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What is an emerging disease
a disease that has appeared in a population for the first time, or that may have existed previously but is rapidly increasing in incidence or geographic range.
what is a re-emerging or resurging disease
have been around for decades or centuries but have come back in a different form, different intensity or a different location.
Neglected tropical diseases have high prevalence among which population
the rural poor; 1 billion people
what type of diseases hit in high prevalence in the rural poor
non emerging, ancient diseases. As well as chronic diseases that cause disability or disfigurement
How prevalent are the diseases in the rural poor
high disease burden, but low mortality. 530,000
which are the two arboviruses
hemorrhagic, and encephalitic viruses.
how many animals viruses are suspected to be transmitted by arthropods
501
how many arthropod transmited animal viruses have been documented to cause illness in humans
134
with the exception of what two diseases are humans always the dead-end hosts
Dengue and Yellow Fever
To which family does the dengue virus belong to
flaviviradae
to what genus does dengue belong to
flavivirus
how many viruses does the family Flaviviridae include
70
of the 70 flaviviridae viruses, how many are mosquito borne
40
Besides dengue, what are other known flaviviruses
West Nile, Japanese Encephalitis, and Yellow fever.
how does serotype immunity work in dengue
infection with one serotype produces immunity for remainder of life against that serotype; very limited cross-immunity: around 2 months to a year
do all four dengue serotypes produce the same disease?
yes
What is the WHO definition of dengue hemorrhagic fever (1975)
Fever (bladder problems, constant headaches, severe dizziness and loss of appetite), Hemorrhagic tendency, low platelet count, Evidence of plasma leakage.
which mosquito species transmits dengue
Aedes aegypti
how long is the incubation of aedes aegypti
3-14 days
how long is the febrile period of aedes aegypti
5-7 days
how long is covalescence in aedes aegypti
3 weeks
what percent of dengue patients are asymptomatic
50 percent
what is the most common manifestation of dengue
undifferentiated fever
what are the symptoms of classic dengue fever
fever, headache, muscle, and joint pain, nausea/ vomiting, rash.
What are the symptoms of dengue shock syndrome (DSS)
dangerously low blood pressure, patient goes into shock, death.
what are some characteristics of aedes aegypti
well adapted to contemporary urban life; tires, containers, cans, flowerpots, tree holes; nervous feeders, multiple hosts
what is the primary preferred habitat of aedes aegypti adults
homes where they can feed on human blood
when and how was there an attempt to control Aedes aegypti
In the Americas, 1970's with DDT
Aedes albopictus transmits what 5 diseases
dengue, yellow fever, eastern equine encephalitis, La Crosse virus, and West Nile virus.
why is Aedes albopictus a preferred vector to Aedes aegypti
it is a less efficient vector of dengue
why is Aedes albopictus a less effective vector for dengue
it is a more generalist feeder
What is the transmission cycle of dengue
dengue came from the forrest but is currently maintained in human populations; may still exist in jungled but plays no role in epidemics
what vectors Yellow Fever
aedes aegypti
where did yellow fever originate
africa
when did yellow fever spread to the New World
during the 14th adn 15th centuries via slave trade; though the freezing killed them , the migrating slaves reintroduced it
how long is the intrinsic incubation period of yellow fever
3-6 days
what is the inapparent/ apparent ration in children for yellow fever
1/2
what is the inapparent/ apparent ratio in adults for yellow fever
1/22
what are the mild yellow fever symtoms
fever, nausea, headache, slow heart rate. Nose bleeding in particular.
what are some of the toxic phase symptoms for yellow fever
liver damage with Jaundice, Internal bleeding with black vomit, seizures, bloody nose and gums, red eyes.
What is the Sylvatic cycle
mosquitoes to primates to mosquitoes in jungle
what is the rural cycle
primates to mosquitoes to humans in the rural tropics
what is the urban cycle
rural tropics, to suburban, to urban. Humans carry between cities, not mosquitoes.
What cycle is yellow fever maintained in, or resivoired
zylvatic cycle; by primates
who brings yellow fever from the sylvatic to urban and rural cycles
people entering the jungle
where does the rural cycle tak eplace
edge of forrest where more than just one species of mosquitoes is involved
what species is primairly responsible for transmission in urban cycles
aedes aegypti
how is the american yellow fever cycle different than the african one
there is no intermediate rural cycle, only sylvatic and urban. Humans take it between the two
what percent of west nile is asymptomatic
80 percent
how many of the 20 percent symptomatic west nile patients develop severe symtpoms
1/50
what are the three types of west nile
west nile encephalitis, west nile mninghitis, and west nile meningoencephalitis
what is a bridge vector
a vector repsonsible for transmitting disease from animals to humans; a generalist feeder
what three species get west nile
birds, humans, and horses; mosquitoe is the bridge vector
what mosquitoes transmits west nile
62 species; culex pipens (northern house mosquitoe) and culex quinquefasciatus (southern house mosquitoe) are the most ocmmon. (also c.salinarius, c. restauns, and c tarsalis)
Where does eastern equine encephalitis happen
easter usa in swampy regions; rural agricultural areas
what is the inapparent to apparent ration of eee
low; high proportion of infected horses and people become ill, but only 4-5 percent develope eee.
whate are the symptoms of eee
fever; chills, malais, myalgia arthralgia (muscle and joint pain)
what is the fatality rate for acute necrotizing encephalitis
33 percent
where is acute necrotizing encephalitis prevalent
children under 15 or adults over 50
what are the causes of death of acute necrotizing encephalitis
coma, death, stupor, convulsions, and myocarditis along with lung failure
what species vectors eeev
Aedes taeniorhyctus (and Ae. solicitans)
what is the resivoir for eee
birds
what are the dead end hosts for eee
game birds, horses, humans
Where is weev found
western, rural human populations
what is the inapparent/apparent ration for weev
high, mostly asymptomatic
symptoms for weev
mild; headache and fever
percent of weev patients that get severe encephalitis
13 percent
symptoms of weev severe encehpalitis
fever, drowsiness, nausea, confusion, coma, seizures
what percent of weev is fatal
3 percent of the 13 percent with severe sypmtoms
what populations does weev kill and is there treatment
children and elderly, only supportive treatment, no cure.
slev was first recognized in what year
1933 in snt lous
what family of viruses is slev
flaviviridae
how many reported cases and deaths of slev were in st louis
1095 cases, and 201 deaths
where is slev found
southern canada to argentina (america)
how many slev cases have been reported since 64
4651
what is the resivoir host for slev
birds
what are the vectors for slev
culex nigripalpus in california. culex tarsalis in midwest, culex pipiens everywhere else
lacev is transmited by what mosquitoe species
aedes triseriatus
where does lacev occure
wooded areas where resivoir hosts are found: rodents, chipmunks, squirrles
what are lacev's resivoirs
rodents, chipmunks, squirrels
what are lacev's symptoms
mild: fever; severe: coma, death (encephalitis)
who is mostly affected by lacev
children under 16
what percent of lacev is fatal
less than one percent of severe cases
what family of viruses is lacev
bunyaviridae
how many neuroinvasive cases of lacev occure each year
80-100
jev is vectored by what
culex species
where is jev reservoired
swine and wild birds
when was the major epidemic of jev; how many cases
1924 in japan, 6125 cases, half the fatalitites
how many current cases of jev
30-50k
what are jev's symptoms
Mild: fever and headache; acute: paralisis, seizures, coma, death
who does jev affect
children under 15
mortality rate of jev
30 percent of acute cases
is there treatment for jev
yes, a vaccine
what family of viruses is jev
flaviriridae
what superfamily are filarial worms in
filariodea
what family are filarial worms in
onchocericidae
how many genre of filarial worms
34
which 4 filarial worms are of medical importance to humans
wuchereia, brugia, onchocerca, and loa
what causes lyphatic filiariasis
wuchereri bancrofti, brugia malayi, and brugia timori
what percent of cases of lymphatic filiariris are caused by brugia
9 percent
what vectors wucherei bancrofti
culex, aedes anopheles; primairly culex quinquefaciatus
wucheria bancrofti life cycle
bite>lymphatic system>blood and lymph>mosquitoe>larva develop in mosqutioe>bite again (larvae enter, microphilaria leave)
Lymphatic filariasis phase 1 involves what
no symtoms, microfilaria in blood, people are resivoir
lyphatic filiariasis pahse 2 involves what
acute inflamatory lymphatic disease (adenolymphangitis); secondary bacterial infections, no microfilaria
Lymphatic filariasis phase 3 involves what
blockage of lymph channels; Chyluria (lymph in urine) Lymphoedema (big feet); hydrocoel (big balls)
what blocks channes in elephantitis (LF)
adult worms carcases
is elephantitis fatal
no
what causes river blindness
ochocera volvulus
onchocera volvulus life cycle
larva enter (fly bite)>subcutaneous>nodule forms>re-emerge on skin>leave as microfilaria to flies> larval cycles> back in host through bite
what vectors ochocera volvulus (river blindness)
family simuliidae, blackflie
which species of black fly is of most importance for river blindness
simulium damnosum (95 percent of transmission )
what do simuliidae larva feed on
organid debree in flowing water
where do simuliddae live
flowing water, sedentary in sumberged rocks and crabs
What is the first stage of river blindness
nodules (below waist in africa, above waist in america), caused by L3 larvae
how long do onchoceriasis worms need to mature in skin
1 year
how long can onchoceriais worms live
up to 15 years
What is the second stage of river blindess
microfilaria cause elastic fiber scaring, loss of pigmentation, itching, sleeplessnes.
what are some results of onchoceriasis secondary symtoms
social outcast, suicide, lizard skin, leopard skin
Tertiary river blindess symptoms
microfilariae reach the eyes, they damage the eye when they die in it; irreversable
how many people suvver onchoceriasis blindness
240k people
where is river blindness found in
older than 40, some adolescents
Onchocera volvulus i west african savana
common blindness
onchocera volvulus in west africa forest
rare blindness
onchocera voluvulus in east africa
skin problems, rare blindness
are different strains of ochocera found in savana vs forrest
yes
why don't bednets and irs work on simmullidae control
adults are daytime feeders
what works best against sumullidae for control
repellents; incectisiding rivers
how many km of river were treated between 1986 and 1991
50km
how is river blindness treated
Ivermectin (mectizan) (DEC too dangerous)
what does Ivermectin (mectizan) do
prevents adult females from producing microfialriae in one dose with few side effects
what are the 2 medically important genre of trypanosomatidae
trypanosoma and leismania
what type of organisms are trypanosomatidae
protozoans
what is african trypanosomiasis
sleeping sickness
what is amercian trypanosomiases
chagas disease
what vectors trypanosoma
tsetse fly (africa) kissing bug (america)
what vectors leishmania
sandflies
trypanosoma brucei life cycle
epimastigote>trypomastigone (in vector)> infects humans>lymph chanels and blood> trypomastigote>vector>epimastigoe
uniqueness of tryanosoma bruci
cyclodeveopmental in humans; develomental in vectors
where are epimastigotes of trypanosoma found
in vector
where do trypomastigotes develop comletely
humans
what are the 3 subspecies of trypanosoma brucei
T. brucei brucei (animals) T. brucei gambinse (wet africa, chronic sleeping sickness), and T. brucei rhodesiense (east africa, acute sleeping sickness)
where is acute sleeping sickness found and what causes it
East africa, T. brucei rhodesinse
Where is chronic sleeping sickness found and what causes it
West africa, T. brucei gambinse
stage 1 chronic trypanosomiasis
west africa, 5-15 days after bite, lesion forms
stage 2 chronic trypanomiasis
1-3 weeks after bite; periodic fever, fatigue, joint pain; lasts 3 months. Can Cause Organ Damage
what is winterbom's sign
lesions caused by trypanosomiasis (chronic)
stage 3 chronic tripanosomiasis
meningoencephalitic stage; takes several years to happen; agresivness, fatigue, coma, death.
Acute trypanosomiasis
caused by t. brucei rhodesinse; death in less than 12 months, not years.
west vs east HAT
forrest vs savana; gambiense vs rhodenise; chronic vs acute; slow vs fast death.
tsetse fly family and genus
glossinidae; glossina
where are tse tse found
south saharan africa
2 glossina species
g. mortistans, g. Palpalis
glossina mortisans found in
east africa woodland savanna, feeds on cattle
glossina palpalis found in
west africa rivers and forrest; feeds on humans
how do tsetse flies reproduce
single, 3rd instar larvae at a time; 8-10 days development.
glosina control
disease screeenings, killing wildlife and insectiside (east africa), TRAPS, sterilized insects (zanzibar)
where were steralized tsetse released
zanszibar
where were kiling of wildlife used to control tsetse flie
east afric
what causes chagas disease
trypanosoma cruzi
what is T cruzi's life cycle
epimastigote to trypomastigote in vector; trypomastigote to amastigote in humans
what is the vector development of T cruzi
picks up trypomastigote> epimastiote> trypomastigote again>back in human
what is human development of T cruzi
trypomastigote to amastigote back to trypomastigote and into vector
where do amastigotes develop
inside the muscle and nurao cells; they distroy them
unique about T cruzi cycle
cyclodevelopmental in humans
where is T cruzi found
latin american coasts
Acute T chagas symptoms
ring of romania (eye), mostly in children; fever, vomit, and diarhea; heart tissue scarring, 80 percent o fcardiac nerves lost
how long before acute T chagas kills
3-4 weeks in 5 percent of cases
Chronic T chagas symptoms
30 percent of acute survivors; after years of asymptomatic enfection (10-30 years); cns and pns; nerves contoling esophagus and colon destroyed: megacolon, megaesohpagus; death from crhonic heart failure
what vectors t cruzi
heteroptera>reduvvidae>triatominae
what are the two highly domesticated species of triatominae
triatoma infestans; trhodinus prolixus
Triatomidae resivoirs
opossums, rats, squirrels, skinks, iguanas, bats, birds
infestans and R. prolixus resivoirs
domestic: donkeys, cattle, horses, etc.DOGS and HUMANS
Triatomidae control
IRS, House plastering, bloodbank screening, prenatal screening
1991 southern cone initiative
chile argentina, boivia, brazil, paraguay, uruguay
number of infected army recruites
1.9, down from 10 percent in 65

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