Helminthiasis

What is Helminthiasis?

The term “helminths” is Greek for worm and refers to parasites that can infect humans. These parasites are often categorized as either heirlooms or souvenirs. Heirlooms are parasites inherited from our ancestors in Africa, whereas souvenirs are parasites that we acquired from animals through our evolution, migration, and farming practices. In developing countries, helminth infections are the most common infections in human beings. According to estimates, about one-fourth of the world’s population, nearly 2 billion people, are affected by these helminth parasites. These infections are particularly prevalent in children and are a significant health burden in developing countries.

Two main types of helminths exist: nematodes and platyhelminths. Nematodes, also known as roundworms, include soil-transmitted helminths and filarial worms that can lead to medical conditions such as lymphatic filariasis (LF) and onchocerciasis. The second group, platyhelminths, also known as flatworms, consists of flukes or schistosomes and tapeworms like the pork tapeworm, which can cause cysticercosis. Flukes are technically called trematodes, and tapeworms are called cestodes. Soil-transmitted helminths are a roundworm (Ascaris lumbricoides), whipworm (Trichuris trichiura), and hookworm (Ancylostoma duodenale and Necator americanus).

The soil-transmitted helminths (STHs) can infect humans via contaminated soil that contains the eggs of A. lumbricoides and T. trichiura. Some helminths, such as hookworm larvae, can penetrate the skin directly. Helminth diseases are considered neglected tropical diseases because they often slowly affect growth and development over time. Furthermore, the study into these diseases is given less than 1% of the global research budget.

What Causes Helminthiasis?

Infections from intestinal parasites can often lead to illness and sometimes death, particularly in children. These infections, known as helminthiasis, are more likely to occur in rural areas, among people with a low income, in places with bad sanitation, where clean water is hard to come by, in people with poor personal hygiene (like not trimming their nails regularly), crowded living spaces, lack of education, limited access to healthcare, and inadequate living conditions.

Two parasites, A. lumbricoides and T. trichiura, are spread when someone swallows the parasite’s eggs that have been in feces. The adult Ascaris worm looks like a long cylinder, and its babies, or larvae, can even travel into the lungs. However, T. trichiuria can’t do this.

Another two parasites, A. duodenale and N. americanus, get into someone by penetrating their skin, then make their way to the lungs, and finally to the intestines. N americanus is more commonly found around the world, compared to A. duodenale. Another parasite, S. stercoralis, can also get into someone orally or through the skin. Poor hygiene from the mother or caregiver is one of the highest risk factors for getting these types of parasites for preschool children.

The parasite that causes schistosomiasis typically comes from contact with infected freshwater snails, usually during swimming or washing. This infection can cause a long-term inflammatory reaction that creates “oxygen-free radicals”. These radicals can cause various cell mutations and create N-nitrosamines, a type of carcinogen that can cause bladder cancer and scar tissue in the liver’s portal tract.

A different type of infection, diphyllobothriasis, usually happens when someone eats fish infected with the larva of the D. Latum, also known as a fish tapeworm.

Risk Factors and Frequency for Helminthiasis

Research indicates that within the USA, between 1.3 to 2.8 million people show signs of infection with Toxocara species. Meanwhile, 4 million people show signs of soil-transmitted helminths, 41,400 to 169,000 have cysticercosis, and around 8000 have schistosomiasis. A study in Chicago found that about 12% of recent immigrants tested had signs of present or previous infection with dangerous parasites. The most common infections were Toxocara (6.4%), followed by S. stercoralis (4%). Infection rates were similar in men (7%) and women (8%).

On a global level, the prevalence of these infections has significantly fallen since 1990. For instance, ascariasis has reduced from 1089.36 million cases in 1990 to 799.68 million cases in 2016. Similar reductions are seen with trichuriasis, hookworm, schistosomiasis, lymphatic filariasis, and onchocerciasis. However, more than 2 billion people worldwide still have soil-transmitted helminthiasis.

• In the USA, 1.3 to 2.8 million people show signs of Toxocara infection.
• 4 million people have soil-transmitted helminths.
• 41,400 to 169,000 people have cysticercosis.
• About 8000 people have schistosomiasis.
• In a Chicago study, 12% of recent immigrants showed signs of a parasitic infection.
• Most common infections among the studied immigrants were Toxocara (6.4%) and S. stercoralis (4%).
• Infection rates among men and women were almost similar, with 8% of women and 7% of men affected.
• Globally, the prevalence of these infections has significantly dropped since 1990, but over 2 billion people still have soil-transmitted helminthiasis.

Signs and Symptoms of Helminthiasis

Helminthiasis, or parasitic worm infection, mainly affects individuals from developing countries, particularly those in rural areas with poor sanitation and hygiene. The condition is most prevalent among preschool and school-aged children. The symptoms of helminthiasis depend on the severity of the infection, with symptoms ranging from mild to severe, the latter often associated with a high number of worms in the body.

Patients with adult ascariasis, a type of helminthiasis, may experience a variety of symptoms. These may include:

• Bleeding in the upper digestive tract
• Inflammation of the gallbladder or pancreas
• Abdominal pain and sensitivity
• Anemia, fever, and jaundice
• Vomiting (sometimes of long cylindrical worms)
• Appetite loss and weight loss
• Weakness and altered bowel habits
• Abdominal swelling and increased bowel sounds

A. duodenale and N. americanus infections, other types of helminthiasis, are often asymptomatic but can sometimes cause skin lesions, pneumonia, abdominal pain, and variety of other symptoms if the worms migrate in the body.

Infections with S. stercoralis, also a type of helminth, can lead to serious symptoms and complications if not properly treated. Infections can sometimes remain silent, but severe cases can induce rapid weight loss, lack of appetite, and significant damage to organs including the diseases of the meningitis, kidney failure, and shock.

Infections from T. trichiura, another type of worm, are often asymptomatic. Nevertheless, severe infections may lead to symptoms like weakness, abdominal pain, and cognitive impairment, particularly in children.

Schistosomiasis, a disease caused by a type of parasitic worms, can be either acute or chronic. Symptoms may include fever, fatigue, rash, abdominal pain, and enlargement of the liver and spleen. Chronic schistosomiasis can cause long-term damage to various organs including the bladder and lungs.

Elephantiasis, primarily caused by the worm Wuchereria bancrofti, can result in various symptoms such as fever, swelling of the limbs, and severe pain, particularly in the genital area. Echinococcosis, taeniasis and Diphyllobothriasis, caused by different types of worms, can also have a variety of symptoms or remain asymptomatic until complications arise.

Testing for Helminthiasis

Ascaris lumbricoides, a type of parasitic worm, can be diagnosed by finding its eggs, larvae, or adult worms. Various tests and procedures like chest X-rays, bronchoscopy (a procedure that allows your doctor to look at your airway through a thin viewing instrument), or analyzing samples from your lungs or stomach might be used. These tests are especially useful for a condition called Loeffler syndrome, which is commonly caused by this parasitic infection.

In these infections, the presence of certain blood cells (eosinophils) and a specific type of protein (IgE) can indicate an acute larval infection.

To simplify the diagnostic process and make it accessible even in remote areas, various techniques have been developed. The Kato-Katz technique is a simple and field-friendly test that is used mainly for public health control. Techniques like McMaster, FLOTAC, and mini-FLOTAC concentrate on finding the eggs and can be more sensitive.

Ultrasonography is a diagnostic tool used for ascaris infections of the pancreas and liver. However, duodenoscopy (a procedure that checks the health of your pancreas and gallbladder) and endoscopic retrograde cholangiopancreatography (a procedure to diagnose and treat problems in your liver, gallbladder, bile ducts, and pancreas) can also be used.

Stool microscopy, a test that examines stool under a microscope, is enough for uncomplicated cases. However, for severe instances, a colonoscopy or even a biopsy might be needed. An evaluation of iron-deficiency anemia is also essential in certain syndromes associated with this infection.

On the other hand, Loeffler syndrome can also occur due to A. duodenale and N. americanus infections, and the diagnosis is the same as that for Ascaris infection. Stool microscopy is usually used for diagnosing intestinal infections. Capsule endoscopy might be used to identify the worms, although this technique is rarely used. Anemia evaluation is essential in hookworm infections.

S. stercoralis infection can also lead to Loeffler syndrome, and the diagnosis method is the same as Ascaris-induced Loeffler syndrome. Duodenoscopy with duodenal biopsies is useful for diagnosing most cases. Some other diagnostic tests will be used depending on the extent of gut damage. Tissue from lung, bronchial, and small bowel biopsies might be necessary if Strongyloides overgrowth syndrome is suspected.

Schistosomiasis is typically diagnosed by microscopic examination of ova in urine or stool. The Kato-Katz technique might be used to estimate the infection’s severity. This condition can also be identified by the presence of eggs in tissue biopsy specimens.
Ultrasonography may be necessary for hepatosplenic schistosomiasis, a specific form of this condition.

Diagnosing lymphatic filariasis usually starts with assessing the patient’s exposure history in endemic areas, followed by blood tests. In some cases, a skin biopsy might be needed.

The hydatid cyst is another parasitic infection that is usually diagnosed through a series of lab tests and imaging techniques like ultrasonography, CT scans, and MRI.

For intestinal taeniasis and neurocysticercosis, antibody-based tests and antigen-detection tests may be used along with neuroimaging tests.

Finally, diphyllobothriasis can be assessed by analyzing the patient’s symptoms, lab results, and the presence of eggs or proglottids in the stool sample.

In general, diagnosing parasitic infections requires a combination of medical history review, clinical examination, laboratory tests, and imaging techniques. Treatment would then depend on the type of infection, its severity, and the patient’s overall health status.

Treatment Options for Helminthiasis

Keeping clean is one of the best ways to avoid getting a helminth infection, also known as a worm infection. Doctors have several medications they can use if you’re infected with A. lumbricoides, a type of worm. These may include albendazole, mebendazole, pyrantel pamoate, levamisole, and ivermectin. If the infection becomes severe and blocks your intestines, you’ll need special treatments, including IV support, antiparasitic drugs, and antibiotics. In some cases, surgery may be necessary to deal with complications like small bowel obstruction, intussusception (where one part of the intestine slides into another part), and volvulus (twisting of the intestines).

If the worms have infected your liver or bile ducts and medications aren’t working, then doctors might need to consider endoscopic (using a special tube with a light to see inside your body) or surgical therapy.

For another type of worm called trichuriasis, the same medications used for A. lumbricoides can be used. If the infection is severe or causes anemia (low iron levels in your blood), you may be given iron supplements. Additional therapies can help if you develop dysentery, a condition that causes severe diarrhea.

For A. duodenale and N. americanus infections, which are other types of worms, the treatment includes albendazole or mebendazole. Iron supplementation can help provide extra nutrition.

In a condition called Strongyloides hyperinfection syndrome or when the strongyloides worm spreads throughout the body, doctors can use medicines known as benzimidazoles. Hydration, nutrition support, and antibiotics are given as needed; the medication, ivermectin, should be provided until the stool or spit test shows no indication of the parasite for two consecutive weeks.

For schistosomiasis, a worm infection that can affect various organs in the body, the first choice for treatment is a drug called praziquantel. If symptoms are severe or if you develop Katayama fever (an allergic reaction to the worm eggs), doctors may need to repeat the treatment. Steroids (prescription anti-inflammatory drugs) can also help reduce fever symptoms.

Lymphatic filariasis (a worm infection that can affect the lymph system and cause swelling in the body) can be managed with medications such as ivermectin, suramin, mebendazole, flubendazole, and diethylcarbamazine. Other optional therapies include surgical treatment, thermal (heat) therapy, and herbal remedies.

For a condition called cystic echinococcosis (caused by tapeworm larvae), doctors use several methods, including medication, specially directed non-surgical treatment using a needle, careful observation without immediate treatment, or surgery. Benzimidazoles are the main medication used in these situations.

The treatment options for neurocysticercosis (an infection of the brain or muscles by tapeworm larvae) include symptom management with medicines like anticonvulsants (for seizures) and pain relievers. Doctors might also treat with antiparasitic medications and, in some cases, surgical removal of the worm or inserting a drainage device (shunt). For another worm infection, called diphyllobothriasis, doctors usually use a drug called praziquantel. Niclosamide can be another treatment option.

What else can Helminthiasis be?

Here are some health conditions which might require medical attention:

• Nutritional deficiencies
• Anemia
• Asthma
• Cholecystitis (gallbladder inflammation)
• Crohn’s disease (a type of inflammatory bowel disease)
• Lymphedema (swelling in the arms or legs)
• Lymphogranuloma Venerum (a type of sexually transmitted infection)
• Tuberculosis
• Loffler syndrome (a lung condition)
• Chronic obstructive pulmonary disease (a lung disease)
• Inflammatory bowel diseases
• Acute bacterial gastroenteritis (stomach flu)
• Amoebiasis (intestinal infection)
• Giardiasis (a type of intestinal infection)
• Acute pancreatitis (inflammation of the pancreas)
• Biliary colic (gallstones)
• Intestinal volvulus (twisting of the intestine)
• Intussusception (a condition where the intestine slides into another part of the intestine)
• Encephalitis (inflammation of the brain)
• Meningitis (infection of the lining of the brain and spinal cord)
• Idiopathic epilepsy (seizures with no known cause)
• Biliary obstruction (blockage in the bile ducts)
• Biliary cirrhosis (scarring of the bile ducts in the liver)
• Portal hypertension (high blood pressure in the liver)
• Liver abscess (a pus-filled mass inside the liver)
• Lung abscess (a pus-filled mass inside the lungs)
• Hepatic cyst (fluid-filled pocket in the liver)
• Hypothyroidism (underactive thyroid)
• Pernicious anemia (a decrease in red blood cells when the body can’t absorb enough vitamin B12)
• Folic acid deficiency

What to expect with Helminthiasis

The future health outcome or prognosis of a helminthiasis, which is a disease caused by parasitic worms, heavily relies on how severe the worm infection is. If there are a lot of worms, diseases like ascariasis can lead to severe complications, such as a blockage in the intestine. Strongyloidiasis, a type of parasitic infection, typically has a good prognosis, although there are severe forms of this infection that can lead to a high death rate.

Infections caused by A. duodenale and N. americanus have an excellent prognosis. With the right medication to kill the worms and iron and diet therapy, complete cure is possible in most cases. The future health outcome for echinococcosis, a parasitic infection caused by tapeworms, mainly depends on the type of infestation.

Cystic echinococcosis usually has a positive prognosis and can be completely cured if the cyst can be entirely removed through surgery without causing any spillage. Alveolar echinococcosis has a worse prognosis than cystic echinococcosis, although detecting it early and completely removing it through surgery can cure the disease.

Diphyllobothriasis, an infection caused by tapeworms found in fish, has an excellent prognosis. Filarial diseases, which are infections caused by parasites that are spread by blood-feeding insects, are rarely fatal and generally have a good prognosis.

In the case of schistosomiasis, a disease caused by parasitic worms living in fresh water, the prognosis is usually good if the patient has hepatosplenic schistosomiasis because their liver function is preserved.

However, treatment may not be beneficial for patients suffering from late-stage complications of portal hypertension, severe pulmonary hypertension, or cor pulmonale, which are diseases that affect the liver, lungs, and the heart, respectively. Like other parasitic diseases, the prognosis of schistosomiasis largely depends on how many worms are present in the body.

For taeniasis, which is an infection caused by a species of tapeworm, the prognosis is excellent when treated with medication that kills the worms. However, the location of the cysts can impact this prognosis.

Possible Complications When Diagnosed with Helminthiasis

Helminth infections, or infections caused by parasites, can result in a variety of health complications. These may include:

• Anemia, a condition where your body lacks enough healthy red blood cells to carry oxygen to your tissues
• Malnutrition, which means your body is not getting enough nutrients
• Growth and developmental retardation, which means slowed or stunted physical growth and mental development
• Intestinal obstruction, a complete or partial blockage of the bowel that prevents solids and fluids from passing through
• Gastrointestinal hemorrhage, which is bleeding in your gastrointestinal tract
• Cor pulmonale, a condition that causes the right side of your heart to fail
• Portal hypertension, high blood pressure in the portal vein that delivers blood from the intestines to the liver
• Urinary bladder carcinoma, or bladder cancer
• Neurological complications such as seizures and spinal cord diseases
• Primary and secondary infertility, or the inability to conceive a child
• Ectopic and tubal pregnancies, where the fetus develops outside the womb
• Hypogonadism, a failure of the gonads to function properly
• Systemic cysticercosis, a parasitic infection that can affect the brain, muscles, and other tissues
• Cholangitis and cholecystitis, inflammation of the bile ducts and gallbladder respectively
• Pancreatitis, inflammation of the pancreas
• Cyst or Hydatid cyst rupture, the breaking open or bursting of cysts caused by parasites
• Chronic lymphatic damage, or long-term damage to the part of your immune system that helps fight infections
• Blindness

Preventing Helminthiasis

Good personal hygiene is advised, including washing hands, cleaning fruits and vegetables, using toilets properly, and not eating dirt. Walking barefoot outdoors is generally not a good idea. Education about good hygiene and better sanitation facilities could lower the chances of getting infected. If you travel, it’s best to avoid touching fresh water in places where infections are common. Many infections don’t show any symptoms, so people returning from such places should get a blood test for a type of infection called schistosomiasis.

If the blood test shows signs of infection, further tests should be done on urine and stool to identify the type of parasite. In the case of a taeniasis infection (a type of worm infection), it’s important to dispose of human and pig waste properly to prevent contaminating water sources. Cleaning, washing, and properly cooking raw vegetables and water-grown food, as well as properly cooking beef, pork, and fish, can help prevent infection with intestinal flukes (a type of worm infection).

Along with these measures, it’s important for patients to take care of their pets, especially dogs, and avoid contact with stray dogs to prevent a type of infection called echinococcosis. Educating people about proper pet care and avoidance of stray dogs could help in preventing such infections.