This document discusses slow virus diseases, which are infections characterized by very long incubation periods, slow but relentless courses, and fatal outcomes. It describes several examples of slow virus diseases in humans and animals caused by viruses from families including retroviruses, paramyxoviruses, togaviruses, polyomaviruses, and prions. These diseases have long latency periods ranging from months to decades before symptoms appear. They progressively affect the central nervous system and have no effective treatment or immune response, inevitably leading to death.

1. SLOW VIRUS DISEASES
Dr Vishal Kulkarni
MBBS MD (Microbiology)

2. Introduction
 The term “slow virus disease” applied to group of
infections in animals & humans characterized by
a very
- Long incubation period.
- Slow but relentless course
- Terminating fatally
 Concept was proposed by Singurdsson- a
veterinary pathologist

3. Characteristics-
 Incubation period ranging from months to years
 Course of illness lasting from months to years
with remission & exacerbations
 Predilection for involvment of CNS
 Absence of immune response
 OR immune response that may actually
contribute to pathogenesis
 Genetic predisposition
 Invariable fatal termination

4. Virus Virus Family Disease
Typical
Latency
Epidemiology
JC Virus
Polyomavirus
Progressive
multifocal
leukoencephalopa
thy
Years to Life§
Unknown;
Contaminated
water?
BK Virus Polyomavirus BK Nephropathy Years to Life§
Unknown;
respiratory
spread/urine?
Rubeola
(Measles)
Paramyxovirus
Subacute
Sclerosing
Panencephalitis
1-10 Years
Respiratory
droplets
Rubella Togaviridae
Progressive
Rubella
Panencephalitis
10-20 Years
Respiratory
droplets
HIV Retrovirus AIDS 5-10 Years
Infected blood
or other body
fluids

5. Virus Virus Family Disease
Typical
Latency
Epidemiology
HTLV 1 Retrovirus
Adult T-cell
Leukemia/Lymp
homa
10-30 Years
Infected blood
or other body
fluids
HTLV 2 Retrovirus
Atypical Hairy
Cell Leukemia
10-30 Years
Infected blood
or other body
fluids

6. Classification
 Group A-
 Slowly progressive infections of sheep
 Visna
 Maedi
 Caused by serologically related non-oncogenic retro-
viruses called as lentiviruses
 Another e.g.- HIV
 Group B-
 Comprising prion disease of CNS, scrapie,mink
encephalopathy, kuru, CJD.

7.  Are collectively known as subacute spongioform viral
encephalopathy
Group C-
- Consisting two unrelated CNS diseases of human
beings
- Subacute sclerosing panencephalitis and
- Progressive multifocal encephalopathy

8. Group A diseases
Visna
- Demyelinating disease of sheep
- Characterised by paresis, paralysis & death
- It was eradicated by slaughtering of all infected
animals in 1957
Maedi
- It is slowly progressive haemorrhagic pneumonia of
sheep

9. Group B Diseases
Infections in animals-
- Scrapie
- Mink encephalopathy
- Bovine spongioform encephalopathy (mad cow
disease)
Infections in humans
- Creutzfeldt-Jakob disease (CJD)
- Kuru

10. Pathology
 Infective agent is proteinaceous in nature
 Devoid of DNA & RNA, known as prions
 It is usually resistant to physical & chemical
agents
 Can be transmitted to animals by oral or
parenteral challenge
 PrP  PrPSC
Stanley B. Prusiner

11. Proliferation of abnormal protein PrPSC.
Its accumulation in CNS disrupts
architecture & function of brain

13.  Creutzfeldt-Jacob disease
 is a subacute encephalopathy characterized by
 Progressive inco-ordination, dementia & fatal termination.
 Two forms
 Gerstamann-Straussler- Scheinker’s syndrome
 Fatal familial insomnia
 can occur after
 corneal transplant
 contaminated injection of pitutary growth hormone
 Cadaveric human dura grafts used in head injury

14.  A varient of CJD that affected young people (<45
years) in Britain in 1996
 Raised fear of infection through eating BSE
infected beef

15. Kuru
- Characterised by
- progressive cerebellar ataxia,
tremers
- Terminates fatally in 3-6 months
- IP- 5-10 years
- Infections believed to be due to cannibalism &
Sorcery
- A tribal custom of eating dead bodies of relatives after
ritual non sterilising cooking

17. Group C Diseases
Subacute sclerosing pan encephalitis ( SSPE)
- Delayed sequel of measles viral infection
- Progressive deterioration of mental & motor function
- Brain cells shows evidence of measles virus infection
- Strains isolated are defective

18. - May also develop as very late complication live
measles virus vaccination
- Ab in serum & CSF is characteristic
- Rare complication of Rubella virus infection

19.  Progressive multifocal leucoencephalopathy
 is a rare demyelinating disease in elderly persons
 Whose immune response is impaired by
immunosuppression & malignancy
 Deterioration of motor function, vision & speech
 Polyoma virus has been demonstrated by electron
microscopy in brain biopsy of patients.

21. THANK YOU…