midterm 2

vector control, hazmat general presentation,

how are diseases transmitted?

first a disease present in a reservoir (human, animal, environment), a vector (can become infected by the reservoir) can transmit the disease in or on its body,

what are disease vectors?

biological: an animal that is infected and spreads the infection to others (the pathogen reproduces in the host) it can transmit through bites (saliva…

mechanical: think of an animal that gets others sick and infected that does not get sick itself

A fly is carrying fecal matter and lands on food

a animal that carries a disease from host to host

vector

what are the types of hosts?

vector: mosquitoes

transmits: malaria, filariasis, Japanese encephalitis, dengue fever,

vector: lice

skin infections, epidemic typhus, relapsing fever

vector: fleas

plague, murine typhus

vector
: ticks

tick paralysis, tick-borne replasing fever

vector: rodents

rat bite fever, leptospirosis, salmonellosis

life cycle of a mosquito

1. egg

2. larva

3. pupa

4. adult

• it takes 10 days for it to get from egg to adult

• only female mosquitoes drink blood

• females mate once and then store the sperm in a special sack

anopheles

aedes

culex

anopheles: one egg at a time, the larvae are parallel, out late hours of the night 11pm-6am

aedes :deposit eggs in containers above water surface, larvae hang at angles and breathing tubes, hangs on clothing and is active during the day, swims in s motion

culex: deposits eggs on rafts on water, swims in jerky motions, are active during the evening

chart disease transmission

1. reservoir: Animal, environment, humans

   1. pathogen: bacteria, virus, microorganism, parasite

2. vector: living organism, arthropods for the most time, transmit to humans

   1. mechanical transformation

      1. susceptible host

   2. biological transformation

      1. definitive host

difference between direct and indirect transmission

• direct

  • direct contact, droplet spread

  • skin to skin, saliva, sexual intercourse

  • contact with soil or vegetation

  • sneezing, coughing, talking, droplets are let out to the air and are then inhaled by others

• indirect

  • air borne

    • infectious agents are carried by the wind

  • vehicles

    • food, water, biological products (blood), and fomites

  • vectors

    • mosquitoes, flies, ticks

anopheles (gambiae, funestus): is active during the hours 11pm and 6am. True or false?

True

Aedes (aegypti) deposits its eggs in what manner?

• deposits individual eggs inside containers just above water surface

• the larvae hang down at an angle, suspended by breathing tubes

culex (quinquefasciatus) swimming

larva swim in jerky motions

non biting flies transfer pathogens when they stick to their legs or body. true or false?

true

the life cycle of a fly is ____?

6 days to 6 weeks

how many eggs can a female fly lay in one month?

around 2,000 eggs

what is the life span of non biting flies

2-3 weeks during warmer climate

3 months in colder climates

what are the types of biting flies?

1. tsetse fly

2. sandfly

3. blackflies

the infected tsetse fly bites a person and infects them with Trypanosoma brucei which then causes…

African sleeping sickness

sandflies bite and infect a person which causes an infectious disease ____

leishmaniasis

the _______ is a vector for river blindness

black fly

river blindness causes what symptoms

all of the above

what kind of treatment is given to treat river blindness

ivermectin and doxycyline

types of rodent species biggest to smallest

1. norway rat (brown and sewer rat)

   1. rattus norvegicus

2. roof rat

   1. rattus rattus

3. house mouse

   1. mus musculus

4. multi-mammate rat

   1. mastomys natalenisis

what are some examples of vector borne diseases

1. african sleeping sickness

2. river blindness

3. filariasis

4. typhus

   1. murine

   2. epidemic

5. leptospirosis

6. scabies

7. yellow fever

8. tick borne relapsing fever

what is the causative agent for filarisis

wuchereria bancrofti filarial nematode

epidemic and murine typus are…

• epidemic

  • vector: lice

  • pathogen: rickettsia prowazekii

  • used as a bioterrorism weapon

• murine

  • vector: flea

  • pathogen: rickettsia typhi

  • reservoir: rats and mice

leptospirosis

pathogen: spirochete

vector: urine of rats and mice

at risk population: sailors, miners, sewer workers

scrub typhus

• vector: mites

• pathogen: rickettsia tsutsungamushi

• headache fever profuse sweating

scabies

vector: mites

mites burrows under skin and lays eggs

produces papules and vesicles at finger webs

yellow fever is caused by what pathogen?

flaviviruses

what is the vector of yellow fever?

ades agyepti mosquito

what symptoms does yellow fever cause?

fever, chills, nausea, loss of appetite

severe symptoms: jaundice, liver disease, kidney diseases

Yellow fever has a vaccine

true

tularemia symptoms:

fever lethargy, loss of appetite, lymph node swelling

what reservoirs does tularemia have?

rabbits, hares, beavers

what pathogen is responsible for tularemia?

fransicella tularensis

vectors for tularemia

dog tick and lone star tick

control strategies for vector control

3 types of strategies are environmental, mechanical, biological, chemical control

environmental control:

draining a standstill pond, disposal of garbage, person hygine

mechanical control

screen, traps, food covers, lids

biological control

fish that eat mosquito larvae, bateri producing toxin for killing larvae, fern floating to obstruct breeding

chemical control

repellants insecticides, larvicide, adulticide

vector: lice

control measure: mass laundering in hot water, mass delousing with insecticide

vector: mites

control measures: mass laundering, supply adequate water for washing and distribute soap to community

vector: ticks

control measures: clearing vegetation

vector: bedbugs

control measure: household and personal hygiene, insecticide spraying

vector: black flies

control measure: larviciding breeding sites in surrounding rivers

vector: cockroaches

control measures: protect food, insecticide powder or spraying

vector: snails

control measures: sanitation measures, drain or speed up water flow, spray molluscides

vector: rodents

• source reduction

  • clean shelter and surrounding

• prevent transmission

  • rat traps, rodenticide

• individual protection

  • make food stores rat proof

• poisons

  • anticoagulants: warfarin causes internal bleeding and death

  • rodenticides: zinc phosphate or arsenic oxide

vector: flies

• source reduction

  • refuse disposal, wastewater disposal, latrine covers

• prevent transmission

  • fly traps, space spraying

• individual protection

  • personal hygiene, insect screens

vector: fleas

• source reduction

  • clean shelter and surroundings

• prevent transmission

  • environmental sanitation and dusting

• individual protection

  • insecticide powdering of clothes and bedding, and rodent burrows and runaways

vector: mosquitoes

• source reduction

  • prevent breeding in field

• prevent transmission

  • wall spraying

• individual protection

  • nets, repellents

when dealing with fleas…

NEVER attack rodents before destroying fleas because the fleas will then attack and feed on humans after the rodents are gone

dusting of footpaths of rodents

when a rat cleans itself, the dust has already spread and killed the fleas

what is the definition of risk?

the degree at which the material can cause harm

perception of risk

evaluation of risk and the judgement of its consequences to the environment or their health

societal risk

individual risk

risk management

environmental risk assessment

risk assessment process

hazard identification

dose-response assessment

exposure assessment

risk characterization