Tapeworm Lifecycle in Humans
The life cycle of A. perfoliata requires an intermediate host for the development. The infected horses pass the tapeworm eggs onto the field where they are devoured by free-living oribatid mites. The eggs form into hatchlings inside the parasite until the bug is ingested by a brushing horse, permitting the hatchlings to be discharged into the intestine. The hatchlings complete their life cycle by connecting to the covering of the intestines where they form into grown-up tapeworms equipped for discharging eggs.
The body of a grown-up tapeworm (named the strobila) is made out of a chain of progressively mature segments (called proglottids). Each segment is independent and complete with male and female reproductive organs which create at various rates. New segments are continually being created behind the head (scolex) and they grow logically as they are pushed towards the posterior end. Mature segments are gravid (brimming with prepared eggs) and prepared to detach from the body of the tapeworm and go inside the dung into the environment, whereupon they can be eaten by oribatid mites and the cycle starts once more.
Tapeworm Lifecycle
Let us now study the tapeworm lifecycle in humans.
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Greater part of tapeworms are androgynous. A bisexual is an organism with both incomplete and complete reproductive organs. They produce gametes of both male and female genders.
1) Stage 1 – The Egg:
Tapeworm eggs are normally discharged through gravid proglottids and can make due for a considerable length of time in the environment. Creatures like steers or pigs become tainted by tapeworms when they devour vegetation.
2) Stage 2 – The Larvae:
The hatchlings tapeworm appends itself to the intestinal dividers of the host. The brought forth hatchlings migrate to the striated muscles of the intestine. Here, they form into cysticerci. A cysticerci can get by inside the host for quite a long while. Individuals get tainted with this cysticerci by consuming raw or undercooked meat.
3) Stage 3 – The Adult:
Inside the human intestine, the cysticerci produces for around 2 months and change into a grown-up tapeworm. Scolex is the foremost end of a tapeworm that has suckers and snares for appending purposes. The grown-up tapeworm produces proglottids that mature, become gravid, in the long run, detach and migrate to the anus or go in the stool.
Symptoms of Adult Tapeworm Inside the Human Body
Although the grown-up tapeworms in the intestine normally cause no symptoms, a few people experience upper stomach inconvenience, the runs, and different symptoms. Once in a while, individuals with a tapeworm can feel a bit of the worm move out through the anus or see some portion of the lace-like tapeworm in the stool. The diminutive person tapeworm is almost certain than different tapeworms to cause stomach symptoms, for example, sickness, retching, looseness of the bowels, stomach uneasiness, loss of craving, and weight reduction.
The fish tapeworm can cause sickliness in light of the fact that it ingests vitamin B12, which is fundamental for red platelets to be delivered.
Cysticercosis symptoms are brought about by cysts that structure in the brain and different organs, (for example, the spinal string, liver, lungs, and eyes). These cysts can cause serious, once in a while life-undermining symptoms years after the underlying infection, when the cysts begin to disintegrate and cause aggravation. Cysts in the brain and the tissues covering the brain (meninges) can bring about headaches, seizures, confusion, or other neurologic symptoms. Once in a while, cysts create in the eyes, at times causing the visual deficiency, or in the spinal cord, some of the time causing muscle shortcoming or loss of motion.
FAQs on Tapeworm Lifecycle
1. What is a tapeworm and to which phylum does it belong as per the NCERT syllabus?
A tapeworm is a ribbon-like parasitic flatworm that lives as an endoparasite, typically within the intestines of vertebrates. According to biological classification, it belongs to the Phylum Platyhelminthes and the Class Cestoda. Its body is adapted for a parasitic lifestyle, lacking a digestive system and absorbing nutrients directly from the host through its skin.
2. What are the main stages in the life cycle of the pork tapeworm, Taenia solium?
The life cycle of Taenia solium is digenetic, meaning it involves two hosts. The key stages are:
- Egg Stage: Fertilised eggs are passed from an infected human (primary host) through faeces.
- Oncosphere Stage: A pig (intermediate host) ingests the eggs, which hatch into larvae called oncospheres in its intestine.
- Cysticercus Stage: The oncospheres penetrate the intestinal wall, travel to the muscles, and develop into a stage called a cysticercus (or bladder worm).
- Adult Stage: A human consumes undercooked pork containing these cysticerci. In the human intestine, the cysticercus develops into an adult tapeworm, attaches to the intestinal wall with its scolex, and the cycle repeats.
3. What are the primary and secondary hosts in a tapeworm's life cycle and what is their importance?
In a tapeworm's life cycle, the hosts have distinct roles:
- The primary host (also called the definitive host) is the organism where the tapeworm reaches its adult, sexually reproductive stage. For Taenia solium, the primary host is the human.
- The secondary host (also called the intermediate host) is the organism that harbours the parasite's larval stages. For Taenia solium, the secondary host is the pig.
4. How does a human typically get infected with a tapeworm, and which specific stage is responsible for the infection?
A human contracts an intestinal tapeworm infection (taeniasis) by consuming raw or improperly cooked meat that is contaminated with the parasite's larval stage. The stage responsible for this infection is the cysticercus, often referred to as a bladder worm. When ingested, the wall of the cysticercus is digested, releasing the scolex which then attaches to the human's intestinal wall and grows into an adult worm.
5. What is the key difference between cysticercosis and taeniasis in the context of the tapeworm lifecycle?
The difference lies in the stage of the tapeworm that causes the disease. Taeniasis is the infection of the intestine by the adult tapeworm, caused by eating meat containing larvae (cysticerci). In contrast, cysticercosis is a much more serious infection of body tissues caused by accidentally ingesting the tapeworm eggs (e.g., through contaminated water or food). In this case, the human acts as an accidental intermediate host, and the larvae form cysts in muscles, eyes, or even the brain, leading to severe complications.
6. Why is a tapeworm considered a digenetic parasite? Explain with respect to its lifecycle.
A tapeworm is called a digenetic parasite because its survival and propagation depend on completing its life cycle in two different types of hosts. It cannot mature from egg to adult in a single host. For example, in Taenia solium, the adult worm lives and reproduces sexually in the human intestine (primary host), while its larval stages must develop inside a pig (secondary host). This dependence on two distinct hosts is the defining characteristic of a digenetic lifecycle.
7. What are the major anatomical parts of an adult tapeworm that are important for its survival?
The adult tapeworm has several key anatomical parts adapted for its parasitic existence:
- Scolex: The head-like structure equipped with hooks and suckers, used to firmly attach itself to the host's intestinal wall to avoid being flushed out.
- Neck: The region just behind the scolex where new segments are continuously produced.
- Proglottids: The series of body segments. They mature as they move away from the neck, developing reproductive organs. The final segments, called gravid proglottids, are filled with thousands of fertilised eggs and break off to be passed out with the host's faeces.
8. What are the common symptoms that indicate the presence of an adult tapeworm versus its larval stage in humans?
The symptoms differ significantly based on the lifecycle stage present in the human body. An adult tapeworm in the intestine (taeniasis) might cause mild or non-specific symptoms like abdominal pain, nausea, loss of appetite, or the passing of proglottids (worm segments) in the stool. However, the presence of the larval stage in tissues (cysticercosis) is far more dangerous. If larvae form cysts in the brain (neurocysticercosis), symptoms can include severe headaches, seizures, confusion, and other critical neurological issues.
