Common Viruses And Their infections Flashcards
What are the routes of entry of viruses?
- Inhalation: when we take the air inside —> go to the resp sys ( lungs ) ex: influenza
- Ingestion of food and water —> if contaminated —> infect our digestive sys ex: rotavirus
- Inoculation: injections ex: HIV and hepatitis
- Sexual: HIV
- blood transfusion / organ transplantation : ex HIV and CMV
- Congenital or vertical :cross the placenta ex: Rubella, CMV
What are the localized diseases
After the entry into the body, viral infections can be limited in a specific place ( LOCALIZED )
- to the site of inoculation —> skin —> warts
Caused by human papilloma virus - to the body surface —> diarrhea in children —> lead to dehydration
Caused by Rotavirus - To respiratory tract —> Influenza or flu
Caused by Influenza virus A / B / C
What does dissemination mean and how does viruses travel in the body?
- It disperses and goes to different parts of the body —> become generalized infection —> bcz the virus is carried with the blood or the lymphatic system ( carries lymph and fluid with WBCs ) —> go to all parts of the body
- If the infection is blood borne —> viraemia
- Travel in the body by these ways:
A. free ( not inside the cell ) —> in the plasma or the lymph
B. Live inside monocytes or lymphocytes —> ex: HIV kill CH4+ T cells —> which is imp for specific and cellular immunity
C. In nervous sys —> infect the neurons —> ex: rabies
Give examples of generalised/disseminated viral infections:
- Chicken pox:
Caused by varicella zoster virus ( chicken pox virus ) - Measles
Caused by measles virus - Viral haemorrhagic fever (VHF): —> zoonotic viruses transferred from animal reservoirs to humans
Caused by Ebola virus and lassa virus - Rabies:—> zoonotic disease especially dogs ( bite of the infected animal )
Inflammation of the brain —> acute encephalitis
caused by rabies virus
What are the syms of chicken pox
Rash starts on the chest and back —> THEN spread to all parts of the body including:
- Face
- Scalp
- Arms
- Legs
What are the syms of measles
fever
runny nose
cough
rashes all over the body
What are the syms of VHF
bleeding 1. under the skin 2. in internal organs 3. from body orifices A. mouth B.eyes C. ears
Groups of viruses acc to the transmission route
- Enteric viruses
- Respiratory viruses
- Zoonotic viruses
- Sexually transmitted viruses
What are the enteric viruses ?
Fecal-oral route —> Ingestion of fecal-contaminated material
Cause A. inflammation of the stomach and intestine —> gastroenteritis ex: Rotavirus Norovirus Adenovirus Astrovirus ( استر يارباه ادينا نورنا )
B. Systemic disease ex: poliovirus
What are the resp viruses?
• Inhaled, replicate in respiratory tract
- Remain localized in respiratory tract e.g., rhinovirus
- causing systemic diseases e.g.,
A. mumps virus
B. measles virus
Give Examples of resp virus infections?
When I asked him he said that they are all localized
1. Common cold A. Rhinovirus B. Adenovirus ( common btwn gastroenteritis and resp tract ) C. Enterovirus D. Coronavirus
- Flu and flu-like illness
A. Influenza
B. Parainfluenza
C. Resp syncytial virus - Severe acute respiratory infections
A. SARS associated coronavirus
B. MERS associated coronavirus
What are the zoonotic viruses ?
Transmitted from one animal species to another (including
humans)
- Rabies by bats —> dogs —> humans
Not transmitted from humans to other humans - Arboviruses —> arthropod borne viruses —> Arthropods are bugs like mosquitos and insects —> ex. West Nile virus
- Ebola virus and lassa virus causing VHF
What are sexually transmitted viruses ?
• Transmitted during sexual activity
- Many cause lesions in genital tract e.g.,
A. herpes viruses
B. papillomaviruses - Some cause systemic infections e.g.,
A. HIV
B. hepatitis viruses —> ABCDE
What are types of immunity?
A. Specific and cellular mostly by T cells
In cirrhosis,
1. CD8+ T cells kills the virus infected cells which are hepatocytes
2. CD4+ T cells
3. T helper have 2 types: TH1 and TH17 —> secrete proinflammatory molecules known as cytokines
B. Humoral by antibodies
What is cirrhosis ?
It is a consequence of chronic liver disease characterized by replacement of liver tissue by fibrosis, and scar tissue leading to loss of liver function
Killing of the hepatic cells ( killed bcz when it is recognized by the immune system (CD8+ cells and CD4+ cells) and then Thelper cells release inflammatory cytokines —> induce the killing—> then fibrosis —> scar and the replacement by fibrosis
Bilirubin in normal people is metabolized in the liver and goes to the stool
But in these patients —> it is not metabolized so it goes to the blood —> go to skin and urine and eyes—> jaundice
What causes conjunctivitis / keratitis / uveitis?
They are Ocular viral infection caused by
Adenovirus ( also in common cold and gastroenteritis )
Herpes simplex virus (ocular herpes)
Enterovirus
What is the conjunctiva?
Thick transparent mucous membrane that covers the eye ball
What is cornea?
Front part of eyeball through which light waves pass
What is uvea?
The middle layer of the eye. It lies beneath the white part of the eye (the sclera). It is made of the iris, ciliary body, and choroid.
What are the viral infections of CNS ?
- Meningitis
- Encephalitis
- Meningoencephalitis
- Rabies
- poliomyelitis
- Acute disseminated encephalomyelitis ADEM
What is meningitis and what causes it?
inflammation of the protective membranes
(meninges) surrounding the brain and spinal cord
- Enteroviruses
- Herpesviruses
- Mumps virus
Where as in ocular:
- entero
- herpes
- adeno
What is encephalitis and meningoencephalitis and what causes it?
Encephalitis: Inflammation of the brain
Meningocephalitis: inflammation of the brain and the surrounding membranes
Caused by:
- Herpesvirus (HSV-1, HSV-2, CMV, EBV, HHV-6)
- Arboviruses (west Nile / Japanese encephalitis )
- Rabies
What is A cute Disseminated Encephalomyelitis (ADEM)?
inflammation of the brain and spinal cord.
- Measles virus
- Herpesviruses (EBV, HSV, CMV, VZV)
- Mumps virus
- Rubella virus
What are the viruses that cause skin rashes ?
- Chicken pox
- Varicella-zoster virus
- Measles
- Rubella
- HHV6 and HHV7
- parvovirus B19
- Small pox
What are the characteristics of shingles or zoster caused by VZV?
painful skin rash with blisters in a localized area
What causes warts, skin cancer and cervix cancer
Human papilloma virus
- Verruca vulgarisms —> palm of the hand
- Verruca plantaris —> sole of the foot
- Squamous cell carcinoma
- Cervical carcinoma
What are oral lesions and what causes it?
Inflammation of the gums and mouth
Herpes Simplex virus (HSV)
- Gingivostomatitis: inflammation of the oral mucosa and gingiva causing sores on the inside of the cheeks or gums
- Fever blister/Cold sore: fluid filled painful blister on or around the lips
What is AIDS?
Caused by HIV
Characterized by signs of severe immune deficiency:
- Rapid weight loss
- Recurring fever or profuse night sweats
- Extreme and unexplained tiredness
- Prolonged swelling of the lymph glands in the armpits, groin, or neck
- Prolonged diarrhea that lasts for more than a week
- Sores of the mouth, anus, or genitals
- Pneumonia
What are the effects of infection with HIV?
- Affects WBC that fight infection in healthy people
- Changes the composition of WBC and enables HIV to replicate itself
- Weakens the immune system
- ⬆️ vulnerability of life-threatening illnesses : other infections or cancers
What are the main route sod HIV transmission ?
- Sexual : main mode —> 70-80%
- Parenteral:
A. Blood transfusion
B. Contaminated needle pricks
C. needle sharing - Vertical ( perinatal )in uterine during labor and delivery and breast feeding
