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*By Vivek Chauhan, Arya Singh, Shyni K, Shashank Singh
Foodborne pathogens are biological organisms that have the potential to cause illnesses through food. When compared to other animal protein sources, seafood is seen to be a healthier option. However, eating spoiled seafood is a leading cause of mortality and hospital admission, especially in emerging and impoverished nations. Therefore, this article discusses the various illnesses that might affect seafood as well asprevention procedures.
Introduction
Foodborne pathogens are biological organisms (bacteria, viruses, and parasites) that have potential to cause illnesses through food. When compared to other animal protein sources, seafood is seen to be a healthier option. Due to their abundance in omega-3 fatty acids, vitamin D, selenium, and iodine, they also provide additional health advantages (Mahaffey et al., 2008).
It has been demonstrated that seafood protects against cardiovascular disease and improves brain, vision, and cognitive development in new-borns and young children (Emmett et al., 2013). Eating spoiled seafood is a leading cause of mortality and hospital admission, especially in emerging and impoverished nations. Therefore, this article discusses the various illnesses that might affect seafood as well as prevention procedures.
Bacterial Infections
Vibrio spp
Numerous Vibrio sp are being identified as the reasons of foodborne illnesses. Gram-negative, rod-shaped, curved, non-spore-forming, motile, facultative anaerobic bacteria are the characters of genus Vibrio. The three pathogenic species that are most probable to infect humans are Vibrio cholerae, V. parahaemolyticus, and V. vulnificus. When individuals eat undercooked or raw diseased fish, there is a significant risk of microbiological dangers to human health that can result in illnesses related to seafood (Scallan et al., 2011). According to Scallan et al. (2011), this bacteria was the cause of around 96 illnesses, 91 hospitalizations, and about 35 fatalities in the US per year.
Listeria monocytogenes
Several outbreaks have been linked to the consumption of seafood contaminated with L. monocytogenes, which is responsible for 4% of global product detentions due to bacterial contamination (Gudmundsdottir et al., 2006). Listeriosis, a foodborne illness caused by Listeria species and associated with seafood, can be transmitted to humans through the consumption of packaged seafood products (Miya et al., 2010).
Symptoms of listeriosis include chills, nausea, fever, and gastroenteritis, and can escalate to more severe conditions like septicemia, meningitis, encephalitis, abortion, and even death (Barbuddhe et al., 2008). Pregnant women, individuals with weakened immune systems, and the elderly are at a higher risk of contracting listeriosis (Parihar et al., 2008).
Salmonella spp
Salmonella are facultative anaerobic Gram-negative bacteria with a rodlike structure. The symptoms begin 12–72 hours after consuming infected food and include diarrhea and mild to severe intestinal inflammation. In the US, it is the second most common cause of foodborne illness. Between 1973 and 2006, the intake of seafood was linked to 18 outbreaks of Salmonella, which resulted in 374 recorded cases of sickness and 28 hospitalizations in the United States (Iwamoto et al., 2010). Salmonellosis can be contracted by consuming raw or undercooked shellfish, mollusks, and crustaceans. Salmonella spp. have also been shown to be very common in Asian nations, especially in tropical areas.
Clostridium botulinum
The neurotoxin that C. botulinum produces is the source of foodborne botulism, a sickness primarily contracted through eating of processed, unclean seafood. Human foodborne botulism is caused by toxins A, B, E, and F that are produced by the bacteria and are categorized according to immunological criteria (Iwamoto et al., 2010). Notably, at temperatures in refrigeration as low as 3.3°C, C. botulinum type E, the most commonly found form linked to the aquatic environment, could multiply and produce the neurotoxin (Horowitz, 2010).
Staphylococcus aureus
Enterotoxigenic S. aureus is mostly found in humans, and handling of seafood in unsanitary settings could introduce it. Regarding food security, this bacterium’s pathogenicity and virulence are due to the staphylococcal enterotoxins it produces. These enterotoxins can induce gastroenteritis, which is primarily seen in patients as vomiting (Argudin et al., 2010; Fisher et al., 2018).
Aeromonas spp
In Bangladesh and India, there have been a few small outbreaks of Aeromonas spp linked to seafood. Epizootic Ulcerative Syndrome (EUS) in various fish is caused by Aeromonas spp, which seriously compromises the nutritional value of seafood products. According to Aberoum and Jooyandeh (2010), the colonization of the gut by this bacteria in the marine environment may be the cause of the contamination of seafood. Frozen shrimp include the A. hydrophila HG2 and HG3 strains that are thought to be responsible for outbreaks in Finland (Hanninen et al., 1997).
Shigella spp
There are a small number of instances of shigellosis due to the ingestion of seafood items. In their study, Wang et al. (2011) found that 32% of seafood samples (including shrimps, salmon, and tilapia) tested positive for Shigella spp using PCR, but none were successfully isolated using culture methods. S. dysenteriae was found in two types of edible fishes, Megalaspis cordyla and Priacanthus hamrur, in India (Sujatha et al., 2011). Fever, abdominal pain, tenesmus, and bloody diarrhea are all signs of shigellosis. This bacterium can survive in stomach acid by utilizing its multiple virulence factors to attack intestinal cells (Wang et al., 2011).
Escherichia coli
Escherichia coli serogroup 0157 is considered a significant foodborne pathogen in various regions globally (WHO, 1997). E. coli is capable of producing numerous enterotoxins, making it a common culprit for causing foodborne infections (Sharma et al., 2005). Infection with E. coli 0157:H7 can lead to intense bloody diarrhea (Haemorrhagic Colitis, HC), as well as ongoing issues like Haemolytic Uraemic Syndrome (Kumar et al., 2001).
Seafood associated with viruses
Norovirus
Referred to as “RNA calicivirus,” this infection is highly contagious and affects humans. Norovirus is divided into two Geno groups, GI and GII, both of which can lead to human infection (Woods et al., 2016; Bazzardi et al., 2014). This illness, caused by consuming undercooked shellfish and oysters, is identified as the main cause of digestive issues without the presence of bacteria (Woods et al., 2016). Mussels and clams, crab, prawn, and finfish were identified as the primary origins of norovirus (Bazzardi et al., 2014). This infection presents symptoms such as vomiting, feeling nauseous, experiencing abdominal cramps, headache, and fever (Iwamoto et al., 2010).
Hepatitis A Virus
It is a non-enveloped virus that is a part of the Hepatovirus genus and the Picornaviridae family. Hepatitis A virus is naturally found in humans and other vertebrates’ habitats (ICTV, 2012). Signs of this illness may manifest within 2 to 3 weeks (WHO, 2016) or even as long as 45 days (Richards, 2013). Children show no signs; majority of patients experience mild symptoms but these may be intense in elderly or immunocompromised individuals. Signs of this illness include lack of appetite, high body temperature, stomach discomfort, yellowing of the skin, and loose stools (Ghasemian et al., 2016). HAV is a serious illness with a minimal mortality rate. The primary causes of this illness include using water contaminated with faeces, consuming seafood that is contaminated, and poor hygiene practices (Richards, 2013).
Control of Hazards in Seafood
Prevention of pre-harvest contamination
Certain harmful bacteria are commonly found in the water (C. botulinum type E, pathogenic Vibrio sp, Aeromonas sp) and the surroundings (C. botulinum type A, B, Listeria monocytogenes). Therefore, these pathogens could also be present on the live fish or raw fish material. It is either not possible or highly challenging to avoid pre-harvest contamination with disease agents. It is difficult to alter nature, so disease-causing agents like pathogenic bacteria, parasites, and biotoxins will always exist naturally, while prevention of chemical and faecal pollution (such as some pathogenic bacteria and enteric viruses) comes with a price. Monitoring the fishing areas for toxic algae and faecal pollution is crucial as an immediate preventive measure (Oliver, 1988; Richards, 1985). Regrettably, a more precise indicator for the presence of viruses in shellfish or their surrounding waters has not yet been discovered.
Preventive measures during processing
While processing fish products, harmful microorganisms from the raw material might remain in the final product or could be removed. Additionally, there is the potential for further contamination with new pathogens. Potential post-harvest hazards or defects include physical hazards such as foreign material contamination (glass, metal) or presence of bones in boneless cuts. Measures to prevent post-harvest contamination include good manufacturing practices (GMP), sanitation programs, proper factory construction as specified in SSOP, and USA-required “prerequisites” (Federal Register, Vol). European legislation (Directive, 1991), Codex Alimentarius (FAO/WHO, 1997), and 60 No. 242, 1995 part 123 specify the regulations.
Preventive measures in final product
The primary approach adopted by many countries to decrease food safety risks has been to minimize the initial presence of microbes. Many studies have been conducted to establish safe preservative conditions for inhibiting the growth of harmful pathogens, and in most instances, these conditions are widely recognized and can be implemented. Some cases include the development of L. monocytogenes in lightly preserved fish items (e.g., cold smoked salmon). The typical preservative factors (smoke components, 3-5% water phase salt (WPS), storage temperature < 5°C) alone cannot prevent growth, so additional measures (shelf life constraints) must be implemented or devised.
Conclusion
Various types of bacteria such as Vibrio spp, Salmonella spp, L. monocytogenes, S. aureus, C. botulinum, Shigella spp, and Aeromonas spp pose a microbiological threat to seafood. These bacteria are able to infect seafood products at any point in the supply chain, from the farm to the consumer’s table. Reducing bacterial risks is possible by preserving the microbiological water quality of household catch, handling after harvesting, and maintaining good hygiene, adhering to GMP, GHP, and HACCP guidelines. Additional methods to avoid foodborne illnesses from seafood consumption include educating consumers on proper food handling techniques, preparing seafood correctly, and storing it appropriately.
References and sources consulted by the author on the elaboration of this article are available under previous request to our editorial staff.
Vivek Chauhan
Kerala University of Fisheries and Ocean Studies, Kochi, Kerala, 682506
Arya Singh
ICAR – Central Institute of Fisheries Education, Mumbai, 400061
Shyni K
Kerala University of Fisheries and Ocean Studies, Kochi, Kerala, 682506
Shashank Singh
Acharya Narendra Deva University of Agriculture and Technology, Kumarganj, 224229
Email: vivekvijaysingh1@gmail.com
