It has come to an end, but before we end, it lets talk about one last thing about Enterobius Vermicularis. In this article, Chen and other researchers are conducting a study to determine the current status of Enterobius vermicularis infection of pre-school children in Taipei, Taiwan along with the associated risk factors with this pinworm infection.
There are some keywords listed by the authors which include the following:
Enterobius vermicularis infection: Also known as pinworm infection that is spread through the finger oral route and inhalation.
Risk Factors: Factors that can cause humans to be infected with pinworms. Examples include bed sharing, carpet, siblings, and level of education by parents
Pre-school children: The participants in the study
Taipei: The study was conducted in Taipei, Taiwan
The authors believe that a positive rate of Enterobius vermicularis is no longer common in many parts of the world and past studies suggest that the pinworm infection among school children has reduced in Taiwan due to the Taiwanese knowing the risk factors from previous studies and eliminating the chances of being infected with Enterobius vermicularis.
The study was conducted over two years that included over 45,000 pre-school participants in Taipei. The study included teachers and kitchen staff in the school that the pre-schoolers attended. To collect a sample, two- consecutive-day adhesive cellophane perianal swab kit was given in the morning to the participants. The collected specimens were examined under the microscope for pinworm eggs or worm. A questionnaire was also given to parents to gather information about the family background, personal hygiene, and household sanitary conditions.
The results show that out of the 45,014 participants, 94 individuals were found to be infected with the pinworm infection. Data indicate that the positive rate of infection was slightly higher in boys than girls. In family, parents of the children that had a lower educational level and have an older sibling(s) had a significantly higher positive rate of the pinworm infection. The study reveals personal hygienic factors that include washing hand habits, finger sucking, long fingernails, and bathing habits did not have any connection to the pinworm infection. Of the personal hygienic factors, participants taking a bath by themselves, bed with matting, and not washing hands after using the restroom, have a high positive rate. The results of the teacher and kitchen staff were all negative for pinworm infection. Also, there are no associations between the style of residence, type of floor, cleaning the house and the bedding, and sharing a bedroom with other family members.
The study indicates that 0.21% of 44,163 pre-school participants were infected with pinworm which is lower than 0.40% in 2007. The results show that there were no significant differences by gender and school, but the rates in boys and kindergartens were slightly higher. The gender difference can be explained by girls have better personal hygienic practices to prevent contracting pinworms than boys. In the beginning, there were a list of possible risk factors that were tested to see if they are risk factors. The study demonstrates the following features are risk factors:
Finger- oral route
Having a(n) elder sister(s) or brother(s)
Bathing without the help of family members
Not washing hands after restrooms
Sleeping on a bed with matting
Since finger- oral route is the main mode of transmission, the article mention that practicing good handwashing habits is the best way to prevent contracting and spreading the infection.
The findings (risk factors) in this study can be applied to other countries to lower the positive rate of Enterobius vermicularis infection. In developing countries that are crowded and undeveloped economically, the knowledge of the above risk factor can help in decreasing the positive rate of the pinworm infection since several studies from the previous year have similar statistics to the corresponding risk factors. The finding of the study is not unusual. Finger-oral transmission is the main mode of transmission because pinworm eggs can be stuck under the fingernails if the individuals do not wash their hands frequently after using the restrooms. Young children are not able to take care of themselves as adults can so allowing small kids to be able to bathe and clean themselves without the help of adults is not a surprising risk factor.
You can read more about the study by clicking the link below:
Phylogeny represents the evolutionary relationships among a taxonomic group of organisms. Inserted below are two phylogenies: one phylogenetic tree displays numerous species within the genus Enterobius and the other phylogeny presents three genera within the family Oxyurata.
Both phylogenies organized the parasites based on the respected host for each species within each group.
The above image displays a phylogenetic tree of species in the genus Enterobius with their corresponding host to the right. Enterobius vermicularis is closely relative to Enterobius buckleyi.
The above image shows a phylogenetic tree of organisms in the family Oxyurate. However, Enterobius vermicularis is closest to Enterobius anthropoiteci.
There are numerous species within the genus Enterobius, all parasites, grouped accordingly by their specific host.
The first phylogenetic tree suggests that E. vermicularis closest relative are E. buckleyi. However, the second phylogenetic tree proposed that E. anthropiteci are the closest relative to E. vermicularis.
As you already know, E. vermicularis can only infect one host, homo sapiens. Specifically, humans in the temperate regions such as Japan and South Korea as demonstrates in the first phylogeny.
It is interesting that the second phylogenetic tree list chimpanzees as an additional host for E. vermicularis even though they have their pinworm species, E. anthropiteci. This can be explained by a study conducted in Japan. In a zoo in Japan, scientists collected feces of captive chimpanzees to test for parasites, and the human pinworm was found in the collected feces, resulting in placing E. anthropiteci closest to E. vermicularis.
Enterobius gregorii, also used human as its host, are not listed in both phylogenies above but supposedly a sister species of E. vermicularis shown in the phylogenetic tree below. This is because this species’ existence is controversial due to insufficient evidence and some believe that E. gregorii is a younger stage of E. vermicularis. Otherwise, evidence indicates that E. gregorii is identical to E. vermicularis with one minor difference; a slightly smaller spicule in E. gregorii.
The image above shows that Enterobius gregorii is the closest relative to Enterobius vermicularis which are not shown in the other phylogenetic trees.
Physiology is the study of normal function within living organisms. Well, Enterobius vermicularis or pinworms, are parasites meaning that they use its host body to survive and reproduce. Then, who is its host? In fact, pinworms only have one host and it is the human body. But how does this species enter the human body to infect its host and potentially other human too?
Again, pinworms require a host to complete its life cycle, and without a host, the pinworm cannot develop and reproduce.
Enterobius vermicularis has a simple life cycle, and this is why it is easy to contract a pinworm infection and even less difficult to transmit the infection to others.
The life cycle of pinworms begins with the eggs being ingested by the human host via contact with surfaces that are contaminated with eggs. The eggs hatch to release larvae that begin to grow to a size of about 140 mm and then migrate into the small intestine, and during that migration, it develops into an adult worm. The female pinworm inserts her pin tail into the mucosa for oviposition. Soon, the body of the female pinworm is filled with 11,000 to 16,000 eggs, and the journey to the anus begins. When the female pinworm is migrating out of the anus, she is depositing eggs on the skin around the anus. The process of laying eggs in pinworms is not quite clear. Scientists believe the eggs can be released from the female pinworms by contraction, or it might occur after the death of the female, and her body disintegrates to release the eggs.
What is interesting about this part of the cycle is that the eggs are laid in a sticky, jelly-like substance and along with the wriggling of the female pinworm, causes severe itching — these characteristics are how pinworms can spread to another human host. By secreting an itchy mucus when laying her eggs and moving on the skin, it triggered an urge to scratch the affected area of the anus or vagina. By the fingers or fingernails, the eggs may be transferred to any surface or human that it is touching and if they are touched, they will be transferred to the hands, and eventually, to the person’s mouth leading to a serious risk of swallowing the eggs and becoming infected. This process allows the spread and re-infection of Enterobius vermicularis.
The photo below illustrates the many eggs that female Enterobius vermicularis lay on the skin. These eggs can be picked up by the humans from scratching and resulting in the spread of the infection to other humans.
The video below shows the movement of a pinworm in a stool sample. The wriggling of the pinworm can cause severe itching for humans leading to scratching.
As you can see, Enterobius vermicularis do not release a toxin or venom to infected its host as some believed. By just touching a surface that has been contaminated by pinworms egg is all it takes to be infected. Furthermore, by just the movement of the pinworm and the ability to secrete mucus allow the pinworm to find its new victims. But remember this cycle can be prevented by practicing good hygiene by merely washing your hands.
Let’s start learning more about Enterobius vermicularis, or pinworms of phylum Nematoda. Why do you think these worms are called pinworms in the first place? You guess it! It is due to the shape of their tail.
The male pinworms are approximately 2-5 mm while the female is larger at 8-13 mm. The defining characteristics of pinworms and what gives it its common name is shown on the female tail. The long, thin pointed tail distinguishes the female worm while the male pinworm has a curved, blunt posterior end with a single spicule.
Pictured above is a microscopic image of an adult female Enterobius vermicularis. The arrow shows how a long, pointed tail characterizes the female pinworms.
Pictured above are two microscopic images of an adult male E. vermicularis. The image on the left shows the posterior end of the tail. The image on the right is a close up of the male and the black arrow points to the esophageal bulb and the red arrow points to the curled posterior tail with a spicule.
If you look at the photo above, paying close attention to the female pinworm, you can see that the vagina and the mouth are not near the tail, so the female worms do not use their tail for reproduction or feeding purposes. Also, pinworms move by wiggling back and forth in the human body without using its tail, and you can see that in the video below. So what is the function of the female tail? The functions of the female pinworm are not known, but the function of the tail of the male pinworms are known. The male tail is curved and blunt with a single spicule. The spicule can be used as a tool to open the vulva of female to transmit sperm, and the curved tail is a way for the male to clasp on to the female during reproduction.
The video shows how pinworms wiggle back and forth to move.
Pinworms also have a double bulb esophagus. The double bulb esophagus is muscular and uses for the expulsion of eggs, but other animals in phylum Nematoda, it is used to pump fluids and foods. The cephalic alae are located at the anterior end and while the function is not known it is related to the enhancement of the cuticle strength, the movement of the worm, and the fat storage.
Hi everybody! My name is Tuyen and I am very excited to be blogging about the phylum Nematoda focusing on the species Enterobius vermicularis, or what people usually referred to as human pinworms or threadworms.
Just telling the truth, but before during my research, I had no idea about this creature existence and I am sure you didn’t either. Good thing we can go through this journey to explore more about pinworms and how it can affect YOU.
To start off, pinworms are small, thin, white roundworms and are commonly found in humans located in the temperate regions of the world (Everyday Health). According to the CDC, pinworms are the most common type of worm infection in the United States. Humans who are found to be infected with pinworms are usually children and the infection is most frequent in crowded conditions such as school, prison, or at home if there is an individual that is infected by pinworms already (CDC).
Well, that is all for today, see you for the next post about pinworms!
