This is a presentation on helminths in various population groups around the world. Broadly, the term "helminth" refers to parasitic worms that can be classified into 2 phyla: Nematoda (roundworms) and Platyhelminthes (flatworms). The phylum Platyhelminthes is further divided into Cestoda (tapeworms) and Trematoda (flukes). Helminthiasis is a major public health threat throughout Asia, sub-Saharan Africa, and the Americas. It has been estimated that more than 1 billion people worldwide are infected with at least 1 species, and many are coinfected with 2 or more parasites.[3,4] Most of those affected represent the world's poorest and most vulnerable populations. Economist Paul Collier has termed this population "the bottom billion." Poor access to healthcare, sanitation, and clean water make this group particularly susceptible to infection. This article will discuss how helminth infections affect arguably the most vulnerable group of all: neonates and young children. In this first case, both EB and his mother demonstrate consequences of hookworm infection. Two species of hookworm cause disease in humans. Necator americanus is found in the Americas, sub-Saharan Africa, and parts of Asia. A duodenale occurs in the Mediterranean, parts of the Middle East, and Asia. Between 740 million and 1.3 billion people worldwide are probably infected.[2,5] Hookworm eggs are found in soil contaminated with feces. The larvae hatch, develop in the soil, and penetrate the skin of a human host. As the larvae migrate through the host's skin, a pruritic rash may erupt. The larvae then travel through the bloodstream to the lungs, where they penetrate the alveoli and are swallowed by the host. They mature in the small intestine, where the main manifestations of disease occur. The parasite's mouthpiece contains sharp hooks for attaching to the duodenal wall. Once attached, hookworms release anticoagulant peptides and serine proteinase inhibitors, which contribute to anemia and malabsorption of nutrients, respectively. After attachment, a single worm may consume 0.3-0.5 mL of blood per day.[6,7] Heavy infection can therefore result in profound anemia as well as protein loss, leading to malnutrition and anasarca. In endemic areas, coinfection with multiple types of helminthes is common and increases nutritional losses. In general, helminth infections are more common in children than in young infants. Nevertheless, maternal infection is common and can profoundly affect neonatal health. In the case of EB, his mother had a history of anemia and a previous preterm delivery. Iron-deficiency anemia induced by hookworms poses particular problems for pregnant, breastfeeding, or menstruating women, who have increased iron demands. Iron-deficiency anemia during pregnancy is a known risk factor for intrauterine growth restriction, low birthweight, preterm birth, and low neonatal iron stores.[4,8,9] In areas with poor resources to care for preterm or low-birthweight infants.

1. HELMINTHOLOGY
Helminthology it is the
science that deals with study
of the helminths.
Helminths are a Greek means
that are all worms that live as
parasite.

2. General character of helminths
1.All are multicellular bilateral symmetrical
animal.
2.Very few worms cause infection are potential
dangerous.
3.The ability of parasite to produce clinical
manifestation usually associated with:
A. Number of the parasites

4. B. Location or occurrence
of the parasite

5. C. Reinfection
D. The host immunity
4.Unlike protozoa, most helminths are unable to
multiply within the host ( fertilization may
occur within the host but multiplication and
formation of embryo occur out side the host
so usually is light infection).

6. 5.Many helminths have limited distributions because:
A. They require optically climate.
B. Presence of reservoir or vector (stable).
C. (So the infection may refer to certain area in the world).
6.The majority of helminths are transmitted through :
A. Contamination of environment as contaminated food.
B. Skin penetration.
C. Arthropod bits (insects).
7.Types of life cycle :
A. In some helminths the life cycle is direct
In direct life cycle it is relatively simple, involving only one host and a
brief period of development of an infective transfer stage
(Ex. Enterobius vermicularis).

8. In a group referred to soil transmitted helminths
the life cycle involve only one host man,but
the infective transfer stage larvae remaining in
the egg that require period of development in
the soil and the soil function as intermediate
host Example:
Ascaris lumbricoides
Trichuris trichura

10. B. In some helminths the life cycle is indirect:
It involves essential development in one intermediate host as in filarial and
most tapeworms. such as E. granulosus

11. often in two intermediate hosts are in most
trematodes the first is being snail or other
molluscan and the second an animal or plant
that eaten by people (such as larval of lung
flukes in fish or other on aquatic vegetation).
C. In addition to above certain nematodes, cestodes
and trematodes include in their life cycle a
special kind of transmission known as
paratenesis involving paratenic host. As in the
case of T. canis

13.  In prey-predator relationship paratenic host acquire
the larval stage after it has developed to infection
stage in soil or intermediate host and provide for:
 protection and the
 Availability to its final host.
 The example of paratenesic was coined seen in
the enzootic cycle of toxocara canis a cause of
visceral larva migrant

14. 8.They obtained their nourishment from host :
 Tissue known: tissue parasite.
 Intestinal content known: Intestinal parasite.
 By absorption of predigested nutrition as in
tapeworms through their body wall as the worm
that have no digestive system .As in Cestods

16. 9.They are parasites have protective mechanism
which prevent the
host from damaging the outer surface
which may be destroyed by granulocytes and
macrophages.
 Some adult worms secrete large amount of soluble
antigenic material during their secretion process,
which play important role in both immunity and
pathogenicity.

17. 10. sharing many of parasite infection with animals is termed
zoonosis (Zoontic disease is sharing of disease between
both
animal and human, in other word is the disease of animal
but
can infect human.
11.Pathogenically depend on:
 Species of parasite.
 Intensity of parasite.
 The type of tissue invades.
 Immunity of the host.

18. 12.The injury which produced by parasites usually takes
place due to two factor:
A. Mechanical or physical action.
B. Chemical or toxic action.
(Of both adult and larvae)
A.Mechanical or physical action
i The movement and migration of parasite (worm)
which cause irritation of intestinal wall.

20. ii Size and number of worm which cause obstruction of intestine,for example
size of Taenia species and number as Ascaris lumbricoides

22. iii Pressure:
For example hydatid cyst, larva of Echinococcus granulosius may reach a ball size may cause
pressure on tissue and this pressure cause atrophy of infected organ.

23. Vi/ Attachment: Most
worms are provided
with attachment to
organs and these organs
may cause lesions that
could be secondary
bacterial infection.
V/ Sharing host nutrient
that lead to weight loss.

24. B. Chemical or toxic action
Helminths secretes a large amount of antigenic material:
i/ Tissue lysins.
ii/ Haemolysins.
iii/ Anticoagulants.
(These substances lead to local and general reaction)
*Local reaction
Due to infiltration of esinophils which may lead to:
-Inflammation.
-Necrosis.
-Repairing.
-Encapsulation.
So destructive of parasite.
*General reaction
Direct: a) Chemotactic action (absorption of toxins).
b) Allergic response.
Indirect: Nervous reflexes.

25. Nematodes
General characters:
The
general characteristics
of nematodes are as
follow :
1. Elongated, cylendrical ,
Unsegmented worms
(parasite) .

26. 2. The sizes with great variations ( Smallest is T.
Spiralis , the Largest is D.medinensis ) .

27. 3. The body is covered by tough cuticle , hypodermis & somatic Muscular .
4. They have complete digestive tract & genital organs .
5. In the mouth cavity ( teeth , cutting organs , lips ) useful for attachments ,
penetrating tissues & damage of host tissue .

28. 6. All nematodes are diecious ( seprate sexes ),
parthenogenetic.
7. Males are smaller than females ( ventrally
curved with bursa,Spicules, alae….. et.).

30. 8. Female nematodes are divided as follows:-
A. Viviparous , e.g. T. spiralis .
B. Oviparous , A.lumbricoides, A.duodenale,
E.vermicularis.
C. Ovo-viviparous , e.g. S.stercoralis .

31. Classification of nematodes
according to habitat of adult worms:
a. Intestinal b. Extraintestinal
1- small intestine 1- Lymphatic system
A.lumbricoides W.bancrofti
A.doudenale
N.americanus 2- Subcutaneous tissues
S.stercoralis
T.spiralis Onchocerca velvulus
2- Large intestine 3- Lungs
S.stercularis
E. vermecularis 4- Conjunctiva
T. trichiura Loa loa .

32. Classification
1-Intestinal 2- Extraintestinal .
1-Intestinal nematodes :
a. A.lumbricoides: Gint intestinal round worm.
b. T.trichiura : whipworm .
c. E.vermeculsris: pinworm
d. S.stercoralis : human threadworm .
e. Hookworms : A.duodenale
N.amercanus
f. T.spiralis : Trichina worm
2-Extraintestinal Nematodes:
A. Filarial worms
B. Larva migrans ( L.M.)
1. Cutaneous L.M.
2. Visceral L.M.

33. Life cycle:
There are 5 successive
Fundamental stages :
4 larval stages and adult
stage with growth & molt of
cuticle
between the 2 stages .
Type of nematode larvae :-
1-Rhabditiform larvae:
a.Feeding , non infective stage
b.Diagnostic structure called
rhabditiform esophagus with
Musclar bulb.

34. 2-Filariform larvae:
a.Non feeding , infective stage
b.Thread –like, non bulbed elongated esophagus .

35. Life cycle of nematodes:
Man is the optimum host for all the nematode
Parasites. They pass their life cycle in one host
except the superfamilies
Filaroedia and Dracunculoidia , where two hosts
are required. Insect is the second host in case
of Filaroidea and cyclops is the second host in
case of Dracunculodea .

36. Mode of infection of Nematodes :
-
1-By ingestion of the followings:-
A. Embryonated eggs contaminating food and drink, as in the case of
A. lumbricoides, E.vermacularis &T.trichiura
B. Growing embryosin an intermediate host( infected cyclopes)
In D.medinensis .
C. Encysted embryos in infected pigs flesh as in T.spiralis .

37. 2-By penetration of skin:-
The filariform larvae
boring through the Skin
, as in A.duodenal ,
N.americanis and
S.stercoralis .