Trichomonas

Trichomonas is typically found in anaerobic environments. It is a known parasite of many different animals including humans, birds, dogs, and cats. In humans, it can be found in the urogenital tract and in the oral cavity. It is estimated that 276 million new cases of urogenital infections occur each year. ==Morphology==

Trichomonas is around 10 μm in length and is normally pear-shaped. It has four flagella at its anterior end, distinguishing itself from closely related organisms that have different numbers of anterior flagella. At the base of these flagella are the parabasal bodies, kinetosomes accompanied by Golgi stacks. The pelta is a sheet of microtubules that curve around the flagellar bases. Posterior to the pelta is the axostyle, is a bundle of microtubules that extends from the anterior end of the organism all the way to the posterior end. The nucleus of Trichomonas is situated close to where the pelta and axostyle meet. Another distinguishing feature of Trichomonas is the presence of an undulating membrane. The undulating membrane is a fin-like extension of the plasma membrane located on the side of the organism. A flagellum that extends to the posterior end of the organism is attached to the outer edge of the undulating membrane. At the base of the undulating membrane is a striated fiber called the costa which is thought to exist for structural support. ==Genetics==

Trichomonas vaginalis, being the species that causes the most complications in humans, is the only fully sequenced Trichomonas species. Through whole-genome shotgun sequencing, the Trichomonas vaginalis genome is estimated to be around 160 Mb long, divided into six chromosomes. However, at least 65% of its genome was found to be redundant. The redundant genetic material is hypothesized to have emerged during Trichomonas's transition from aerobic to anaerobic environments. In addition to discovering the large proportion of repetitive DNA in Trichomonas vaginalis genome, the sequenced genes were also characterized. Approximately 60,000 protein-coding genes were found. Transfer RNAs for all 20 amino acids and approximately 250 ribosomal RNA were all found on the same chromosome. ==Life cycle==

Trichomonas has a trophozoite form, its pear-shaped form, which is most commonly observed, and an amoeboid form, which appears during host colonization. ==Diseases==

Trichomonas causes disease in humans and in birds. In humans, the causative species is Trichomonas vaginalis and Trichomonas tenax. In humans Trichomonas vaginalis is a sexually transmitted disease and causes trichomoniasis. It resides on squamous epithelium of the urogenital tract. Many carriers of Trichomonas vaginalis, especially men, are asymptomatic. Complications for symptomatic women include vaginitis, endometritis, infertility, and cervical cancer. Complications for symptomatic men include urethritis, prostatitis, epididymitis, and infertility. It is also associated with increased risk of transmission and acquisition of HIV. Trichomonas tenax is transmitted through exchange of saliva and contaminated water sources. It is an opportunistic pathogen and may cause pulmonary trichomoniasis. In birds Trichomonas in birds inhabit the upper digestive tract and also cause trichomoniasis. It creates lesions in the trachea and esophagus, occupying space and eventually causing emaciation and asphyxiation. ==Species==

• Trichomonas brixi — inhabits the oral cavity of dogs and cats. • Trichomonas gallinae — inhabits the upper digestive tract of pigeons and doves, but is also able to cause disease in many other bird species. • Trichomonas gypactinii — inhabits the upper digestive tract of scavenging birds of prey, such as vultures. • Trichomonas stableri — inhabits the upper digestive tract of pigeons. • Trichomonas tenax — inhabits the oral cavity of humans. • Trichomonas vaginalis — infects the urogenital tract of humans. (causes trichomoniasis) ==References==