Ascaris Development Cycle: Scheme, Incubation Period And How Long Parasites Live

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Ascaris Development Cycle: Scheme, Incubation Period And How Long Parasites Live
Ascaris Development Cycle: Scheme, Incubation Period And How Long Parasites Live

Video: Ascaris Development Cycle: Scheme, Incubation Period And How Long Parasites Live

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Video: Ascaris lumbricoides || Ascaris lumbricoides life cycle || Laboratory diagnosis - full explained 2023, February

The development of roundworm in the human body is considered a long process, which consists of several stages. More than 85% of the world's population are carriers of various varieties of helminths, for which a person acts as a permanent or temporary host. The peculiarities of the development cycle of roundworm differ from other types of worms, since this parasite can be in a person for several years.


  • 1 What is the life cycle of roundworm
  • 2 Features of the development of roundworm
  • 3 Stages of development of roundworm

    • 3.1 Migration stage of development
    • 3.2 Migration of larvae through various organs
    • 3.3 Re-ingestion of larvae on coughing
    • 3.4 Intestinal stage
  • 4 Development in soil
  • 5 Ways of infection

    • 5.1 Water
    • 5.2 Household
    • 5.3 Food
  • 6 What is fraught with the presence of ascaris in the human body
  • 7 Reproduction of ascaris
  • 8 Ripening roundworm eggs

    • 8.1 Temperature
    • 8.2 Soil moisture
    • 8.3 Oxygen access
  • 9 Conclusion

What is the life cycle of roundworm

It is recommended that you familiarize yourself with the roundworm life cycle and its features in advance. Most of the developmental stages of the parasite take place inside humans or animals. However, at the initial stage of its existence, the helminth develops in the ground.

The life cycle of such a helminth can be represented schematically, and this scheme is very simple:

  • egg;
  • migration stage;
  • intestinal developmental stage.

It is known that the parasite has to be in the external environment for part of its life. Roundworms are in the ground at the egg stage, when small larvae begin to develop in them. The life cycle of the worm will continue only if its eggs can get into the most suitable conditions for further development. Therefore, helminths live in the soil for only 10-20 days, after which they try to penetrate the human body.

There are many different ways of infection with ascaris. Most often, they enter the body together with unfiltered liquid, not washed or spoiled foods. After the eggs of the parasites enter the intestine of the host, larvae gradually begin to emerge from them.


For normal development, they need oxygen, so they try to get into the bloodstream in order to get through it to the respiratory system. In the lungs, juveniles develop much faster, and soon become adult larvae. However, the parasite cannot become an adult roundworm in the respiratory organs. Therefore, in order to complete the life cycle, the worm needs to enter the intestines again. For this, the helminth needs to get into the oral cavity so that a person can swallow it again. After entering the intestines, females lay eggs, which are excreted from the body along with feces.

Features of the development of roundworm

The development cycle of such a helminth is considered a gradual process, which is performed in two consecutive stages. Moreover, the duration of each of them can be 3-4 months.

The main stages in the development of roundworm include:

  • migratory;
  • intestinal.

Before the migratory stage of development of the worm begins, its eggs must fall into the ground. It is in the soil that there are optimal conditions for the development of larvae in eggs. Since the eggs of the parasites are covered with a dense shell, they easily tolerate external influences and mechanical damage. However, they do not cope well with temperature changes. Therefore, many advise, to clean the soil from helminths, water it with boiled water.


In order for the development of the worm to continue, it will have to penetrate the human digestive system. For infection, helminths use already fertilized eggs, on the surface of which there is a protective shell. They go through several stages of embryogenesis, as a result of which a small tadpole develops first, and then a mature larva appears. It can exist and develop without outside help.

Ascaris development stages

The life cycle of ascaris development consists of several stages. It is recommended to familiarize yourself with them in advance in order to better know the features of the development of helminths.

Migration stage of development

The migration stage differs from the other stages in its duration, since it is during the migration period that the main development of the worm occurs. First, the parasite enters the host's small intestine. To do this, he gradually moves through the digestive tract. In the initial stages of development, roundworms will be in the intestines. The parasite is completely protected from external mechanical influences and from gastric juice. Therefore, developing in the human body, eggs and larvae are completely safe.

Migration of larvae through various organs

When larvae emerge from the eggs, they begin to penetrate into various organs of the body. First, the pest 0.3 millimeters in size penetrates the intestinal walls. With the help of the hooks located on the head, they enter the mucous membrane and penetrate the capillaries. This helps the young to get into the circulatory system, with the help of which they enter the liver. Being in this organ, the larvae feed on erythrocytes and gradually develop.


Then parasites, through the veins, enter the ventricles of the heart. Due to the constant circulation of blood, the larvae cannot linger in the heart for a long time, and they are pushed into the lungs, in which the roundworms are for a week and a half. During this time, the larva completes the second stage of molting.

Re-swallowing of larvae when coughing

From the respiratory organs, the mature larva tries to penetrate the larynx. To do this, the parasite begins to irritate the mucous membranes of the respiratory tract, which causes inflammation in them. As a result, a person begins to cough, and the roundworm enters the larynx. Then, along with the phlegm, the worm is swallowed again and enters the digestive system.

Intestinal stage

In the larva that has entered the intestines for the second time, the incubation period begins again, which will not end until the roundworm is fully ripe. During the intestinal stage, the parasite actively moves through the small intestine in search of food masses.


For 2-3 days of active feeding, the length of the worm can increase to 30 centimeters in females and 40-45 centimeters in males. When the development of the roundworm is over, the stage of reproduction begins. Adults live in the intestines for about 2-3 years, after which they die and leave the intestines along with feces.

Development in soil

Many believe that the environment has a detrimental effect on roundworms. However, these parasites are not only able to survive in such conditions, but also to fully develop. The development of helminths in the ground begins in late spring or early autumn. In winter, due to the impact of low temperatures, development is suspended until mid-March.

Within two months, larvae begin to form in the eggs. The duration of the transition of helminths to the larval stage also depends on the characteristics of the climate and soil. Parasites develop most rapidly in warm and sunny weather in soils that are well saturated with oxygen and moisture.


It is rather difficult to unequivocally determine how many helminth eggs can live in the ground. However, most scientists claim that they live in the ground for about two years under optimal conditions. In arid regions with high temperatures, the lifespan of parasites is halved. Being in the ground, helminth eggs can get on the fruits of vegetables. Therefore, many advise, before planting plants, to spray the area with hot water to clear the soil of worms.

Infection routes

It is recommended that you familiarize yourself with common methods of infection with human roundworm in advance. There are three main routes of infection with the parasite.


Researches of scientists have repeatedly proved that the helminth is able to be stored for a long time in liquid. Thanks to this, the aquatic method of infection is considered one of the most common. Ascaris larvae and eggs are often present in rivers, ponds and lakes. Therefore, doctors do not advise drinking uncleaned liquid from water bodies, as this increases the likelihood of infection.


When drinking water with worms, the parasite immediately enters the intestines, multiplies and affects other organs.


Also, worms often penetrate the human body in a household way. Infection of children and adults is facilitated by the use of dirty dishes, on the surface of which there may be larvae. Children often become infected with ascaris due to poor hygiene or constant contact with children who rarely wash their hands. It is known that even flies can carry parasites. Having flown into the house, they spread the eggs of helminths indoors, which subsequently enter the human intestines.


Ascaris can become infected with regular consumption of raw meat products or dirty fruits with vegetables. Therefore, doctors do not advise eating food directly from the garden, as they can be contaminated. Before use, they must be washed with water.

What is fraught with the presence of ascaris in the human body

After the parasite enters the intestines, the incubation period lasts one and a half months.

At the initial stages of the development of worms in an infected person, the following signs appear, which indicate the presence of ascaris:

  • vomiting with nausea;
  • a sharp decrease in weight;
  • general weakness;
  • dizziness;
  • tingling in the intestines;
  • loss of appetite;
  • apathy.

The features of the manifestation of symptoms depend on the number of helminths and the degree of organ damage. For example, if a large number of worms are found in the liver, patients develop blood clots in their stool and develop jaundice.

It is most dangerous if the parasites have settled in the respiratory organs, since in this case it is not easy to recognize them. The symptoms that appear are reminiscent of colds, so people do not even assume that they have helminths. If you do not promptly clear the respiratory organs from worms, complications in the form of pulmonary edema may appear.

Reproduction of ascaris

Ascaris, like other types of roundworms, are dioecious. Males have special genital tubes that are responsible for removing semen. Females are distinguished by a more complex reproductive system, which consists of an ovule, uterus, vagina, seminal receptacle, and ovaries. During mating, males and females use special processes that perform the functions of the genitals. After mating, the seed enters the seminal receptacle, in which the eggs are fertilized.

Ripening roundworm eggs

The maturation of helminth eggs is influenced by several factors that must be familiarized with in advance.


The rate at which eggs ripen directly depends on the ambient temperature. Indicators of about 20-25 degrees are considered optimal. In such conditions, worms are able to grow within 10-15 days. However, they develop at temperatures of 5-10 degrees. With such indicators, the duration of their ripening increases to 30 days.


Soil moisture

Also, the duration of the development of roundworm is affected by the level of soil moisture. In the summer, the maturation of eggs is facilitated by a well-moistened ground, since low humidity can lead to their death. In spring, when the air temperature is below 30 degrees, eggs develop well even with average humidity.

Oxygen access

The amount of oxygen in the ground can also affect the maturation process. In soils that are saturated with oxygen, the development of roundworm slows down. Their eggs thrive better in dense soil with poor air permeability.


Roundworms belong to the group of helminths that penetrate the human body and poison it. It is recommended that you familiarize yourself with the description of this parasite and the main routes of infection in advance in order to prevent eggs from entering the intestines.

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