parasite

Phylum Nematoda Class SecernentaOrder AscaridiaFamily AscarididaeGenus AscarisA. lumbericoides

Introduction As.Lumbricoides is the giant roundworm of human, belonging tothe phylum Nematode. It is the largest and most common parasiticworm in human

It is responsible for the diseasecalled ascariasis in small intestine of human

One sixth of the human population is estimated to be infected by thisparasite. Ascariasis is prevalent worldwide and more so in Tropicaland Subtropical countries


Ascariasis can occur at all ages, but is moreprevalent in 5-9 years old group. The incidence is higher in poor ruralpopulation.

Habitat:-The adult worm lives in the small intestine of human

Morphology :-The adult worm is the largest round worm parasitizing the human intestinal tract. It is elongeted, cylindrical, and tapers both anteriorly &posteriorly to relatively blunt conical ends. The head is provided with three fleshy lips .



The digestive &reproductive organs float inside the body cavity which contain an irritating allergic fluid .The irritant action is due to the presence of atoxin called a scarone or a scarase which is probably of the nature of primary albomenoses

Egg:The fertilized egg of Ascaris lumbricoides at the time of oviposition is spherical or sub-spherical,measures 65-75umby35-50um &consists of the following observable structures


1-A coarsely granular ,spherical ovumthat usually does not completely fill the shell.2-A thin innermost membrane that is highly impermeable.3-A relatively thick,colorless middle layer that is smooth on both inner &outer surfaces .4-An outer most ,coarsely mammilated


Female worms without males produce infertile eggs that are markedly subspherical (88um by38-44um),internally they contain a mass of disorganized granules that completely fill the shell

Infections of Ascaris are diagnosed by:1-finding characteristic eggs in the feces of the infected host.

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2-the presence of three large lips, a characteristic of ascarids.

Ascaris lumbricoides, fertilized egg.

Ascaris lumbricoides, fertilized egg.

An example of an unfertilized A. lumbricoides egg. (Original image from: Atlas of Medical Parasitology.)



A "decorticated," fertilized, Ascaris lumbricoides. (Original image from: Atlas of Medical Parasitology

Eggs of Ascaris suum. A. suum is a common parasite of pigs. The eggs are virtually indistinguishable from those of A.lumbricoides. (Original image from Oklahoma State University, College of Veterinary Medicine.)

Female and male Ascaris lumbricoides; the female measures

female Ascaris lumbricoides. Females of this species can measure over 16 inches long. This specimen was passed by a young girl in Florida.

Note : up stream movement this movement for A. lumbericoides through mouth or nose.

Note: some times the infected man may die due to this irritation action after changing to anaphylatic or HSR.

Different betweenfertilized & unfertilized eggs of A.lumbericoides

Lecture 2 Dr. Jabar Etaby Hookworms Introduction Patients with hookworm infection often are asymptomatic; however, chronic hookworm infection is a common cause of moderate and severe hypochromic, microcytic anemia

in people living in tropical developing countries, and heavy infection can cause hypoproteinemia with edema.


Larvae and eggs survive in loose, sandy, moist, shady, well-aerated, warm soil (optimal temperature 23°C–33°C) [73°F–91°F]).

After contact with contaminated soil, initial skin penetration of larvae, often involving the feet, can cause a stinging


Pneumonitis associated with migrating larvae is uncommon and usually mild, except in heavy infections.

Colicky abdominal pain, nausea, and/or diarrhea and marked eosinophilia can develop 4 to 6 weeks after exposure


Blood loss secondary to hookworm infection develops 10 to 12 weeks after initial infection and symptoms related to serious iron-deficiency anemia can develop in long-standing moderate or heavy hookworm infections.

Mixed infections are common. Both are roundworms (nematodes) with similar life cycles.

Ancylostoma spp. and Necator spp. (hookworms)There are many species of hookworms that infect mammals

The juvenile worm migrates through the host'sbody and finally ends up in the host's small intestine where it grows to sexual maturity.

The presence of hookworms canbe demonstrated by finding the characteristic eggs in the feces; the eggs can not, however, be differentiated to species


DIAGNOSTIC TESTS


1- Microscopic demonstration of hookworm eggs in feces is diagnostic.& Adult worms or larvae rarely are seen.

2-Approximately 5 to 8 weeks are required after infection for eggs to appear in feces.

3-A direct stool smear with saline solution or potassium iodide saturated with iodine is adequate for diagnosis of heavy hookworm infection;

4-light infections require concentration techniques. Quantification techniques

5-, Kato-Katz, Beaver direct smear, or Stoll egg-counting techniques) to determine the clinical significance of infection and the response to treatment may be available from state or reference laboratories.


CONTROL MEASURES Sanitary disposal of feces to prevent contamination of soil is necessary in areas with endemic infection


Treatment of all known infected people and screening of high-risk groups (ie, children and agricultural workers) in areas with endemic infection can help decrease environmental contamination.


. Wearing shoes may not be fully protective, because cutaneous exposure to hookworm larvae over the entire body surface of children could result in infection.



A histological section of a hookworm in the host's small intestine. Original image copyrighted and provided byDr. A.W.Shostak, and used with permission