Structure life cycle and control method of Echinococcus granulosus

Structure ofEchinococcus granulosus.

Echinococcus granulosus, are also called as the hydatid worm, hyper tape-worm or dog tapeworm, is a cyclophyllid cestode that parasitizes the small intestine of canids as an adult, but which has important intermediate hosts such as livestock and humans, where it causes cystic echinococcosis, also known as hydatid disease. The adult tapeworm ranges in length from 3mm to 6 mm and has three proglottids ("segments") when intact- an immature proglottid, mature proglottid, and a gravid proglottid.The average number of eggs per gravid proglottid is 823. Like all cyclophyllideans,E.granulosus has four suckers on the scolex ("head"), andE.granulosusalso has a rostellum with hooks. Several strains ofE.granulosushave been identified, and all but two are noted to be infective in humans.

Lifecycle of E.granulosus

The life cycle ofE.granulosusinvolves dogs and wild carnivorous as a definite host for the adult tapeworm. Definitive hosts are where parasites reach maturity and reproduce. Wild or domesticated un glute's, such as sheep, serve as an intermediate host.Transitions between life stages occur as intermediate hosts.The larval stage results in the formation of echinococcal cysts are slow growing, in human and be life-threatening.Cysts may not initially cause symptoms, in some case for many years.Symptoms developed depend on the location of the cyst, but most occur in the liver, lungs, or both.

E.granulosuswas first documented in Alaska but is distributed the worldwide. It is especially prevalent in parts of Eurasia, North,and East Africa,Australia, and south America.Communities that practice sheep farming experience the highest risk of humans, but wild animals can also serve as an avenue for transmission.For example, dingoes serve as a definitive host before larvae infect sheep in the mainland of Australia.Sled dogs may expose moose or reindeer toE.granulosus in part of north America and Eurasia.

Transmission:

E.granulosusrequires two hosts types, a definitive host, and an intermediate host.The definitive host of this parasite are dogs and the intermediate host is the common sheep, however, cattle,horse, pigs,goats,and camels are also potential intermediate hosts.A human can also be an intermediate host forE.granulosus,however, this is uncommon and therefore, humans are considered as intermediate hosts.

The dog serves as the main definitive host for the dangerous parasitic, with eggs being shed itsstool.E.granulosusis ingested and attaches to the mucosa of the intestine in the definitive host and there the parasite will grow into the adult stages Adult E.granulosus release eggs within the intestine which will be transported out of the body via feces.When contaminated waste is excreted into the environment, intermediate, the host has the potential to contract the parasite by grazing in the contaminated pasture, perpetuating the cycle.

E,granulosusis transmitted from the intermediate host (sheep) to the definitive host (dogs) by frequently feeding of offal, also referred to as "variety meat" or "organ meat." Consuming offal containing E.granulosus scan lead to infection; however, infection is dependent on many factors.

The frequency of offal feedings, the prevalence of the parasites within the offal, and the age of the intermediate host are factors that affect infection pressure within the definitive host.The immunity of both the definitive and intermediate host plays a large role in the transmission of the parasite, as well as the contact rate between the intermediate and the definitive host.

The life expectancy of the parasite coupled ith the frequency of anthelminthic treatments will also play a role in the rate of infection within the host.The temperature and humidity of the environment can affect the survival ofE.graulosus.Once sheep are infected, the infection typically remains within the sheep for life. However, in other hosts, such as dogs, treatment for annihilating the parasite is possible. However, the intermediate host is assumed to retain a greater life expectancy than the definitive host.

Symptoms

A liver cyst may produce no symptoms for 10 to 20 years until it is large enough to be felt by physical examination.

Symptom include:

• Pain in the upper part of the abdomen.
• Bloody sputum.
• Chest pain
• Cough
• Fever
• Severe skin itching.

Treatment

Many patients can be treated with anti- worms medicines.

The cysts may be removed surgery, if possible.But this can be a complicated surgery.

Prevention

In areas where the disease is known to occur, healthy education and routinely removing tapeworms from the dogs can help prevent the disease.

Reference:

Aggarwal Sarita. A Text Book of Biology,New Delhi.: Madhuban Educational Books, 2011.

Bhamrah, H.S., and Kavita, Juneja. A Text Book of Invertebrates, New Delhi: Anmol Publications Pvt Ltd, 2011.

Jordan E.L. and P. S., Verma. Invertebrate Zoology, New Delhi,: S. Chand and Company Pvt. Ltd., 2011.

Kotpal, R. L.,. Modern Text Book of Zoology: Invertebrates, New Delhi, India: Rastogi Publications,2011.

http://www.biologydiscussion.com/

http://www.parasitesinhumans.org/

https://web.stanford.edu/class/

https://en.m.wikipedia.org/wiki/Echinococcus_ granulosus/