Foodborne Viruses- Food Poisoning by Viruses

Foodborne viruses are microscopic agents that can cause infections and diseases in humans through the consumption of contaminated food or water. Unlike bacteria, viruses cannot grow or multiply in food, but they can survive for long periods of time under various environmental conditions. Foodborne viruses can cause a range of symptoms, such as nausea, vomiting, diarrhea, fever, abdominal pain, jaundice, and liver damage. Some foodborne viruses can also have serious long-term consequences, such as chronic hepatitis, neurological disorders, and cancer.

The main source of foodborne viruses is the fecal-oral route, which means that the viruses are shed in the feces or other body fluids of infected humans or animals and then transferred to food or water through direct or indirect contact. For example, foodborne viruses can contaminate food through:

• Infected food handlers who do not practice good hygiene and sanitation during food preparation and handling.
• Raw or undercooked animal products (such as meat, poultry, seafood, eggs, and dairy) that harbor zoonotic viruses (viruses that can infect both animals and humans).
• Fresh produce (such as fruits, vegetables, and herbs) that are grown on land fertilized with animal waste or irrigated with contaminated water.
• Shellfish (such as oysters, mussels, and clams) that are harvested from waters polluted by human sewage or animal runoff.
• Drinking water or ice that is not adequately treated or filtered to remove viral particles.

Other sources of foodborne viruses include:

• Droplets from an infected person who coughs or sneezes near food or utensils.
• Sexual intercourse with an infected person who has a sexually transmitted viral infection (such as hepatitis B or C).
• Contaminated blood or blood products that are transfused or injected into a person.
• Vectors (such as mosquitoes and ticks) that carry arthropod-borne viruses (viruses that are transmitted by insects).

The most common foodborne viruses include human noroviruses, hepatitis A virus, rotavirus, hepatitis E virus, and astrovirus. Other foodborne viruses include sapovirus, adenovirus, enterovirus, coronavirus, parvovirus, calicivirus, reovirus, and picornavirus. These viruses vary in their characteristics, transmission routes, host range, incubation period, symptoms, severity, treatment, and prevention.

To reduce the risk of foodborne viral infections, it is important to follow the four basic steps of food safety: clean, separate, cook, and chill. Additionally, it is advisable to:

• Wash hands thoroughly with soap and water before and after handling food and after using the toilet or changing diapers.
• Avoid preparing food for others if you are sick with diarrhea or vomiting.
• Cook animal products to the recommended internal temperatures to kill any potential viruses.
• Rinse fresh produce under running water and peel or discard outer layers if possible.
• Avoid eating raw or undercooked shellfish or seafood from unknown sources.
• Drink only treated or boiled water and avoid ice made from untreated water.
• Get vaccinated against hepatitis A and B if you are traveling to areas where these infections are endemic or if you belong to a high-risk group.
• Use condoms during sexual intercourse to prevent sexually transmitted viral infections.

Foodborne viruses are a major public health concern worldwide and can cause significant morbidity and mortality. By understanding their sources of contamination and taking preventive measures, we can protect ourselves and our loved ones from these harmful pathogens.

Foodborne viruses are viruses that can cause illness in humans through the consumption of contaminated food or water. Some of the most common foodborne viruses are:

• Human noroviruses: These are small, single-stranded RNA viruses that belong to the Caliciviridae family. They have six genogroups (GI to GVI), of which GI, GII, and GIV can infect humans and cause gastroenteritis. They are the most common cause of foodborne illness, responsible for 58% of foodborne illnesses in the United States. They can cause symptoms such as vomiting, diarrhea, and stomach cramps within 24 to 48 hours of exposure. They are highly contagious and can spread through fecal-oral route, person-to-person contact, or contact with contaminated surfaces. They can survive in low pH and high temperatures and remain infectious in food and water for a long time. There is no specific treatment or vaccine for norovirus infection, so prevention measures such as good hygiene and sanitation are important.
• Hepatitis A virus: This is a single-stranded RNA virus that belongs to the Picornaviridae family. It has only one serotype but seven genotypes (I to VII), of which I, II, and III can infect humans and cause hepatitis A. Hepatitis A is a liver infection that can cause symptoms such as jaundice, dark urine, vomiting, fever, and loss of appetite. The incubation period of hepatitis A virus is about 28 days, and the symptoms can last from a few weeks to several months. Hepatitis A virus can also spread through fecal-oral route, especially from consumption of raw or undercooked shellfish, fruits, vegetables, or water contaminated with human feces. Hepatitis A virus can resist low pH and high temperatures and survive in food and water for a long time. There is a vaccine for hepatitis A virus that can provide lifelong immunity, but there is no specific treatment for hepatitis A infection.
• Rotavirus: This is a double-stranded RNA virus that belongs to the Reoviridae family. It has eight groups (A to H), of which A to C can infect humans and cause rotavirus gastroenteritis. Rotavirus gastroenteritis is a severe diarrheal disease that mainly affects infants and young children under 5 years of age. It can cause symptoms such as dehydration, flatulence, nausea, vomiting, fever, and abdominal pain within 1 to 3 days of exposure. Rotavirus can also spread through fecal-oral route or contact with contaminated surfaces. Rotavirus can survive in low pH and moderate temperatures and remain infectious in food and water for a long time. There are two vaccines for rotavirus that can prevent severe rotavirus gastroenteritis, but there is no specific treatment for rotavirus infection.

Other foodborne viruses that can cause illness in humans include:

• Hepatitis E virus: This is a single-stranded RNA virus that belongs to the Hepeviridae family. It has eight genotypes (1 to 8), of which 1 to 4 can infect humans and cause hepatitis E. Hepatitis E is similar to hepatitis A in terms of symptoms and transmission routes, but it has a longer incubation period (2 to 10 weeks) and can cause more severe complications such as fulminant hepatitis or chronic hepatitis in immunocompromised individuals or pregnant women. There is no vaccine or specific treatment for hepatitis E virus infection.
• Sapovirus: This is a single-stranded RNA virus that belongs to the Caliciviridae family. It has five genogroups (GI to GV), of which GI to GIV can infect humans and cause sapovirus gastroenteritis. Sapovirus gastroenteritis is similar to norovirus gastroenteritis in terms of symptoms and transmission routes, but it has a shorter incubation period (12 to 48 hours) and a lower prevalence rate. There is no specific treatment or vaccine for sapovirus infection.
• Astrovirus: This is a single-stranded RNA virus that belongs to the Astroviridae family. It has eight serotypes (HAstV-1 to HAstV-8), all of which can infect humans and cause astrovirus gastroenteritis. Astrovirus gastroenteritis is similar to rotavirus gastroenteritis in terms of symptoms and transmission routes, but it has a milder severity and a lower prevalence rate. There is no specific treatment or vaccine for astrovirus infection.

Besides human noroviruses and hepatitis A virus, there are other viruses that can cause foodborne infections in humans. Two of them are rotavirus and hepatitis E virus.

• Rotavirus: Rotavirus causes infantile diarrhea in children under 5 years of age, mostly in developing countries where sanitation and hygiene are poor. It is estimated that rotavirus causes about 215,000 deaths per year among children. Rotavirus is transmitted by the fecal-oral route, through contact with contaminated food, water, surfaces or hands. Symptoms include fever, abdominal pain, watery diarrhea and vomiting, which can lead to dehydration and malnutrition. Rotavirus infection usually lasts for a week and immunity develops after exposure. Vaccination is recommended by the World Health Organization (WHO) to prevent severe rotavirus disease.
• Hepatitis E virus: Hepatitis E virus (HEV) is a small single-stranded RNA virus that causes acute hepatitis in humans. HEV has four genotypes, of which genotypes 1 and 2 are restricted to humans and genotypes 3 and 4 are zoonotic, meaning they can infect both animals and humans. HEV is endemic in many parts of the world, especially Asia and Africa, where it is associated with outbreaks linked to contaminated water or food. HEV can also be transmitted by consumption of undercooked pork, deer or shellfish products that contain the virus. The incubation period of HEV ranges from 2 to 10 weeks, and symptoms include fever, malaise, anorexia, nausea, abdominal pain, dark urine and jaundice. Most cases of HEV infection are self-limiting and resolve within 4 to 6 weeks, but some may progress to fulminant hepatitis, especially in pregnant women or immunocompromised individuals. There is no specific treatment for HEV infection, but a vaccine has been developed and licensed in China.

These are some examples of other viruses that can cause foodborne infections in humans. However, there are also emerging viruses that have been detected in food or animals and may pose a potential threat to human health. These include severe acute respiratory syndrome (SARS) virus, Nipah virus (NiV), H5N1 virus, coronavirus disease 2019 (COVID-19) virus and others. Therefore, it is important to monitor the occurrence and diversity of foodborne viruses using molecular methods and adopt a One Health approach that considers the interconnection between human, animal and environmental health.

Foodborne viruses are responsible for a large proportion of foodborne illnesses worldwide. According to the Centers for Disease Control and Prevention (CDC), about 31 viral pathogens cause 9.4 million foodborne illnesses in the United States each year. Among them, human norovirus (hNoV) is the most common, accounting for 58% of foodborne illnesses and 11% of foodborne deaths. Other important foodborne viruses include hepatitis A virus (HAV), hepatitis E virus (HEV), rotavirus, and sapovirus.

The epidemiology of foodborne viruses depends on various factors, such as the source and route of contamination, the environmental stability and resistance of the virus, the host susceptibility and immunity, and the availability of prevention and control measures. Some of the key aspects of foodborne viral epidemiology are:

• Foodborne viruses are mainly transmitted through the fecal-oral route, either by direct contact with infected persons or animals, or by ingestion of contaminated food or water. The main sources of contamination are fecally polluted irrigation water, raw or undercooked animal products, shellfish harvested from contaminated waters, and ready-to-eat foods handled by infected food workers.
• Foodborne viruses can survive in a wide range of pH, temperature, and salinity conditions, and can persist on food and environmental surfaces for long periods. They can also withstand some food processing methods, such as freezing, drying, and pasteurization. Therefore, they pose a significant challenge for food safety and quality assurance.
• Foodborne viruses have a low infectious dose, meaning that only a few viral particles can cause illness in humans. The incubation period varies depending on the type of virus, but it is usually between 12 and 48 hours for hNoV and HAV, and between 15 and 60 days for HEV. The symptoms of foodborne viral infections are typically acute and self-limiting, characterized by gastroenteritis, nausea, vomiting, diarrhea, fever, and abdominal pain. However, some infections can lead to severe complications or chronic sequelae, such as liver failure, neurological disorders, or cancer.
• Foodborne viruses affect people of all ages and backgrounds, but some groups are more vulnerable or at risk than others. These include infants, young children, elderly people, pregnant women, immunocompromised individuals, travelers, and people living in areas with poor sanitation and hygiene. The burden of foodborne viral diseases is higher in developing countries than in developed countries due to the lack of safe water supply, adequate sanitation facilities, effective surveillance systems, and public health interventions.
• Foodborne viruses can be prevented and controlled by implementing a combination of measures at different levels of the food chain. These include improving agricultural practices, ensuring good hygiene and sanitation during food production, processing, distribution, and preparation, applying hazard analysis and critical control point (HACCP) principles to identify and eliminate potential sources of contamination, educating consumers and food handlers about safe food handling practices and personal hygiene habits, providing access to safe drinking water and sanitation services, enhancing surveillance and outbreak investigation capacities, developing rapid and reliable diagnostic methods for virus detection and characterization, promoting vaccination against HAV and rotavirus where available and indicated, and enforcing appropriate regulations and standards for food safety.

Foodborne viruses can cause a variety of symptoms depending on the type and dose of the virus, the host factors, and the route of transmission. The most common symptoms of foodborne viral infections are vomiting, diarrhea (with or without blood), fever, abdominal cramping, headache, dehydration, myalgia, and arthralgias. These symptoms usually appear within 12 to 48 hours after ingestion of contaminated food or water and last for one to seven days. However, some viruses may have longer incubation periods (up to 50 days for hepatitis A virus) or cause more severe or chronic complications (such as liver failure for hepatitis E virus or Guillain-Barré syndrome for Campylobacter-associated enterovirus).

The clinical manifestation of foodborne viral infections is often nonspecific and similar to other causes of gastroenteritis, such as bacteria or parasites. Therefore, definitive diagnosis can be made only through stool culture or more advanced laboratory testing, such as polymerase chain reaction (PCR), enzyme-linked immunosorbent assay (ELISA), or immunoelectron microscopy. However, these tests are not widely available or routinely performed in clinical settings, especially in resource-limited settings. As a result, many cases of foodborne viral infections are underreported or misdiagnosed.

The treatment of foodborne viral infections is mainly supportive and symptomatic, as there are no specific antiviral drugs or vaccines for most of these viruses. The main goals of treatment are to prevent dehydration and electrolyte imbalance, to control nausea and vomiting, and to relieve pain and fever. Oral rehydration therapy (ORT) is the preferred method of rehydration for mild to moderate dehydration, while intravenous fluids may be required for severe dehydration or shock. Antiemetics, antidiarrheals, analgesics, and antipyretics may be used as adjunctive therapy if indicated. However, some of these medications may have adverse effects or contraindications in certain situations, such as pregnancy, liver disease, or immunosuppression. Therefore, consultation with a healthcare provider is recommended before using any medication for foodborne viral infections.

Some foodborne viruses may require specific treatment or prophylaxis in addition to supportive care. For example, hepatitis A virus infection can be prevented by post-exposure prophylaxis with immunoglobulin or vaccine within two weeks of exposure. Hepatitis E virus infection may require antiviral therapy with ribavirin or interferon in pregnant women or patients with chronic liver disease. Rotavirus infection can be prevented by vaccination in infants and young children. Norovirus infection can be controlled by strict infection prevention and control measures in healthcare facilities and community settings.

Foodborne viral infections are common and often self-limiting, but they can also cause significant morbidity and mortality in vulnerable populations. Early recognition and appropriate management of foodborne viral infections can reduce the risk of complications and transmission. Prevention of foodborne viral infections relies on good hygienic practices by food handlers and consumers, safe water supply and sanitation, proper cooking and storage of food, and vaccination when available.

Foodborne viruses are difficult to detect because they are very small, cannot be cultured in the laboratory, and have a low infectious dose. Therefore, traditional methods such as electron microscopy and cultural isolation are not suitable for routine detection of foodborne viruses. Instead, more advanced methods based on immunological, molecular, and biosensor technologies have been developed and applied for foodborne virus detection.

Immunological methods use antibodies that recognize specific antigens on the surface of viruses. These methods include enzyme-linked immunosorbent assay (ELISA), immunochromatographic assay (ICA), and immunomagnetic separation (IMS). Immunological methods are simple, rapid, and sensitive, but they have some limitations such as cross-reactivity, low specificity, and interference from food matrices.

Molecular methods use nucleic acid amplification techniques to detect viral genomes or transcripts in food samples. These methods include polymerase chain reaction (PCR), reverse transcription PCR (RT-PCR), real-time PCR (qPCR), multiplex PCR, nucleic acid sequence-based amplification (NASBA), loop-mediated isothermal amplification (LAMP), and DNA microarray. Molecular methods are highly sensitive, specific, and versatile, but they require expensive equipment, skilled personnel, and rigorous quality control. Moreover, molecular methods cannot distinguish between viable and non-viable viruses.

Biosensor methods use biological recognition elements such as antibodies, aptamers, or phages to capture and signal the presence of viruses in food samples. These methods include surface plasmon resonance (SPR), electrochemical biosensors, optical biosensors, and phage-based biosensors. Biosensor methods are fast, portable, and user-friendly, but they need further optimization and validation for foodborne virus detection.

Recently, a novel detection method based on CRISPR/Cas technology has emerged as a promising tool for foodborne virus detection. CRISPR/Cas is a bacterial adaptive immune system that can target and cleave specific DNA or RNA sequences using guide RNAs and Cas proteins. This method can be combined with different signal amplification and detection strategies such as fluorescence, colorimetry, or SERS to achieve high sensitivity and specificity for foodborne virus detection.

The following table summarizes the main advantages and disadvantages of the current detection methods for foodborne viruses:

These detection methods play a crucial role in ensuring food safety and preventing foodborne viral infections.

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