Impetigo - A Brief Discussion.

Introduction: This is the most superficial of the bacterial skin infections. It is one of the most common skin infections in children. but can also occur in adults.

Etiology: It is caused by Streptococcus pyogenes or Staph. aureus infecting the epidermal layer of the skin.

Clinical features: Because it is so superficial, there is weeping, crusting, and oozing of the skin.
Symptoms start with red or pimple-like sores surrounded by red skin. These sores can be anywhere, but usually occur on the face, arms and legs. The sores fill with pus, then break open after a few days and form a thick crust. They are often itchy, but scratching them can spread the sores.

Impetigo is contagious and can be spread to others through close contact or by sharing towels, sheets, clothing, toys, or other items.

Diagnosis: A specific microbiologic diagnosis is rarely made or necessary. It is mostly diagnosed by the clinical appearance of  “weeping, oozing, honey-colored lesions.”

Introduction to Septic Arthritis

A medical emergency, septic (infectious) arthritis is caused by bacterial invasion of a joint, resulting in inflammation of the synovial lining. If the organisms enter the joint cavity, effusion and pyogenesis follow, with eventual destruction of bone and cartilage.
Septic arthritis can lead to ankylosis and even fatal septicemia. However, prompt antibiotic therapy and joint aspiration or drainage cures most patients.

Pathophysiology
In most cases of septic arthritis, bacteria spread from a primary site of infection, usually in adjacent bone or soft tissue, through the bloodstream to the joint.
Common infecting organisms include four strains of gram-positive cocci—Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumoniae, and Streptococcus viridans—and two strains of gram-negative cocci—Neisseria gonorrhoeae and Haemophilus influenzae. Various gram-negative bacilli—Escherichia coli, Salmonella, and Pseudomonas, for example—also cause infection.
Anaerobic organisms such as gram-positive cocci usually infect adults and children older than age 2. H. influenzae most often infects children younger than age 2.

Risk factors
Various factors can predispose a person to septic arthritis. Any concurrent bacterial infection (of the genitourinary or the upper respiratory tract, for example) or serious chronic illness (such as cancer, renal failure, rheumatoid arthritis, systemic lupus erythematosus, diabetes, or cirrhosis) heightens susceptibility. Consequently, alcoholics and elderly people run a higher risk of developing septic arthritis.
Of course, susceptibility increases with diseases that depress the autoimmune system or with prior immunosuppressant therapy. I.V. drug abuse (by heroin addicts, for example) can also cause septic arthritis.
Other predisposing factors include recent articular trauma, joint surgery, intra-articular injections, and local joint abnormalities.

Introduction to Tetanus

Introduction: Tetanus, also known as lockjaw, is an acute exotoxin-mediated infection caused by the anaerobic, spore-forming, gram-positive bacillus Clostridium tetani. Usually, such infection is systemic; less often, localized.
Tetanus is fatal in up to 60% of non immunized persons, usually within 10 days of onset. When symptoms develop within 3 days after exposure, the prognosis is poor.

Etiology: Normally, transmission is through a puncture wound that is contaminated by soil, dust, or animal excreta containing C. tetani, or by way of burns and minor wounds. After C. tetani enters the body, it causes local infection and tissue necrosis. It also produces toxins that then enter the bloodstream and lymphatics and eventually spread to central nervous system tissue.
Tetanus occurs worldwide, but it’s more prevalent in agricultural regions and developing countries that lack mass immunization programs. It’s one of the most common causes of neonatal deaths in developing countries, where neonates of unimmunized mothers are delivered under unsterile conditions. In such neonates, the unhealed umbilical cord is the portal of entry.
In America, about 75% of all cases occur between April and September.

Clinical Features: 
The incubation period varies from 3 to 4 weeks in mild tetanus to less than 2 days in severe tetanus. When symptoms occur within 3 days after injury, death is more likely. If tetanus remains localized, signs of onset are spasm and increased muscle tone near the wound.
If tetanus is generalized (systemic), indications include 

• marked muscle hypertonicity, 
• hyperactive deep tendon reflexes, 
• tachycardia, 
• profuse sweating, 
• low-grade fever, and 
• painful, involuntary muscle contractions: 
• neck and facial muscles, especially cheek muscles—locked jaw (trismus) and a grotesque, grinning expression called risus sardonicus 
• somatic muscles—arched-back rigidity (opisthotonos), boardlike abdominal rigidity 
• intermittent tonic convulsions lasting several minutes, which may result in cyanosis and sudden death by asphyxiation.

Brief Summary of Ascariasis

Also known as roundworm infection, ascariasis is caused by the parasitic worm Ascaris lumbricoides. It occurs worldwide but is most common in tropical areas with poor sanitation and in Asia, where farmers use human stool as fertilizer. In the United States, it’s more prevalent in the South, particularly among younger children.

Causes
A. lumbricoides is a large roundworm resembling an earthworm. It’s transmitted to humans by ingestion of soil contaminated with human stool that harbors A. lumbricoides ova. Such ingestion may occur directly (by eating contaminated soil) or indirectly (by eating poorly washed raw vegetables grown in contaminated soil).
Ascariasis never passes directly from person to person. After ingestion, A. lumbricoides ova hatch and release larvae, which penetrate the intestinal wall and reach the lungs through the bloodstream. After about 10 days in pulmonary capillaries and alveoli, the larvae migrate to the bronchioles, bronchi, trachea, and epiglottis. There they’re swallowed and return to the intestine to mature into worms.

Signs and symptoms
Mild intestinal ascariasis may cause only vague stomach discomfort. The first clue may be vomiting a worm or passing a worm in the stool. In established infection, adult worms usually cause no symptoms. Severe disease, however, causes stomach pain, vomiting, restlessness, disturbed sleep and, in extreme cases, intestinal obstruction. Larvae migrating by the lymphatic and the circulatory systems cause various symptoms—for example, when they invade the lungs, pneumonitis may result.

Introduction to Scabies

An age-old skin infection, scabies results from infestation with Sarcoptes scabiei var. hominis (itch mite), which provokes a sensitivity reaction. It occurs worldwide, is predisposed by overcrowding and poor hygiene, and can be endemic.

Causes
Mites can live their entire life cycles in the skin of humans, causing chronic infection. The female mite burrows into the skin to lay her eggs, from which larvae emerge to copulate and then reburrow under the skin.
Transmission of scabies occurs through skin or sexual contact. The adult mite can survive without a human host for only 2 to 3 days.

Signs and symptoms
Typically, scabies causes itching that intensifies at night. Characteristic lesions take many forms but are usually excoriated and may appear as erythematous nodules.
Burrows are threadlike lesions about ¾? (2 cm) long and generally occur between fingers, on flexor surfaces of the wrists, on elbows, in axillary folds, at the waistline, on nipples in females, and on genitalia in males. In infants, the burrows may appear on the head and neck.
Intense scratching can lead to severe excoriation and secondary bacterial infection. Itching may become generalized secondary to sensitization.

Diagnosis
Superficial scraping and examination, under a low-power microscope, of material that has been expressed from a burrow may reveal the mite, ova, or mite feces. However, excoriation or inflammation of the burrow can make such identification difficult.
If diagnostic tests offer no positive identification of the mite and if scabies is still suspected (for example, close contacts of the patient also report itching), skin clearing that occurs after a therapeutic trial of a pediculicide confirms the diagnosis.

Introduction To Influenza

Also called commonly as the flu, influenza is an acute, highly contagious infection of the respiratory tract that results from three types of Myxovirus influenzae. It occurs sporadically or in epidemics (usually during the colder months). Epidemics tend to peak within 2 to 3 weeks after initial cases and subside within 1 month.
Although influenza affects all age-groups, its incidence is highest in schoolchildren. Its severity is greatest in the very young, the elderly, and those with chronic disease. In these groups, influenza may even lead to death.

Causes
Transmission of influenza occurs through inhalation of a respiratory droplet from an infected person or by indirect contact such as using a contaminated drinking glass. The virus then invades the epithelium of the respiratory tract, causing inflammation and desquamation.
One remarkable feature of the influenza virus is its capacity for antigenic variation. Such variation leads to infection by strains of the virus to which little or no immunologic resistance is present in the population at risk. Antigenic variation is characterized as antigenic drift (minor changes that occur yearly or every few years) and antigenic shift (major changes that lead to pandemics).

Influenza viruses are classified into three groups:
Type A, the most prevalent, strikes every year, with new serotypes causing epidemics every 3 years.
Type B also strikes annually, but only causes epidemics every 4 to 6 years.
Type C is endemic and causes only sporadic cases.

Signs and symptoms
After an incubation period of 24 to 48 hours, signs and symptoms appear: the sudden onset of chills, a temperature of 101° to 104° F (38.3° to 40° C), headache, malaise, myalgia (particularly in the back and limbs), a nonproductive cough and, occasionally, laryngitis, hoarseness, conjunctivitis, rhinitis, and rhinorrhea.
These signs and symptoms usually subside in 3 to 5 days, but cough and weakness may persist. Fever is usually higher in children than in adults. Also, cervical adenopathy and croup are likely to be associated with influenza in children. In some patients (especially elderly ones), lack of energy and easy fatigability may persist for several weeks.

Brief Summary of Anthrax

Anthrax is an acute bacterial infection that most commonly occurs in grazing animals, such as cattle, sheep, goats, and horses. It can also affect people who come in contact with contaminated animals or their hides, bones, fur, hair, or wool. It’s also used as an agent for bioterrorism and biological warfare.
Anthrax occurs worldwide but is most common in developing countries. In humans, anthrax occurs in three forms, depending on the mode of transmission: cutaneous, inhalational, and GI.

Etiology
Anthrax is caused by the bacteria Bacillus anthracis, which exists in the soil as spores that can live for years. Transmission to humans usually occurs through exposure to or handling of infected animals or animal products. Anthrax spores can enter the body through abraded or broken skin (cutaneous anthrax), by inhalation (inhalational anthrax), or through ingestion of undercooked meat from an infected animal (GI anthrax). Anthrax isn’t known to spread from person-to-person.

Signs and symptoms
From the time of exposure, signs and symptoms of infection usually occur within 1 to 7 days but may take as long as 60 days to appear. The signs and symptoms of anthrax depend on the form acquired:

Cutaneous anthrax: This is the most common form of anthrax. Skin infection may begin as a small, elevated, itchy lesion that resembles an insect bite, develops into a vesicle in 1 to 2 days, and finally becomes a small, painless ulcer with a necrotic (black) center. Enlarged lymph glands in the surrounding area are common. Without treatment, the mortality rate from cutaneous anthrax is 20%; the mortality rate is less than 1% with treatment.

Inhalational anthrax: The patient may initially report flulike signs and symptoms, such as malaise, fever, headache, myalgia, and chills. Such milder signs and symptoms may progress to severe respiratory difficulties, such as dyspnea, stridor, chest pain, and cyanosis, followed by the onset of shock. Even with treatment, inhalational anthrax is usually fatal.

Legionnaires’ disease

Introduction

An acute bronchopneumonia, legionnaires’ disease is produced by a fastidious, gram-negative bacillus. This disease may occur epidemically or sporadically, usually in late summer or early fall. Its severity ranges from a mild illness, with or without pneumonitis, to multilobar pneumonia, with a mortality as high as 15%. A milder, self-limiting form (Pontiac fever) subsides within a few days, but leaves the patient fatigued for several weeks; this form mimics legionnaires’ disease, but produces few or no respiratory symptoms, no pneumonia, and no fatalities.

Causes

The cause of legionnaires’ disease, Legionella pneumophila, is an aerobic, gram-negative bacillus that’s probably transmitted by an airborne route. With past epidemics, it has spread through cooling towers or evaporation condensers in air-conditioning systems. However, Legionella bacilli also flourish in soil and excavation sites. The disease doesn’t spread from person to person.

Predisposing Factors:

Legionnaires’ disease is more common in men than in women and is most likely to affect:

• middle-aged to elderly people
• immunocompromised people (particularly those receiving a corticosteroid, for example, after a transplant) or those with lymphoma or other disorders ssociated with delayed hypersensitivity
• patients with a chronic underlying disease, such as diabetes, chronic renal failure, or chronic obstructive pulmonary disease
• alcoholics
• cigarette smokers (three to four times more likely to develop legionnaires’ disease than nonsmokers).

Signs and symptoms
Although signs and symptoms of legionnaires’ disease emerge in a predictable sequence, onset of the disease may be gradual or sudden.

After a 2- to 10-day incubation period, nonspecific, prodromal signs and symptoms appear, including diarrhea, anorexia, malaise, diffuse myalgia and generalized weakness, headache, recurrent chills, and an unremitting fever, which develops within 12 to 48 hours with a temperature as high as 105° F (40.6° C). A cough then develops that is initially nonproductive but eventually may produce grayish, nonpurulent and, occasionally, blood-streaked sputum.

Toxic shock syndrome

Introduction

An acute bacterial infection, toxic shock syndrome (TSS) is caused by toxin-producing, penicillin-resistant strains of Staphylococcus aureus, such as TSS toxin-1 and staphylococcal enterotoxins B and C. The disease primarily affects menstruating women younger than age 30 and is associated with continuous use of tampons during the menstrual period.
TSS incidence peaked in the mid-1980s and has since declined, probably because of the withdrawal of high-absorbency tampons from the market.

Causes
Although tampons are clearly implicated in TSS, their exact role is uncertain. Theoretically, tampons may contribute to development of TSS by:

• introducing S. aureus into the vagina during insertion
• absorbing toxin from the vagina
• traumatizing the vaginal mucosa during insertion, thus leading to infection
• providing a favorable environment for the growth of S. aureus.

When TSS isn’t related to menstruation, it seems to be linked to S. aureus infections, such as abscesses, osteomyelitis, and postsurgical infections.

Signs and symptoms
Typically, TSS produces intense myalgias, fever over 104° F (40° C), vomiting, diarrhea, headache, decreased level of consciousness, rigors, conjunctival hyperemia, and vaginal hyperemia and discharge. Severe hypotension occurs with hypovolemic shock. Within a few hours of onset, a deep red rash develops—especially on the palms and soles—and later desquamates.

Major complications include persistent neuropsychological abnormalities, mild renal failure, rash, and cyanotic arms and legs.

West Nile Encephalitis

West Nile encephalitis, part of a family of vectorborne diseases that also includes malaria, yellow fever, and Lyme disease, is an infectious disease that primarily causes encephalitis (inflammation) of the brain. It’s caused by the West Nile virus (WNV), a flavivirus commonly found in humans, birds, and other vertebrates in Africa, West Asia, and the Middle East. The first documented cases of WNV in the Western Hemisphere didn’t occur until late in August 1999, when numerous dead birds in the New York, New Jersey, and Connecticut region tested positive for WNV after genetic sequencing. Scientists traced the Western Hemisphere origin of the disease to the vicinity of New York’s Bronx Zoo and believe that mosquitoes feeding on diseased birds helped to spread the disease.
In temperate areas, West Nile encephalitis occurs mainly in the late summer or early fall. In southern climates with milder temperatures, West Nile encephalitis can occur year round.
All persons living in endemic areas carry a risk of contracting West Nile encephalitis, but persons older than age 50 or those with compromised immune systems have the greatest risk.
The mortality rate of West Nile encephalitis is measured by case-fatality rates, which range from 3% to 15% (higher in the elderly population).

Causes
WNV is transmitted to humans by the bite of an infected mosquito (primarily the Culex species). Mosquitoes become infected by feeding on infected birds.
Ticks infected with WNV have been found in Africa and Asia, but their role in transmission and maintenance of the virus is uncertain; they aren’t considered vectors for WNV in the United States.
The Centers for Disease Control and Prevention has reported that there’s no evidence that a person can contract the virus from handling live or dead infected birds. However, barehanded contact when handling dead animals, including dead birds, should be avoided; if a dead animal must be handled, gloves or other protective measures should be used to dispose of the carcass. A dead bird is a sign that there may be infected mosquitoes in the area; findings should be reported to the nearest Emergency Management Office.

Introduction to Osteomyelitis

Introduction

A pyogenic bone infection, osteomyelitis may be chronic or acute. It commonly results from a combination of local trauma—usually quite trivial but resulting in hematoma formation—and an acute infection originating elsewhere in the body. Although osteomyelitis may remain localized, it can spread through the bone to the marrow, cortex, and periosteum.

Acute osteomyelitis is typically a blood-borne disease that usually affects rapidly growing children. Chronic osteomyelitis, although rare, is characterized by multiple draining sinus tracts and metastatic lesions.

Incidence

The incidence of both chronic and acute osteomyelitis is declining, except in drug abusers. With prompt treatment, the prognosis for acute osteomyelitis is good; for chronic osteomyelitis, which is more prevalent in adults, the prognosis is still poor.

Causes
The most common pyogenic organism in osteomyelitis is Staphylococcus aureus; others include Streptococcus pyogenes, Pneumococcus, Pseudomonas aeruginosa, Escherichia coli, and Proteus vulgaris. Typically, these organisms find a culture site in a hematoma from recent trauma or in a weakened area, such as the site of local infection (for example, furunculosis), and spread directly to bone.
As the organisms grow and form pus within the bone, tension builds within the rigid medullary cavity, forcing pus through the haversian canals. This forms a subperiosteal abscess that deprives the bone of its blood supply and eventually may cause necrosis. In turn, necrosis stimulates the periosteum to create new bone (involucrum); the old bone (sequestrum) detaches and works its way out through an abscess or the sinuses. By the time sequestrum forms, osteomyelitis is chronic.

Introduction to Salmonellosis

Introduction:

A common infection in the United States, salmonellosis is caused by gram-negative bacilli of the genus Salmonella, a member of the Enterobacteriaceae family. It occurs as enterocolitis, bacteremia, localized infection, typhoid, or paratyphoid .Non typhoidal forms usually produce mild to moderate illness with low mortality.
Typhoid, the most severe form of salmonellosis, usually lasts from 1 to 4 weeks. Mortality is about 3% in persons who are treated and 10% in those untreated, usually as a result of intestinal perforation or hemorrhage, cerebral thrombosis, toxemia, pneumonia, or acute circulatory failure.
An attack of typhoid confers lifelong immunity, although the patient may become a carrier. Most typhoid patients are younger than age 30; most carriers are women older than age 50. Incidence of typhoid in the United States is increasing as more travelers return from endemic areas.
Enterocolitis and bacteremia are common (and more virulent) among infants, elderly people, and people already weakened by other infections; paratyphoid fever is rare in the United States.
Salmonellosis is 20 times more common in patients with acquired immunodeficiency syndrome. Features are increased incidence of bacteremia, inability to identify the infection source, and tendency of the infection to recur after therapy is stopped.

Causes
Of an estimated 1,700 serotypes of Salmonella, 10 cause the diseases most common in the United States; all 10 can survive for weeks in water, ice, sewage, or food. Nontyphoidal salmonellosis generally follows the ingestion of contaminated or inadequately processed foods, especially eggs, chicken, turkey, and duck. Proper cooking reduces the risk of contracting salmonellosis.
Owning a pet turtle, lizard, iguana, or snake increases the risk factor because reptiles are carriers of salmonella. Salmonellosis may occur in children younger than age 5 from fecal-oral spread.
Typhoid results most commonly from drinking water contaminated by excretions of a carrier.

Signs and symptoms
Signs and symptoms of salmonellosis vary depending on the patient but usually include fever, abdominal pain, and severe diarrhea with enterocolitis. Headache, increasing fever, and constipation are more common with typhoidal infection.

Read the table below for different clinical variants of salmonellosis.

A Brief Introduction To Sexually Transmitted Diseases

Introduction And Definitions: Sexually transmitted infections (STIs) are the infections that are passed from one person to another through unprotected sex or genital contact.

Sexually transmitted infections refers to the mode of transmission of infection and the the reproductive tract infection refers to the site where the infection occurs. All Reproductive tract infections cannot be sexually transmitted infections.

The causes of Sexually transmitted Diseases (STDs) are bacteria, parasites, yeast, and viruses. There are more than 20 types of STDs, some of which include:

• Gonorrhoea
• Chylamydia
• Syphilis
• Trichomoniasis
• Chancroid
• Genital herpes
• Genital warts caused by HPV

Incidence: The incidence of STD's is increasing by 10% every year where safe sex practices are being ignored. 448 million new cases of curable STD's occur annually through out the world in persons aged 15 to 49 years.

Risk Factors

• Age less than 25 years
• Young age at first sex
• Non barrier contraception method
• New, multiple or symptomatic sexual partners

Women At More Risk: Most STDs affect both men and women, but in many cases the health problems they cause can be more severe for women. If a pregnant woman has an STD, it can cause serious health problems for the baby.

Women are physiologically more vulnerable than men. If they are asymptomatic they might not seek proper medical care and later it may lead to serious complications. Use of traditional vaginal medications and douching may also increase the risk for acquiring the STD's in women. With the exception of HIV all STD's have more threatening consequences in women than in men. In women it usually leads to infertility, ectopic pregnancy and cervical cancer.

Discussion on Some Common STDS: 

1. Chlamydia: is one of the most common STI and is easily passed on during sex. Most people don't experience any symptoms, so they are unaware they're infected.