CONDITIONS & ALLERGIES
Parasites
GUT HEALTH
Gastro - Intestinal Parasites
These tests comprise of screens for intestinal parasites like worms and single-celled organisms such as Blastocystis hominis, amoeba, liver fluke etc.
What are Gastro-Intestinal Parasites?
Parasites are a truly diverse group of pathogens from microscopic size to large worms which can be seen with the unaided eye. Many have different life stages, which are sometimes outside the gut and/or are intermittently released. Therefore, detection can be difficult. A first indication of parasitosis is a pronounced blood eosinophilia or increased EPX values in the stool, for which allergies can be ruled out as the cause.
If there are still unclear intestinal or general symptoms, the possibility of a parasitosis should always be considered and analysed in the laboratory. Relevance and epidemiological data depending on the parasite and the stage of its development, the broad clinical spectrum of parasitosis can include the following optional symptoms: skin eruptions, nonproductive cough, fever, nausea, vomiting, abdominal pain, weight loss and fatigue due to malabsorption syndrome, constipation, changing stools, and acute or chronic watery, bloody, or mucous diarrhoea, hunger attacks which alternate with times of no appetite, anaemia, anal itching, symptoms following foreign travel.
The most widespread human intestinal parasites include the mostly harmless child pinworm (Oxyuris/Enterobius vermicularis) and the roundworm (Ascaris lumbricoides). As already mentioned, travellers returning from a trip in areas with less hygiene standards represent an important risk group for parasitosis. Other risk groups include people with close contact to pets or livestock, sewage contaminated water or immunodeficient patients (AIDS patients, tumour patients after chemotherapy). Children are affected by parasites more frequently than adults because their immune systems are not yet fully developed, and they are still not as aware of hygiene.
Diagnostic Methods
The detection of intestinal parasites is carried out via several detection methods for our parasite tests. The visual observation of the stool for large worms and worm parts in the sample, followed by microscopy for identification. Therefore, for the best possible outcome to detect large parasites it is important to observe your stool and if you see moving structures to include them into the sample. If you have ordered the kit, because you have seen such moving structures on a previous occasion, it is better to wait till you see them again and include them into your sample. Please note that the stool also contains undigested fibres, stringy mucus or shed gut mucosa which look very worm like, but fortunately the lab will be able to tell the difference!
As the next step SAF concentration method is used to concentrate and isolate smaller parasites such as protozoa cysts, worm eggs, and -larvae from stool. The so called enriched sample are analysed by light microscopic for parasitic detection. A prerequisite for successful parasite detection from stool is that sufficient reproductive stages, e.g. eggs or proglottids, are excreted with the stool. The number of eggs laid can vary greatly, depending on the type of parasite and the number of animals with which one is infected.
The microscopic-parasitic stool examination covers the widest range of parasites and is therefore recommended as a cost-effective screening method. However, since this is a manual method, despite enrichment and well-trained personnel, the same sensitivity cannot be achieved as with the fully automated immunological method or with the PCR method. This is particularly true for protozoa detection.
Microscopic detection of parasites from tape test specimens is recommended for the detection of Oxyuren (Pin worm) eggs. In the case of these worms, the eggs are laid extra intestinally on the skin around the anus, which is why the worm eggs can only rarely be found in the stool. The sticky eggs can be collected and then examined under a light microscope by means of a contact preparation using transparent adhesive strips (not cloudy ones!), transfer on a glass slide. This analysis is recommended for anal itching and/or suspected parasitosis with multiple negative stool results.
Additionally on each sample the Multiplex real-time PCR (polymerase chain reaction) method is carried out. The polymerase chain reaction (PCR) is a very sensitive procedure in which the amplification of DNA fragments allows specific detection of a parasite using the smallest amounts of its genetic material in a sample. Compared to previous immunological or microscopic parasite detection methods, this method offers numerous advantages: It compensates for the high false-negative rate of microscopic detection, as even the smallest amounts of parasites-specific DNA can be detected. It is well suited for detecting sensitive parasites whose morphological structures could previously only be identified from stool samples that were a few hours old or that were fixed immediately (e.g. Dientamoeba fragilis). It enables the therapy-decisive differentiation between pathogenic and closely related non-pathogenic species such as Entamoeba histolytica versus Entamoeba dispar. The multiplex real-time PCR used by BTS-Ireland enables the simultaneous detection of different parasites from a sample in one analysis run by using different, color-coded probes. In addition to the higher sensitivity and specificity compared to microscopy and immunology, this innovative screening method offers a significant price advantage compared to standard PCR analyses. The Protozoa G. lamblia, E. histolytica, Cryptosporidium, B. hominis, D. fragilis are detected by this method.
Diagnostic Methods (cont.)
Limitation of the test: Some parasites do not lay eggs in the intestine and are therefore not excreted in the stool, e.g. in the case of Oxyuren. Other parasites have other life stage outside the intestines, during those time of their lifecycle they cannot be detected in the stool. If clinical suspicion persists, despite negative results, then regardless of the method chosen, a pre-patent period should be considered if it has not yet elapsed, and the analysis repeated once it has elapsed.
Definitions
Pre-patent: Time period until eggs or other reproductive stages can be detected in the stool for the first time, after infection e.g. time period from infection with eggs or larvae to development into a sexually mature worm and first egg shedding.
Patency: Duration of excretion of the reproductive stages/duration of detectability often corresponds to the life expectancy of an adult animal, but can also go far beyond this in the case of auto-infections.
Profiles of the most important intestinal parasites
Relevant parasites of the intestine and the intestinal appendages can be divided into two large groups: protozoa (single-celled organisms) and helminths (worms). Human parasitic worms essentially belong to the class of Nematoda, Trematoda or Cestoda. There are around 1 million different nematode species, of which 15% are animal and 10% plant parasites. A worm infection of the intestine and some of the intestinal appendages can be detected by examining the stool using a light microscope. It is also possible to send in worm parts (proglottids) or whole worms in saline solution.
The most important human pathogenic protozoa belong to the order of flagellates (e.g., Giardia lamblia), amoebas (e.g., Entamoeba histolytica, Blastocystis hominis) and sporozoa/coccidia (e.g. Cryptosporidium parvum). They can be detected both by light microscopy and by means of PCR from stool samples.
Profiles of the most important intestinal parasites
Blastocystis hominis
Blastocystis is a genus of single-celled protozoan parasites comprises of several species, living in the gastrointestinal tracts of species as diverse as humans, farm animals, birds, rodents, reptiles, amphibians, fish, and cockroaches. These have a widespread geographic distribution often associated with those who work with animals. An important transmission route is the consumption of contaminated food or drinking water. Infection prophylaxis: Avoid contact with animal and human faeces. Good hand, toilet and kitchen hygiene should be ensured. Clinic: Blastocystis colonization’s can be asymptomatic and thus remain unrecognized. The protozoa is considered a facultative pathogen, because it is often only of clinical importance in immunocompromised patients or in severe infestation. The incubation period in animals is 2 to 3 days, in humans it is not known exactly. The majority of manifest diseases appear as abdominal pain with mushy or watery diarrhoea, weight loss and flatulence. In addition, Blastocystis infections are increasingly being detected in patients with irritable bowel syndrome and inflammatory bowel diseases. Prepatent period (time between infection till symptoms manifest): 2 days to 3 weeks Patency: 2 to 3 weeks. Therapy is only recommended if there are associated symptoms and after all other possible causes – infectious or non-infectious (maldigestion, food intolerance) – have been ruled out.
Cryptosporidium
Is a waterborne parasitic, which cause infection from contaminated drinking water or swimming pools, lakes and rivers. Diseases caused by cryptosporidium occur worldwide and at all ages, especially in people with a weak immune system. The transmission takes place faecal-orally through contact with diseased animals (zoonosis) or infected people. The microvilli of the intestinal epithelium are increasingly destroyed by sexual and asexual reproduction of the obligate intracellular pathogens. Newly formed, infectious oocysts are excreted in the stool and, after ingestion, can invade the intestines of a new host. Infection prophylaxis: Since the small, light oocysts can also be spread airborne by being stirred up, immunocompromised patients in particular should avoid direct contact with animal and human faeces. Good hand, toilet and kitchen hygiene should be ensured. Drinking water should be boiled or sterile filtered (1 µm pore size). Food should only be consumed after thorough washing with drinking water or cooked. Avoid swallowing fresh water when bathing/swimming. Clinic: Cryptosporidium infections can have relatively few symptoms. However, brief, pronounced watery diarrhoea (particularly in immunocompromised patients) with or without a persistent cough in humans is the most common symptom presentation. Further it can be accompanied by a slight fever, nausea, vomiting and cramping abdominal pains. That occurs after an incubation period of 1 to 2 days. Subtotal atrophy of the villi of the small intestine can lead to a pronounced malabsorption syndrome. Prepatent time: 3 (up to 30) days Patency: 12 to 14 days.
Human cryptosporidiosis is a notifiable disease in Ireland. We will notify your Medical Officers of Health in your HSE Health Region about your positive test results. The HSE medical officer will be in contact with you, to help identify possible infection sources and prevent the disease from spreading. In Ireland we must refer notifiable diseases to primary health care practitioners, before they may also be treated by their complimentary health care practitioner.
Entamoeba histolytica (amoeba)
E. histolytica belongs to the genus of Amoebozoa found as internal parasites or commensals of animals. In 90% of the case the infection is asymptomatic, but the pathogenic phenotype of Entamoeba histolytica is the pathogen responsible for amoebiasis. Their reservoirs are mostly healthy people colonized with amoebas, who excrete the very resistant amoeba cysts. Infection occurs faecal-orally through contaminated food (e.g. salads, fruit) and drinking water (ice-cold drinks). Insects (flies, cockroaches) and poor hygiene also contribute to the spread. Entamoeba histolytica is able to form both infectious cysts and vegetative stages, which can penetrate tissue (e.g. the intestinal wall). Infection prophylaxis: Good hand, toilet and kitchen hygiene should be ensured. In endemic areas, fresh water should be boiled or sterile filtered (1 µm pore size) before drinking. Chlorination is mostly ineffective against cysts and therefore not suitable. Food should only be consumed after thorough washing with drinking water or cooked. Avoid swallowing fresh water when bathing/swimming.
Clinical features: A few days or several months after infection, children and immunocompromised people in particular may experience bloody, mucous, raspberry jelly-like diarrhoea with subsequent dehydration and a shift in electrolytes. In about 25% of cases, the infection takes an atypical course with constipation, abdominal pain, nausea and exhaustion. In addition to local tissue damage in the intestinal wall (ulcerations, necrosis), the parasites can also infect other organs, mainly the liver, through haematogenous spread. The most common complication is liver abscess, which is accompanied by high fever, weakness and pain in the upper right abdomen. Prepatent period: 2 to 7 days Patency: possibly years.
Giardia lamblia (Lamblia)
Giardia lamblia (synonymous with Lamblia intestinalis and Giardia duodenalis) is a flagellated protozoan parasite that is distributed worldwide, but is particularly prevalent in warm, southern regions. It colonises and reproduces in the small intestine, causing giardiasis. The cysts are transmitted faecal-orally through contaminated drinking water, unclean food (poor hand hygiene, flies, cockroaches) or directly through smear infections after contact with infected people or animals (dogs). Mainly children are affected by the disease. Infection prophylaxis: Good hand, toilet and kitchen hygiene should be ensured. In tropical areas, fresh water should be boiled or sterile filtered (1 µm pore size) before drinking. Chlorination is ineffective against cysts and therefore not suitable. Food should only be consumed after thorough washing with drinking water or cooked. Avoid swallowing fresh water when bathing/swimming. Clinic: Most lamblia infections progress without symptoms and thus remain unnoticed, but asymptomatic patients can still excrete live cysts and infect other people. The acute stage of the disease is accompanied by severe, sometimes watery-frothy, yellowish diarrhoea and occurs 3 to 25 days after infection. It is often accompanied by exhaustion, nausea and upper abdominal pain. As a rule, the diarrhoea stops after 1 to 2 weeks. However, chronic infections parasite attaches to the epithelium. Giardiasis does not disseminate haematogenously, nor does it spread to other parts of the gastro-intestinal tract but remains confined to the lumen of the small intestine. Giardia trophozoites absorb their nutrients from the lumen of the small intestine and are anaerobes. Colonisation of the gut results in inflammation and villous atrophy, reducing the gut's absorptive capability and leading to malassimilation. In rare cases, infections of the stomach, bile ducts, reactive arthritis or urticaria can occur. Lactose intolerance after parasite eradication is possible. Prepatent period: 3 to 4 weeks Patency: possibly years.
Therapy: If diarrhoea is present, therapy should be initiated. Co-treatment of asymptomatic carriers is generally recommended since malabsorption can subsequently occur here as well.
A re-test 3-4 weeks after the completion of the program is highly recommended as therapy control. Patients can avail of a 5 % discount for the re-test.
Giardia lamblia is a notifiable disease in Ireland. We will notify your Medical Officers of Health in your HSE Health Region about your positive test results. The HSE medical officer will be in contact with you, to help identify possible infection sources and prevent the disease from spreading. In Ireland we must refer notifiable diseases to primary health care practitioners before they may also be treated by their complimentary health care practitioner.
Cyclospora
The sporozoa Cyclospora cayetanensis is distributed worldwide. The only known host is humans. After the cysts have been excreted with the stool, infectious stages only mature within 5 to 12 days, which is why direct transmission from person to person is unlikely. Infection usually occurs through oral ingestion of oocysts from contaminated food or drinking water. Infection prophylaxis: Good hand, toilet and kitchen hygiene should be ensured. Drinking water should be boiled or sterile filtered (1 µm pore size). Food should only be consumed after thorough washing with drinking water or cooked. Avoid swallowing fresh water when bathing/swimming. Clinic: After 2 to 7 days, intermittent, watery diarrhoea occurs (3 to 4 times a day), which can last up to 9 weeks or can take a chronic course in immunocompromised patients (E.g., AIDS). Due to the destruction of intestinal epithelium and the loss of water and electrolytes, upper abdominal pain and exhaustion can also occur as additional symptoms.
Ascaris lumbricoides (roundworm)
Ascaris lumbricoides is found worldwide, but is most prevalent in warm, humid climates with poor sanitation standards. Infection with roundworm eggs occurs through consumption of contaminated vegetables (salad or raw vegetables). The larvae hatch in the small intestine, pass through the intestinal wall, reach the liver via the portal circulation and from there finally the heart and lungs. From the lungs, they migrate to the pharynx and are swallowed back into the intestine. In the jejunum, they finally develop into sexually mature worms, whose females can lay up to 200,000 eggs per day. Clinic: 85% of infections are asymptomatic. In the case of a severe infestation, symptoms such as fever, shortness of breath and coughing with bloody sputum can already occur during the passage through the lungs (after approx. 7 days). In this phase of the infection, an increase in blood eosinophils and a transient eosinophilic pulmonary infiltrate (Löffler syndrome) can be seen in the X-ray image. The infection of the intestine can manifest itself in nausea, abdominal pain or other non-specific abdominal symptoms. Children are most commonly affected, and in this age group the infection may also cause poor weight gain, malnutrition, and learning problems. Complications such as ileus and, in rare cases, obstructive jaundice, liver necrosis, or peritonitis can occur. Infection prophylaxis: Food should only be eaten after it has been thoroughly washed or cooked. Prepatent period: 8 weeks, Lifetime of the adult worms: 9 to 15 months with auto infection longer
Dientamoeba fragilis
D. fragilis is a protozoa parasite which occurs worldwide and is the most common human pathological Parasite from the class Trichomonas. D. fragilis lives in the gastrointestinal tract of human, primates, pigs and rodents. Outside the gut the trophozoites are not very stable and therefore making detection by Microscopy difficult. In addition to transmission via helminth eggs as vectors (mainly Enterobious vermicularis), faecal-oral transmission of environmentally resistant cysts and pre-cysts from person-to-person or via contaminated food and water is assumed. Infection prophylaxis: Avoid contact with animal and human faeces. Good hand, toilet and kitchen hygiene should be ensured. Infections are often asymptomatic, but may cause acute or chronic intermittent diarrhoea, abdominal pain and fatigue. The most common symptoms are nausea, malaise, weight loss or failure to increase weight, appetite loss. In half of the cases an eosinophilia is present. Without treatment a third of the infections turn chronic. Research studies have shown that these protozoa can be associated with the development of Colitis, IBD and IBS. Incubation time is days to weeks.
Enterobius vermicularis / Oxyuris vermicularis (child pinworm)
The pinworm (Enterobius vermicularis / Oxyuris vermicularis), also known as threadworm or seat worm, is a common human intestinal parasite. Small children and school children are particularly affected. Infection can occur through ingestion of the eggs or inhalation (shaking the bed). The transmission path is direct from person to person, via autoinfection or contact infection with contaminated objects. After ingesting the eggs, the larvae hatch in the gut and develop into sexually mature worms within 1 month. To lay eggs, the females crawl out of the anus at night and lay their eggs on the skin around the anus. The sticky eggs get on the fingers and under the nails through scratching and can stick to other utensils through contact. Infection prophylaxis: Hygiene measures such as careful washing of bed linen and under garments and general good hand, toilette and kitchen hygiene should be implemented.
Clinical features: The infection is usually harmless and characterized by the main symptom anal itching. Severe itching at night can lead to sleep disorders, which can lead to growth and development disorders in children. Infections of the female genital organs are also possible. Severe infestation can result in intestinal inflammation, appendicitis or peritonitis.
Prepatent period: 1 month Patency: life expectancy of a female about 2 months; eggs are viable for up to two weeks, therefore, to prevent reinfection a second treatment round after two weeks is recommended. Pinworms are usually considered a nuisance rather than a serious disease.
Treatment is straightforward in uncomplicated cases, however, elimination of the parasite from a family group or institution (creche, preschool) often poses significant problems — either due to an incomplete cure or re-infection. The species solely affecting humans, Enterobius vermicularis, has a worldwide distribution, and is one of the most common parasitic worm infections in the developed world. Pinworm infection has no association with any socioeconomic level, race, or culture.
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