Parasitic Infections: Meaning, Symptoms, Causes, and Diagnostic Tests

A parasitic infection occurs when a parasite enters the body and begins to live and multiply, causing illness or discomfort. While many parasitic infections are preventable through basic hygiene and daily practices, they can lead to health complications if left untreated.

This article provides an overview of parasitic infections’ meaning, their types, symptoms, and causes.

What is a Parasitic Infection?

Parasitic infections occur when parasites live and reproduce in the body. Parasites are living organisms that live on or inside another living being, called a host. They need this host for the nutrients that help them survive and grow.

Parasitic infections happen because of three main types of parasites:

• Protozoa (single-celled organisms): They are known to infect the blood, gut, brain, skin, and eyes.
• Helminths (parasitic worms): They are grouped into four categories: flukes, tapeworms, roundworms, and thorny-headed worms. They primarily settle in the intestinal tract, but can also reach the skin, brain, and other tissues at any stage of their development.
• Ectoparasites (such as ticks and lice): These parasites burrow into or attach to the skin but rarely spread to internal organs.

What are the Types of Parasitic Infections?

Parasitic infections are classified based on the kind of parasite involved and how they are transmitted:

• Zoonotic parasitic infections: These spread from animals to humans by contaminated food, water, or direct contact with infected animals or their waste. Some examples include toxoplasmosis (flu-like disease) and trichinellosis (a parasitic worm infection caused by raw meat consumption).
• Food- and water-borne infections: These occur when a person eats food or drinks water infected with parasites. Common examples include giardiasis (affects the digestive system) and cryptosporidiosis (a diarrheal disease).
• Bloodborne infections: They are transmitted through shared needles, blood transfusions, or organ transplants. Examples include malaria and Chagas disease (transmitted by a bug).
• Vector-borne infections: Such infections spread through insect bites, particularly mosquitoes, ticks, and flies, that carry parasites. Malaria and leishmaniasis (spread by sand flies) fall under this category.
• Human-to-human infections: These infections pass between people through close physical contact, sexual activity, or the faecal-oral route. Examples include trichomoniasis (sexually-transmitted) and scabies (a parasitic skin infection).

What Causes Parasitic Infections?

Various causes of parasitic infections include:

• Consuming contaminated food or water
• Contacting infected animals or their waste
• Eating undercooked meat
• Touching contaminated soil or surfaces
• Insect bites
• Having unsafe sexual intercourse

Additionally, people with weak immune systems, young children, and those with HIV/AIDS or cancer are more vulnerable to parasitic infections.

What are Parasitic Infection Symptoms?

Symptoms of parasitic infections depend on the type of parasite and the affected body part. Some infections produce noticeable symptoms shortly after exposure, while others may go undetected for a long time.

Common parasitic infection symptoms are:

• Diarrhoea, nausea, and vomiting
• Stomach pain and cramps
• Fever and fatigue
• Muscle aches and pains
• Skin rashes, redness, or sores
• Unexplained weight loss or increased appetite
• Swollen lymph nodes
• Neurological symptoms such as seizures or severe headaches

How are Parasitic Infections Diagnosed?

For detecting parasitic infections, common diagnostic methods include:

• Faecal exam: Stool samples are examined for parasites or their eggs.
• Absolute eosinophil count: A blood test that measures the number of eosinophils, a type of white blood cell that typically rises in response to a parasitic infection.
• Skin or tissue biopsy: A small sample of affected skin or tissue is examined under a microscope.
• Endoscopy or colonoscopy: A thin tube is inserted into the digestive tract to directly examine the intestines for parasites.
• Imaging tests: X-rays, MRI, or CT scans are used to detect lesions or organ damage caused by parasites.

How to Prevent and Manage Parasitic Infections?

Management usually involves parasitic infection treatments. Doctors generally recommend antiparasitic medications, antibiotics, and antifungals. Treatment depends on diagnosis and symptoms, and medications can only be taken after a doctor’s approval.

To prevent parasitic infections, one must:

• Wash hands regularly, especially before eating, after using the bathroom, and after handling animals.
• Drink only clean, treated, or bottled water, particularly when traveling.
• Avoid consuming undercooked or raw meat, fish, and unwashed fruits and vegetables.
• Practice safe sex to reduce the risk of sexually transmitted parasitic infections.
• Use insect repellent, wear protective clothing, and sleep under mosquito nets in high-risk areas.

Parasitic infections are manageable when detected early. If any symptoms are experienced, consult a healthcare provider promptly and book the necessary diagnostic tests, including an absolute eosinophil count, through the Dr Lal PathLabs app.

FAQs

1. Where do most parasites live in the human body?

Most parasites live in the intestinal tract, but they can also infect the blood, skin, brain, and lungs.

2. What are some symptoms of parasitic infections?

Common parasitic infection symptoms include abdominal pain, diarrhoea, fatigue, nausea, vomiting, itching, fever, and weakness.