zoonotic & vector borne disease
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the term refers to an.... that is...
the term zoonosis refers to an infection or infectious disease transmissible under natural conditions
from vertebrate animals to humans
- -zooanthroponosis - humans to animals ---these situations are less commonly talked about
- - anthropozonosis-- animals to humans *2nd most common
transmission models of zoonosis (4)
2. b or s
3. i or i
4. b of an...
- a contact with the skin
- a bite or scratch from an animal
- direct inhalattion or ingestion
- the bite of an arthropod vector
-in other fields....
- an insect or any living carrier that transports an infectious agent from an infected individual or its wastes to a susceptible individual or its food or immediate surroundings.
- (has specific genes in the virus, the virus can infect--and delivers products in to the genomes of the host---vectors in a different field may have different meanings.
examples of vectors (who are just part of the chain in transmission of infectious disease agents)
they transmit from ___ to _____
- various species of rodents (rats and mice)
- anthropods (mosquitos, ticks, ands flies, biting midges)--they transmit from animals to humans
4 major possibilities for the spread of vector borne diseases in the US
- 1. humanities encroachment
- 2. easy travel workldwide
- 3. illegal importation of animals---reservoirs
- 4. new immigrants from endemic areas
Vector Borne Diseases ( 5)
- Leishmaniasis (sand fly vector)
- Lyme Disease
- Rocky Mountain Spotted Fever
found in over...
more than __% at risk
endemic regions incliude...
annual death toll is
- disease found in more than 100 countries with more than 40% of the worlds population at risk
- edemic regions include Central and South America, Afirca, India, and Southeast Asia, the Middle East, and OCeania.
Annual death toll from Malaria is near 1 million persons.
Infectious agents of Malaria
- plasmodium vivax
- plasmodium falciparum (most deadly)
- plasmodium malariae
- plasmodium ovalae
the direct cost of malaria are ___ BILLION annually
- global direct economic costs incurred by malaria are estimated to be 12 billion US annually
- -the direct costs include those for treatments and prevention of the disease (e.g. medicine , hospitalization, and pesticide use)
- *lost productivity
slide onthe the life cycle of the parasite of the genus Plasmodium
malaria--- the obligated passages, intracellular passages-- mosiquotes are carriers can pass to humans in the blood vessles---there are 2 stages--infecitous stages and diagnosis stages ---> i
What can be done to control malaria
during the mid 20th...
during the mid-20th century, malaria was all elminated and in many couintries due to the use of pesticides, particularly DDT, (dichloro-diphenyl trichloroethene)
thought to be harmuful to wildlife, outdoor sparying of DDT was discontinued in many developed countries
some coutries now permit spraying of DDT inside homes
- CDC guidelines for clinicians
- common drugs in use:
- 1. chloroquine
- 2. atovaquone-proguanil (malarone)
- 3. mefloquine (Lariam)
- 4. Quinine
- 5. doxycyline
- 6. clindamycin
cutaneous lesihmaniasis is caused by intracellurlar protozoa of the genus Leishmania
- caustative agents
- domain: eukaryota
- phylum: eugenlenzoa
- class: kinetoplastida
- order: trypanosomatida
- species > 30
-transmitted from reservior human host
- the reserviour for the cutaneous form of lesihmanaisis consists of various rodents (human beings, carnivores, and wild rodents.
- the disease is transmitted from the reserviour to the human host by a sand fly know was the phlebotomus fly
the natural ... is really the rodent in the environment
- ◆ Endemic in a total of 88 countries with 2
- million new cases each year.
- ◆ Most of the affected countries are in the tropics and subtropics.
- ◆ The settings of leishmaniasis range
- from rain forests in Central and South America to deserts in West Asia.
- 500,000 new visceral case/yr mainly in India, Bangladesh, Nepal, Sudan, and Brazil (>90%)
- mostly (more than 1/2 in india)
increases in in leishmaniasis (4)
1. movt of...
4. and ___ change due to...
- 1. movement of the human population into endemic areas
- 2. increasing urbanization
- 3. extension of agricultutal projects into edemic areas
- 4. climate change due to global warming
leishmaniasis treatment -cdc guidelines
3. pentavalent ant.. compound
- CDC guidleine for Clinicain
- Drug considerations
- 1. amphotericin
- 2. miltefosin
- 3. pentavalent antimony compounds
symptoms fevers skin rashes etc.
1. infectious agent
2. condition infect both...
3. transmitted by.. that is haborded
4. historians the
- 1. Yersinia Pestis is the infetious agent for plaque
- 2. a condition that infects both animals and humans
- 3. transmitted by the bite of a flea harbored by rodents
- historians believe that the plague epidemic during the middle ages (the black death) was caused by fleas from infested rats
the black death
2. frist struck in europe
3. killed at least...
- 1. also known that the black plague was a devastating pandemic that first struck Europe in the mid to late 2. 14th century (1347-1351)
- 3. killing between 1/3 and 2/3 of europes population
- almost simuilaneous epidemics occurs accross large portions of Asia and the Middle East during the same period, indicating that the European outbreak was actually part of a multi-regional pandemic
- including the Middle eastern lands, india and china, the Black Death killed at least 75 million people
Bubonic Plague versus Plague ...
- cannot see this side--- look up the difference later
- from book:L
- bubonic plaguq- non specific symptoms, fevers, chills, headache, and them progress into infected lypmh nodes) at the site of the initial flea bite, there may be secondary involvment of the lungs known as the pneumonic plague
- the epidemiologic significance of the this form of the plaque is that respiratory droplets from and infected person can tranfer Y. pestis to other individuals and the case fatality rate for untreated bubonic plaqwue is high ranging from 50-60%. patients who are infected with the disease need to be placed in strict isolation and thier clothing and other personal items should be disinfected.
- persons who had contact with the patient need to be under quanrtine.
WHO estimate world wide infections
- WHO estimates 2000-3000 infections are world-wide each year
- Only 1-15 cases in the Western part of the US
- South America: brazil, bolivia, and Peru
- South Africa- Namibia, Angola, Mauritania
- Asia: China, India, Mongonia, Kazakhstan
in the US
numbers have increased in the 80s but there hasnt been more than 15 cases ever.
Plague as a biological weapon...
3. readily available .
4. fatality rate...
- 1. widespread avavilability of Y. pestis in microbe banks around the worlkd
- 2widespread natual avialabiity of the Y pestis bacteria in endemic areas (like in reservoirs)
- readily available technique for mass production of Y pestis
- the fatality rate of the pneumoic plaque is untreated cases is extremely high
- plaque has the potential for secondary spread from person to person following an attack
- Y pestis can be disseminated in aersol form
- plaque has a low infectious dose
- antibiotic resistant strains exist in nature
- treatment: streptomycine, gentamicin
- Prevention: eliminate urban plaque with sanitation
- -vaccine: not effective & severe inflammatory reactions
- a condition identified in 1970 when a cluster of artritis cases occurred among chidlren around the area of Lyme, CT
- the casuative agent for the disease is a spirochete bacterium known was
- Borrelia burgdorferi
- When infected deer ticks bite human beings the disease may be transmitted
- bulls eye mark on the skin
- reported worldwide and through the united stats
- diffferent types of ticks are the carriers in difference regions
- not all ticks are infected (2-90%)
vectors of lyme disease
how do deer ticks become infected with LD
??? do this
incidence and distribution of Lyme disease in the USA
- in the east and in the west coasts in the middle ther eare none
- it is abundandt in the northeast
reported cases of lyme disease inthe usa
this is more serious in the USA than the -plaque, the cases have been consistent over the years.
month onset of Lyme
- in the warmer months people go outside more
- also more easily stay alive and is transmitted from animal to animal
LYme disease control
- treatments: doxycycline, amoxicillin, penicillin, ceftriaxone (IV)
- prevention: avoid tick infected areas
- wear light colored clothes, wear hat and long-sleeved shirts, walk in the center of the road.
Rocky Mounttain Spotted Fever
- tick borne disease
- causal agent: Rickettsia Rickettsii, a rickettsial agent (
- transmitted to human by the bite of infected tick species
rickettsia rickettsii and induced hemorrhagic rash
Vectors: american dog ticks and rocky mountain wood ticks
- abdominal pain (may mimic appendicititis or other causes of acute abdominal pain)
- muscle pain
- lack of appetitte
Rocky mountain spotted fever
- initially reported in 1986 as "black measles" and reported in 1930s from toher parts of the US
- the most severe and more frequently reported rickettsial illness in the US
- diagnoses throughout the Americas
- About 500-600 cases per year in the US (mostly in children)
- Case fatality rate up to 25% among untreated patients.
- agent: similar to viruses in that they reporduce within the living cells and are similar to some bacteria in that they require oxygen and are susceptible to antibiotics
- frebile disease with sudden onset of moderate to high fevers with may last up to 3 weeks when untreated
- case fatality rate is 25% among untreated but drops dramatically when patients are treated with antibiotics early in the course of the disease
number fo annual cases of RMSF
- not a very large number of people..
- antibiotic treatment increased case fatality rate
- the number of cases has not been consistent over the years but overall the incidence is low
- environmental conditions change the %
Control of RMSF
- treatment with antibiotics (deoxycycline)prevention to avoid areas
- no vaccine is currently available
Arthropod Borne Viral Disease
- Also known as arboviral disease
- a group of viral disease that are most frequenlt acquired when blood feeding arthopod vectors infect a human host
- vectors that transmit areboviruses include ticks, sand flies, bitting midges and mosquitos.
there are 3 categories
- alphaviruses ( Eastern Equine, encephalitis, Western Equine encephalitis Venezuelan equine encephalitis
- flavivirses (St. Louis encephalitis Japanese encephalitis Yellow fever, West Nile virus, Dengue
- (more info on slide)
- different from bacteria--only one type of nuclea acid (RNA)
- the genome is one piece with 10,000-12,000 nuceotides
- the virus is envloped and forms speherical particles (65-70nm in diameter) very small
- Alphavirus: st lous encephalitis virus, eastern euquine encephalitiis curs finish from slide....
finish from slide
- transmission occurs via an arthropod vector (mosquitos, tick, or sandfly
- exception: Hantaviruses are transmitted through contact with deer mice feces. Incidence of infection is
- closely linked to vector activity, for example, mosquito-borne
- viruses are more common in the
- viruses are very different
- not bacteria
obligative intracellur parasite-and very different from other organisisms because the genome has either have RNA and DNA never both!
- belong to the phylum : Arthopoda
- insects: the largest class of arthrpods
Four main clinical symptoms of arboviral disease
2. acute but benign... of...w/or w/o...
- 1. actute central nerovus system illness
- 2. acture benign fevers of short duration with and without an exanthum (rash)
- 3. hemorrhagic fevers
- 4. polyarthritis and rash with or without fever of variable duration
Arthropod-Borne viral hemorrhagic fever (VHF)
- viruses that cause VHF require an animal host or insect host (arthorpod vector) as a natural reservoir
- examples of animal host reservioirs include rodents such as the cotton rat, deer, mouse and house mouse.
- the virsues are limtied to those geograpahic arras in which the host species reside
Examples of viral hemorrhagic fever viruses
acute inflamation of: (3)
etiologic agents are virusese associated with encephalitis
e.g. St lousi encephalistis, western equine encephic
- causes by a virus that produces an acute inflammation of
- 1. sections of the brain.
- 2. spinal cord
- 3. meninges
1. transmitted by the bite of..
2. reservois for some forms consist of...
3. cost the arboroviruses...
- transmitted by the bite of mosquitoes from the reservois to a human host
- the reservoir for some forms of encephaitis viruses consists of nonhuman vertebrate host
- cost of arborovirsise is approxmitily $150 million per year including vector control and surveillance activities.
west nile virus
2. etilogic agent: flavirus
3. mos (feed on infeceted...)
- classified as a mosquito-borne arboviral disease, the etilogic agent in Flavivrus
- mosquitos are the carriers that become infected when they feed on infected birds
human cases of WNV in the USA from 1990-2003
there is a dramtic increase each year
WNV spreading from eastern to western
starts in NY, spread south and west --to almost everywhere in the country.
refers to zoonotic disease that are caused by either apprarently new agents or by known agents that occur in locales or species that previously did not appear to be affected by these known agents
factors associated with the rise of emerging zoonoses
1. e c
2. h b
- 1. ecological changes that results from agricultural practices (e.g. deforestations, conversion of grasslands, and irrigation
- 2. other factors include changes in the human population and human behavior (e.g. wars, migrtation, and urbanization).
Examples of emerigin zoonoses and their contributing factors
- 1. hantaviruses- ecological/environmental changes and increasing rodent contacts
- 2. escherichia coli-O157:H7- (hemolytic uremic syndrome) mass food processing techonolgy and contamination of meat
Hantavirus Pulmonary syndrom (HPS)
- -the causative agent is hantavirus, part of the viral family known as Bunyaviridae
- -may be transmitted when aerosolized (airborne) urine and dropping from infected rodents are inhaled
- primary vectors are four species of rodents :cotton rat, rice rat, white-footed mouse and deer mouse
the main host (carrier) is the deer mouse
in the west and south west
Yosemite National Park
fatality rate? %
- claused by Flaviviruses
- the vector for the disease is Aedes aegypti mosquito
- occurs primarily in tropical areas of the worlth (southeast asiam, tropical africa, south america)
- the proportion of deaths cab be as high as 40-50% when the diseae is untreated.
Countries at risk of Denque
- >2.5 billion people at risk
- 50-100 million annual infections
- 500, 000 cases of severe dengue (hospitalized)
- 20, 000-25, 000 deaths
- **no legal vaccination!
Dengue Virus has 4 serotypes (different regions different times etc.
- vector: mosquitos
- clinical presentations: at the beginning--non smyptomatic, more symptoms
- dengue fever : (DF)
- dengue hemorrhagic fever (DHF)
- degnue shock syndrome (DSS)
Dengue Fever Map US 2010
- small number in 2010
- occurrence of denque fever in continential US has been documented
- Southern Texas and the Southeastern states are t theoretical risks for transmission of dengue and sporadic outbreaks
- the virus may be imported into the United States by travelers who are returning from endemic tropical areas.
Denque Fever in Hawaii
- 1st large-scale DF epidemic in the late 1840
- the 2nd outbreak at the turn-ofthe century 30,000 cases
- epidemic dengue on oahu in 1943 to 1944 1,498 infections
- Dengue virus serotypes 1 infections in Sept 2001--122 cases
Control of Mosquito borne diesease
- drain standing water
- sanitation--good solid waste management
- biological control- preadatotry fish and parasites
- repair window screens
- wear repellents and protective clothing
- chemical - insecticides and larvacides
1. by being one with the ground
4. put away ur food
- facilitates by understanding a fly's life cycle
- eliminating breeding media
- sanitation- good solid waste managment
- denying food sources as breeding areas
Flea Control (4)
- 1. treating animals
- 2. disinfecting building interiors
- 3. treating animal quarters
- 4. specific insecticides (depends on type of animals affected & indoors or outdoors).
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