Infections of the Blood andBiological Weaponry

Lesson Objectives• Describe and list the major defenses of the cardiovascular

and lymphatic systems against infectious disease.

• Explain why infections of the cardiovascular and lymphatic systems pose such a serious health concern to patients.

• Discuss the epidemiology, progression, and prevention of septicemia.

• Discuss the epidemiology, progression, and treatment of HIV disease and AIDS.

• Discuss public health considerations of biological weapons, in terms of characteristics of biological weapons, health care provider considerations, and public information concerns.

The Circulatory and Lymphatic Systems

• Circulatory system: circulates an adult within 3 minutes. Provides every cell with food and oxygen, removes wastes and CO2.

• Lymphatic system: open part of the circulatory system that returns fluid from interstitial tissue to the blood.

• Both systems form the major components of the Second and Third Lines of Defense.

• Neither system is normally colonized with microbes, but it is believed that even during states of health, there are transient microbes present. These transient microbes are eliminated through phagocytosis, T cell interactions, and antibody activity.

• Because the bloodstream and the lymphatic system communicate with all parts of the body rapidly, an infection of blood or lymph is a major medical concern. Any bacteria isolated from a blood culture or a body fluid culture is identified and reported. Antibiotic sensitivities are also reported as appropriate.

Septicemia, Sepsis, Blood Poisoning• Septicemia is an infection of the blood.

“fulminating” means organisms are actively reproducing in the blood.

• Symptoms: any of these may occur suddenly

- fever- tachycardia- hyperventilation (respiratory alkalosis)- chills- altered mental state- hypotension (severe)

Complications of septicemia

• Shock (caused by LPS of Gram negative bacteria)• Organ failure (respiratory arrest, cardiac arrest,

kidney failure)• Disseminated intravascular coagulation (DIC)

Random clots form in the peripheral circulatory system. This causes impaired blood flow and random hemorrhaging or bleeding out (why hemorrhaging?)

Causative agents of septicemia:

Name it!!!! Any bacteria and many fungi may be a cause of septicemia.

How do these organisms enter the bloodstream?

Treatment of septicemia:

• Antibiotics

HIV infection and Acquired Immune Deficiency Syndrome (AIDS)

Human Immunodeficiency Virus (HIV) is a retrovirus (RNA that forms a DNA intermediate) that attacks T helper cells and macrophages.

Signs and symptoms: Early infection:

- unexplained fatigue and flu-like symptoms (muscle and joint soreness)

- swollen lymph nodes (neck, groin, other places)

- transient fever

- “night sweats”

- diarrhea

- mouth/genital ulcers or rash

Progression of HIV infection—see figure 18.2 on page 499.

1. Acute stage of infection: 2-4 weeks after infection. Virus particles increase rapidly, patient experiences severe flu-like symptoms (“worst flu ever”). Viral concentration drops afterward to “viral set point” where it may remain for years.

2. Latent stage of infection: May last for up to 10 years. Virus is present, but at low levels. During this period, it may be attacking T helper cells, gradually reducing their numbers.

From Nature 2003

Normal CD4 levels in the blood are 500-1200 cells/ml. The viral load spikes early in the infection, then drops. Even at low levels, damage to CD4 cells occurs.

Progression of the infection by CD4 levels

• HIV related illness: CD4 levels are 200-500 cells/ml.

Opportunistic infections begin to appear:

- oral Candida yeast infection (thrush)—may affect eating.

- cervical dysplasia

- bacillary angiomatosis (lesions, internal and external)

- oral hairy leukoplakia (painless white plaque in the mouth, on the tongue)

- complications of Varicella zoster (shingles) and Epstein-Barr virus

CD4 levels below 200 cells/ml: defines AIDS

AIDS is also defined by infection with the following (at any CD4 count):• Pneumocystis jiroveci pneumonia (PCP)• Cryptococcus neoformans meningitis• Kaposi’s sarcoma• Toxoplasmosis encephalitis• MAI/MAC (Mycobacterium avium)• cytomegalovirus

Diagnosis of HIV

• Early: ELISA—screen for HIV antibodies. Positive test is confirmed by Western blot (alternative antibody test)

• CD4 test: absolute numbers and relative (normal percentage of lymphocytes = 40 %)

• Viral load: concentration of HIV in the blood stream.

Transmission of HIV• HIV is transmitted in semen, blood, vaginal fluids, body fluids, breast

milk.

• Although it has been identified in these, HIV has not been contracted through urine, saliva, tears, or sweat.

• Modes of transmission:- sexual activity that involves transmission of materials indicated above.

- transfer of blood or blood products

- vertically, from mother to infant, through pregnancy, birth, or breast feeding.

HIV treatment• CDC recommends HIV treatment when CD4 levels are 350

or less.• HAART: Highly Active Anti-Retroviral Therapy

This is an approach to managing HIV infection at any stage. It involves combining several approaches to attacking the HIV:

- prevent viral replication- prevent viral attachment (protease inhibitors)- prevent viral release.

Many of these treatments reduce viral numbers enough to allow CD4 numbers to increase. Result: some HIV patients live 20+ years without noticeable symptoms.

Biological Weaponry

• The use of microbes to intentionally cause illness or death.

• An old concept: 1345: The Mongols of Kaffa battled the Italian army by catapulting corpses of victims of bubonic plague. May have started the “Black Death” in Europe.

1763: Jeffrey Amherst is reported to send smallpox infected blankets to Native Americans (the truth of this story is under dispute).

The CDC identifies three categories of critical biological agents.

What are the characteristics of a biological agent that would pose the greatest risk to national security?

CDC’s list:

• Easily transmitted to large numbers of people.

• High mortality

• Difficult to treat (highly resistant to treatment, antidotes or resources in limited supply)

• Easily available/cheap

Top agents of Biological Weaponry of concern:

• Anthrax: Bacillus anthracis

- Gram positive rod, endospore former

- causes pneumonia (pulmonary), skin lesions (cutaneous) or meningitis.

- lab identification problematic—culture results resemble common contaminants.

- can be treated with antibiotics—vaccine available.

Botulism

• Produced by Clostridium botulinum (endospores)

• Toxin is the most toxic substance to humans produced by a living organism.

• Symptoms appear 12-36 hours after ingestion. Early symptoms resemble the flu.

• Vaccine available.

Plague/Tularemia• Both caused by bacteria (fairly rare)

plague: Yersinia pestistularemia: Francisella tularensis

• Both caused by bite from an arthropod vectorplague: flea bitetularemia: tick or deerflyboth also can be inhaled.

• Symptoms: flu like symptoms, swollen lymph nodes, followed by hemorrhaging and death.

• Both can be treated with antibiotics.

So, Homeland Security has issued an alert that there is a potential for a BW.

As a nurse, what would your major concerns be?