Chapter 40 Infectious Disorders

Stages of infectious disease Incubation period –Time between the invasion of an organism & the onset of S/S –7-10 days (maybe longer depending upon pathogen) Prodromal period –Time between the beginning of nonspecific symptoms & specific symptoms –Hours to a few days Illness –Specific symptoms are evident Convalescent period –Time between when the S/S begin to fade and a return to full wellness

Chain of infection Reservoir –Place in which organisms grow & reproduce Portal of exit –Method by which organisms leave an infected person’s body to be spread to another individual –Table 43-1 (blood, respiratory secretions, feces, & exudate from lesions) Means of transmission –Direct contact, indirect contact, fomites (inanimate objects, ex. food, bedding, towels, combs, drinking glasses, etc), insects, or vermin Portal of entry –Means by which a pathogen can enter an individual’s body –Inhalation, ingestions, breaks in the skin (ex. bites, abrasions, burns) Susceptible host

VIRAL INFECTIONS Viral exanthems (rashes) –Exanthem subitum (Roseola Infantum) Rash following a high fever –Rubella (German measles) Rarely seen because of MMR Important because it can cause serious birth defects –Measles (Rubeola) Rarely seen because of MMR Occurs with Coryza (rhinitis and sore throat), cough, and conjunctiva Koplik’s spots-whitish spots on the buccal membranes

Viral exanthems (rashes) –Chickenpox (Varicella zoster) Will become rare because of mandatory immunization Fluid filled vesicles that crust over, occur in different stages Highly contagious, spread by respiratory droplets as well as contact –Herpes zoster Same virus as chicken pox but usually occurs in older children/adults Causes painful vesicles along a dermatome May be treated with acyclovir –Erythema infectiosum (Fifth disease) “slapped cheeks” appearance and a lacy rash Important because it can cause birth defects –Smallpox (Variola) Important because of bioterrorism People with this are really sick with fever, chills, vomiting, then rash Rash progresses from macule to papule to vesicle to pustule.

VIRAL INFECTIONS Enteroviruses –Coxsackievirus infections Herpangina –Poliovirus infections: Poliomyelitis Occurs in other parts of the world IPV used now instead of OPV because of immunocompromised people contracting disease shed in stool

Cytomegalovirus Common cause of congenital infection in infants Some children are asymptomatic for years and then manifest with –Mental retardation/learning disabilities –Hearing loss/blindness Symptoms evident at birth can include –Jaundice –Seizures –Respiratory distress –microcephaly Therapy is experimental

Viruses causing central nervous system diseases –Rabies Other viral infections –Mumps Rarely seen because of MMR Mumps in a teenage or adult man can lead to sterility –Infectious mononucleosis S/S similar to tonsillitis with sore throat, lymphadenopathy, and fever Spleen is enlarged and fatigue can last ~6 weeks Treat symptoms only

OTHER INFECTIONS Scarlet fever –Group A beta-hemolytic strept –Often seen with Strept throat –Usually not seen with “cold” symptoms –Treated for days with antibiotics Eye infections/inflammations –Conjunctivitis (viral or bacterial) Starts in one eye and moves to the other Bacterial…purulent discharge Viral…watery discharge Schools or day care will only believe it is bacterial so treat with antibiotic ointment Highly contagious, can be spread by gnats

OTHER BACTERIAL INFECTIONS Anthrax –Important because of bioterrorism –Three types, inhalation, cutaneous, & gastro –Inhalation Most serious, >90% mortality Begins with flu like symptoms –Cutaneous Begins as a papule and progresses to a painless depressed black eschar Mortality 1% with antibiotic therapy –Gastrointestinal Acquired by eating undercooked meat infected with anthrax Develops abd. pain, diarrhea; mortality is 25% –Management Cipro for >18 years, Doxycycline for <18.

Diphtheria –S/S Foul nasal discharge, low-grade fever Gray membranes on tonsils and pharynx Neck edema –Therapeutic management DTaP…rarely seen due to immunization Pertussis –S/S See Box 40-1 pg –Therapeutic management DTaP…rarely seen due to immunization

OTHER BACTERIAL INFECTIONS Lyme disease –Transmitted by the deer tick –S/S Papule at the site of the tick progressing to a large swollen ring Systemic involvement –Therapeutic Management Amoxicillin or PCN V or doxycycline Prevention is the most important tool

OTHER INFECTIOUS PATHOGENS Rickettsial diseases –Rocky mountain spotted fever Transmitted by the wood, dog, or rabbit tick S/S –A reddened area develops at the site of the tick bite –Afterwards, rash, headache, fever, and mental confusion –CNS involvement Management –Tetracycline for 7-10 days –Prevention

OTHER INFECTIOUS PATHOGENS Helminthic infections –Roundworms (Ascariasis) –Hookworms –Pinworms