Microbiology: A Systems Approach, 2 nd ed. Chapter 20: Infectious Diseases Affecting the...

Microbiology: A Systems Approach, 2nd ed.

Chapter 20: Infectious Diseases Affecting the Cardiovascular and

Lymphatic Symptoms

20.1 The Cardiovascular and Lymphatic Systems and Their Defenses

• Cardiovascular System– Blood vessels and heart– Moves blood in a closed circuit– Also known as the circulatory system– Provides tissues with oxygen and nutrients and

carries away carbon dioxide and waste products

The Heart• Divided into two halves, each half divided into an

upper and lower chamber• Upper chambers: atria; lower chambers:

ventricles• Covered by the pericardium• Three layers to the wall of the heart (from outer

to inner)– Epicardium– Myocardium– Endocardium

Figure 20.1

Figure 20.2

Lymphatic System

• One-way passage• Returns fluids from the tissues to the

cardiovascular system

Figure 14.10

Defenses of the Cardiovascular and Lymphatic Systems

• Cardiovascular system is highly protected, however, if microbes do invade they gain access to every part of the body

• Bloodstream infections are systemic infections; often with the suffix –emia– Viremia– Fungemia– Bacteremia – Septicemia (can lead to septic shock)

• Defenses in the bloodstream- leukocytes

20.2 Normal Biota of the Cardiovascular and Lymphatic Systems

• None• Some microorganisms may be present

transiently (filtering out of tissues) but they do not colonize the systems in the healthy state

20.3 Cardiovascular and Lymphatic System Diseases Caused by

Microorganisms• Endocarditis

– Inflammation of the endocardium– Usually refers to an infection of the valves of the heart– Acute and subacute, with similar symptoms (in subacute

the symptoms develop more slowly and are less pronounced)

– Fever, anemia, abnormal heartbeat– Sometimes symptoms similar to heart attack– Abdominal or side pain may be reported– Petechiae over the upper half of the body and under the

fingernails may be present– In subacute cases, may have enlarged spleen

Figure 20.3

Septicemias

• Occurs when organisms are actively multiplying in the blood

• Many different bacteria and a few fungi can cause this condition

• Fever- prominent symptom• Patient appears very ill, may have an altered mental

state, shaking chills, and gastrointestinal symptoms• Often exhibits increased breathing rate and respiratory

alkalosis• Low blood pressure

Plague• Three possible manifestations

– Pneumonic plague: respiratory disease– Bubonic plague

• Bacterium injected through a flea bite• Enters the lymph and is filtered by a lymph node• Infection causes inflammation and necrosis of the node• Results in a swollen lesion called a bubo, usually in the groin

or axilla• Incubation period: 2 to 8 days, ending with the onset of

fever, chills, headache, nausea, weakness, and tenderness of the bubo

– Septicemic plague: when the case progresses to massive bacterial growth in the blood

Figure 20.4

Figure 20.5

Figure 20.6

Tularemia• Sometimes called rabbit fever, because it has been

associated with outbreaks of disease in wild rabbits• Pathogen of concern on the lists of bioterrorism agents• Tick bites: most frequent arthropod vector• Incubation period of a few days to 3 weeks• Symptoms: headache, backache, fever, chills, malaise,

and weakness• Further symptoms tied to the portal of entry:

ulcerative skin lesions, swollen lymph glands, conjunctival inflammation, sore throat, intestinal disruption, pulmonary involvement

Lyme Disease

• Nonfatal• Evolves into a slowly progressive syndrome

that mimics neuromuscular and rheumatoid conditions

• Early symptom: rash a the site of a tick bite• Other early symptoms: fever, headache, stiff

neck, and dizziness• Second stage: cardiac and neurological

symptoms develop

Figure 20.7

Figure 20.8

Figure 20.9

Figure 20.10

Infectious Mononucleosis• Majority caused by Epstein-Barr virus (EBV)• Most of the remainder caused by

cytomegalovirus (CMV)• Sore throat, high fever, and cervical

lymphadenopathy• Long incubation period- 30 to 50 days• Also may exhibit a gray-white exudates in the

throat, skin rash, and enlarged spleen and liver• Sudden leukocytosis• Fatigue

Figure 20.11

Hemorrhagic Fever Diseases

• Caused by viruses in one of four families:• Arenaviridae• Filoviridae• Flaviviridae• Bunyaviridae

Yellow Fever

• Capillary fragility• Disrupts the blood-clotting system• Begins with fever, headache, and muscle pain• Sometimes progresses to oral hemorrhage,

nosebleed, vomiting, jaundice, and liver and kidney damage

Dengue Fever

• Usually mild• Sometimes it can progress to dengue

hemorrhagic shock syndrome• Causes severe pain in muscles and joints

Ebola and Marburg

• Related viruses, cause similar symptoms• Extreme manifestations of of hemorrhagic

events with extensive capillary fragility and disruption of clotting

• Patients bleed from their orifices, mucous membranes, and experience massive internal and external hemorrhage

• Often manifest a rash on the trunk in early stages

Lassa Fever

• Most cases asymptomatic• In 20% of the cases a severe hemorrhagic

syndrome develops• Chest pain, hemorrhaging, sore throat, back

pain, vomiting, diarrhea, and sometimes encephalitis

• Patients who recover often suffer from deafness

Nonhemorrhagic Fever Diseases

• Brucellosis– On the CDC list of possible bioterror agents– Bacteria is carried into the bloodstream by

phagocytic cells, creating focal lesions in the liver, spleen, bone marrow, and kidney

– Fluctuating pattern of fever accompanied by chills, profuse sweating, headache, muscle pain and weakness, and weight loss

Figure 20.12

Q Fever

• Abrupt onset of fever, chills, head and muscle ache, and occasionally a rash

• Sometimes complicated by pneumonitis, hepatitis, and endocarditis

Figure 20.13

Cat-Scratch Disease

• Symptoms start after 1 to 2 weeks• Cluster of small papules at the site of

inoculation• In a few weeks, lymph nodes swell and can

become pus-filled• Only about 1/3 of patients experience high

fever

Figure 20.14

Trench Fever

• Highly variable symptoms• 5- to 6-day fever• Leg pains, especially in the tibial region• Headache, chills, and muscle aches• Macular rash can occur• Endocarditis can develop

HGA and HME

• Similar signs and symptoms• Acute febrile state • Headache, muscle pain, and rigors

Rocky Mountain Spotted Fever (RMSF)

• 2 to 4 days incubation• First symptoms: sustained fever, chills,

headache, and muscular pain• Distinctive spotted rash within 2 to 4 days after

the prodrome• In most severe untreated cases, enlarged lesions

merge and become necrotic• Other manifestations: cardiovascular disruption;

conditions of restlessness, delirium, convulsions, tremor, and coma

Figure 20.15

Figure 20.16

Malaria

• The world’s dominant protozoan disease• 10- to 16-day incubation period• First symptoms: malaise, fatigue, vague aches,

and nausea with or without diarrhea• Next symptoms: bouts of chills, fever, and

sweating• Symptoms occur at 48- or 72-hour intervals• The interval, length, and regularity of symptoms

reflect the type of malaria

Figure 20.17

Figure 20.18

Figure 20.19

Anthrax

• Can exhibit its primary sumptoms in various locations of the body– Cutaneous anthrax– Pulmonary anthrax– Gastrointestinal tract– Anthrax meningitis

• Cutaneous and pulmonary forms most common

Figure 20.20

HIV Infection and AIDS• Retrovirus: human immunodeficiency virus

(HIV)– Hybrid virus- genetic sequences from two separate

monkey SIVs• The disease: acquired immunodeficiency

syndrome (AIDS)• Spectrum of clinical disease associated with HIV

infection• Symptoms directly tied to two things: the level

of virus in the blood and the level of T cells in the blood

Symptoms• Initial infection: vague, mononucleosis-like symptoms

that soon disappear (initial high levels of virus)– Within days, about 50% of the T helper cells with memory

for the virus are destroyed• Period of asymptomatic infection that varies in length

from 2 to 15 years– During this period the number of T cells in the blood is

steadily decreasing– Once T cells reach low enough levels, symptoms of AIDS

ensue• Initial symptoms of AIDS: fatigue, diarrhea, weight

loss, and neurological changes

Other Symptoms as the Disease Progresses

• Opportunistic infections or neoplasms• Severe immune deregulation, hormone

imbalances, metabolic disturbances• Pronounced wasting of body mass• Protracted fever, fatigue, sore throat, and

night sweats• Lesions in the brain, meninges, spinal column,

and peripheral nerves

Figure 20.21

Figure 20.22

Figure 20.23

Figure 20.24

Figure 20.25

Adult T-Cell Leukemia and Hairy-Cell Leukemia

• Leukemia: general name for at least four different malignant diseases of the WBC forming elements originating in the bone marrow

• Some acute, others chronic• Many causes- two of which are thought to be

viral– Adult T-cell leukemia by HTLV-I– Hairy-cell leukemia by HTLV-II

• Signs and symptoms include easy bruising or bleeding, paleness, fatigue, and recurring minor infections