Parasitology

Parasites cause chronic inflammation and interfere with the host's metabolism. In cases of disrupted gut microbiota and compromised barrier resistance, parasites can develop a strong pathological potential.

Parasitological examination originally took place by microscopic stool examination for cysts, the encapsulated parasite. As cysts, parasites can survive outside the body for longer periods, for example, in soil.

However, there are parasites that do not form cysts. These parasites are very sensitive to oxygen and will quickly disappear after the faecal sample is collected.

Therefore, the TFT was developed, in which parasites are fixed and can then be detected via microscopic examination. This examination also includes immunological testing for antibodies of several common parasites.

Since 2010, a new, fast, and cheaper method has been available for the detection of parasitic infections, the qPCR method, which is a DNA-based examination for parasites. Polymerase Chain Reaction (PCR) is a rapid and highly sensitive method to multiply one or more specific parts from small amounts of genetic material, which can then be analysed. The sensitivity of PCR is higher than the sensitivity of traditional cyst/worm egg examination and the TFT. However, worm eggs are not detected by PCR. Sporadically occurring parasites such as Cyclospora and Isospora belli or apathogenic species such as Entamoeba coli, Endolimax nana, or Iodamoeba butschlii are also not found using PCR. The PCR method is therefore highly sensitive, but unfortunately extremely low in specificity. This means that the results of the PCR method are very reliable, but only a very limited number of parasites are tested. Therefore, RP Sanitas Humanus works with the high-quality parasitological Triple Feces Test (TFT).

The excretion of parasites is irregular. Therefore, for this test, faecal samples are collected over three days. Another characteristic of this test is that on days 1 and 3, sodium acetate acetic acid formalin (SAF) is used as a fixative. This ensures that the parasites are preserved, so they do not disintegrate and can thus be properly detected. The preparations are then stained according to the Iron Haematoxylin Kinyoun method (IHK method), a very good staining method. On day 2, specifically, the internal structure (nuclei, vacuoles) of possible parasites is examined using a direct Iodine-Potassium-Iodide (IKI) staining method. The aforementioned characteristics of the TFT are responsible for a much higher specificity and sensitivity regarding parasites in feces than with the conventional method, which involves sedimentation of fresh feces with ether. Each sample is microscopically examined for parasitological disturbances such as worms, worm eggs, and protozoa. In addition, an immunological examination of the samples is also performed for Entamoeba histolytica, Cryptosporidium, and Giardia lamblia.

The collection of the 3 stool samples does not have to be on 3 consecutive days, but can be taken at intervals of several days, provided they are 3 consecutive bowel movements. However, the 3 stool samples may not be collected on one and the same day.

It is therefore important that the parasitological examination is performed with the TFT, because, in addition to immunological, microscopic examination also takes place, allowing a much wider range of parasitic disturbances to be detected.