An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease. Colloquially, infections are usually considered to be caused by microscopic organisms or microparasites like viruses, prions, bacteria, and viroids, though larger organisms like macroparasites and fungi can also infect.

Hosts normally fight infections themselves via their immune system. Mammalian hosts react to infections with an innate response, often involving inflammation, followed by an adaptive response. Pharmaceuticals can also help fight infections.

The branch of medicine that focuses on infections and pathogens is infectious disease medicine.

Diagnostic approach

Diagnosis of infections can be difficult as specific signs and symptoms are rare. If an infection is suspected, blood, urine and sputum cultures are usually the first step. Chest x-rays and stool analysis may also aid diagnosis. Spinal fluid can be tested to ensure that there is no brain infection.

In children the presence of cyanosis, rapid breathing, poor peripheral perfusion, or a petechial rash increases the risk of a serious infection by greater than 5 fold. Other important indicators include parental concern, clinical instinct, and temperature greater than 40 °C. It's important to distinguish, because viral infections cannot be cured by antibiotics.

{|class="wikitable" |+Comparison of viral and bacterial infection |- ! Characteristic ! Viral ! Bacterial ! Internal Hurting |- || Typical symptoms | In general, viral infections are systemic. This means they involve many different parts of the body or more than one body system at the same time; i.e. a runny nose, sinus congestion, cough, body aches etc. They can be local at times as in viral conjunctivitis or "pink eye" and herpes. Only a few viral infections are painful, like herpes. The pain of viral infections is often described as itchy or burning. The chain of events involves several steps which include the infectious agent, reservoir, entering a susceptible host, exit and transmission to new hosts. Each of the links must be present in a chronological order for an infection to develop. Understanding these steps helps health care workers target the infection and prevent it from occurring in the first place.

Colonization

Infection begins when an organism successfully colonizes by entering the body, growing and multiplying. Most humans are not easily infected. Those who are weak, sick, malnourished, have cancer or are diabetic have increased susceptibility to chronic or persistent infections. Individuals who have a suppressed immune system are particularly susceptible to opportunistic infections. Entrance to the host generally occurs through the mucosa in orifices like the oral cavity, nose, eyes, genitalia, anus, or open wounds. While a few organisms can grow at the initial site of entry, many migrate and cause systemic infection in different organs. Some pathogens grow within the host cells (intracellular) whereas others grow freely in bodily fluids.

Wound colonization refers to nonreplicating microorganisms within the wound, while in infected wounds replicating organisms exist and tissue is injured. All multicellular organisms are colonized to some degree by extrinsic organisms, and the vast majority of these exist in either a mutualistic or commensal relationship with the host. An example of the former would be the anaerobic bacteria species which colonize the mammalian colon, and an example of the latter would be the various species of staphylococcus which exist on human skin. Neither of these colonizations would be considered infections. The difference between an infection and a colonization is often only a matter of circumstance. Organisms which are non-pathogenic can become pathogenic given specific conditions, and even the most virulent organism requires certain circumstances to cause a compromising infection. Some colonizing bacteria, such as Corynebacteria sp. and viridans streptococci, prevent the adhesion and colonization of pathogenic bacteria and thus have a symbiotic relationship with the host, preventing infection and speeding wound healing.

The variables involved in the outcome of a host becoming inoculated by a pathogen and the ultimate outcome include:

* the route of entry of the pathogen and the access to host regions that it gains

the intrinsic virulence of the particular organism

the quantity or load of the initial inoculant

the immune status of the host being colonized

As an example, the staphylococcus species present on skin remain harmless on the skin, but, when present in a normally sterile space, such as in the capsule of a joint or the peritoneum, will multiply without resistance and create a huge burden on the host.

Disease

Disease can arise if the host's protective immune mechanisms are compromised and the organism inflicts damage on the host. Microrganisms can cause tissue damage by releasing a variety of toxins or destructive enzymes. For example, Clostridium tetani releases a toxin which can paralyze muscles, or staphylococcus releases toxins which can produce shock and sepsis. Not all infectious agents cause disease in all hosts. For example less than 5% of individuals infected with polio develop disease. On the other hand, some infectious agents are highly virulent. The prion causing mad cow disease and Creutzfeldt–Jakob disease kills almost all animals and people that are infected.

Persistent infections occur because the body is unable to clear the organism after the initial infection. Persistent infections are characterized by the continual presence of the infectious organism often as latent infection with occasional recurrent relapses of active infection. There are some viruses that can maintain a persistent infection by infecting different cells of the body. Some viruses once acquired never leave the body. A typical example is the herpes virus which tends to hide in nerves and become reactivated when specific circumstances arise. Persistent infections cause millions of deaths globally each year. Chronic infections by parasites account for a high morbidity and mortality in many underdeveloped countries.

===Primary and secondary infections=== Primary and secondary infection may either refer to succeeding infections or different stages of one and the same infection such as in acute herpes labialis infection. In the latter case, acute infection may also be used, as in acute HIV infection.

Transmission

In order for infecting organisms to survive and repeat the cycle of infection in other hosts, they (or their progeny) must leave an existing reservoir and cause infection elsewhere. Transmission of infections can take place via many potential routes. Infectious organisms may be transmitted either by direct or indirect contact. Direct contact occurs when an individual comes into contact with the reservoir. This may mean touching infected bodily fluids or drinking contaminated water or being bitten by the deer tick. Direct contact infections can also result from inhalation of infectious organisms found in aerosol particles emitted by sneezing or coughing. Another common means of direct contact transmission involves sexual activity - oral, vaginal or anal sex.

Indirect contact occurs when the organism is able to withstand the harsh environment outside the host for long periods of time and still remain infective when specific opportunity arises. Inanimate objects that are frequently contaminated include toys, furniture, door knobs, tissue wipes or personal care products from an infected individual. Consuming food products and fluid which have been contaminated by contact with an infecting organism is another case of disease transmission by indirect contact.

A common method of transmission in under developed countries is fecal-oral transmission. In such cases, sewage water is used to wash food or is consumed. This results in food poisoning. Common pathogens which are transmitted by the fecal-oral route include Vibrio cholerae, Giardia species, rotaviruses, Entameba histolytica, Escherichia coli, and tape worms. Most of these pathogens cause gastroenteritis.

All the above modes are examples of horizontal transmission because the infecting organism is transmitted from person to person in the same generation. There are also a variety of infections transmitted vertically - that is from mother to child during the birthing process or fetal development. Common disorders transmitted this way include AIDs, hepatitis, herpes, and cytomegalovirus

Persistent viral infections

Many individuals develop a variety of infections in their lifetime, but quickly overcome them. However, some individuals develop chronic or persistent infections. In the majority of cases, persistent infections are caused by viruses and not bacteria. The common viruses that can cause chronic infection include measles, hepatitis, herpes, infectious mononucleosis and Cytomegalovirus (CMV). Bacteria can also cause chronic infections in individuals with diabetes, those with compromised immunity and in individuals who smoke.

The most common persistent infections in North America include HIV, hepatitis, herpes simplex and common to all mammals endogenous retroviruses which play crucial role in placentation and therefore act as symbionts. Hepatitis B and C are usually acquired from use of dirty needles, blood transfusions or sexual intercourse. HIV has similar modes of transmission. Once hepatitis has been acquired, it becomes a chronic disorder. While some individuals with hepatitis B may remain asymptomatic, many will show active symptoms and remain infectious. In the long term, both hepatitis B and C can cause liver failure or induce liver cancer. In some cases, the signs and symptoms of liver damage may not appear for 20 years after the infection was initially acquired. Other persistent infections include recurrent ear infection in children, tuberculosis, Lyme disease, Chlamydia and malaria. The problem with recurrent infections is that the organism continues to damage the body which eventually results in symptoms. As the body weakens, the individual develops weight loss and extreme fatigue.

Some examples of infections

Specific bacterial infections

H pylori is associated with inflammation of the stomach and is a common cause of stomach ulcers and gastritis. At least 10 percent of individuals infected with h pylori develop an ulcer. Moreover, there is an increased risk of stomach cancer after an infection with this organism.

Methicillin-resistant staphylococcus aureus predominantly affects the skin and is considered to be a super bug as it is very resistant to antibiotics. This bacteria is known to generate a variety of toxic enzymes which can lead to vomiting, diarrhea, shock and sepsis. MRSA is quite common in hospitals and today there is a great cause for concern about its spread.

Chronic ear infections

Chronic ear infections are a common problem in childhood. These infections may be due to bacteria or the common cold virus. The disorder often presents with persistent blockage of the ear, hearing loss, chronic ear drainage, balance problems, deep ear pain, headache, fever, excess sleepiness or confusion. Chronic ear infections usually develop slowly over many years in patients who have had ear problems. The treatment of persistent ear infections is complex and requires a combination of antibiotics, corticosteroids, and/or placement of tubes. When this fails surgery is required to control the infection.

Osteomyelitis

Osteomyelitis is a bone infection caused by various bacteria and can occur in both children and adults. When bone gets infected, there is continuous pain, fever and it is painful to move the extremity. Bone infections are acquired from an infection elsewhere in the body, trauma or spread from adjacent infected tissues. The diagnosis of bone infection requires a bone scan, blood cultures and x rays. Sometimes the bone marrow is aspirated to discover the specific organism. Osteomyelitis is a serious infection and carries a high complication rate if not treated promptly. If the infection is diagnosed rapidly, the prognosis is good. However chronic Osteomyelitis can take years to heal and can keep on recurring. Individuals at risk for Osteomyelitis include those who have artificial joints or metal components in the joint.

Lyme disease

Lyme is a tick borne disease that can cause a skin rash, fever, chills, body aches and joint pain. Some individuals even develop severe weakness and temporary paralysis. Lyme disease is caused by at least three species of bacteria belonging to the genus Borrelia, which are carried by deer ticks. One is more likely to get the infection during the summer months, especially if one spends time in grassy woodlands where the tick breeds. When the infection is diagnosed promptly, most people do recover fully. However, there are some individuals who keep on having recurring or lingering symptoms long after the infection has been treated. Lyme disease when it becomes chronic can present with a variety of symptoms including migrating joint pains, headaches, confusion, excess fatigue, inability to sleep, paralysis of one side of the face and difficulty concentrating. Even though there are reliable tests available they are not one hundred percent sensitive. While most individuals do respond to a 14 day course of antibiotics, some individuals take a lot longer.

Chlamydia

Chlamydia is a common sexually transmitted disease which can damage the female sex reproductive organs if not treated promptly. Chlamydia can silently damage the reproductive organs which can result in permanent infertility. Chlamydia is the most frequently sexual transmitted bacterial infection in America. The organism is also transmitted orally and through anal sex. Chlamydia is also known as the silent disorder because many women who acquire this infection have no symptoms. Those who develop symptoms may complain of low back pain, painful intercourse, nausea, fever, bleeding, lower abdominal cramps, and a discharge. When diagnosed Chlamydia can be treated with antibiotics. However, women whose sex partners are not treated are at a very high risk for re infection. Moreover, multiple infections increase the female's chances of damaging their reproductive organs resulting in infertility

Occult infection

An occult or asymptomatic infection is medical terminology for a "hidden" infection, that is, one which presents no symptoms. Dr. Fran Giampietro discovered this type, and coined the term "occult infection" in the late 1930s.

Treatment and prevention

Viable treatment and prevention strategies will disrupt the infection cycle. For example, direct transmission can be diminished by adequate hygiene, maintaining a sanitary environment as well as health education.

"When infection attacks the body, anti-infective drugs can suppress the infection. Four types of anti-infective or drugs exist: antibacterial (antibiotic), antiviral, antitubercular, and antifungal. Depending on the severity and the type of infection, the antibiotic may be given by mouth, injection or may be applied topically. Severe infections of the brain are usually treated with intravenous antibiotics. Sometimes, multiple antibiotics are used to decrease the risk of resistance and increase efficacy. Antibiotics only work for bacteria and do not affect viruses. Antibiotics work by slowing down the multiplication of bacteria or killing the bacteria. The most common classes of antibiotics used in medicine include penicillin, cephalosporins, aminoglycosides, macrolides, quinolones and tetracyclines.

Techniques like hand washing, gowning and wearing face masks can help prevent infections from the surgeon to the patient or vice versa. Frequent hand washing remains the most important factor in preventing spread of non wanted organisms. Nutrition has to be improved and one has to make changes in life style- like avoiding use of illicit drugs, using a condom and entering an exercise program. Cooking foods well and avoiding eating foods which have been left outside for a long time is also important. Do not take antibiotics for longer than needed. Long term use of antibiotics leads to resistance and chances of developing opportunistic infections like clostridium difficile colitis. Vaccination is another means of preventing infections by facilitating the development of immune resistance in vaccinated hosts.

See also

Antiseptic

Autoinfection

Hand infection

List of infectious diseases

Infectious disease

Multiplicity of infection

Ubi pus, ibi evacua (Latin: "where there is pus, there evacuate it")

Routes of infection

Infection control

Opportunistic infection

References

External links

Vaccine Research Center Information concerning vaccine research clinical trials for Emerging and re-Emerging Infectious Diseases.

Infection Information Resource

Knowledge source for Health Care Professionals involved in Wound management www.woundsite.info

Category:Infectious diseases

Coordinates	37°46′45.48″N122°25′9.12″N
Name	Chihiro Onitsuka
Background	solo_singer
Born	October 30, 1980
Origin	Nango, Miyazaki, Japan
Instrument	Piano
Genre	Folk, folk-rock
Occupation	Singer, songwriter
Years active	2000–present
Label	Toshiba EMI/Virgin Tokyo Universal Sigma/A&M; Records
Url	onitsuka-chihiro.jp

(born October 30, 1980) is a Japanese singer-songwriter.

In 2000, Onitsuka released her debut single "Shine" and gained a recognition with its follow-up "Gekkou" which became a hit. Insomnia, her first studio album released in following year topped the Japanese Oricon chart and sold more than a million copies. "Memai", one of the singles from her debut album provided her with honor of winning the prize for lyrics of the 43rd Japan Record Awards in 2001.

During her career, Onitsuka has repeatedly brought about troubles that are mostly owing to her physical problem and mental instability. She had put recording career on hold until March 2007, after some confrontations with record labels and management offices during the mid 2000s.

Onitsuka has enjoyed a successful career as one of the most popular Japanese female solo artists during the early 2000s. As of 2009, Onitsuka has released 5 studio albums, 17 singles, 2 compilations and several DVDs, which has sold at least 4.1 million.

Early life

Her parents encouraged Onitsuka to listen to Western music and by the time she was ten, she wrote her first poems, receiving praise from her parents, friends and teachers, who called them 'earnest efforts'. Secretly, however, she knew that just writing 'earnestly' wasn’t enough. From that time onward, she tried to write every day, and by the time she was in junior high school, she began to gain more confidence.

Having been influenced by Alanis Morissette in junior high school days, it was the encounter with Jewel’s music and presence during the high school years that strongly compelled Onitsuka to become a singer-songwriter. With some 70 original compositions and several other auditions under her belt, Onitsuka entered the 1998 Virgin Tokyo Artists Audition, going on to winning Grand Prize. Then only 17, Onitsuka started her career as a professional and moved to Tokyo in spring 1999 after graduating from high school.

Career

Rising to fame; "Gekkou" and Insomnia (2000-2001)

Chihiro Onitsuka's debut single "Shine" was released on March 2, 2000, under the Virgin Tokyo label which was distributed by the Toshiba EMI. A song was not successful and failed to chart, but soon after she gained a recognition with its subsequent single "Gekkou."

"Gekkou," a song that led Onitsuka to stardom, was initially featured as the closing theme for Trick, the successful TV drama series starring Yukie Nakama and Hiroshi Abe and aired on TV Asahi. A song was later released as a second single for her in August 2000. It debuted at #30 on the Japan's Oricon, and remained on the chart for 10 months. "Gekkou" has been her most commercially successful song to date, peaking at #11 on the charts and selling in excess of 500,000 copies.

In March 2001, the first studio album for Onitsuka entitled Insomnia was released. The album includes her signature song "Gekkou" and two follow-up singles "Cage" and "Memai"/"Edge" (the latter was released as a double A-Side), and newly recorded version of her debut single "Shine." The entire album features relatively minimum sound production by the producer Takefumi Haketa, and such acoustic-oriented arrangements symbolized her later works too. Insomnia debuted at the number-one on the Japanese Oricon album chart with the sales of over 400,000 copies, and selling more than 1.3 million units by the end of following year. It made her the second youngest female solo artist to have number-one album on the Oricon at the time, trailing Hikaru Utada whose debut album topped the chart at the age of 16. Onitsuka was awarded The Best Lyrics Award for "Memai" at The Japan Record Award (December 2001) and Rock Album Of The Year for album "Insomnia" at The Japan Gold Disc Award (March 2002).

2001-2003: Subsequent works

After the release of the first DVD/video Me And My Devil, a collection of her video clips, Onitsuka went on her first tour Chihiro Onitsuka Live Tour 2001. She then appeared at various rock festivals across Japan in summer of 2001. She was only accompanied by a piano on stage at the festivals full of famous rock bands.

While Insomnia album remained on the chart, she released a followed double A-Side single "Infection"/"Little Beat Rifle" in September 2001. A lead-off track "Infection" was featured as a theme song for Hyouten, a remake version of famous television drama based on same-titled novel written by Ayako Miura. However, owing to the part of its lyrics coincided with September 11 attacks occurred in the U.S., "Little Beat Rifle" was prioritized for promotion instead, to avoid causing controversy.

The release of the first live DVD/video Cradle On My Noise followed in November 2001.

2001 also saw Onitsuka’s music travel overseas. "Innocence" from her first album Insomnia was used in the soundbed of the TV campaign for Applied Materials based in Silicon Valley. The TV campaign aired on different channels including CNBC and CNN, resulting in many phone calls from the viewers asking who the singer was that they heard on the TV spot. Also, her song "Rasen" was used in the Luc Besson film Wasabi starring Jean Reno and Hirosue Ryoko.

Her second studio album This Armor was released in March 2002. It contains singles "Infection" and "Ryuseigun" which was featured as a theme song for a sequel of Trick drama series. It also includes remake versions of her previous efforts such as "Arrow of Pain" (originally released as a B-Side of "Gekkou") and "Little Beat Rifle" (double A-Side of "Infection").

Shortly after This Armor album came out, Onitsuka embarked on her second concert tour entitled Live Vibe 2002. But she fell gastroenteritis because of overwork during the tour, and postponed 2 shows to be held at Osaka and Sendai. During the concert, she sang several new songs from her third studio album Sugar High which was released only 9 months after its predecessor and debuted at the number-two on the charts.

Onitsuka released three singles in 2003, though those were less successful compared to her early efforts.Her seventh single "Ii Hi Tabidachi, Nishi e" is one of a few materials Onitsuka herself did not write. It was remake of a hit tune "Ii Hi Tabidachi" recorded by Momoe Yamaguchi in 1978, featuring renewed lyrics written by Shinji Tanimura who composed the original version. Onitsuka's interpretation was featured as the theme for Japan Railway's "Discover the West" campaign. At first, Onitsuka herself planned to show up in the campaign, but she refused later.

Around summer of that year, Onitsuka had suffered from vocal cord nodules. She underwent a surgery to get over poor throat condition, shortly after the recording of "Ii Hi Tabidachi, Nishi e." At the same time, she also managed to record part of a new song called "Watashi to Waltz wo". Like "Gekkou" and "Ryuseigun," it was featured as a closing theme for a sequel of Trick series aired in autumn 2003. The song was newly recorded after throat surgery, and issued as her final single from EMI in November 2003.

Fourth studio album was planned to be coming out in February 2004, and its catalogue number was already determined. But eventually it was not released, and a box set comprising all her previous singles was issued alternatively, without permission of her. The album reached #2 on the Oricon Daily Charts and #6 on the Weekly Charts.

Discography

Studio albums

{|class="wikitable" !rowspan="2"|Year !rowspan="2" width="100"|Album !colspan="1"|Chart positions !rowspan="2"|Label !rowspan="2"|RIAJ Certification |- !style="width:2em;font-size:80%"| JP
|- |rowspan="3"|2000 |"" |align="center"|- |rowspan="10"|EMI
Virgin Tokyo | |- |"" |align="center"|11 |align="center"|2x Platinum |- |"Cage" |align="center"|15 |align="center"|Gold |- |rowspan="2"|2001 |"" |align="center"|6 |align="center"|Platinum |- |"Infection"/"Little Beat Rifle" |align="center"|5 |align="center"|Gold |- |2002 |"" |align="center"|7 |align="center"|Gold |- |rowspan="4"|2003 |"Sign" |align="center"|4 | |- |"Beautiful Fighter" |align="center"|9 | |- |"" |align="center"|4 |align="center"|Gold |- |"" |align="center"|8 | |- |2004 |"" |align="center"|10 |rowspan="7"|Universal
A&M; | |- |rowspan="2"|2007 |"Everyhome" |align="center"|9 | |- |"" |align="center"|13 | |- |2008 |"" |align="center"|11 | |- |rowspan="3"|2009 | |align="center"|11 | |- |"" |align="center"|13 | |- |"" |align="center"|13 | |- |}

DVD

Me And My Devil (11 April 2001)

Cradle On My Noise L*I*V*E ~Live Insomnia Video Edition~ (7 November 2001)

Princess Believer (11 December 2002)

Ultimate Crash '02 Live At Budokan (21 May 2003)

the complete clips (1 December 2004)

NINE DIRTS AND SNOW WHITE FLICKERS (6 August 2008)

Trivia

*The production of LAS VEGAS started in 2006. Many of the songs were written during the year before last.

"Angelina" from her Las Vegas album, was named after Angelina Jolie.

During the long disappearance, Chihiro stayed at home most of the time, reading comics and listening to Tori Amos and Arashi.

Chihiro wishes to do live concerts. She is asking her record label to let her make a Europe tour.

She had a hard time recording the songs on 'Las Vegas' because she had lost weight. She once weighed only 36 kg.

She regards "Everyhome" as one of her most important works that can stand the test of time.

She prefers singing to writing songs. Prone to stage fright, she does not like live performance very much.

External links

Official website

Frozen Call The latest news on Chihiro Onitsuka in English

Nippop Profile | Chihiro Onitsuka

Chihiro Onitsuka International

References

Category:Japanese musicians Category:Japanese singer-songwriters Category:1980 births Category:Living people