This document discusses the epidemiology and prophylaxis of helminthiasis. It defines key terms like epidemiology and helminths. It then classifies and describes different types of helminth infections caused by roundworms, tapeworms, and flukes. The document outlines the prevalence, transmission, symptoms, and prevention/treatment of diseases caused by these parasites, including schistosomiasis, filariasis, ascariasis, taeniasis/cysticercosis, and echinococcosis.

1. Epidemiology and prophylaxis
of helminthiasis
Dr. Liukhurova Amina

2. What is EPIDEMIOLOGY?
⚫It is the study of distribution of diseases
in a particular community or district.
⚫Study and analysis of patterns, causes and
effects of health and disease state in
particular population.
⚫The data are best obtained either directly
in a field or from a source such as hospitals
or regional health clinic records

3. Classification:
Epidemiology of parasites are mainly
divided into 2 types:
⚫Protozoan Epidemiology
⚫Helminthic Epidemiology

4. What are Helminths?
⚫Helminths (Greek meaning worms)
⚫Helminths are mostly parasitic
worms ; but some are free living.

5. CLASSIFICATION OF HELMINTHS
Two major phyla of helminths:
⚫NEMATHELMINTHES (Roundworms): Includes major
intestinal worms like soil-transmitted helminths Ascaris,
and the filarial worms that cause lymphatic filariasis.
⚫PLATYHELMINTHES (Flatworms): Includes two classes
TREMATODA (Flukes) Leaf like; e.g., Schistosomes and
Fasciola
CESTODA (Tapeworms) Ribbon like; e.g., Pork
tapeworm
that causes Cysticercosis.

6. HELMINTH INFECTIONS
Roundworm infection(Nematodiasis):
⚫Filariasis (Wuchereria bancrofti, Brugia
malayi infection)
⚫Onchocerciasis (Onchocerca volvulus
infection) Also known River blindness or
Robles disease.
⚫Soil-transmitted nematode disease:
It includes ascariasis (Ascaris lumricoides
infection).
It is an intestinal roundworm.

7. Tapeworm Infection (Cestodiasis):
⚫Echinococcosis (Echinococcus infection):
Infection through ingestion of parasitic egg with
contaminated food, water or soil.
⚫Hymenolepiasis (Hymenolepis infection):
Caused by the introuction of tapeworm species;
Hymenolepis nana or Hymenolepis diminuta.
⚫Taeniasis/ Cysticercosis (Taenia infection):
Acquired by humans through ingestion of
tapeworm larval cysts (cysticerci) in undercooked
pork or beef.

8. Trematode infection (Trematodiasis):
⚫Schistosomiasis/Bilharziasis (Schistosoma
Infection): Caused by parasitic worm that live in
certain types of freshwater snails.
⚫Amphistomiasis (Amphistoma infection):
It can be transmitted via penetration of skin or by
direct ingestion through contaminated food or
water.
⚫Fascioliasis (Fasciola infection)
It is a water and food borne zoonotic disease
Caused by two parasites: F. Hepatica and F.
Gigantica.

9. PREVALENCE OF HELMINTHISIS
Roundworm infected diseases:
FILARIASIS:
Caused by Wuchereria bancrofti, Brugia malayi
GLOBAL SCENERIO:
⚫An estimated 120 million people in tropical and
subtropical areas of the world are infected with
lympathic filariasis; of these, 25 million men have
genital disease (most commonly hydrocoele) and
almost 15 million; mostly women, have
lymphoedema or elephantiasis of the leg.

10. ONCHOCERCIASIS (River Blindness):
Caused by Onchocera volvulus
Symptoms include itching, bumps under skin,
blindness.
GLOBAL SCENERIO:
oAbout 37 million people are infected with this
parasite, about 300,000 of those have been
permanently blinded.
oAccording to 2002 WHO report, Onchocerciasis
has not caused a single death, but its global
burden is 987,000 Disability Adjusted Life Years
(DALYs).

11. ASCARIASIS:
Most common helminthic human infection
worldwide, causative agent Ascaris lumbricoides.
GLOBAL SCENERIO:
⚫Highest prevalence in tropical and sub-tropical
regions where warm wet climates provide
environmental conditions that favour year-round
transmission of infection and areas with inadequate
sanitations where suboptimal sanitation practices
lead to increased contamination of soil and water.

12. INTENSITY OF SOME MAJOR HELMINTHIASES:
SCHISTOSOMIASIS:
⚫S. haematobium infection intensity reduces with age
⚫Children are more highly affected and infected than
adults
⚫Low infection probability for males than in females
⚫The incidence is usually more among those people
who constantly get in contact with the schistosome
infected waters through activities such as farming,
fishing, swimming and washing.
⚫Death rate is very low or negligible.

13. FILARIASIS:
⚫Repeated mosquito bites over several months to
years are
needed to cause Lympathic Filariasis.
⚫This disease cause a negligible death rate but it can
cause permanent disabilities
⚫It affects both males and females
ASCARIASIS:
⚫It infects all ages of human. But mostly children of
2-10 year of age and intensity decreases over 15 years
of age.
⚫Most prevalent in areas of low socioeconomic
status and thus poverty and malnutrition
⚫It exerts a chronic effect on host nutrition.

14. TAENIASIS/CYSTERCOSIS:
⚫Most often in rural areas of developing countries,
where pigs roam freely and eat human faeces and
where hygiene practices are poor
⚫Worldwide as of 2010 it caused about 1,200 deaths,
up from 700 in 1990.
⚫The mean age at death was 40.5 years (range 2–88)
⚫The 33 US-born persons who died of cysticercosis
represented 15% of all cysticercosis-related deaths.
The cysticercosis mortality rate was highest in
California, which accounted for 60% of all
cysticercosis deaths

15. ECHINOCOCCOSIS:
⚫Cystic echinococcosis is rarely fatal.
Occasionally, deaths occur because of
anaphylactic shock or cardiac tamponade in
heart .
⚫Hydatid disease is seen in subjects of any
age and sex, although it is more common in
those aged 20–40 yrs
⚫It is a disease of rural areas where farming
is practiced traditionally.

16. SCHISTOSOMIASIS:
The manifestations of schistosomal infection
vary over time as the cercariae, and later
adult worms and their eggs migrate through
the body.
Dermatitis
⚫Itchy papular rash
⚫1-3cm big round bumps
⚫The rash can occur between the first few
hours and a week after exposure and lasts for
several days.
CLINICAL SYMPTOMS, MORPHOLOGICAL AND
PHYSICAL ALTERATIONS

17. ⚫A similar, more severe reaction called
"swimmer's itch" reaction can also be
caused by cercariae from animal
trematodes that often infect birds.
Katayama fever:
⚫Acute schistosomiasis (Katayama fever)
may occur weeks or months after the initial
infection as a systemic reaction against
migrating schistosomulae as they pass
through the bloodstream through the lungs
to the liver.

18. Symptoms include:
⚫Dry cough with changes on chest x-ray
⚫Fever
⚫Fatigue
⚫Muscle aches
⚫Malaise
⚫Abdominal pain
⚫Enlargement of both the liver and the spleen
⚫The symptoms usually get better on their own but
a small proportion of people have persistent weight
loss, diarrhea, diffuse abdominal pain and rash.

19. Chronic Disease:
⚫In long established disease adult worms lay eggs
that can cause inflammatory reactions
⚫The long term manifestations are dependent on
the species of schistosome as the adult worms of
different species migrate to different areas.
⚫ Many infections are mildly symptomatic, with
anemia and malnutrition being common in
endemic areas.
Genitourinary disease:
⚫The worms of S. haematobium migrate to the veins
around the bladder and ureters

20. ⚫This can lead to blood in the urine 10 to 12
weeks after infection.
⚫Over time, fibrosis can lead to obstruction
of the urinary
⚫Bladder cancer diagnosis and mortality are
generally elevated in affected areas, and
have efforts to control schistosomiasis in
Egypt have led to decreases in the bladder
cancer rate. tract, hydronephrosis and
kidney failure.

21. ⚫The risk of bladder cancer appears to be
especially high in male smokers, perhaps
due to chronic irritation of the bladder
lining allowing it to be exposed to
carcinogens from smokin
⚫In women, genitourinary disease can also
include genital lesions that may lead to
increased rates of HIV transmissiong

22. Gastrointestinal Disease:
⚫The worms of S. mansoni and S. japonicum
migrate to the veins of the gastrointestinal tract
and liver.
⚫Eggs in the gut wall can lead to pain, blood in the
stool, and diarrhea (especially in children).
⚫Severe disease can lead to narrowing of the colon
or rectum
⚫Eggs also migrate to the liver leading to fibrosis in
4 to 8 percent of people with chronic infection,
mainly those with long term heavy infection.

23. Central Nervous system disease
⚫Central nervous system lesions occur occasionally.
⚫Cerebral granulomatous disease may be caused by
S. japonicum eggs in the brain.
⚫Communities in China affected by S. japonicum
have been found to have rates of seizures eight
times higher than baseline.
⚫Similarly, granulomatous lesions from S. mansoni
and
S. haematobium eggs in the spinal cord can lead to
transverse myelitis with flaccid paraplegia.

24. FILARIASIS:
⚫Elephantiasis affects mainly the lower extremities,
while the ears, mucous membranes, and
amputation stumps are affected less frequently
⚫Wuchereria bancrofti can affect the legs, arms,
vulva, breasts, and scrotum (causing hydrocele
formation), while Brugia timori rarely affects the
genitals.
⚫Those who develop the chronic stages of
elephantiasis are usually amicrofilaraemic, and
often have adverse immunological reactions to the
microfilariae, as well as the adult worms.

25. ⚫The list of signs and symptoms mentioned in
various sources for Lymphatic Filariasis includes
the 31 symptoms listed below: (major)
⚫Swollen lymph nodes ,Lymphedema ,Swollen
armpit lymph nodes ,Swollen groin lymph nodes
,Arm swelling ,Breast swelling ,Leg swelling ,Male
genital swelling ,Elephantiasis
,Lymphangitis ,Fever ,Aches ,Pain ,Epididymitis
,Orchitis
,Eosinophilia ,Hydrocele ,Chyluria , Thickened
skin

26. ASCARIASIS:
⚫Most people who are infected with only a small
number of
worms have no symptoms.
⚫Clinical features depend on the affected body site
⚫Migrating larva:
⚫As larval stages travel through the body, they may
cause visceral damage, peritonitis and
inflammation, enlargement of the liver or spleen,
and an inflammation of the lungs.
⚫ Pulmonary manifestations take place during
larval migration and may present as Loeffler's
syndrome, a transient respiratory illness associated
with blood eosinophilia and pulmonary infiltrates
with radiographic shadowing

27. ⚫Intestinal blockage:
⚫The worms can occasionally cause intestinal
blockage when large numbers get tangled
into a bolus or they may migrate from the
small intestine, which may require surgery.
⚫More than 796 A. lumbricoides worms
weighing up to 550 g [19 ounces] were
recovered at autopsy from a 2-year-old
South African girl. The worms had caused
torsion and gangrene of the ileum, which
was interpreted as the cause of death

28. Bowel obstruction:
⚫Bowel obstruction may occur in up to 0.2 per
1000 per year.
⚫Sometimes the worm blocks the Ampulla of
Vater or goes into the main pancreatic duct
resulting in acute pancreatitis with raised
serum levels of amylase and lipase.
Allergies:
⚫Ascariasis may result in allergies to shrimp
and dustmites due to the shared antigen,
tropomyosin; this has not been confirmed in
the laboratory

29. Malnutrition:
⚫The worms in the intestine may cause
malabsorption and anorexia which contribute to
malnutrition.The malabsorption may be due to
a loss of brush border enzymes, erosion and
flattening of the villi, and inflammation of the
lamina propria.
Others:
⚫Ascaris have an aversion to some general
anesthetics and may exit the body, sometimes
through the mouth.

30. Taeniasis/cysticercosis:
⚫Taeniasis is generally asymptomatic.
⚫ It is not fatal, although cysticercosis can
cause epilepsy and neurocysticercosis can be
fatal.]Heavy infection is indicated by intestinal
irritation, anaemia, and indigestion.
⚫ The eggs enter the intestine where they
develop into larvae. The larvae enter
bloodstream and invade host tissues. This clinical
condition, called cysticercosis, is the most
frequent and severe disease caused by any
tapeworm.

31. Taeniasis/cysticercosis:
⚫ It can lead to severe headaches, dizziness,
occasional seizures, dementia, hypertension,
lesions in the brain, blindness, tumor-like
growths, and low eosinophil levels. It is the
cause of major neurological problems, such as
hydrocephalus, paraplegy, meningitis,
convulsions, and even death.
⚫ It can cause antigen reaction that induce
allergic reaction.It is an also rare cause of ileus,
pancreatitis, cholecystitis, and cholangitis.

32. Echinococcosis:
⚫In the patients who are infected with E.
granulosus and therefore have cystic
echinococcosis, the disease develops into slow-
growing mass in the body.
⚫These slow-growing masses, are called
cysts.these cyst are also common in patients that
are infected with alveolar and polycystic
echinococcosis. The cysts found in those with
cystic echinococcosis are usually filled with a
clear fluid called hydatid fluid, are spherical,
and typically consist of one compartment and are
usually only found in one area of the body

33. Echinococcosis:
⚫If the patient is symptomatic, the symptoms will
depend largely on where the cysts are located. For
instance, if the patient has cysts in the lungs and is
symptomatic, they will have a cough, shortness of
breath and/or pain in the chest.
⚫ On the other hand, if the patient has cysts in
the liver and is symptomatic, they will suffer from
abdominal pain, abnormal abdominal tenderness,
hepatomegaly with an abdominal mass, jaundice,
fever and/or anaphylactic reaction.
⚫Some of the other symptoms includes: Bloody
sputum, cough, severe skin itching.

34. PREVENTION AND TREATMENT
Schistosomiasis:
•Prevention:
•Prevention is best accomplished by eliminating the
water-dwelling snails that are the natural reservoir
of the disease.
•Avoiding swimming or wading in freshwater
when you are in countries in which
schistosomiasis occurs. Swimming in the ocean
and in chlorinated swimming pools is safe.

35. PREVENTION AND TREATMENT
Schistosomiasis:
Prevention:
•Drinking safe water. Although schistosomiasis is not
transmitted by swallowing contaminated water, if your
mouth or lips come in contact with water containing the
parasites, you could become infected.
•Water used for bathing should be brought to a rolling boil
for 1 minute to kill any cercariae, and then cooled before
bathing to avoid scalding. Water held in a storage tank for
at least 1 - 2 days should be safe for bathing.

36. Treatment:
⚫Schistosomiasis is treatable by taking by
mouth a single dose of the drug praziquantel
annually.
⚫Other possible treatments include a
combination of praziquantel with
metrifonate, artesunate, or mefloquine
⚫Another agent, mefloquine, which has
previously been used to treat and prevent
malaria, was recognised in 2008– 2009 to be
effective against schistosoma

37. Filariasis:
Prevention:
⚫Avoidance of mosquito bites through personal protection
measures or community-level vector control is the best option to
prevent lymphatic filariasis.
⚫Periodic examination of blood for infection and initiation of
recommended treatment are also likely to prevent clinical
manifestations.
⚫To eliminate lymphatic filariasis (LF) as a public health
problem we must stop the spread of infection. Levels of worm
larvae (microfilaria) in the blood of infected persons must be
reduced so that mosquitoes cannot transmit the worms from one
human to another.

38. Treatmennt:
⚫ The strategy for interrupting transmission is
an annual single co-administration of two drugs
for at least five years. The two alternative
regimens are: single doses of albendazole
(400mg) plus Mectizan® (150-200 mg/kg/body
wt) or single doses of albendazole (400mg) plus
DEC (6mg/kg/body wt).
⚫DEC, developed over 50 years ago, is an
inexpensive and effective anti-filarial drug
which is used to treat LF in many countries.
DEC is available in tablet form and in a fortified
salt formulation for daily intake at meal times.

39. Treatmennt:
⚫Mectizan® (generic name: ivermectin) is an
oral anti-parasitic drug, discovered and
developed by Merck & Co. Inc. which is
effective against both LF and onchocerciasis.
Mectizan® is provided free of charge by Merck
& Co. Inc. for the treatment of onchocerciasis in
all endemic countries and for LF in African
countries where onchocerciasis and LF co-exist.
⚫Albendazole, donated by GlaxoSmithKline for
LF prevention, is a well-established anti-
parasitic treatment, given to an estimated 500-
800 million people, mostly children, for
intestinal infections over the past 20 years.

40. Ascariasis:
Prevention:
⚫The best way to prevent ascariasis is to always:
⚫Avoid ingesting soil that may be contaminated
with human feces, including where human fecal
matter ("night soil") or wastewater is used to
fertilize crops.
⚫Washing hands with soap and warm water
before handling food.

41. Ascariasis:
Prevention:
⚫Wash, peel, or cook all raw vegetables and fruits
before eating, particularly those that have been grown
in soil that has been fertilized with manure.
⚫By-Not defecating outdoors,effective sewage disposal
systems
⚫In areas where more than 20% of the population is
affected treating everyone is recommended. This has a
cost of about 2 to 3 cents per person per treatment. This
is known as mass drug administration and is often
carried out among school-age children.

42. Treatment:
⚫Albendazole 400 mg one dose orally is the drug of
choice. Ascariasis commonly coexists with whipworm
infection, which appears to be more susceptible to
albendazole than to mebendazole. Albendazole is not
recommended during pregnancy; pyrantel pamoate is
the drug of choice in these cases.
⚫Alternative therapy is mebendazole (100 mg bid for 3
d or 500 mg as a single dose). Mebendazole is not
recommended during pregnancy; pyrantel pamoate is
the drug of choice in these cases.
⚫Paralyzing vermifuges (eg, pyrantel pamoate,
piperazine, ivermectin) should be avoided in patients
with complete or partial intestinal obstruction since the
paralyzed worms may necessitate or further complicate
surgery.

43. Treatment:
⚫Vitamin A supplementation improved growth
development of children in Zaire; de worming did not
improve growth development in this study.
⚫Drug therapy affects only adult worms. If the patient
lives in an endemic area or has recently relocated, he or
she may still be carrying larvae that are not yet
susceptible. Such patients should be re-evaluated in 3
months and retreated if stool ova persist. In endemic
areas, reinfection rates approach 80% within 6 months.
⚫Nitazoxanide, a drug used primarily for protozoal
infection, was shown to have 89% clinical efficacy for
the treatment of ascariasis in rural Mexico and may
offer a future alternative to other medications