chapter 4 infectious disease hybrid 2009

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Infectious Diseases

Chapter 4



Infectious Diseases

When pathogenic microorganism find a

suitable environment for growth in the host.

MicroorganismsBacteria

Viruses

ParasitesFungi

Protoza



Parasitic Organisms

Round Worm Pin Worm

Hookworm

Tapeworm



Fungal Organisms

Epidermophyton floccosum

Candida albicans



Protozoa Organisms Giardia

Malaria

Trichomonas vaginalis



Viruses

HIV Virus

Influenza Virus



Bacteria Organisms

Bacillus anthracis

Staphlococcus or

Streptococcus



Transmission of Organisms

Direct Contact

Indirect Contact

Droplet Contact

Airborne Transmission

Fecal-oral Transmission Vector-borne Transmission



Emerging Infectious Diseases

Incidence of disease has increased within past 10 years Emerging Infectious Diseases

West Nile Virus Infection

SARS

Malaria Smallpox & Monkeypox

Anthrax

Hantavirus

Lyme Disease Escherichia coli O157:H7



West Nile Virus Encephalitis:

Etiology Virus that affects birds

Mosquito feeds on dead

birds

Virus enters mosquito’s

saliva

Mosquito bites human

Can cause Encephalitis



WNV: Diagnostic Tests

Blood tests looking for the virus(antigen)

and/or antibody in patients serum.

Antibody TestsAntibody Screen

ELISA Methodology

Antigen TestsPCR – polymerase chain reaction

Looks at DNA sequencing

NAT – nucleic acid testing



WNV: Treatment & Prevention

No known treatment Use analgesics & medications to relieve

symptoms

Alternative therapies

Prevention Use DEET mosquito repellant

Eliminate mosquito breeding sites

Install window & door screens



Malaria: Etiology Parasitic Infection

Transmitted via

mosquitoes

Parasites travel to liver & transform to

merozoites & ring forms

Merozoites enter RBCs



Malaria: Signs & Symptoms

Chills & fever

Headache & body aches

Nausea Vomiting

Diarrhea

Anemia

Jaundice



Malaria: Diagnostic Tests

Blood smear looking for the malariaparasites in red blood cells.

If found, must be reported to Health

Department for identification of species.



Malaria: Treatment

Antimalaria drugs; varies with species

Blood donationsTraveled to endemic area – defer for 1-3

years

If had malaria –defer 3 years after full

recovery.



Influenza

Acute infectious disease

Causitive Agent Infuenza A, B or C

Contracted by close person to person contact Respiratory droplets through coughing & sneezing

Touching infected objects & rubbing eyes, nose & mouth

Influenza virus infects the epithelial cells of therespiratory tract. Immunity Against

Interferon & the actions of cytotoxic T-cells.



Influenza: Signs & Symptoms

Most severe in children & elderly Fever Myalgia & Headache

Dry cough; nasal discharge Croup Complications

PneumoniaEncephalopathyGuillian-Barre SyndromeReyes Syndrome



Influenza

Diagnostic & Prevention Diagnosis

Viral Culture – 3-5 days

Polymerase Chain Reaction (PCR) – 2 hours Detects viral RNA

Rapid Screening Test – 15 minutes

Prevention

Influenza Vaccination (Flu Shot)



Smallpox (Variola virus)

Serious, contagious, and sometimes fatalinfectious disease

No specific treatment Prevention is vaccination Virus has been eradiated except for

laboratory stockpiles Fear of bioterrorism



Monkey pox 1st outbreak in 2003 from handling prairie

dogs Rash→papule→vesicle that crusts over Fever, headache, malaise, backache,

lymphadenopathy Culture the virus or viral DNA antigen

testing Give antipyretics & analgesics



Hantavirus Pulmonary Syndrome

1st case in 1993 in SW US

Rodents shed virus in urine, dropping and salvia

which become aerosolized when walking & kicking

up ground Transmitted by breathing in aerosolized droplets

Flu-like symptoms; respiratory distress

Treat the symptoms High rate of mortality due to respiratory failure.



Anthrax: Signs & Symptoms

Cutaneous anthrax raised itchy bump that develops into an ulcer

Inhalation anthrax fever, malaise, fatigue and sometimes a dry

cough; period of improvement followed by a crash -- trouble breathing,

sweating, bluish colored skin, shock death occurs 24-36 hours after the severe

symptoms begin

Gastrointestinal anthrax nausea, loss of appetite, vomiting, fever

followed by abdominal pain, vomiting of blood,and severe diarrhea.



Inhalation Anthrax-Why so lethal?

Spores lay dormant in

powder

Germinate in lung tissue Multiplies to cause

infection

Toxins from bacteria

cause hemorrhaging &

tissue death



Anthrax: Diagnostic testing

Culture of the blood,

skin lesions, or

respiratory secretions

Measuring specific

antibodies in the blood

Biopsy for PCR &

Immunochemistry



Anthrax: Treatment

Cutaneous & Gastrointestinal - antibiotics

(amoxycillin, ciprofloxacin, erythromycin

and gentamycin) to treat skin andgastrointestinal infections.

Respiratory anthrax – Broad spectrum

antibiotics very hard to treat and nearly always fatal.



Lyme Disease: Etiology

Tick-transmitted

spirochete – Borrelia

burgdorferi Very Small ticks

Seen more commonly

in northeast.



Lyme Disease: Signs & Symptoms

Stage I – erythema chronicum

migrans (ECM) - bulls eye rash

Stage II – affects CNS ( meningitis, nervedamage and facial palsy

Stage III – chronic arthritis & continuingneurological problems

Fever, fatigue, chills, stiff neck, joint & musclepain



Lyme Disease: Diagnosis

Mainly done bysymptoms, especiallyEMC

Confirmation – takesweeks for antibody toappear, but bloodtests (ELISA & IFA)

Western Blot-lookingfor the viral antigen

Western Blot

Test looking for

DNA of organism

Simple Screening Test

looking for antibody



Escherichia Coli O157:H7

O157:H7 – one of many strains of

Escherichia coli bacteria.

O157:H7 – produces a harmful toxin Organisms found in cattle feces;

transmitted to humans through

contaminated meat Food born illness



E. Coli Infection: Signs & Symptoms

Abdominal cramps

Bloody stoolsHemolytic uremic syndrome (acute

kidney failure) O157:H7



E. Coli Infection: Diagnosis Treatment

Diagnosis: stool

cultures - growing the

organisms on an agar plate.

Treatment: Antibiotics



Multidrug-Resistant Organisms

Organisms resistant to antibiotics

MROsMRSA – methicilin/oxacillin-resistant

Staphylococcus aureus

VRE – vancomycin-resistant enterococci

PRSP – penicillin-resistant Streptococcus pneumoniae

ESBL – extended-spectrum beta-lactamase



Preventing Emerging Infectious

Diseases - CDC One of CDC’s goals/strategies for 21st

century – surveillance of infections.

Educating physicians & parents whyantibiotics should not be given for most

colds, coughs, sore throats, & runny

noses.



Immunosuppressant Syndromes

Chronic Fatigue

Syndrome

Acquired

Immunodeficiencysyndrome (AIDS)/

HIV Infection



Chronic Fatigue Syndrome Chronic debilitating fatigue

No known cause – associated with viral

infections.

Symptoms Fever & chills

Arthralgia

Sore Throat Lymphadenopathy

Sleep disturbance

Neurological – irritability, confusion, depression



Acquired Immunodeficiency

Syndrome (AIDS) Severe illness associated with HIV

HIV is a retrovirus that destroys T4

(helper) lymphocytes

Transmitted via blood & other body

fluids

First case diagnosed in 1981



AIDS STATISTICS

SEX

AGE

Transmission



AIDS’ Signs & Symptoms Fever & flulike symptoms

Pulmonary Infections: Pneumocystis jiroveci

Shortness of breath, dyspnea, coughing, chest pain

Gastrointestinal symptoms: Loss of appetite, nausea, vomiting, oral and esophagel

candidiasis, chronic diarrhea

Neurological symptoms

Memory loss, headache, depression, confusion

Malignancies

Kaposi’s sarcoma,



AIDS’ Diagnosis

ELISA Antibody Test Tests detects antibody

produced to HIV

If positive, must be

confirmed using Western

Blot Test

Viral Load TestWestern Blot Test



AIDS’ Treatment Nucleoside Reverse Transcriptase Inhibitors – to

reduce the HIV in body Abacavir (Ziagen, ABC) Didanosine (Videx, dideoxyinosine, ddI)

Emtricitabine (Emtriva, FTC) Lamivudine (Epivir, 3TC) Stavudine (Zerit, d4T) Tenofovir (Viread, TDF) Zalcitabine (Hivid, ddC) Zidovudine (Retrovir, ZDV or AZT)

Alternative treatments to keep immune systemhealthy



Childhood Communicable Diseases

Rubeola (Measles) Rubella (German Measles)

Erythema Infectiosum (Fifth Disease) Mumps Varicella (Chickenpox) Diphtheria Pertussis (Whooping Cough) Tetanus (Lockjaw)



Immunization Protection against communicable diseases

chapter 4 infectious disease hybrid 2009

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