Diseases_of_Public_Health_Significance_helminths (1).pdf

Lecture Objectives Introduction Classification of Helminths Roundworms: Ascariasis Roundworms: Trichuriasis Roundworms: To
Helminthic Infections
Yusuf Misau, PhD
Child Health And Mortality Prevention Surveillance Project
College of Medical Sciences
Abubakar Tafawa Balewa University Bauchi
June 2023
Yusuf Misau, PhD ATBU College of Medical Sciences

Lecture Outline
1 Lecture Objectives
2 Introduction
3 Classification of Helminths
4 Roundworms: Ascariasis
5 Roundworms: Trichuriasis
6 Roundworms: Toxocariasis
7 Roundworms: Dracunculiasis

Lecture Objectives
At the end of this course, students will be able to:
Describe global burden of helminthic infections
Describe different classes of helminths.
Describe how helminths diseases are spread.
List public health effects of helminths
Describe the control of helminths in the community.

Introduction
Helminths are a diverse group of parasitic worms that infect
over one billion people globally.
cause a variety of infections, ranging from mild to severe, and
are a significant cause of morbidity and mortality, particularly
in developing countries.
The global burden of helminthic infections is immense, with
some estimates suggesting that they cause more than 135,000
deaths annually.

Introduction
Commonest types of helminthic infections are soil-transmitted
helminths (STHs), eg: roundworms, whipworms, and
hookworms, which are transmitted through contaminated soil.
Another group are the schistosomes, found in freshwater snails
and cause schistosomiasis, a chronic disease that affects
millions of people in sub-Saharan Africa, South America, and
Asia.
Additionally, tapeworms and flukes can also cause significant
morbidity and mortality in humans.

Introduction
The burden of helminthic infections falls disproportionately on
the world’s poorest communities, where access to clean water
and sanitation is limited.
Children are particularly vulnerable to these infections, which
can cause malnutrition, growth retardation, cognitive
impairment, and decreased school performance. In addition to
the direct health effects, helminthic infections can also
contribute to poverty by reducing productivity and increasing
healthcare costs.

Introduction
Efforts to control and eliminate helminthic infections have
primarily focused on mass drug administration (MDA)
programs, which involve treating entire communities with
antihelminthic drugs.
While MDA has been successful in reducing the prevalence
and intensity of infection in some areas, there are concerns
about the emergence of drug resistance and the sustainability
of these programs in the long term.

Classification of Helminths
Helminths Classification
Classification Example
Nematodes Ascaris
Tricuriasis
Toxocariasis
Dracontiasis
Cestodes Taeniasis
Hydatid disease
Trematodes Facioliasis
Paragonimiasis

Roundworms: Ascariasis
Ascariasis is a parasitic disease caused by the roundworm
Ascaris lumbricoides, affects around 1 billion people worldwide.
Reservoir: The main reservoirs of A. lumbricoides are humans,
particularly those living in areas with poor sanitation and
hygiene practices. The eggs of the parasite are excreted in the
feces of infected individuals
Transmission: through ingestion of eggs, found in
contaminated soil, water, or food. The eggs hatch in the
small intestine, and the larvae migrate to the lungs before
being coughed up and swallowed again. The adult worms then
reside in the small intestine, where they can produce eggs and
perpetuate the cycle of infection.

Ascariasis
Host: A. lumbricoides can infect people of all ages, but it is
most common in children.
Risk factors: poor sanitation and hygiene, poverty, and living
in areas with a high prevalence of the disease. Symptoms of
ascariasis can range from mild gastrointestinal discomfort to
more severe complications such as bowel obstruction and
malnutrition.

Ascariasis: control
Individual: At the individual level, proper sanitation and
hygiene practices are crucial to preventing infection. This
includes regular handwashing, using latrines or toilets, and
avoiding the consumption of contaminated food or water.
Individuals who are infected should receive appropriate
medical treatment and follow-up care.

Ascariasis: control
Family: At the family level, education and awareness programs
can be implemented to promote good hygiene practices and
prevent the spread of infection. Families can also be
encouraged to seek medical treatment for infected members
and to participate in regular deworming campaigns.

Ascariasis: control
Community: At the community level, sanitation and hygiene
infrastructure should be improved to reduce the risk of
contamination. Safe water sources and appropriate waste
disposal facilities should be provided, and regular deworming
campaigns can be conducted to target high-risk populations.
Health education and awareness campaigns can also be
conducted to increase knowledge about the disease and
promote preventive behaviors.

Roundworms: Trichuriasis
Trichuriasis, also known as whipworm infection, is a parasitic
disease caused by the nematode Trichuris trichiura. It is
prevalent in tropical and subtropical regions, particularly in
areas with poor sanitation and hygiene.
Reservoir: The primary reservoir for T. trichiura is human
beings, particularly those living in areas with inadequate
sanitation and hygiene facilities. The eggs of the parasite are
excreted in the feces of infected individuals and can
contaminate soil, water, and food.

Transmission: The transmission of T. trichiura occurs through
the ingestion of infective eggs found in contaminated soil,
water, or food. Once ingested, the eggs hatch in the small
intestine, and the larvae migrate to the large intestine, where
they mature into adult worms. The adult worms then attach
to the intestinal wall and produce eggs, which are passed out
in the feces, perpetuating the cycle of infection.

Host: T. trichiura can infect individuals of all ages, but it is
most prevalent in children. The risk of infection is higher in
areas with poor sanitation and hygiene, and the infection can
lead to chronic diarrhea, malnutrition, anemia, and impaired
cognitive development.

Trichuriasis: control
Detection: lemon-shaped ova seen on direct smear of feaces.
In massive infection there is high eosinophilia (10-20%),
microcytic hypochromic anemia
Control involves mass drug treatment, improved sanitation
and personal hygiene

Roundworms: Toxocariasis
Toxocariasis is a parasitic disease caused by the roundworms
Toxocara canis and Toxocara cati, which are primarily found
in dogs and cats the main reservoirs.
Transmission: The transmission of toxocariasis occurs through
the ingestion of infective eggs found in contaminated soil,
water, or food.
Ingested eggs hatch in the small intestine, and the larvae can
migrate to various tissues and organs, causing damage and
inflammation. Humans can also become infected by direct
contact with infected animals or through the ingestion of
undercooked or raw meat from infected animals.

Roundworms: Toxocariasis
Host: Toxocariasis can affect individuals of all ages, but it is
most common in children. Risk factors for infection include
living in areas with high dog and cat populations, poor
hygiene practices, and a lack of awareness about the disease.
Detection: Biopsy, ELISA, IgM Level, eosinophilia.
Preventive measures: good sanitation and hygiene practices,
reduce exposure to contaminated soil and water, and treating
infected pets with appropriate antihelmintics eg piperazine .
Education and awareness campaigns

Roundworms: Dracunculiasis
Dracunculosis, also known as Guinea worm disease, is a
parasitic infection caused by the Guinea worm. The larvae of
the worm enter the body through contaminated water and
mature in the human host, causing painful blisters on the
skin. Treatment involves slowly extracting the worm from the
skin using a stick.

Roundworms: Dracunculiasis
Dracunculosis has been eradicated in most parts of the world
but is still endemic in some countries, mainly in sub-Saharan
Africa.
In 2020, only 27 cases of Guinea worm disease were reported
globally, a significant decrease from the 3.5 million cases
reported in 1986.
Despite this progress, dracunculosis remains a public health
concern.
The disease mainly affects impoverished populations with
limited access to clean water and sanitation facilities.
Eradication efforts involve water sanitation, health education,
and disease surveillance programs, which are essential for
achieving a world free of dracunculosis.

Dracunculiasis: Good news from Nigeria
According to the World Health Organization, Nigeria was
declared free of dracunculosis in 2013 after reporting zero
cases for over three years.
This achievement was the result of a concerted effort by the
Nigerian government and its partners to control the disease.
However, surveillance efforts to ensure that there are no
undetected cases of Guinea worm disease continue in Nigeria
and other countries to prevent the reemergence of the disease.

Home work
Read the life cycles of the parasitic agents of all the diseases
you have learned about in this lecture

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