Parasites + vector-borne diseases

Question 1

Define parasites

Answer 1

reliant on other living organisms (hosts) for part or all of their nutritional requirements

Question 2

Define pathogens

Answer 2

organisms that causes disease

Question 3

Define vector

Answer 3

organisms that do not cause disease themselves but which transmit infection by conveying pathogens from one host to another

Question 4

Define intermediate host

Answer 4

an organism inside which a parasite does not sexually reproduce

Question 5

Define definitive host

Answer 5

the host in which the parasite reproduces sexually

Question 6

Define zoonotic diseases

Answer 6

infects humans and animals

Question 7

Define anthroponotic diseases

Answer 7

pass only from human to human

Question 8

Define reservoir

Answer 8

long-term hosts of a parasite they are normally unharmed by it
they serve as a source of infection to people
can be targeted for prevention and control

Question 9

Name some medically important reservoirs

Answer 9

Field mice for hantaviruses and Lassa fever
Raccoons, skunks, foxes and bats for rabies
Shellfish for cholera

Question 10

Factors influencing spread of disease

Answer 10

socioeconomic conditions - migrations
wars and refugee movements
modes of human behaviour
intercontinental travel
problems with public health services
globalisation of food supplies
microbial adaptation and resistance
global warming

Question 11

What impact do vector-borne diseases have?

Answer 11

human health: morbidity, disability and mortality
economic burden and poverty
animal health: production losses and companion animal welfare

Question 12

What factors affect vector-borne diseases?

Answer 12

habitat changes
war and civil unrest
HIV and immunosuppression
atmospheric and climate changes
natural vector movement by wind and birds
drug and insecticide resistance
pollution
increased trade and travel
global and local management failure

Question 13

Which insects carry disease?

Answer 13

fleas - plague
mosquitos - malaria, dengue, yellow fever, filariasis, west nile virus
ticks - lyme disease, tick-borne viruses
lice - trench fever
tsetse - african trypanosomiasis
sandfly - leishmaniasis
blackfly - oncocerciasis

Question 14

How did malaria disappear in the UK without vector control or climate change?

Answer 14

increased drainage of marshes
increased livestock density
reduced human density

Question 15

Causes of re-emergence of malaria in Africa

Answer 15

frequent armed conflicts and civil unrest - large populations forced to settle in areas of high malaria transmission

adverse socioeconomic conditions - reduced health budget

migration to areas of country with high transmission

high birth rates - increase in susceptible population

rapid spread of resistance of malaria parasites to chloroquine and other quinolones

DDT resistant anopheles

changing rainfall patterns and water development projects

agricultural development - rice paddies

Question 16

What is onchocerciasis?

Answer 16

progressive inflammatory eye and skin disease
river blindness
caused by infection with filarial nematode Onchocerca volvulus

visual impairment due to progressive scarring of the cornea and to a lesser extent the retina and optic nerve

Question 17

Approaches to control vector-borne diseases

Answer 17

economic development
civil stability and public works
insecticide spraying
biological control
sterile insect technique
paratransgenics
transgenics
RIDL (release of insect dominant lethal)
refractory insects with selective advantage
vaccines
drugs