Title : The role of protozoa and metazoa in exacerbation respiratory infections; A review on cellular and molecular symbiosis between protozoa and other pathogens
Introduction: Protozoa are unicellular and eukaryotic microorganisms. Despite the simple cellular structure, it can destroy the hosts bodies during its parasitic life, especially when this life contain symbiosis with one or more other microorganisms. Protozoa have received less attention, but when it enter the body of mammals, especially humans, through water, food, or mucosal tracts, can be important and dangerous. It can live in the mucus and reach to the intended destination through circular systems. One of these destinations may be the respiratory system and lungs. After locating in the respiratory system, these microorganisms destroy host cells during the movement or secretion of some compounds. It can fatal when the patient has a background of respiratory diseases (e.g., asthma or COPD) or involved with an infectious respiratory disease caused by other microorganisms.
Methods: A systematic review was conducted with keywords (e.g., “protozoa”, “interaction”, “protozoan infections”, “respiratory infections”, “microbial symbiosis”) applied in online databases, including PubMed, Web of Science, Scopus, Science Direct, and Google Scholar from December 1997 to Oct 2022. Most relevant papers were retrieved and screened in three phases against inclusion criteria, based on their title, abstract, and their full texts, and eligible records were included in the review.
Results: According to the statistical data, infections caused by protozoa and metazoans usually occur in tropical and subtropical regions and can spread during the transfer of people to other regions of the world. It is effective in the biodiversity of protozoa and bacteria or fungi and their interactions with each other in the hosts. The arrival of protozoa in the lung is a rare occurrence, but the reports of “pulmonary respiratory infection by protozoa” indicates the importance of this issue. The respiratory system of mammals can be exposed to various species of protozoa and metazoans such as Toxoplasma gondii, Echinococcus granulosus, Echinococcus multilocularis, Strongyloides stercoralis and Paragonimus westermanii. Toxoplasma and Cryptosporidium are uncommon, but they can cause lung infections. Furthermore, some species (e.g.,Toxoplasma gondii) directly cause disease by being in the lung parenchyma, but some other species (e.g, Cryptosporidium and Microsporidium) can be seen in the mucosal layers of the respiratory system.
Conclusion: Viruses, bacteria, and fungi are other pathogens of the respiratory system that can cause infection, protozoa can reach the respiratory system and interact with them so can causing the exacerbation of respiratory infection. Symbiosis can drive the development of the protozoa (This type of symbiosis occurs intracellularly). Another type of symbiosis contains the preparation conditions for better growth of bacteria by protozoa. Among the examples, we mention the symbiosis of Trichomonas and respiratory Herpes, Trypanosomida and Rhodococcus rhodnii, Toxoplasma and Teredinibacter turnerae, Coccidia with Bacillus subtilis, etc. In this article, we investigate the molecular mechanisms during the intercellular communications of protozoa and other microorganisms.
Audience take away:
? They can figure out that protozoa and other microorganisms have symbiosis (molecular cell mechanisms).
? They discover the types of protozoa which can live in human respiratory tracts.
? They can imagine how protozoa can access to compounds from bacteria, viruses, and fungi.
? They can improve their knowledge in parasitology and protozoa life cycles in the host body and out of it.