Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

PHYLUM ARTHROPODA
...

1
...

2
...

3
...

4
...
Sarcoptes scabiei
...
Family Ixodidae
...

6
...
Ornithodorus papillipes
...
GENERAL FEATURES OF PHYLUM ARTHROPODA
...

The animals of the phylum Arthropoda live in a greater variety of habitats; and
they can eat a greater variety of foods than the members of any other phylum
...
Arthropods are bilaterally symmetrical, triploblastic animals with segmented body and paired, jointed appendages, from which they got their name (arthropod means jointed foot)
...

2
...
In the inter-segmental regions the cuticle is thin and flexible
...

But the exoskeleton has certain disadvantages
...
This process, called molting, leaves the animal temporarily vulnerable to predators
...
A segmented body
...

The bodies of most arthropods are divided into three regions:
1) the head, is formed by the fusion of some of the anterior segments
...
The
process of the distinct head formation is known as cephalization
...
The thorax and abdomen consist of a variable number of segments
...
The digestive system is a simple tube
...

1

5
...
A hemocoel
(blood cavity) occupies most of the body cavity, and the coelom is small and is filled
chiefly by the organs of the reproductive system
...
From the arteries blood
flows into large sinuses, which collectively make up the hemocoel
...
No capillaries or veins are present
...

6
...

In the more complex arthropods, the successive ganglia usually fuse together
...

7
...
Most of the aquatic arthropods have a system of gills for gas exchange
...

8
...

9
...
The most important are:
Arachnida and Insecta
...
GENERAL FEATURES OF CLASS ARACHNIDA
...
Like insects they achieved big diversity on the planet
...

2) Their body is divided into an anterior part – prosoma, which bears all the
appendages, and posterior abdomen containing respiratory, circulatory, reproductive
and other organs – opisthosoma
...
There are no antennae on it
...

4) Opisthosoma usually consists of 13 segments but they are not externally
visible all in some cases
...

5) Arachnida don’t have true gnathites
...
Besides in the middle gut they have hepatic cecum opening
...
Class is subdivided into several orders
...
GENERAL FEATURES OF ORDER ACARINA
...
About 300 species are bloodsucking ectoparasites of mammals, birds, reptiles, and amphibians, and nearly all are capable of biting human beings
...

1
...
Usually has oval or
circle shape
...
On the head they have 2 pairs of upper maxilla and palps, forming
hypostome or proboscis
...
The mouth
parts and their base, the capitulum, are attached to the anterior portion of the body by
a movable hinge
...
Adult mites have 4 pairs of legs with claws for better attachment to the host
body
...
The sexes are separate
...
Adult female 
Eggs  Larva (without posterior pair of legs, spiracles, tracheae and genital aperture)
 1st molting  Nymph (with 4 pairs of legs and not fully developed genital
ducts) may be also several moltings Adult mite or Imago
...
SARCOPTES SCABIEI
...

The itch mite, S
...
The global prevalence is about 300 million
cases
...

Morphology
...
scabiei is a small, oval, dorsally convex, ventrally flattened, eyeless mite
...
4 mm in length, the
male – 0
...
3 mm
...

Males never do such burrows
...
Then in such grooves it deposits eggs – 20 and more during life
...
The first pairs of
legs terminate in long tubular processes each with a bell-shaped sucker and claws
...
The dorsal surface is ridged transversely and bears spines, scales, and bristles
...
Respiration is by the whole body surface
...

The mites live in slightly cutaneous burrows
...
The burrow is confined to
the corneous layer of the skin
...
The female, during her life-span of 4 to 5 weeks, deposits up to 40 to 50
eggs in the burrow
...
The
hexapod larva either forms a lateral branch or a new tunnel, in which it becomes an
eight-legged nymph
...

The life cycle is completed in 8 to 15 days
...

Human feels very frequently itchy, may scratch this place and open mites
burrows  autoinvasion  spreading of the parasite on the body surface
...
Infectivity is low, and
the infection ends to run a limited course in healthy persons of clean habits
...

Clinical features
...
The lesions appear
as slightly reddish elevated tracts in the skin
...

Scratching may result in bleeding and scab formation, frequently followed
by secondary bacterial infection
...

The intense itching, aggravated by warmth and perspiration, causes scratching,
which spreads the infestation, irritates the lesions, and induces secondary bacterial
infection
...
At first, clinical manifestations may be mild, but after some weeks the skin
becomes sensitized, resulting in an itching, widespread, erythematous eruption
...
This
form of scabies is characterized by extensive, scaling lesions, especially of the extremities, and sometimes by distorted thickening of the fingernails
...

The infection may also be acquired from infected domestic animals, but
there appear to be different strains of the mite, having distinct host preferences, so
that an infection acquired from domestic animals is usually of short duration in
humans
...

4

While infection with S
...
The only way in which a definitive diagnosis of scabies
can be made is by finding the parasites or their eggs
...
Before scrapings are made it is best to examine the skin surface with a hand lens to find the minute burrows of the mite
...
It is therefore best to make scrapings in these regions
...
Alternatively, mineral oil may be applied to the skin before scraping
...
Other methods that
have been proposed for obtaining specimens, but that appear to be less useful than
scraping, include the use of cellophane tape and various synthetic glues
...

Infestation with the itch mite can be eradicated by use of 1 per cent gamma
benzene hexachloride (lindane) in a lotion base
...
One or two additional applications, at weekly intervals, may be necessary to kill mites that hatch subsequent to the initial treatment
...

For 30 years lindane has been used in the treatment of scabies, so it is not surprising that lindane-resistant mites have emerged
...

Prevention of scabies requires the treatment of infected individuals, the sterilization of garments and bedding, and personal cleanliness
...
IXODES RICINUS
...

Class - Arachnida
...

Family - Ixodidae (hard ticks)
Species – Ixodes ricinus
...
Besides
it may be a vector (carrier) of spring-summer encephalitis
...
It is widely spread in the European forests,
also in Russia
...

Morphology
...
The sexes are usually dissimilar
...
The capitulum, or head, projects from the anterior end and is visibly when viewed from above
...

The mouth parts consist of a hypostome, chelicerae, and pedipalps
...
The dorsally paired, chitinous, shaft-like chelicerae act as cutting organs to permit the insertion of the hypostome
...
The eyes, when present, are on or near the anterior lateral margin of the scutum
...

Ixodes ricinus has oval body
...
Another half
of the back is soft-covered by tissues
...

Male is about 2,5 mm in length; brown-colored
...

Life-cycle
...
They may live
for a big period of starvation
...
Adult females may absorb such
volume of blood, which in 100 times higher than their own weight
...
Very high fertility
...
All mites
have high developed sensor organs, especially for the ground vibration, high temperature, CO2 concentration in the air
...

Eggs soil or alive trees  larvae  first feeding on little mammalians 
larvae leave their 1st hosts  moulting  nymph (pupa)  adult mites  big
mammalians like man
...

A condition known as tick paralysis (tick toxicosis) may be induced by the
bite of certain ticks
...
In general, the tick must be attached for at least 4 days
before symptoms begin
...
As far as
is known, only engorging adult female ticks cause tick paralysis
...
But their bites usually pain6

less, because they produce special anaesthetic matter and their attachment to the host
is not visible and asymphtomic
...

Ixodid ticks may be eliminated by exterminating their rodent hosts and destroying their habitats
...
BHC and diazinon have the most rapid immobilizing action but less residual toxicity than the others, giving good control within a
few days and preventing reinfestation for a month or more
...
Suspensions and emulsions are preferable to oil solutions
...
It is advisable to start spraying in the spring, but a subsequent treatment at the peak of population in the summer is necessary
...

6
...

Morphology
...

The soft ticks are primarily ectoparasites of birds, less commonly of mammals
and humans
...
The sexes are similar: there is no dorsal plate, the capitulum is not visible
dorsally, the spiracles lie in front of the third pair of coxae
...
This material contains spirochetes
(Borrelid) in infected vectors
...

Ornithodoros moubata of Africa, an oval, yellowish-brown, tuberculated, leathery tick, 8 to 9 mm, is the best known parasitic species of this genus
...
The bites of
both nymphs and adults produce hard, red wheals that remain painful for 24 hours
...

Several other species of Ornithodoros are vectors of local types of relapsing fever throughout the world
...

Both sexes of hard and soft ticks are bloodsuckers
...
It then drops off the host to deposit, in 14 to
41 days, 2000 to 8000 small, oval, brown eggs and dies in 3 to 36 days after
oviposition
...
After 2 to 7 weeks, larvae with three pairs of legs emerge from the eggs
...

Hard ticks have a single nymphal stage, but soft ticks may have several
...
The life cycle is usually completed in 1 or 2
years, occasionally in 3
...
The same or different species of mammal
may serve as hosts for the various stages
...

During their larval, nymphal, and adult stages, ticks are intermittent parasites of
animals and spend most of their existence on the ground
...
Ticks
are susceptible to sunlight, desiccation, and excessive rainfall, but are resistant to
cold
...

Disease:
Ticks harm humans and lower animals by
1) the mechanical injury of their bites, local itching, or even the formation of
nodules,
2) by the production of tick paralysis,
3) by the transmission of bacterial, viral, rickettsial, spirochetal, and protozoan
diseases
...
Its insertion produces an inflammatory reaction of the perivascular tissues of the corium, with local hyperemia, edema, hemorrhage
...
If the capitulum is broken off in the
skin during removal of the tick it may cause a festering wound
...

The disease manifests itself as a progressive, ascending, flaccid motor paralysis
that is due to a neuromuscular blockade at the presynaptic level, peripheral nerve involvement caused by the tick toxin
...

The disease has a rapid onset, with malaise, vague body pains, slight or no fever
...
Sensory signs are very rare in tick paralysis
...
Children are usually affected; occasionally aged adults are affected
...

The important diagnostic reminder is simply to think of the possibility of tick
paralysis when faced with a clinical picture such as this and to search for the tick, especially in the area of the neck covered by hair
...

The ticks may be removed from the skin by gentle traction after applying chloroform, ether, alcohol, gasoline, kerosene, glycerol, ethyl chloride or a glowing match
or cigarette to the tick
...
Allow two drops of clear fingernail polish to fall
from the brush and completely cover the tick
...
Care should be taken not to break off the capitulum
in the wound
...
Paralysis,
if present, soon subsides after the removal of the tick
...

Argasid ticks are best combated by destroying their nests or lairs
...
More than one
application is required, since these insecticides are ineffective against the eggs
...
Inhabitants should avoid sleeping on the floor
...
(1) The breeding grounds may be
destroyed by burning and clearing the tall grasses and underbrush, by cultivation, and
by sheep grazing, and (2) the rodent hosts may be destroyed
...
Ground sprays with chlorpyriphos or ultra-low-volume sprays of
propoxur can also be used
...

Treatment
...
Palliative treatment includes the application of alcohol, ammonia, baking
soda, alcoholic iodine, camphor, or a saturated solution of salicylic acid in alcohol
with a little sweet oil
...


9

PHYLUM ARTHROPODA
...

1
...

2
...

a) Pediculus humanus capitis
...

c) Phthirus pubis
...
Order Aphaniptera
...

4
...

a) Culex mosquito
...

c) Musca domestica
...

1
...
The insect body is well protected by a tough
exoskeleton, which also helps to prevent water loss by evaporation
...
The insect body consists of three distinct parts - head, thorax, and abdomen
...
At the free end of the head is the mouth
...
They are collectively
called the mouth parts, which may be adapted for piercing, chewing, sucking, or
lapping
...

Labrum is a flat structure
...
Mandibles lie immediately
beneath the labrum, one on either side of the mouth
...

Maxillae lie posterior to the mandibles
...
The maxillary palp is sensory in function
...
Hypopharynx lies in front of the labium between the two maxilla
...

b) Thorax
...
The thorax is
composed of three segments: prothorax, mesothorax and metathorax
...
A leg consists of 5
segments: coxa, trochanter, femur, tibia and tarsus
...
Trochanter is a small triangular piece
...
It is the largest segment in the leg
...
The tarsus is the last segment of the leg
...
The last piece terminates in a pair of claws
...
It is used for gripping on surfaces
...
They arise from the mesothorax and metathorax as
lateral expansions of the cuticle
...
They serve as protective covers for the second pair of wings and are
known as tegmina
...
They are kept folded under the tegmina when not in use
...
Projecting from the side of the last segment
is a pair of many jointed processes called anal cerci
...
In the female the abdomen is broader than that in the
male
...
Ten pairs of slit-like openings called
spiracles or stigma lie on the sides of the body
...


Fig
...


3
...
The mouth leads into the buccal cavity
...
In blood–sucking insects the muscular pharynx
acts as a suction pump
...
The crop leads into a muscular sac called gizzard
...

The foregut is continued as the midgut or distensible stomach
...
They secrete digestive fluids
...
The junction of the midgut and hindgut
is marked by several fine Malpighian tubules, the excretory organs
...
The rectum opens out by
the anus
...
They lie on either side of the crop
...
Mandibles cut the food into small pieces
...

4
...

5
...
Several molts
occur during development
...
In others there is a complete metamorphosis with four distinct stages in
the life cycle: egg, larva, pupa, and adult
...

Lice are small, dorso-ventrally flattened, wingless insects that have incomplete
metamorphosis
...

The parasitic lice of humans include three species or varieties:
1) Pediculus humanus var
...
humanus (body louse),
3) Phthirus pubis (crab louse)
...

Phylum - Arthropoda
Class - Insecta
Order - Anoplura
Genus - Pediculus
Species – Pediculus humanus var
...
humanus
Diseases
...
Vectors of epidemic typhus, trench fever and relapsing fever
...
The human body or head louse, P
...
These lice are exclusively
human parasites and have worldwide distribution
...

The body and head lice readily pass from host to host, but the crab louse changes its position infrequently
...
Both sexes take a blood meal
...
Moist heat at 60°C destroys the eggs in 15 to 30
minutes
...
The head louse, which is easily transmitted by brushes, combs, and hats, is
most prevalent in schoolchildren
...
The body louse is
transmitted by contact or by clothing or personal effects infested with nits
...

Lice are dorso-ventrally flattened insects, sufficiently large to be detected easily
with the naked eye
...

The flattened, elongated, grayish-white body has an angular ovoid head, a fused
chitinous thorax, and a segmented abdomen
...

Each of the three fused segments of the thorax bears a pair of strong, segmented
legs that terminate in a single hook-like claw and an opposing tibial process for gripping hairs or fibers
...

The body louse is more robust than the head louse; both are 2 to 3 mm in length
...

The whole life cycle occurs on the human host
...
capitis infests the scalp
...
The operculated, white eggs or nits are quite
small and glistening white and may be seen with the naked eye
...
Wood’s light, used in diagnosis of dermatologic conditions, is a useful tool for screening large groups of people
...
Both larvae and adults feed
on blood obtained by their piercing mouth parts and a pumping device located in the
pharyngeal region
...
h
...
h
...
Its life history is similar to that of the head louse, which it
13

closely resembles
...
The eggs hatch
in 5 to 11 days at 21° to 36°C
...
The nymph develops
within the egg case and emerges through the opened operculum
...

The average life cycle of the body or head louse covers 18 days
...

The total number of eggs deposited during the lifetime has been estimated at 300
for the body louse, 140 for the head louse
...

The irritating saliva, injected during feeding, produces a roseate elevated papule
accompanied by severe itching
...
Individuals vary in sensitivity
...
Severe infestations may produce scarring,
induration, pigmentation, and even ulceration of the skin
...
Itching
is the earliest and most prominent symptom, and the sequelae of scratching are the
most characteristic signs
...
The head louse and the crab louse have never been incriminated in disease
transmission
...

Lice become infected with the causative organism, Rickettsia prowazeki, by ingesting the blood of a diseased person
...
The louse remains infective throughout its shortened life
...

The spirochete Borrelia recurrentis, the causative agent of epidemic relapsing
fever, when ingested with the blood of the patient, multiplies rapidly throughout the
body of the louse, which remains infective throughout its life
...
People are infected by the contaminative method, the crushed body of the louse coming in contact with the bite
wound or abraded skin
...
quintana,
was present in epidemic form in World War I and later in endemic form in Europe
and Mexico
...

Diagnosis
...
Louse eggs will fluoresce
under ultraviolet light, so an ultraviolet lamp, or Wood's light, is useful in detecting
14

presence of infestation, especially when screening large numbers of people
...

Head or body lice are transferred from one person to the next by direct
contact or by contact with clothing, hats, or hair from “lousy” individuals
...
Cloth - covered seats
in theaters, railway carriages, and other public places may be a source of infestation
...
This is important in the transmission of louse-borne diseases
...

Mass delousing methods are designed not only to exterminate the lice but also to
control the epidemic diseases that are transmitted by lice
...

For the mass delousing of Chilians, it is much simpler to administer insecticidal
powders such as 10% gamma benzene hexachloride or 10% DDT simultaneously to
the body and clothing
...

Strains of lice resistant to DDT have been reported in Korea, Egypt, Japan, and
North China
...
Exposure of infested clothing to temperatures
of 70°C or greater for 30 minutes will kill lice and eggs
...

Phylum - Arthropoda
Class - Insecta
Order - Anoplura
Genus - Phthirus
Species – Phthirus pubis
The pubic, or crab, louse, P
...

Morphology
...
8 to 1
...

Phthirus is somewhat shorter and broader than Pediculus
...

Life-cycle
...
While the head louse moves about rapidly, the pubic louse is much more seden15

tary in its habits
...
Recent sexual promiscuity has led to an increase in the prevalence of this louse
...

Phylum - Arthropoda
Class - Insecta
Order - Aphaniptera
Genus - Pulex
Species – Pulex irritans
Fleas are bloodsucking ectoparasites that, for feeding purposes, temporarily infest mammals and birds
...
It also infests hogs,
calves, dogs, rats, mice, cats, small wild rodents
...

Fleas are small, brown, wingless insects, 2
...
5 mm, with laterally compressed bodies
...
Each segment of the three-segmented thorax bears a pair of
powerful legs terminating in two curved claws
...

The hosts of fleas are domesticated and wild animals, especially wild rodents
...

The life-span is about a year under favorable conditions of cool, moist temperature, but the maximal survival period apart from the host is 38 to 125 days, depending
upon the species
...

The adult fleas feed on their hosts, while the larvae live on any nutritive debris,
particularly dried blood and the feces of the adults
...

Fleas have unusual leaping powers, which enable them to transfer readily from host
to host
...
The small, ovoid, white or cream-colored eggs
...
5 mm in length, are laid in the hairs or in the habitat of the host
...
Those deposited on the host usually drop off before hatching
...
In 2 to 12 days the larva emerges from the egg as an
active, wormlike, white, eyeless, legless, bristled creature of 14 segments, approximately 4
...
It has a chewing mouth
...

16

The larval period usually lasts 7 to 30 days, during which time it undergoes two
or three molts, the last being within the silky pupal cocoon
...
When the development of
the pupa is completed, the adult flea breaks out of the cocoon
...

The incidence of human infestation varies with hygienic standards and the association of man with animals
...

Humanity is an important host of Pulex irritans, Ctenocephalides canis, C
...

Fleas are of medical interest chiefly in connection with the transmission of
plague and endemic typhus
...

Humans acquire plague caused by the gram-negative bacillus, Yersinia pestis,
from the fleas that transmit the infection from rat to rat
...

On the death of the rat near human habitations, the infected fleas seek new hosts,
either humans or other rats
...
"
Endemic or murine typhus is transmitted from rat to rat and from rat to human
being by fleas
...
Infection is transmitted by the contamination of the bite wound or abraded skin with the
infectious feces or the crushed bodies of the fleas
...
P
...

The cutaneous irritation caused by the salivary secretions of the flea in different
persons varies from no reaction to a raised, roseate, slightly edematous lesion, and in
sensitive individuals to a more extensive inflammation or papular rash
...

Environmental control of fleas consists of spraying rat runways, harborage areas, floors, and other areas with one of the following solutions (chlordane, diazinon,
lindane) in kerosene, fuel oil
...
Surgical removal of the flea is indicated
...

CULEX AND ANOPHELES MOSQUITOS
...

They live in houses, in cities and farms, and are abundant also in rural areas
...

Each species has an effective flight range between the breeding grounds and the
sources of the blood meal, as well as a maximal range—from 1 to 3 miles for Anopheles, up to 10 miles for Culex, and 50 to 100 miles for some Aedes, often windblown
...

Certain species are preeminently anthropophilic (human) in their bloodsucking
preferences, and others are essentially zoophilic (animals)
...

Predilection for humans determines the importance of an anopheline species as a
vector of malaria
...
As a rule, females cannot produce fertile eggs without ingesting blood
...
The biting
activities of the different species vary with age, time of day, and environment
...

Certain species frequent houses for feeding and resting, while other species enter
houses only for feeding and spend their resting periods elsewhere
...

Mating is preceded by the prenuptial swarming of the males in some species
...

The maximal number of eggs deposited at one time is from 100 to 400
...
The life - span of male
mosquitoes is seldom more then three weeks, they die after impregnating the females
...

The females of species frequenting houses may hibernate as adults during winter, and a few species pass the winter in the egg or larval stage
...
Birds, bats, toads, frogs, and dragon-flies are
natural enemies of the adults, and waterfowl, fish, and aquatic insects prey on the larvae and pupae
...

Mosquitoes are distinguished from other flies by:
1) the elongated mouth parts, adapted in the females for piercing and sucking
blood,
2) the long, 15-jointed antennae, plumose in the males and pilose in the females,
3) the characteristic wing venation, with scales
...

The head is small and round bearing a pair of antennae, a pair of compound eye
and mouth-parts
...
The mouth-parts consist of a
median long thick proboscis and a pair of maxillary palps situated one on each side
of the proboscis
...
Mouth-parts are well developed in females because it sucks blood
...
The salivary glands are located in the prothorax
...

Thorax consists of three segments - prothorax, mesothorax and metathorax
...

Mesothorax bears a pair of membranous wings which are used for flight
...
The coloration and
pattern of the thoracic scales and bristles are useful in differentiating genera and species
...
Anus is in eighth and genital aperture in
the ninth segment
...
In
male the tergum of ninth segment is bilobed on which is a clasper
...

Life-cycle
...
Most species use fresh
water for their aquatic stages, but some, chiefly culicines, breed in brackish or salt
water
...
These are egg, larva, pupa and imago or adult stage
...
Eggs
...

a) Culex lays eggs in dirty water
...
The
eggs are cigar shaped and form a floating raft by cementing together in a group
...
Each
egg is free and is provided with a lateral float
...

2
...

Larva of mosquito is also called wriggler because it swims spirally in water
...
Head is provided
with a pair of compound eyes, a pair of simple eyes, two antennae and mouth-parts
...
The thorax is broad, unsegmented without legs
19

but is provided with groups of lateral bristles
...

a) A long respiratory siphon is present on the dorsal side of the 8th segment in
the case of the Culex larva
...
The respiratory siphon only touches the water surface and the head hangs
down in the water
...
It is about 1
...
It molts 4 times and changes into a pupa
...
The respiratory siphon is
absent
...
The larva hangs horizontally by
means of bristles from the surface of water
...
The development is slow and the larval life lasts from two for four weeks
...
Pupa
...
The body is like a comma
...

a) In Culex pupa from the dorsal surface of cephalothorax come out two long
respiratory trumpets by means of pupa remains attached with water surface
...
The pupa is very active but it does not feed as it has no mouth and anus
...
This stage is not feeding stage but during this period internal
organs are formed
...
Respiratory trumpet is small with a wide funnel
...

4
...

In the life-cycle of mosquito the egg hatches out into a larva which does not resemble the adult and swims actively in water
...
After molting four
times it forms the pupa
...
This process is called histolysis;
b) some other cells called histoblasts start forming the adult structures
...
In this way within the covering of the pupa
are formed various internal organs and ultimately an imago
...
Imago
...

a) Imago of Culex has the following features:
- body is grey colored
- wings uniformly colored
- in the female maxillary palp is small (about 1/3 of the length of proboscis)
- during the rest body lies parallel to surface
...

Diseases, clinical features
...
The intermittently injected saliva may contain substances that
stimulate capillary dilation or slow coagulation
...
The ordinary
bite is followed by erythema, swelling, and itching
...
Salivary antigens elicit immediate
allergic as well as delayed-type skin reactions
...

In addition, some day-flying and day-biting mosquitoes carry the eggs of the
myiasis-producing warble fly to the skin of humans and other mammals
...

Aedes carries virus-like bacteria which are responsible for causing yellow fever
and dengue
...

Culex, Anopheles and Aedes are responsible for carrying of the infective stage
of W
...

Aedes, Culex and Psorophora mosquitoes are associated with encephalitis and
dermatobia
...

The only vectors of human and simian malaria are anopheline mosquitoes, while
both anopheline and culicine mosquitoes carry avian malaria
...
Some 110 species have been associated with the transmission of malaria, of which 50 are of general or local importance
...

The suitability of a species as a potential vector may be determined by recording
the percentage of infected mosquitoes after feeding on a malarial patient, but its importance as a vector is ascertained by obtaining the index of natural infections, usually from 1 to 5%, in female mosquitoes collected in houses in a malarial district
...

Mosquito control requires knowledge of the habits of the particular species, the
climate of the country, and the habits and socioeconomic status of the population
...

More than one method may be required
...

a) Control of breeding places
...
The destruction of
breeding grounds, essentially an engineering problem, gives permanent results but
involves high initial and maintenance costs
...
Extensive drainage operations are seldom practicable, but
they are of value at selected sites
...

Changing the water level by intermittent flushing has proved useful for controlling species that breed in impounded waters and flowing streams
...

b) Destruction of larvae and pupae
...

Aquatic, surface-inhabiting larvae can be killed by application of oils or other organic
surface films that interfere with the gas exchange of larvae or affect the emergence of
adults
...
These include:
(1) the chlorinated hydrocarbons such as DDT, BHC, and dieldrin,
(2) the organic phosphates, such as malathion and parathion,
(3) the carbamates, such as landrin and bendiocarb,
(4) the pyrethroids, such as permathrin and decamethrin
...
In addition, insecticide-impregnated bed nets have recently been shown to be quite effective for control of malaria transmission
...

This practice was based upon the knowledge that many anopheline vectors entered buildings for their human blood meals and rested on the walls before or after
22

feeding, thereby coming into contact with the insecticide
...
Thus, the effort of human beings to control insect vectors goes
on—a never-ending battle
...

The problems associated with insecticide use have also stimulated new approaches to vector control
...
) in lakes and ponds, use
of hormones that inhibit insect growth and development, other hormones that attract
insects (pheromones), and toxins produced by bacteria (Bacillus thuringiensis)
...

c) Destruction of adults and protection from mosquitoes
...

Effective repellents, such as butopyronoxyl (Indalone), dimethyl phthalate, Rutgers 612, and diethyltoluamide (Off), are effective for several hours
...

Phylum - Arthropoda
Class - Insecta
Order - Diptera
Genus - Musca domestica (housefly)
The common housefly M
...
The eggs are laid in lots of about 100 in manure or refuse
...

Its larvae are responsible for an occasional intestinal and genitourinary myiasis
...

Therefore, it may serve as a mechanical vector of pathogenic bacteria, protozoa,
and helminthic eggs and larvae, especially of enteric disease organisms
...

Control is a community measure, since flies travel considerable distances, but
screening and trapping protect the individual home
...


23

Pyrethroid-coated fiberglass strips can be hung in barns
...

In addition, in this setting, the release of a microhymenopteran parasite,
Spalangia endius, has been effective

---