Disease History, Etiology, and Symptoms

Disease History: 

Microscopic Photo of Chlamydia trachomatis (6) 

Genital Chlamydia is the the most common sexually transmitted disease in the United States and worldwide today(2). The first case of chlamydia reported was in 1907 by Stanislaus von Prowazek in Berlin. (4) 
The genus "chlamydia" includes : Chlamydia pneumoniae, Chlamydia psittaci, and Chlamydia trachomatis (5). Chlamydia trachomatis is the causative strain/pathogen for the STD we know as Chlamydia or "the Clam" in slang. Humans are reservoirs for the bacterium Chlamydia trachomatis(2).  
Interestingly, the word "chlamydia" comes from the greek word "chlamis" which means cloak. The word "trachomatis" is a greek word for rough or harsh (4). The word goes along well with the disease because the STD is known to have little to no symptoms in some individuals. Additionally, the disease is also known as "rough" or "harsh" because it has very bumpy, or rough exterior, as seen in the picture above(2). 

Disease Etiology

Life cycle of chalmydia trachomatis (10)

Chlamydia trachomatis  is a gram negative bacterium that lacks peptidoglycan(5). It has an coccus shape, non motile, and non spore forming (7). Since this bacteria lacks peptidoglycan it is not susceptible to the antibiotic penicillin(5). The mode of action of penicillin is to break down the enzyme that link the peptidoglycan cell wall together (6). However, since the bacterium completely lacks peptidoglycan the antibiotic is completely ineffective. Instead, drugs like azithromycin  and doxycycline are used (9).

This STD has two different stages, the elementary body and reticular body. 

The elementary stage occurs when the initial infection is established. Bacteria in the elementary stage are much like endospores because the outer membrane is highly resistant to the harsh environment (8). Once the elementary body has found a new host (epithelial cells), the host cells engulf the bacterium and the elementary body transitions into a reticulate (non infectious) body. In this state the bacterial must use the host cells ATP to reproduce. Since the bacterium is cloaked instide the hosts cell, the host’s immune system cannot clear the infection. After the reticulate bodies have divided to become elementary bodies they are released from the cell through exocytosis and go on to infect more cells(5). The life cycle is depicted in the picture above. 

Symptoms

CDC STD Surveillance, 2014

The symptoms of Chlamydia are very similar to other STDs such as gonorrhea. Symptoms in women are only seen about 20% of the time(9). However, some symptoms can be seen such as vaginal discharge, abnormal vaginal bleeding, fever, and dysuria. Males only have symptoms 50% of the time. These include urethral discharge, dysuria,swelling, and itching around the testicles(9). Some factors that influence the infection are : unsafe sex(no condom), and previous/present STDs(3). The STD can be detected using DNA/RNA amplification of chlamydia through urine or urethral/vaginal swabs (11). The CDC collects information on STD's yearly and has reported that women have higher rates of chlamydia than males(1). A statistic from 2014 is placed above. It is believed that this disparity is caused by a combination of factors, such as biological differences between males and females, and higher STD screening rates among women (1). Regardless of the reasoning behind the disparity, Chlamydia continues to be the most common STD because of its lack of symptoms (2). From BSCI348M class we know that these statistics are usually unrepresentative of the actual population since these diseases are often under reported. 

Sources:

(1) http://www.cdc.gov/std/chlamydia/

(2) http://jid.oxfordjournals.org/content/201/Supplement_2/S190.full

(3) http://www.prostatitis.org/chlamydia.html

(4) http://www.austincc.edu/microbio/2704q/chlam.htm

(5) http://web.clark.edu/tkibota/240/Disease/Chlamydia.pdf

(6) http://www.iflscience.com/health-and-medicine/strange-history-and-future-chlamydia-vaccines

(7) BSCI443 Lectures

(8) BSCI348M Lectures

(9) http://emedicine.medscape.com/article/214823-medication#2

(10) https://microbewiki.kenyon.edu/images/thumb/a/a0/TaraMcIntyreLifeCycle.jpg/300px-TaraMcIntyreLifeCycle.jpg

(11) http://www.webmd.com/sexual-conditions/guide/chlamydia

Review of a Popular Media Piece

The Strange History and Future of Chlamydia Vaccines

Chlamydia vaccine picture, google (2) 

The purpose of this article is to provide background on failed attempts to develop a vaccine against Chlamydia, as well as a promising new approach to vaccinating against this disease(1). The difficulty in making a vaccine for Chlamydia is because it is not a species, it is a genus. The human pathogen Chlamydia trachomatis, is the cause for the most common sexually transmitted disease in the United States (3). 
The article describes the reason the initial vaccine trials failed. This theory was proposed by Harvard Professor Ulrich von Adrian. Most vaccines are given intramuscularly, which is the reason Dr. von Adrian believes the previous vaccines have failed. Since Chlamydial infections are naturally introduced through the mucous membranes, intramuscular delivery of the vaccine confuses the immune system. 

The article does not make it clear whether or not there are publications or specific research that support this, rather, it completely relies on Dr. von Adrian’s word. I suspect that this article was put together in layman terms, and it can be expected that most of the science behind the method of action would be left out. 

The article also does not provide support for the mechanism of failure for previous vaccine trials: it simply states that "it confuses the immune system." (1) It references an article that von Adrian published in Science describing the mechanism and success of a vaccine that not only cures infected mice of chlamydia but cures it faster than mice who did not receive the vaccine but had developed natural immunity. The explanation of the effective new vaccine does not relate back to von Adrian’s explanation for the failure of 1960’s chlamydia vaccines, but it offers hope for new strategies in vaccine development.

(1) http://www.iflscience.com/health-and-medicine/strange-history-and-future-chlamydia-vaccines

(2) http://media.gradvet.com/uploads/Chlamydia_Packshots[1][1].JPG

(3) http://web.clark.edu/tkibota/240/Disease/Chlamydia.pdf

Review of a Primary Source Article

The relationship between ethnic identity and chlamydia and Gonorrhea infections among low-income detained African american females

Incarcerated woman, google pictures (3) 

The purpose of this study is to explore the relationship between ethnic identity and the incidence of STD like Gonorrhea and chlamydia in detained African American female adolescents. The information for this study was obtained from 123 females in 8 different detention facilities in Georgia(1). The methods they used to obtain the information was an audio-computer assisted self interviewing. This helped decrease reporting bias and reduce problem caused by illiteracy among participants. The measure used to determine strength of ethnic identity was the Multigroup Measure of Ethnic Identity, which asked questions about the importance of ethnic identity in the persons life and the the strength of which they agree with statements regarding their ethnic identity(1). After correcting for other predictors of STIs like age and parental oversight, girls who strongly identified with ethnic identity appeared to be 4.3 times more at risk to contract Gonorrhea and Chlamydia. This is very significant, especially considering girls who participated in HIV risk associated behaviors were only 1.5 times more likely to have Chlamydia or Gonorrhea (1). I chose this article to highlight an at risk population, African Americans. As previously noted, reasons behind the higher incidence of chlamydia in African American populations can be linked to socioeconomic status and stigma.  Socioeconomic status can mean not having transportation or money to pay for treatment against STDs (2).

Characteristics of the sample (1)

The result of this study is very important because previous research suggested that strength of ethnic identity was a protective characteristic because it reduced certain risky behaviors (i.e. cigarette use). The table above shows the characteristics of the sample. Prevalence of Chlamydia and Gonorrhea  infections were 22.6% and 4.3% , respectfully (1). Additionally, 46.3% of the sample reported high ethnic identity (1). 

This study shows that there may also be some negative effects of strong ethnic identity. The authors of this paper noted that this study is limited in that most of the girls came from a poor socioeconomic background and that these results may not be generalizable to the rest of the population(1). Therefore, future studies should use a more socioeconomically diverse population. Another possible study could replicate the study with a different ethnic group, such as those who identify as hispanic, to see if the specific ethnicity affects the relationship under study in this paper.


Sources:


(1) Voisin DR, Salazar LF, Crosby R, & Diclemente RJ. (2013). The relationship between ethnic identity and Chlamydia and Gonorrhea infections among low-income detained African American adolescent females. Psychology, Health & Medicine, 18(3), 355-62. doi:10.1080/13548506.2012.726361

Site of primary source article: http://www-tandfonline-com.proxy-um.researchport.umd.edu/doi/pdf/10.1080/13548506.2012.726361

(2) http://web.clark.edu/tkibota/240/Disease/Chlamydia.pdf

(3) http://www.blackgirldangerous.org/wp-content/uploads/2015/07/prison-woman.jpg

Disease Transmission and Treatment/Prevention

Disease Transmission 

Infant with conjunctivitis from Chlamydia trachomatis (4)

Since Chlamydia is a sexually transmitted disease we know that the disease is transmitted sexually. The bacterium Chlamydia trachomatis attacks epithelial cells of humans, where mucous membranes are found(3). Although the most common area of infection is the urogenital tract infection can also occur in the eyes , the rectum and the respiratory tract (3). Transmission is from person to person through sexual contact.
Specifically, it can be passed through vaginal, anal and oral sex (2). This infection cannot be passed through famine vehicles, meaning it cannot be spread by toilet seats, bed linens doorknobs, or swimming pools (2). Unfortunately this disease can be passed from mother to child, leading to conjunctivitis or pneumonia in the infant (3).To the right we see a picture of an infant infected with chlamydia in his/her eye. 

Anyone who is sexually active can be infected with chlamydia(6). Many are infected and do not know it. The CDC  Estimates that 1/20 sexually active women aged 14-19 have Chlamydia. Although anyone can be infected with chlamydia there are some people who have a higher risk than others. Sexually active young people are at higher risk of acquiring the disease due to behavioral,biological and cultural reasons (5). Many adolescents do not consistently use condoms and move on from one relationship to the next. Since the incubation period of chlamydia can vary from 1-3 weeks, a person may be infected and not know it (5).  If people are not monogamous, or changing partners often, they may pass the infection without knowing. The CDC states that "the higher prevalence of chlamydia among young people may reflect multiple barriers, such as lack of transportation, cost, and perceived stigma. (5)"  Adolescents may not own a car to travel to their local physician, or have money to pay for the treatment, leading to the higher prevalence of the diseases. Chlamydia is the most common STD in Europe and the United states. In 2013, the CDC reported that chlaydia was highest in the the South 5.1 per 100,000 population, followed by the Midwest, the West, and the Northeast(7). In 2014, 48 states were surveyed in the united states and it was found that cases of chlamydia were highest among non-hispanic black men and women(8). This may be due to the differences in socio economic status between african americans and other races (9). 

Treatment/Prevention 

From health classes and BSCI348M we know that the only way to ensure the disease is not spread is by practicing abstinence (5). 

Since this bacterium does not have a peptidoglycan cell wall it is not susceptible to the antibiotic penicillin, which attacks the enzyme that links the wall together (3). Therefore, other antibiotics such as Azithromycin and doxycycline are used (10). In response to the infection the human body produces antibiotics, however since the infection lies within the hosts cells, the immune response will only inhibit the growth of the infection, therefore the antibiotics above are used to clear the disease(4). Doxycycline inhibits the protein production in the bacterial cell, thus restricting the bacterial growth. Azithromycin also inhibits protein synthesis (4). 

As stated previous abstinence is the only sure way to avoid infection with chlamydia and other STD's However, condoms can help to prevent infection (4). Preventative measures have been taken to promote STD testing, specifically in low income areas. Additionally, the health department has made efforts to provide free condoms to promote safe sex (4). Videos like the one above are used to provide information about STDS in endemic areas. 

I personally believe that other preventative measures need to take place. Chlamydial infections are still extremely high today. I believe the measures taken to reduce the infections are somewhat effective, but more need to be done. From a public health perspective, I believe that the highest(at risk) group needs to be educated on the disease and its mode of transmission. Meaning, that high school sex education needs to be more comprehensive rather than just explaining abstinence. Additionally, I believe there needs to be higher availably of STD testing sites, to ensure that people have places to get tested. 

Sources: 

(1) http://www.ncbi.nlm.nih.gov/books/NBK248300/

(2) http://youngwomenshealth.org/2012/11/20/chlamydia/

(3) http://web.clark.edu/tkibota/240/Disease/Chlamydia.pdf

(4) https://pedclerk.bsd.uchicago.edu/sites/pedclerk.uchicago.edu/files/uploads/conjunctivitis_0.png

(5) BSCI348M Lectures

(6) http://www.cdc.gov/std/chlamydia/stdfact-chlamydia-detailed.htm

(7) http://www.cdc.gov/std/stats13/chlamydia.htm

(8) http://www.cdc.gov/std/stats14/tables/11b.htm

(9) FMSC410 Lectures

(10) http://emedicine.medscape.com/article/214823-clinical

(11) https://www.youtube.com/watch?v=6u2oFE2nPlM