Infections

Question 1

Influenza

Answer 1

an acute self-limited viral respiratory disease which is distributed worldwide and often occurs in widespread epidemics. It is characterized by fever, headache, myalgia, and prostration with bronchitis and bacterial pneumonia as common complications. Two distinct viruses cause the disease: influenza virus A and B which periodically undergo changes in antigenic composition making world population become newly susceptible to disease.

Question 2

Measles (Rubeola)

Answer 2

a highly contagious disease caused by RNA virus occurring chiefly in young children. An incubation period of 10-21 days precedes the prodrome with fever, cough, conjunctivitis, and malaise. Blue-gray spots with red areola, appear on the buccal membranes, and an erithematosus maculopapular rash is spreading downward from the head and face to the trunk and limbs lasting about five days. Recovery confers immunity, and live vaccine is available.

Question 3

Rubella

Answer 3

a mildly contagious viral (RNA) disease that usually affects children 5-15 years of age. The illness is mild and is characterized by lymphadenopathy, a maculopapular rash of 3-5 day’s duration, and conjunctivitis. Infection confers lifelong immunity. Congenital *** , when the fetus is infected during first trimester of gestation can be disastrous disease, causing fetal death, premature delivery, and number of severe congenital defects. A vaccine is available.

Question 4

Mumps

Answer 4

an acute generalized infection with a RNA virus which occurs most frequently in school-age children and is characterized by fever, malaise, and parotitis (salivatory glands are swollen and interstitium is infiltrated with lymphocytes). Complications include meningitis, pancreatitis, and in postpubertal patients orchitis (testis inflammation). The disease often occurs epidemically, especially in closed communities. Live vaccine is available.

Question 5

Rotavirus infection

Answer 5

is an RNA virus that spreads from person to person by oral-fecal route and usually infect young children, producing vomiting, fever, abdominal pain and profuse watery diarrhea (5 to 8 days) that can lead to dehydration and death if untreated.

Question 6

Varicella (chicken pox)

Answer 6

a contagious (respiratory route) viral disease caused by the varicella-zoster virus (herpesvirus), and characterized by lesions beginning as macules, developing into vesicles, after which the virus become latent (its reactivation in ganglion cells and infection of sensory nerve causes herpes zoster -‘shingles’). The incubation period is 17-21 days followed by fever, malaise and rash. The disease is relatively benign in children but may be serious in adults.

Question 7

Herpes simplex

Answer 7

a disease caused by infection with herpes simplex virus types 1 and 2, usually characterized by painful ulcerating vesicles 3-6 mm in diameter developing around the lips (usually type 1) or in the genital area (usually type 2). Infections may also involve the eye, the brain, or the meninges. The principal mode of spread is direct contact, and once acquired infection may be recurrent (physical illness or emotional stress).

Question 8

Infectious Mononucleosis

Answer 8

an acute infectious disease caused by the Epstein-Barr virus that most often affecting adolescents and young adults. It is usually characterized by fever, sore throat, malaise, fatigue, weakness, lymphodenopathy, hepatosplenomegaly and mononuclear leukocytosis (lymphocytes, monocytes and its immature forms).

Question 9

Staphylococcus aureus

Answer 9

the most common cause of suppuration and abscess formation involving: skin (pimples, boils, carbuncles), joints (arthritis), and bones (osteomyelitis), and it is leading cause of ineffective endocarditis.

Question 10

Streptococcus pyogens

Answer 10

is one of the most frequent bacterial pathogens of humans. It causes many diseases ranging from harmless infections of pharynx (‘strep throat’) and skin (impetigo), to serious infections like rheumatic fever.

Question 11

Streptococcus pneumoniae

Answer 11

is normal nasopharynx inhabitant and bacterial pathogen causing pneumonia, otitis media and meningitis that are preceded by common viral infections.

Question 12

Corynebacterium diphtheriae

Answer 12

an acute membranous (white-gray collection of necrotic tissue, fibrin and bacteria) infection of upper respiratory tract that may produce asphyxia. The gravity of infection is related to the production of a diffusing exotoxin that may cause myocarditis.

Question 13

Clostridium perfringens

Answer 13

is anaerobe spore forming bacilli causing common bacterial food poisoning ( no proper food refrigeration) and benign diarrheal disease or some time serious necrotizing enteritis. When this contaminate wounds after incubation period of 2-4 days after injury it may cause gas gangrene (fatal, gas-forming necrotizing infection).

Question 14

Clostridium tetani

Answer 14

is a cause of a severe infectious disease called *** which may develop when the bacillus gains access from the soil to the wound that provide anaerobic conditions for bacterial growth. It produces exotoxin that passes along the nerves from the wound to the spinal cord (1-3 weeks) where it stimulates motor neurons causing tonic muscle spasm -‘lockjaw’, opisthotonus, triasmus, glottal spasm and convulsions that may cause death. An effective vaccine is available

Question 15

Bordetella pertussis

Answer 15

cause pertussis (wooping cough), an acute, contagious disease commonly seen in children under 5 years of age. After an incubation of 7-14 days, the disease begins as a infection that progresses and it is characterized by paroxysms of coughing (lasts 4-5 weeks) which end in wooping inspiration. A vaccine is available an it is given in infancy.

Question 16

Haemophilus influenze

Answer 16

is small Gram-negative coccobacil that was once considered, mistakenly, the cause of pandemic influenza.
H. influenze is normally found in the human nasopharinx and it is the commonest cause of meningitis in children. It also causes sinusitis, otitis media, pneumonia, arthritis, epiglottitis ..

Question 17

Neisseria meningitidis

Answer 17

meningococcus is a Gram negative bacteria that causes pyogenic meningitis in children younger than 5 years of age. It is spread from one person to another primarily by respiratory droplets and as an epidemic disease occurs in crowded quarters. There are several different types: type A is a main cause of epidemic and B and C cause sporadic cases. Main characteristics are fever, headache and stiff neck and treatment require high doses of antibiotics.

Question 18

Neisseria gonorrhoeae

Answer 18

usually an infection of the is main cause of genitourinary organs. The disease is detectable three to five days after sexual contact with an infected partner, and it is usually characterized by a purulent urethral discharge in man. Symptoms are less prominent in women. If the antibiotic (penicillin) treatment is not started promptly, urethral stricture in man and fallopian tubes infection - salpingitis in women is a common complication.

Question 19

Escherichia coli

Answer 19

beside Salmonella typhi (typhoid fever caused by contaminated water and food- dairy products and shellfish) and Salmonella dysenteriae (causes dysentery - necrotizing infection of distal small intestine and colon), this is the most frequent cause of enteropathogenic bacterial infections. this bacteria is normally present in human colon, but aggressive when present in urinary tract, or meninges. Some strains release the endotoxins and cause serious intestinal disease.

Question 20

Treponema pallidum

Answer 20

is penicillin sensitive spirochete that cause sexually transmitted syphilis:

1. primary syphilis: chancre lesion at the site of bacterial inoculation and inguinal lymphoadenopathy
2. secondary syphilis: systemic bacterial chronic inflammation with lesions in skin, meninges, liver …
3. tertiary syphilis: is an asymptomatic period complicated with tissue necrosis (gumma lesions): result of obstructive vascular lesions of small arteries

Question 21

Chlamidia trachomatis

Answer 21

obligatory intracellular parasites, is the leading infectious cause of female sterility (scarring and narrowing of the fallopian tubes), and blindness by trachoma (chronic inflammation of the conjuctiva that eventually scars the cornea and make it opaque).

Question 22

Rickettsia

Answer 22

group of small pathogens mostly transmited between mammals by arthropodes (insects). They are obligated intracellular parasites that cause epidemic typhus, spotted fever etc. By injuring the endothelial cells, *** cause a hemorrhagic vasculitis that is often visible as a skin rash, but they may also cause pneumonia, hepatitis or injure CNS and cause death.

Question 23

Mycoplasmas

Answer 23

are the tiniest free-living organisms known. They spread from person to person in aerosols, bind to the surface of epithelial cells in the airways, and cause an atypical pneumonia (“walking pneumonia”) characterized by peribronchiolar infiltrates of lymphocytes and plasma cells. Infection is treated with antibiotics.