The success of control measures against any disease is
- a knowledge of its aetiology (causative agent)
- natural history epidemiology, including its mode of
e.g. whether it is vector-borne, water-borne, or
transmitted by orofaecal, aerosol or venereal methods.
3. CONTROL OF PARASITIC DISEASES
Concepts of eradication, elimination, and control of
Environmental modification and cultural control
Role of government, foundations and aid organisations
4. CONCEPTS OF ERADICATION, ELIMINATION, AND CONTROL
OF PARASITIC DISEASES
Eradication indicates that the parasite no longer exists
anywhere in the world.
Therefore is no need to maintain treatment regimes or
By contrast, if a parasite is merely controlled, then it
continues to exist, though its incidence and prevalence,
morbidity and mortality in particular areas will reduced as
consequence of the ongoing control measures.
5. There are no example of successful parasite eradication
In many developed countries, may human parasites have
been eradicated as a consequence of the rise in living
standards, effective waste disposal, and improved
Improved meat hygiene inspection and concern over
zoonotic diseases have lead to the virtual elimination of
helmiths such as Enchinococcus granulosus and Taenia
6. Control of any disease by the reduction of parasite load or
vector population, thus reducing transmission, implies
recognition that there is likely to be a continuing problem
and hence commitment.
The objective is to reduce the disease to a level at which
it is acceptable to the community or the stockholder by
reducing morbidity to levels commensurate with
socioeconomic development or livestock productivity.
Parasitic infections tend to have their most severe impact
upon those who are poorly educated
But the risk of infection can often be reduced by simple
changes in behaviour
Education is a key feature of parasitic control
For example: if people understand that the large cysts
that grow inside them result from eating and drinking
substances that are contaminated with dog faeces, then
theoritically it should be relatively easy to reduce the
incidence of hydatid disease.
9. Educational materials leaflets, posters, radio and television
Avoid scientific terminology, employing illustrations and
Some example of country that has good success:
- So called „barefoot doctors‟
- Dispense simple treatment and verbal guidance to isolated
- Health messages often delivered via teachers
- Health clinics provide opportunity to talk to women in the
* Women – often have a strong influence on the behaviour of all
members in the family 9
10. 2) Finland
- During 1800s, hydatid disease was effectively controlled
for many years through the provision of educational
- Legislation and more effective treatments became
- By 1960s – the disease had been eliminated from the
11. Example of failure – Africa
- Insecticide-treated bed-nets
are effectively at preventing
malaria, provided that they use
- As a consequence, aid
agencies in parts of Africa
distribute free bed-nets and
instruct them how to use it.
- However the level of infant
mortality still remains high.
12. The bed-nets are not always appropriate for the way
people actually live.
Such as burden to hang and disassemble the net
The net traps heat difficult to sleep.
Risks – fire, safety of the children
They sleep outside of the house at night
13. ENVIRONMENTAL MODIFICATION AND CULTURAL CONTROL
Until the development of effective drugs and pesticides,
environmental modification and cultural control were the main
means of combating parasites, pests and diseases.
It was seldom understood why certain practices were effective
but experience taught us to do or not to certain things at
certain times of the year.
In countries with seasonal climates, the risk of infection is often
most pronounced at certain times of year and sometimes
possible to predict when or whether a parasite will be particular
problem and take appropriate action.
14. Relatively simple environmental modifications can reduce the
risk of exposure to many parasites diseases.
1)increasing the water flow rate in the irrigation channels and
removing plant growth
- unsuitable environment for the snails that acts as the
intermediate hosts of schistosomes
2) concrete farm yards and animal pens
- easy to keep clean of faeces
3) solid hut or house walls and ceiling
- Do not provide hiding places for the hemipteran bug vectors
of Trypanosoma cruzi
15. For ruminant parasitic species pasture and grazing
Grazing management has an important role in parasite control.
The aim of grazing management is to have vulnerable sheep
exposed to fewer larvae on pasture.
The result will be that fewer drenches will need to be used.
At the same time grazing management provides nutrition to
allow sheep to better deal with parasites.
16. Grazing paddocks alternately with sheep and cattle can
exploit the fact that most of the common worms of sheep
do not readily infect cattle, and vice-versa.
The best method for alternate grazing of sheep and cattle
is a 6-monthly interchange, with the sheep and cattle
being swapped in January and July.
- The timing and duration of cropping is ideal for preparing
paddocks that are virtually free of worm larvae.
- This is because most larvae are removed with the crop,
remaining larvae die because they are exposed to the
sun and there is no contamination with worm eggs since
the early autumn.
18. Preparation of 'Safe' Pastures.
- 'Safe' pastures are those with low numbers of infective
- Worm control can be greatly improved and drenching
frequency reduced by preparing 'safe' pastures for the
most susceptible animals in the flock.
20. BIOLOGICAL CONTROL
Biological control is an ecological method designed by
man for lower a pest or parasite population to keep these
populations at a non harmful level.
21. STEP 1. Accurate identification of the pest species and confirmation of the pest
as a target for biological control.
STEP 2. Surveys for natural enemies (generally insects, mites, nematodes and
diseases) are conducted in the area of origin of the pest
STEP 3. Determine host-specificity of potential control organisms to assess
impact on targets and nontargets and environmental safety.
STEP 4. Following approval from federal and state regulatory officials, biological
control agents are shipped to a domestic quarantine facility where they are
examined to confirm species identity and to determine whether they are free of
parasites and diseases.
STEP 5. These agents are tested in field plots to determine that the agents do
reduce densities of the target pest and do not have adverse effects on
nontargets. Once this small scale testing is completed, appropriate natural
enemies can be mass-reared to high numbers and released at field sites
established by county biologists.
STEP 6. Once released, each biological control agent is evaluated for
establishment, spread, impact on the target species, and impact on nontarget
species. Careful, long-term evaluation studies provide scientific data that are
used to improve current and future programs. Additional releases may be made in
an augmentative manner in systems where long-term stability of the natural 21
enemies is not feasible.
22. AGENTS FOR BIOLOGICAL CONTROL
These organisms include
- Biological control of insects may include predators (e.g. spider) parasites,
parasitoids, (insect parasites of insects)
- Some protozoa such as Haemogregarina, Nosema, Babesia and Theileria are
pathogenic for some parasites like "ticks"
3) Predacious nematode
- Steinernema (Neoaplectana) carpocapsae has shown some success against
mosquitoes on an experimental level.
- Some potential candidate has been identified by not much known about them.
- Bacillus thuringiensis are among the most widely used antagonists in biological
control of insects.
- After ingestion, target insects are killed by a gut toxin which is released from crystal
proteins in the bacterial spores 22
Fungi that exhibit anti-nematode properties have been
known for a long time.
They are divided into three major groups based on their
morphology and types of nematode-destroying
1. Predacious Fungi
2. Endo-parasitic Fungi
3. Egg-parasitic Fungi
24. PREDACIOUS FUNGI
Produce specialized nematode-trapping structures
(adhesive knobs, networks, rings etc.) on the mycelium
The trapping activity of the fungus was influenced by the
motility of the infective larvae & there is no specificity for
the parasitic species
E.g Arthobotrys spp. (A. oligospora)
- Cooperia oncophora
- H. contortus or Ostertagia circumcincta
26. (A) Formation of the fungal trap (white
arrow) after 6 h of the fungus/larva
(B) fungal trap in anastomosis (white
arrow), forming the scattered
adhesive three-dimensional network
trap and septate conidium of the D.
flagrans fungus (black arrow)
(C) scattered adhesive three-dimensional
network traps (white arrow)
(D) fungal hyphae of the control
without Ancylostoma spp. L3
(E) Ancylostoma spp. L3 in the control
(F) Ancylostoma spp. L3 captured, after
8 h of interaction with the fungus, at
the cephalic portion (white arrow) and
at the middle of the body (black
arrow) by traps in the anastomosis
process (dashed white arrow).
Maciel A. S., Araujo J. V., Campos A. K., Benjamin L. A., Freitas L. G., 2009. Scanning electron microscopy
of Ancylostoma spp. dog infective larvae captured and destroyed by the nematophagous fungus Duddingtonia
flagrans. Micron 40(4): 463 – 470.
27. ENDO-PARASITIC FUNGI
These invade nematodes either by penetration of cuticle from
sticky spores adhering to the cuticle or following ingestion of
spores which lodged in the gut.
Inside the host, they develop an infectious thallus which
absorbs the body contents.
Endoparasitic fungi have no extensive hyphal development
outside the body of the host except fertile hyphae such as
evacuation tubes or conidiophores that release the spores.
This type of fungi is obligate parasite of nematodes, with very
limited capacity to develop outside the prey and density
E.g Drechmeria coniospora
28. Shows conidia of fungus attached to
Diagram of Drechmeria showing buccal (mouth) region of the
salient features. nematode. Some spores have
germinated and you can see faintly the
sinuous hyphae of the parasite tracing
through the body of the victim.
Massive reproductive growth of 28
conidiophores and conidia Conidia attached to tail region of nematode.
of Drechmeria bursting through the
cuticle of the host.
29. EGG-PARASITIC FUNGI
These have the ability to attack the egg stage and may
have a role in the control of animal parasites which have
a long development and/or survival time in the egg stage
in the environment outside host
May be defined as fungal parasites of cyst and root-knot
The fungus was shown to be able to degrade the egg
shell enzymatically and infect the eggs
E.g Paecilomyces lilacinus
- Ascaridia galli and Parascaris equorum
- Toxocara canis 29
(A) Eggs of Ascaridia galli in Petri dishes of the
control group (white arrows).
(B) (B–D) Destroyed A. galli egg (white arrows)
after interaction with the hyphae and
chlamydospores of Pochonia
chlamydosporia fungus (black arrows)
F.R. Braga, J.V. Araújo, J.M. Araujo, L.N. Frassy, A.O. Tavela, F.E.F. Soares, R.O. Carvalho, L.M.
Queiroz and J.H. Queiroz. 2012. Pochonia chlamydosporia fungal activity in a solid medium and its
crude extract against eggs of Ascaridia galli. Journal of Helminthology 86(03): 348-352.
31. INTEGRATED PARASITE MANAGEMENT (IPM)
In livestock production
Goal is not to create parasite-free animals.
It is normal for sheep and goats to have parasites.
Goal is to prevent clinical disease and production losses
33. Good Management
Use of Clean or Safe Pastures
Pasture Rest and Rotation
34. GOOD MANAGEMENT
Internal parasite control starts with good management
and common sense.
Sheep should not be fed on the ground.
Feeders which cannot easily be contaminated with feces
should be utilized for grain, hay, and minerals.
Water should be clean and free from fecal matter.
Pastures and pens should not be overstocked.
When new sheep are acquired they should be isolated
from the rest of the flock for 30 days and aggressively
dewormed to prevent the introduction of drug-resistant
35. USE OF CLEAN OR SAFE PASTURES
Clean or safe pastures are pastures which are not
contaminated with the worm larvae that affect sheep.
Examples of clean pastures include:
- pastures that have not been grazed by sheep or goats for the
past 6 to 12 months;
- pastures which have been grazed by horses or cattle; pasture
fields in which a hay or silage crop has been removed;
- pasture fields which have been rotated with field crops; and
- pastures than have been recently established or renovated
While burning a pasture will remove worm larvae, there are no
pasture treatments that will effectively eliminate or reduce
36. PASTURE REST AND ROTATION
It is a common misconception that rotational grazing
helps to control internal parasites in sheep.
Intensive rotational grazing may actually contribute to
This is because rotating large groups of sheep and lambs
through small paddocks concentrates livestock and
infective parasite larvae onto the same small area.
37. Researchers in the Netherlands found that it takes three
months of rest for an infected pasture to return to a low level of
Researchers at Langston University (Oklahoma) determined
that a 65-day rest period was sufficient (for goats).
Rotational grazing is an effective management tool for
managing parasites, but only if pasture rest periods are long
enough (i.e. 60 days or more).
On the other hand, better nutrition provided by rotational
grazing may offset the effects of higher parasite loads on the
38. GRAZING STRATEGIES
Approximately 80 percent of the worm larvae can be
found in the first two inches of grass.
Therefore, sheep grazing taller forages will have fewer
Sheep should not be allowed to graze forages shorter
than 2 inches in height.
Sheep that browse also have fewer parasite problems.
Another grazing strategy is to wait until the dew has lifted
from the grass or grass has dried after a rain.
Dry conditions force parasites to stay at the base of the
plants where they are less likely to be consumed by the 38
39. MULTI-SPECIES GRAZING
Sheep (and goats) are generally not affected by the same
internal parasites as cattle and horses.
Consequently, pastures grazed by cattle and horses are
safe(r) for sheep (and goats) and conversely.
Sheep can be co-grazed with cattle and/or horses.
A leader-follower system can be utilized or pastures can
be alternated between sheep and cattle and/or horses.
40. There are numerous other benefits to multi-species
Each species has different grazing behavior that
complements one another.
For example, sheep prefer to eat weeds and short,
tender grasses and clover, while cattle prefer to eat taller
Cattle may offer some protection from predators. 40
41. ALTERNATIVE FORAGES
Some pasture plants have anthelmintic properties, such
as those containing condensed tannins.
Research has shown that sheep grazing tannin-rich
forages have lower fecal egg counts than animals grazing
traditional grass pastures.
The tannins may also decrease the hatch rate of worm
eggs and larval development in feces.
42. Forage species which contain high levels of condensed
tannins include Sericea lespedeza, birdsfoot trefoil, and
Sericea lespedeza is a warm, season legume.
Birdsfoot trefoil is a long-lived perennial legume.
Chicory is a low-growing, leafy perennial.
Generally speaking, trees and shrubs contain higher
levels of tannins than pasture grasses, and tropical
legumes contain more condensed tannins than temperate
43. HEALTHY SOIL
Earthworms have been shown to ingest worm eggs and
larvae, either killing them or carrying them below the soil
Certain types of fungi will trap and kill parasitic larvae.
Dung beetles ingest and disperse manure, thus keeping
eggs and larvae from developing.
Anything that is done to maintain soil health and promote
these types of organisms will aid in parasite control.
Scientists are examining the possibility of feeding
nematophagous fungi to livestock to kill larvae in manure
44. NUTRITIONAL MANAGEMENT
Supplemental feeding should not be overlooked as a
means to control parasites.
Sheep and lambs on a higher plane of nutrition mount a
better immune response to internal parasites than
animals whose nutritional status is compromised.
Animals on low protein diets are more susceptible to
infection because they produce less IgA
Higher levels of protein have been shown to improve the
pregnant ewe's immune response to parasites after
Lambs receiving protein supplementation have reduced
fecal egg counts.
45. ZERO GRAZING
Keeping sheep and/or lambs in confinement (i.e. "zero
grazing") is a means of reducing parasitism and
Under a zero grazing situation, sheep and/or lambs do
not have access to any vegetation for grazing.
They are housed in a bedded barn, dirt lot, or facility with
Feed should be fed off the ground in feeders.
Watering containers should be kept free from fecal matter.
Slotted floors offer the best protection against internal
parasites because sheep generally do not come into
contact with their feces. 45
Genetics is probably the best long term weapon against
internal parasites in sheep.
Some sheep breeds are more resistant and resilient to
They include the Florida (or Gulf Coast) Native and the
hair sheep breeds: St. Croix, Barbados Blackbelly (and its
derivatives), and Katahdin.
In Malaysia – Kalahari Red, Boer etc.
Grazing resistant breeds of sheep with susceptible
breeds, may act to “sweep” pastures and reduce
contamination to susceptible animals.
50. ROLE OF GOVERNMENT, FOUNDATIONS AND AID
Depends on co-ordinated national or even international
responses which only can be achieved through the active
cooperation of governments.
Require stability within the country and a suitable
infrastructure for distribution of funds, communication and
travel for expert personnel.
Can be organized through:
- national government
- local government
Only government have the power to pass and enforce
51. Legislation can be an effective tool:
- can force local authorities to provide safe water and
- make it an offence to import pets or domestic animals
without a certificate
- require farmers to dispose of dead animals appropriately.
52. Role of different organizational levels of health services in sleeping sickness
control.(After World Health Organization, 1986.)