Ascaris Lumbricoides - Group6.docx

REYES, SAMANTHA L. (GROUP 6) 1. Describe the morphology of your sample worm (male or female) from your dissection, upload the photograph with measurement using ruler. Just like any other Ascaris lumbricoides male, the posterior end of our sample is hooked or curved. If being compared to other samples obtained by our classmates, it is shorter and thinner.

2. What is the distinct characteristic of female and male Ascaris? FEMALE MALE 20-40 cm long 15-30 cm long. thicker thinner posterior end: straight posterior end: hooked posterior opening: posterior opening: lack structures it has pineal spicules, or spine-like extensions, near its opening. It will also have papillae, or bump-like protrusions, in front and behind this opening. have a large reproductive opening on the lack such opening. posterior third of its body has two reproductive organ tubes joining to have one straight tube. form a Y

3. Describe the ova/egg of Ascaris, upload the photograph with magnification using LPO and HPO. What is the capacity of uterus to produce fertilized egg per day?

These are some of the eggs that we found in our male Ascaris. Despite of our sample being a male, presence of eggs can still be seen and that’s because of their mating. However, it’s much smaller compared to the eggs of the female Ascaris. For the female Ascaris, they are enable to produce 200,000-240,000 eggs per day.

4. What is the purpose of staining the egg/ova? The staining of the ova or egg helps to identify what kind of parasite invades the person. It emphasizes the staining characteristics of different ova found in the stool to avoid misidentification. In the case of Ascaris, it also helps to identify if the egg is fertilized or not. 5. When symptoms do occur, they relate either to the larval migration stage or to the adult worm intestinal stage? Discuss briefly the pathophysiologic mechanisms include a. direct tissue damage The majority of infections with A. lumbricoides are asymptomatic. However, the burden of symptomatic disease worldwide is still relatively high because of the high prevalence of disease. Clinical disease is largely restricted to individuals with a high worm load [1]. When symptoms do occur, they relate either to the larval migration stage or to the adult worm intestinal stage. Part of the success of this parasite is that the migration, maturation, and subsequent dwelling in the intestine usually cause minimal tissue damage (ie, the most biologically successful parasites do not significantly harm the host). b. The immunologic response of the host to infection with larvae, eggs or adult worms In one scenario, parasites of the primary infection induce an immune response that, while incapable of killing them, is nevertheless able to kill incoming parasites that may cause a superinfection. This requires that the adult parasites, but not invasive larval stages, express immune evasion mechanisms and that common Ag be shared between the different stages. A second explanation is that the primary infection alters the anatomy or physiology of the host in

such a way that it becomes more difficult for incoming larval organisms to establish infection in the appropriate niche.

Ref: https://iai.asm.org/content/70/2/427 https://www.hindawi.com/journals/bmri/2010/428593/ https://www.sciencedirect.com/topics/medicine-and-dentistry/ascaris-lumbricoides https://web.stanford.edu/group/parasites/ParaSites2005/Ascaris/JLora_ParaSite.html