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Syphilis



Syphilis is a sexually transmitted Disease caused by a bacterium called Treponema pallidum. It is considered to be the most serious of venereal diseases. This disease has been a part of hundreds of years worth of human history, and probably thousands of years worth of prehistory. It has been written about, debated over, and has affected every culture it has invaded. It is a topic that is still hotly debated today. In 1996, 11,387 cases of primary and secondary syphilis in the United States were reported to the US. Centers for Disease Control and Prevention. Although treatment is available, the early symptoms of syphilis can be very mild, and many people do not seek treatment when they first become infected. Of increasing concern is the fact that syphilis increases the risk of transmitting and acquiring the human immunodeficiency virus (HIV) that causes AIDS. 

T. pallidum was first isolated in 1905 by Schaudinn and Hoffmann in material from syphilitic lesion. This bacterium was described as a spirochete. 

CELLULAR MORPHOLOGY 

T. pallidum is 5 to 20μm  long and 0.1 to 0.2μm broad. The resting spirochete has regular spirals with a wavelength of 1.0μm and an amplitude of 0.5μm. It can readily be observed underdark field illumination. The fine structure of the bacterium has been examined by electron microscope. It contains an axial filament composed of several fibrils wound around the protoplast. The axial filament arises from a base plate in the protoplasmic cylinder, wraps itself around this cylinder end, and terminates with a free end on the envelope. The axial filament is responsible for the characteristic spiral shape of the organism. A lose of the filament leads to the disappearance of spiral shape. The whole cell is surrounded by an envelope. It is quite fragile and is readily disrupted by osmotic shock. 

T. pallidum is stained by Gram method but is hardly visible by light microscopy. Do you know why? The spirochete is very thin structure and its thickness barely exceeds resolution power of the light microscope. However, special staining techniques are available to observe them under tight microscope, such as Giemsa stain, Levaditi stain, Tunicliff stain, etc. The Levaditi procedure of silver impregnation makes the spirochetes readily visible by light microscopy. This procedure is frequently used for staining histological sections of syphilitic lesions.

CULTURAL CHARACTERISTICS 

It is a strange fact that T. pallidum cannot be cultured on laboratory media. There are available many cultured strains of treponemes, for example, the Reiter strain, propagated for many years under anaerobic conditions. These strains are nonpathogenic, though they were originally obtained from syphilitic lesions. It has been stated that T. pallidum grows on laboratory media only after loosing its pathogenicity. Traditionally this organism has been considered an obtigate anaerobe, but recent studies have revealed that it is microaerophilic. 

It is possible to cultivate virulent T. pallidum by inoculating clinical material from the syphilitic lesion on rabbit testicular tissue. The technique of animal inoculation is also employed for the cultivation of pathogenic treponemes. At present rabbits are most frequently used for this purpose. The best-known strain of T. pallidum propagated in rabbits is the Nichols strain. 

RESISTANCE TO PHYSICAL AND CHEMICAL AGENTS 

T. pallidum is very sensitive to temperature; it is killed within 2 hours at 41°C . It is also sensitive to freezing, desiccation, osmotic shock, and extreme acidic or alkaline pH. Many chemical agents are found very lethal for T. pallidum, such as phenol, heavy metals, acids, alcohols, etc. However, it remains alive indefinitely if preserved as a suspension in liquid nitrogen. 

ANTIGENIC STRUCTURE 

The main hurdle in the study of the antigenic properties of T. pallidum is its incultivatibility on artificial media. The study of the patient’s serum has revealed that many different types of antibodies develop during the course of the disease. This indicates one fact: T. pallidum is antigenically very complex. A genus-specific antigen is shared with nonpathogenic treponemes. A species-specific antigen of T.pallidum has not yet been found. It shares a heterophil antigen called cardiolipin that elicits Wassermann antibodies. These antibodies are investigated during serodiagnosis of syphilis. 

PATHOGENESIS 

T. pallidum is spread by direct contact with an infectious moist lesion, usually through sexual intercourse. However, bacteria-laden secretions may transfer the organism during kissing or intimate contact. Skin abrasions provide another possible portal of entry. T. pallidum can not penetrate the intact skin; however, it penetrates the skin or mucous membranes upon prolonged contact. There is rapid transmission of the organism from the mother to fetus after 16 weeks gestation, so that active disease in the mother during pregnancy can produce congenital syphilis in the fetus. 

The initial infection causes an ulcer at the site of infection. The bacterium spreads from the initial ulcer of an infected person to the skin or mucous membranes of the genital area, the mouth, or the anus ot a sexual partner. 

CLINICAL PICTURE 

Medical experts describe the course of the disease by dividing it into four stages: primary, secondary, latent, and tertiary (late). 

PRIMARY SYPHILIS 

The first stage, primary syphilis, is characterized by the development of an ulcer at the site of infection. This lesion is called chancre (“shan-ker”). The chancre can appear within 10 days to 3 months after exposure, but it generally appears within 2 to 6 weeks. lt begins as a single indurated button-like papule,up to several centimeters in diameter on penis. It eventually erodes to create a clean based ulcerated lesion on an elevated base. These lesions are usually painless and located on the part of the body exposed to the partner’s ulcer. They may be apparent in male on the penis or scrotum. Although the chancres can develop on the external genitalia in females, they are more common on the vagina or cervix, and primary syphilis may therefore go untreated. A chancre also can develop on the tongue, lips, or other parts of the body. There is also an accompanying regional lymphoadenopathy. The disease is highly contagious at this stage, but because of the mild symptoms, it frequently goes unnoticed. The chancres disappear within 3 to 12 weeks whether or not a person is treated. If not treated during the primary stage, about one-third of people will progress to chronic stages. 

SECONDARY SYPHILIS 

The time of the secondary syphilis varies even more than primary, ranging in duration from 1 week to 6 months. During this period there is a very pronounced spirochetemia. Secondary syphilis is a systemic disease with metastatic lesions in various organs. It is most often marked by a skin rash that is characterized by brown sores. The rash appears anywhere from 3 to 6 weeks after the chancre appears. While the rash may cover the whole body or appear only on the few areas, the palms and the soles are almost always involved. Other , prominent symptoms include fever, sore throat, stomatitis, nausea, fatigue, headache, loss of appetite, and inflamed eyes. These symptoms may come and go 
for a year, but usually last 3 to 6 months. Secondary manifestations may include atopecia and genital condylomata lata. Condylomata lata are elevated red-brown lesions that may ulcerate and may produce a foul discharge. They range up to 2 to 3 cm in diameter, contain many spirochetes, and are highly contagious. 

LATENT SYPHILIS 

If untreated, syphilis may enter a latent phase, which may last the lifetime of the individual or may progress to tertiary stage. During this phase the disease is no longer contagious and no symptoms are present. However, in some individuals the disease is relapsed during the first 2 or 3 years of latency and the symptoms of the secondary phase reappear. If this happens, the patients may begin shedding spirochetes in the discharge of condylomata lata and become highly contagious. The late latent period of the disease is usually noninfectious. 

TERTIARY SYPHILIS 

Tertiary syphilis is a delayed response of the untreated disease. It can occur as long as 20 years after the initial infection. Only about one-third of those with untreated syphilis progress to the tertiary stage of the disease and one-half of these develop symptoms. When syphilis does progress to the symptomatic tertiary stage, it usually takes one of three forms: 

* Development of localized destructive lesions called gummas. 

* Development of the cardiovascular lesions. 

* Devetopment of central nervous system lesions. 

Gummas 

The syphilitic gumma is a peculiar rubbery necrotic lesion that is caused by noninflammatory tissue necrosis. Gummas can occur singly or multiply and vary in size from microscopic lesions to large tumorous masses. They are most commonty found on the skin, subcutaneous tissue, mucous membrane, liver, heart, testis, and bone. Gumma of the skin is a painless, indurated, and firm nodule that is seated. Gumma of the subcutaneous tissue is an ulcerated mass that appears on the leg, hand, scalp, or face. Gumma of the mouth may cause Perforation of the hard palate as well as deformities of soft palate and uvula may also lead to the inflammation of the tongue followed by a severe fissure. 

Gumma of the mucous membrane may lead to the destruction of the underlying tissue such as bone and cartilage. 

Cardiovascular syphilis 

Cardiovascular involvement usually results from scarring of the medial layer of the thoracic aorta. The prognosis for cardiovascular syphilis is death. This is due to the aneurysms in the vessels of the heart a few months after the development of the symptoms. 

Neurosyphilis 

It is estimated that 3 to 7% of persons with untreated syphilis develop neurosyphiiis. Some persons with neurosyphilis never develop any symptoms. Other may have headache, stiff neck, and fever that result from an inflammation of the lining of the brain. Central nervous system lesions can produce dementia, blindness, or injury to the spinal cord with ataxia and sensory loss (tabes dorsalis).This is a serious disease resulting in pronounced crippling. 

CONGENITAL SYPHILIS 

A fetus may acquire treponemal infection from his mother if she is suffering from syphilis. This type of the disease is called congenital syphilis. This infection usually occurs at the beginning of the second half of gestation, but occasional infections in the first trimester have been well documented. Massive and early infections lead to abortions or stillbirths. With milder infection suffered in later gestational stages the child is born at term with congenital syphilis. Such child may show no sign or symptom of syphilis at the time of birth. However, in many cases papular rashes develop on the entire body of the child. Mucous patches may also develop that may lead to nasal discharge called snuffles. The snuffies may cause deformity of the nose due to inflammation of the bone. This condition is called saddle nose. The disease may involve liver, bones (periostitis), eyes (keratitis), teeth (Hutchinson’s teeth), etc. 

LABORATORY DIAGNOSIS 

T. pallidum can not be cultured. Therefore, diagnosis of syphilis is based on the serological tests or dark-field microscopy with identification of the spirochete in specimens collected from lesions. 

DARK-FIELD MICROSCOPIC DIAGNOSIS 

Dark-field microscopy is considered the most sensitive and specific method in identification of treponemes. Organisms may be found in variable numbers, from primary chancres and mucous patches of the secondary lesions. The lesions of the tertiary syphilis do not reveal treponemes. The specimens, exudative material, for microscopy should be collected before antibiotics are administered. 

SEROLOGICAL DIAGNOSIS 

Seroiogical tests used in diagnosis are either treponemal specific or nonspecific. It should be mentioned that two types of antibodies are produced in response of T.pallidum: a nonspecific nontreponemal antibody called reagin, and a specific; antitreponemal antibody. The regain is a nonspecific antibody that is synthesized not only in syphilis but also in a number of other diseases. It reacts nonspecifically with cardiolipin, an alcoholic extract of beef heart. 

Nontreponemal tests 

The most commonly used nontreponemal tests are the Venereal Disease Research Laboratory (VDRL) and rapid plasma reagin (RPR) tests. The VDRL test is a nonspecific but useful screening test, becoming positive within 3-4 weeks of the primary infection. It generally becomes negative by 6 months after treatment. It is a quantifiable test, which can be used to monitor therapy efficacy and is helpful in assessing disease activity. This test is performed by mixing reagin with serum on a glass slide. Flocculation of antigen is then determined by microscopic examination. The false positive results (showing signs of infection when it is not present) occur in people with autoimmune disorders, certain viral infections, and other conditions. 

The RPR test is a modification of the VDRL test. It also uses a cardiolipinlecithin-cholesterol antigen, but is performed on coated, disposable cards. Flocculation may be visualized macroscopically due to the inclusion of charcoal particles in the antigen suspension. Unlike the VDRL, the RPR test is easy to perform in clinic or office setting. 

Treponemal tests 

These tests are used to demonstrate the specific treponemal antibodies. The currently used tests include the fluorescent treponemal antibody-absorption (FTAABS) test and the haemagglutination tests. 

In the FTA-ABS, antibody is detected by fluorescein-tagged anti-human lgG following reaction of the patient’s serum with whole T. pallidum fixed to a glass slide. The demonstration of brightly fluorescing T. pallidum on the slide when viewed with a fluorescence microscope indicates the presence of anti-treponemal antibodies. 

In haemagglutination tests, the most popular method is microhaemagglutination test for syphilis (MHA-TP). In this method, anti-treponemal antibody is detected by its ability to agglutinate erythrocytes coated with T. pallidum antigen. 

All serological investigations may be negative in early primary syphilis. The diagnosis will then hinge on positive dark-field microscopy and treatment should not be delayed it serological tests are negative in such situations. 

The drugs of choice for the treatment of syphilis are benzathine penicillin and erocaine benzylpenicillin. lntramuscular injections are administered for 10 to 14 days in cases of early syphilis. For late cases, particularly when there is cardio- vascular or neurological involvement, the therapy should be extended to 4 weeks. lf the patient shows allergic reaction to penicillin, tetracycline or erythromycin may be prescribed. 

The prognosis depends on the stage at which the infection is treated. Early and early latent syphilis have an excellent outlook but once extensive tissue dam age has occurred in the later stages the damage will not be reversed although the process may be halted. Symptoms in cardiovascular and neurosyphilis may therefore persist. 

A person usually can no longer transmit syphilis 24 hours after beginning therapy. Some people, however, do not respond to the usual doses of penicillin. Therefore, it is important the people being treated for syphilis have periodic blood tests to check that the infectious agent has been completely destroyed. Persons with neurosyphilis may need to be retested for up to 2 years after treatment. 

Currently, the researchers are trying to develop a safe, effective, single-dose antibiotic therapy for syphilis. Many patients do not like getting an injection for treatment, and about 10% of the general population is allergic to penicillin. 

PREVENTION AND CONTROL 

Most people all over the world now consider prevention to be just as vital to public health as finding a cure. Public health education measures seem to be extremely effective when dealing with syphilis. When the health departments of the countries make a push for education, a drop in the rates of new cases is significantly noted. 

Another key factor controlling syphilis has been routine testing. By promoting the idea that everyone has to get tested, the health departments can remove the stigma attached to testing. Requiring an STD test when people get new jobs, medical procedures, pregnancy consultations and married can do this. This is a public health approach that many people find less offensive or intimidating than searching out ‘likely suspects’ that might carry this disease. 

The history of syphilis has taught us several things. We can see how quick we are to took for someone or something to blame when an epidemic occurs. We can see there is a stigma that is attached to certain diseases and even to the research for treating an ‘unclean’ disease. We can see how the modern medical ideal of a magic bullet might be impossible to achieve. Most importantty, we can see how prevention is a key to control. Over time the focus in dealing with syphilis has gone from finding better treatment to finding better preventive measures. They may include using condoms during sexual intercourse. Screening and treatment of infected individuals, or secondary prevention, is one of the few options for preventing the advance stages of the disease. Testing and treatment early in pregnancy is the best way to prevent syphilis in infants and should be a routine part of prenatal care. 

In an effort to stem the spread of syphilis, scientists are conducting research on a vaccine. Molecular biologists are learning more about the various surface constituents of treponemes that initiate an immune response against the invading organism. This knowledge will pave the way for development of an effective vaccine that can ultimately prevent syphilis . 

By monitoring a disease and predicting those who are at risk, we can implement public education programs. It is only through the efforts of both medical treatment and public health education that syphilis can be controlled.



This post first appeared on Medical Terminology "C", please read the originial post: here

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