DR. MOHAMMED ARIF ASSOCIATE PROFESSOR CONSULTANT VIROLOGIST HEAD OF THE VIROLOGY UNIT Viral infection of the respiratory tract --- 1

Respiratory tract infection Respiratory tract infections are common in both children and adults. Mostly caused by viruses. مهمه Mostly are mild and confined to the upper respiratory tract(URT). Mostly are self limiting. لا تحتاج علاج URT-infection may spread down ward and causes more severe infection and even death.

Clinical manifestations المظاهر الاكلينيكيه Common cold (coryza زكام, rhinitis). Pharyngitis. التهاب البلعوم Tonsilitis. Sinusitis التهاب الجيوب & otitis media التهاب الاذن الوسطى. Croup مرض الخانوق ( acute laryngotracheobronchitis). Acute bronchitis. Acute bronchiolitis. Viral pneumonia. Influenza ( Flu ). لها شرائح منفصله

Respiratory tract.

1- Rhinoviruses. Family: Picornaviridae. Genus : Rhinovirus. لا تحفظه Unenveloped. Small icosahedral له عشرين وجه particle, nm in diameter. The viral genome is ss-RNA, with positive polarity. More than 100 types. لكل انواع الفيروسات : اعرف العائله فقط ونوع الحمض النووي واعرف هل الفيروس Enveloped or unenveloped الاشياء الاضافيه سيتم الاشاره لها الدكتور يقول : اي خط عريض معناه مهم

EM of rhinoviruses.

Corona التاجيه viruses. Family: Coronaviridae. Irregular in shape. Enveloped with club shaped glycoprotein spikes سبب تسميتها بالتاجيه وجود. Helical nucleocapsid. The viral genome is ss-RNA, with positive polarity.

EM of corona viruses.

Rhino and corona viruses are the major cause of common cold. معلومه مهمه جدا ( سؤال )  Common cold :  inflammation of the nose and throat (nasopharynx), characterized by watery nasal discharge and sneezing.  It is a highly contagious معدي disease.

General characteristics of rhinoviruses. They replicate in the nasopharynx. They are sensitive to acids. معلومه مهمه ركز عليها الدكتور - لذلك تموت هذه الفيروسات مباشره عند دخولها المعده - Shed سيلان in large amounts in nasal secretion. Transmitted by inhalation of respiratory droplets during sneezing and coughing The optimal temperature for their replication is c. Do not efficiently بشكل فعال replicate at body temperature.

Common cold

Transmission  By inhalation of respiratory droplets, during sneezing and coughing.  Through contaminated hands. Target group:  both children and adults.

Clinical features  IP: 1-3 days. لا تحفظها ( الكلام عام لكل الفيروسات ) Symptoms:  Watery nasal discharge.  Sneezing.  Mild sore throat.  Fever is not common. معلومه مهمه جدا

Prognosis and lab. diagnosis Prognosis:  Self-limiting disease.  Recovery is complete. Lab. Diagnosis:  Not needed, diagnosis is made on the basis of clinical symptoms.

Treatment  There is no specific anti-viral drug therapy.  Treatment is supportive.

2- Parainfluenza viruses. Family : Paramyxoviridae. Genus :Respirovirus. غير مهمه Large, nm in diameter. Pleomorphic متعدد الاشكال, helical nucleocapsid. Enveloped with two glycoprotein spikes, HN and F الاحمر قراءه فقط. The viral genome is ss-RNA with negative polarity.

Parainfluenza viruses. قراءه بتركيز The HN has both hemagglutinine and neuraminidase activities. Attachment proteins. They bind to specific receptors on the cell membrane. The F ( fusion ), mediates cell entry by the fusion process The viral genome is ss-RNA, with negative polarity.

Respiratory syncytial virus ( RSV ). Family : Paramyxoviridae. Genus : Pneumovirus. الغير مهمه Large, nm. Pleomorphic, helical nucleocapsid. Enveloped with two glycoprotein spikes, G and F. The viral genome is ss-RNA with negative polarity.

RSV. قراءه بتركيز The G protein, lack hemagglutinine and neuraminidase activities. Attachment protein. The F, Mediates cell entry, by fusion process.

Diseases مهمه جدا جدا 1- Croup ( acute laryngotracheobronchitis ). Caused mainly by parainfluinza type I, II مهمه جدا Parainfluenza types 1 and 2 are the major cause of croup in infants and young children. RSV. Influenza A.

Croup  Acute inflammation of the larynx and trachea in infants and young children.  Usually caused by viruses.  Characterized by swelling of the epithelial cells lining the air way, so that the air way narrows and breathing becomes difficult.

Transmission  By inhalation of respiratory droplets. Target groups:  Children between six months to three years.

Symptoms  Usually preceded تسبق بـ by a cold symptoms.  Fever.  Respiratory distress ( difficult and labored breathing ).  Barking spasmodic cough.  Inspiratoty stridor.  Hypoxia and cyanosis

Prognosis  In mild cases, recovery is usual in 3-5 days.  Small proportion of cases proceed تتطور to bronchiolitis and pneumonia.

Lab. diagnosis  Specimen, is nasopharyngeal aspirate (NPA).  By direct demonstration ايضاح of the virus in the infected cells, inside the NPA.

Nasopharyngeal aspirate

2 -Bronchiolitis  Inflammation of the bronchioles in infants and young children. Bronchioles become inflamed, edematous and obstructed by mucous. Viral etiology :  Mostly caused by viruses.  Respiratory syncytial virus ( RSV ) and parainfluenza virus type 3 are the major cause of bronchiolitis in infants. المعلومه مهمه جدا وسؤااال

Bronchiolitis  Influenza A viruses.  Adenoviruses. Transmission : By inhalation of respiratory droplets. Target group : Infants less than 18-months.

Bronchiolitis Symptoms :  Usually preceded by URT symptoms.  Expiratory obstruction.  Expiratory wheezing.  Respiratory distress ( difficult & labored breathing ).  Hypoxia and cyanosis.

Bronchiolitis Prognosis and treatment.  Most cases are mild,recover completely & do not require hospitalization.Increasing respiratory distress, cyanosis, fatigue or dehydration are indication for hospitalization. Lab diagnosis. By direct demonstration of the viral antigens in the nasopharyngeal aspirate, using immuno flourescent technique.

Viral pneumonia  Inflammation of the lung and alveoli.  The most commonly caused viruses are:  RSV and parainfluenza virus type-3 are the major cause of infantile الاطفال pneumonia.  Influenza A viruses.  Adenoviruses.

5-Viral pneumonia  Human metapneumovirus.  CMV in the immunocompromised.  Varicella-zoster virus in adults. Transmission : by inhalation of respiratory droplets during sneezing and coughing. Target groups: young children and the immunocompromised.

Viral pneumonia

Symptoms: usually preceded by the URT symptoms.  Fever.  Chills.  Pharyngitis.  Cough.  Shortness of breath.  Muscle aches.  Fatigue.  Chest pain.

Viral pneumonia Prognosis: Most cases are mild and get better without treatment.  Some cases are more serious and require hospitalization.  Complications: Respiratory failure, heart failure and liver failure.

Viral pneumonia Treatment : Specific anti-viral drugs are available for:  CMV, ganciclovir.  VZV, ganciclovir.  Influenza A, amantadine and remantadine

Lab. diagnosis  For RSV, influenza & parainfluenza viruses : Detection of the viral antigen in the nasopharyngeal aspirate (NPA), using direct immuno fluorescence.  For adenoviruses : Isolation of these viruses in tissue culture, followed by identification of the isolated virus. Specimens: NPA, throat swab, bronchial wash.

Adenoviruses. Family : Adenoviridae.  Icosahedral, nm in diameter.  Unenveloped ( naked ).  One spike ( fiber ) at each vertex.  The viral genome is linear ds-DNA.  51- human adenoviruses, grouped in 6-species A-F.

EM of adenoviruses,

Adenoviruses Transmission:  Respiratory infection,by inhalation of respiratory droplets. -- Through contaminated hands. -- Direct contact with contaminated surfaces.  Intestinal tract infection: -- By the fecal oral route.

Adenoviruses.  Eye infection: -- Through contaminated hands. -- Using contaminated towels. -- Using contaminated eye-drops, ophthalmic instruments. Target groups : Children and adults.

Adenoviruses. Diseases associated with adenoviruses: مهمه جدا جدا  Keratoconjunctivitis. الالتهاب الجاف للقرنيه والملتحمه بالعين  Pharyngo -conjunctival fever.  Acute respiratory diseases.  Gastroenteritis.  Urinary tract infection.  Meningitis.

Adenoviruses. Prognosis:  Self- limiting disease.  Recovery is usual.

Adenoviruses. Treatment:  There is no anti-viral drug therapy.  Treatment is supportive. Lab diagnosis:  By isolation of the virus in tissue culture, followed by identification of the isolated virus.

Adenoviruses. Prevention:  There is no vaccine available yet. تابع المحاضره في السلايدات في الملف الاخر : تتحدث عن الانفلونزا