Microbial cardiovascular and systemic disease

Cardiovascular system and septicemia

Blood is normally axenic, it contains no microbes

Septicemia refers to microbial infection of the blood which can lead to septic shock

Depending on the type of organism, blood infections are referred

to as: *Bacteremia (bacterial septicemia) Viremia Fungemia Parasitemia

Petechiae – sign of bacteremia

Bacteria can release toxins from a site of infection into the blood causing toxemia Exotoxins: i.e., neurotoxins (botulism/tetanus) Endotoxins: lipid A of LPS, which can lead to shock

Severe form of toxemia with septic shock Streptococcal toxic-shock-like syndrome (TSLS)

Streptococcus pyogenes From infections of skin/wound

Staphylococcal toxic shock syndrome (TSS) Staphylococcus aureus

From reproductive tract infections

Cardiovascular system and septicemia

Bacterial septicemia can be associated with Infections of the skin/wound Surgical wounds Urinary tract infections Infected teeth Improperly sterilized kidney dialysis machines, ….

Caused by opportunistic or nosocomial bacteria such as Escherichia coli, Pseudomonas aeruginosa, Neisseria meningitidis,

Haemophilus influenzae Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus

pyogenes

Cardiovascular system and septicemia

Diagnosis of septicemia involves analysis of signs/symptoms Culturing bacteria from the blood

In occult septicemia the exact bacterial cause is hidden

Treatment involves Use of antimicrobial drugs

Elimination of the initial site of infection (source of

septicemia)

Intravenous fluid replacement/Antibodies against LPS Toxemia caused by Gram negative bacteria

Cardiovascular system and septicemia

Blood and lymph can carry pathogens throughout the body to cause systemic disease Bacterial

Tularemia Plague Lyme disease

Viral EBV (Epstein-Barr Virus) Cytomegalovirus

Protozoan Toxoplasmosis Malaria Chaga’s disease

Helminths Schistosomiasis

Microbial systemic disease

Bacterial systemic diseases - Tularemia

Tularemia is a zoonotic disease caused by Francisella tularensis (Gram-negative coccobacillus)

Virulence (endotoxin and lipid capsule – resists phagocytosis)

Prevalence in animals as intracellular parasite: from mammals (rabbit ), to birds, fish, ticks, flies, mosquitoes, mites

Multiple mode of transmission bite of a tick contact with infected animal/animal

slaughter contaminated meat or water aerosols produced in the laboratory

Mortality rate: ~ 5% of untreated patients

Bacterial systemic diseases - Tularemia

Highly virulent organism that causes

Skin lesion (ulcer) and swollen pus-filled lymph nodes near the site of infection, lymphangitis

General symptoms may last for months/years malaise, fatigue, joint

stiffness, myalgia

Diagnosis/treatment Serological testing Antimicrobials Vaccine for people at risk

Possible use of Francisella as bioterrorism weapon – nationally notifiable disease (CDC)

Plague – Yersinia pestis (Enterobacteriaceae)

Bubonic plague - bite of infected flea or direct contact with infected animal

Pneumonic plague - bacilli spread from the blood to the lungs or are inhaled (airborne transmission)

Plague has caused several pandemics

Xenopsylla cheopis

Plague – Yersinia pestis

Bubo: painfully inflamed lymph node

Darkening of dead tissues

Plague has been called the “Black Death”

Bubonic plague is fatal in ~50% of cases if untreated

Pneumonic plague is fatal in ~100% of cases if untreated

Urban living, rodent and flea control, antibacterial drugs have almost eliminated plague

The disease is considered endemic in states like California, Arizona, Nevada

Potential bioterrorism weapon: deadly, progresses rapidly, spread among people

Lyme disease (zoonosis)

Caused by the spirochete Borrelia burgdorferi

Gram negative

Bull’s eye rash at the site of

infection

Untreated patients can develop severe arthritis

Lyme disease is transmitted by a deer tick (Ixodes)

Deer tick: a 2-years life cycle

Lyme disease

Increase in cases of Lyme disease

Diagnosis: detecting antibodies against Borrelia

Antimicrobial drugs can cure the Lyme disease (first phase)

Treatment of later phases involves anti-inflammatory drugs

Viral systemic diseases – Epstein Barr virus (EBV)

HHV-4 Implicated with several diseases, depending on the “relative vigor”

of a host’s cellular immune response

EBV and infectious mononucleosis

EBV is transmitted via saliva, enters the blood and infects B cells, which become enlarged with lobed nuclei

Cytotoxic T cells kill infected B cells

Signs and symptoms: fever, sore throat, fatigue, enlarged lymph nods and spleen

Diagnosis: detecting antibody against EBV Recover of most patients in few weeks without

specific therapy

EBV can become latent in the oropharynx: life long infection which rarely cause disease

Cytomegalovirus (CMV) – Herpes virus

Most people infected with CMV are asymptomatic

CMV remains in a latent state in various cells

Complications in

Immunocompromised patients

May develop pneumonia, blindness,

CMV mononucleosis

Fetuses (may be teratogenic)/newborns

~7.5% of neonates infected with CMV

Bodily secretions carry CMV (saliva, mucous, milk, urine, feces, semen, vaginal secretions) – it would require a large exchange of secretions

Cytomegalovirus (CMV) – herpes virus

CMV infections is one of the most common infections in humans

Transmission usually occurs via

Sexual intercourse

Prenatal infection

Vaginal birth

Blood transfusion

Organ transplants

Diagnosis/Treatment involve

Owl’s eye appearance of enlarged cells, detection of CMV and antibodies against CMV

Interferons, anti CMV immunoglobulins, fomivirsen against replication of CMV in retinal cells. There is no vaccine against CMV

Protozoan diseases – Toxoplasmosis

Toxoplasma gondii Nucleated cells of wild and

domesticated mammals, birds

Immunocompromised patients can develop the disease Fever, inflammation of several organs, spastic paralysis,

blindness, encephalitis, and death

Transplacental infections – (first-trimester at higher risk) can cause spontaneous abortion, mental retardation, blindness, or microcephaly

Healthy individuals (mostly asymptomatic) Infection normally resolves

without treatment

Humans become infected when ingesting undercooked contaminated meat

Serological detection and microscopic identification in tissue samples

Treatment with a combination of drugs in AIDS patients, pregnant women, newborns

Wash fruits and vegetables, eat well cooked meat!!!

Protozoan diseases – Toxoplasmosis Definitive host

Malaria is transmitted by Anopheles mosquito

Plasmodium species, including P. falciparum (blackwater fever)/P. vivax (chronic malaria)

Malarial paroxysms: cycles of

fever-chills correlate with period of erythrocyte lysis

Anemia and jaundice

(liver/eyes)

Protozoan diseases - Malaria

Ring-stage - trophozoites within red blood cells

Microscopic examination of blood smears allows diagnosis of malaria

Serological tests for specific diagnosis

Treatment and supportive measures Antimalarial drugs Anti-fever medication Blood transfusions

Alternative methods involve

Limiting contact with mosquitos carrying Plasmodium

Malaria vaccines (development and testing in progress)

Protozoan diseases - Malaria

Malaria is endemic throughout the tropics and subtropics, where Anopheles breeds

Mosquito eradication programs eliminated the disease in Countries like US

Over 500 million people are infected

1-3 million people die annually

Chagas’ disease – American trypanosomiasis

Caused by Trypanosoma cruzi Transmitted with the feces of the bloodsucking “kissing bug”

Major reservoirs: opossum and armadillos though most mammals, including humans, can carry the parasite

~ 1% of infected humans develop early stages (general symptoms)

Intermediate asymptomatic (chronic) stage for up to ~ 20 years

Heart failure during final symptomatic stage Clusters of parasites in the

heart muscle tissue

Trypomastigotes (infective) circulating in the blood are ingested by the kissing bug

Chagas’ disease – American trypanosomiasis

The disease is endemic in Central and South America

Affects 8-15 million people Thousands die each

year, including children

Early stages can be treated but not late stages

No vaccine exists for Chagas’s disease

Prevention involves measures that protect against bugs: mud replaced with concrete/brick, insecticides …..

Schistosomiasis is caused by blood flukes

Genus Schistosoma The larval stage cercaria burrows into the skin Feeding on blood, matures, mates, and releases eggs Eggs lodge in tissues causing damage to several organs

Treatment/control: drugs that kill the worm in the body, sewage treatment, and snail suppression

Egg of Schistosoma mansoni

Diagnosis: identification of eggs - shape of the egg and location of the spines - in stool or urine samples

WHO (World Health Organization) estimates that over 250 million people are infected worldwide – Asia, Africa, South America

Schistosomiasis is caused by blood flukes

Scarlike tissue surrounds the egg