INFECTIOUS DISEASES

PRINCE MED

Infections can have an infinite range of presentations

• Life threatening conditions (e.g. meningococcemia, COVID-19)

• Chronic diseases (e.g. H.pylori associated ulcers)

• No symptoms at all (e.g. TB infection)

APPROACH TO PATIENT WITH SUSPECTED INFECTION

History

• Core of diagnosing infectious disease

• Investigating the events surrounding the complaint & gathering subjective

data

Physical Examination

• Assessment of clinical findings

• Gathering objective data

INFECTIOUS DISEASE HISTORY

• Focuses on two aspects:

Exposure history

• Exposure to infected humans

• Exposure to animals, contaminated water/materials

Specific factors for susceptibility to infection

• Social History

• Dietary habits

• Travel history

PHYSICAL EXAMINATION

Particularly relevant:

• Vital signs

• Lymphatics

• Skin

• Foreign bodies

a hallmark of infection.

Fever

Fever of Unknown Origin

Temp >=38.3 DEGREE CELCIUS

For every 1 DEGREE C increase in core temperature, the heart rate typically

rises

15-20 beats/min

Normal heart rate:

Normal heart rate: 60-100 BPM

Having a lower heart rate than

expected for a given body

temperature.

RELATIVE BRADYCARDIA

(FAGET’S SIGN)

swollen lymph nodes

lymphadenitis

Physical examination must include evaluation of lymph nodes in

multiple regions of the body

• Location

• Size (normal < 1cm)

• Tenderness (painful to touch)

• Consistency (soft, firm, shotty, matted)

COMMON LOCATIONS

OF LYMPH NODES

• Cervical nodes

• Occipital nodes

• Infraclavicular nodes

• Axilalry nodes

• Inguinal nodes

• Epitrochlear nodes

Palpable epitrochlear nodes are

always pathologic

Examination of lymph nodes involves

inspection & palpation

SKIN EXAMINATION

• Signs of inflammation (redness, warmth, swelling)

• Rashes

• Skin Ulcers (pressure ulcers)

• Other lesions

Breach of barrier by foreign indwelling instruments can increase risk

for infection

FOREIGN BODIES

Placement of the ff instruments can be “points of entry” for

pathologic organisms:

• IV lines

• Foley catheter

• Surgical drain tubes

• Endotracheal tubes

Tests that either support or confirm the diagnosis of infectious disease.

DIAGNOSTIC EXAMINATIONS

High WBC count often associated with infections

Leukocytosis

Many viral infections present with

leukopenia

Important to assess the WBC differential

• Neutrophilia

• Lymphocytosis

• Eosinophilia

• Neutrophilia → bacterial

• Lymphocytosis → viral

• Eosinophilia → parasitic

Used to assess the general level of inflammation, usually followed serially

over time to monitor disease progression

INFLAMMATORY MARKERS

INFLAMMATORY MARKERS

Erythrocyte Sedimentation Rate (ESR)

C-Reactive Protein (CRP)

Procalcitonin

• Indirect marker of inflammation; changes slowly (weeks)

• Extremely elevated ESR > 100 is predictive of serious disease

Erythrocyte Sedimentation Rate (ESR)

Direct marker of inflammation; changes rapidly (daily)

C-Reactive Protein (CRP)

Used to identify if bacterial or viral

Procalcitonin

Critical for patients with suspected meningitis or encephalitis.

CEREBROSPINAL FLUID (CSF) ANALYSIS

CEREBROSPINAL FLUID (CSF) ANALYSIS

Characteristics observed:

• Opening pressure

• Cell counts

• Quality

• Gram stain & culture

Initial smear of the specimen that can be done immediately

GRAM STAIN

Mainstay of diagnosis of infectious diseases

CULTURE STUDIES

CULTURE STUDIES Ideally collected ______ Antibiotics

prior to starting

Can be used for further evaluation of lymphadenopathy in regions not

accessible externally

RADIOLOGY

Imaging that provides adjunct to physical examination findings

RADIOLOGY

Appears as abnormal densities on the lungs

LUNG INFECTION ON X-RAY

Appears as extra nodules especially in the mediastinum and mesentery

LYMPHADENOPATHY on ct scan

Top 10 communicable diseases in the Philippines

• Tuberculosis

• Dengue fever

• Pneumonia

• Malaria

• Infectious diarrhea

• Bronchitis

• Influenza

• Acute febrile illness

• HIV

• Lower respiratory tract infection (LRTI)

Human retrovirus

Mechanism: Destruction of CD4+ Helper T cells (lymphocytes), which

serve in disease recognition

The individual becomes very prone to a wide range of opportunistic

infections, tumors, dementia & death

HUMAN IMMUNODEFICIENCY VIRUS

Types of HIV

HIV 1

HIV 2

Stage of HIV

Incubation period: 1-3 weeks before symptoms

Primary

Symptoms Of Primary HIV Infection

• May be ASYMPTOMATIC

• May present with flu-like illness

• Muscle or joint pains

• Headache

• Enlarged lymph nodes (Lymphadenopathy)

• Enlarged liver or spleen

• Meningitis

• Encephalitis rash (small pink flat rash or bumps)

Stage of HIV

• Usually asymptomatic, lasts for 6 years or longer

• Large amounts of Anti-HIV antibody produced and is

detectable in blood, semen & secretions

Stage 2

If symptoms occur, patient presents with generalized

lymphadenopathy or the _________.

AIDS-related complex

Symptoms of AIDS-related complex

• Fever

• Fatigue

• Diarrhea

• Weight loss

• Night sweats

• Immunologic abnormalities

• Dementia

• Spontaneous neoplasms (masses)

Stage of HIV

• Symptoms of the opportunistic infections or neoplasms begin to

appear.

• The severity and frequency of infections and neoplasms is directly

related to the decline in CD4+ T cells.

stage 3

HIV-Defining Infections (Opportunistic Infections)

• Candidiasis of the esophagus, trachea, lungs

• Cervical carcinoma

• Coccidiomycosis

• Cytomegalovirus

• Encephalopathy, HIV related

• Histoplasmosis

• Kaposi’s sarcoma

• Lymphoma

• Mycobacterium avium complex

• Pneumocystis jiroveci

• Salmonella

• Toxoplasmosis

• Tuberculosis

Four categories of infection for HIV:

• Typical progressors- Majority; develop AIDS within 10 years

• Rapid progressors- Develop AIDS within 2-3 years of infection

• Long term non-progressors- Maintain low HIV RNA levels & normal CD4+ T cells

• Highly-exposed persistent seronegatives- Do not produce antibodies

Transmission of HIV

Sexual

Inoculation of blood

Perinatal

Diagnostic tests used to detect HIV:

• ELISA

• HIV1/HIV2 differentiation immunoassay

• Latex agglutination

• RT-PCR

• Isolation & culture

Baseline Laboratory Exams for HIV

• HIV antibody testing

• CD4+ T-cell count

• CBC, Blood chemistry, etc

• Tests for other infections:

• Urinalysis

• Tuberculin skin test

• RPR or VDRL for Syphilis

• Hepatitis serologies

• Pap smear for women

Therapy & Prevention of HIV

• Highly Active Anti-retroviral therapy (HAART)

- Free at Infectious Control Hubs (e.g. WVMC, TMC)

- HAART should be started in ALL HIV-infected individuals

• Education of HIV risk behaviors & how to prevent transmission to

others

• Specific therapy for opportunistic infections

Monitoring Treatment for HIV

Two markers used to routinely assess HIV patients:

• CD4+ T cell count

- To assess immune function

• Plasma HIV RNA

-To detect HIV levels in the blood

monitoring treatment for HIV Should be measured/repeated _____.

every 3 to 6 months

The _____ the CD4 Count, the ____ complicated

the infections are

Lower, More

Febrile disease caused by the blood parasite

Plasmodium that is primarily transmitted by the bite of

an infected mosquito (Anopheles)

MALARIA

Incubation period of malaria

Incubation period: 7 to 30 days

Malaria is caused by the blood parasite ___.

Plasmodium

CYCLE OF SYMPTOMS for malaria

• Prodrome- Fever, headache, muscle pains

• Cold Stage - Shaking chills followed by high-grade fever (40-41C) that lasts about 24hours

• Wet Stage- Body temperature quickly back to normal, followed by profuse sweating

BASIC TYPES/PATTERNS of malaria

• Benign Tertian (P. vivax & P. ovale)- Fever every 2nd day (e.g. MON-Tue-WED-Thu)

• Benign Quartan (P. malariae)- Fever every 3rd day (e.g. MON-Tue-Wed-THU)

• Malignant Quartan (P. ffalciparum- Cold stage less pronounced, and no wet stage

- Fever stage is prolonged and intensified

- More dangerous due to complications of capillary blockage or bleeding

DISTRIBUTION OF MALARIA IN THE PHILIPPINES

Endemic in Palawan

DIAGNOSIS OF MALARIA

• Visualization of parasitized erythrocytes in thick or thin peripheral blood smears.

- Ring forms inside RBCs

- “headphones”

• Serology

- ELISA

- Immunofluoresence

PROPHYLAXIS OF MALARIA

Taken before, during, and after travel to an endemic place

• In Chloroquine-sensitive areas - Chemoprophylaxis: Chloroquine

• In Chloroquine-resistant areas - Chemoprophylasis: Quinine, Mefloquine, Atovaquone/Proguanil

TREATMENT OF MALARIA

Depends on local sensitivity pattern of malaria in the area

• In Chloroquine-sensitive areas - Treatment of choice: Chloroquine  Primaquine

• In Chloroquine-resistant areas - Treatment of choice: Quinine + Doxycycline