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-spirochetes
-Louse-borne relapsing fever
-transmitted to humans by the human body louse (lice)
-recurring episodes of septicemia and fever
-doxycycline or erythromycin -bull's eye rash
-spirochetes
-Tick-borne relapsing fever
-soft ticks
-ticks and rodents can be reservoirs
-recurring episodes of septicemia and fever due to body trying to remove the spirochetes
-doxycycline or erythromycin
-results from ingestion of shellfish
-causes cholera-like gastroenteritis
-septicemia due to consumption of contaminated shellfish
-wound infections can result from washing wounds with contaminated seawater
-most common cause of gastroenteritis in the United States -slightly curved, oxidase positive, and motile
-microaerophilic: grows in low O2 and capneic: thrives in high CO2 (how it differs from vibrios)
-zoonotic disease --> poultry, cattle, dogs/cats -adhesins, cytotoxins, and endotoxins
self-limiting bloody and frequent diarrhea
-virus moves via the blood to the skin, where it produces
-scars result on the skin, especially on the face (lesions)
-infects internal organs, causing fever, malaise, and delirium
macule
papule
vesicle
pustule
crust
scar
-the first human disease to be eradicated
Factors that enabled the eradication of smallpox
Inexpensive, stable, and effective vaccine
No animal reservoirs
Obvious symptoms allow for quick diagnosis and in quarantine
Lack of asymptomatic cases
Virus is only spread via close contact
Stocks of the virus are maintained in laboratories in the U.S. and Russia
-skin disease characterized by pearly white to light pink, smooth, waxy papules (appear tumor-like)
-typically on face, trunk, and external genitalia
-spread by children, sexually active ppl, or ppl AIDS
-treatment by removing nodules
-causes chicken pox, found in children
-or causes shingles in adults
-chicken pox is highly infectious disease
-virus enters skin through the respiratory tract or eyes
-characteristic skin lesions (dew drops on rose petals)
-characteristic localization of shingle lesions along a band of skin, called a dermatome
-transmission occurs via saliva
-large lobed B lymphocytes with atypical nuclei and neutropenia are characteristic features of infection
-causes:
-oral hairy leukoplakia,
-burrito's lymphoma,
-nasopharyngeal cancer,
-chronic fatigue syndrome,
-Burkitt's lymphoma: swollen jar
-infectious mononucleosis: swollen lymph nodes
-infected cells become abnormally enlarged (owl’s eye)
-transmission occurs through bodily secretions
-requires close contact and a large exchange of secretion
--(sexual intercourse, in utero exposure, vaginal birth, blood transfusions, and organ transplants)
-complications in fetuses, newborns, and immunodeficient patients
-treatment: Fomiversen for eye infections
-causes roseola
-characterized by pink rash on face, neck, trunk, and thighs
-may be linked to multiple sclerosis
-can cause mononucleosis-like symptoms
-may make individuals more susceptible to AIDS
-associated with Kaposi’s sarcoma, a cancer often seen in AIDS patients
-it is a rare and malignant neoplasia of blood and blood vessels
-causes warts
--seed warts, plantar warts, flat warts, genital warts (condylomata acuminata)
-genital warts associated with an increased risk of cancer
-transmitted via direct contact and via fomites
-diagnose cancers by inspecting genitalia and by a PAP smear
-gardasil vaccine (three doses for all females 11-26 yrs of age) effective against most strains of cervical cancer
-capable of causing tumors in animals and humans
--BK virus: potentially severe urinary tract infections can develop
--JC virus: can cause progressive multifocal leukoencephalopathy in which viruses can infect and kill oligodendrocytes of CNS
-contain single, linear dsDNA genome contained in a naked polyhedral capsid with spikes
-one of many causative agents of the “common cold”
-respiratory infections
-infection of the intestinal tract can produce mild diarrhea
-infection of the conjunctiva can result in pinkeye
-gamma interferon treatment
-causes hepatitis (inflammation of the liver)
-the only DNA virus that causes hepatitis
-jaundice, a yellowing of the skin and eyes, occurs when bilirubin accumulates in blood
-liver cells continually release virions into the blood
-virions are shed into saliva, semen, and vaginal secretions
-transmitted when infected body fluids contact breaks in the skin or mucous membranes
-can lead to liver cancer
-virus spread through infected needles, sex, and passage to babies
-diagnose by detecting presence of viral antigens
--dane, spherical, and filamentous particles for diagnosis
-alpha-interferon treatment
-liver transplant required for end-stage chronic disease
-3 doses of vaccination
-only human pathogen with a ssDNA genome
-smallest of the DNA viruses
-B19 virus is the primary parvovirus of humans
--causes erythema infectiosum
-results in a reddening of the skin beginning on cheeks
-also called fifth disease or slapping disease
-the other four diseases that cause rashes are scarlet fever, rubella, roseola, and measles
-sunlight aggravates condition
have a segmented genome: more than one molecule of RNA
-naked, +ssRNA viruses
-smallest of the animal viruses
-comprises of several genera: enterovirus, hepatovirus and rhinovirus
-cause most cases of the common cold (along with adeno-, corona-, reo-, & paramyxoviruses)
-infections limited to the upper respiratory tract (33°C)
-a single virus is often sufficient to cause a cold
-pleconaril can reduce the severity and duration of colds
-handwashing!!
-transmitted via the fecal-oral route -ingestion of contaminated food or water -infect the pharynx and intestine -cytolytic -three main viruses: --polioviruses, coxsackieviruses, and echoviruses
-causes poliomyelitis
--asymptomatic infections (almost 90%)
--minor polio (5%): fever, headache, sore throat
--nonparalytic polio (2%)
--paralytic polio (less than 2%)
---bulbar poliomyelitis (brain stem and medulla are infected)
--postpolio syndrome 2 vaccines:
-inactivated polio vaccine (IPV)
-oral polio vaccine (OPV)
-naked, +ssRNA virus
-noncytolytic picornavirus
-transmitted through the fecal-oral route
-signs and symptoms: fever, nausea and jaundice are due to the patient’s immune response
-does NOT cause chronic liver disease
-enteric: contaminated food/water/etc
-two doses are recommended for all children and adults
-naked, +ssRNA virus
-star-shaped polyhedral capsids
-causes acute gastroenteritis
-outbreaks in day care centers, schools, hospitals, cruise ships
-best known virus is: Norovirus --causes diarrhea, nausea and vomiting
-incubation period is 24 hrs
-naked, +ssRNA virus
-also known as enteric hepatitis
-fatal in 20% of pregnant women
-prevent by interrupting the fecal-oral route of transmission
-enveloped, +ssRNA virus
-designated as Arboviruses (Arthropod-borne)
-mosquitoes and ticks transmit arboviruses among animal hosts causing zoonotic diseases
-arthropod vectors remain infected
-most infections result in mild, flu-like symptoms
-enveloped, +ssRNA virus
-equine encephalitises
-eastern equine encephalitis (EEE)
-western equine encephalitis (WEE)
-venezuelan equine encephalitis (VEE)
-viral replication occurs in horses and humans
-normal host is a bird or rodent
-mosquitoes are vectors
Rubella virus (Togaviridae)
-enveloped, +ssRNA virus
-also called “German measles” or “three day measles” (mild)
-one of the five childhood diseases that produces skin lesions (other four are measles, roseola, chickenpox, fifth disease)
-infection begins in respiratory system but spreads throughout the body
-rash of flat, pink to red spots
-not serious in children, but adults can develop arthritis or encephalitis
-infection of pregnant women can cause congenital defects
-vaccination
-enveloped, +ssRNA virus
-causes West Nile Encephalitis
-flu-like symptoms and encephalitis after being bitten by mosquitoes
-Aedes mosquito transmits virus that causes dengue fever
-first phase of high fever and severe pain in head, neck and muscles (breakbone fever)
-second phase: return of fever and bright red rash
-reinfection causes dengue hemorrhagic fever
Yellow fever virus (Flaviviridae)
-involves degeneration of the liver, kidneys, heart and massive hemorrhaging resulting in “black vomit”
Chickengunya virus (Flaviviridae)
-rash, nausea, joint pain
Zika virus (Flaviviridae)
-fever, rash, joint pain, microencephaly
-diagnosis by serological tests like ELISA and agglutination test
-prevention by vaccination for Yellow fever
-no vaccine
-enveloped, +ssRNA virus
-spread through needles, organ transplants, and sexual activity but not by arthropod vectors
-chronic infection with few if any symptoms
-severe liver damage and liver failure can occur over time
-sofosbuvir (inhibits protease) cures most people within 12 weeks
-no vaccine
on lung, heart, brain, kidney, gastro-intestinal cells as well as cells of blood vessels and testis
-promotes viral reuptake and fusion at the cellular membrane
monoclonal antibody therapy:
-Eli Lily and Co
-Regeneron
-Mabs
Antivirals: -Remdesivir: nucleoside analog and inhibits the RNA-dependent RNA polymerase -Ritonavir (oral) -Molnupiravir increases the frequency of viral RNA mutations and impairs replication
-enveloped, +ssRNA viruses with reverse transcriptase
-genomes contain two identical molecules of positive ssRNA and contain the enzymes reverse transcriptase, protease, and integrase
-transcribe dsDNA from ssRNA using reverse transcriptase
--Human T-lymphotrophic viruses: cancer of lymphocytes
-Lentivirus human immunodeficiency viruses (HIV-1 & 2)
-certain opportunistic or rare infections that occur in the presence of antibodies against HIV and a CD4 white blood cell count below 200 cells/microliter of blood
Measles virus (Paramyxoviridae)
-spread in the air via respiratory droplets
-viruses infect the respiratory tract then spread throughout the body
-koplik’s spots appear on the mucous membrane of the mouth
-lesions then appear on the head and spread over the body -rare complications can result in:
pneumonia, encephalitis, and subacute sclerosing panencephalitis (SSPE)
-MMR vaccine
-anti-viral immunoglobulin for prevention
-causes croup: severe condition characterized by inflammation of larynx, trachea, bronchi, and a “seal bark” cough
--most patients recover within two days
Mumps virus
-transmission occurs via respiratory secretions -causes parotitis: painful enlargement of the parotid salivary glands --orchitis (inflammation of the testicles), meningitis, pancreatitis, or deafness in one ear can occur -MMR vaccine
Respiratory syncytial virus) - RSV
(Pneumovirus)
-causes a disease of the lower respiratory tract, particularly in children
-transmission occurs via fomites, hands, and respiratory droplets
-the virus causes syncytia formation in the lungs
-infection can also result in difficult breathing known as dyspnea
-leading cause of fatal respiratory disease in infants and children (day care centers)
-treatment is supportive-oxygen or ribavrin
-enveloped, unsegmented -ssRNA viruses
-bullet-shaped
-classical zoonotic disease of mammals
-primary reservoir in urban areas is the dog
-bats are the source of most cases in humans
-specific neurological manifestations: hydrophobia, seizures, disorientation, hallucination, paralysis
-diagnosed by finding Negri bodies in the brain
-treatment by immune globulin (HRIG) or vaccination with human diploid cell vaccine (HDCV) at days 0, 3, 7 and 14 days after exposure
-enveloped, unsegmented -ssRNA viruses
-causes hemorrhagic fever -
form long filaments
-biosafety level 4 pathogens (BSL4)
-found in Germany, Zimbabwe, Kenya, Uganda, Angola
-natural reservoir is fruit bats
-spreads via direct contact with bodily fluids including semen and wastes of its victims
-virions attack many cells, especially macrophages and liver cells
-causes uncontrolled bleeding under the skin and from every body opening
-up to 90% of human victims die if left untreated
-ELISA test or PCR for diagnosis
-ZMapp antiviral treatment which is antibodies against the virus
Influenza types A and B (Orthomyxoviridae)
-enveloped, segmented -ssRNA viruses
-infection occurs primarily through inhalation of airborne viruses
-symptoms include fever, pharyngitis, congestion, dry cough, malaise, headache, and myalgia
--induced by cytokines released as part of the immune response -each virion is segmented, having 8 different –ssRNA molecules (variable)
-hemagglutinin (HA) glycoprotein spikes
--attach to pulmonary epithelial cells or trigger endocytosis
-neuraminadase (NA)
--provide the virus access to cell surfaces by hydrolyzing the mucus in the lungs
-minor variations -consists of small changes (or mutations) in the genes of influenza viruses that can lead to changes in the surface proteins of the virus, HA (hemagglutinin) and NA (neuraminidase)
-slight changes
-one strain enters
-you will have most of the antibodies (70%) if reinfected
-major variations -the process by which two or more different strains of a virus, or strains of two or more different viruses, combine to form a new subtype having a mixture of the surface antigens of the two or more original strains
-2 different strains enter
-completely different new 3rd strain
-no antibodies against this strain
-sudden fever, pharyngitis, congestion, cough, headache, myalgia
-viruses enter the body via the respiratory route
-incubation period is about one day
-for treatment: oseltamivir pills or inhaled zanamivir mist are neuraminidase inhibitors
--must be administered within first 48 hours of infection
-prevention: immunization with multivalent vaccines
-enveloped, segmented -ssRNA viruses
-transmitted through bodily fluids via sexual activity and contaminated needles
-requires hepatitis B virus to be virulent because this virus can’t attach to liver cells
-plays a role in triggering liver cancer
-vaccination against hepatitis B limits spread of this virus
-only double stranded RNA
-most common cause of infantile gastroenteritis, unique wheel-like appearance
-transmitted via the fecal-oral route
-significant cause of death in developing countries
-most common fungal pathogen affecting humans
-intracellular parasite and is phagocytosed by alveolar macrophages
-mostly in the eastern United States (Ohio river valley) but also in Africa and South America
-fungi found in moist soils containing high nitrogen levels (bird and bat droppings in soil)
-inhalation of spores into the lungs
-endemic in the southeastern United States north to Canada
--pulmonary condition is the most common manifestation
-symptoms vague like muscle aches, cough, fever, chills, and weight loss
-other conditions:
--cutaneous condition (spread from lungs to skin); osteoarticular condition, meningitis
-diagnosis is by observation of dimorphism in lab culture (large round budding yeast)
-almost exclusively in the southwestern United States & Northern Mexico (California, Nevada, Arizona, New Mexico, Texas)
-found in desert soil
-if inhaled, asexual spores called arthroconidia germinate into spherules (encapsulated yeasts) in the lung
-most often result in pulmonary conditions
-diagnosis by coccidiodin skin test
-treatment by Amphotericin B; maintenance with azoles
-found in cool damp soil of southern Mexico and regions of South America
-disease found most in farm workers in endemic areas
-painful ulcerated lesions of gums, tongue, lips, and palate
-diagnosis: staining reveals yeast cells with multiple buds in a “steering wheel” formation
-treatment is with amphotericin B or ketoconazole
-causes cysts in lung tissue
-presence of the disease is almost diagnostic for AIDS
-inflammation, fever, difficulty in breathing and non productive cough are characteristic
-can result in death if left untreated
-treatment: trimethoprim and sulfanilamide
-includes various opportunistic infections and diseases
-common members of microbiota of skin and mucous membranes
-transmitted between individuals
-can be passed on to babies during childbirth or to men during sexual contact
-can produce a wide range of diseases
• oropharyngeal condition or thrush (oral)
• diaper rash
• nail infection (onychomycosis)
• ocular condition
• vaginal condition: if pH becomes alkaline, or after antibiotic therapy
-diagnosis: clusters of budding yeast and pseudohyphae (series of buds remaining attached to the parent cell)
-treatment : nystatin, azoles
-results from inhalation of spores or dried yeast in bird droppings
-predilection for the central nervous system
meningitis condition • most common clinical form of infection • follows dissemination of the fungus to the CNS -other clinical manifestations- pulmonary or cutaneous conditions -diagnosis: presence of a phagocyte resistant capsule surrounding the yeast form is highly suggestive --yeasts multiply in the lungs and spread to other parts of the body
-infections confined to the outer, dead layers of the skin, nails, hair
--keratin primary food of these fungi
-black and white piedra (stone-like) are superficial infections of the hair shafts
-dermatophytoses
• fungal infections of the skin, nails, or hair caused by dermatophytes
• variety of clinical manifestations like athlete’s foot, jock itch, onychomycosis
-pityriasis: infection of the skin causing disruption of melanin production to produce discolored patches: caused by Malassezia furfur
-mycetomas: tumor-like infections
-sporotrichosis (rose-gardener’s disease)
• acquired from inoculation of soil fungi by thorn pricks
-protozoa that use cilia in their trophozoite stage
-only known ciliate known to cause disease in humans
-commonly found in animal intestinal tracts
-humans infected by food or water contaminated with feces containing cysts
-trophozoites attach to mucosal epithelium lining the intestine
-causes infection in people with lowered immune health
• persistent diarrhea, abdominal pain, and weight loss
• severe infections produce dysentery
-presence of trophozoites diagnostic
-treatment: tetracycline
-carried asymptomatically in the digestive tracts of humans -infection occurs by drinking water contaminated with feces containing cysts
-three types of amebiasis can result from infection
luminal amebiasis
invasive amebic dysentery (bloody mucus stools and
pain)invasive extraintestinal amebiasis -presence of trophozoites in fecal smear used for diagnosis -active stage that exists in host and in fresh loose feces -prevention: safe drinking water;
-contracted by food or water contaminated by cysts which then hatched and invaded his large intestine
-treatment: paromomycin or iodoquinol
-infection occurs when swimmers inhale contaminated water
-unchlorinated water, Neti pots
-amoebic meningoencephalitis can result
-“brain-eating amoeba”
-diagnosis by detection of trophozoites in corneal scrapings, CSF
-prevention difficult since organisms are environmentally hardy
-causes Chagas’ disease; is endemic in Central and South America
-opossums and armadillos are the primary reservoir
-transmission occurs through bite of insects in genus Triatoma
-"kissing bugs” feed preferentially from blood vessels in the lips
-acute stage characterized by chagomas (swellings at the bite site)
-symptomatic stage characterized by congestive heart failure following formation of pseudocysts (clusters of amastigotes in heart tissue)
-parasite-induced heart disease is a leading cause of death in Latin America
-diagnosis: mature flagellated trypanosomes in blood/lymph
-treatment: benzinidazole or nifurtimox
-causes African sleeping sickness
-the insect vector is the tsetse fly
-humans usually infected when bitten by infected tsetse flies
-fever, lymph node swelling, and headaches
-meningoencephalitis
-endemic in parts of the tropics and subtropics (Central and South America)
-wild and domestic dogs and small rodents are common hosts
---zoonosis, transmitted by sandfly
-has two developmental stages
amastigotes (lack flagella) • multiply in host’s macrophages and monocytes
promastigotes (flagellated) • develop extracellularly within a vector’s gut
-three clinical forms often observed:
cutaneous condition: large painless sores on head and face region
mucocutaneous condition • single or multiple lesions at mucosal sites of infection • can cause respiratory problems
visceral condition (kala-azar): fatal
-most cases heal without treatment
-diagnosis by identification of amastigotes in samples from cutaneous lesions, spleen, bone marrow
-prevention limited to reducing exposure to reservoir and vector
-common gastrointestinal disease in the United States
-ingest cysts in contaminated water or when swimming
-life cycle similar to that of Entamoeba
-trophozoites multiply in the small intestines (resemble a face)
-foul smelling stools (“rotten egg” smell)
-diagnosis: oval cysts in stool, xTAG GPP test for the presence of its DNA
-treatment: Metronidazole drug of choice
-prevent infections in endemic areas by use of filtered water -causes beaver fever
-lives in the genitourinary system of men and women
-transmitted almost exclusively via sex
-occurs in people with preexisting STD or multiple sex partners
-infection of women results in vaginosis
-diagnosis by microscopic observation of actively motile trophozoites in vaginal and urethral secretions
-trophozoites are flat, possess five flagella and a sail-like undulating membrane -diagnosis: immunoassay -treatment: metronidazol
-causative agent of malaria: endemic throughout the tropics and subtropics -four species cause malaria -mosquitoes of genus Anopheles are vectors -life cycle has three prominent stages
exoerythrocytic stage (liver phase in humans)
erythrocytic cycle (within RBCs in humans)
sporogonic phase (in mosquitoes)
-diagnosis: characteristic ring like trophozoites within erythrocytes
-symptoms of malaria associated with cycles of erythrocyte lysis
• fever, chills, anemia, weakness and fatigue
-can cause blackwater fever
• high fever, erythrocyte lysis, renal failure, and dark urine
-cerebral malaria results in tissue death in the brain
-diagnosis: ring-like trophozoites within erythrocytes
-treatment: Chloroquine, mefloquine or atovaquone with proguanil
-prevent malaria by limiting contact with mosquitoes
-wild and domestic mammals and birds are major reservoir
-cats are the definitive host
-infection due to consumption of undercooked meat containing the parasite
-ingestion or inhalation of contaminated soil can also occur
-can cross the placenta and infect the fetus
-transplacental transfer can result in still births, abortions, mental retardation, blindness, jaundice, etc.
-more severe in AIDS patients
-treatment: clindamycin