The Biology of Sexually Transmitted Diseases - Research Paper Example

The Biology of Sexually Transmitted Diseases The term STD is common in today's society. It is the acronym which stands of for "sexually transmitted disease". Taking a close look at the Biology of STDs will allow us to understand a bit better how they work and why they are so dangerous. It is not fully understood why, but human immune systems are simply not able to single handedly fight off STDs. This is why detecting and treating early, suspicious signs of STDs are crucial. Most STDs are transferred through bodily fluid during sexual activity. This is why the use of latex condoms should be used at all times outside of monogamous sexual relationships. Let us first examine an STD that remains a frightening epidemic and is usually a slow death sentence: "It is estimated that 14 million people worldwide are infected with HIV, and there were 2.5 million documented AIDS cases in early 1993" (Nye 1). "HIV attacks the type of lymphocyte known as helper T cells." (Mader 908) HIV (human immuno deficiency syndrome) is a member of the retrovirus family. It is called a retrovirus because it is in a class of viruses which literally imbed themselves into host DNA. It is important to note that any virus that alters DNA can also cause cancer. The altering of host DNA is done when the viral RNA undergoes a process which is almost inverse to DNA and RNA transcription in normal cell division. This reverse process works when an enzyme called reverse transcriptase synthesizes is used by the viral RNA to produce a DNA strand. It is this strand that ultimately becomes part of host DNA. When that host DNA is then transcribed into viral proteins from mRNA, the virus essentially is then a part of the host DNA. Once this takes place, the virus begins affecting the host's immune system. The HIV virus binds to markers on immune system cells called CD4 markers. Once an individual is infected with HIV, their immune system is progressively annihilated by the virus. The paradox of HIV is that while the immune system cells effectively destroy virus particles, the virus continues to reproduce itself such that more viral particles are produced. In addition, the immune system continues to destroy cells infected by the virus but more cells are then produced as replacements. This continues until the patient does not regenerate as many immune system cells such as T cells. Eventually, the patient becomes infected with something as simple as the common cold or flu and does not have the immune system capabilities to fight it off. This often results in death. There are in fact three stages to AIDS. They are referred to as categories A-C. From the time of infection through year 1 is represented as category A. This is a time of little to no symptoms, but the spreading the disease through sexual activity to others is likely. Category B is characterized by flu like symptoms, swollen lymph nodes and herpes-like outbreaks. This period lasts about 8 years. It is during category C that patients are considered to have "full blown AIDS" and typically fall victim to infections that become lethal. There are new drugs on the market that AIDS patients can take to prolong their life span to some degree. Not all sexually transmitted diseases are as aggressive and life threatening as HIV and AIDS but can still cause irreparable damage to the patient. An example of this is Herpes. This virus remains in the body indefinitely. There are two types of Herpes. Herpes Simplex Virus 1 and Herpes Simplex Virus 2. The fist kind of herpes is usually responsible for cold sores while the type 2 form causes genital lesions or genital herpes. Type 2 herpes is more sever and also less common. Type one herpes is spread through mucous membranes when infected partners engage in oral sex. The herpes virus usually takes between 4 and 10 days to incubate. In occurrences of breakouts, lesions form which fill with fluid. This fluid's content is cells which have been infected with the virus as well as inflammatory cells. The fluid filled lesions usually last from 2-3 weeks. Many individuals can be infected with herpes virus and not be aware of it. A characteristic of herpes is a latency period (a period of time with no symptoms). Once a breakout involving lesions has occurred, the herpes virus then passes through the body to the ganglia. The virus uses sensory neurons as a mode of transportation. Once inside the ganglia, the virus may then replicate. If replication occurs, which sometimes it may not, the virus can later be reactivated by some sort of outside stimuli. Examples of stimuli are stress, UV light or radiation exposure, menstruation, disruption to immune system and other factors. When this happens, herpes can actually become fatal as the new infection that has spread will often travel to major organs including the brain. On the rare occasion that herpes affects the gray and white matter of the brain, it is called herpes encephalitis. Most cases of herpes are very mild however and do not result in death. It is important to note that, again, herpes does remain in the system of the host for the duration of the host's life span, even in no recurrences of outbreaks. Pregnant women that are positive for herpes may pass the virus on to their new born babies in the event of vaginal deliveries. We have just examined the biology of two sexually transmitted viruses, but viruses are not the only microbe transmittable sexually. Chlamydia Trachomatis (also called C. Trachomatis) is a bacterium responsible for the STD known as chlamydia. Outbreaks of chlamydia can often result in NGU (nongonococcal urethritis). Symptoms of this infection include discharge from genitals and sometimes a slight discomfort of the penis. It is important to note that it is very possible to experience no symptoms with NGU breakouts. This can however cause sterility in men as the epididymis (part of male anatomy that allows sperm to pass through the testes) to swell. Sterility in women can also result after PID (pelvic inflammatory disease). PID is often a result of NGU in women suffering with chlamydia. Since chlamydia is a bacteria, it is treatable with antibiotics such as tetracycline and sulfa antibiotics. Another organism responsible for spread through sexual activity is syphilis. Syphilis is a well known disease as it was contracted by famous historical figures such as Fredreich Nitzche and Adolph Hitler. It is relatively treatable today if caught early but many years ago, people that contracted syphilis often died. Syphilis, is caused by a spirochete known as Treponema pallidium. This organism can be transferred through saliva as well as bodily fluids. Once the organism enters the body, it undergoes a 2-6 week incubation period. Usually, the first symptom is a painless lesion called a chancre. The chancre persists for several weeks and then disappears. This represents stage one of infection. During the second stage, there are no real symptoms except for positive blood tests if tested for syphilis. The third stage lasts about 5 years and is marked by onsets and disappearing of symptoms such as chancres. This is a period where the patient is contagious and will infect others when bodily fluids are exchanged. The next stage is a secondary latent stage and can even result in negative blood tests. The final stage which some patients never progress to, is called the tertiary stage. This stage is characterized by widespread organ damage including damage to the brain. In this case, the disease is referred to as neurosyphilis and is characterized by meningeal thickening and formation of gummas (granulomatous inflammation). The damage caused by neurosyphilis to the brain often results in paralysis, ataxia and insanity. Once the disease has reached this stage, the patient is terminal. Unfortunately, many patients suffering from the initial symptoms of syphilis, chancres on the genital or cervix, do not seek medical attention. Once the disease is allowed to progress to a tertiary stage, the onset of organ damage tends to resemble a myriad of other diseases and is then much more difficult to diagnose. Many individuals have died from this disease in times passed prior to the advent of antibiotics. When testing a patient for syphilis, "Diagnostic tests include fluorescent antibody and treponemal immobilization tests" (Black 711) are common. Treatment for Syphilis is as simple as a few rounds of common antibiotics as penicillin or tetracycline. Gonorrhea is another bacterial STD spread from partner to partner via bodily fluids. Gonorrhea is caused by the bacterium Neisseria Gonnorhea or N. gonnorhea. It is important to note that part of what characterizes this organism is its pili or fimbriae. The fimbriae is a structure possessed by the Neisseria as a means to "hang on" to host cells, mainly epithelial cells. The pili or fimbriae allow the microorganism to cling to epithelial cells so that they are not "sloughed" off or flushed out like in the urethra. Also, these structures can allow the bacteria to cling to sperm cells. Many bacteria are so destructive because of their endotoxins. Different endotoxins are specific to different bacteria and range in severity. The endotoxin specific to gonnorhea is particularly damaging to the reproductive systems of women. These endotoxins directly affect the mucosa located in fallopian tubes. In addition, these endotoxins are responsible for the release of enzymes which are key players in pathogenesis. An individual carrying gonnorhea can remain a carrier for up to 15 years. To acquire an infection by this organism, only a small number of actual organisms at time of infection are necessary. "Gonococci adhere to neutrophils and are phagocytized by them. Phagocytosis kills some of the bacteria but survivors multiply inside PMNLs."( Black 707). Gonnorhea is also a bacteria that can survive in the presence of inflammatory cells. It can also cause pelvic inflammatory disease like other STDs. In males, a greenish discharge may present from the penis along with discomfort and pain. Most normal flora found in human genital secretions are gram negative strains. Though gonnorhea is far from normal flora, it is also gram negative. Because of this, a more differential diagnostic test is necessary for accurate diagnosis. "The ELISA assay has been largely replaced in many laboratories by a newer DNA probe assay (Gene Probe, San Diego, Calif.) with a chemiluminescent detection system for direct detection of gonococcal ribosomal RNA (rRNA) in genital and conjunctival specimens." (Forbes 600). This test is capable of producing results in about 2 hours which cuts down on the 24-48 hour wait on cultures. Yet another sexually communicable disease is genital warts. "Genital warts are caused by the human papillomavirus (HPV)" (Mader 908). There is no known cure for this virus and it can often present with no symptoms. In some cases however, lesions that appear wart- like will appear on the penis of vulva of patients. The warts can often times be removed through surgery. It is believed at this time that HPV is the cause of almost all cases of cervical cancer. Yeast infections are common in many women but are still considered to be an STD of sorts. Vaginitis is the medical term for a yeast infection and is caused by a type of protozoa known as Trichomonas Vaginalis. This organism is usually passed to women from men showing no symptoms. It can also occur in women on certain types of medication or with an imbalance of normal flora. The symptoms often experienced by women include discharge, itching, and odor. Hepatitis is yet another group of viral infections spread through bodily fluid exchange. Some forms of hepatitis can be spread through fecal contamination as well as sexual contact, but for the purpose of this paper we will only look at hepatitis spread through sexual contact. Patients suffering from hepatitis infections often suffer liver damage. They can also suffer from cancer as a result of the hepatitis and certainly death. We will begin with a look at the biology of hepatitis B. Once a patient becomes infected with hepatitis B, the virus incubates for a period of about 3 months. The virus replicates itself in the liver of the patient as well as tissues responsible for blood formation and lymphoid tissue. Symptoms may include flu like symptoms such as malaise, nausea and other stomach upset. This may persist for weeks in some patients. There does exist a vaccine for hepatitis B, which is specifically helpful to individuals working in medical situations where they are frequently exposed to the bodily fluids of patients. Medications that exist on the market at this time are helpful in reducing the onset of symptoms but do not rid the patient of the virus. Like some of the other sexually transmittable viruses we have examined, Hepatitis B is not curable. The patient will always be a carrier. The other strains of Hepatitis such as hepatitis A, C, E and D are not considered to be STDs as the are usually transmitted through contaminated water or other not sexual avenues. As we have seen through this research paper, most sexually transmitted diseases affect women more adversely than men. Women who are pregnant or become pregnant and are positive for an STD can in many cases transfer the disease to their new baby. This often happens as the baby exits through the vaginal canal. Women who are positive for an STD are typically advised by their physician to undergo a cesarean delivery to reduce risk of transfer of the disease to the baby. In the case of STDs caused by bacteria or other microbes, antibiotics can usually produce a cure for the patient but in the case of viral infection, no cure exists. The use of condoms prevents the exchange of semen, vaginal fluid and anal secretions making the risk of contracting an STD much lower. It is essential to use condoms when having any type of sexual intercourse outside of a monogamous relationship. In addition, regular testing for STDs is highly recommended as early treatment of most can prevent progression and further outbreaks. Works Cited Becker, Wayne, Kleinsmith, Lewis, & Hardin, Jeff. (2003) The World of the Cell. New York, Pearson Education. Black, Jacquelyn. (1996) Microbiology: Principles & Applications. New York, Prentice Hall. Forbes, Betty, Sahm, Daniel, & Weissfeld, Alice. (1998) Diagnostic Microbiology. St. Louis, MO, Mosby, Inc. Mader, Sylvia S. (1998) Biology. Boston, MA, McGraw-Hill. Nye, K.E., Paskin, J.M. (1994) HIV and AIDS. Bios Scientific Publishers. Read More