Operational Medicine 2001
Field Medical Service School
Student Handbook

DISEASES OF OPERATIONAL IMPORTANCE

FMST 0605

17 Dec 99

TERMINAL LEARNING OBJECTIVE

1.      Given a combat environment (day and night) and individual combat equipment, demonstrate knowledge of diseases of operational importance, per the references.  (FMST 06.05)

ENABLING LEARNING OBJECTIVES

1.  Without the aid of reference materials, determine the factors effecting  infectious diseases, per the student handbook.  (FMST 06.05a)

2.   Without the aid of reference materials and given a list of diseases, select the category of infectious diseases of military importance that may compromise a military mission, per the student handbook.  (FMST 06.05b)

3.      Without the aid of reference materials and given a list of diseases, select the mode of transmission for each disease, per the student handbook.  (FMST 06.05c)

4.      Without the aid of reference materials and given a list of diseases, select the personal protection measures for each disease, per the student handbook.  (FMST 06.05d)

5.      Without the aid of reference materials, determine the correct purpose of disease surveillance, per the student handbook.  (FMST 06.05e)

6.      Without the aid of reference materials, determine the correct purpose of vector surveillance, per the student handbook.  (FMST 06.05f)

7.      Without the aid of reference materials and given a list of diseases, select the symptoms for each disease, per the student handbook.  (FMST 06.05g)

8.      Without the aid of reference materials and given a list, identify the appropriate vector for selected diseases, per the student handbook.  (FMST 06.05h)

9.      Without the aid of reference materials and given a list, identify the appropriate preventive measures for selected vector borne diseases, per the student handbook.(FMST 06.05I)

OUTLINE

A.     Background – Throughout history, the United States Armed Forces have traveled to regions both for training and actual combat.  A disturbing fact is that Disease Non-battle Injuries (DNBI), such as malaria, Dengue Fever, and Yellow Fever historically have killed more Americans than combat wounds killed in action or died of wounds (KIA/DOW).

B.      Infectious Disease

1. Of all life forms, microorganisms compose the largest population inhabiting soil,

plants, animals, minerals, and humans. Infectious disease ranks fifth in causes of death in the United States.

2. Steps of Infection Process

a.       Contamination – the presence of an infectious agent on a body surface or object

b.      Infection – implantation and successful reproduction of an infectious agent n a living host 

c.       Subclinical infection – no clinical symptoms present 

d.      Infectious disease – tissue injury or physiologic reponse produces clinical symptoms

C.     Chain of Transmission

1. Reservoir – environment of the pathogen in which it depends on for reproduction and survival.  Examples include: 

                  a.  Person

            b.  Animal

                  c.  Arthropod

                  d.  Plant

                  e.  Water

                  f.   Food

                  g.  Soil

2. Portal of Exit – The pathogen may escape through more than one portal of exit

a.  Genitourinary tract - Gonorrhea

                  b.  Intestinal tract - Hepatitis

                  c.  Oral cavity - Tuberculosis

                  d.  Open lesion - Syphilis

3. Transmission –

a.  Direct: Physical contact between source and victim (sexually, orally, fecal

     contamination, airborne droplets)

            b.  Indirect transmission: Requires pathogen to survive on an inanimate vehicle

                 without the host (air, water, food, soil, fomite)

4. Portal of Entry -  The way an organism gets into its host

a.  Ingestion

                  b.  Inhalation

                  c.  Mucous membrane

                  d.  Placenta

5. Host Susceptibility  - May be influenced by:

                   a. Age

             b. Sex

                   c. Ethnic group

                   d. Cultural behaviors regarding eating and personal hygiene

                   e. Health status

                   f.  Presence of concurrent disease

D.     Breaking the Chain of Transmission

1. Destroy non-human reservoirs and vectors

2. Isolate infected persons

3. Using precautions with infected body fluids and contaminated objects

4. Improve host resistance

5. Eliminate or alter the virulence of the pathogen

E.      Types of Infectious Agents

1. Virus:

a.       Considered parasitic in nature

b.      Is dependent on host cell for metabolic and reproductive needs

c.       Consists of either DNA or RNA material

d.      Has a protein capsid (capsule) instead of a true cell wall

2. Rickettsia:

a.       A genius of microorganism that are between viruses and bacteria

b.      Considered parasitic in nature

c.       Is dependent on host cell for metabolic and reproductive needs

d.      Usually transmitted by arthropods

3. Bacterial:

a.       Unicellular microorganism that multiple by cell division,

b.      Has a cell wall

c.       Can be aerobic or anaerobic

d.      Can be motile or non-motile

e.       9 different forms (diplococci, bacilli, vibrios, etc).

4. Fungi:

a.       Plant-like organisms that include yeasts and molds

b.      May be single celled (yeast) or multicellular (molds).

c.       No chlorophyll, therefore is:

1)     saprophytic (eat dead tissue) 

2)     parasitic (live inside cells)

5. Helminth:

a.       A worm-like animal

b.      May be either free-living or parasitic

F.      Factors Effecting Infectious Disease

1. Poor Sanitation – Insufficient control over water sources, lack of proper waste

      disposal

2. Climatic Influences – heat, humidity, and rainfall

3. Malnutrition – Inadequate amount of food for proper nourishment

4. Over-crowding – Lack of sufficient space to assist in the prevention of infectious

            diseases transmitted from person to person

5. Incomplete Immunizations – insufficient antibody titers to adequately fight off

      infectious diseases

6. Incomplete Chemoprophylaxis – Medications intended to prevent diseases such as

      isoniazid (INH) therapy for tuberculosis and Primaquine or Mefloquine for

      Malaria   

G.     Categories of Infectious Diseases

1. Respiratory

a.       Influenza

1. Types

     a) A is associated with epidemics and pandemics

     b) B is associated with regional and widespread epidemics

     c) C is associated with sporadic cases and localized outbreaks

Note:  Types A and B are the viruses responsible for the frequent epidemics. These viruses undergo antigenic changes which necessitates the annual flu vaccine.

      2. Signs / Symptoms:

a)      Headache

b)      Fever

c)      Myalgia

d)      Cough

e)      Sore throat

      3. Mode of transmission:

a)      Person to person contact

b)      Airborne droplet  spray infects people

c)      Contaminates with viruses that can transmit infection.

 4.Prevention and control:

a)      Immunization – annual flu shot given before flu season

b)      Handwashing – assists in breaking the chain of infection from person to person

c)      Isolate patients – use respiratory precautions

d)      Avoid overcrowding – berth only the recommended numbers in tents

or other berthing spaces

e)      Educate population – explain modes of transmission and prevention to

your personnel

b.      Pneumococcal Pneumonia

1.      Infectious Agent – Streptococcus pneumoniae

2.      Signs / Symptoms – Acute bacterial infection

a)      Sudden onset with shaking chill

b)      Fever

c)      Pleural pain

d)      Productive cough of “rusty” sputum

3.      Mode of transmission:

a)      Direct - droplets spread by oral contact

b)      Indirect - through articles freshly soiled with respiratory discharge.

4.      Prevention and control:

a)      Immunization

b)      Avoid overcrowding

c)      Universal precautions

d)      Education

c.       Tuberculosis

1.      Infectious Agent – Mycobacterium tuberculosis, M. africanum, M. bovis

2.      Signs / Symptoms:

a)      Pulmonary- infection in the lungs

1) Often asymptomatic - just “not feeling well”

2) Fever

3) Night sweats

4) Weight loss

5) Productive cough

6) Hemoptysis

b)      Extrapulmonary - infection of the lymph nodes, bones, abdominal organs    

1) Lesions on that site

2) Swelling of lymph nodes

3) Collapsed vertebrate

3.      Mode of transmission:

a)      Inhalation of droplet nuclei  as in coughing, singing, sneezing

b)      Ingestion of unpasteurized milk or diary products

4.      Prevention and control:

a)  Annual tuberculin skin testing using purified protein derivative (PPD) b)  Avoid exposure in crowded environments such as prisons, homeless

     shelters

c)  Chemoprophylaxis for convertors using Isoniazid therapy

d)  Isolate active cases of TB

e)  Do not consume unpasteurized dairy products

d.      Anthrax

1.      Infectious Agent – Bacillus anthracis, a gram positive, encapsulated, spore

forming, non-motile rod.

2.      Signs / Symptoms:

a)      Inhalation

1)      Onset is gradual and nonspecific with fever, malaise, and fatigue

2)      Nonproductive cough and mild chest discomfort

3)      After 2-3 days there is an abrupt development of severe respiratory distress with dyspnea, diaphoresis, stridor (loud harsh breathing), and cyanosis

4) X-rays reveal widened mediastinum (space beneath the sternum

    containing the heart, aorta, and trachea) often with pleural effusions

5) Shock and death occurs within 24-36 hours of respiratory distress

b)      Cutaneous

1)      Itching of skin that was exposed, followed by a lesion that 

      becomes papular, then vesicular

2)      In 2-6 days the lesion develops into a depressed blackened eschar

(a hard crust over a raw surface)

3.      Mode of Transmission:

a)      Direct contact with tissues of affected carcasses or inhalation of spores

4.   Prevention and Control:

a)      Educate personnel on the handling of potentially contaminated

      carcasses or materials

b)      Immunization with purified B. anthracis protective antigen. Intervals are: initial, 2, 4, 6, 12, and 18 months.  This interval of vaccination has been shown to be effective in preventing or significantly reducing the incident of inhalation anthrax.

2. Arthropod-borne:

                 a.  Malaria

                      1.  Infectious agent: Plasmodium falciparum, P. vivax, P. malariae,  P. ovale

                      2.  Sign / Symptoms:

a)      Fever

b)      Headache

c)      Chills

d)      Sweats

e)      Cough

f)        Diarrhea

               3.  Mode of transmission:

a)      The bite of an infected female Anopheles mosquito

   4.  Prevention and Control:

a)      Education about individual personal protective  measures (PPM)                 

b)      Proper use of DEET on the skin

c)      Permethrin on uniforms and bednetting

d)      Control of breeding sites

e)      Chemical vector control

f)        Chemoprophylaxis/terminal prophylaxis such as mefloquine, doxycycline and primaquine

                 b.  Dengue Fever

1.      Infectious agent: Aedes aegypti, A. albopictus

2.      Signs / Symptoms

a)      Sudden onset of fever

b)      Intense headache

c)      Myalgia (tenderness or pain of the muscles)

d)      Retro orbital pain (pain in back of the eyes)

e)      Anorexia

f)        GI disturbances

g)      Rash

3.      Mode of Transmission:

a) The bite of an infected female mosquito

4.      Prevention and Control:

a) Education about individual personal protective  measures (PPM)                 

b) Proper use of DEET on the skin

c) Permethrin on uniforms and bednetting

                                  d) Control of breeding sites

                                  e) Chemical vector control

                                  f) Chemoprophylaxis/terminal prophylaxis such as mefloquine,

                                     doxycycline and primaquine

                 c.  Japanese Encephalitis

1.      Infectious agent: Culex tritaeniorhynchus, C. vishnui, C. geledus

2.      Signs / Symptoms:

a)      Most infections are asymptomatic

b)      Mild cases often occur as a febrile headache or aseptic meningitis.

c)      Symptomatic infections can be marked by acute onset of headache, high fever, stupor, disorientation, coma, tremors, occasional convulsions (especially infants) and spastic (rarely flaccid) paralysis

d)       About 25% of cases are fatal

3.      Mode of Transmission:

a)      Bite of an infected female mosquito

4.      Prevention and Control:

a) Education about individual personal protective  measures (PPM)                 

b) Proper use of DEET on the skin

c) Permethrin on uniforms and bednetting

                                  d) Control of breeding sites

                                  e) Chemical vector control

                                  f) Chemoprophylaxis/terminal prophylaxis such as mefloquine,

                                      doxycycline and primaquine