Dr. Sabitha Vijayan BHMS, MD
Interferon – antiviral substances, it is a family of host coded proteins produced by cells on induction by viral or non viral substances
Pox virus:- small pox- last detected case of small pox – sarban devi , a bengladeshi woman on 24th may 1975.
- Herpes simplex virus type I causes oral and cutaneous lesions spreading by direct contact
- Herpes simplex type II causes genital tract infection transmitted venerally.
- Occupational variety of cuteneous lesion is herpetic whitlow seen in doctors, nurses and dentists.
Generalized eruption occurs in children suffering from eczema
Crops of vesicles appear around the ulcer;clinically indistinguishable from vaccinia virus infections . both designated as Kaposi’s varicella form eruptions.
In chicken pox eruptions are centrifugal in distribution. (small pox rashes are centripetal in distribution)
In chicken pox patients , secondary bacterial infection due to streptococci or staphylococci occurs. This is called Reyes syndrome. Clinically characterized by acute hepatic failure, encephalopathy and hypoglycemia.
Herpes zoster (syn; shingles, zona)
- Occurs in patients affected with chicken pox years later.
- Ramsay hunt syndrome:- rare form of zoster affecting facial nerve with eruption on areas of tympanic membrane and external auditory canal with facial palsy.
Epstein – Barr virus
Causes IMN (infectious mono nucleosis)
- Burkitt’s lymphoma
- Naso pharyngeal carcinoma
IMN (glandular fever) – acute self limited illness seen in non immune adults following primary infection with EB virus. Incubation period is 4- 8 weeks . standard diagnostic test is Paul – Bunnel test
Adenovirus causes respiratory infection , usually picorno virus includes
– enterovirus – coxachie virus and polio virus
Poliomyelitis is mainly 3 types
- Minor illness :- called abortive polio with head ache, sore throat, and malaise
- Non paralytic illness:- it does not progress beyond asceptic meningitis
- 5-10% causes paralytic polio
Vaccine:- 2 types
a. Salk’s killed polio vaccine
b. Live polio vaccine is oral polio vaccine
- Orthomyxovirus causes influenza.
- Paramyxovirus Eg. Mumps virus
- Measles (Rubiola) – genus morbiliform virus
- Multinucleated giant cells called Warthin – Finkelclay cells are found in lymphoid tissue of patients.
- Koplik’s spots developon buccal mucosa two or three days before the appearance of rash.
- Japanese encephalitis (vector- culex tritaneorynchus)
- Yellow fever – Vector – Aedes aegypti
- Dengue fever – Vector – Aedes aegypti
Tick borne encephalitis eg. KFD (Kyansur forest disease)
Eg. Rabies virus causes hydrophobia
- Diagnosis is confirmed by negri bodies (inclusion bodies) in brain in post mortem examination mostly in hippocampus and cerebellum
- PAPOVA virus include papilloma virus group and polyoma virus group.
- The common human disease produced by papova virus is papilloma or wart. (verruca vulgaris)
- A special type of wart is condylom accuminatum or genital wart found on external genitalia. This may be transmitted venerally and may occasionally turn malignant.
- Parvo virus cause erythema infectiosum –‘the fifth disease’ a contagious disease of children characterized by erythematous rash first appearing on cheeks. – slapped cheek appearance.
RUBELLA OR GERMAN MEASLES
- Caused by genus rubivirus of family toga viridae
- Koplik’s spot absent
- Rash is discrete and coalesce and disappear on 3rd day
- Non tender enlargement of post cervical glands is characteristic
- If Rubella occurs in early pregnancy, the foetus may die
- Congenital malformations are common during first trimester.
- Infected babies constitute an important source of infection for about 6 months (virus may persist for years in tissues such as cataractous lenses)
- Diagnosis of Rubella in early pregnancy is an indication for therapeutic abortion.
- Cruzfelt – Jacob disease is sub acute encephalopathy with progressive incoordination and dementia caused by group b prion virus.
Haemorrhagic fever with renal syndrome(HFRS)- also known as epidemic haemorrhagic nephrosonephritis is caused by Huntaan virus of family Bunya viridae.
HIV – human immunodeficiency virus – retro virus now called Human T cell lymphotrophic virus
- RNA virus attacks CD4 cells.
- A. Envelops antigens – 1. spicks antigen, 2. transmembrane
- B. Shell antigen
- C. Core antigen
- D. Polymerase antigen
Incubation period varies from 2-6 weeks to 15 years.
Features characaterising AIDS
- 1. Lymphopenia
- 2. Selective T cell deficiency – reduction in numbers of T4 (CD4) cells, inversion of T4: T8 ratio
- 3. Decreased delayed hypersensitivityon skin testing
- 4. Hypergammaglobulinaemia – predominantly IgG and Ig A; also IgM in children.
- 5. Polyclonal activation of B cells an dincreased spontaneous spontaneous secretion Ig.
- Common malignancies associated with HIV infection is Kaposi’s sarcoma and lymphoma- hodgkin’s and Non hodgkin’s types.
HIV- Elisa for detection : Western blot for confirmation
Ergotoxicosis (ergotism) is due to claviceps purpura growing on fruiting heads of rye.
Hepatitis A – incubation period – 2- 6 weeks
Hepatitis B – I P 4 – 8 weeks
Hepatitis C – I P 2 – 22 weeks
Hepatitis D I p 4 – 8 weeks
Hepatitis E I P 2 – 9 weeks
- Hepatitis B – DNA virus ; all others are RNA virus
- Spreads by faeco oral route – hepatitis A and E
- Spreads by percutaneous route – Hepatitis B,C and D
- Hepatitis B also spread by vertical and sexual route
- Oncogenicity present in Hepatitis B especially after neonatal infection.
- Carrier state present in Hepatitis B only
- Hepatitis B virus may present in blood and other body fluids and excretions such as saliva, breast milk,semen, vaginal secretions, urine , bile etc.
- Feces not known to be infectious
- HBs Ag is the first viral marker to appear in blood after infection; it remains in circulation throughout icteric course of disease. In a typical case it disappear within roughly 2 months but may last for 6 months.
- HBsAg is not demonstrable in circulation but antibody, antiHBe appear in serum a week or two after appearance of HbSAg
- So anti-HbeAg is the antibody marker to be seen in blood.
- HBeAg (HB envelop antigen) appears in blood concurrently with HBsAg. HbeAg is an indicator of intrahepatic viral replication and its presence in blood indicates high infectivity.
- For diagnosis of HBV infection, simultaneous presence of IgM, HBC indicates recent infection and presence of IgG ;anti H-Be indicates remote infection.
- Type E hepatitis : enterically transmitted.
- Non A – non B hepatitis caused by Hep. C virus
Inclusion body inviruses
Guarnieri body – Varicella, Vaccinia
Negri body – Rabies
Henderson – Paterson body – Molluscum contagium
- b. Intranuclear
- a. Lipschutz bodies – herpes fibrilis, herpes zoster, varicella
- b. Councilmann’s bodies – yellow fever, virus B encephalitis
- c. Nicolau’s bodies – herpes fibrilis, herpes zoster , polio, Rift valley fever
Association of virus with human cancer
|Virus family||Virus genus||Human cancer|
|Herpes virus||E-b Virus||Nasopharyngeal carcinomaAfrican Burkitt’s lymphomaB- cell lymphoma|
|Herpes 2 virus||Cervical carcinoma|
|Papova viridae||Papilloma virus||Urogenital tumourSquamous cell carcinoma|
|Hepadne virus||Hep B virus||Primary Hepatocellular carcinoma|
|Retrovirus||HTL virus||Adult T Cell Leukaemia|
Viral infections associated with associated with maculopapular rash
- Adenovirus infection
- Arbovirus infection
- Cytomegalovirus infections
- Hep-B virus
- IMN (kissing disease)
- Haemolytic uraemic syndrome caused by virotoxin producing e-coli
- Brazilian purpuric fever caused by Haemphilus aegypticus
- Cryptospridum causes diarrhea
- Cat scratch disease is caused by cat scratch bacillus
Superficial mycosis(cutaneous ) or dematophytis
- Microsporum – attacks skin and hair ; not nail
- Tricophyton attacks skin , hair and nails. Most important human parasites are T. rubrum and T. tonsuran
- Epidermophyton – e.floccosum attacks skin and nails but not hair.
- Tinea capitis – ring worm of scalp
- Tinea circinata – ringworm of glabrous skin
- Tinea barbae – ringworm of beard
- Tinea pedis – Athletes foot
- Tinea cruris – Dhobi itch or Jock itch
- Tinea unguum – ring worm of nails
- Candid albicans – yeast like fungi
- Histoplasma capsulatum – Darling’s disease
- Cryptococcus neoformans – yeast
- Aspergillus – fungus ball
- Cocciodes immitis – desert rheumatism
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