Data Loading...
Microbiology Herpes Viruses Dr. Hani Masaadeh Sharifa ... Flipbook PDF
1 | P a g e Herpes viruses · Herpes viruses in general are classified as large viruses and all of them are DNA viruses.
126 Views
6 Downloads
FLIP PDF 870.36KB
Microbiology Herpes Viruses Dr. Hani Masaadeh
Sharifa Ahmed Mahdi
0|Page
5
NOTE
IT’S MOSTLY MODIFIED SLIDES THE SENTENCES WRITTEN IN RED ARE ILLUSTRATED BY THE DOCTOR.
Herpes viruses ·
Herpes viruses in general are classified as large viruses and all of them are DNA viruses.
I.
Herpes Simplex Virus (HSV)
There are many types of it HSV1 and HSV2 and others. HSV1 and HSV2 infect more than ⅓ of the world’s population, so it’s a common viral infection. HSV1 spread easily and cause sore throat and other manifestations. HSV2 is responsible for the majority of cases of genital herpes, although HSV1 can also lead to genital infections. There are some predisposing factors which triggers this viral infection including: 1. Immunodeficiency 2. High Fever 3. Ultraviolet light 4. Stress → commonly by HSV1 5. Trauma 6. Menstruation → commonly by HSV2 7. Sexual Intercourse → commonly by HSV2 The manifestations are initial episodes are more severe than recurrences. After an incubation period of several days patients notice a prodrome:
1|Page
Itching
Burning
Erythema and vesicles with fluid
The classic vesicles which are painful appear on the: Cervix Rectum Vagina
Perineum
Vulva
Surrounding skin
Diagnosis: o
Clinical diagnosis is made by recognition of multiple, shallow and tender ulcerations or vesicles on or around the genitalia (by naked eye)
o
Laboratory diagnosis:
1. Viral isolation by tissue culture (We use living cells) with a special needle which is the gold standard and it can take up to 5 days with a sensitivity of 70% - 80% only. Then we look for cytopathic effects after 3-5 days. 2. Antigen Detection and Tzanck Tests (Lower sensitivity) 3. Serologic studies Not helpful during the primary illness because of the delay in antibody production (late antibody-antigen reaction), so it can give false negative results. If we could see the antibody we will detect IgM, while in recurrence we will detect IgG and IgM. 4. PCR testing Sensitive (96%) and specific (99%) High cost Limited availability
2|Page
Treatment: Acyclovir binds viral DNA polymerase and ends replication. Medications must be administered early in the course of the illness (Before the 1st or 2nd step of the viral replication to get better results), because HSV replication may end as soon as 48 hours into a recurrence. Only to be used in pregnancy if there is a severe infection by HSV2.
II.
Cytomegalovirus (CMV) Properties:
Belong to the beta-herpesvirus subfamily of herpesviruses. It’s related to genital infections and usually transmitted by sex or mother-to-baby during delivery.
CMV is dsDNA enveloped virus, has a size of around 250-300nm (Large virus), A large number of proteins are present within the nucleocapsid, but the precise number is unknown.
The structure of the genome of CMV is similar to other herpesviruses, consisting of long and short segments which may be orientated in either direction, giving a total of 4 isomers. Nucleocapsid 105nm in diameter and 162 capsomers. Epidemiology:
CMV is one of the most successful human pathogens, it can be transmitted vertically or horizontally usually with little effect on the host. Transmission may occur in utero, perinatally or postnatally. Once infected, the person carries the virus for life which may be activated from time to time, during which infectious virions appear in the urine and the saliva (So the sample which we collect will be urine or saliva, and in the some cases when the virus infect the vaginal area in females we will take vaginal swab). 3|Page
Reactivation can also lead to vertical transmission. It is also possible for people who have experienced primary infection to be reinfecded with another or the same strain of CMV, this reinfection does not differ clinically from reactivation.
Clinical Manifestations: Congenital infection - may result in cytomegalic inclusion disease.
Perinatal infection - usually asymptomatic at the beginning.
Postnatal infection - usually asymptomatic. However, in a minority of cases, the syndrome of infectious mononucleosis may develop which consists of fever, lymphadenopathy, and splenomegaly. The heterophil antibody test is negative although atypical lymphocytes may be found in the blood. Immunocompromised patients such as transplant recipients and AIDS patients are prone to severe CMV disease such as pneumonitis, retinitis, colitis, and encephalopathy.
Reactivation or reinfection with CMV is usually asymptomatic except in immunocompromised patients.
Congenital Infection: It can be defined by the isolation of CMV from the saliva or urine within 3 weeks of birth. We should do tests for the new-born within the 1st three weeks after delivery to treat if present. Commonest congenital viral infection, affects 0.3 - 1% of all live births. The 2nd most common cause of mental handicap after Down's syndrome and is responsible for more cases of congenital damage than rubella.
4|Page
Transmission to the fetus may occur following primary or recurrent CMV infection. 40% chance of transmission to the fetus following a primary infection (High percentage). May be transmitted to the fetus during all stages of pregnancy. No evidence of teratogenecity, damage to the fetus results from destruction of target cells once they are formed (Here they mean that the new-born can acquire CMV from the infected mother). Laboratory Diagnosis: 1. Direct detection: Biopsy specimens may be examined histologically for CMV inclusion antibodies or for the presence of CMV antigens. However, the sensitivity may be low. The pp65 CMV antigenaemia test is now routinely used for the rapid diagnosis of CMV infection in immunocompromised patients.
PCR for CMV-DNA is used in some centers but there may be problems with interpretation.
2. Virus Isolation: Conventional cell culture is regarded as gold standard but requires up to 4 weeks for result: - First we need about 5 days to observe the cytopathic effect (CPE), after that we collect the fluid from the tissue culture and we make centrifugation after Centerfugation we discard the supernatent and keep the sediment then we use ultracentrifugation to collect supernatent (which where virus is present ) and discard the sediments
5|Page
- Finally ,we do enzyme-linked immunosorbent stain for detection of CMV antigens. More useful are rapid culture methods such as the DEAFF test which can provide a result in 24-48 hours. 3. Serology The presence of CMV IgG antibody indicates past infection. The detection of IgM is indicative of primary infection although it may also be found in immunocompromised patients with reactivation, but usually immunocompromised patients lack Igs presence because of the low number of B cells mainly which are the source of the Igs.
We also use ELISA here.
Specimens for Laboratory Diagnosis:
Treatment: Congenital infections - it is not usually possible to detect congenital infection unless the mother has symptoms of primary infection. If so, then the mother should be told of the chances of her baby having cytomegalic inclusion disease and perhaps offered the choice of an abortion. 6|Page
Perinatal and postnatal infection - it is usually not necessary to treat such patients. Immunocompromised patients - it is necessary to make a diagnosis of CMV infection early and give prompt antiviral therapy. Anti-CMV agents in current use are ganciclovir, forscarnet, and cidofovir. III.
Human Papillomavirus (HPV)
- Human Papillomavirus (HPV) is a virus that can cause various disease states including “genital” or “venereal” warts. - Papillomaviruses are a complex group of DNA tumor viruses. They can cause benign growths (papillomas), cancers, or more commonly, transient infections. - HPV infection is causally associated with cervical cancer ; other genital cancers including anal, penile, vulvar, and vaginal cancers may have HPV as co-factor.
HPV Prevalence: - This type is most common as STD. - An estimated sexually active adolescents and young adults 15-24 years of age are infected with genital HPV. - An estimated people infected with genital HPV are infected with multiple types of the virus.
Risk Factors for Acquiring a Genital HPV Infection: - Young age (less than 25 yrs). - Multiple sex partners. - Early age at first intercourse (16 yrs or younger). 7|Page
- Male partner has (or has had) multiple sex partners.
HPV Transmission: - Direct skin-to-skin contact. Usually, but not always sexual contact. In general it’s STD but it can be auto-transmission from area to another in the same person. - Infected birth canal. - Fomites (very rare because the virus is insensitive to dryness).
HPV Incubation: - The average incubation is 3 weeks up to 1 year - Possibly years before appearance of warts or cervical abnormalities - Some will be transient and may never be detected
Common Symptoms of Genital Warts in Males & Females: - The symptoms may include single or multiple fleshy growths around the penis, scrotum, groin, vulva, vagina, anus, and/or urethra. - They may also include as the HSV: itching, bleeding, or burning, and pain. - The symptoms may recur from time to time.
8|Page
There are many complications of Genital Warts if untreated, which include: - It may destroy body tissue around the genitals and anus and may lead to necrosis. In addition, for pregnant women, delivary complications or need for C-section (Caesarean section).
Testing & Treatment for Genital Warts: Can be detected in a clinical exam and the history first. Also, it can be treated by removing the warts if they were clear. The virus cannot be removed, so the warts may grow back.
HPV Diagnostic Techniques: 1) History is very important 2) Visual exam
3) Pap smears to avoid the cancer 4) DNA testing
HPV Treatment Options - Chemical agents (Acidic or basic locally) - Laser surgery - Cryotherapy (Liquid nitrogen) - Imiquimod (Aldara) - Electrosurgery - Defer treatment - Surgical excision - Natural therapies Nowadays we usually use electrosurgery and cryotherapy, before they used to treat by chemicals which can cause burns and this leads to secondary infections and many other complications.
9|Page
Can a person be re-infected with HPV? There appears to be humoral and probably cellular immunity that develops to a specific type of HPV after a person has been infected with it and “has cleared” it. The risk for re-infection with that specific type of HPV appears to be rare. However, a person can be infected with more than one type of HPVs
Molluscum contagiosum is a common, self-limiting, nonscarring, papular, viral skin infection. Groups of papules are found anywhere except palms of hands or soles of feet, containing infectious, white, curd-like material. It’s found mainly in children and young, sexually active adults. Molluscum contagiosum can be transmitted by close contact as the HPV, for example by sport, occupational or sexual. Adult disease is associated with sexually transmitted infections and may be a marker for late-stage HIV infection. Treatment is often unnecessary in children but may prevent further sexual transmission in adults.
Good Luck
10 | P a g e