Microbiology (Viruses)

Infectious mononucleosis

DNA Virus Epstein-Barr Virus Like cytomegalovirus, it is transmitted in secretions. Therefore it is a contact disease, often called the kissing disease because it is frequently found in the college-age population. By mid-life, 90% of people have had it. In children it is not severe. In adolescents it is a sore throat, high fever, cervical lymphadenoathy with accompanying fatigue. Can last a long time. If contracted as an adult can go to the brain and casue an encephalitis.

Herpes simplex I

DNA Virus Herpes simplex Causes lesions on face, usually around mouth. Can go away and come again (latent). Transmitted by contact. When virus goes away it travels back to the central nervous system at the base of the brain. HSV-1 goes to 5th cranial nerve. Can cause severe disease of newborn that can result in death.

Herpes simplex II

DNA Virus Herpes simplex Similar to HSV-1 except that his is a disease of the genitalia. When the virus disappears, it goes not to the brain, but to the lumbosacral spinal nerve trunk ganglia. Episodes of this and HSV-1 are triggered by stress, both physical and emotional. Can be transmitted to newborn and may result in death.

Canine Herpesvirus

DNA Virus Herpesvirus Causes fatal hemorrhagic disease in puppies less than three weeks old. Puppies get the disease as the pass through birth canal. Virus infects nasal mucosa and spreads, casuging a necrotizing vasculitits that results in hemorrhaging around the blood vessel. Fatality rate is 80%.

Shingles

DNA Virus No.Varicella-Zoster see chicken pox

Papillomavirus

DNA Virus Papillomavirus More than 100 different strains of human papillomavirus. Transmitted through direct contact or contaminated fomites. Causes warts. They often go away, but sometimes have to be removed. For genital warts, it is considered a sexually transmitted disease. Nine of the human papillomavirues increase the risk for developing cancer. A Pap smear will detect the formation of metastatic cells. In addition to genital warts, therer are also plantar warts (very painful) and common seed warts. There is a vaccine available for the genital wart viruses.

Fifth Disease (eythema infectiosum)

DNA Virus Parvovirus Causes rashes in chilren. A very mild disease. The symptom is called the "slapped-cheek" appearance because that is what it lookls like. Rash spreads but is most prominenet on the arms, legs and trunk. The rash may reoccur for several weeks and may be brought on by stress, exercise, fever, sunlight and emotion.

Hepatitis B

DNA Virus U.S. World Hepadnavirus One of the ten most common diseases in the U.S. Virus multiplies exclusively in the liver. It is transmitted by intimate contact (blood) and so is typically transmitted by sex or drug use. Because it affects the liver, it increases the chance of liver cancer. Symptoms include malaise, fever, chills, anorexia, abdominal discomfort and diarrhea. In severe cases there is jaundice, a rash, and arthritis. A small number of individuals develop chronic liver disease.

Parvovirus

DNA Virus Zoonotic. Parvovirus Causes distemper in cats, enteric disease in dogs, and a fatal cardiac infection in puppies. A few of the parvovirus strains can cause infections in humans.

Canine Distemper

DNA Virus. Parmyxovirus Spread through aerosol droplets and contact with bodily fluids. Puppies are particularly susceptible. It affects raccoons, wolves, foxes and skunks; and ferrets can carry the virus. It first attacts lymph nodes and then spreads to respiratory, urogenital, gastrointestinal, and nervous systems. High fever, reddened eyes and watery discharge from nose and eyes. Dog will become lethargic and tired with persisten coughing, vomiting and diarrhea in later stages. Fatality rate can reach 50%.

Smallpox (variola major)

DNA Virus. U.S. Variola major Contracted by inhalation or skin contact. Variola major is the highly virulent form of poxvirus. Starts with fever, discomfort, headache, severe fatigue, back pain and sometimes vomiting/diarrhea. The a few days later come the pocks. Usually they leave scars. Fatality rate used to be 30%. With supporting treatment survival is much higher. Using an aggressive vaccination program, smallpox has been largely eradicated from the world

Adenovirus respiratory tract infections

DNA virus Adenovirus. This is a major cause of Upper Respiratory Tract Infection. Colds, pharyngitis, conjunctivitis. Easily spread by respiratory secretions. Severe cases are treated with interferon.

Avian Influenza

RNA Virus Can be, it depends on the strain. Influenza Highly contagious between chickens. Spread by nasal secretions in a flock. Fatality can reach 100%. If Avian influenza is found in a flock generally the entire flock is sacrificed to prevent the spread.

Feline Immunodeficiency

RNA Virus Feline immunodeficiency virus Weight loss, poor cat coat condition, anemia, gastroenteritis, gingivitis, diarrhea, chronic infections, cancer

Influenza B

RNA Virus Orthomyxovirus Does not change genetically as much, so it is not as much of a problem.

Influenza C

RNA Virus Orthomyxovirus Only causes minor respiratory disease

Pseudorabies

RNA Virus Suid herpesvirus Most economically important disease of swine in areas where hog cholera has been eradicated. Other domestic animals are susceptible. It is usually fatal in these hosts. Spread by oral or nasal contact. Swine are often assymptomatic, but can cause abortion, high mortality in piglets, coughing, sneezing and constipation. Mortality in piglets less than 1 month old is close to 100%. In cattle symptoms include intense itching followed by neurological signs and death. In dogs symptoms include intnese itching, howling, and death. In cats, the disease is so rapidly fatal that no symptoms are noted.

AIDS

RNA Virus U.S. & WORLD. Human Immunodeficiency Virus (HIV) The CD4 receptor on white blood cells is the key. Transmission by blood products (sexual intercourse and needles). It destroys your immune system and you die from secondary infections like pneumonia or certain cancers. Used to be an epidemic in the U.S. but is now controlled by drug therapy that keeps the virus in check. Still a problem worldwide where more than 30 million people are infected. It is a relatively slow infection and after an initial mono-like disease may go away for 2-15 years. It gradually kills your immune system and patients start to have odd infections. When CD4 T cells fall below 100 per microliter, you are in trouble.

Calicivirus diarrhea (Norwalk Agent)

RNA Virus U.S. Calicivirus Norwalk Agent of Norovirus. Acute onset nausea, vomiting, cramps, diarrhea and chills. May cause as much as one third of all gastroenteritis cases. Transmitted by fecal oral. It received its name from being identified as a disease in Norwalk, Connecticut.

Severe Acute Respiratory Syndrome

RNA Virus U.S. Coronavirus Coronaviruses are common in domestic animals. Transmitted by air and droplests. This is a new disease. Causes respiratory distress and one in ten people die. Supportive treatment.

Mumps

RNA Virus U.S. Paramyxovirus Starts upper respiratory then goes to secondary sites. Usually parotid salivary glands and sometimes testes. Only 300 cases per year in U.S. because we have a vaccine MMR.

Polio

RNA Virus U.S. Picornavirus An acute enteritis virus gone wrong because it gets to your CNS in a small number of cases. Can cause paralysis. One of the first diseases for which we had a vaccine. Transmitted by fecal-oral. Starts in upper respiratory tract and moves on. Most infections are not serious. Can cause post-polio syndrome - progressive muscle deterioration.

Respiratory Syncytial Virus

RNA Virus U.S. Pneumovirus URT disease. Diagnosed by symptoms and giant multinucleate cells. Most prevalent cause of respiratory disease in children 6 months or younger. Can be serious. Also called Pneumovirus

Rubella

RNA Virus U.S. Rubivirus German measles. Transmitted through salivary secretions. Mostly in adolescents and young adults. Is not serious in adults, but when pregnant in first trimester can cause miscarriage or birth defects.

Chickenpox

RNA Virus U.S. Varicella-Zoster Easily transmitted by respiratory secretions. A mild flu-like disease with characteristic rash (vesicles). It can enter neurons and be reactivated later in life as shingles. A a skin disease that can cause severe pain and discomfort.

Hepatitis C

RNA Virus U.S. WORLD. Flavivirus Liver disease usually acquired through blood contact (transfusions, needle sharing, etc). Usually a chronic liver infection, but may progress to cancer.

Measles

RNA Virus U.S. WORLD. Morbillivirus URT disease. Sore throat, cough, headache, Koplik spots. A rash. Not generally serious, but can have sequel of subacute sclerosing panencephalitis (SSPE) which causes death by neurodegeneration. Only once in a million cases of measles. We have MMR vaccine for measles.

Hepatitis A

RNA Virus U.S. WORLD. Picornavirus Resistant to stomach acid, transmitted fecal-oral. Most infections subclinical, but may feel like mild flu. Jaundice not usually present. Vaccine is available.

Rotavirus diarrhea

RNA Virus U.S. WORLD. Rotavirus Oral-fecal transmission. Any baby/child that dies from a severe diarrheal disease .... One of the top 15 most common communicable diseases in the U.S.

Influenza A

RNA Virus U.S. WORLD. ZOONOTIC. (some strains) Orthomyxovirus Of A, B, and C, this is the one that causes the most illnesses. It changes every year because human influenza and fowl influenza get genetically mixed in swine (segmented genome). This is in the list of top 15 causes of death in the U.S.

Yellow Fever

RNA Virus U.S. WORLD. ZOONOTIC. Flavivirus Acute fever, headache, muscle pain. May progress to hemorraging and liver and kidney damage. A significant mortality rate. A real problem in building the Panama Canal. Transmitted by mosquito.

Eastern Equine Encephalitis

RNA Virus U.S. ZOONOTIC. Arbovirus These viruses replicate in the vector (usually a mosquito) but they do not hurt it. The mosquito transfers the virus from on individual to another by biting the first, sucking blood that contains the virus, and then biting another individual. Control of arboviruses is often centered on control of mosquitoes. The arboviruses are a diverse group, but most of the ones in this category are members of the subfamily alphaviridae and they cause encephalitis. Eastern Equine Encephalitis is of major concern to the horse industry because it can rapidly move through a herd. The horse becomes sick 1-3 weeks after infection. Eventually brain lesions appear, causing drowsiness, drooping ears, circling, aimless wandering, inability to swallow and abnormal gait. Paralysis follows, causing the horse to have difficulty raising its head. The horse usually dies within 4 days of exhibiting symptoms. Fatality rate in horses is around 80%. Human symptoms for this disease (gotten not from the horse but a mosquito) include high fever, muscle pain, altererd mental status, headache, photophobia and seizures. These occur 3-10 days after the bite of an infected mosquito. There is not treatment other than supportive therapy.

Hantavirus Pulmonary Syndrome

RNA Virus U.S. ZOONOTIC. Bunyaviruses Often fatal disease that we did not even know about until 1993. Starts with flu-like symptoms such as fever, cough, myalgia, headache and lethargy. Then there is a sudden onset of shortness of breath with rapidly evolving pulmonary edemat that is often fatal despite mechanical ventilation. Fatality rate is 60%. It is contracted from rodent feces, so control of the disease is by control of the rodent population in an area.

St. Louis Encephalitis

RNA Virus U.S. ZOONOTIC. Flavivirus Fairly common encephalitis in the U.S. More than 4,000 cases reported between 1964 and 1998. Most were in Illinois, Indiana and Ohio. Mild illness with fever and headache. In severe infection may experience high fever, neck stiffness, stupor, disorientation coma, tremors, occasional convulsions and spastic paralysis. Fatality is in the 3-30% range with elderly folks being the most likely to have a fatal infection.

West Nile Virus

RNA Virus U.S. ZOONOTIC. Flavivirus This has been known to exist in Uganda, Africa for quite a while. But in the last 10 years it has moved to be a world-wide disease. It is transmitted by mosquitoes. 80% of West Nile infections are subclinical. When symptoms do occur, they are fever, headaches, fatigue, muscle pain, malaise, nausea, anorexia, vomiting, myalgias and rash. Less than 1% of the cases are severe and result in neurological disease Once again, it is the very young, the elderly, and the immunosuppressed that are at highest risk. We control the disease by controlling the mosquito population.

Rabies

RNA Virus U.S. ZOONOTIC. Rhabdovirus Bullet-shaped virus. Very slow growing and developing. So slow that you can be immunized after you are bitten by a rabid animal. Has prodromal, furious, dumb, and death phase. Know each one. It is a neurological disease. Diagnosed by Negri bodies. Spread by a number of wild and domestic mammals.

Japanese encephalitis

RNA Virus WORLD. Flavivirus Japanese encephalitis (JE) virus is the leading cause of vaccine-preventable encephalitis in Asia and the western Pacific. For most travelers to Asia, the risk for JE is very low but varies based on destination, duration of travel, season, and activities. JE virus is maintained in a cycle involving mosquitoes and vertebrate hosts, mainly pigs and wading birds. Humans can be infected when bitten by an infected mosquito. Most human infections are asymptomatic or result in only mild symptoms. However, a small percentage of infected persons develop inflammation of the brain (encephalitis), with symptoms including sudden onset of headache, high fever, disorientation, coma, tremors and convulsions. About 1 in 4 cases are fatal.

Dengue Fever

RNA Virus WORLD. ZOONOTIC. Flavivirus Carried by mosquito. Causes hemorrhagic fever, muscle and joint pain, and can be fatal. It isnormally considered to be a disease of Central America (that's where the mosquitoes are) but as the mosquitoes are moving north so is Dengue. There are cases reported in southern Texas.

Ebola

RNA Virus Zoonotic. Filovirus Highly virulent. Highly fatal. Transmitted by contact. Case fatality rate as high as 90% for some strains. A disease of Africa, first noted around the Ebola river. Sudden onset of flu-like symptoms - malaise, fever with chills, arthralgia, myalgia, chest pain. Nausea accompanied by adbdominal pain, anorexia, diarrhea, and vomiting. Respiratory tract involvement with sore throat, cough, dyspnea and hiccups. CNS involvement includes severe headaches, agitation confusion fatigue, depression seizures and sometimes a coma. Also may have skin involvement with maculopapular rash, petechia, purpura, ecchymoses and hematomas. Basically, every tissue of your body is affected. Death is typically due to multiple organ dysfunction. This disease appeared in about 1976 and we have yet to understand where it came from. The best current guess is that is caught from bats in the region.

Arenaviruses

RNA Virus Zoonotic. several viruses These are typically carried by rodent hosts and transmitted through aerosol or contact. The more serious of these cause Hemorrhagic fever. For the most part, these are issues in the world, not the U.S. Bolivian Hemorrhagic fever, Venezuelan hemorrhagic fever, Lassa fever (Africa), and Brazilian hemorrhagic fever. Characteristically, the overall vascular system is damaged, and the body's ability to regulate itself is impaired. These symptoms are often accompanied by hemorrhage (bleeding); however, the bleeding is itself rarely life-threatening. While some types of hemorrhagic fever viruses can cause relatively mild illnesses, many of these viruses cause severe, life-threatening disease.

Hog cholera (Classical swine fever)

Virus Flavivirus Strength of disease depends on virulence of virus. Less virulent strains may be subacute or chronic, but still cause stillbirths and abortions. Highly virulent strains cause neurological signs and hemorrhaging.Fatality rate in piglets is near 100%. There is not treatment other than slaughter to prevent spread. A vaccine is available and will be administered if there is Hog cholera in the region.