Giardiasis (giardia) in adults - signs, symptoms and treatment

Giardia is a protozoan, nasty and common parasite that is very easy to become infected with.

As soon as Giardia penetrates the human body, it quickly masters it. However, microorganisms do not disdain cats and dogs. Often, it is from their pets that owners receive these guests.

Giardiasis can be asymptomatic for a long time, and therefore is not perceived as a dangerous pathology. Here lies a risk to human health.

What is giardiasis?

Giardiasis is an invasive disease caused by protozoan parasites and characterized by damage to the small intestine. The main manifestations of giardiasis are allergic and pathological neurological reactions.

The causative agent of giardiasis is the simplest flagellated microorganism – lamblia (Giardia). Modern science knows about 40 varieties of Giardia, but only Lamblia interstinalis parasitizes the human intestine.

This protozoan microorganism exists in the form of a cyst and in the form of vegetation. Vegetative lamblia has a pear-shaped shape, somewhat reminiscent of a human face with a tight smile. Giardia does not reach more than 24 microns in length and 12 microns in width, so they are visible only under a microscope.

On the ventral side of the parasite there is a suction disk, which is used to attach to the villi lining the human intestine. Giardia feeds on the entire surface of the body, absorbing the substances they need for life.

In the form of vegetation, Giardia moves very actively. Flagella help them in this; the parasite has 4 pairs of them. Outside the human body, vegetative forms are not capable of long-term existence and die within a few hours.

After the parasites penetrate the human intestine, Giardia begins to divide, forming a new vegetation and cyst. Cysts are released along with the patient’s stool. Unlike vegetations, cysts have good stability in the environment. They retain their viability without a human body for 18 days or more in water, and with sufficient humidity they live for about 4 days. Cysts do not respond to treatment with chlorine, but do not tolerate drought. Without sufficient moisture, the cysts die within a few hours.

Giardia leads an independent lifestyle, completely providing for its needs at the expense of the host’s body. Giardiasis is widespread. Most carriers of this protozoal infection live in Latin America, Africa and Central Asia. The causative agent of the disease was first discovered in human feces in 1684 by Antonia van Leeuwenhoek, and the scientist D. F. Lambl described the parasite in detail in 1859. This microorganism was named after him.

Animals, along with humans, are susceptible to giardiasis. This parasitic infestation is found in rabbits, dogs, cats, rodents, cattle and other mammals. A person most often becomes infected from another person who releases Giardia cysts into the external environment, but the possibility of infection from animals cannot be ruled out.

Already 9-22 days after the initial invasion, a person becomes dangerous to others, as he begins to release parasite cysts into the external environment with feces, ready for infection. Just 1 g of feces can contain 23 million parasitic cysts, but the average number of cysts per 1 g of feces is 1.8 million. Moreover, for infection to occur, from 1 to 10 cysts can enter the human gastrointestinal tract. Under such conditions, the risk of invasion will range from 10-30%.

Definition of disease

Giardiasis is an intestinal infection caused by the parasite Giardia duodenalis (or Giardia intestinalis, Giardia lamblia - all these are different names for the same protozoan microorganism), which spreads through contact with infected people, contaminated food and water.
The infection is more common in children than in adults. The second name for giardiasis is giardiasis. It is more common in Europe. This happened due to the fact that in Russia the discoverer of the microorganism was D.F. Giardia, who described Giardia in 1859, and in Europe - the French researcher A. Giard.

Giardiasis statistics

Every year more than 140 thousand cases of giardiasis are registered in Russia. The number of adults from this figure is about 30%. The disease is dangerous primarily because it is asymptomatic, and the clinical signs that occur in an adult are not specific. Giardiasis is often hidden under the guise of biliary dyskinesia, chronic enteritis and other pathologies of the gastrointestinal tract.

The mechanism of transmission of parasitic infection is fecal-oral. Routes of transmission: through hands, through water, through food contaminated with parasite cysts. Some insects, in particular flies, can carry Giardia cysts.

The prevalence of giardiasis is explained by the high prevalence of parasite cysts in most environmental objects:

There are from 4 to 30 cysts per 1 cubic meter of water in open reservoirs.
For 1 liter of untreated wastewater, there are up to 1091 cysts.
For 1 liter of treated wastewater that will be discharged into open water bodies, there are from 10 to 35 cysts.
There are up to 112 cysts per 1 kg of soil in preschool educational institutions located in unsewered settlements (in 11-22% of all studied soils).
In 6% of cases, cysts were found in washings from door handles in kindergartens, in 3% in washings from children’s hands, in 2% in washings from children’s potties and in 0.2% in washings from toys.

Cysts remain viable in water from 15 to 70 days; in feces they live from 2 hours to a day. If cysts end up in open waters, they can live for about 3 months at temperatures from 2 to 22 °C. In the sea, cysts retain the ability to invade for 47 days.

However, cysts are not resistant to heat and when boiled they die instantly. As for food products, parasite cysts can remain viable on fruits for 6 hours; in dairy products they can live up to 12 days, and sometimes up to 112 days.

Outbreaks of giardiasis have been reported in various countries around the world due to drinking untreated water that has not been properly treated at water works. For example, a similar situation was observed in America, Egypt, and Sweden.

In most preschool institutions, children become infected through dirty hands. The source of the spread of giardiasis is other children, as well as staff.

The possibility of infection with parasites through food should not be ruled out. Cysts can get onto prepared food products from the hands of those people who have been in contact with them. Or infection occurs by eating poorly processed fruits, vegetables, herbs, etc.

Infection with parasites through products and hands

More than 20% of those infected were infected through handshakes. The main source of infection is food. The cyst enters with contaminated water during irrigation, through the hands of an infected person after cleaning, cooking, excluding heat treatment.

More than half of the cases of infection occur due to dirty hands on which single-celled organisms live.

Minimize hand contamination by preparing food before consumption:

Hands are washed before and after contact with vegetable and fruit products. Do not forget that the towel is not shared. It is important to use disposable paper towels as a rational and safe means of preventing possible infections.
It is advisable to treat products with thick skins with boiling water. The method does not kill parasites completely, but will reduce their number to half and help eliminate them from the body.
Drying food with a napkin or cloth towel after washing is not recommended. A disposable paper towel is safer.
It is more dangerous to become infected with food if you buy it not in special stores, but on the shelves.

Causes of giardiasis infection

The causes of giardiasis infection are infestations by an intestinal parasite called Lamblia intestinalis.

Giardia multiplies in the human small intestine, in those places where they accumulate the most. The method of reproduction is continuous pair division of vegetative individuals. The speed of this process is very high and averages 20 minutes; as a result, the intestines are populated with parasites quite quickly.

The activity of Giardia and the rate of their reproduction directly depends on the state of the human digestive system. The number of individuals decreases sharply during fasting and when the patient eats a sufficient amount of protein food. When carbohydrate foods enter the body, on the contrary, there is insufficient secretion of bile into the intestinal lumen, which stimulates the growth and reproduction of parasites.

The more active the processes of parietal digestion in the intestine, the faster Giardia begins to divide, which explains the high prevalence of infection among children compared to the adult population. Favorable conditions for the existence of the parasite in the intestines are low acidity of gastric juice.

The source of infection is always a sick person. Moreover, he himself may be a carrier of Giardia, but will not experience symptoms of the disease at all. A person becomes contagious approximately 8-12 days after infection. The incubation period in some cases may be shorter, especially with massive Giardia infection.

Cysts are released into the external environment in waves. The pause between this process can range from 1 to 17 days. If a person was infected once, and subsequent reinfection does not occur, then he will remain infectious for 6 months.

From the point of view of maximum contagiousness, the most dangerous is the patient whose symptoms of giardiasis have subsided. During this period, intestinal motility is normalized, and favorable conditions are created for the proliferation of parasites.

One gram of feces can contain about 1.8 million cysts capable of invasion. And in order for infection to occur, it is enough to swallow only 10 cysts.

The mechanism of transmission of Giardia is fecal-oral. Ways of spread of infection: food, household contact and water.

Most often, massive outbreaks of infection result from the waterborne spread of giardiasis. Infection is possible while visiting the pool or when swimming in open water. Giardiasis can be transmitted by eating food contaminated with cysts of the parasite. There are known cases of infection during sexual contact between homosexual men.

There is a high risk of transmission of giardiasis under the following conditions:

Lack of personal hygiene. First of all, this concerns poor quality and untimely washing of hands after visiting public places, the toilet and before eating.
Poor quality processing of food products that are eaten raw.
Drinking unboiled water, especially from open natural sources. Giardia can be present in any water, including spring water.
Poor sanitary living conditions, presence of insects in the house. Of particular danger in this regard are flies and cockroaches, which spread the infection.
It is possible to become infected with giardiasis from infested animals: dogs, guinea pigs, cats, etc.

Adults in the following professions are more susceptible to infection:

Employees of educational institutions (kindergartens, schools).
Medical workers (laboratory technicians).
Vacuum trucks.

Risk factors for the development of giardiasis in adults:

A large amount of carbohydrate foods in the diet.
Insufficient consumption of protein foods and foods with plant fiber (vegetables, fruits, cereals).
Reduced stomach acidity.
Impaired immune function.
Long-term treatment with antibacterial drugs, which leads to bacterial overgrowth in the intestines. Such an environment is favorable for the existence of Giardia.
Addiction.

In the Russian Federation, the disease is most often registered in the spring (April and May), as well as in the summer. The fewest cases of giardiasis are observed in November and October.

For many years, the danger of giardiasis was significantly underestimated. Modern scientists have no doubt that parasites pose a threat to human health. Therefore, Giardia in adults needs to be diagnosed and treated in a timely manner.

The entry point for parasites is the upper parts of the small intestine. There, mature cysts lose their protective shell and become vegetative individuals. One cyst produces 2 trophosites. With the help of flagella, they move through the intestinal mucosa, finding comfortable conditions for their existence.

After attachment to the intestinal villi, vegetative forms begin division. Colonization of the organ occurs very quickly. Just one square centimeter of the intestine can contain up to 1 ml of individuals. The maximum number of Giardia occurs in the upper part of the small intestine. It is here that parasites have optimal conditions for accessing the spaces between the villi, from which they absorb carbohydrates, fats, proteins, mineral salts and other nutrients. In later periods, Giardia descends into the middle and terminal sections of the small intestine.

Those vegetative forms of Giardia that are not attached to the villi descend into the large intestine, where they become cysts. After which the cysts absorb flagella and become covered with a protective shell. This process is facilitated as much as possible under the condition of normal intestinal motility. If it is accelerated, which is observed with diarrhea, the vegetative forms of Giardia do not have enough time to form full-fledged cysts, and they emerge into the external environment insufficiently protected. As was said, such vegetations die very quickly outside the human body.

For a long time, there was a belief that Giardia can parasitize the bile ducts. However, it has been proven that bile in high concentrations is destructive for these parasites. They lose their vitality in it in a few seconds.

Factors that contribute to massive outbreaks of giardiasis among the population are:

Fecal pollution of the environment;
High crowding;
Low level of development of sanitary and hygienic skills among the population;
Insufficient or poor-quality purification of drinking water before it enters the water supply system.

Naturally, the risks of invasion for an adult increase if one or more children under the age of 10 live in the house.

Forecast

With giardiasis, the prognosis for the patient is favorable. In most cases, the infection goes away on its own; in others, the patient is treated with antiprotozoal drugs. It is worth remembering that sometimes after recovery, symptoms of lactase deficiency may remain for some time.

Prevention of giardiasis

Giardia infection cannot be prevented with drugs or a vaccine. However, there are preventive measures that significantly reduce the risk of infection.

Wash your hands thoroughly and treat them with antiseptics.
Purify water from natural sources. Avoid drinking untreated water from shallow wells, lakes, rivers, springs, ponds and streams. Heat treatment at temperatures above 70°C for 10 minutes is acceptable.
Wash raw fruits and vegetables with clean drinking water. It is better to peel the fruit before eating. In countries where fruits and vegetables may come into contact with contaminated water, it is recommended to avoid consuming them altogether.
Try not to swallow water when swimming in pools or open water sources.
Use bottled water for drinking and brushing your teeth. Avoid ice in cafes and restaurants.
Safe sex. Don't have oral sex immediately after anal sex.

The listed preventive measures are especially relevant in endemic areas (many countries in Asia, Africa, Latin America).

Is Giardia transmitted?

Is Giardia transmitted from person to person?
Giardia is transmitted from person to person.
Is Giardia transmitted through kissing or saliva?
Transmission of Giardia through a kiss is theoretically possible, provided that parasite cysts are present in the person’s saliva during the kiss.
Is Giardia transmitted from cats to humans?
Giardia can be transmitted from cats to humans.
Can Giardia be seen in feces?
It is impossible to see Giardia in feces on your own, since their size is very small. Therefore, parasites in feces can only be visualized under a microscope.

Symptoms of giardiasis

Symptoms of giardiasis are very often absent altogether. An asymptomatic course of the disease is observed in 65% of patients. If the clinical picture manifests itself clearly, then most often this is due to either massive invasion, or disruption of the human immune system, or the entry into the body of certain strains of infection that are highly virulent. For example, in people with HIV, the disease is much more severe than in healthy patients. Periods of remission are followed by frequent periods of exacerbation.

The following classification of giardiasis is considered to be the most complete:

Asymptomatic carriage of giardiasis
Severe symptoms of giardiasis. Severe symptoms of the disease include:
Hepatobiliary form in which the symptoms of cholecystitis and biliary dyskinesia come to the fore.
Giardiasis as a concomitant disease.

Based on a study of the symptoms of giardiasis in people of different age groups, Zalipaeva T.L. identified the following main syndromes of the disease:

Dyspeptic syndrome, which is the leading one and is present in the clinical picture of 81.5% of all patients.
Pain syndrome, which is characteristic of 76.9% of all infected people.
Astheno-neurotic syndrome with increased fatigue, irritability and headaches. Similar symptoms are observed in 64.8% of patients.
Allergic reactions of the body. Most often, patients experience atopic dermatitis. This syndrome occurs in 15.7% of cases.

It is noted that similar syndromes may be present in any of the listed clinical forms of giardiasis. As for laboratory data, with giardiasis, 31.5% of patients experience an increase in the number of eosinophils by 5-7%.

Symptoms of giardiasis in the acute stage

The acute stage of giardiasis is characterized by the following symptoms:

Nausea, lack of appetite, frequent belching.
Bloating, flatulence, rumbling in the intestines, excessive gas production.
Loss of body weight.
Painful sensations occur in the area of the right hypochondrium and in the peri-umbilical zone. At the same time, every second patient reports pain in the navel area, and about 15% of people report pain in the right hypochondrium. Painful sensations are very often associated with food intake, so they are not associated with giardiasis.
A bitter or sour taste appears in the mouth.
Diarrhea may develop. In this case, bowel movements become more frequent and can occur from 3 to 5 times a day. If at the beginning of the acute period the stool is liquid and watery, then later it thickens and becomes greasy.
Salivation increases.
There is rapid fatigue and unexplained weakness.
Performance deteriorates.
Skin rashes appear.
Avitaminosis. Its symptoms boil down to increased brittleness of nails, hair loss, peeling of the skin, etc.

The acute period lasts for five days, but can sometimes last for a week. If a person has an immunodeficiency, then the acute period of giardiasis is usually longer, and all of the listed symptoms are fully manifested.

Sometimes in the acute phase symptoms of biliary dyskinesia occur. If in children with giardiasis the body temperature rises and symptoms of intoxication increase, then for adult patients such a clinical picture is not typical.

After a week, giardiasis either goes away on its own or becomes chronic.

Symptoms of giardiasis in the chronic stage

Symptoms indicating a chronic form of giardiasis in adults:

Disorders of the digestive system. The patient's stool becomes unstable, frequent constipation is replaced by equally frequent diarrhea. Appetite remains reduced, and bloating and rumbling in the intestines are periodically disturbing.
The general well-being of a person suffers. Often headaches occur, excessive drowsiness and irritability appear. This condition leads to deterioration in working ability.
Skin color deteriorates and mild jaundice may develop. First of all, the neck, face, axillary folds, and abdomen acquire a jaundiced tint.
Skin rashes begin to bother the patient more and more often, even if the person did not suffer from allergies before. Dermatitis or urticaria may occur. Quincke's edema in adults against the background of giardiasis occurs extremely rarely; asthmatic bronchitis or bronchial asthma develops more often. The main features of allergies against the background of giardiasis are: long-term course, lack of response to taking antihistamines, frequent relapses.
Urticaria is especially difficult in adults against the background of giardiasis, disrupting the patient’s quality of life. Moreover, it occurs without any background errors in nutrition, without taking medications, etc. Very often, urticaria is accompanied by symptoms of blepharitis.
Chronic giardiasis is characterized by keratosis pilaris with the appearance of pinpoint swellings on the skin. The skin of the shoulders is predominantly affected. It becomes covered with a rough crust or white round plaques, prone to increased peeling.
Giardiasis is associated with xerosis in which the patient's heels peel, especially in the cold season.
Isolated damage to the palms and feet is possible, when the skin begins to peel off from the tips of the phalanges. The fingers resemble those of an old man. This process, as a rule, does not reach the palms.
The mucous membrane of the oral cavity suffers. A person often develops aphthous stomatitis, jams appear in the corners of the mouth, and the border of the lips becomes inflamed.
Hair becomes thinner, becomes brittle, and loses its natural shine.
The patient continues to lose weight.

If Giardia parasitizes an adult for a long time, then signs of immunosuppression and symptoms of intoxication will be observed. At the same time, the lymph nodes periodically become inflamed, the tonsils become enlarged, and the body temperature rises to subfebrile levels.

Another indirect sign of giardiasis in adults is intolerance to whole cow's milk, since these parasites infect the enterocytes responsible for the hydrolysis of carbohydrate components of food. This also explains the increased gas formation in the intestines.

Consequences of giardiasis

The consequences of giardiasis occur with a long course of the disease. First of all, the human immune system suffers, which provokes constant viral and bacterial diseases.

Secondly, the risks of developing chronic diseases of the digestive system increase, which cannot be eliminated even after giardiasis is cured. The development of acute pancreatitis, cholecystitis, gastroduodenitis, ulcerative lesions of the stomach and intestines is possible.

Thirdly, with parasitic infestation, the patient suffers from allergic reactions, which can result in bronchial asthma. Its symptoms can also persist throughout life, even if giardiasis is cured.

Classification

If you want to dive deeper into the topic, we present for you the classification of giardiasis developed by the Society of Pediatric Gastroenterologists of Russia⁴.

According to symptoms:

typical (with the symptoms described above);
atypical. This includes asymptomatic carriage of the microorganism (a disease without manifestations) and erased clinical forms - minimal symptoms that do not reflect the classic form of the disease.

According to clinical form:

with predominantly damage to the digestive system (symptoms from the stomach, intestines, liver damage);
with damage to other organs and systems (this includes forms with pronounced intoxication syndrome, asthenoneurotic syndrome (pronounced weight loss of the patient), anemic syndrome);
mixed forms.

According to the course of the disease:

acute giardiasis (symptoms last up to 1 month);
subacute (from 1 to 3 months);
chronic (more than 3 months).

Based on the presence of complications, complicated and uncomplicated giardiasis are distinguished.

Diagnostics

Diagnosis of Giardia in adults must be carried out according to the following indications:

Diarrhea, which is persistent and does not find viral, autoimmune or bacterial confirmation.
Allergic and allergy-like diseases of the respiratory tract (bronchial asthma, obstructive bronchitis) and skin (urticaria, eczema, dermatitis, etc.).
Increase in eosinophils in the blood.
Prolonged increase in body temperature to subfebrile levels.
Having confirmed contact with an infected person.

Visual markers of patients with giardiasis are: dry skin, soreness of the mesogastrium, bloating, coated tongue, possible enlargement of the liver.

Modern diagnosis of Giardia in adults includes the following set of possible measures:

Microscopic examination of stool.
PCR stool.
Stool ELISA using rapid tests.
PCR of duodenal contents of the duodenum.
Blood ELISA for giardiasis.

The basic diagnostic method is microscopic examination of stool. It must be carried out at least 3 times, especially if there is a suspicion of the presence of parasites in the human body. Giardia cysts are most often found in feces.

For the result to be as reliable as possible, the following conditions must be met:

On the eve of the test, it is advisable to avoid eating rough food, mushrooms and liver, so as not to complicate the visualization of parasites;
Do not use an enema to collect biomaterial;
Stop taking sorbents and antibiotics, or wait 2 weeks after the last dose of the drug;
Feces are collected in a sterile container;
The stool must be fresh and delivered to the laboratory within an hour.

Additional methods for diagnosing giardiasis in adults can include studies such as: general blood and urine analysis, blood biochemistry, coprogram and stool culture for microflora, test for lactase deficiency, FGDS, etc.

Treatment of giardiasis in adults

Treatment of Giardia in adults is carried out by an infectious disease specialist.

Before deciding on therapy, the doctor must take into account such aspects as:

The severity of the symptoms of the disease;
Duration of presence of Giardia in the intestines;
Presence of concomitant diseases.

It is equally important to try to determine the source of the invasion in order to prevent reinfection. Treatment should not be started by taking antiprotozoal drugs, as this will exacerbate the symptoms of the disease and may provoke a reactive response from the body.

Therefore, treatment of Giardia in adults is carried out in stages:

Preparatory stage before treatment of giardiasis.
At the preparatory stage, it is necessary to try to mechanically remove the maximum amount of Giardia from the intestines, as well as remove intoxication from the body. During this time, the patient must adhere to a dietary diet.
To do this, the patient must follow the following recommendations:
Eat foods rich in fiber;
Eat protein foods;
Avoid whole milk and limit fat intake;
Eat according to a schedule, switch to fractional meals (5-6 times a day);
Drink more fluids, giving preference to sour fruit drinks and choleretic decoctions.

Supplementing the diet is the intake of enterosorbents, choleretic drugs, antihistamines and digestive enzymes. In this way, conditions will be created in the intestines that are unfavorable for the proliferation of parasites and the rate of their division will be significantly reduced.

The use of antiparasitic drugs against Giardia.
The second stage of antiparasitic therapy takes 5-10 days.
All medications are prescribed by the attending physician, since almost all drugs have contraindications and side effects. Drugs and dosages for the treatment of children are selected with special care, trying to minimize the toxic effect of drugs.
Restoration of the body after treatment of giardiasis.
The final stage of treatment is aimed at increasing the patient’s immunity and normalizing the intestinal microflora. To do this, he is prescribed vitamin and mineral complexes, intestinal bacteria, and enzyme preparations.

As a rule, the prognosis for giardiasis in adults is quite favorable. If the patient strictly follows all the doctor’s instructions, recovery is observed in 92-95% of cases. However, reinfection cannot be ruled out, so the patient should remain under clinical observation for another 3-6 months. During this time, it must be examined at least 2 times.

Growth and reproduction of Giardia

Reproduction of Giardia occurs in the small intestine, in places of their greatest accumulation, through constant continuous pair division of vegetative individuals. In general, the entire division process takes no more than 20 minutes, which quickly leads to the colonization of the intestines by this species of protozoa. Reproduction of vegetative individuals and cyst formation are independent processes.

The active life activity and high rate of reproduction of the parasite on the intestinal wall directly depends on the state of the digestive system. Starvation of the host and food rich in protein sharply reduces the number of persistent individuals. Excess carbohydrates in the diet and the release of a small amount of bile into the intestinal lumen, on the contrary, stimulate the division of Giardia.

The reproduction of the protozoan occurs the faster, the more active the processes of parietal digestion are, this explains the wide prevalence of infection among children. Giardiasis in adults is often layered with pathology of the stomach and intestines, causing an increase in the rate of parietal digestion. Favorable conditions for the growth of the parasite are a decrease in the acidity of gastric juice or a history of removal of part of the stomach.

Prevention of Giardia in adults

Prevention of Giardia in adults comes down to the following measures:

Timely detection of cases of invasion with subsequent high-quality treatment of patients with giardiasis.
Following strict hygiene rules with regular hand washing.
Use boiled or bottled water for drinking.
Preventing fecal matter from entering the environment.
Compliance with sanitary and hygienic measures in food and water supply institutions.
Regular examination of people at risk for giardiasis.
Conducting sanitary education work among the population by local authorities.

There is no vaccine for giardiasis, and the immunity that is developed after an illness is not very stable. Therefore, the risk of reinvasion remains high.

Infection through pets

Pets are susceptible to the disease, just like people. They are more often affected by infection. Owners forget to diagnose and treat their pets. Infection with a dangerous disease occurs.

Children and pet trainers can often become infected. The simplest inhabitants from the fur end up on the hands and gastrointestinal tract. The main reason is non-compliance with personal hygiene rules.

Infection is avoided by examining the pet for possible presence in the fur. Close contact between the animal and the baby should not be allowed.

A special approach to walking a dog is needed. Pet excrement must be removed without coming into contact with human skin. The rule applies to cats - place the tray out of the reach of children. It is necessary to limit the access of pets to human food products.