What are roundworms?
Roundworms are elongated worms that possess a large body cavity and gut. These worms typically exist as parasites. Also known as the nematodes or helminths, these parasitic worms can infect different tissues within the human body. However, the tissues of the digestive tract (especially the intestines) are the most commonly affected in roundworm infections.
Roundworms are classified within the phylum Nematoda. Out of around 500,000 different species of roundworms that are known, only about 60 species cause infections in humans.In most cases of roundworm infection, the affected individuals are not aware of being infected. It is estimated that about a third of the world’s population is infected with roundworms but the majority of infected individuals are unaware of the infection.
In most of these instances, roundworm infection is not serious. However, roundworm infection can become serious and lead to life-threatening complications in some cases.
Spread of Roundworm Infections
Roundworm infections can spread from person to person. The roundworms can enter the human body through various routes. The following are some of the most common routes of getting roundworm infection:
The most common route for spread of roundworm infection is through consumption of water and food that has been contaminated with feces containing eggs of roundworms.
- Roundworms may gain access to the bloodstream by penetrating the skin.
- Immature roundworms may also spread from person to person via insect bites.
Besides humans, other mammals can also get roundworm infections . The routes of infection are similar in all animals.
Types of Roundworms
Only a fraction of the known species of roundworms infect humans. Most roundworm infections in humans are caused by Ascaris lumbricoides, guinea worm, hookworms, filarial nematodes, whipworm, pinworm, Toxocara worms, Trichinella worms, Angiostrongylus worms, Strongyloides, Anisakis worms and Gnathostoma worms. The names of the roundworm diseases are derived from the names of the species of roundworms that cause the diseases.
For example, Ascaris lumbricoides causes ascariasis, which is the most common type of roundworm infection in humans. Filarial nematodes cause filariasis. Guinea worms are responsible for dracunculiasis and Strongyloides worms cause strongyloidiasis. Despite the various names, the spread of these infestations and subsequent disease is similar in most cases.
Read more on human intestinal worms.
Causes of Roundworm Infections
Like most parasitic worm infections, roundworm infections typically begin when an individual consumes food or water that has been contaminated with the eggs of the parasites. When the eggs reach the intestine, the larvae hatch out and penetrate the wall of the intestine. Upon entering the bloodstream through the large hepatic veins, the roundworm larvae migrate to the lungs.
These larvae are expelled through the airways and are swallowed once more. When the swallowed larvae reach the jejunum (the second part of the small intestine), they mature into adult roundworms. The food that passes through the small intestine enables the adult roundworms to sustain themselves in the gut. The adult roundworms in the intestine produce more eggs that eventually pass out through the feces.
When the water or food in the environment comes in contact with such feces, the cycle of infection begins again.The above life cycle of roundworm is typical of Ascaris lumbricoides, which causes ascariasis. This is the most common roundworm infection in humans. The life cycles of other roundworms are largely similar. However, different species of roundworms may also have certain aspects of the disease process that are distinct or unique to the species.
Diseases caused by roundworms typically require repeated exposure to parasite eggs, larvae or adult worms. This is because most parasitic worms do not complete their entire life cycle within the human host. The eggs produced by adult w orms in the human intestine need to pass out before they can hatch, mature and cause another round of infection.
Signs and Symptoms
Most cases of roundworm infections do not produce any noticeable signs and symptoms. Therefore, the majority of people with roundworm infections are not even aware of the condition. The appearance of signs and symptoms depends largely on the number of worms present in the body. The nature of signs and symptoms also depends on the location of the tissues where the worms are present.
Since most roundworms are concentrated in the gut, the majority of signs and symptoms are gastrointestinal in nature. The presence of other signs and symptoms may indicate infection in other tissues. The following are some of the common signs and symptoms produced by roundworm infections.
The most likely gastrointestinal signs and symptoms produced by roundworm infections are nausea, vomiting, abdominal pain, diarrhea, bloody stools, and presence of visible worms in the stool.
Infection in the lungs can produce symptoms such as wheezing, coughing, and breathing difficulties.
Fatigue, weight loss, fever, stunted growth and a general feeling of malaise are some other signs and symptoms of roundworm infections. In some roundworm infections, signs and symptoms affecting the nerves, skin and eyes may also be present. For example, infection with the filarial worm, Onchocerca volvulus, causes onchocerciasis that is characterized by a serious loss of vision.
Therefore, this disease is also referred to as river blindness. An increase in the number of worms in the intestine could also cause entangling of the worms and obstruction of the intestinal lumen. In some cases, worms may even try to exit through the nasal passages.
Complications of Roundworm Disease
Most roundworm infections in humans are not serious. A majority of the infections are asymptomatic. However, roundworm infections in some cases can result in potentially fatal complications. The serious complications of roundworm infection tend to occur when the infection spreads from the intestine to the other vital organs of the body.
The ensuing inflammatory response in these vital organs may then become life-threatening. The risk of fatality due to roundworm infection is relatively higher in newborn babies and immunocompromised individuals. In most people, lethal complications of roundworm infections are rare.
Diagnosis and Treatment
Diagnostic tests to detect roundworm infections include stool tests, sputum test, blood tests, x-rays and ultrasound. Stool tests are done to detect the presence of any adult worms and their eggs. Sputum tests are done to detect the presence of roundworm larvae.
Read more on pinworms.
Blood tests are done to check immune response parameters against roundworm infections (such as an increase in the number of certain white blood cells). In some cases, ultrasound or X-ray examination may also be able to detect the worms in the body. In case of onchocerciasis, a biopsy of skin lesions may be necessary for confirmed diagnosis of roundworm infection.
Once diagnosed, roundworm infections can be treated effectively through medications such as ivermectin, albendazole, mebendazole, piperazine and prednisone. Surgery is required only when a large number of worms are causing serious complications such as obstruction.