Disclaimer: The designations employed and the presentation of material throughout this publication do not imply the expression of any opinion whatsoever on the part of UNESCO concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. The ideas and opinions expressed in this publication are those of the authors; they are not necessarily those of UNESCO and do not commit the Organization. Citation: Ponce-Gordo, F. Balantidium coli. In: J. Rose and B.
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Disclaimer: The designations employed and the presentation of material throughout this publication do not imply the expression of any opinion whatsoever on the part of UNESCO concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.
The ideas and opinions expressed in this publication are those of the authors; they are not necessarily those of UNESCO and do not commit the Organization. Citation: Ponce-Gordo, F. Balantidium coli. In: J. Rose and B. Fayer and W. Acknowledgements: K. Summary To date, Balantidium coli is the only ciliate protozoan reported to infect the gastrointestinal track of humans.
The parasite can infect a wide range of mammals, pigs being the main reservoir. The organism has also been found in some birds. In most cases, B. Transmission from one infected individual to others is by a fecal-oral route in which contaminated drinking water or food are the main modes of transmission. Close contact with pigs and poor condition of the water sources are the main risk factors associated with the infection by the parasite.
Control measures includes the identification and treatment of infected people, the safe disposal of excreta both of human and animal origin , avoiding the use of night soil as fertilizer for vegetables to be consumed raw, and the improvement in the quality of the water sources. There have not been any specific studies about B. The protozoan ciliates of the genus Balantidium are transmitted by a fecal-oral route in which cysts are the infective stage.
Balantidium cysts can be present in temperate and tropical surface waters worldwide. Among the species in this genus, there is only one infecting humans, Balantidium coli, and no subspecies, serotypes, or genetically diverse types have been named to date.
The main reservoir of this species is swine. Human infections are related worldwide in relation to low sanitation or to contamination of drinking water sources with human and animal especially swine feces. Most infections are asymptomatic, but the organism could in some cases produce a severe infection and even the death of the host, usually associated with other concurrent illness. Waterborne transmission has been documented in some cases 1 Epidemiology of the disease and pathogen 1.
It is possible that these numbers are an underestimation of the real situation as the parasite is considered usually asymptomatic and most reports and statistics are based on data from symptomatic or compromised patients Cooper and Guderian, ; McCarey, ; Nuti et al.
Trophozoites inhabit the intestine, feeding on bacteria and other intestinal contents. In most cases, infections are asymptomatic and the infected host shows no clinical signs, suggesting that this ciliate is an opportunistic parasite that could take advantage of the weakened status of the host caused by other infections, lesions, or diseases.
In such cases, the parasite could invade the intestinal wall causing the disease known as balantidiasis or balantidial dysentery. In most of the human patients with extraintestinal balantidiasis, a concurrent intestinal infection was usually not diagnosed Anargyrou et al.
Anargyrou et al,. In the last few years, several cases have described the presence of B. The economic importance of balantidiasis is not well determined. In different studies it has been suggested that B. There are no data regarding the economic status of balantidiasis in humans. The first formal description of this organism was reported as Paramecium coli by Malmsten in Malmstein, but soon afterwards it was renamed as Balantidium coli by Stein in Stein, Some proposals to change this name were made during the 20th century but they were not accepted until recently.
Chistyakova et al. Because the nomenclature is under revision and to avoid confusion for the readers, we use the name that remains accepted worldwide and is commonly used in the scientific and medical literature - Balantidium coli.
Based on morphological differences of specimens gathered from different host species, or from results of cross-infection studies, some researchers proposed that isolates from pigs, guinea pigs, camels and several non-human primates were different species e.
Such morphological differences could be related to differences in growth conditions Levine ; this nutrient-related variability has been also observed in in vitro cultures Barbosa et al. Failures by some authors in cross-infections studies i. But most of these species have been considered synonyms of B. However, Balantidium suis from pigs and Balantidium caviae from the guinea pig have infrequently been used in publications until recently Schuster and Ramirez-Avila, Recent genetic analysis with isolates from pigs, gorillas, and humans Ponce-Gordo et al.
A mouth-like opening, the cytostome, is located in the anterior part of the cell. There is an elongate or kidney-shaped macronucleus usually located in the posterior part of the cell and a smaller, round micronucleus which usually overlaps the macronucleus and is not easily observable. Some vacuoles can also be seen in the cytoplasm. In stained cysts the macronucleus and some vacuoles can be easily identified and, occasionally, cilia can be seen. Figure 1 Balantidium coli trophozoite from a pig sample, unstained.
Figure 2 Balantidium coli cysts from a pig sample. Left: Unstained cyst. Balantidiasis is considered a waterborne and foodborne disease. The parasite is transmitted by the fecal-oral route, with the cysts, and possibly but less likely the trophozoites, being ingested with fecally-contaminated water and food.
It has been considered that the trophozoites of B. However, recent studies on captive great apes infected with B. The cyst wall provides protection from stomach acid. Outbreaks of balantidiasis are rare. In Persia, 87 cases were thought to be caused by human-to-human transmission among Muslims in an oil refinery town, whereas the outbreak in Truk affected persons after a devastating typhoon that caused widespread contamination of water supplies with pig feces.
As a waterborne parasite, B. In countries with high sanitation standards, transmission is mainly due to an occasional contamination i. The parasite has been described in a wide range of mammalian hosts other than humans, including non-human primates, pigs and wild boars, cattle, sheep, goats, camels, equids and rodents Hegner, ; Levine, ; Levine ; Balantidium infecting ostriches and rheas might also be B.
On the other hand, Balantidium species from poikilothermic hosts have been erroneously reported as B. The most important reservoirs are the domestic pig and wild boars. Other hosts potentially important in the transmission of B.
Domestic pigs are infected worldwide with B. In pigs, these ciliates are non-invasive and non-pathogenic Schuster and Visvesvara, Among the studies, prevalence and the intensity of infection varied between gender and age groups and in some cases opposite results were found between the studies, but probably the main factors affecting infection rates were the management practices at each farm and the veterinary care Schuster and Ramirez-Avila, In general, facilities with cement floors, adequate cleaning protocols, and sewage disposal reduced the prevalence among pigs Ismail et al.
There are very few studies on the prevalence of B. Other suids such as the Central American tapir has been found infected with B.
The epidemiology of B. Although pig farming is forbidden in Muslim countries, human balantidiasis exists in some regions, such as Iran Solaymani-Mohammadi et al. It has been proposed that wild boars might act as the main reservoirs Solaymani-Mohammadi et al.
In Iran and neighboring countries, the parasite has been found in cattle and buffaloes Mirzaei and Khovand ; Samad, ; Tarrar et al. Balantidium coli has been found in several rodent species.
Rats have been considered as a possible source of infection of B. Other rodents, such as the lowland paca Cuniculus paca which is raised as a source of proteins in some Central American countries, can harbor this ciliate Matamoros et al. Matamoros et al. According to experimental infections in piglets and non-human primates, the incubation period ranges from 3 to 6 days Yang et al. Pig-to-human transmission was recorded in areas where humans live in close proximity with domestic pigs and even share habitation Ferry et al.
In most cases, people at greatest risk live in poor hygienic conditions Barnish and Ashford, ; Esteban et al. Others at risk work in abattoirs where pig intestines are handled; farmers working with pig feces; zookeepers working with apes carrying B. In regions where pigs are not reared such as Muslim countries, the contact with other reservoirs such as wild boars, camels, small ungulates or equids could be the source of infection.
In all cases, a poor hygienic environment or poor personal hygiene see below — hygiene measures would facilitate both the animal-to-human and the human-to-human transmission. Another important factor is the health status of the person, which is of paramount importance for the onset of the infection and of the disease.
This includes the physical condition, concurrent pathologies, immunological status and immunodepression Anargyrou et al. Balantidium coli is usually detected in persons with other infectious agents other protozoa, helminths, bacteria, viruses , with systemic diseases, or suffering malnourishment. All of these conditions complicate the medical management and the prognosis Walzer and Healy, Although there is no conclusive evidence that these other infections render the host more susceptible to B.
Other factors that might facilitate balantidiasis include the virulence of B. Human infection is rare in temperate areas and in industrialised countries Ferry et al. In France a clinical case of balantidiasis in a not immunocompromised patient, who lived alone, with no history of travel or chronic inflammatory bowel disease was recently reported Bellanger et al.
The patient was not working in contact with animals. He reported having been on a hike the previous weekend during which he had drunk water through a polyurethane hydration pouch bladder.
The patient insisted that he did not refill the hydration system during the hike. Because it is unrealistic to attempt to render reservoir animals mainly pigs B. Chlorine, at concentrations normally used for ensuring water safety, is not effective against cysts of B.
Water boiling is acceptable. Individual hygiene measures include washing hands with soap and clean water after being in contact with reservoir hosts or before handling food, and washing fruits and vegetables with clean water. Since then, the use of antibiotics has clearly improved the prognosis and now most fatal cases are associated with another concurrent pathology.
Se desplaza por el medio gracias a las corrientes que origina el movimiento de los cilios que recubren su cuerpo. Puede llegar a medir micras. Presenta una boca primitiva, que se conoce con el nombre de citostoma, la cual se complementa con una especie de tubo digestivo primitivo, conocido como citofaringe. De igual forma presenta otro orificio para excretar desechos que se llama citoprocto. Por otra parte, el quiste es de forma oval y puede llegar a medir 65 micras. La pared que los recubre es muy gruesa.
Balantidium coli: características, ciclo de vida, morfología