Presentation on theme: "In the name of Allah, Most Gracious, Most Merciful"— Presentation transcript:
1 In the name of Allah, Most Gracious, Most Merciful M. A. El-Farrash
2 Virology of Pharyngitis, Gastroenteritis and Meningitis Prof Virology of Pharyngitis, Gastroenteritis and Meningitis Prof. Mohamed El-Farrash 2015
3 PharyngitisPharyngitis “not tonsillitis” is the most common cause of a sore throat.Like many types of inflammation, pharyngitis can be Acute “characterized by a rapid onset and typically a relatively short course” or Chronic (relatively long course with milder clinical form).M. A. El-Farrash
4 Acute PharyngitisMost (40–80%) acute cases of pharyngitis are caused by viral infections.The remainder (20 – 60 %) are caused by bacterial infections, fungal infections, or irritants as pollutants or chemical substances. M. A. El-Farrash
5 Viral and Bacterial Pharyngitis M. A. El-Farrash
6 Viral Pharyngitis Adenovirus is the most common of the viral causes. Pharyngitis can be a feature of many different types of viral infections.Adenovirus is the most common of the viral causes.In Adenoviral pharyngitis the degree of neck lymphadenitis is modest and the throat often does not appear red, although it is very painful.M. A. El-Farrash
7 Adenoviruses Morphology Icosahedral,non-envelopedvirus containingdouble strandedlinear DNA genome.Human adenoviruses are classified into 6 subgroups (A – F) containing 56 serotypes.M. A. El-Farrash
8 Adenoviruses Pathogenesis Infections by adenoviruses are very common.Most infections are asymptomatic.Virus was isolated from tonsils/adenoids surgically removed, indicating latent infections.It is transmitted by droplet, contact or feco-oral.Adenovirus infections are difficult to distinguish from Influenza, Parainfluenza or RSV.M. A. El-Farrash
9 Adenoviruses Pathogenesis Adenoviruses can cause:Acute febrile pharyngitis and pneumoniaConjunctivitis and keratoconjuctivitispharyngo-conjunctival feverGastroenteritis and intussusceptions in infantsAcute hemorrhagic cystitisSever pneumonia in AIDS patients.M. A. El-Farrash
10 Diagnosis and Treatment Laboratory diagnosis is done by:Virus isolation by culture on human fibroblasts and founding the CPE (rounding, clustering and swelling)PCR for DNA detectionAntibody detection by CF, NT and HI tests.Management: No specific antiviral agents and no vaccine.M. A. El-Farrash
12 Human Herpes Viruses Structure: Eight human herpes virus species are known.All have the ability to enter a latent state following primary infection and to be reactivated at a later time.Structure:Capsid: Icosahedral.Genome: Double stranded, linear DNA.Envelope: With glycoprotein spikes.M. A. El-Farrash
14 Epstein-Barr virus (EBV) The Epstein-Barr virus (EBV) or Human herpes virus 4 (HHV-4) is one of the most common viruses in humans (more than 70% seropositivity).EBV has a dual cell tropism for human B-lymphocytes and epithelial cells.EBV often causes asymptomatic infection but may cause infectious mononucleosis in few cases.M. A. El-Farrash
15 Infectious Mononucleosis Also known as glandular fever, or Mono.Transmission occurs from exchanging saliva (Kissing disease) and also by airborne infection.It is associated with the appearance of unusually large lymphocytes (atypical lymphocytes) in blood.Symptoms are fever, general malaise, sore throat and generalized lymphadenitis.M. A. El-Farrash
16 EBV-associated malignancies Burkitt's lymphoma is a type of Non-Hodgkin's lymphoma most common in equatorial Africa and co-exists with the presence of malaria.Malaria infection causes reduced immune surveillance of EBV immortalized B cells, so allowing their proliferation.Burkitt's lymphoma commonly affects the jaw bone, forming a huge tumor mass.M. A. El-Farrash
18 Nasopharyngeal carcinoma It is found predominantly in Southern China and Africa, due to genetic and environmental factors.It is more common in people of Chinese ancestry (genetic), and is also linked to Chinese diet (high amount of smoked fish, which contain nitrosamines) a well known carcinogens.M. A. El-Farrash
20 EBV Laboratory Diagnosis Blood film: lymphocytosis and many abnormal lymphocytes.Detection of EBV in lymphocytes by PCR.Paul-Bunnel test: It is non specific test in which we add serum of the patient + sheep RBCs agglutination of RBCs (positive).Detection of specific antibodies to viral antigens.Virus isolation from saliva.M. A. El-Farrash
22 Myxoviruses Name is from the Greek 'myxo' = mucus. The first isolated and known member of the group was Influenza virus.The group has 2 families:Orthomyxoviridae: which contains the influenza viruses and other non human viruses.Paramyxoviridae: containing the parainfluenza, mumps, measles and respiratory syncytium virus.M. A. El-Farrash
23 Myxoviruses Orthomyxoviridae: Paramyxoviridae: Particle size: nm (highly pleomorphic)Core diameter: 9 nm.Genome: Segmented (-) sense RNA.Replication: Nuclear.Paramyxoviridae:Particle size: nm (somewhat pleomorphic)Core diameter: nm.Genome: Non-segmented (-) sense RNA.Replication: Cytoplasmic.M. A. El-Farrash
24 Influenza VirusInfluenza virus belongs to Orthomyxoviridae family (s/s, negative-sense RNA viruses).The particles are mostly spherical.The virus has a lipid envelope from which project prominent glycoprotein spikes of two types:1. Haemagglutinin (HA or H),2. Neuraminidase (NA or N).The genome is composed of 8 segments (7 in type B).M. A. El-Farrash
26 Virus MutationEvery now and then ( years) a major new pandemic strain appears in man, with a totally new H and sometimes a new N as well (Antigenic Shift).This new variant may cause a major epidemic around the world.Over the subsequent years this strain undergoes minor changes (Antigenic Drift) every two to three years.M. A. El-Farrash
27 SerotypesThere are 16 known (H) serotypes and 9 known (N) types of Influenza A virus giving a large number of subtypes due to different associations.Fifteen subtypes of influenza A virus are known to infect birds, thus providing a reservoir of influenza viruses circulating in bird populations.M. A. El-Farrash
29 InfluenzaInfluenza is characterized by fever, myalgia, headache and pharyngitis.There is usually no coryza (runny nose) which characterizes common cold infections.Symptoms may be very mild, (even asymptomatic) moderate or very severe.Spread: rapid via aerial droplets with inhalation into the pharynx or lower respiratory tract.Incubation: short: 1-3 days. Rapid spread leads to epidemics.M. A. El-Farrash
30 Laboratory Diagnosis A. Viral Isolation : B. Serology : Samples: Respiratory secretions: obtained by direct aspirate, gargle or nasal washings.Rapid examination of cells by IF then inoculation on cell cultures (or egg embryo).PCR and genotyping or serotyping.B. Serology :Detection of antibodies in the serum by HAI.M. A. El-Farrash
31 Treatment of Influenza Amantadine and Rimantadine are active against influenza A viruses (but not B).Recently, they became not effective against seasonal strains.Tamiflu: is an inhibitor of neuraminidase taken in pill form which causes decreased severity and duration of symptoms.M. A. El-Farrash
32 Influenza vaccinesVaccines are produced by re-assortment of egg-adapted strains with strains having the season HA type.Large amounts of virus are then grown in embryonated eggs (cheap and efficient), purified and formalin inactivated.The vaccine is given sub-cutaneously.For new antigenic type, 2 doses are necessary for adequate protection (which depends on age of patient).M. A. El-Farrash
35 Diarrhea Viruses Diarrhoa is not as dramatic illness as AIDS. However, the virusescausing diarrhea are ofgreat economic importance.Diarrhea viruses include : Astroviruses, Adenoviruses, Reoviruses and Caliciviruses.
36 ReovirusesRespiratory Enteric Orphan viruses, i.e. viruses that infect the human respiratory and intestinal tracts, without causing a known disease.There are more than 150 species in the family Reoviridae. The most important one is Rotavirus.They are unified by their most unique feature; the composition of their genome d/s RNA.M. A. El-Farrash
37 RotavirusesRotaviruses have three shells: an outer capsid, inner capsid and core which surrounds the 11 segments of double-stranded RNA.M. A. El-Farrash
38 RotavirusesInfections cause endemic/epidemic gastroenteritis and infantile diarrhea (a major cause of death in the developing world).Rotaviruses cause generally self-limited infections rare in adults and trivial in consequence, but may kill infants unless properly treated (oral rehydration keeps children alive).
39 RotavirusesRotaviruses are the most common cause of severe diarrhea worldwide.In developing countries, rotavirus infection may cause up to one million deaths each year, accounting for an estimated 20-25% of all deaths due to diarrhea and 6% of all deaths among children less than five years old.M. A. El-Farrash
40 Diagnosis and Management Infection occurs by feco-oral route.Diagnosis is confirmed by virus detection in stool by E/M or isolation by culture.Treatment : oral rehydration therapy with isotonic glucose/mineral salt solution.M. A. El-Farrash
42 Astroviruses are 28–35 nm, icosahedral viruses that have a characteristic five- or six pointed star-like surface structure when viewed by electron microscopy. Astrovirus has a non-segmented, single stranded, positive sense RNA genome within a non-enveloped icosahedral capsid. They have been shown to be an important cause of gastroenteritis in young children worldwide.
44 Norwalk “Norovirus”Norovirus is a genus of single-stranded RNA, non-enveloped viruses in the Caliciviridae family.The known viruses in the genus are all considered a single species called Norwalk virus.Noroviruses are the most common cause of viral gastroenteritis in humans, and affect people of all ages.
45 Norwalk “Norovirus”The viruses are transmitted by contaminated food or water; by person-to-person contact; and via aerosolization of the virus and subsequent contamination of surfaces.The virus causes over 200,000 deaths each year; these deaths are usually in less developed countries and in the very young, elderly and immunosuppressed.
46 Norwalk “Norovirus”Norovirus infection is characterized by nausea, forceful vomiting, watery diarrhea, and abdominal pain, and in some cases, loss of taste.General lethargy, weakness, muscle aches, headache, coughs, and low-grade fever may occur.The disease is usually self-limiting, and severe illness is rare.
48 Viral MeningitisViral meningitis is sometimes referred to as "aseptic meningitis" in contrast to meningitis caused by bacteria.Viral meningitis is most commonly caused by enteroviruses, however, only a small number of people with enterovirus infections actually develop meningitis.
49 Viral Meningitis Causative organisms include: Enteroviruses Echovirus Poliovirus (PV1, PV2, PV3)Coxsackie A virus .Other viral infections that can lead to meningitis includeHerpesviruses,Arboviruses
50 Viral MeningitisLCMV (lymphocytic choriomeningitis virus), which is spread by rodents,Human Immunodeficiency Virus (HIV)MeaslesMumpsSt. Louis Encephalitis virusWest Nile virus