Microscopic view of Balantioides coli ciliate protozoa inside a mammalian intestine.

Gut Check: Unveiling the Secrets of Balantioides coli and Its Impact on Animal Health

Lena Voss in Science & Nature June 2025 • 5 min read.

"Brazilian researchers explore the prevalence and genetic diversity of Balantioides coli in captive animals, shedding light on its potential impact on animal health and zoonotic transmission."

In the microscopic world of our guts, single-celled organisms are constantly battling for dominance, some beneficial, others less so. Among these microscopic inhabitants are ciliate protozoa, particularly those belonging to the genus Balantioides. Previously known as Balantidium, these protozoa are found in a wide range of animals and have a complex relationship with their hosts.

Balantioides coli, the most commonly reported species in this genus, can infect humans, pigs, and non-human primates. While often harmless, it can sometimes cause clinical manifestations, ranging from mild discomfort to severe dysentery. Understanding the prevalence, genetic diversity, and transmission of this parasite is crucial for maintaining animal and human health.

A recent study by Brazilian researchers delved into the world of Balantioides coli, examining isolates from both in vitro cultures and fecal samples of captive animals in Rio de Janeiro. By employing molecular tools, the study aimed to characterize these protozoa, shedding light on their genetic diversity and potential implications for animal health and zoonotic transmission.

What is Balantioides coli and Why Does It Matter?

Microscopic view of Balantioides coli ciliate protozoa inside a mammalian intestine.

Balantioides coli is a single-celled parasitic organism that belongs to the ciliate group. Ciliates are characterized by the presence of hair-like structures called cilia, which they use for movement and feeding. B. coli is found primarily in the large intestine of its hosts, where it can exist in two forms: trophozoites and cysts.

Trophozoites are the active, feeding stage of the parasite, characterized by a ciliated plasma membrane. Cysts, on the other hand, are dormant, resistant forms that allow the parasite to survive in the environment and transmit to new hosts. Infection typically occurs through ingestion of cysts in contaminated water or food, or through direct contact with infected animals.

Diversity of Hosts: B. coli can infect a wide range of animals, including humans, pigs, and non-human primates.
Transmission: Infection occurs through ingestion of cysts in contaminated water or food.
Clinical Manifestations: While often asymptomatic, B. coli infection can cause dysentery and other gastrointestinal issues.
Global Prevalence: Although generally low, prevalence rates can be high in certain regions, particularly in tropical areas.

The study aimed to analyze protozoan isolates maintained in culture medium and from fecal samples from captive animals in Rio de Janeiro, Brazil, by means of molecular tools. Forty isolates maintained in Pavlova modified medium (30 were isolated from feces of pigs and 10 from feces of cynomolgus macaques) were analyzed. In addition, 34 fecal samples (8 from pigs, 8 from cynomolgus macaques and 18 from rhesus macaques) containing Balantioides coli-like cysts were analyzed. All samples were subjected to DNA extraction and the polymerase chain reaction (PCR) to amplify the fragment ITS1 - 5.8s rRNA - ITS2, and the PCR products were purified and sequenced. All samples (100%) presented sequences that were grouped in the Balantioides coli cluster. The type A0 variant predominated.

What's Next in Balantioides coli Research?

The researchers emphasize that the differences observed between variant sequences should be viewed with caution, given the limited understanding of this parasite. They advocate for continued use of the ITS1 - rRNA - ITS2 fragment in future molecular-level studies to fill existing information gaps, particularly regarding the parasite's transmissibility among different hosts. This study has provided a foundation and proven the need for continued investigation into molecular epidemiology. Additionally, there is a need to conduct molecular studies on fecal samples from other animal species, including Neotropical primates and humans, to evaluate the profile of these variants and their importance within molecular epidemiology.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/j.vprsr.2017.08.014, Alternate LINK

Title: First Molecular Characterization Of Balantioides Coli (Malmsten, 1857) Isolates Maintained In Vitro Culture And From Feces Of Captive Animals, Rio De Janeiro, Brazil

Subject: General Veterinary

Journal: Veterinary Parasitology: Regional Studies and Reports

Publisher: Elsevier BV

Authors: Alynne Da Silva Barbosa, Francisco Ponce-Gordo, Laís Verdan Dib, Claudia M. Antunes Uchôa, Otilio Machado Pereira Bastos, Alcides Pissinatti, Maria Regina Reis Amendoeira

Published: 2017-12-01

Everything You Need To Know

What exactly is Balantioides coli, and why should I be concerned about it?

Balantioides coli is a single-celled parasitic organism classified as a ciliate, identified by its hair-like structures called cilia. It exists in two forms: the active, feeding trophozoites, and the dormant cysts. Understanding Balantioides coli is important because while infections are often asymptomatic, they can lead to dysentery and other gastrointestinal issues in both animals and humans. Further research is required to fully understand the transmissibility of Balantioides coli.

How does Balantioides coli spread, and what can be done to prevent its transmission?

The primary method of Balantioides coli transmission is through the ingestion of cysts, the parasite's dormant form, found in contaminated water or food. These cysts allow the parasite to survive outside the host and infect new individuals upon ingestion. Balantioides coli can also be transmitted through direct contact with infected animals. Control measures, such as improved sanitation and hygiene practices, are essential in reducing the risk of transmission. More research is required to understand the potential impact of different variants of Balantioides coli on its transmissibility.

Which animals can be infected with Balantioides coli, and what are the implications of its broad host range?

Balantioides coli can infect a wide variety of hosts, including humans, pigs, and non-human primates. This broad host range is significant because it increases the potential for zoonotic transmission, where the parasite can spread from animals to humans. The impact on different host species can vary; while some infections may be asymptomatic, others can result in severe clinical manifestations such as dysentery. Further investigation is warranted to evaluate the impact of Balantioides coli variants in Neotropical primates and humans.

What molecular methods were used to study Balantioides coli, and how do they help in understanding the parasite?

The study used molecular tools, specifically the polymerase chain reaction (PCR), to amplify and sequence the ITS1 - 5.8s rRNA - ITS2 fragment of Balantioides coli DNA. This molecular analysis allowed the researchers to assess the genetic diversity of the parasite in captive animals. It is recommended to use this specific ITS1 - rRNA - ITS2 fragment in the future to fill the information gaps regarding transmissibility among different hosts. By analyzing these genetic markers, the researchers could identify different variants of Balantioides coli and gain insights into their potential origins and transmission routes.

What is the significance of the type A0 variant being predominant in the studied samples of Balantioides coli?

The type A0 variant of Balantioides coli was found to be the predominant one in the samples analyzed. This finding suggests that this particular variant is widespread in the studied populations of captive animals. The identification of predominant variants is important for understanding the epidemiology of Balantioides coli and developing targeted control strategies. Further studies are needed to investigate the characteristics and potential differences in virulence or transmissibility of different variants.