How to determine if one has a parasitic infection?

From the Guidelines

To determine if one has a parasitic infection, a healthcare provider should order diagnostic tests such as microscopy, serology, or PCR, depending on the suspected type of parasite, as outlined in the 2018 update by the Infectious Diseases Society of America and the American Society for Microbiology 1. When suspecting a parasitic infection, it is crucial to identify the specific type of parasite to guide appropriate treatment. The approach to diagnosis varies by disease, with some requiring microscopy and culture of bodily fluids or tissues, while others rely on serology or PCR 1.

Key Diagnostic Tests

• Microscopy of Giemsa-stained thick and thin blood films for malaria, babesiosis, and filariasis
• Serology for toxoplasmosis, toxocariasis, and trichinosis
• PCR for leishmaniasis, malaria, and other parasitic infections
• Examination of tissue biopsies or aspirates for cysticercosis, echinococcosis, and other tissue-dwelling parasites

Importance of Laboratory Expertise

The reliability of test results depends on the experience, resources, and expertise of the laboratory performing the tests 1. Large public health and reference laboratories are more likely to have the necessary expertise and volume of specimens to properly validate esoteric tests.

Prevention and Treatment

Preventing parasitic infections involves maintaining good hygiene, properly cooking food, and drinking clean water. Treatment depends on the type of parasite identified and may involve specific antiparasitic medications such as metronidazole, albendazole, mebendazole, and praziquantel, which should only be taken under medical supervision 1.

From the Research

Determining Parasitic Infection

To determine if one has a parasitic infection, several methods can be employed, including:

• Examination of stool, blood, or tissue specimens for the presence of parasites 2
• Use of specific diagnostic tests such as the "cellophane tape test" for pinworm infections 3
• Stool ova and parasite studies for diagnosis of Giardia and other intestinal parasites 3, 4
• Serologic assays, biopsy, barium studies, and liver imaging for diagnosis of Entamoeba histolytica and other parasitic infections 3
• Microscopy with direct fluorescent antibody testing for diagnosis of Giardia infection 4
• Microscopy with immunofluorescence for diagnosis of Cryptosporidium infection 4
• Polymerase chain reaction assays for diagnosis of Cyclospora infections 4
• Serum antibody testing for diagnosis of Trichinella infection 4

Considerations for Diagnosis

When diagnosing parasitic infections, it is essential to consider the following:

• The possibility of coexistence of infection with several parasites at the same time 5
• The frequency of parasites in the population and local epidemiological situation 5
• The importance of proper interpretation of laboratory test results, based on good knowledge of the biology of the parasite 5
• The potential for false-positive or false-negative results, and the need for tests with high sensitivity and specificity 5
• The use of various methods, including direct and indirect methods, to detect parasites 5
• The need for rapid and accurate diagnosis, particularly in endemic areas or in cases of severe symptoms 6

Diagnostic Methods

Various diagnostic methods are available, including:

• Microscopy, which remains the cornerstone of parasitological diagnostics, especially in field and low-resource settings 6
• Point-of-care tests, which allow for rapid and accurate diagnoses 6
• Molecular assays, which provide increased sensitivity in the identification of parasitic infections 6
• Lateral flow assays and immunochromatographic assays, which are rapid and easy to use 6
• Multiplex-PCR, which allows for the simultaneous detection of multiple parasites 6