Mumps & Herpes Simplex Virus PDF

# Infectious Diseases ## Mumps **Is a viral disease caused by the mumps virus. Initial symptoms are non-specific and include fever, headache, malaise, muscle pain, and loss of appetite. These symptoms are usually followed by painful swelling of the parotid glands, called parotitis, which is the mo...

# Infectious Diseases ## Mumps **Is a viral disease caused by the mumps virus. Initial symptoms are non-specific and include fever, headache, malaise, muscle pain, and loss of appetite. These symptoms are usually followed by painful swelling of the parotid glands, called parotitis, which is the most common symptom of infection. Symptoms typically occur 16 to 18 days after exposure to the virus and resolve within two weeks. Complications include deafness and a wide range of inflammatory conditions, of which inflammation of the pancreas, meninges, and brain are the most common. Testicular inflammation may result in reduced fertility and, rarely, sterility.** - **Causes:** - Mumps is caused by the mumps virus (MuV), scientific name Mumps orthorubulavirus, which belongs to the Orthorubulavirus genus in the Paramyxoviridae family of viruses. Humans are the only natural host of the mumps virus. - MuV's genome is made of RNA and contains seven genes that encode nine proteins. - In MuV particles, the genome is encased by a helical capsid. The capsid is surrounded by a viral envelope that has spikes protruding from its surface. - **Pathogenesis:** - After initial infection, the virus spreads to the parotid glands, causing the signature parotitis. - It is thought that shortly after infection the virus spreads to lymph nodes, in particular T-cells, which results in the presence of viruses in the blood, called viremia. - Viremia lasts for 7–10 days, during which MuV spreads throughout the body. - **In mumps orchitis, infection leads to:** - parenchymal edema - congestion, or separation, of the seminiferous tubules - perivascular infiltration by lymphocytes. - The tunica albuginea forms a barrier against edema, causing an increase in intratesticular pressure that causes necrosis of the seminiferous tubules. - The seminiferous tubules also experience hyalinization, i.e., degeneration into a translucent glass-like substance, which can cause fibrosis and atrophy of the testes. - **The replication of the virus:** - The replication cycle of MuV begins when the spikes on its surface bond to a cell, which then causes the envelope to fuse with the host cell's cell membrane, releasing the capsid into the host cell's cytoplasm. - Upon entry, the viral RNA-dependent RNA polymerase (RdRp) transcribes messenger RNA (mRNA) from the genome, which is then translated by the host cell's ribosomes to synthesize viral proteins. - RdRp then begins replicating the viral genome to produce progeny. - Viral spike proteins fuse into the host cell's membrane, and new virions are formed at the sites beneath the spikes. - MuV then utilizes host cell proteins to leave the host cell by budding from its surface, using the host cell's membrane as the viral envelope. - **Transmission:** - The mumps virus is mainly transmitted by inhalation or oral contact with respiratory droplets or secretions. - In experiments, mumps could develop after inoculation either via the mouth or the nose. - Respiratory transmission is also supported by the presence of MuV in cases of respiratory illness without parotitis, detection in nasal samples, and transmission between people in close contact. - MuV is excreted in saliva from approximately one week before to eight days after the onset of symptoms, peaking at the onset of parotitis, though it has also been identified in the saliva of asymptomatic individuals. - Mother-to-child transmission has been observed in various forms. - In non-human primates, placental transmission has been observed, which is supported by isolation of MuV from spontaneous and planned aborted fetuses during maternal mumps. - MuV has also been isolated from newborns whose mother was infected. - While MuV has been detected in breast milk, it is unclear if the virus can be transmitted through it. - Other manners of transmission include direct contact with infected droplets of salivaand possibly urine. - Most transmissions likely occur before the development of symptoms and up to five days after such time. - **Prevention:** - Infection can be prevented with vaccination, either via an individual mumps vaccine or through combination vaccines such as the MMR vaccine, which also protects against measles and rubella. - The spread of the disease can also be prevented by isolating infected individuals. - **Diagnosis:** - In places where mumps is widespread, diagnosis can be made based on development of parotitis and history of exposure to someone with mumps. - In places where mumps is less common, because parotitis has other causes, laboratory diagnosis may be needed to verify mumps infection. - A differential diagnosis may be used to compare symptoms to other diseases, including allergic reaction measles, and rubella. - MuV can be isolated from saliva, blood, the nasopharynx, salivary ducts, and seminal fluid within one week of the onset of symptoms, as well as from cell cultures. - Mumps-specific IgM antibodies in serum or oral fluid specimens can be used to identify mumps. - IgM quantities peak up to eight days after the onset of symptoms, and IgM can be measured by enzyme-linked immunosorbent assays (ELISA) 7–10 days after the onset of symptoms. - Real-time reverse transcription polymerase chain reaction (rRT-PCR) can be used to detect MuV RNA from the first day symptoms appear, declining over the next 8–10 days. - rRT-PCR of saliva is typically positive from 2–3 days before parotitis develops to 4-5 days after. - **Treatment:** - There is no specific treatment for mumps, so treatment is supportive in nature and includes bed rest and pain relief. - Prognosis is usually excellent with a full recovery as death and long-term complications are rare. - Mumps is usually self-limiting, and no specific antiviral treatments exist for it, so treatment is aimed at alleviating symptoms and preventing complications. - Nonmedicinal ways to manage the disease include bed rest, using ice or heat packs on the neck and scrotum, consuming more fluids, eating soft food, and gargling with warm salt water. - Anti-fever medications may be used during the febrile period, excluding aspirin when given to children. - Analgesics may also be provided to control pain from mumps inflammatory conditions. ## Herpes Simplex Virus **Herpes simplex virus 1 and 2 (HSV-1 and HSV-2), also known by their taxonomical names Human alphaherpesvirus 1 and Human alphaherpesvirus 2, are two members of the human Herpesviridae family.** - **Herpes can appear in various parts of the body, most commonly on the genitals or mouth. There are two types of the herpes simplex virus:** - HSV-1: primarily causes oral herpes, and is generally responsible for cold sores and fever blisters around the mouth and on the face. - HSV-2: primarily causes genital herpes, and is generally responsible for genital herpes outbreaks. - **Viral structure:** - Herpesviruses have a unique four-layered structure: a core containing the large, double-stranded DNA genome is enclosed by an icosahedral capsid which is composed of capsomers. - The capsid is surrounded by an amorphous protein coat called the tegument. - It is encased in a glycoprotein-bearing lipid bilayer envelope. - **Symptoms:** - Many of those who are infected never develop symptoms. - Symptoms, when they occur, may include watery blisters in the skin or mucous membranes of the mouth, lips, nose, or genitals. - Lesions heal with a scab characteristic of herpetic disease. - **Transmission:** - There are two types of herpes simplex virus, type 1 (HSV-1) and type 2 (HSV2). - HSV-1 More commonly causes infections around the mouth while HSV-2 more commonly causes genital infections. - They are transmitted by direct contact with body fluids or lesions of an infected individual. - Most sexual transmissions (HSV-2 ) occur during periods of asymptomatic shedding. - Both viruses may also be transmitted vertically during childbirth. - However, the risk of infection transmission is minimal if the mother has no symptoms or exposed blisters during delivery. - The risk is considerable when the mother is infected with the virus for the first time during late pregnancy. - Herpes cannot be transmitted from surfaces such as toilet seats because the herpes virus begins to die immediately after leaving the body. - **Lab. Diagnosis:** - Laboratory tests include culture of the virus, direct fluorescent antibody (DFA) studies to detect virus, skin biopsy, and polymerase chain reaction to test for presence of viral DNA. - Serological tests for antibodies to HSV were rarely useful to diagnosis and not routinely used in clinical practice. - **Treatment:** - To treat early-onset oral herpes, oral antiviral medications can help relieve pain and reduce healing time. - For the treatment of recurrent herpes, the mainstay of treatment is to reduce the severity and duration of the outbreak, with the following medications: - Topical ointments or creams (available with or without prescription): Effective in reducing pain, itching, and shortening healing time. - Oral antiviral drugs (available by prescription only): Use at the first sign of illness (such as heat, itching). This medicine has little effect when the blisters are already swollen.