An overview of Helmintic infections

1. ANTHELMINTICS
By Kennedy Mantanyani RN, BSc Public Health

2. Outline
 Introduction
 Species of Schitosoma
 Lifecycle of helminths involved in schistosomiasis and neurocysticercosis
 The drug of choice and dosage duration
 Adjuvants used in treatment of schistosomiasis and neurocysticercosis
 Role of steroids and when should steroids be introduced
 Treatment for parenchyma and extra-parenchymal neurocysticercosis
 Preventive measures in management of Schistosomiasis and neurocysticercosis

3. Introduction - Schistosomiasis
 Schistosomiasis is a parasitic disease caused by schistosoma worm and is
characterized by blood in urine, itchy skin rash and fever.
 Schistosomas can be found in fresh water and people become nfected by
coming into contact with contaminated water with the parasitic larvae which
penetrates the skin and into the bloodstream
 Once in the blood stream it goes to the liver and intestines.
 Schistosomiasis can lead to chronic health problems such as anaemia, liver
and spleen damage. It can also affect other organs like the bladder, kidney
and also the brain causing neurological symptoms.

4. Introduction - Neurocysticercosis
 Neurocysticercosis is a preventable parasitic infection caused by larval cysts
(sacs containing immature stage of a parasite) of the pork tape worm also
known as Taenia Solium. These larval cysts can infect various parts of the
body causing a condition known as cysticercosis, called neurocysticercosis
which can lead to seizures and headaches. If not treated the disease can lead
to Epilepsy as a complication.
 Neurocysticercosis affects the brain and can be fatal because it is a severe
disease.
 One can get infected by swallowing microscopic eggs passed in the feaces of a
person with intestinal pork tape worm (faecal-oral) . Additionally, one can
also be infected by ingesting contaminated food and water.

5. Species of Schitosoma
 Three main species of Schistosoma include;
 Schistosoma japonicum
 Schistosoma mansoni
 Schistosoma haematobium
 Other species may include:
 Schistosoma mekongi
 Schistosoma intercalatum
 Schistosoma guineensis

6. Life cycle of
Schistosomiasis

8. Life cycle of Schistosomiasis
 Schistosoma eggs are eliminated with feces or urine, depending on species.
 Under appropriate conditions the eggs hatch and release miracidia, which
swim and penetrate specific snail intermediate hosts.
 The stages in the snail include two generations of sporocysts and the
production of cercariae.
 Upon release from the snail, the infective cercariae swim, penetrate the skin
of the human host, and shed their forked tails, becoming schistosomulae.

9. Life cycle of Schistosomiasis cont.
 The schistosomulae migrate via venous circulation to lungs, then to the heart,
and then develop in the liver, exiting the liver via the portal vein system
when mature.
 Male and female adult worms copulate and reside in the mesenteric venules,
the location of which varies by species (with some exceptions).
 For instance, S. japonicum is more frequently found in the superior
mesenteric veins draining the small intestine, and S. mansoni occurs more
often in the inferior mesenteric veins draining the large intestine.
 However, both species can occupy either location and are capable of moving
between sites.
 S. intercalatum and S. guineensis also inhabit the inferior mesenteric plexus
but lower in the bowel than S. mansoni.

10. Life cycle of Schistosomiasis cont.
 S. haematobium most often inhabits in the vesicular and pelvic venous plexus
of the bladder, but it can also be found in the rectal venules.
 The females (size ranges from 7–28 mm, depending on species) deposit eggs in
the small venules of the portal and perivesical systems.
 The eggs are moved progressively toward the lumen of the intestine (S.
mansoni, S. japonicum, S. mekongi, S. intercalatum/guineensis) and of the
bladder and ureters (S. haematobium), and are eliminated with feces or
urine, respectively.

11. Life cycle of
neurocysticercosis

13. Life cycle of neurocysticercosis
 Cysticercosis is an infection of both humans and pigs with the larval stages of
the parasitic cestode, Taenia solium.
 This infection is caused by ingestion of eggs shed in the feces of a human
tapeworm carrier .
 These eggs are immediately infectious and do not require a developmental
period outside the host.
 Pigs and humans become infected by ingesting eggs or gravid proglottids.
 Humans are usually exposed to eggs by ingestion of food/water contaminated
with feces containing these eggs or proglottids or by person-to-person spread.

14.  Tapeworm carriers can also infect themselves through fecal-oral transmission
(e.g. caused by poor hand hygiene).
 Once eggs or proglottids are ingested, oncospheres hatch in the
intestine , invade the intestinal wall, enter the bloodstream, and migrate to
multiple tissues and organs where they mature into cysticerci over 60–70
days .
 Some cysticerci will migrate to the central nervous system, causing serious
sequelae (neurocysticercosis).

15. Drugs of choice

16. Anthelmintic drugs for schistosomiasis
 Praziquantel

17. Praziquantel
 Schistosoma haematobium worm infections | Schistosoma
 mansoni worm infections
 ▶ BY MOUTH
 ▶ Adult: 20 mg/kg, followed by 20 mg/kg after 4–6 hours
 Schistosoma japonicum worm infections
 ▶ BY MOUTH
 ▶ Adult: 20 mg/kg 3 times a day for 1 day

18. Mode of Action
 Praziquantel works by causing severe spasms and paralysis of the worms'
muscles. This paralysis is accompanied - and probably caused - by a rapid Ca
2+ influx inside the schistosome. Morphological alterations are another early
effect of praziquantel.

19. Side Effects
 Black, tarry stools.
 blistering, peeling, or loosening of the skin.
 bloody diarrhea.
 blurred or loss of vision.
 chest pain or discomfort.
 difficulty swallowing.
 difficulty with moving.
 disturbed color perception.

20. Anthelmintics used in neurocysticercosis
 Praziquantel and Albendazole

21. Praziquantel
 Tapeworm infections (Taenia solium)
 ▶ BY MOUTH
 ▶ Adult: 5–10 mg/kg for 1 dose, to be taken after a light
 breakfast
 Tapeworm infections (Hymenolepis nana)
 ▶ BY MOUTH
 ▶ Adult: 25 mg/kg for 1 dose, to be taken after a light
 breakfast

22. Albendazole
 Chronic Strongyloides infection
 ▶ BY MOUTH
 ▶ Adult: 400 mg twice daily for 3 days, dose may be
 repeated after 3 weeks if necessary
 Hydatid disease, in conjunction with surgery to reduce the
 risk of recurrence or as primary treatment in inoperable
 cases

23.  ▶ BY MOUTH
 ▶ Adult: (consult product literature)
 Hookworm infections
 ▶ BY MOUTH
 ▶ Adult: 400 mg for 1 dose

24. Mode of Action
 The principal mode of action for Albendazole is by its inhibitory effect on
tubulin polymerization which results in the loss of cytoplasmic microtubules in
the intestines of nematodes worms, ultimately causing energy depletion and
death of the organism.

25. Side effects
 sore throat, fever, chills, and other signs of infection.
 unusual bleeding or bruising.
 weakness.
 fatigue.
 pale skin.
 shortness of breath.
 rash.
 hives.

26. Adjuvants used in treatment of
schistosomiasis and neurocysticercosis
 Adjuvants
 A drug that used to increase the efficacy or potency of a certain drug.
 Adjuvant increases the action principle of the drugs absorption, mechanism of
action, metabolism or excretion of the primary drug.
 Adjuvants include;
 Aluminum phosphate
 Aluminium Potassium Sulphate
 Aluminum Hydroxide

27. Role of steroids and when should
steroids be introduced
 Corticosteroid are common used to control inflammation that occurs during
the natural evolution of disease and as a consequence of anthelmintic
treatment.
 They can be used when a person presents with signs of inflammation such as
fever, swelling, redness, and illness is severe especially in neurocysticercosis
where there is increased inflammation and
 The steroids that are commonly used include Prednisolone (30–60 mg/day) for
10 to 15 days is recommended if the diagnosis is secure and the symptoms are
severe or Dexamethasone 4.5 – 12mg/day.

28. Side effects of steroids
 Sleep problems
 Mood changes
 Indigestion
 Weight gain
 Decreased urine output
 Heart palpitations
 Blurred vision
 Anxiety
 Headache
 Diziness

29. Prevention of schistosomiasis
 Avoiding contact with contaminated water where schistosoma are present.
 Avoiding swimming or walking in freshwater sources where schistosoma are
present
 Practicing high levels of personal hygiene and sanitation in those areas where
schistosomiasis is endemic.
 Drinking clean and safe water must be encouraged
 Putting on gumboots when walking in contaminated water for protection to
prevent direct contact with the water.

30. Prevention of Neurocysticercosis
 Proper regular handwashing
 Treatment of people infected with intestinal tapeworms could reduce the
number of new infections
 Routine administration of Albendazole (every after six months) and
Praziquantel to people who are at high risk like those who eat too much pork
and under-five years children.

31. References
 Abba, K., Ramaratnam, S. and Ranganathan, L.N. (2010) Anthelmintics for people with
neurocysticercosis, The Cochrane database of systematic reviews. U.S. National Library of
Medicine. Available at:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6532590/#:~:text=There%20are%20two%20a
nthelmintics%20used,response%20to%20the%20destroyed%20parasites. (Accessed: April 3,
2023).
 BMJ Group (2017) BNF. London: BMJ Group and Pharmaceutical Press.
 CDC (2022) CDC - cysticercosis - biology, Centers for Disease Control and Prevention. Centers
for Disease Control and Prevention. Available at:
https://www.cdc.gov/parasites/cysticercosis/biology.html (Accessed: April 3, 2023).
 Shadab Hussain Ahmed, M.D. (2023) Schistosomiasis (Bilharzia) medication, Anthelmintics.
Medscape. Available at: https://emedicine.medscape.com/article/228392-
medication#:~:text=Medication%20Summary&text=Praziquantel%20and%20oxamniquine%20(no
%20longer,for%20all%20species%20of%20schistosomiasis. (Accessed: April 3, 2023).

32. Thank you for listening