Onfectious Disease Part 2 Flashcards
Transient infections
Measles Mumps Polio virus West Nile virus Viral hemorrhagic fever
Is a leading cause of vaccine preventable death and illness worldwide
Measles or rubeola virus
Measles is transmitted by
Respiratory droplets
Transient infections
Measles
Cell surface receptors for the virus
All nucleated cells
CD46
Transient infections
Measles
Cell surface receptors for the virus
Cells of immune system
SLAM or
CD150
Transient infections
Measles
Cell surface receptors for the virus
Epithelial cells
Nectin 4
Measles pathogenesis
Both CD46 and SLAM bind the
Viral hemagglutinin protein
Measles pathogenesis
Viral entry Multiply in upper respiratory epithelial Lymphoid tissues Replicate. In lymphatics Blood and systemic dissemination
Measles dissemination to many tissues
Conjunctiva Respiratory tract Urinary tract Small blood vessels Lymphatic system CNS
Measles with T cell mediated immunity
Rash
Measles with malnourished children
Croup
Pneumonia
Diarrhea
Keratitis
Black measles
Measles with Ab mediated immunity
Protects against reinfection
Measles can cause transient but profound immuno suppression
Secondary bacterial and viral infection
Measles
Vasodilation of skin vessels, edema, and moderate non specific mononuclear peri vascular infiltrate
Blotchy, reddish brown RASH
Measles
Ulcerated mucosal lesions in oral cavity near opening of stensen ducts marked by necrosis, neutrophils exudate and neurovascularization
Koplik spots
Measles
Follicular hyperplasia of lymphoid organs with multinucleated giant cells
Warthin- finkeldey cells
Measles
Peri bronchial and intestinal mononuclear cell infiltration
Measles pneumonia
Mumps
Characteristics
Mumps virus a member of paramyxovirus just like measles
Mumps
Two types of surface glycoproteins
Hemagglutinin and neuramidase activity
Cell fushion and hemolytic activity
Mumps
Pathogenesis
Inhalation of respiratory droplets URT Draining lymphnodes Activated T cells Blood Salivary glands and other sites (CNS, testis,ovary and pancreas)
Mumps
Desquamate on of cells, edema, and inflammation
Infects salivary gland ductal epithelial cells
Mumps
Most common extra salivary gland complication
Aseptic meningitis
Mumps
70% bilateral
Salivary glands are enlarged with doughy consistency, moist, glistening and reddish brown on cross section
Memos parotitis
Mumps parotitis
Microscopic
Edematous gland interstitium
Diffuses infiltration by macrophages, lymphocytes and plasma cells
Compress acini and ducts
Mumps
Testicular swelling due to edema, mononuclear cell infiltration, and focal hemorrhages
Mumps orchid is
Mumps or hits pathogenesis
Parenchymal swelling
Compromise blood supply
Positive areas of infarction
Mumps
Sterility due to
Scars and atrophy of the testis after resolution of infection
Mumps
Parenchymal and fat necrosis with neutrophil rich inflammation
Pancreas
Mumps
Peri venous demyelination and perivascular mononuclear cuffing
Mumps encephalitis
A spherical, unencapsulated RNA virus of the entero virus genus
Poliovirus
Poliovirus
There are 3 major strains of polio virus included in the
Stalk formalin-fixed (killed) vaccine
Sabin oral, attenuated (live) vaccine
Poliovirus
Causes poliomyelitis or inflammation of gray spinal cord also known as
Infantile paralysis
Poliovirus
Pathogenesis
Fecal oral route Oropharynx Secreted in saliva Swallowed Multiply in lining of mucosa Viremimotor neuron of spinal cord or brain stem
Poliovirus
Species specificity determined by amino acid residues that are present in the
Human receptor
CD 155
Epithelial adhesion molecule
Poliovirus
Replicates in
Motor neurons of the spinal cord (spinal poliomyelitis) Brain stem ( bulbar poliomyelitis)
Poliovirus
Rare cases of poliomyelitis that occur after vaccination are caused by
Mutations of the attenuated viruses to wild type forms
Poliovirus
Microscopic
Neuronophagia
West Nile virus
Arthropod borne virus (arbovirus) of the flavivirus froup
West Nile virus
Accidental host
Human
West Nile virus
Transmission
Mosquitoes to bird or mammals
Developed prolonged viremia (major reservoir for the virus)
West Nile virus
Pathogenesis
Mosquito bites Dendritic cells Lymphnodes Blood stream BBB Infects neurons
West Nile virus
Essential host factor that resist neuro invasive infection
Chemokine receptor CCR5
West Nile virus
Associated with symptomatic and lethal WNV infection (protective against HIV-1 infection
CCR5 32 allele
West Nile virus
Microscopic
Encephalitis
Viral hemorrhagic fevers
Systemic infectious caused by enveloped RNA viruses in four different genera
Arenaviridae
Filoviridae
Bunyaviridae
Flaviviridae
Viral hemorrhagic fevers
Hemorrhagic manifestations due to
Thombocytopenia or severe platelet or endothelial dysfunction
Viral hemorrhagic fevers
Increased vascular permeability
Necrosis and hemorrhage in organs,
hepatocellular necrosis
Viral hemorrhagic fevers
Infection stimulates cytokine release
Contribute to severe cytophatic effects or DIC
Chronic latent infections (herpesvirus infections)
Herpes simplex virus
Varicella zoster virus
Cytomegalovirus
Chronic latent infections
The persistence of viral genomes in cells that do not produce infectious virus
Latency
Herpes viruses
Large
Encapsulated
Ds DNA genome
Non infectious form with periodic reactivation and shedding of infectious virus
Herpes virus
Three subgroups of herpesviruses
Alpha group viruses
Herpes simplex virus 1&2
Varicella zoster virus
Three subgroups of herpesviruses
Lhymphotropic beta group viruses
CMV or HHV5
HHV6
HHV7
Three subgroups of herpesviruses
Infect and produce latent infection in a variety of cell types
Lymphotropic beta group viruses
Three subgroups of herpesviruses
Gamma group viruses
EBV
HHV-8/KSHV (karposi sarcoma)
Three subgroups of herpesviruses
Latent infection mainly in lymphoid cells
Gamma group viruses
Produce acute and latent infection
Replicate in skin and mucous membranes at the site of entrance of the virus (Oropharynx or genitals)
HSV 1 and 2
HSV 2 infection increases the risk of HIV transmission by
Four fold
HSV2 increases the risk of HIV acquisition by
Two to three fold
HSV2
Negative keratitis
Negative encephalitis in adult
70%neonatal infection
Transmission is primarily genital
HSV1
Urogenital infections 10-30% Positive kaperatitis Positive encephalitis adult Neonatal infection 30% Transmission primarily non genital
HSV infected cells contain large, pink to purple intranuclear inclusions
Cowdry type A
Herpes simplex virus
Due to ballooning degeneration of epidermal cells and intracellular edema
Fever blisters
Cold sores
Herpes simplex virus
HSV1
Seen in children
Vesicles extending to retro pharynx with cervical LAD
Gingivostomatitis
Herpes simplex virus
HSV1
Swollen, erythematous lesions of the fingers or palm
Infant and health care workers
Herpetic whitlow
Herpes simplex virus
HSV1 and HSV2
Vesicles on the genital mucous membranes and external genitalia rapidly converted to superficial ulcerations
Can be transmitted to neonates during passage of birth canal
Genital herpes
Herpes simplex virus
Temporal lobes are the principle target
Hemorrhagic necrosis
Herpes encephalitis
Herpes simplex virus
Diagnisis
Tzanck smear
Herpes simplex virus
Diagnosis
Rapid result but cannot distinguish between HSV and VZV
Electron microscopy of vesicle fluid
Herpes simplex virus
Diagnosis
Can distinguish between HSV andVZV
Immunofluorescnence of skin scrapping
Herpes simplex virus
Diagnosis
Now used routinely for the diagnosis of herpes simple encephalitis
PCR
Herpes simplex virus
Diagnosis
HSV1&2 are among the easiest to cultivate. It usually takes only 1-5 days for a result to be available
Virus isolation
Herpes simplex virus
Diagnosis
Used to document the recent infection. Not useful in acute phase
Serology
Varicella-Zoster Virus
Acute infection
Chickenpox
Varicella-Zoster Virus
Reactivation of latent
Shingles(herpes zoster)
Varicella-Zoster Virus
Spread by
Respiratory aerosols
Varicella-Zoster Virus
Like HSV
Infects mucous membrane
Evades immune response and establishes latency in sensory ganglia
Varicella-Zoster Virus
Unlike HSV
Aerosols
Hematogenously
Widespread vascular lesions
Varicella-Zoster Virus
Chickenpox
Rash occurs approximately
2 weeks after respiratory infection
Varicella-Zoster Virus
Chickenpox
Lesions
Multiple
Centrifugally
Dew drop on a rose petal like HSV
Varicella-Zoster Virus
Shingles
Occurs when
Latent VZV in the dorsal root ganglia is reactivated and infects sensory nerves that carry it to one or more dermatomes
Varicella-Zoster Virus
Shingles
Lesions
Intense itching
Burning
Sharp pain
Because of radiculoneuritis
Varicella-Zoster Virus
Shingles
Geniculate nucleus may be involved causing facial paralysis
Ramsay hunt syndrome
Cytomegalovirus
Latently infects monocytes and their BM progenitors and can be reactivate when
Cellular immunity is depressed
Cytomegalovirus
Cause asymptomatic or mononucleosis like infection in healthy individual but
Devastating in neonates and immunocompromised patients
Cytomegalovirus
Virus is spread in most secretions, particularly
Saliva
Urine
Vaginal secretions
Semen
Cytomegalovirus
Most common opportunistic viral pathogen in
AIDS
Cytomegalovirus
Modes of transmission
Transplacental
Neonatal transmission via cervical or vaginal
Transmission via saliva
Latrogenic transmission
Cytomegalovirus
Can infect dendritic cells and impair antigen processing and the ability of dendritic cells to stimulate
T lymphocytes
Cytomegalovirus
Eludes immune response by
Down modulating MHC 1&2
Producing homologous of TNF receptor
Activate and evade NK cells
Cytomegalovirus
Produce enlargement of infected cells
Cytomegaly
Cytomegalovirus
Large inclusion body within the nucleus surrounded by clear hale
Owl’s eye
Cytomegalovirus
Cytomegalic inclusion disease
Congenital infections
Cytomegalovirus
Infection acquired during passage through the birth canal or from breast milk
Perinatal infection
Cytomegalovirus
Fever, atypical lymphocytes
Lymphadenopathy
Hepatitis
Cytomegalovirus mononucleosis
Hepatitis B virus
Member of the
Hepadnavirus family
Hepatitis B virus
A DNA virus transmitted percutaneously
Sexually
Perinatally
Hepatitis B virus
A etiologic agent of
Serum hepatitis
Includes viruses implicated in the causation of human cancer
EBV
HOV
HBVC
HTLV1
Epstein Barr virus
Also known as
Human herpes virus 4
Member of herpes virus family
Epstein Barr virus
Transmitted by
Close human contact, frequently with saliva during kissing
Epstein Barr virus
Benign, appearance of atypical T lymphocytes in blood (mononucleosis cells)
Infectious mononucleosis
Epstein Barr virus
Associated with developmant of
Hairy leukoplakia
Burkitt lymphoma
Nasopharyngeal carcinoma
Epstein Barr virus
Infects cell types that express the receptor for complement C3d component_______ certain _______ and ________
CR2
CD21
Epithelial cells
B lymphocytes
Epstein Barr virus
Binds EB genome to host cell chromosome
EBNA1
Epstein Barr virus
Drives B cell activation and proliferation
LMP1
Epstein Barr virus
Promotes B cell activation and replication
EBNA2
Epstein Barr virus
Inhibits macrophages and DCs and suppress antiviral T cell responses
Produce homologue of IL-10
Epstein Barr virus
Pathogenesis
Activated B cells disseminate in the circulation secrete antibodies with several specificities
Heterophile anti sheep red blood cell
Epstein Barr virus
Atypical lymphocytes
CD8 + CTLs and
CD16 + natural killer cells
Epstein Barr virus
Reactive proliferation of T cells largely centered in lymphoid tissues
LAD
Splenomegaly
Epstein Barr virus
Diagnosis depends on
Lymphocytosis
Monospot test ( + heterophile antibody)
Specific antibodies for EB antigens
Four types of viral infection
Acute or transient infections
Chronic latent infections
Chronic productive infections
Transforming infections