Microbiology topic 14
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Created by:
sesherwood on November 28, 2010
Subjects:
viral infections of the blood, lymphatic, gastrointestinal, and nervous systems
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42 terms
Terms | Definitions |
|---|---|
 HIV | Human Immunodeficiency Virus (HIV) is responsible for HIV disease and AIDS. Acquired immunodeficiency syndrome (AIDS) first appeared in the U.S. in 1981. Luc Montagnier and Robert Gallo first isolated and cultured the human immunodeficiency virus type 1 and linked it to AIDS. HIV is a member of the Retroviridae family, contains 2 copies of single-stranded RNA. HIV-2 is a second type of HIV, which develops more slowly than HIV-1. |
| HIV infection | Its genome is packaged with reverse transcriptase. Once the RNA is transcribed into double-stranded DNA, the DNA integrates into the host DNA as a provirus. HIV normally infects the immune system cells, including T lymphocytes (CD4+T cells). 2-3 weeks after infection, 50% of T cells are destroyed. B lymphocytes are also paralyzed. Incapacitation of T lymphocytes allows opportunistic pathogens to infect the body. HIV also infects and paralyzes B lymphocytes. |
| HIV Stages | Stage 1- can include a flu-like illness within a month or two of exposure; Seroconversion means the immune system is activated against the virus, and antibodies can be detected in the blood. Stage 2- the individual usually remains free of major disease, even without treatment; it can last 6-8 years, during which HIV levels in the blood slowly rise. Stage 3- occurs when the immune system loses the fight against HIV. Symptoms worsen and opportunistic infections develop. T cell count below 200/mm(cubed) of blood, person has AIDS. |
| HIV transmission | HIV is transmitted through blood and sexual contact. Health care workers can be at risk through events such as needle sticks. Infected mothers can transmit the virus to their fetus or to the baby during birth or breastfeeding. Blood tests using ELISA are used to detect antibodies in the blood. A test done during the first 3 moths of infection may not be accurate (later test recommended). Prevention requires avoiding risky behaviors like sharing needles or unprotected sex. |
| HIV treatment | Azidothymidine (AZT) was the first drug used for treatment. It interferes with reverse transcriptase activity. HIV can become resistant to some antivirals. This requires a cocktail of drugs called highly active antiretroviral therapy (HAART). HAART reduces the risk of HIV transmission and can extend life of patients by about 8 years. A vaccine has not yet been developed. HIV continually mutates and recombines, making vaccine development difficult. A vaccine needs to activate T lymphocytes, which are the cells infected by the virus. |
| Infectious monoculeosis | a blood disease, it particularly affects B lymphocytes in the lymph nodes and spleen. Spread by contact with saliva. it is caused by the Epstein-Barr virus (EBV). Many children are infected and show no symptoms. Symptoms include sore throat, swollen glands, fever; duration about 3-4 weeks. Adolescents or young adults who are infected may develop EBV disease (a precursor of mononucleosis). |
| Infectious mononucleosis complications | Include: Heart defects, facial paralysis, rupture of the spleen, jaundice (hepatitis). After recovery, the individual remains a carrier for several months, can shed the virus in their saliva. Diagnosis involves observation of: elevated lymphocyte levels, presence of Downey cells (damaged B cells). Antibodies can be detected by the monospot test. No vaccine or drugs for treatment are available. |
| EBV can also cause... | EBV is associated with Burkitt lymphoma, a tumor of the jaw prevalent in Africa. The malaria parasite might help stimulate tumor development. EBV is also associated with: 1) T cell malignancies, including nasopharyngeal carcinoma. 2) B cell lymphoma. 3) Hodgkin disease. 4) Multiple sclerosis. |
| CMV | Cytomegalovirus disease can produce serious birth defects. CMV disease is common, producing infectious mononucleosis-like symptoms. The virus may pass into the fetus of a pregnant woman, causing mental impairment. In immunocompromised people, it can reactivate: this can accelerate the progression of HIV to AIDS and infecting many bodily tissues. |
| Hepatitis B Virus | (HBV) is a global health problem, member of the family Hepadnaviridae. Virions consists of: a nucleocapsid surrounded by a core antigen (HBcAg); an envelope containing a surface antigen (HBsAg). Transmission usually involves direct or indirect contact with a bodily fluid. |
| HBV symptoms | during the 1-6 month incubation period, the virus infects the liver. Primary symptoms include fatigue, loss of apetite, nausea, vomiting. Jaudice occurs after primary symptoms; abdominal pain. Recovery occurs 3-4 months after the onset of jaundice, after which an immunity is developed. Persistent infections, cirrhosis, or liver cancer occur rarely. Several vaccines and drugs for treatment are available. |
| Hepatitis C Virus | belongs to the Flaviviridae family. It is transmitted by blood. Few symptoms are associated with primary infection. Most cases develop a symptomless chronic infection, involving cirrhosis and other complications. HCV damage is the primary reason for liver transplants in the U.S. Damage is accelerated by alcoholism and drug use. |
| Hepatitis D and G | Hepatitis D is caused by HBV and Hepatitis D virus (HDV). HDV can only damage the liver when HBV is present. Hepatitis G is another chronic liver disease transmitted by blood or sexual contact. |
| Viral Diseases causing Hemorrhagic fevers | 1) Yellow fever 2) Dengue fever. 3) HPS. 4) Sandfly fever. 5) Rift vally fever. 6) EHF. 7) MHF. 8) Lassa fever. 9) several others that are not explained. |
| Yellow fever | Flaviviruses can cause a terrifying and severe illness. They are also called arboviruses because they are arthropodborne. Yellow fever was the first human disease associated with a virus. It is passed from person to person via blood-sucking mosquitoes, Stegomyia aegypti. |
| Yellow fever symptoms | Primary symptoms of yellow fever are: abrupt headache, fever, muscle pain. Most patients recover after symptoms abate in 3-5 days. In some patients, the illness reappears as: Nausea, uncontrollable hiccups, black vomit, jaundice, delirium, hemorrhaging of the gums, mouth, and nose. 50% of patients enter a coma and die from internal hemorrhaging. Two vaccines are available, but no therapeutic drugs exist. |
| Dengue Fever | Occurs in four types. It is transmitted by two species of mosquito, S. aegypti and S. albopicta. Early signs of dengue fever include: high fever and prostration, then sharp pains and sensations like bones are breaking. Complications are unusual, unless one of the 3 other types of dengue fever enters the body later. In dengue hemorrhagic fever, the immune system allows the new infection to replicate. A rash from skin hemorrhages appear, followed by: severe vomiting and shock, decreased blood pressure. |
| HPS | Hantavirus pulmonary syndrome (HPS) occurs in the southwestern U.S. Classified as a bunyavirus, spread by infected animals. It is caused by a strain of hantavirus names "Sin Nombre." The deer mouse is the host, shedding the virus in saliva, urine, and feces. Humans are infected with hantavirus by inhaling dried, aerosolized urine or feces. Many patients suffer from: headaches, dizziness, difficulty breathing, low blood pressure. Respiratory failure can occur as the lungs fill with fluid. |
| Sandfly fever | Transmitted by sandflies of the genus Phlebotomus. Symptoms are similar to those of dengue fever including fever, headache, flu-like symptoms, muscle and joint pain. |
| Rift Valley Fever | Also affects livestock animals. It is transmitted by several genera of mosquitoes. Disease can be passed to humans. Symptoms are mild, fever, headache, muscle and joint pain; recovery in 2-7 days after onset. Small percentage can progress to hemorrhagic fever, meningoencephalitis. |
| Filoviridae | Members of the Filoviridae produce severe hemorrhagic lesions of the tissues. These include EHF (Ebola Hemorrhagic Fever) and MHF (Marburg hemorrhagic fever). |
| EHF | Ebola Hemorrhagic Fever has occasional outbreaks in Africa, causing 50-90% mortality. It appears to be zoonotic, with fruit bats as a possible reservoir. Transmission can occur with contact with blood or secretions from an infected person or contaminated objects. Symptoms- fever, headache, joint/muscle aches, sore throat, weakness. It damages endothelial cells, causing massive internal bleeding and hemorrhaging. |
| MHF | Marburg hemorrhagic fever was first identified in the tissues of green monkeys. Mode of transmission is unclear. Disease is spread by bodily fluids (blood, excrement, saliva, vomit). Symptoms are similar to EHF, but the fatality rate is lower. Early symptoms are non-specific with fever and after 5 days a maculopapular rash appears on the trunk. Late-stage includes jaundice, weight-loss, delirium, hemorrhaging, pancreatitis. |
| Lassa fever | Member of the Arenaviridae, associated with chronic infections in rodents. Lassa fever is caused by a zoonotic virus carried by rodents. It is transmitted through aerosol or direct contact with rodent excreta or contaminated food. Infection leads to: severe fever, exhaustion, patchy blood-filled hemorrhagic lesions of the throat. |
| Other hemorrhagic fevers and respective locations | 1) Congo-crimea hemorrhagic fever occurs worldwide. 2) Oropouche fever and Sabia virus affect regions of Brazil. 3) Junin and Machupo occur in Argentina and Bolivia, respectively. 4) Guanarito virus is associated with Venezuelan hemorrhagic fever. |
| Viral infections of the gastrointestinal tract | 1) Hepatitis Viruses A and E. 2) Viral Gastroenteritis. 3) Rotavirus. 4) Norovirus. 5) The Coxsackie virus. 6) The Echovirus. |
| Hepatitis Virus A | Hepatitis A is an acute inflammatory liver disease. Commonly transmitted by food or water contaminated by the feces of an infected individual (transmission can also occur by raw shellfish). Hepatitis A virus (HAV) belongs to the Picornaviridae family. Enlargement of the liver and jaundice may follow initial symptoms. High standards of personal and environmental conditions are needed to prevent transmission. Three vaccines are available for different age groups. There is no known treatment. |
| Hepatitis Virus B | An opportunistic, emergent disease. It is caused by a member of the Caliciviridae family. Young adults and pregnant women are most susceptible. |
| Viral Gastroenteritis | caused by several unrelated viruses. Viral gastroenteritis is a general name for illnesses involving: Diarrhea, nausea, vomiting, fever, cramping, headache, malaise. |
| Rotavirus infections | can be a deadly infection in children. Transmission occurs through ingestion of contaminated food or water. The viruses invade the small intestine, inducing diarrhea. Two vaccines are available. |
| Norovirus infections | a common cause of nonbacterial gastroenteritis in adults. Transmission occurs through: the fecal-oral route, direct person-to-person contact, contact with infected surfaces. Recent outbreaks have been seen on cruise ships. They are highly contagious; incubation 15-48 hours. Symptoms last 12-60 hours. Dehydration is the most common complication. Washing hands and safe food and water is only prevention. |
| Coxsackie virus | An enterovirus infection. Different strains of Coxsackie viruses cause gastroenteritis, as well as several other serious diseases. |
| Echovirus | also an enterovirus. It occurs in many strains. It can cause: Gastroenteritis, aseptic meningitis, exanthemas. |
| Viral diseases of the Nervous System | 1) Rabies virus (in humans and animals). 2) Polio virus. 3) Different flaviviruses. 4) West nile fever. 5) Lymphocytic Choriomeningitis. |
| Rabies Virus | Of great medical importance worldwide. It has the highest mortality rate of any human disease. Animal rabies occurs in warm-blooded animals. It enters the body through a skin wound contaminated with a bodily fluid from an infected animal. The incubation period varies from 6 days to 1 year (depends on the location of entry and amount of virus entering the body). |
| Rabies Symptoms | Fever, headache, and increased muscle tension develop. Patients become alert and aggressive, followed by paralysis and brain degeneration. Death from respiratory paralysis occurs within days. Post-exposure immunization can be done immediately after exposure. |
| Rabies in Animals | Furious rabies involves violent symptoms like: wide eyes, drooling, unprovoked attacks. Animals with dumb rabies are docile and lethargic. Wild animals are vaccinated with inoculated dog food and fish meal. |
| Polio Virus | May be the next infectious disease to be eradicated. Polio (poliomyelitis) infects the gray matter of the spinal cord and brain. Polioviruses enter the body through contaminated food and water. |
| Polio Progression | Polio viruses multiply in: Tonsils, lymph tissue, and gastrointestinal tract. Sometimes the viruses pass through the bloodstream to the meninges, which can result in paralysis of limbs and trunk. In bulbar polio, the viruses infect the medulla, affecting nerves in the: neck, face, and upper torso. Trivalent vaccines contain all 3 types of poliovirus. Post polio syndrome occurs in individuals who had the disease decades ago. |
| Flaviviruses | Different flaviviruses can be carried by blood-sucking arthropods. Encephalitis is an acute inflammation of the brain. Arboviral encephalitis patients suffer from: Pain in the head and neck, convulsions, and coma. Those who recover may have paralysis and mental disorders. There are many forms, many transmitted by mosquitoes and ticks. |
| West Nile Fever | an emerging disease in the Western hemisphere. It can infect birds, mosquitoes, humans, and some other mammals. Humans generally contract it through mosquito bites. Many infected people remain asymptomatic, or are ill for a few days. Rarely, the patient will develop encephalitis or meningitis, which can result in permanent neurological effects or death. There is no vaccine or specific treatment for West Nile Fever. |
| LCM | Lymphocytic Choriomeningitis is usually found in rodents. It can be transmitted to humans through urine and feces. Symptoms tend to be mild and influenza-like: fever, malaise, headache, drowsiness, stupor, and meninges infiltrated with large numbers of lymphocytes. Symptoms subside in a week. Low mortality rate. |
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