Актуальная Медицина - Sexually Transmitted Diseases (STDs)(Excluding HIV)

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Sexually Transmitted Diseases (Excluding HIV)
Sexually transmitted diseases (STDs) are among the most common reasons for seeking medical care in developing countries accounting for 10% or more of medical consultations in some parts of Africa.
In spite of their serious consequences (particularly for women and children), and increasing evidence that they may facilitate the transmission of human immunodeficiency virus (HIV) through heterosexual contact.
The consequent lack of good facilities for their management has led many patients with these conditions to seek treatment outside the formal health sector, with inadequate treatment regiments leading to increasing antimicrobial resistance among sexually transmitted pathogens.
Epidemiology:
Certain broad generalizations can be made about the epidemiology of STD’s.
• Diseases of the sexually active
• Mother-to-child transmission occurs
• Common among young adults, single people of both sexes
The prevalence of certain STDs among antenatal clinic attenders in a variety of developing countries:
Zambia: Neisseria gonorrhoeae – 11.2%
  Chlamydia trachomas – \-\-\-\-\
  Treponema pallidum – 12.5%
  Trichomonas vaginalis – 38%
Factors contributing to the high incidence of STDs:
1. Demographic factors(young adults)
2. Rural-urban migration with breakdown of traditional customs 
3. Prostitution 
4. Lack of adequate medical services 
5. High prevalence of antibiotic –resistant strains of gonorrhoeae, Haemophilus ducreyi
6. Polygamy
Females who sell sex are a major reservoir of infection in developing countries. Chaneroid remains the most common cause of genital ulceration in many African countries but has almost disappeared from Europe.
Donovanosis (granuloma inquinale) is highly prevalent in certain parts of South Africa.
The lack of reliable and cheap diagnostic tests for the three classical "tropical STDs”, chancroid, donovanotis and lymphogranuloma venereum (LGV) has hindered attempts to study their epidemiology.
Because of the lack of adequate diagnostic and treatment facilities for STDs in many developing countries, complications are common seen, particularly among women and children.
• Pelvic inflammatory disease (PID), due to gonorrhoea or chlamydial infection, is the most common cause of admission to gynaecology wards in Africa;
• Ectopic pregnancy and tubal infertility, another common sequels in some regions of Africa;
• The incidence of carcinoma of the cervix is extremely high; 
• 2-3% of infants develop gonococcal ophthalmia neonatorum; and congenital syphilis is the major cause of hospital admission among infants aged less than 3 months in Lusaka, Zambia.

History-taking and Examination in the STD Clinic

It is not possible to provide a good clinical service for STDs unless one gains the confidence of the patients. This requires privacy and the avoidance of a moralistic attitude.
Sexually transmitted diseases in humans 
When taking a history, the following information should be collected, in addition to name, occupation, address and date of birth:
1. The nature and duration of the symptoms. 
2. The nature of any treatment already taken for this condition 
3. A sexual history, which should include marital status and the nature and frequency of recent sexual contacts with regular or casual partners. This information is essential in order to attempt contact tracing or partner notification. 
4. Past medical history.
5. In female patients a menstrual and obstetric history should be taken.
The examination should be carried out in private in a good light.
• The skin of the abdomen, groins and perineum should be examined in particular for evidence of scabies and pediculosis, and the inguinal glands palpated.
• In males the penis should be inspected, after retraction of the foreskin in uncircumcised patients;
• If a urethral discharge is not apparent, evidence of urethritis can be sought by milking the urethra forward and examining the meatus for discharge;
• The serotum should be palpated for evidence of epididymitis;
• Female patients should be examined in the lithotomy position.
The lower abdomen should be palpated for evidence of PID-masses or tenderness and, after inspection of the vulva, a vaginal speculum should be passed. The cervix should be examined and the speculum then slowly withdrawn while the walls of the vagina are examined.
Bimanual examination should be performed to identify pelvic masses or tenderness;
The presence of pain on moving the cervix (cervical excitation tenderness) suggests the presence of PID.
In both sexes the perianal skin should be inspected and if receptive anal intercourse is suspected, proctoscopy should be performed.
The laboratory investigations requested will depend on the facilities available. All patients with an STDs should be screened for syphilis. Whether they should also be screened for HIV depends on the availability of counselling and of treatment for those to be positive.

Diseases Causing a Genital Discharge 
Urethral Discharge in Males:
Urethritis in males is either gonococcal, non-gonococcal or of mixed aetiology the presence of gonococci is easily demonstrated by Gram stain. 
In most developing countries the majority of cases presenting to hospital are gonococcal. Up to 50% of cases of non-gonococcal urethritis are due to Chlamydia trachomatis;
• A proportion of the remaining cases are associated with Ureaplasma or Mycoplasma species;
• A small percentage may harbour Trichomonas vaginalis;
• Because co-infections with Neisseria gonorrhoeae and C. Trachomatis are common, it is generally advisable to treat cases of gonorrhoea for both gonorrhoea and chlamydial infection when follow-up cannot be guaranteed.
Gonorrhoea:
Gonorrhoea is the most prevalent bacterial STD in the tropics.
The causative organisms: W. Gonorrhoeae, a Gram-negative oval diplococcus found only in man (Urogenital tract, conjuctiva, pharynx, rectum and synovium.
Pathogenesis:
Virulence is conferred by the presence of pili which mediate adherence, sufficient to withstand hydrodynamic forces within the urethra, and which also inhibit uptake by phagocytes.
• Invasion and multiplication has been demonstrated in mucus-secreting non-ciliated cells of the fallopian tubes.
• No specific toxins produced by N. Gonorrhoeae have been identified but the lipo-oligosaccharide and peptidoglycan components have been implicated in inhibition of ciliary’s function and the genesis of sinovitis respectively.
• The pilus antigens, the protein designated P.2 and the lipo-oligosaccharide are all capable of antigenic variation sufficient to permit repeated reinfection of the same host within a short period.
• Antibodies to the P3 protein do not fix complement and can block bactericidal, complement-fixing antibodies to the lipo-oligosaccharide.
• Strains responsible for disseminated gonococcal infection have been shown to be less susceptible to killing by human serum, are less chemo tactic to neutrophils and elicit greater amounts of blocking antibody.
Clinical Features: 
The risk of contracting gonorrhoea after a single exposure is about 20% for males and probably much higher for females.
• Most men develop symptoms after a 2-5 day incubation period and 90% will experience symptoms within 14 days. 
• Asymptomatic infections are much more frequent in women – up to 80% of infections detected in contacts of symptomatic partners.
• Symptomatic uncomplicated infections in males manifest typically a thick, yellow urethral discharge.
• In females vaginal discharge or dysuria are the major symptoms Accompanying symptoms include a variable degree of mental itching, burning, dysuria, frequency and oedema.
• Infections of the pharynx and rectum (mostly asymptomatic)can result from orogenital and genitoanal sexual contact in males but in females the rectum easily infected by contamination from an infected vaginal discharge.
• Gonococcal infection may present as vulvovaginitis in children infected by sexual abuse or by infected fomites.
Complications:
• Spread of the infection to the epididymis usually unilaterally (20% of patients not receiving antibiotics)
• Acute torsion
• Mumps virus infection; Gram-negative bacilli may be responsible
• Abscess and fistula formation 
• Urethral stricture 
• Infections of the Para urethral glands and Bartholin’s glands
• Gonococcal endometritis (unusual uterine bleeding)
• An acute salphingitis or long-term problems of chronic PID
• Increased risk of ectopic pregnancy
• (Acute salpingitis has to be differentiated clinically from ectopic pregnancy (pregnancy test, ultrasonography) and acute appendicitis (leparoscopy)
• a higher risk of disseminated gonococcal infection (may arise in about 2% of patients with gonorrhoea overall)
  Disseminated gonococcal infection manifests most often as an asymmetric oligoarthritis with a predilection for knees, ankles, and large and small joints of the upper limb.
 Tenosynovitis occurs frequently 
 The skin lesions (classically the tender necrotic pustule, but many other forms also occur)
 Gonococcal arthritis accounts for as much as 20% of acute arthritis in young adults in the tropics.
• Rarer manifestations include endocarditis and meningitis.
• Treatment effective against penicillinase-producing strains may be required.
Ocular gonococcal infection in adults, which is presumed to follow autoinoculation with a contaminated finger in most cases, is a common and potentially blinding complication in developing countries.
It presents as an acute purulent conjunctivitis which may progress rapidly to corneal perforation in the absence of adequate systemic and topical antimicrobial treatment.
The high incidence of infection with N.gonorhoea and C.trachomatis among pregnant women in many tropical countries is reflected in a correspondingly high incidence of ophthalmia neonatarum which occurs in 30-50% of children born to infected mothers if prophylaxis is not administered.
• Usually presents as an acute bilateral purulent conjunctivitis 
• Gonococcal infections can lead to blindness
• Systemic and tropical treatment should be administered to the neonate, and the mother and her sexual partner should also be treated. (Instillation of 1% silver nitrate or 1% tetracycline ointment into the eyes of infants)
When cultures are to be made, the sites for swabbing should be determined by the history and examination findings.
For women the ectocervix should be wiped clean and a swab should be inserted into the cervical region and rotated for 10 seconds.
Rectal swabs are best obtained through a prostoscope. N. Gonorrhoeae is a delicate organism, highly susceptible to drying, and prompt inoculation of media and careful adherence to recommended laboratory technique is important to maximize isolation rates.
• Antigen detection by immunofluorescence or enzyme immunassay, serology, detection of gonococcal DNA.
 Treatment:
• A single dose of supervised oral treatment;
• N. gonorrhoea show both plasmid and chromosomally-mediated resistance to penicillin, tetracycline and co-trimoxazole.
Penicillinase-producing N.gonorrheae account for 30-50% of isolates in many tropical countries.
• New antibiotics: cefriaxone, cefixime, ciprofloxacin 
 (Test of cure 3-5 days after treatment is undertaken where resources permit)
Treatment of contacts should extend to all individuals exposed within 2 weeks of the onset of symptoms in the index case and within 4 weeks of diagnosis of asymptomatic infected individuals.
Prevention 
The major obstacle to the control of gonorrhoea is the large reservoir of asymptomatic or clinically non-specific infections in women and the difficulty of establishing the diagnosis in women.
The development of vaccines for gonorrhoea has been hindered by the antigenic variation manifest by the organism.
Chlamydia Infections
• C. trachomatis is the most prevalent sexually transmitted bacterial pathogen in industrialized countries, and appears to be at least equally prevalent in developing countries 
• C. trachomatis is a Gram-negative bacterium which is an obligate parasite of encaryotic cells
• The genus Chlamydia has a unique life cycle (the inert infectious elementary body has a rigid cell wall). The life cycle is completed when reticulate bodies condense to form elementary bodies, which are released from the inclusion after lyses of the host cell
• The pathological hallmarks of infection with C. trachomatis are: (1)the subepithelial lymphoid follicle; and (2)fibrosis and scarring. The latter may progress for months and years even in the absence of chlamydial organisms demonstrable by conventional means.
Clinical Features 
The clinical spectrum of disease due to chlamydial infection is similar to that seen in gonococcal infection.
• More likely to cause serious sequelae, particularly in women;
• Chlamydial infection causes urethritis
• It is possible that urethral stricture is a late sequelae of chlamydial urethritis
• In females, chlamydial cervicitis is often asymptomatic
• Sometimes patients will complain of vaginal discharge, and the finding of a mucopurulent discharge
• Ascending infection of the female genital tract may lead to endometritis / salpingitis or PID
• Irreversible damage to the fallopian tubes (infertility, ectopic pregnancy)
• Infection can give rise to a perihepatitis with characteristic adhesions between the liver capsule and peritoneum.
• It may give rise to conjunctiva scarring 
• A small proportion of infected infants develop chlamydial pneumonitis
• (between 6 weeks and 3 months of life with a paroxysmal cough and tachypnoea in the absence of fever)
 Rales may be heard on clinical examination 
 A chest radiograph often reveals extensive bilateral pulmonary infiltrates with hyperinflation
Diagnosis 
Several antigen detection tests are now commercially available. 
Antigen detection enzyme immunoassay. 
Swabs from females should be collected from the endocervix and urethra.
A first catch urine specimen appears to be as good as a urethral swab for diagnosing chlamydial infection in males.
Serology is the method of choice for the diagnosis of neonatal chlamidial pneumonia.
Management
C. trachomatis remains sensitive to tetracyclines and erythromycin.
The new macrolide antibiotic azithromycin shows promise as an effective single dose therapy for genital chlamydial infection.
Vaginal Discharge in Women
The three main causes are:
• Candida albicans
• Trichomonas vaginalis and bacterial vaginosis 
• N. gonorrhoeae and C. trachomatis 
A wet preparation, examined with a phase contrast, can usually distinguish between candidiasis, trichomoniasis and bacterial vaginosis.
Candida albicans can be isolated from the vagina of up to 50% of sexually active women, the majority of whom are asymptomatic.
Symptomatic disease is associated with an increase in the number of yeasts present in the vagina. Factors which predispose to this are pregnancy, antimicrobial therapy, oral contraceptive use, immunosuppression and glycosuria.
• The cardinal clinical features of vulvovaginal candidiasis are pruritus vulvae and vaginal discharge.
• The discharge is typically whitish, with curd-like plaques adhering to the vaginal wall, and does not smell.
• There may be erythema or oedema of the vulva and vaginal walls.
• Typical mycelia and yeast cells are seen. 
• The diagnosis can be made on a wet preparation made from the vaginal discharge, the sensitivity of which can be increased by adding 10% potassium hydroxide.
Trichomoniasis 
T. vaginalis has been found in the vagina of up to 30% of antenatal clinic attenders in certain African centres.
• Its prevalence is higher among women with many partners;
• In males most infections are believed to be asymptomatic and self-limiting;
• Occasionally it may give rise to urethritis;
• 75% of women complain of vaginal discharge;
• pruritus vulvae, dyspareumia and dysuria are also common symptoms 
• punctate haemorrhages may be seen on the cervix;
• the diagnosis can be made on a wet preparation collected from the posterior fornix;
• increased numbers of polymorph nuclear leucocytes;
Bacterial Vaginosis 
Bacterial vaginosis is a syndrome in which a malodorous vaginal discharge is associated with characteristic changes in the vaginal bacterial flora.
There is an increase in numbers of anaerobes, Gardnerella vaginalis and Mycoplasma hominis, such that lactobacilli are no longer predominant.
• The discharge is typically homogeneous and white (associated with increased vaginal pH (4.5).
• The characteristic fishy smell is more easily detectable after the addition of a drop of 1% potassium hydroxide to a drop of a discharge on a slide.
• It may be associated with adverse pregnancy outcome (chrioamnionitis).
• The diagnosis depends on the identification of clue cells in a wet preparation of Gram stain made from the vaginal discharge.

Diseases Causing Genital Ulceration 
Chancroid:
Most common cause of genital ulceration in Africa (60%) 
The prevalence is high among commercial sex workers in the cities of Africa.
Chancroid significantly increases the risk of transmission of HIV via heterosexual contact.
Aetiology: It is caused by H. Ducreyi, a small facultative anaerobic Gram-negative bacillus which requires haemic (X factor), reduces nitrate to nitrate and forms typical streptobacillary chains on Gram stain.
Pathogenesis:
Histopathologically, chancroidal ulcers contain three distinct zones: a superficial zone consisting of necrotic tissue, fibrin and numerous bacteria;
An intermediate zone showing oedema and new vessel formation.
A deep zone containing a dense infiltrate of neutrophils and plasma cells with fibroblastic proliferation.
The suppurating lymphadenopathy of chancroid is notable for the large number of neutrophils and small one of bacilli present.
Clinical Features  
• The incubation period – 3-7days 
• A papule appears at the site of inoculation which soon ulcerates.
• The typical ulcer of chancroid is painful and soft, has a purulent base with an undermined edge, and bleeds on contact.
• There is a painful inguinal lymphadenopathy
• Herpes simplex, LAV and donovanosis must also be considered in the differential diagnosis of chancroid.
• HIV-infected individuals may fail to respond to antimicrobial treatment.
Diagnosis:
• Gram stain of smears obtained from ulcers has been advocated in the past
• It depends on the isolation of H. ducreyi from the ulcer
• Swabs taken from the ulcers base + vancomycin
(Plates should be incubated for at least 72 hours in an atmosphere of 5% carbone dioxide at 33C 
• An enzyme immunoassay for the serological diagnosis of chancroid.
Management:
• Keep clean and dry 
• Regular washing in soapy water 
• Antimicrobial treatment: co-trimoxazole, erythromycin (by mouth for 7 days)
• Ciprofloxacin 500 mg daily for three days by mouth;
• Ceftriaxone 500 mg as a single intramuscular dose.

Syphilis 
Seroprevalence surveys have shown high rates of positivity among urban antenatal clinic attenders in many African countries.
Venereal syphilis poses a major threat to the health of neonates in Lusaka, Zambia. The relative rarity of late syphilis in parts of Africa where early syphilis is common has led to speculation that the disease has become more common in recent years. Transmission by sexual contact requires exposure to moist mucosal or cutaneous lesions; experiments in the rabbit suggest that an inoculum of some 50 organisms is sufficient to initiate infection.
Syphilis is caused by T. pallidum one of a small group of treponemas (of the older Spirochaetales) pathogenic to man. It cannot be distinguished in the laboratory from the agents responsible for yaws and pinta (pertenue, T-carateum). It is a spiral organism 6-15/ 4m in length and 0.15/ 4m in width, visible by light microscopy only under conditions of dark-field illumination. 

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