Lecture 2 Diseases from Viruses PDF

SSCY2633 VIROLOGY Diseases from Viruses DR. NURZILA AB LATIF 24/25-2  What Are Infectious Diseases? Infectious diseases are caused by viruses that can make us sick. Introduction to Viral Hepatitis Viral Hepatitis is a significant global health con...

SSCY2633 VIROLOGY Diseases from Viruses DR. NURZILA AB LATIF 24/25-2  What Are Infectious Diseases? Infectious diseases are caused by viruses that can make us sick. Introduction to Viral Hepatitis Viral Hepatitis is a significant global health concern affecting millions. It encompasses several types, including Hepatitis A, B, C, D, and E. Understanding its epidemiology, prevention, and treatment strategies is crucial for effective public health interventions. Epidemiology of Viral Hepatitis The epidemiology of viral hepatitis varies by type and region. Hepatitis B and C are often chronic and lead to serious health complications like cirrhosis and liver cancer. Hepatitis A and E are typically acute and linked to contaminated food and water. Transmission Routes Understanding the transmission routes is key to prevention. Hepatitis A and E are primarily transmitted through fecal-oral routes, while Hepatitis B and C spread through blood and bodily fluids. Vaccination and safe practices are essential for control. Influenza Orthomyxoviridae (a group of RNA viruses). Categorized as types A, B, C, and D. These major types generally produce similar symptoms but are completely unrelated antigenically, so that infection with one type confers no immunity against the others. The A viruses cause the great influenza epidemics, and the B viruses cause smaller localized outbreaks. The C viruses cause only mild respiratory illness in humans. Influenza D viruses are not known to infect humans and have been observed only in pigs and cattle. Influenza A viruses are classified into subtypes, and both influenza B and subtypes of influenza A are further divided into strains. Subtypes of influenza A are differentiated mainly on the basis of two surface antigens (foreign proteins)—hemagglutinin (H) and neuraminidase (N). Examples of influenza A subtypes include H1N1, H5N1, and H3N2. Influenza B viruses are subdivided into two major lineages, B/Yamagata and B/Victoria. Strains of influenza B and strains of influenza A subtypes are further distinguished by variations in genetic sequence. Between worldwide outbreaks, known as pandemics, influenza viruses undergo constant, rapid evolution (a process called antigenic drift), which is driven by mutations in the genes encoding antigen proteins. Periodically, the viruses undergo major evolutionary change by acquiring a new genome segment from another influenza virus (antigenic shift), effectively becoming a new subtype. Viral evolution is facilitated by animals such as pigs and birds, which serve as reservoirs of influenza viruses. When a pig is simultaneously infected with different influenza A viruses, such as human, swine, and avian strains, genetic reassortment can occur. This process gives rise to new strains of influenza A. Mumps By PARAMYXOVIRUS Characterized by painful swelling of the salivary glands (particularly the parotid gland) accompanied with high fever and the movement of the jaws becomes very difficult. In adults, the reproductive glands (both testes and ovaries) may also become inflamed  Chicken pox By Vericella zoster virus highly contagious, generally in children less than 10 years old. Poliomyelitis Caused by the smallest known virus, ENTEROVIRUS. It multiplies in the cells of intestinal wall and then the infection spreads through the blood stream and lymphatic system. The virus mainly attacks the central nervous system and results in weaken of the muscles of arms and legs as these muscles do not get the nerve impulses. It usually leads to PARALYSIS.  Common cold Caused by RHINOVIRUS (‘rhino’ in Latin means nose) The viruses are transmitted through droplet nuclei, pharyngeal and nasal secretions. Symptoms include headache, watery eyes, sneezing, excessive nasal secretions and cough.  Dengue fever by RNA CONTAINING DENGUE VIRUS (DENV). It is transmitted by the bite of female tiger mosquito AEDES AEGYPTI during day time. Two types of dengue fever are : Classical dengue fever : More severe in adults and characterized by mild conjunctivitis, high fever, backache, retro-orbital pain (pain behind the eye ball). Dengue HAEMORRHAGIC fever: Fatal, form with nausea, headache, vomiting abdominal pain.  Yellow fever Caused by ARBOVIRUS. It is transmitted by the infected AEDES AEGYPTI. The "yellow" in the name refers to the jaundice that affects some patients. Symptoms are headache, fever, vomiting, rupture of veins in kidneys, spleen, liver.  Foot-and-Mouth Disease (FMDV) ANIMAL DISEASES Monkeypox by Orthopoxvirus African Swine Fever (ASF) Bluetongue by Orbivirus Sheep pox and goat pox by Capripox virus  Foot-and-mouth disease FOOT-AND-MOUTH DISEASE VIRUS (FMDV) causes this disease in ruminants like cattle, sheep and pigs worldwide. Not fatal to adult animals normally but causes significant loss of productivity; for example milk yields may drop. The disease is characterised by high fever that declines rapidly after two or three days and the development of vesicles and erosions inside the mouth and on the feet. Monkeypox Caused by ORTHOPOXVIRUS It causes disease in monkeys, but its reservoir hosts probably are squirrels and other rodents. Monkeypox is a zoonosis (disease or infection that is naturally transmissible from vertebrate animals to humans), it can be transmitted to humans. Disease in humans is similar to smallpox, but usually milder. African swine fever (ASF) It is caused by a large DNA virus belonging to the FAMILY ASFARVIRIDAE, GENUS ASFIVIRUS in pigs. ASF is mainly found in sub-Saharan Africa, but recently, ASF outbreaks occurred also in e.g. Georgia, Armenia, and Russia. Bluetongue by an ORBIVIRUS (family Reoviridae) in sheep and cattle. Bluetongue virus (BTV) does not infect humans. Meat and other products of infected animals can be consumed without risk. Symptoms of BT include lesion of the nasal and oral mucosal surfaces, fever, laziness, nasal discharge, tissue infarctions. Vaccination of ruminants against BTV-8 is currently the only effective means of protection against clinical disease and animal losses.  Sheep pox and goat pox by CAPRIPOX VIRUSES in sheep and goat. highly contagious diseases of small ruminants. Initial clinical symptoms are fever, increased salivation and nasal and ocular discharge. Within a few days, papules, nodules and vesicles appear on the head, in the genital area and on the udder. The lesions can take up to six weeks to heal. High mortality can occur in lambs, when mucosal surfaces of the alimentary and respiratory tracts are severely affected. Massive lesions in these areas can give rise to secondary bacterial infections.  Questions Remember, preventing infections helps us all stay healthy and happy. Any questions?