Viral Disease Course Materials

Rabies The word rabies comes from the Sanskrit word rabhas which means "to rage" while in Latin rabere (angry) (Leung et al., 2007) or in Indonesia it is known as a mad dog. The cause of rabies is an RNA virus which is a member of the genus Lyssavirus, family Rhabdoviridae, order Mononegaviral. The rabies virus genome is:Ribonucleic acid(RNA) singlestranded, antisense, unsegmented, with a molecular weight of 12 kb consisting of 50 nucleotides along with the genes nucleoprotein (N), phosphoprotein (P), matrix protein (M), glycoprotein (G), and the large protein (L). Rabies virus (RABV) is the species responsible for the majority of cases in humans and animals. Previously, one type of virus was believed to be responsible for all rabies. Modern techniques with antigen detection have shown that several viruses and at least 6 serotypes in the Lyssavirus genus cause diseases clinically related to rabies. The rabies virus is most often transmitted through the bite of a rabid animal (appendix). This mechanism allows the virus to cross the dermal barrier and deposit the virus into the tissue where it can initiate infection. The pathogenesis of rabies is as follows: the virus enters the host's muscle tissue through a bite wound, then enters the peripheral nervous system (CNS) through the neuromuscular junction, and then travels from the CNS to the spinal cord and brain. The virus enters the brain and undergoes extensive replication causing neural dysfunction (virus in cerebellar Purkinje cells 40x magnification). The virus replicates in the salivary glands and is excreted in saliva, enters the peripheral nerves of the skin and Purkinje cells, and spreads from the brain to infect many tissues and organs in the host. Rabies progresses through 5 clinical stages with much variability, depending on the extent of the bite, the amount of secretions encountered, and proximity to the CNS, i.e. disease transmitted through bites close to the brain will progress more rapidly than disease transmitted through bites in the lower extremities. Incubation-ranges from 10 days to 1 year (average, 20-60 days). The incidence of rabies in animals and humans almost always ends in death so that as a result this disease causes fear, worry and unrest in the community. Infection in dogs and cats is characterized by looking for cold places, hydrophobia followed by suspicious behavior and attacking everything around them, paralysis and death. Avian Influenza Avian Influenza(AI) or bird flu is an infectious disease caused by the H5N1 type AI virus. The bird flu virus genome is a single-stranded RNA virus that has an envelope with eight segments, negative polarity and a round or filament shape. This virus belongs to the Orthomyxoviridae family. Based on differences in nucleoprotein antigens and the matrix that makes them up, this virus is classified into three types, namely influenza virus types A, B and C. Influenza A viruses are found in birds, humans, pigs, horses and sometimes in other mammals, for example minks, seals. and whales. Meanwhile, Influenza B and C viruses are only found in humans. Each segment of the type A influenza virus consists of proteinsPolymerase component 2(PB2),Polymerase component 1(PB1) andPolymerase component(PA) which encodes Polymerase, Haemagglutinin (HA),Nucleocapsid(NP),Neuraminidase(NA),Matrix Proteins 1(M1), Matrix Protein 2 (M2),Non Structural Protein 1(NS1) and Non Structural Protein 2 (N2). These proteins have their respective roles in the life of the type A influenza virus. Avian Influenza virus remains infective in feces for 30 ‒ 35 days at 4°C and for 7 days at 20°C. This shows that the Avian Influenza virus can survive in the environment for a period of timeand a certain temperature. This characteristic allows the spread of the Avian Influenza virus in nature. Avian influenza infects various species of birds and mammals. It is a major cause of morbidity and mortality in humans during annual epidemics. Bird flu primarily infects the epithelium of the upper and lower respiratory tract, usually resulting in respiratory system fluctuations characterized by fever, myalgia, upper respiratory tract congestion and pharyngitis. The source of the virus is thought to come from bird migration and transportation of infected birds. The virus is transmitted through fluid/mucus originating from the nose, mouth, eyes (conjunctiva), and feces (feces) from sick birds into the environment. Direct contact with sick livestock, via aerosol (air) in the form of splashes of liquid/mucus, water, and equipment contaminated with the AI virus. This virus is a type of virus that is unstable and has many variations and mutates easily. Clinical symptoms in adult chickens usually include rotating wattles and edema around the eyes. The wattles are often cyanotic and contain fluid or blood vesicles on the surface with dark areas of eccymatous hemorrhage and necrosis. The last eggs after the onset of the disease usually have no shell. Diarrhea begins as a bright green liquid and progresses to almost all white. Edema of the head, if present, is often accompanied by edema of the neck. The conjunctiva and feet are affecteddiffuse hemorrhage. Respiratory symptoms may be significant in this disease, depending on the severity of the trachea. The accumulation of mucus fluid may varyThe high death rate due to bird flu usually occurs at the same time as a potential epidemic in humans, so greater attention is focused on humans because the bird flu virus is highly pathogenic in humans. The natural reservoir of the bird flu virus is waterfowl. Waterfowl can be infected by avirulent or low pathogenic strains of avian influenza virus by showing mild clinical symptoms or without showing any clinical symptoms at all. Influenza viruses are secreted in the feces of birds infected with bird flu and transmission occurs directly or indirectly. Bluetongue (BT) Bluetongue (BT) disease was first discovered as early as 1876 in South Africa in sheepImported Merino.Bluetongueis a disease of the arbovirus genus, arbovirus of the Reoviridae family, which is infectious, non-contagious, and transmitted through the insect Culicoides spp. This disease can attack ruminant livestock such as cows, buffalo, sheep and goats, as well as wild livestock such as deer, causing significant economic losses. BT virus is a virusRibonucleic Acid(RNA) which has 10 double stranded RNA segments with a virus diameter ranging from 40-80 nm Unlike other Arbo viruses, BT disease is not transmitted to humans. This virus is pathogenic for domestic and wild ruminants. This virus mostly attacks sheep from Europe which is developed commercially and is widely distributed to Africa, Asia and Australia. In cattle and goats it rarely causes clinical disease and the symptoms are much milder than in sheep. Currently, there are at least 24 serotypes of BT virus known in the world. The spread of the BT virus disease in Europe is closely related to the expansion of its vector, the mosquitoCulicoides imicola, where at that time there had been quite hot climate changes with increased humidity. In sheep, sensitivity is very dependent on the type (breed) and type of BT virus infecting. South African breeds of sheep such as the Afrikander, Persian and Awassi breeds are more sensitive than local African sheep in general,but South African breed sheep are less sensitive than Merino sheep, while Merino sheep are less sensitive than Dorset- Horn breed sheep. Local Indonesian sheep are also less sensitive to BT infection Clinical symptoms due to BT infection include fever, hyperemia of the mucous membranes of the mouth, eyes and nose, ulcers in the oral cavity, edema on the lips, face and eyes so that the animal is reluctant to eat, which causes the animal to become weak. In pregnant sheep, BT infection can cause miscarriage and temporary infertility. Apart from miscarriage, abnormalities such as stillbirth and deformities in lambs that are born often occur.