INFECTIOUS DISEASE

Emerging infectious diseases are infections that have newly appeared in a population or have existed but are rapidly increasing in incidence or geographic range.  In the mid-twentieth century, antibiotics cured many of the diseases that were life-threatening. Eradicating the specter of debilitating and fatal diseases, people were optimistic about a world without infectious diseases. Since then new diseases emerged that temper that optimism, such as AIDS and new strains of influenza. In recent years, the increasing mobility of people throughout the world brought the recurrence of diseases that were thought to be eradicated such as monkey pox.
(Minnesota State Hazard Mitigation Plan; Centers for Disease Control Monkeypox web site, <www.cdc.gov/ncidod/monkeypox/index.htm.)

History

Bacteria existed long before humans evolved, and bacterial diseases probably co-evolved with each species. Many bacterial diseases that we see today have been around for as long as we have, others may have developed later.

Between the middle of 1918 and the middle of 1919, the worldwide Spanish Influenza epidemic killed  at least 21 million human beings – well over twice the number of combat deaths in World War I.  The “Spanish” flu had first appeared in America in spring 1918.

All over the world, Spanish Influenza ravaged civilian populations.  One-quarter of all Americans suffered bouts of influenza.  More than 600,000 Americans died, 10,000 of them were Minnesotans.  The city of St. Paul saw more than 1,000 deaths; Minneapolis, more than 1,300.

In recent years, the State of Minnesota has not had an infectious disease outbreak that reached epidemic proportion.

 

Time Course of Common Infections                  (all in days)

Disease

Incubation period

Latency period

Infectious period

Measles

8-13

6-9

6-7

Mumps

12-26

12-18

4-8

Pertussis

6-10

21-23

7-10

Rubella

14-21

7-14

10-12

Diphtheria

2-5

14-21

2-5

Varicella

13-17

8-12

10-11

Hepatitis B

50-110

13-17

19-22

Poliomyelitis

7-12

1-3

14-20

Influenza

1-3

1-3

2-3

Source: http://uhavax.hartford.edu/bugl/histepi.htm

The tables on the next two pages list several common source and host-to-host epidemics, the causative agent (followed by V for virus, B for bacteria, and P for protozoa), sources of infection, and the reservoirs of the infection. Current knowledge tells us that humans are the only reservoirs for sexually transmitted diseases.

 

Common Source Epidemic Diseases

Disease

Causative Agent

Infection Sources

Reservoirs

Anthrax

Bacillus anthracis (B)

Milk or meat from infected animals

Cattle, swine, goats, sheep, horses

Bacillary Dysentery

Shigella dysenteriae (B)

Fecal contamination of food and water

Humans

Botulism

Clostridium botulinum (B)

Soil-contaminated food

Soil

Brucellosis

Brucella melitensis (B)

Milk or meat from infected animals

Cattle, swine, goats, sheep, horses

Cholera

Vibrio cholerae (B)

Fecal contamination of food and water

Humans

Giardiasis

Giardia spp. (P)

Fecal contamination of water

Wild mammals

Hepatitis

Hepatitis A,B,C,D,E (V)

Infected humans

Humans

Paratyphoid

Salmonella paratyphi (B)

Fecal contamination of food and water

Humans

Typhoid Fever

Salmonella typhi (B)

Fecal contamination of food and water

Humans

Host-to-host Epidemics

Disease

Causative Agent

Infection Sources

Reservoirs

Respiratory Diseases

Diphtheria

Corynebacterium diphtheriae (B)

Human cases and carriers; infected food and fomites

Humans

Hantavirus pulmonary syndrome

Hantavirus (V)

Inhalation of contaminated fecal material

Rodents

Meningococcal meningitis

Neisseria meningitidis (B)

Human cases and carriers

Humans

Pneumonococcal pneumonia

Streptococcus pneumonia (B)

Human carriers

Humans

Tuberculosis

Mycobacterium tuberculosis (B)

Sputum from human cases; contaminated milk

Humans, cattle

Whooping cough

Bordetella pertussis (B)

Human cases

Humans

German measles

Rubella virus (V)

Human cases

Humans

Influenza

Influenza virus (V)

Human cases

Humans, animals

Measles

Measles virus (V)

Human cases

Humans

Table 3-22 Continued

 

 

 

Disease

Causative Agent

Infection Sources

Reservoirs

Sexually Transmitted Diseases

HIV-Disease

HIV (V)

Infected body fluids, blood, semen, etc.

Humans

Chlamydia

Chlamydia trachomatis (B)

Urethral, vaginal, and anal secretions

Humans

Gonorrhea

Neisseria gonorrheae (B)

Urethral and vaginal secretions

Humans

Syphilis

Treponema pallidum (B)

Infected exudate or blood

Humans

Trichomoniasis

Trichomonas vaginalis (P)

Urethral, vaginal, prostate secretions

Humans

Vector-borne diseases

Epidemic typhus

Rickettsia prowazekii (B)

Bite by infected louse

Humans, lice

Lyme disease

Borrelia burgdorferi (B)

Bite from infected tick

Rodents, deer, ticks

Malaria

Plasmodium spp. (P)

Bite from infected Anopheles mosquito

Humans, mosquitoes

Plague

Yersinia pestis (B)

Bite by infected flea

Wild rodents

Rocky Mountain spotted Fever

Rickettsia rickettsii (B)

Bite by infected tick

Ticks, rabbits, mice

Direct-contact diseases

Psittacosis

Chlamydia psittaci (B)

Contact with birds or bird excrement

Wild and domestic birds

Rabies

Rabies virus (V)

Bite by carnivore

Wild and domestic carnivores

Tularemia

Franciscella tularensis (B)

Contact with rabbits

Rabbits

Source: http://uhavax.hartford.edu/bugl/histepi.htm

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