Water Quality and Food Safety – II

Waterborne Diseases 

Waterborne diseases are major causes of morbidity and mortality worldwide, because a person’s health may be affected by ingestion of contaminated water directly or through food. Nonetheless, person’s health may also be affected by the use of contaminated water for the purposes of personal hygiene and recreation. Thus problem is especially acute where general hygiene and environmental sanitation are poor and where there is inadequate supply of safe water, whereas developing countries carry a heavy burden of the water borne disease, the heaviest being the diarrheal diseases. Thus waterborne diseases are caused by pathogenic microorganisms that most commonly are transmitted in contaminated fresh water, whether in bathing, washing, drinking, or in the preparation of food, where various forms of diarrheal disease probably are the most common episodes occur in all countries, but they are 5 to 6 times more common in developing countries. According to the World Health Organization, it accounts for an estimated 4.1% of the total daily global burden of disease, causing about 1.8 million human deaths annually. The World Health Organization estimates that 88% of that burden is attributable to unsafe water supply, sanitation and hygiene, and is mainly affects children in developing countries.

Microorganisms causing characteristically waterborne diseases include protozoa and bacteria, many of which are intestinal parasites, or invade the tissues or circulatory system through walls of the digestive tract. Various other waterborne diseases are caused by viruses; as a matter of convenience in this connection they might well be regarded as microorganisms. Yet other important classes of water-borne diseases are caused by metazoan parasites. Typical examples include certain Nematoda, that is to say "roundworms", and also certain members of the Schistosomatidae, a family of blood flukes. The latter usually infect victims that make skin contact with the water.

The blood flukes are the pathogens causing Schistosomiasis of various forms, more or less seriously affecting hundreds of millions of people world-wide. As for Nematode infections, one important water-borne nematodal disease is Dracunculiasis. It is acquired by swallowing water in which copepoda occur, that happen to be infected with Nematode larvae in the genus Dracunculus. The larvae cause guinea worm disease.

Even before the establishment of the germ theory of disease, or any advanced understanding of the nature of water as a vehicle for transmitting disease, traditional beliefs cautioned against the consumption of water, rather favouring processed beverages such as beer, wine and tea. In the camel caravans that crossed Central Asia along the Silk Road, the explorer Owen Lattimore noted, "The reason we drank so much tea was because of the bad water. Water alone, unboiled, is never drunk. There is a superstition that it causes blisters on the feet."

The following tables give you some idea about various possible water borne diseases which happening across the globe. But when it comes to food safety, some of these diseases are having a minimal effect while some of them are having the critical effects. Thus we are going to discuss most of the food related water borne diseases and their prevention strategies as well as treatment methods in the later part of this series. 

   

Waterborne diseases are caused by pathogenic microorganisms, where they can be divided into several groups based on size and the types. 

PROTOZOAL INFECTIONS

Although all protozoal infectious agents in humans are parasites, by convention, parasitic diseases are defined as those caused by protozoa or helminthes. The old classification, in which a single phylum of protozoa encompassed all unicellular eukaryotic microorganisms, is no longer valid because of new ultra-structural and molecular taxonomic information. But here we consider the organisms classified under Amoebozoa, Excavata and Chromalveoata all together other than helminthes to simplify the classification since we are only considering the food safety aspects.

Disease and Transmission	Microbial Agent	Sources of Agent in Water Supply	General Symptoms
Amoebiasis (hand-to-mouth)	Protozoan (Entamoeba histolytica) (Cyst-like appearance)	Sewage, non-treated drinking water, flies in water supply	Abdominal discomfort, fatigue, weight loss, diarrhea, bloating, fever
Cryptosporidiosis (oral)	Protozoan (Cryptosporidium parvum)	Collects on water filters and membranes that cannot be disinfected, animal manure, seasonal runoff of water.	Flu-like symptoms, watery diarrhea, loss of appetite, substantial loss of weight, bloating, increased gas, nausea
Cyclosporiasis	Protozoan parasite (Cyclospora cayetanensis)	Sewage, non-treated drinking water	cramps, nausea, vomiting, muscle aches, fever, and fatigue
Giardiasis (fecal-oral) (hand-to-mouth)	Protozoan (Giardia lamblia) Most common intestinal parasite	Untreated water, poor disinfection, pipe breaks, leaks, groundwater contamination, campgrounds where humans and wildlife use same source of water. Beavers and muskrats create ponds that act as reservoirs for Giardia.	Diarrhea, abdominal discomfort, bloating, and flatulence
Microsporidiosis	Protozoan phylum (Microsporidia), but closely related to fungi	The genera of Encephalitozoon intestinalis has been detected in groundwater, the origin of drinking water	Diarrhea and wasting in immune-compromised individuals.

PARASITIC INFECTIONS

A parasite is an organism that lives on or in a host and gets its food from or at the expense of its host. Parasites can cause disease in humans. Some parasitic diseases are easily treated and some are not. The burden of these diseases often rests on communities in the tropics and subtropics, but parasitic infections also affect people in developed countries. There are three major groups, but we already discussed the first type the Protozoa.

Thus Helminths are multi-celled organisms that can live in or outside of your body. They’re more commonly known as worms. They include flatworms, tapeworms, thorny-headed worms, and roundworms.

Ectoparasites are multi-celled organisms that live on or feed off your skin. They include some insects and arachnids, such as mosquitos, fleas, ticks, and mites.

However, we only consider the organisms which are distributed by water and its food safety concerns.

Disease and Transmission	Microbial Agent	Sources of Agent in Water Supply	General Symptoms
Schistosomiasis (immersion)	Members of the genusSchistosoma	Fresh water contaminated with certain types of snails that carry schistosomes	Rash or itchy skin. Fever, chills, cough and muscle aches
Dracunculiasis (Guinea Worm Disease)	Dracunculus medinensis	Stagnant water containing larvae, generally in parasitised Copepoda	Allergic reaction, urticaria rash, nausea, vomiting, diarrhea, asthmatic attack.
Taeniasis	Tapeworms of the genus Taenia	Drinking water contaminated with eggs	Intestinal disturbances, neurologic manifestations, loss of weight, cysticercosis
Fasciolopsiasis	Fasciolopsis buski	Drinking water contaminated with encysted metacercaria	GIT disturbance, diarrhea, liver enlargement, cholangitis, cholecystitis, obstructive jaundice.
Hymenolepiasis (Dwarf Tapeworm Infection)	Hymenolepis nana	Drinking water contaminated with eggs	Abdominal pain, severe weight loss, itching around the anus, nervous manifestation
Echinococcosis (Hydatid disease)	Echinococcus granulosus	Drinking water contaminated with feces (usually canid) containing eggs	Liver enlargement, hydatid cysts press on bile duct and blood vessels; if cysts rupture they can cause anaphylactic shock
coenurosis	multiceps multiceps	contaminated drinking water with eggs	increases intacranial tension
Ascariasis	Ascaris lumbricoides	Drinking water contaminated with feces (usually canid) containing eggs	Mostly, disease is asymptomatic or accompanied by inflammation, fever, and diarrhea. Severe cases involve Löffler's syndrome in lungs, nausea, vomiting, malnutrition, and underdevelopment.
Enterobiasis	Enterobius vermicularis	Drinking water contaminated with eggs	Peri-anal itch, nervous irritability, hyperactivity and insomnia

VIRAL INFECTIONS

A virus is a small infectious organism—much smaller than a fungus or bacterium—that must invade a living cell to reproduce (replicate). The virus attaches to a cell (called the host cell), enters it, and releases its DNA or RNA inside the cell. The virus’s DNA or RNA is the genetic material containing the information needed to make copies of (replicate) the virus. The virus’s genetic material takes control of the cell and forces it to replicate the virus. The infected cell usually dies because the virus keeps it from performing its normal functions. When it dies, the cell releases new viruses, which go on to infect other cells. Viruses are classified as DNA viruses or RNA viruses, depending on whether they use DNA or RNA to replicate. 

Viruses usually infect one particular type of cell. For example, common cold viruses infect only cells of the upper respiratory tract. Viruses are spread (transmitted) in various ways. Some are swallowed, some are inhaled, and some are spread by the bites of insects, such as mosquitoes, certain biting flies, or ticks. Some are spread sexually or during transfusion of contaminated blood.

When a cell is infected with a virus several effects may be seen. Many viruses cause no harm or disease whatsoever. However, some viruses may attack certain cells and multiply within them. Once mature the daughter viruses break the cell and spread elsewhere. This is called a lytic infection. Eventually, if host immunity operates effectively, the virus-infected cell may be killed by the host, leading to interruption of the virus cycle and cure of the infection. However, this is not true for all viral infections. The viruses may persist in the cell without damaging it and make the cell a carrier. The patient may appear to be cured but the infection persists and can spread to others. In addition, the infection may reappear later after this period of lull or latency.

Disease and Transmission	Microbial Agent	Sources of Agent in Water Supply	General Symptoms
Adenovirus infection	Adenovirus	Manifests itself in improperly treated water	Symptoms include common cold symptoms, pneumonia, croup, and bronchitis
Gastroenteritis	Astrovirus, Calicivirus, Enteric Adenovirus, and Parvovirus	Manifests itself in improperly treated water	Symptoms include diarrhea, nausea, vomiting, fever, malaise, and abdominal pain
SARS (Severe Acute Respiratory Syndrome)	Coronavirus	Manifests itself in improperly treated water	Symptoms include fever, myalgia, lethargy, gastrointestinal symptoms, cough, and sore throat
Hepatitis A	Hepatitis A virus (HAV)	Can manifest itself in water (and food)	Symptoms are only acute (no chronic stage to the virus) and include Fatigue, fever, abdominal pain, nausea, diarrhea, weight loss, itching, jaundice and depression.
Poliomyelitis (Polio)	Poliovirus	Enters water through the feces of infected individuals	90-95% of patients show no symptoms, 4-8% have minor symptoms (comparatively) with delirium, headache, fever, and occasional seizures, and spastic paralysis, 1% have symptoms of non-paralytic aseptic meningitis. The rest have serious symptoms resulting in paralysis or death
Polyomavirus infection	Two of Polyomavirus: JC virus and BK virus	Very widespread, can manifest itself in water, ~80% of the population has antibodies to Polyomavirus	BK virus produces a mild respiratory infection and can infect the kidneys of immunosuppressed transplant patients. JC virus infects the respiratory system, kidneys or can cause progressive multifocal leukoencephalopathy in the brain (which is fatal).

BACTERIAL INFECTIONS

Bacteria are living things that have only one cell. Under a microscope, they look like balls, rods, or spirals. They are so small that a line of 1,000 could fit across a pencil eraser. Most bacteria won't hurt you - less than 1 percent of the different types make people sick. Many are helpful. Some bacteria help to digest food, destroy disease-causing cells, and give the body needed vitamins. Bacteria are also used in processing various foods such as yogurt and cheese.  

Bacterial infections are illnesses that occur when harmful forms of bacteria multiply inside the body. Harmful bacteria that cause bacterial infections and disease are called pathogenic bacteria. Bacterial diseases occur when pathogenic bacteria get into the body and begin to reproduce and crowd out healthy bacteria, or to grow in tissues that are normally sterile. Harmful bacteria may also emit toxins that damage the body. They range from mild to severe; although they include such deadly diseases such as plague, tuberculosis, and cholera.  However, most of the bacterial infections can be prevented by good sanitation or cured by antibiotics.

Bacteria are everywhere: in soil, in water, in air, and in the bodies of every person and animal. These microorganisms are among the most numerous forms of life on Earth. Most bacteria are either harmless, or helpful, or even essential to life. Bacteria break down (decompose) dead plants and animals. This allows chemical elements like carbon to return to the earth to be used again. In addition, some bacteria help plants get nitrogen. Without them, plants could not grow. In the human body, bacteria help keep the digestive tract working properly.

Disease and Transmission	Microbial Agent	Source of Agent in Water Supply	General Symptoms
Botulism	Clostridium botulinum	Bacteria can enter an open wound from contaminated water sources. Can enter the gastrointestinal tract by consuming contaminated drinking water or (more commonly) food	Dry mouth, blurred and/or double vision, difficulty swallowing, muscle weakness, difficulty breathing, slurred speech, vomiting and sometimes diarrhea. Death is usually caused by respiratory failure.
Campylobacteriosis	Most commonly caused by Campylobacter jejuni	Drinking water contaminated with feces	Produces dysentery like symptoms along with a high fever. Usually lasts 2–10 days.
Cholera	Spread by the bacterium Vibrio cholerae	Drinking water contaminated with the bacterium	In severe forms it is known to be one of the most rapidly fatal illnesses known. Symptoms include very watery diarrhea, nausea, cramps, nosebleed, rapid pulse, vomiting, and hypovolemic shock (in severe cases), at which point death can occur in 12–18 hours.
E. coli	Certain strains of Escherichia coli (commonly E. coli)	Water contaminated with the bacteria	Mostly diarrhea. Can cause death in immunocompromised individuals, the very young, and the elderly due to dehydration from prolonged illness.
M. marinum	Mycobacterium marinum	Naturally occurs in water, most cases from exposure in swimming pools or more frequently aquariums; rare infection since it mostly infects immunocompromised individuals	Symptoms include lesions typically located on the elbows, knees, and feet (from swimming pools) or lesions on the hands (aquariums). Lesions may be painless or painful.
Dysentery	Caused by a number of species in the genera Shigella and Sallmonella with the most common being Shigella dysenteriae	Water contaminated with the bacterium	Frequent passage of feces with blood and/or mucus and in some cases vomiting of blood.
Legionellosis (two distinct forms: Legionnaires’ disease and Pontiac fever)	Caused by bacteria belonging to genus Legionella (90% of cases caused by Legionella pneumophila)	Contaminated water: the organism thrives in warm aquatic environments.	Pontiac fever produces milder symptoms resembling acute influenza without pneumonia. Legionnaires’ disease has severe symptoms such as fever, chills, pneumonia (with cough that sometimes produces sputum), ataxia, anorexia, muscle aches, malaise and occasionally diarrhea and vomiting
Leptospirosis	Caused by bacterium of genus Leptospira	Water contaminated by the animal urine carrying the bacteria	Begins with flu-like symptoms then resolves. The second phase then occurs involving meningitis, liver damage (causes jaundice), and renal failure
Otitis Externa (swimmer’s ear)	Caused by a number of bacterial and fungal species.	Swimming in water contaminated by the responsible pathogens	Ear canal swells causing pain and tenderness to the touch
Salmonellosis	Caused by many bacteria of genus Salmonella	Drinking water contaminated with the bacteria. More common as a food borne illness.	Symptoms include diarrhea, fever, vomiting, and abdominal cramps
Typhoid fever	Salmonella typhi	Ingestion of water contaminated with feces of an infected person	Characterized by sustained fever up to 40°C (104°F), profuse sweating, diarrhea, less commonly a rash may occur. Symptoms progress to delirium and the spleen and liver enlarge if untreated. In this case it can last up to four weeks and cause death.
Vibrio Illness	Vibrio vulnificus, Vibrio alginolyticus, and Vibrio parahaemolyticus	Can enter wounds from contaminated water. Also got by drinking contaminated water or eating undercooked oysters.	Symptoms include explosive, watery diarrhea, nausea, vomiting, abdominal cramps, and occasionally fever.