulnerable people, such as children, pregnant women, the elderly and immunosuppressed. Finally, in the future it will be necessary to measure the performance of the implementation of the improvements proposed in this study. This measurement will provide information on the responsiveness to new processes after their application.