Microbiology Laboratory Turkey

Mikrobiyoloji Ile Ilgili Tüm Konuların Kısa ve Öz Anlatımları. Microbiology Lab Information.

Bu Blogda Ara(SEARCH)

MicroLab

Ascaris lumbricoides etiketine sahip kayıtlar gösteriliyor. Tüm kayıtları göster
Ascaris lumbricoides etiketine sahip kayıtlar gösteriliyor. Tüm kayıtları göster

30 Ekim 2018 Salı

Ekim 30, 2018

PARASITOLOGY

WHAT IS PARASITOLOGY?

Parasitology is a branch of biological sciences (Ecology) that deals with the study of parasites and parasitism.
There are several fields of parasitology depending on issues under investigation. 

 • Field Parasitology (Basic Biology and Life cycles of Parasites)
• Biochemical and molecular Parasitology (Cell biology of Parasites)
• Public Health Parasitology (investigating the outbreak and control of Parasitic disease)
• Spatial Parasitology (Using the Sciences of GIS and Geostatistics to understand parasite distribution and prediction)
It is therefore not uncommon to see many scientist with different background calling themselves Parasitologist. In fact if you are using parasite as models in your research, you are a Parasitologist.

A parasite is a living organism which must spend at least a part of its life cycle on another living organism (the host). This means that a parasite is an organism which is metabolically dependent on another organism for it survival.
Attribute of a parasite
➤Always smaller than the host
➤Must not necessarily kill the host
➤Require host molecules or physiological process for survival
➤May or may not cause disease (pathology)

ANIMAL ASSOCIATIONS 
The majority of animals live independently in their environmental habitats.
Between some animals, there are associations which can be broadly divided into 2 groups
1. Homogenic associations (between individual of same genotypes)
2. Heterogenetic associations (between individuals of different genotypes.

Individuals of the same species will form loose association, like communities, state, and countries, mainly for division of labour and specialization eg. Ants, bees, herd of cattles. Heterogenetic association are in general much more complex and a number of terms have been developed to  describe them. Terms such as commensalism, phoresis, symbosis, mutualism and parasitism have been widely used to for various types of heterogentic associations. 
These terms were used by earlier workers to describes heterogenetic associations among animals. The definition of these terms is still controversial as they were based on little data such behaviour and structural observations. There were no physiological or mathematical basis of such association.

Within recent years the situation has changed due to increase knowledge of animal physiology, biochemistry, molecular biology and population dynamics. Parasitism is know considered to be an ecological relationship between two population of different species (Anderson 1982). Parasites are not randomly distributed within the host population – they tend to be overdispered, i.e few hosts harbour large numbers of parasites and many hosts harbour only a few. This distribution is known as negative binomial and is typical of parasitic infection.

Dependency among animals are of several degree, therefore for an animal to be qualify as a parasite. It has must exhibit the following xter
1. Metabolic dependence: A parasite is considered here to be an organism that is metabolically dependent directly or indirectly on the hosts to some degree. 
2. Developmental stimuli: A parasites must be able to recognised the environment of host which can trigger developmental process
3. Nutritional dependence: The host is source of food for the parasites
4. Digestive enzymes: The Parasites has evolve enzymes that can digest host complex molecules.
5. Control of maturation: The parasite need the host to control its development.



0
By on Hiç yorum yok:
Etiketler: , , , , , , , , , , , , , ,

16 Ekim 2018 Salı

Ekim 16, 2018

Ascaris lumbricoides

Ascaris lumbricoides


The number of people in the world with Ascaris is probably second only to those infected with the pinworm, Enterobius vermicularis. Ascaris was well known in Roman times as Lumbricus teres (confused with the common earthworm) and has probably been infecting humans for thousands of years. It is prevalent in moist, warm climates, but can also survive in the temperate zones.

Life Cycle and Morphology
The adult worms are cylindrical, with a tapering anterior end. They are the largest of the common nematode parasites of humans; females measure 20 to 35 cm long and the males are 15 to 31 cm long, with a curved posterior end. Also, the three welldeveloped lips are characteristic of this group. Infection in humans is acquired through ingestion of the embryonated eggs from contaminated soil. On ingestion, the eggs hatch in the stomach and duodenum, where the larvae actively penetrate the intestinal wall; they are then carried to the right heart via the hepatic portal circulation. Then the larvae are carried into the pulmonary circulation, where they are filtered out by the capillaries. After approximately 10 days in the lung, the larvae break into the alveoli, migrate via the bronchi until they reach the trachea and pharynx, and are then swallowed. 

 The worms then mature and mate in the intestine, with the eventual production of eggs which are passed in the stool. The entire developmental process from egg ingestion to egg passage from the adult female takes from 8 to 12 weeks. During her life span, egg deposition may reach a total of 27,000,000 eggs. Both unfertilized and fertilized eggs are passed. Often only female worms are recovered from the intestine. Fertilized eggs will become infective within 2 weeks if they are in moist, warm soil where they may remain viable for months or even years. The fertilized egg is broadly oval, with a thick, mammilated coat, usually bile-stained  a golden brown. These eggs measure up to 75 µm long and 50 µm wide. Unfertilized eggs are usually more oval, measure up to 90 µm long, and may have a pronounced mammilated coat or an extremely minimal mammilated layer. Often both types of eggs are found in the same stool specimen. The total absence of fertilized eggs means only female worms are present in the intestine. 



Clinical Disease 
Pathogenesis caused by Ascaris infections is attributed to (1) the host's immune response, (2) effects of larval migration, (3) mechanical effects of the adult worms, and (4) nutritional deficiencies due to the presence of the adult worms. Although the initial passage of larvae through the liver and lungs usually elicits no symptoms, there can be signs of pneumonitis if the number of larvae is quite large. When the larvae break out of the lung tissue and into the alveoli, there may be some bronchial epithelium damage. With reinfection and subsequent  arval migrations, there may be intense tissue reactions, even with small numbers of larvae. There may be pronounced tissue reaction around the larvae in the liver and lung with infiltration of eosinophils, macrophages, and epithelioid cells. This has been called Ascaris pneumonitis and is accompanied by an allergic reaction consisting of dyspnea, a dry or productive cough, wheezing or coarse rales, fever (39.9-40.0°C), transient eosinophilia, and a chest xray suggestive of viral pneumonia. This picture of transient pulmonary infiltrates, clearing within a couple of weeks, and associated with peripheral eosinophilia is frequently called Loeffler's syndrome. In addition to eosinophils and CharcotLeyden crystals, the sputum may also contain larvae. Asthma and urticaria may continue during the intestinal phase of ascariasis. 

 The presence of the adult worms in the intestine usually causes no difficulties unless the form burden is very heavy; however, due to the tendency of the adult worms to migrate, even a ingle worm can cause serious squeal. Worm migration may occur as a result of stimuli such as fever (usually over 38.9 (°C), the use of general anesthesia, or other abnormal conditions. This migration may result in intestinal blockage; entry into the bile duct, pancreatic duct, or other small spaces; or entry into the liver or peritoneal cavity. They can also migrate out of the anus or come out the mouth or nose. Other body sites have been involved such as the kidney, appendix, or pleural cavity. In children, particularly those under the age of 5, there may be severe nutritional impairment related to the worm burden. Directly measurable effects would include increased fecal nitrogen and fecal fat, and impaired carbohydrate absorption, all of which would return to normal with elimination of the adult worms. Worms can also be spontaneously passed without any therapy.


 Diagnosis
In the larval migration phase of the infection, diagnosis can be made by finding the larvae in sputum or in gastric washings. The typical Loeffler's syndrome is more likely to be seen in areas where transmission is highly seasonal. During the intestinal phase, the diagnosis can be made by finding the eggs (unfertilized or fertilized) or adult worms in the stool. The eggs are most easily seen on a direct wet smear or a wet preparation of the concentration sediment. Unfertilized Ascaris eggs will not float using the zinc sulfate flotation concentration method (eggs too heavy). Also, if too much iodine is added to the wet preparations, the eggs may look like very dark debris. Eggs may be very difficult to identify on a permanent stained smear due to stain retention and asymmetrical shape. Intestinal disease can often be diagnosed from radiographic studies of the gastrointestinal tract where the worm intestinal tract may be visualized. This may be particularly obvious when two worms are lying parallel, like "trolly car lines". Other involved body sites would present specific symptoms indicative of bowel obstruction, biliary or pancreatic duct blockage, appendicitis, or peritonitis. Therapeutic measures would be related to specific symptoms and involved areas.

Ascaris lumbricoides —LABORATORY DIAGNOSIS
1. Both fertilized and unfertilized eggs can easily be recovered using the sedimentation concentration. (Unfertilized eggs will not float using zinc sulfate flotation concentration.)
2. Because of the potential problems caused by migration of the adult worms, patients who are undergoing elective surgery and general anesthetic should be checked for the presence of Ascaris if there is any possible exposure history (some anesthetics stimulate the worms to migrate). Usually a single stool examination will suffice to rule out the infection.
3. Larvae could be recovered from sputum (larval migration through the lungs); however, this is not a common finding.
4. Eggs may be very difficult to recognize on a permanent stained smear. They will usually be very darkly stained and may be mistaken for debris.



1
By on 1 yorum:
Etiketler: , , , , , , , , , , , , , , ,