Ascariasis - a disease that belongs to the category anthroponotic and worms which is localized in the small intestine.
- 1 Etiology
- 2 cycle roundworm
- 3 Epidemiology
- 4 mechanisms of infection
- 5 Pathogenesis
- 6Clinical symptoms
- 7 Treatment
Etiology The causative agent of this helminthiasis is human ascaris (ascaris lumbricoides), a large worms dioecious.The length of an adult female is about 40 cm long, the male is about 20 cm.
ascaridiasis Infection occurs when a person swallowed them eggs, which contain the larvae.In the small intestine comes from the release of the eggs, the subsequent penetration of the intestinal wall into the blood vessel and migration on the host organism from the bloodstream.Initially, they fall into the portal vein and then to liver vessels and thence into the inferior vena cava, it is transported from the pulmonary capillaries, passing the right atrium and the pulmonary trunk.Bec
Later in the lumen of the small intestine roundworm development continues, the larvae increase in size, there is still one of their molt.Maturity helminth comes two months later.Adults roundworm live an average of about one year.
The disease is the most common worldwide helminthiasis .According to WHO figures, in the world of this disease affects about one billion people.The annual mortality rate is about one hundred thousand people.Most often the disease occurs in the camps located in areas of the tropics and subtropics: Nigeria, Congo, Brazil, Ecuador, Iraq, Malaysia, Afghanistan, Indonesia.In these regions ascariasis affects about 50% of the population.In the desert regions and in the region of eternal cold this pathology practically does not occur.
mechanisms of infection
source of infection is a person who has in his gut helminth eggs and releasing them with feces out.
During their livelihoods female worm during the day lays about 250,000 eggs.Their maximum allocation occurs in the fifth or sixth month of life, the seventh month of egg production ceases.To roundworm eggs acquired the ability to invade, they have to continue to go through a stage of development in the external environment with the necessary conditions:
- Mandatory presence of oxygen;
- not less than 80% of soil moisture;
- ambient temperature not lower than 12 and not more than 37 degrees (in cool conditions, the development takes longer than in warmer climates);
- certain period of time.
If you have the most optimal conditions (ambient temperature of about 25-30 degrees and humidity around 90%) of the eggs ripen within two weeks, after passing the first molt, the larva is formed there, which is capable of infecting humans. under favorable conditions the eggs can be maintained in a viable state for ten years.
In the temperate zone climate conditions, soil egg development begins in the spring (April-May), they do not ripen in the winter.By the summer (July), the larva becomes fully formed and capable of human infection, which can occur throughout the year, as the eggs are resistant to environmental effects, and the larvae can survive for a long time. largest number of infective larvae in the eggs produced in the soil in summer and autumn, and during this period the population in as many infected with ascariasis.
human infection can occur by using soil that is contaminated, vegetables, berries, fruit, water.Infection occurs when water enters the reservoir of waste sewage or feces from the masses located near latrines.Also, eggs can be transported mechanically by flies and cockroaches.However, most infected person comes in contact with the infected eggs of Ascaris soil, where they result in the neglect of the rules of personal hygiene into the mouth with dirty hands.In addition, a person can become infected through a variety of household goods and food products containing at his balls.And the area where the person lives, getting worming through the dust and the sole of the shoe.
foci, where an outbreak of ascariasis, as a rule, most often in rural areas or in cities where there is a source of infection, low levels of health improvement and there are domestic and economic factors that contribute to what is going on getting mature eggs toman.People who live in cities, sick ascariasis when you stay in the villages, on garden sites and summer residences, which as a fertilizer often used feces, and when consumed as food unwashed vegetables, fruits and berries, and when neglectedelementary rules of hygiene.
person's susceptibility to this disease is very high due to the fact that ascariasis occurs generate specific protective immunity.In endemic areas, the number of infected children can reach 90%.
marked difference in the pathogenetic mechanisms at different stages of migration of larvae and adult individuals .In the initial stage (migration) is released larvae ascariasis particular enzyme (hyaluronidase) which contributes to the destruction of the vessel wall penetration and the worms migrate into the bloodstream in human organs and tissues.Due to the extremely small size of the infective stage (about half a millimeter), it can only cause a small hemorrhages in the wall of the small intestine and in the liver parenchyma.At the end of their migration, the larvae grow to a length of two millimeters, penetrate into the pulmonary alveoli, the bronchial tubes and then from a larger bronchi and, in severe infestation, they cause more severe hemorrhage.It contributes to the formation in the lung tissue is thicker so-called eosinophilic inflammatory infiltrates, which are unstable in nature (volatile), may appear and disappear quickly in different areas.
then is converted into inflammatory foci of hemorrhage, which have the form typical of bronchopneumonia and acute hepatitis (with localization in the liver).During the migration stage larvae secrete a variety of metabolic and tissue decay products, which cause increased sensitivity of the body and contribute to the development of allergic processes.This leads to the formation of allergic lesion heart (myocarditis), liver (hepatitis), kidney, adrenal gland, spleen and small intestine.It is a severe complication of helminthiasis is anaphylactic shock, which often causes the patient's death.
Between parasitism in the intestine mature individuals occur continued sensitization of the human body.Underlying mechanisms of pathogenesis at intestinal stage is poisoned by toxic product released during the life of the parasite and lead to the development of disorders in the gastrointestinal tract organs, sexual organs, nervous and other systems.
also worms roundworm mechanically act on the mucous membrane of the small intestine and lead to its destruction and dysfunction: there is a change in the wall of the digestive process, absorption process, absorption of nutrients, reducing the activity of enzymes, etc.
The migration stage main clinical signs associated with increased allergic sensitivity of the organism.This period is either asymptomatic or manifest various rashes on the skin, characteristic bouts of obstruction (developing asthma).There will also be typical paroxysmal cough, which can take a protracted nature, constant runny nose, frequent acute bronchitis until the development of bronchopneumonia.In general, the analysis of the blood characterized by an increase in the number of eosinophils.During the migration period, the temperature may increase to subfebrile or high numbers, increased heart rate, reduction in blood pressure to a normal person.In addition, the process of moving larvae in the bodies tissues contributes to creating the conditions for joining a secondary infection and microbial flora, resulting in a variety of developing complications of the liver abscess, inflammation of the bile ducts, pancreas damage.
When parasitizing adult ascarids in the intestine at the intestinal stage clinical picture differs considerable variety of symptoms, which can be both weak and greatly pronounced with severe disease.In some cases, if left untreated, may lead to death .There is a disruption of normal bowel functioning of the process, there is abdominal pain, nausea and vomiting, weight loss.Perhaps the development of enterocolitis with fever.When cluster large numbers of worms can cause intestinal obstruction from peritonitis, obstruction of hepatic passages and pancreatic duct, in contact with adult worms in the respiratory tract can die from suffocation.The presence of ascariasis can also lead to brain damage (encephalopathy).
to treat helminthiasis used drugs such as mebendazole, Vermoxum, albendazole, nemozol, medamin.Dosage and administration are written in the instructions to the agent or their doctor determines. drugs are contraindicated for pregnant and breast-feeding. Two weeks after the treatment is carried out quality control of treatment: three times the study feces on eggs a worm with an interval of 14 days.