What is an infectious disease

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What is an infectious disease?

Works Cited

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What is an infectious disease? Well dictionary.com defines it as a disease caused by the entrance into the body of organisms (as bacteria, protozoans, fungi, or viruses) which grow and multiply there. It can enter the body through liquid, food, contaminated objects, and airborne inhalation, and vector born spread. Infectious diseases are massively numerous. How easy it is for someone to be infected is different for different people however compared to the sheer number of micro-organisms in the world the chances of a healthy individual getting infected are relatively small.

Infectious diseases are classified in quite a few different ways such as...

How long they last

Acute; occurs over a relatively short time period like a cold or the flu

Chronic; when the pathogen evades the immune system and persists in the body for months to years

How they are transferred

Horizontal; from individual to individual

Vertical;from parent to offspring

How long they have been around

Emerging; relatively new and still forming and changing

Re-Emerging; went away at some point in history and is now coming back

How many cases

Sporadic; occasional occurrence

Endemic; regular cases often occurring in a region

Epidemic; an unusually high number of cases in a region

Pandemic; a global epidemic

Image by Anthrax Vaccine Immunization Program Agency, Office of the Army Surgeon General, United States.


The fifth plague in the book of genesis is one of the earliest descriptions of anthrax. Anthrax is primarily a disease of herbivores. Natural incidence isn't very common, but infection is an occupational hazard among veterinarians, farmers, and individuals who handle animal wool, hair, hides, or bone meal products. Inhalation of anthrax may resemble the common cold or flu, which may later develop into a sudden drop in blood pressure, shock and difficulty breathing. Anthrax can be cured with antibiotics.


Botulism is a serious paralytic illness caused by a nerve toxin, botulin, which is produced by the bacterium Clostridium botulinum. Botulin is the most potent known toxin, blocking nerve function and leading to respiratory and musculoskeletal paralysis. All forms of botulism can be fatal and are considered medical emergencies. In the United States an average of 110 cases of botulism are reported each year. Of these, approximately 25% are food borne, 72% are infant botulism, and the rest are wound botulism. Botulin toxin or botox is the toxic compound produced by the bacterium Clostridium botulinum. It is an enzyme that breaks down one of the fusion proteins that allow neurons to release acetylcholine at a neuromuscular junction. By interfering with nerve impulses in this way, it causes paralysis of muscles

Rocky Mountain Spotted Fever (RMSF)

RMSF is a tick-borne disease caused by the organism"Rickettsia rickettsii". RMSF gets its name from the trademark rash it causes, small red spots and blotches, that begin on the wrists, ankles, palms, and soles. In addition to the rash, the infection can cause fever, chills, muscle aches, vomiting, and nausea. Without antibiotic treatment, RMSF can lead to health problems that involve the heart, lungs, and brain. In the most severe case, it can be deadly. Ticks become infected by feeding on the blood of infected animals, through fertilization, or by transovarial passage. Rickettsiae are transmitted from tick to human during feeding.

Strep Throat

Strep throat is caused by streptococcal (strep) bacteria. There are different types and some are more dangerous than others. Although some people are quick to think that any painful sore throat is strep, sore throats are usually caused by a viral infection and not strep bacteria. The most common symptoms of strep throat are: A sudden, severe sore throat, Pain when you swallow, Fever over 101F, Swollen tonsils and lymph nodes, white or yellow spots on the back of a bright red throat, a headache and belly pain, a red skin rash, vomiting, loss of appetite, and body aches. When a person who has strep throat breathes, coughs, or sneezes, tiny droplets with the strep bacteria go into the air. These droplets can be breathed in by other people. If you come into contact with strep, it will take 2 to 5 days before you start to have symptoms. Strep can easily be cured with antibiotics to where within 24 hours you are no longer contagious.

Rheumatic fever

Rheumatic fever is a complicated, involved disease that affects the joints, skin, heart, blood vessels, and brain, an inflammatory disease that may develop two to three weeks after strep. Acute rheumatic fever more commonly appears in children between the ages of 5-15, with only 1/5 of first time attacks occurring in adults. The symptoms of rheumatic fever are joint inflammation, small nodules or hard, round bumps under the skin, a change in your neuromuscular movements, a rash, fever, weight loss, fatigue, stomach pains. It is usually cured with antibiotics, anti-inflammatory, and lots of bed rest.

West Nile Virus (WNV)

West Nile virus is avirusof the familyFlaviviridae. Part of theJapanese encephalitisantigenic complex of viruses, it is found in bothtropicalandtemperateregions. It mainly infectsbirds, but is known to infecthumans,horses,dogs,cats,bats,chipmunks, skunks,squirrels, and domesticrabbits. The main route of humaninfectionis through the bite of an infectedmosquito. There is novaccinefor humans. A vaccine for horses based on killed viruses exists; somezooshave given this vaccine to their birds, although its effectiveness there is unknown. Dogs and cats show few if any signs of infection. There have been no known cases of direct canine-human or feline-human transmission; although these pets can become infected, it is unlikely that they are in turn capable of infecting native mosquitoes and thus continuing the disease cycle. There are however Studies of phylogenetic lineages that have determined that WNV emerged as a distinct virus around 1000 years ago. This initial virus developed into two distinct lineages, Lineage 1 and its multiple profiles is the source of the epidemic transmission in Africa and throughout the world, while Lineage 2 remains as an Africazoonose.(disease which can be transferred from animals to humans) The only cure for the WNV at the time is time, patience, and rest.


Meningitis is inflammation of the protective membranes covering the brain and spinal cord which are known as meninges. The most common symptoms of meningitis are headache, neck stiffness, fever, confusion or altered consciousness, vomiting, and an inability to tolerate light or loud noises. A lumbar puncture may be used to diagnose or exclude meningitis. In adults, a severe headache is the most common symptom of meningitis occurring in almost 9/10 cases. Meningitis is potentially life-threatening and has a high mortality rate if untreated. It is often cured with steroids or antibiotics. It is now thought to be caused by herpes simplex virus type 2(genital herpes).


HIV is a retrovirus (a virus that injects it's RNA into a cell and then that RNA replicates with the cell's DNA therefore making more infected cells). HIV uses human white blood cells as host bodies. The white blood cells that HIV uses as host cells are called CD4 T-lymphocytes, which are commonly called "CD4 cells" or "T-cells" for short. CD4 cells are used to fight infection and are a key element of the immune system. In the process of replication, HIV kills CD4 cells. By replicating and killing CD4 cells. An adult with a healthy immune system generally has a CD4 cell count of from 600 to 12001. At this point and time we can get HIV cell count down enough to not even show up on blood tests however the problem is HIV can easily mutate and evolve becoming resistant and tolerant to the drugs. With the continuation of this particular drug therapy, the rare resistant virus will continue to replicate and will eventually become dominant. At this point your virus has become resistant to one or more of the drugs in your drug therapy.

HIV is at this moment incurable, however we are actually getting very close to creating a cure from abzymes which are produced by lupus patients to cut parts of the HIV cells and this is passing every test so far with only the human test to go. All lab and animal tests passed greatly.

Drug resistance

Drug resistance is the reduction in effectiveness of a drug. Pathogens (what we call germs) are said to be drug-resistant when drugs meant to neutralize them have reduced effect. When an organism is resistant to more than one drug, it is said to be multidrug resistant. Drug resistance is an example of evolution in micro organisms. Individuals that are not susceptible to the drug effects and are capable of surviving drug treatment, therefore have greater fitness than susceptible individuals. By natural selection, drug resistant traits are selected for in subsequent offspring, resulting in a population that is drug resistant.


The flu, one of the most common heard of infectious diseases known to our society. Surely if you have paid attention at all to the news in your live you have heard of some sort of flu such as the H1N1 or avian flu. With every season people often going way out of their way to get a flu immunization shot made out of dead virus cells just so that they are less likely to become infected. The flu generally lasts 5-10 days. It is a very highly contagious disease that shouldn't be taken too lightly. You also shouldn't fall into the propaganda of the media. There are so many different strands of influenza that it is hard to keep up with. The flu mutates and evolves rather rapidly. Influenza results from infection with 1 of 3 basic types of influenza virus A, B, or C. A being the most common one. In 1997, an avian subtype of influenza A, H5N1, was first described in Hong Kong. Infection was confirmed in only 18 individuals, but 6 died. Since then, sporadic cases of H5N1 infection have continued to be described. On April 26, 2009, the US Department of Health and Human Services issued a nationwide public health emergency regarding swine influenza A (H1N1) virus infections in humans.1 Over the preceding several weeks, an outbreak of a new strain of influenza virus, which contains a combination of swine, avian, and human influenza virus genes, had been reported in Mexico and in the United States. H1N1 influenza had infected 28,774 people in 74 countries, and 144 deaths were confirmedby late June 09. The flu kills about 20,000 people each year. Flu symptoms can be mild or severe and if they're mild can become severe without much notice. The common symptoms of the flu include Fever, Headache Muscle aches, Chills, Extreme tiredness, Dry cough, Runny nose, Stomach symptoms, such as nausea, vomiting, and diarrhea. The flu can only be treated and not cured.


Smallpox is an acute contagious disease caused by the variola virus. Smallpox localizes in small blood vessels of the skin and in the mouth and throat. During the 20th century, it is estimated that smallpox was responsible for 300-500 million deaths. So it is a very dangerous disease. To this day, smallpox is the only human infectious disease to have been completely eradicated. You contracted the virus by inhalation making it very contagious, With symptoms such as flu like symptoms, muscle & joint pain, chickenpox type rash and many other unpleasantness. And interesting thing about small pox is The British considered using smallpox as a biological warfare agent during the French and Indian Wars (1754-63), against France and its Native American allies at the Siege of Fort Pitt.

Herpes virus

Herpes is literally translated as "creeping" which is kind of true about the virus. Herpes is a viral disease caused by both herpes simplex virus 1 (HSV-1) (oral herpes such as cold sores) and herpes simplex virus 2 (HSV-2) (genital herpes). Herpes viruses cycle between periods of active disease presenting as blisters containing infectious virus particles that last 2 to 21 days, followed by a remission period, during which the sores disappear. Herpes simplex is most easily transmitted by direct contact with a lesion or the body fluid of an infected individual. Transmission may also occur through skin-to-skin contact during periods of asymptomatic shedding.