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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