Entamoeba Polecki - Research Paper Example

Entamoeba Polecki Introduction Entamoeba polecki is a parasite belonging to the Order Amoeba. Entamoeba polecki is one of the six species under the genus Entamoeba. The other five include- Entamoeba histolytica, Entamoeba dispar, Entamoeba moshkovskii, Entamoeba coli and Entamoeba hartmanni. All of these are parasites that reside in the lumen of the intestine of human hosts and cause and infections (Fotedar et al, 2007).E.polecki was first detected in two students from Kampuchea in Czechoslovakia in the year 1912 (Giboda, 1988). It is in fact a harmless and non pathogenic parasite and therefore causes no diseases in humans. Nevertheless the parasite causes infection and needs to be treated upon detection. One needs to adopt several prevention strategies to inhibit transmission of the parasite. Morphology of the Parasite Morphological difference is observed between the cysts and the trophozoites. Cysts are mostly uninuclear and measure up to 20 µm . The nuclei of the cysts ranged between 3.2-4.2 µm and it accounted for almost 29.5% of the cyst diameter. Abundant chromatoidal material is available. Presence of glycogen vacuoles is also seen in the cysts (Giboda, 1988). The trophozoites size generally ranges between 12 -18 µm and are mostly spherical in shape. When trophozoites are stained, its nucleus with a small karyosome is visible. The chromatin on the periphery is often seen to be distributed in form of granules.Its motility is identical to that of E.coli. Life Cycle This parasite resides in the intestine of humans and completes its life cycle within the host. This parasite has two stages- cyst and trophozoites. When the host ingests matured cysts accidently the cysts enters the intestinal path of the host. The uninucleated host undergoes maturation and it excysts within the intestine to release trophozoites. The trophozoites that are released migrate gradually to the large intestine. Trophozoites now undergo simple binary fission to form more cysts. Both cysts and trophozoites are passed out along with faeces. Cysts are found in normal stool while trophozoites are found in diarrheal stool. The main cause of infection is ingestion of the cysts. Even though both trophozoites and cysts are excreted out along with faeces it is the cysts which is able to survive in hard and unfavourable conditions owing to the presence of a protected wall. On the other hand, trophozoites barely survive once they are excreted out of the body and even if they are ingested before they die the acidity of the stomach kills them. Therefore, the protected cysts are primarily responsible for transmission and spreading of the infection. Epidemiology Infections caused by E.polecki are considered very rare. The organism is found all around the world but it is more prevalent in certain areas such as Papua New Guinea and South East Asia. The disease was not very much prevalent in the U.S. however infection was detected in South Asian refugees who enter the United States. Therefore the number of patients suffering from the disease in the U.S. has increased in the past few years (Gay et al, 1985). Transmission of the parasite may be from human to humans or from pigs, monkeys and other domesticated animals (Maguire et al, 2013). Humans get infected by accidental ingestion or contact with stools containing cysts of the parasite from infected animals. According to a research study it was established that rate of man to man transmission was high which increased the prevalence of the disease increases as well. Clinical Symptoms Being a rare kind of infection the clinical manifestations of the parasite have not been studied in details and is considered to be asymptotic in most patients. Not much is known about the incubation period either however, researchers believe that being almost identical to other Entamoeba species the incubation period for this particular parasite is same as that of other members of the Genus and therefore may range between few day to weeks depending on the infection intensity. One human case was studied closely and it was observed that the infection did not give rise to any observable symptoms for over 3 years (John and Petri, 2006).The most common symptom that is present is diarrhoea. Along with diarrhoea other symptoms such as anorexia, mucoid stools, eosinophilia and chronic abdominal cramps have also been seen in some cases. Laboratory Diagnosis The most widely used method for laboratory diagnosis is identification of trophozoites in the stool samples using microscopy. However such identification is not always possible and accurate since there exists morphological similarities between all of the Entamoeba species. In fact morphologically E.polecki may mimic pathogens such E.histolytica and E.coli. Even with wet smearing accurate distinguishing is not possible. Normally identification is carried out by observing trophozoites and cysts in stool samples either on concentrated wet mounts and permanent stained smears. Solely trophozoites cannot provide accurate information and hence different stage so the cyst needs to be identified for proper identification at the species level (McGuire et al, 2013). Another important assay namely the Reverse Line Hybridization Assay has recently emerged as an important tool and a standard diagnostic technique for detection of Entamoeba species and its genetic variants in the samples of stools, It requires the assay to be performed after hybridization and amplification with Entamoeba specific primers (Verweij et al, 2003). However several other strategies are employed today for accurate information. Molecular techniques such as nested polymerase chain reaction are utilized to differentiate between the pathogenic and non-pathogenic species for proper diagnosis (Ngui et al, 2012). Conventional PCR and Real time PCR can also be used to differentiate between the trophozoites (Qvarnstrom et al, 2005).Biochemical and serological assays for antigen detection may also be used (Fotedar et al, 2007). Treatment At present, E.polecki infection is treated with the help of medications. Successful treatments occur by administration of three anti-parasitic drugs named- Metronidazole, Ornidazole and Furamide. Metronidazole is considered most effective and a dose of 750mg for 10 days needs to be given to ensure complete eradication of the parasite (Bonilla-Chancin, 1980). This dosage is also followed by 500mg dose of diloxanide furoate for 10 days. Ornidazole and Furamide are known to be effective when sued along with Metronidazole however their efficacy when administered alone is largely unknown. Prevention According to the Centre for Disease prevention, transmission of the parasite may be both faecal-oral or zoonotic in nature and hence prevention strategies maybe implemented keeping these mode in mind. Firstly limited contacts needs to be maintained with animal reservoirs of the parasites such as pigs, monkeys or other domesticated animals. People working with such animals need to adhere to safety protocols and handle the animals carefully and hygienically. At a personal level hygiene needs to be maintained and hands need to be washed with a good medicated soap (Zeibig, 1997). In addition to this animals need to be monitored regularly and checked to look for the presence of pathogens. Moreover, there are other preventive measures that maybe adopted as well. Such measures include careful handling of raw food items, washing and cleaning food items before consumption and proper cooking. If a person has a farm with pigs and other animals he should make sure that the management of the farm is done well and the pens are cleaned regularly. Furthermore proper food and water needs to be given to the animals. The health of the animals needs to be monitored on a regular basis to detect the presence of any kind of pathogens or infections. At the societal level sanitary disposal of faeces and education about intestinal parasites needs to be introduced. References Bonilla-Chancin,L. "Successful Treatment of Human Entamoeba polecki infection with Metronidazole." American Journal of Tropical Medicine and Hygiene 29.4 (1980): 521-523. Gay.,J.D. “Entamoeba polecki infection in Southeast Asian refugees: multiple cases of a rarely reported parasite.” Mayo Clinic Proceedings, 60.8 (1985): 523-530. Giboda,M et al.” Entamoeba polecki: morphology, immunology, antigen study and clinic of the first infections in Czechoslovakia.”Folia parasitological 35.1 (1988):11-16. Fotedar, R. et al. “Laboratory Diagnostic Techniques for EntamoebaSpecies.” CMR 20.3 (2007): 511-532. print. John,D.T. and Petri, W.A.”Medical Parasitology.”(2006). Missouri : Elsevier Saunders. McGuireJ., et al.” Hunter's Tropical Medicine and Emerging Infectious Disease.”(2013). China: Elseveir Saunders. Ngui,R. et al. “Differentiating Entamoeba histolytica, Entamoeba dispar andEntamoeba moshkovskii using nested polymerase chain reaction (PCR) in rural communities in Malaysia.” Parasites & Vectors5 ( 2012):187 -195.  Qvarnstrom,Y., et al.” Comparison of real-time PCR protocols for differential laboratory diagnosis of amebiasis.”J Clin Microbiology 43.11 (2005): 5491-5497. Verweij,J.J., et al.” Detection and Identification of Entamoeba Species in Stool Samples by a Reverse Line Hybridization Assay,” Journal of Clinical Microbiology 41.11 (2003): 5041- 5045. Zeibig,E.”Clinical parasitology: A Practical Approach.”(1997), USA: Sunders.print. Read More