Microbial Diseases of the Cardiovascular & Lymphatic System PDF

MICROBIAL DISEASE OF THE CARDIOVASCULAR AND LYMPHATIC SYSTEM Our Lady of Fatima University – College of Pharmacy  Structure and Function of the Cardiovascular and Lymphatic Systems Structure of the Lymphatic and Cardiovascular Systems The heart, blood, and blood...

MICROBIAL DISEASE OF THE CARDIOVASCULAR AND LYMPHATIC SYSTEM Our Lady of Fatima University – College of Pharmacy  Structure and Function of the Cardiovascular and Lymphatic Systems Structure of the Lymphatic and Cardiovascular Systems The heart, blood, and blood vessels make up the cardiovascular system. Lymph, lymph vessels, lymph nodes, and lymphoid organs constitute the lymphatic system. Function of the Lymphatic and Cardiovascular Systems Plasma transports dissolved substances. Red blood cells carry oxygen. White blood cells are involved in the body’s defense against infection. Fluid that filters out of capillaries into spaces between tissue cells is called interstitial fluid. Interstitial fluid enters lymph capillaries and is called lymph; vessels called lymphatics return lymph to the blood. Lymph nodes contain fixed macrophages, B cells, and T cells.  Bacterial Diseases of the Cardiovascular and Lymphatic Systems  Sepsis and Septic Shock Sepsis is an inflammatory response caused by the spread of bacteria or their toxin from a focus of infection. Septicemia is sepsis that involves proliferation of pathogens in the blood. Gram-negative sepsis can lead to septic shock, characterized by decreased blood pressure. Endotoxin causes the symptoms. Antibiotic-resistant enterococci and group B streptococci cause gram-positive sepsis. Puerperal sepsis begins as an infection of the uterus following childbirth or abortion; it can progress to peritonitis or septicemia. Streptococcus pyogenes is the most frequent cause of puerperal sepsis. Oliver Wendell Holmes and Ignaz Semmelweiss demonstrated that puerperal sepsis was transmitted by the hands and instruments of midwives and physicians. Bacterial Infections of the Heart The inner layer of the heart is the endocardium. Subacute bacterial endocarditis is usually caused by alpha- hemolytic streptococci, staphylococci, or enterococci. The infection arises from a focus of infection, such as a tooth extraction. Preexisting heart abnormalities are predisposing factors. Signs include fever, weakness, and heart murmur. Acute bacterial endocarditis is usually caused by Staphylococcus aureus. The bacteria cause rapid destruction of heart valves.  Rheumatic Fever Rheumatic fever is an autoimmune complication of streptococcal infections. Rheumatic fever is expressed as arthritis or inflammation of the heart. It can result in permanent heart damage. Antibodies against group A beta-hemolytic streptococci react with streptococcal antigens deposited in joints or heart valves or cross- react with the heart muscle. Rheumatic fever can follow a streptococcal infection, such as streptococcal sore throat. Streptococci might not be present at the time of rheumatic fever.  Rheumatic Fever Prompt treatment of streptococcal infections can reduce the incidence of rheumatic fever. Penicillin is administered as a preventive measure against subsequent streptococcal infections.  Tularemia Tularemia is caused by Francisella tularensis. The reservoir is small wild mammals, especially rabbits. Signs include ulceration at the site of entry, followed by septicemia and pneumonia.  Brucellosis Also known as undulant fever Brucellosis can be caused by Brucella abortus, B. melitensis, and B. suis. The bacteria enter through minute breaks in the mucosa or skin, reproduce in macrophages, and spread via lymphatics to liver, spleen, or bone marrow. Signs include malaise and fever that spikes each evening (undulant fever). Diagnosis is based on serological tests.  Anthrax Bacillus anthracis causes anthrax. In soil, endospores can survive for up to 60 years. Grazing animals acquire an infection after ingesting the endospores. Humans contract anthrax by handling hides from infected animals. The endospores enter through cuts in the skin, respiratory tract, or mouth. Entry through the skin results in a papule that can progress to sepsis. Entry through the respiratory tract can result in septic shock. Diagnosis is based on isolating and identifying the bacteria.  Gangrene Soft tissue death from ischemia (loss of blood supply) is called gangrene. Microorganisms grow on nutrients released from gangrenous cells. Gangrene is especially susceptible to the growth of anaerobic bacteria such as Clostridium perfringens, the causative agent of gas gangrene.  Gangrene C. perfringens can invade the wall of the uterus during improperly performed abortions. Surgical removal of necrotic tissue, hyperbaric chambers, and amputation are used to treat gas gangrene.  Systemic Diseases Caused by Bites and Scratches Pasteurella multocida, introduced by the bite of a dog or cat, can cause septicemia. Anaerobic bacteria infect deep animal bites. Cat-scratch disease is caused by Bartonella henselae. Rat-bite fever is caused by Streptobacillus moniliformis and Spirillum minus.  Vector-Transmitted Diseases Plague is caused by Yersinia pestis. The vector is usually the rat flea (Xenopsylla cheopis). Relapsing fever is caused by Borrelia spp. and transmitted by soft ticks. Lyme disease is caused by Borrelia burgdorferi and is transmitted by a tick (Ixodes). Human ehrlichiosis and anaplasmosis are caused by Ehrlichia and Anaplasma and are transmitted by Ixodes ticks. Typhus is caused by rickettsias, obligate intracellular parasites of eukaryotic cells.  Viral Diseases of the Cardiovascular and Lymphatic Systems  Burkitt’s Lymphoma Epstein-Barr virus (EB virus, HHV-4) causes Burkitt’s lymphoma. Burkitt’s lymphoma tends to occur in patients whose immune system has been weakened; for example, by malaria or AIDS.  Infectious Mononucleosis Infectious mononucleosis is caused by EB virus. The virus multiplies in the parotid glands and is present in saliva. It causes the proliferation of atypical lymphocytes. The disease is transmitted by the ingestion of saliva from infected individuals. Diagnosis is made by an indirect fluorescent- antibody technique. EB virus may cause other diseases, including cancers and multiple sclerosis. Other Diseases and Epstein-Barr Virus EB virus is associated with certain cancers and autoimmune diseases. Cytomegalovirus Infections CMV (HHV-5) causes intranuclear inclusion bodies and cytomegaly of host cells. CMV is transmitted by saliva and other body fluids. CMV inclusion disease can be asymptomatic, a mild disease, or progressive and fatal. Immunosuppressed patients may develop pneumonia. If the virus crosses the placenta, it can cause congenital infection of the fetus, resulting in impaired mental development, neurological damage, and stillbirth.  Chikungunya Fever The chickungunya virus, which causes fever and severe joint pain, is transmitted by Aedes mosquitoes. Classic Viral Hemorrhagic Fevers Yellow fever is caused by the yellow fever virus. The vector is the Aedes aegypti mosquito. Signs and symptoms include fever, chills, headache, nausea, and jaundice. Diagnosis is based on the presence of virus- neutralizing antibodies in the host. No treatment is available, but there is an attenuated, live viral vaccine.  Dengue Dengue is caused by the dengue virus and is transmitted by the Aedes mosquito. Signs are fever, muscle and joint pain, and rash. Severe dengue is characterized by bleeding and organ failure. Mosquito abatement is necessary to control the disease.  Emerging Viral Hemorrhagic Fevers Human diseases caused by Marburg, Ebola, and Lassa fever viruses were first noticed in the late 1960s. Ebolavirus is found in fruit bats; Lassa fever viruses are found in rodents. Rodents are the reservoirs for Argentine and Bolivian hemorrhagic fevers.  Hantavirus Hantavirus pulmonary syndrome and hemorrhagic fever with renal syndrome are caused by Hantavirus. The virus is contracted by inhalation of dried rodent urine and feces.  Protozoan Diseases of the Cardiovascular and Lymphatic Systems  Chagas Disease Also known as American Trypanosomiasis Trypanosoma cruzi causes Chagas disease. The reservoir includes many wild animals. The vector is a reduviid, the “kissing bug.”  Toxoplasmosis Toxoplasmosis is caused by Toxoplasma gondii. T. gondii undergoes sexual reproduction in the intestinal tract of domestic cats, and oocysts are eliminated in cat feces. In the host cell, sporozoites reproduce to form either tissue- invading tachyzoites or bradyzoites. Humans contract the infection by ingesting tachyzoites or tissue cysts in undercooked meat from an infected animal or contact with cat feces. Congenital infections can occur. Signs and symptoms include severe brain damage or vision problems.  Malaria The signs and symptoms of malaria are chills, fever, vomiting, and headache, which occur at intervals of 2 to 3 days. Malaria is transmitted by Anopheles mosquitoes. The causative agent is any one of four species of Plasmodium. Sporozoites reproduce in the liver and release merozoites into the bloodstream, where they infect red blood cells and produce more merozoites.  Leishmaniasis Leishmania spp., which are transmitted by sandflies, cause leishmaniasis. The protozoa reproduce in the liver, spleen, and kidneys. Leishmaniasis is treated with liposomal amphotericin B.  Babesiosis Babesiosis is caused by the protozoan Babesia microti and is transmitted to humans by ticks.  Helminthic Disease of the Cardiovascular and Lymphatic Systems  Schistosomiasis Species of the blood fluke Schistosoma cause schistosomiasis. Eggs eliminated with feces hatch into larvae that infect the intermediate host, a snail. Free- swimming cercariae are released from the snail and penetrate the skin of a human. The adult flukes live in the veins of the liver or urinary bladder in humans. Granulomas are from the host’s defense to eggs that remain in the body. Observation of eggs or flukes in feces, skin tests, or indirect serological tests may be used for diagnosis. Chemotherapy is used to treat the disease; sanitation and snail eradication are used to prevent it. Disease of Unknown Etiology  Kawasaki Syndrome Kawasaki syndrome is characterized by fever, rash, and swollen lymph nodes in the neck. The cause is unknown.  END OF DISCUSSION