Parasitic disease
Encyclopedia
A parasitic disease is an infectious disease
caused or transmitted by a parasite
. Many parasites do not cause diseases. Parasitic diseases can affect practically all living organism
s, including plants and mammal
s. The study of parasitic diseases is called parasitology
.
Some parasites like Toxoplasma gondii
and Malaria
can cause disease directly, but other organisms can cause disease by the toxins that they produce.
function as parasites, the usage of the term "parasitic disease" is usually more restricted. The three main types of organisms causing these conditions are protozoa
(causing protozoan infection
), helminths (helminthiasis
), and ectoparasites. Protozoa and helminths are usually endoparasites (usually living inside the body of the host), while ectoparasites usually live on the surface of the host. Occasionally the definition of "parasitic disease" is restricted to diseases due to endoparasites.
or water
, bug bites, or sexual contact. Ingestion of contaminated water can produce Giardia
infections.
Parasites normally enter the body through the skin
or mouth
. Close contact with pets
can lead to parasite infestation as dogs and cats are host to many parasites. Approximately 240 diseases may be spread from animals to humans through parasites.
Other risks that can lead people to get parasites are walking barefeet, inadequate disposal of faeces, lack of hygiene
, close contact with someone who carries specific parasites, eating undercooked or exotic foods.
or a hormone deficiency. Some of the symptoms caused by several worm infestation can include itching affecting the anus
or the vaginal area, abdominal pain
, weight loss
, increased appetite
, bowel obstruction
s, diarrhea
and vomiting
eventually leading to dehydration
, sleeping problems, worms present in the vomit or stools, anemia, aching muscles or joints, general malaise, allergies
, fatigue, nervousness
. Symptoms may also be confused with pneumonia
or food poisoning.
The nematode parasites Necator americanus
and Ancylostoma duodenale
cause human hookworm
infection which leads to anaemia and protein malnutrition. This infection affects approximately 740 million people in the developing countries, including child
ren and adults, of the tropics specifically in poor rural areas located in sub-Saharan Africa
, Latin America
, South-East Asia and China
.
Chronic hookworm in children leads to impaired physical and intellectual development, school performance and attendance are reduced.
Pregnant women affected by a hookworm infection can also develop aneamia which results in negative outcomes both for the mother and the infant. Some of them are: low birth weight
, impaired milk production, as well as increased risk of death for the mother and the baby.
and mebendazole
have been the treatments administered to entire populations to control hookworm infection. However, it is a costly option and both child
ren and adult
s become reinfected within a few months after deparasitation occurs raising concerns because the treatment has to repeatedly be administered and drug resistance
may occur.
Another medication administered to kill worm infections has been pyrantel pamoate
. For some parasitic diseases there is no treatment and in the case of serious symptoms, medication intended to kill the parasite is administered, while in other cases, a symptom relief options is used.
Infectious disease
Infectious diseases, also known as communicable diseases, contagious diseases or transmissible diseases comprise clinically evident illness resulting from the infection, presence and growth of pathogenic biological agents in an individual host organism...
caused or transmitted by a parasite
Parasitism
Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...
. Many parasites do not cause diseases. Parasitic diseases can affect practically all living organism
Organism
In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole.An organism may either be unicellular or, as in the case of humans, comprise...
s, including plants and mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s. The study of parasitic diseases is called parasitology
Parasitology
Parasitology is the study of parasites, their hosts, and the relationship between them. As a biological discipline, the scope of parasitology is not determined by the organism or environment in question, but by their way of life...
.
Some parasites like Toxoplasma gondii
Toxoplasma gondii
Toxoplasma gondii is a species of parasitic protozoa in the genus Toxoplasma. The definitive host of T. gondii is the cat, but the parasite can be carried by many warm-blooded animals . Toxoplasmosis, the disease of which T...
and Malaria
Malaria
Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...
can cause disease directly, but other organisms can cause disease by the toxins that they produce.
Terminology
Although organisms such as bacteriaBacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
function as parasites, the usage of the term "parasitic disease" is usually more restricted. The three main types of organisms causing these conditions are protozoa
Protozoa
Protozoa are a diverse group of single-cells eukaryotic organisms, many of which are motile. Throughout history, protozoa have been defined as single-cell protists with animal-like behavior, e.g., movement...
(causing protozoan infection
Protozoan infection
Protozoan infections are parasitic diseases organisms formerly classified in the Kingdom Protozoa. They include organisms classified in Amoebozoa, Excavata, and Chromalveolata....
), helminths (helminthiasis
Helminthiasis
Helminthiasis is a macroparasitic disease of humans and animals in which a part of the body is infested with parasitic worms such as pinworm, roundworm, or tapeworm...
), and ectoparasites. Protozoa and helminths are usually endoparasites (usually living inside the body of the host), while ectoparasites usually live on the surface of the host. Occasionally the definition of "parasitic disease" is restricted to diseases due to endoparasites.
Causes
Mammals can get parasites from contaminated foodFood
Food is any substance consumed to provide nutritional support for the body. It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals...
or water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
, bug bites, or sexual contact. Ingestion of contaminated water can produce Giardia
Giardia
Giardia is a genus of anaerobic flagellated protozoan parasites of the phylum Metamonada in the supergroup "Excavata" that colonise and reproduce in the small intestines of several vertebrates, causing giardiasis, commonly known as Beaver fever...
infections.
Parasites normally enter the body through the skin
Skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...
or mouth
Mouth
The mouth is the first portion of the alimentary canal that receives food andsaliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth....
. Close contact with pets
PETS
PETS may be an acronym for:* Pet Travel Scheme, which allows animals to travel internationally without quarantine* Pets Evacuation and Transportation Standards Act...
can lead to parasite infestation as dogs and cats are host to many parasites. Approximately 240 diseases may be spread from animals to humans through parasites.
Other risks that can lead people to get parasites are walking barefeet, inadequate disposal of faeces, lack of hygiene
Hygiene
Hygiene refers to the set of practices perceived by a community to be associated with the preservation of health and healthy living. While in modern medical sciences there is a set of standards of hygiene recommended for different situations, what is considered hygienic or not can vary between...
, close contact with someone who carries specific parasites, eating undercooked or exotic foods.
Symptoms
Symptoms of parasites may not always be obvious. Actually, such symptoms may mimic anemiaAnemia
Anemia is a decrease in number of red blood cells or less than the normal quantity of hemoglobin in the blood. However, it can include decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin...
or a hormone deficiency. Some of the symptoms caused by several worm infestation can include itching affecting the anus
Anus
The anus is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, unwanted semi-solid matter produced during digestion, which, depending on the type of animal, may be one or more of: matter which the animal cannot digest,...
or the vaginal area, abdominal pain
Abdominal pain
Abdominal pain can be one of the symptoms associated with transient disorders or serious disease. Making a definitive diagnosis of the cause of abdominal pain can be difficult, because many diseases can result in this symptom. Abdominal pain is a common problem...
, weight loss
Weight loss
Weight loss, in the context of medicine, health or physical fitness, is a reduction of the total body mass, due to a mean loss of fluid, body fat or adipose tissue and/or lean mass, namely bone mineral deposits, muscle, tendon and other connective tissue...
, increased appetite
Appetite
The appetite is the desire to eat food, felt as hunger. Appetite exists in all higher life-forms, and serves to regulate adequate energy intake to maintain metabolic needs. It is regulated by a close interplay between the digestive tract, adipose tissue and the brain. Decreased desire to eat is...
, bowel obstruction
Bowel obstruction
Bowel obstruction is a mechanical or functional obstruction of the intestines, preventing the normal transit of the products of digestion. It can occur at any level distal to the duodenum of the small intestine and is a medical emergency...
s, diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
and vomiting
Vomiting
Vomiting is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose...
eventually leading to dehydration
Dehydration
In physiology and medicine, dehydration is defined as the excessive loss of body fluid. It is literally the removal of water from an object; however, in physiological terms, it entails a deficiency of fluid within an organism...
, sleeping problems, worms present in the vomit or stools, anemia, aching muscles or joints, general malaise, allergies
Allergy
An Allergy is a hypersensitivity disorder of the immune system. Allergic reactions occur when a person's immune system reacts to normally harmless substances in the environment. A substance that causes a reaction is called an allergen. These reactions are acquired, predictable, and rapid...
, fatigue, nervousness
Anxiety
Anxiety is a psychological and physiological state characterized by somatic, emotional, cognitive, and behavioral components. The root meaning of the word anxiety is 'to vex or trouble'; in either presence or absence of psychological stress, anxiety can create feelings of fear, worry, uneasiness,...
. Symptoms may also be confused with pneumonia
Pneumonia
Pneumonia is an inflammatory condition of the lung—especially affecting the microscopic air sacs —associated with fever, chest symptoms, and a lack of air space on a chest X-ray. Pneumonia is typically caused by an infection but there are a number of other causes...
or food poisoning.
Effects
The effects caused by parasitic diseases range from mild discomfort to death.The nematode parasites Necator americanus
Necator americanus
Necator americanus is a species of Necator. It is a class within the phylum Nematodes and commonly known as New World hookworm. It is a parasitic nematode worm that lives in the small intestine of hosts such as humans, dogs and cats. It is responsible for Necatoriasis...
and Ancylostoma duodenale
Ancylostoma duodenale
Ancylostoma duodenale is a species of the worm genus Ancylostoma. It is a parasitic nematode worm and commonly known as Old World hookworm. It lives in the small intestine of host such as humans, cats and dogs....
cause human hookworm
Hookworm
The hookworm is a parasitic nematode that lives in the small intestine of its host, which may be a mammal such as a dog, cat, or human. Two species of hookworms commonly infect humans, Ancylostoma duodenale and Necator americanus. A. duodenale predominates in the Middle East, North Africa, India...
infection which leads to anaemia and protein malnutrition. This infection affects approximately 740 million people in the developing countries, including child
Child
Biologically, a child is generally a human between the stages of birth and puberty. Some vernacular definitions of a child include the fetus, as being an unborn child. The legal definition of "child" generally refers to a minor, otherwise known as a person younger than the age of majority...
ren and adults, of the tropics specifically in poor rural areas located in sub-Saharan Africa
Sub-Saharan Africa
Sub-Saharan Africa as a geographical term refers to the area of the African continent which lies south of the Sahara. A political definition of Sub-Saharan Africa, instead, covers all African countries which are fully or partially located south of the Sahara...
, Latin America
Latin America
Latin America is a region of the Americas where Romance languages – particularly Spanish and Portuguese, and variably French – are primarily spoken. Latin America has an area of approximately 21,069,500 km² , almost 3.9% of the Earth's surface or 14.1% of its land surface area...
, South-East Asia and China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
.
Chronic hookworm in children leads to impaired physical and intellectual development, school performance and attendance are reduced.
Pregnant women affected by a hookworm infection can also develop aneamia which results in negative outcomes both for the mother and the infant. Some of them are: low birth weight
Low birth weight
Low birth weight is defined as a birth weight of a liveborn infant of less than 2,500 g. regardless of gestational age-Causes:LBW is either the result of preterm birth or of the infant being small for gestational age , or a combination of...
, impaired milk production, as well as increased risk of death for the mother and the baby.
Treatment
AlbendazoleAlbendazole
Albendazole, marketed as Albenza, Eskazole, Zentel and Andazol, is a member of the benzimidazole compounds used as a drug indicated for the treatment of a variety of worm infestations. Although this use is widespread in the United States, the U.S. Food and Drug Administration has not approved...
and mebendazole
Mebendazole
Mebendazole or MBZ is a benzimidazole drug developed by Janssen Pharmaceutica and marketed as Vermox, Ovex, Antiox, and Pripsen...
have been the treatments administered to entire populations to control hookworm infection. However, it is a costly option and both child
Child
Biologically, a child is generally a human between the stages of birth and puberty. Some vernacular definitions of a child include the fetus, as being an unborn child. The legal definition of "child" generally refers to a minor, otherwise known as a person younger than the age of majority...
ren and adult
Adult
An adult is a human being or living organism that is of relatively mature age, typically associated with sexual maturity and the attainment of reproductive age....
s become reinfected within a few months after deparasitation occurs raising concerns because the treatment has to repeatedly be administered and drug resistance
Drug resistance
Drug resistance is the reduction in effectiveness of a drug such as an antimicrobial or an antineoplastic in curing a disease or condition. When the drug is not intended to kill or inhibit a pathogen, then the term is equivalent to dosage failure or drug tolerance. More commonly, the term is used...
may occur.
Another medication administered to kill worm infections has been pyrantel pamoate
Pyrantel pamoate
Pyrantel pamoate or Pyrantel Embonate , is used as a deworming agent in the treatment of hookworms and roundworms in domesticated animals such as horses, cattle, sheep, pigs, cats, dogs, and many other species. It is a combination of pyrantel and pamoic acid...
. For some parasitic diseases there is no treatment and in the case of serious symptoms, medication intended to kill the parasite is administered, while in other cases, a symptom relief options is used.