Addressing Food Safety in Aquaculture Systems in Developing Countries
This post is written by Mohammad Aminul Islam and originally appeared on the Feed the Future Innovation Lab for Fish website. Islam is the lead principal investigator of the Feed the Future Innovation Lab for Fish project on identifying major sources of fecal pathogens in the Bangladeshi aquaculture value chains. Islam is an assistant professor for the Paul G. Allen School for Global Animal Health at Washington State University.
Foodborne diseases (FBDs), caused by ingesting food contaminated with hazards, is a significant source of morbidity and mortality around the world. The major cause of FBD is consumption of foods that are contaminated with microbial pathogens, parasites, chemical contaminants and biotoxins. Among microbial pathogens, the most frequent are Salmonella spp (predominantly non-typhoidal Salmonella enterica), Campylobacter jejuni, norovirus, Vibrio cholerae, Vibrio parahaemolyticus and diarrhoeagenic Escherichia coli.
Globally, over 600 million people, one in 10, suffers from FBD each year, and 420,000 people died from them in 2010. The number of deaths and disability combined contributes to an estimated 33 million disability-adjusted life years (DALYs). Children under 5 years of age are at the highest risk, comprising 30% of the total foodborne deaths annually. Diarrhea, most commonly resulting from contaminated food, kills 2,195 children every day — more than AIDS, malaria and measles combined. Around 98% of the global burden of FBD falls on low- and middle-income countries (LMICs), and the highest burden of FBD is estimated to be in Asia.
As average incomes increase and customers demand higher value agriculture, this also increases the risk of FBDs, since the most nutritious foods (animal-source food and fresh vegetables) are often the most implicated, especially in transitioning countries. The value chains of high-value agriculture foods are often very complex. Thus, FBDs are likely to increase in LMICs unless capacity to reduce prevalence and infrastructure to monitor such value chains are introduced.
Taking aquaculture systems as an example, this sector in LMICs has been rapidly growing as demand for aquaculture products has been rising. An estimated 56% of the world's population obtains at least 20% of their animal protein intake from finfish and shellfish. Modern aquaculture facilities rely heavily on intensified cultivation systems with the supply of formulated feeds and the application of various agrochemicals, including antibiotics. In many places, antibiotics or other agrochemicals are mixed with fish feed to ensure the health of the fish population. In addition, in most Asian countries, such as China, Bangladesh, India, Indonesia and Vietnam, there is a long history of using wastewater (particularly animal waste) in fish ponds.
While wastewater-fed aquaculture systems provide high fish yield, the use of excreta in aquaculture systems has the potential to harbor microbial pathogens and negatively impact human health. Fish raised in wastewater-fed ponds harbor pathogens from feces in their scales, gills, digestive tracts and muscle tissue.
Antimicrobial resistance is an emerging problem in intensified aquaculture systems and in integrated fish and poultry farming systems, both of which are popular in LMICs. As the fish move along the value chain from capture to processing, there is the potential for pathogens on the fish to transfer to the surfaces of handling equipment and people when rinsing and storing the fish.
In Bangladesh, fish farming is currently one of the most important sectors of the national economy. Fish is the most culturally preferred food after rice among Bangladeshi population, providing around 80% of the animal protein intake. However, aquaculture in the country has suffered from food safety issues due to microbial contamination, which harmed both the health of domestic consumers and the country’s access to international markets. Apart from primary contamination in ponds, fish in the domestic market can be contaminated with microbial pathogens at various stages of the supply chain. At the retail markets, most buyers take freshly-bought fish to a merchant who cuts and cleans the fish, often under unhygienic conditions. Because of the large number of actors, it is difficult to regulate and ensure the safety of the product at each step of the process.
In our Feed the Future Innovation Lab for Fish project, we are assessing the entire supply chain of the two most-consumed fish by the local people in Bangladesh — tilapia and pangas — for contamination with major foodborne pathogens. Additionally, we are analyzing stakeholders’ behavioral practices at every stage of the supply chain that can contribute to the contamination of fish at the consumer's point. We will use this data to develop a quantitative microbial risk assessment model and identify critical points for implementing future intervention strategies. Our study will provide science-based decisions on the most effective methods and key actors/locations to intervene to reduce microbial contamination of fish in informal markets of Bangladesh, which is an important step toward addressing food safety in aquaculture systems in the country.
FBDs are preventable. Effective intervention strategies targeting both consumers and food supply chains need to be developed following risk-based approaches that are most relevant to the local context. Risk assessment should be backed up by data from systematic surveillance of major foodborne pathogens along the food production and supply chain. Involvement of multidisciplinary stakeholders from human, animal and environmental sectors is essential for successful implementation of food safety interventions in LMICs.