Hookworms are parasitic worms, primarily Ancylostoma duodenale and Necator americanus, that reside in the intestines and feed on blood. These infections can lead to health complications, including iron-deficiency anemia and protein deficiency. Globally, hookworm infections affect an estimated 406 to 480 million individuals. Identifying and addressing these infections is important for preventing long-term health issues, particularly in children where development can be affected.
Recognizing the Need for Testing
Many individuals with hookworm infections may not experience symptoms, especially if the infection is light. When symptoms do occur, they can include a skin rash (“ground itch”) at the site of larval penetration, fever, coughing, abdominal pain, diarrhea, and loss of appetite. Persistent blood loss can lead to iron-deficiency anemia, characterized by fatigue and weakness.
Factors increasing hookworm infection risk include living in warm, moist climates with inadequate sanitation, where larvae thrive. Walking barefoot on contaminated soil is a common entry point. Children playing in contaminated soil and individuals in occupations with direct soil contact, like farming, are also at increased risk. Testing may also be considered for those who have traveled to regions where hookworm is common, even without symptoms.
Primary Diagnostic Methods
The most common diagnostic approach involves examining stool samples for hookworm eggs. This microscopic examination, often part of an Ova and Parasite (O&P) test, identifies characteristic eggs. The Kato-Katz technique is a specific stool examination for intestinal helminths, including hookworms. It involves preparing sieved stool on a slide, cleared with glycerol for better egg visibility. While widely used, its sensitivity can be low in light infections, and eggs can disappear quickly if not read within 30-60 minutes.
Molecular tests, such as Polymerase Chain Reaction (PCR), offer a more sensitive detection method. PCR identifies the parasite’s genetic material in stool samples, providing a direct diagnosis. These tests can detect infections even with low egg counts and differentiate between hookworm species. Though highly sensitive, PCR methods are not as widely available or routinely used as microscopic examinations.
Blood tests can suggest a hookworm infection, though they do not directly diagnose the worms. A complete blood count (CBC) may show elevated eosinophils (eosinophilia), which can appear weeks before eggs in stool, especially during the parasite’s migratory phase. Blood tests also detect iron-deficiency anemia, a common consequence of hookworms feeding on blood. Anemia indicators include low hemoglobin and microcytic hypochromic red blood cells.
Sample Collection and Preparation
Proper stool sample collection is important for accurate testing. Collect a fresh sample in a clean, dry container, ensuring it is not mixed with urine or toilet water. Transfer the sample into vials containing a preservative (e.g., formalin, PVA) to maintain egg or parasite integrity. Collect small portions from different areas, especially any bloody or mucous parts.
For optimal results, process stool samples within two hours or immediately place them in preservative. Healthcare providers often recommend collecting multiple samples, typically three over five to seven days, because hookworm eggs are shed intermittently, increasing detection chances. Patients should inform their provider about recent medications (e.g., antacids, barium, mineral oil, antibiotics) that can interfere with results and may require a delay. All collected samples must be clearly labeled with the patient’s name, date, and time.
Blood samples, when needed, are typically collected by a healthcare professional, usually by drawing venous blood from an arm. Capillary blood samples can also be used for certain smears. While specific timing is important for some parasitic infections, blood tests for hookworm indicators like eosinophilia or anemia are generally performed before treatment.
Understanding Your Test Results
A positive test result means hookworm eggs or genetic material were identified in the sample, confirming infection. A positive result implies addressing the parasitic burden, as hookworms feed on blood and can lead to significant blood loss. Untreated infections can result in iron-deficiency anemia and protein deficiency, affecting overall health and, in children, growth and development.
Conversely, a negative test result does not always rule out infection. Hookworm eggs can be shed intermittently, and some diagnostic methods have lower sensitivity, especially for light infections. If symptoms persist despite a negative result, a healthcare provider may recommend further testing. Regardless of the initial outcome, discuss results with a healthcare provider. They can explain findings, consider the clinical picture, and recommend next steps, such as medication or iron supplements for anemia.