Parasitic infections affecting central nervous system

1. PARASITIC NEURO
INFECTIONS
PRESENTED BY:
MISS. SHWETA SHARMA
M.SC. NURSING
2nd YEAR
AIIMS JODHPUR

2. CASE
• May, a 4-year old female, is fond of playing. She and her playmates play
anywhere they could reach, with anything they could find. When May arrives
home, she immediately reaches for the snacks on the table without washing
her hands. Weeks after, her mother noticed that May keeps on scratching
her anal area, especially at night. She brought May to the community health
center, where the community health nurse performed a test she called the
scotch tape swab test. When the doctor arrived, May and her mother were
told that May has enterobiasis or pinworm infection.
31-10-2020 2

3. INTRODUCTION
• Parasites are a diverse group of organisms that can
be broadly classified into single-celled organisms
(i.e. protozoa) or multicellular helminths.
• Parasitic diseases of the central nervous system are
associated with high mortality and morbidity. The
burden of these diseases is amplified as survivors
are often left with neurologic symptoms affecting
mobility, sensory organs, and cognitive functions,
as well as seizures/epilepsy.
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4. • These diseases lead to suffering by
causing lifelong disabilities, reducing
economic productivity, and causing
social stigma. The complexity of parasitic
life cycles and geographic specificities,
as well as overlapping clinical
manifestations in the host reflecting the
diverse pathogenesis of parasites, can
present diagnostic challenges.31-10-2020 4

5. PARASITIC INFECTIONS OF THE
CENTRAL NERVOUS SYSTEM
• Neurocysticercosis
• Toxoplasmosis
• Echinococcosis (hydatidosis)
• Schistosomiasis
• Paragonimiasis
• Cerebral malaria- Severe falciparum malaria
• Toxocariasis
• Onchocerciasis
• American trypanosomiasis (Chagas disease)
• Human African trypanosomiasis (sleeping sickness)
• Angiostrongyliasis31-10-2020 5

6. Neurocysticercosis
• Result of accidental ingestion of eggs of
Taenia solium (i.e., pork tapeworm), usually
due to contamination of food by people with
taeniasis.
• In developing countries, neurocysticercosis
is the most common parasitic disease of the
nervous system and is the main cause of
acquired epilepsy.
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7. Epidemiology
•NCC predominantly affects adults in their third and
fourth decade of life, and is relatively uncommon in
children and the elderly. Most paediatric patients
have a single transitional cyst that resolves
spontaneously over a few months.
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8. Causes
•Eating undercooked pork from a pig with
the infection
•Consuming water that contains the parasite
•Having poor hygiene
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9. 31-10-2020 9

10. Clinical manifestations
• The clinical manifestations of NCC are
heterogeneous and depend mainly on the
localization of cysts and immune response by the
host.
• Seizures, headache, focal deficits and cognitive
abnormalities are the most frequent
manifestations of cysts in the brain parenchyma.
Extra parenchymal disease occurs in about one-
third of patients with NCC (life-threatening).
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11. • Acute hydrocephalus related to intraventricular
cysts, or chronic hydrocephalus because of
arachnoiditis or ependymitis.
• Spinal cord cysticercosis - rare - nerve root pain or
spinal cord compression syndromes, according to
the level of the lesion.
• Massive infection of striated muscles can cause
generalized weakness associated with muscle
pseudohypertrophy.
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12. Medical management
• Albendazole with corticosteroids
• Praziquantel (alternative to albendazole) with
corticosteroids
• Combined albendazole/praziquantel with
corticosteroids if >2 active parenchymal cysts
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13. Toxoplasmosis
• Toxoplasmosis is a disease that results
from infection with the Toxoplasma gondii
parasite, one of the world's most common
parasites. Infection usually occurs by
eating undercooked contaminated meat,
exposure from infected cat faeces, or
mother-to-child transmission during
pregnancy.31-10-2020 13

14. Epidemiology
• Globally, 1,90,100 annual cases of congenital toxoplasmosis have
been reported, leading to 1.20 million DALYs (Disability adjusted
life years) and 1.5 cases of congenital toxoplasmosis per 1000 live
births.
• In India, 56,737-176,882 children are born with a possible risk of
congenital toxoplasmosis every year. Seroprevalence of 22% in
pregnant women was reported.
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15. Risk factors
•HIV/AIDS
•Chemotherapy
•Steroids or other
immunosuppressant drugs
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16. Causes
Toxoplasma gondii (T. gondii) is a single-celled parasitic organism that can infect
most animals and birds. Because T. gondii infectious organisms are excreted only in
cat faeces, wild and domestic cats are the parasite's ultimate host. One can become
infected if he/she:
• Come into contact with cat faeces that contain the parasite.
• Eat or drink contaminated food or water.
• Use contaminated knives, cutting boards or other utensils.
• Eat unwashed fruits and vegetables.
• Receive an infected organ transplant or transfused blood.
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17. 31-10-2020 17

18. Pathophysiology
• After ingestion of the organism, Toxoplasma gondii cysts may develop in any tissue,
but most commonly develop in the brain, retina, skeletal muscle and cardiac
muscle. Rupture of the cysts releases the free tachyzoite, which causes acute
illness.
• Fever, rash, lymphadenopathy and eye disturbances are typical in early stages.
When lesions are in the CNS of immunocompromised patients, fever, headaches,
confusion and seizures are common, as well as ocular disease (retinochoroiditis);
however, many infections are subclinical, and 20% of HIV-infected patients with
toxoplasmosis develop encephalitis.
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19. The disease may also be transmitted
trans-placentally and have devastating
effects on the fetal brain because
maternal antibodies passed to the child
will be limited by the blood–brain
barrier. Seizures, microcephaly and
chorioretinitis have been noted in most
of these cases.
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20. Symptoms
• Body aches
• Swollen lymph nodes
• Headache
• Fever
• Fatigue
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21. In people with weakened immune systems:
•Headache
•Confusion
•Poor coordination
•Seizures
•Lung problems that may resemble tuberculosis or
Pneumocystis jiroveci pneumonia, a common opportunistic
infection that occurs in people with AIDS
•Blurred vision caused by severe inflammation of your retina
(ocular toxoplasmosis)
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22. Medical management
•Sulfadiazine + pyrimethamine with leucovorin
•Clindamycin (or atovaquone) + pyrimethamine
with leucovorin (alternative)
•Trimethoprim-sulfamethoxazole (alternative)
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23. Complications
• Eye infections. Untreated, these infections can
lead to blindness.
• Seizures and life-threatening illnesses such as
encephalitis — a serious brain infection.
• Children with congenital toxoplasmosis may
develop disabling complications, including
hearing loss, mental disability and blindness.
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24. Prevention
• Wear gloves when gardening or handling soil. Wear gloves
whenever working outdoors and washing hands thoroughly with
soap and water afterward.
• Don't eat raw or undercooked meat. Meat, especially lamb, pork
and beef, can harbour toxoplasma organisms.
• Wash kitchen utensils thoroughly. Wash hands after handling raw
meat.
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25. • Wash all fruits and vegetables. Remove
peels when possible, but only after
washing.
• Don't drink unpasteurized milk.
Unpasteurized milk and other dairy
products may contain toxoplasma
parasites.
• Cover children's sandboxes to keep cats
from using it as a litter box.
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26. For cat lovers
•Keep cat healthy. Keep cat indoors and feed it dry or canned cat food, not raw
meat.
•Avoid stray cats or kittens. Most cats don't show signs of T. gondii infection, and
although they can be tested for toxoplasmosis, it may take up to a month to get
the results.
•Have someone else clean cat's litter box. If that's not possible, wear gloves and a
face mask to change the litter. Then wash hands well. Change the litter daily so
that excreted cysts don't have time to become infectious.
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27. 31-10-2020 27

28. Echinococcosis (hydatidosis)
• Echinococcosis is a parasitic disease of tapeworms of the
Echinococcus type. The parasites Echinococcus granulosus
and Echinococcus multilocularis causing cystic
echinococcosis and alveolar echinococcosis, respectively,
belong to the same genus; however, these pathologies are
entirely different entities in terms of clinical manifestations,
course of disease and prognosis.31-10-2020 28

29. 31-10-2020 29

30. Epidemiology
• In regions where cystic echinococcosis is endemic,
incidence rates in humans can exceed 50 per 100 000
person-years.
• More than 1 million people are affected with
echinococcosis at any one time.
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31. Cause
• The worm has a life cycle that requires definitive hosts and intermediate
hosts. Definitive hosts are normally carnivores such as dogs, while
intermediate hosts are usually herbivores such as sheep and cattle.
• Humans function as accidental hosts, because they are usually a dead
end for the parasitic infection cycle. Humans are infected through
ingestion of parasite eggs in contaminated food, water or soil, or after
direct contact with animal hosts.
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32. Pathophysiology
• The infection may be primary or secondary to the spontaneous or
traumatic rupture of a primary cerebral cyst or because of
embolization of cardiac cysts. Cysts may remain asymptomatic
until they are large enough to cause a mass effect.
• Cerebral lesions occur in 1–4% of individuals with cystic
echinococcosis, with nonspecific clinical findings related to those
of space occupying lesions, increased intracranial pressure and
seizure activity.31-10-2020 32

33. Clinical manifestations
Cystic echinococcosis / hydatid disease
•Liver- abdominal pain, nausea and vomiting
•Lung - chronic cough, chest pain and shortness of
breath.
•Other signs depend on the location of the hydatid
cysts and the pressure exerted on the surrounding
tissues.
•Anorexia, weight loss and weakness31-10-2020 33

34. Alveolar echinococcosis
• Characterized by an asymptomatic incubation period of 5–15 years
and the slow development of a primary tumour-like lesion which is
usually located in the liver.
• Weight loss, abdominal pain, general malaise and signs of hepatic
failure.
• Larval metastases may spread either to organs adjacent to the liver
(for example, the spleen) or distant locations (such as the lungs, or
the brain) following dissemination of the parasite via the blood and
lymphatic system.
• If left untreated, alveolar echinococcosis is progressive and fatal.
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35. Medical management
• Albendazole or mebendazole (alone or with surgery)
Prevention
• Prevent dogs from feeding on the carcasses of infected sheep.
• Control stray dog populations.
• Restrict home slaughter of sheep and other livestock.
• Do not consume any food or water that may have been contaminated by fecal
matter from dogs.
• Wash hands with soap and warm water after handling dogs, and before
handling food.
• Teach children the importance of washing hands to prevent infection.
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36. Schistosomiasis
•Schistosomiasis, also known as
snail fever and bilharzia, is a
disease caused by parasitic
flatworms called
schistosomes.
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37. Epidemiology
• Schistosomiasis is prevalent in tropical and subtropical
areas, especially in poor communities without access to
safe drinking water and adequate sanitation.
• It is estimated that at least 90% of those requiring
treatment for schistosomiasis live in Africa. It affects about
200 million people worldwide.
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38. Cause
• People are infected during routine
agricultural, domestic, occupational, and
recreational activities, which expose them to
infested water.
• Lack of hygiene and certain play habits of
school-aged children such as swimming or
fishing in infested water make them
especially vulnerable to infection.
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39. Infection and transmission
• People become infected when larval forms of
the parasite – released by freshwater snails –
penetrate the skin during contact with
infested water.
• Transmission occurs when people suffering
from schistosomiasis contaminate freshwater
sources with their excreta containing parasite
eggs, which hatch in water.
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40. • In the body, the larvae develop into adult schistosomes. Adult
worms live in the blood vessels where the females release
eggs.
• Some of the eggs are passed out of the body in the faeces or
urine to continue the parasite’s lifecycle. Others become
trapped in body tissues, causing immune reactions and
progressive damage to organs.
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41. 5 Egg morphology of Schistosoma
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42. Symptoms
• Intestinal - abdominal pain, diarrhoea, and
blood in the stool.
• Liver enlargement, ascites and portal
hypertension and spleenomegaly.
• The classic sign of urogenital
schistosomiasis is haematuria (blood in
urine).
• Fibrosis of the bladder and ureter, and
kidney damage are sometimes diagnosed in
advanced cases. Bladder cancer is another
possible complication in the later stages.
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43. • In women, urogenital schistosomiasis may present with genital lesions,
vaginal bleeding, pain during sexual intercourse, and nodules in the vulva.
• In men, urogenital schistosomiasis can induce pathology of the seminal
vesicles, prostate, and other organs.
• Infertility
• Children - anaemia, stunting, reduced ability to learn, although the effects
are usually reversible with treatment.
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44. 31-10-2020 44

45. Medical management
Praziquantel (after starting corticosteroid treatment)
Prevention and control
• Large-scale treatment of at-risk population groups
• Access to safe water, improved sanitation, hygiene education, and
snail control.
• The WHO strategy for schistosomiasis control focuses on reducing
disease through periodic, targeted treatment with praziquantel
through the large-scale treatment (preventive chemotherapy) of
affected populations.
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46. Paragonimiasis
•Paragonimiasis is an infection
with parasitic worms.
Paragonimiasis can cause illness
resembling pneumonia or
stomach flu. The infection can
last for years.
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47. Epidemiology
• An estimated 293 million people are at risk of paragonimiasis
worldwide and it has been reported that about 23 million people
in 48 countries are infected.
• In India, human pulmonary paragonimiasis is emerging as an
important public health disease in north-eastern (NE) region.
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48. Causes
• Paragonimiasis is caused by
infection with a flatworm, also
called a fluke or lung fluke because it
commonly infects the lungs. Usually,
infection comes after eating
undercooked crab or crayfish that
carry immature flukes.
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49. Pathophysiology
• Once swallowed by a person, the worms
mature and grow inside the body. Over
months, the worms spread through the
intestines and abdomen. They penetrate
the diaphragm muscle to enter the lungs.
Once inside the lungs, the worms lay
eggs and can survive for years, causing
chronic paragonimiasis.31-10-2020 49

50. Symptoms
• Gastro-intestinal symptoms-
Fever and malaise
Diarrhoea
Abdominal pain
Nausea and vomiting
Itching and hives
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51. • Respiratory symptoms-
Cough
Shortness of breath
Chest pain (made worse by deep breathing or
coughing)
Haemoptysis
• Neurological symptoms-
Headache
Fever
Vomiting
Double vision
Seizures
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52. Medical management
•Praziquantel
•Triclabendazole
•Anti-seizure medications (for brain involvement)
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53. Cerebral malaria- Severe falciparum
malaria
• Caused by Plasmodium falciparum and may
result in an acute encephalopathy (with
febrile and acute seizures), which may be
fatal or lead to polymorphic neurological
sequelae.
• Caused if parasite-filled blood cells block
small blood vessels to brain and swelling of
brain or brain damage may occur.
• Cerebral malaria may cause seizures and
coma.
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54. Epidemiology
• According to the World Malaria Report 2017, in the year 2016,
more than half of the population (698 million) was at risk of
malaria.
• According to the Report, India accounted for 6% of all malaria
cases in the world, 6% of the deaths, and 51% of the global P. vivax
cases. The Report estimates the total cases in India at 1.31 million
(0.94-1.83 million) and deaths at 23990 (1600-46500).
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55. Pathophysiology
• Pathogenesis of cerebral malaria is due to damaged
vascular endothelium by parasite sequestration,
inflammatory cytokine production and vascular
leakage.
• The basic underlying defect seems to be clogging of
the cerebral microcirculation by the parasitized red
cells as a result of increased cytoadherent
properties due to which the parasites sequester in
these deeper blood vessels.
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56. • Also, rosetting of both healthy and infected red
cells further impairs healthy circulation. This
results in hypoxia and brain ischemia as depicted
by increased lactate and alanine concentrations
along with decreased aspartate and adenosine
triphosphate levels.
• The levels of the biomarkers’ histidine-rich
protein II, angiopoietin-Tie-2 system and plasma
osteoprotegrin serve as diagnostic and
prognostic markers.
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57. Symptoms
• Fever and rigors—the
malarial paroxysm
• Anaemia
• Jaundice
•Splenomegaly
• Hepatomegaly
• Abnormal posturing
• Nystagmus
•Conjugate gaze palsy
•Opisthotonos
•Seizures
•Hypoglycemia
•Metabolic acidosis
•Coma
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58. Medical management
•IV artesunate
•IV quinine dihydrochloride or quinidine
gluconate + doxycycline, tetracycline, or
clindamycin
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59. Toxocariasis
•Toxocariasis is an illness of
humans caused by larvae
(immature worms) of either the
dog roundworm (Toxocara canis),
the cat roundworm (Toxocara
cati) or the fox roundworm
(Toxocara canis).
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60. •Toxocariasis is often called visceral
larva migrans (VLM). The soil of parks
and playgrounds is commonly
contaminated with the eggs of T
canis, and infection may cause human
disease that involves the liver, heart,
lung, muscle, eye, and brain.
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61. Epidemiology
•In India, about 39,157 cases of Toxocara infection are
reported in humans each year. Almost 15% of the India
population is infected with Toxocara, a parasite of dogs
and cats that can be passed from animals to humans.
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62. Pathophysiology
• Transmission of Toxocara to humans is
usually through ingestion of infective
eggs. Eating undercooked rabbit,
chicken, or sheep can lead to infection;
encysted larvae in the meat can become
reactivated and migrate through a
human host, causing toxocariasis.
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63. There are three main syndromes associated with toxocariasis:
• Visceral larva migrans, which encompasses diseases associated
with major organs
• Covert toxocariasis, which is a milder version
• Ocular larva migrans, in which the pathological effects on the host
are restricted to the eye and the optic nerve.
CNS infestation is rare, but these patients may present with seizures,
eosinophilic meningitis, optic neuritis and meningomyelitis.
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64. Symptoms
•Visceral larva migrans –
Pallor
Fatigue
Weight loss
Anorexia
Fever
Headache
Skin rash
Cough
Asthma
Chest tightness
Increased irritability
Abdominal pain
Nausea and vomiting
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65. Covert toxocariasis –
Coughing
Fever
Abdominal pain
Headaches
Changes in behaviour and ability to
sleep
Wheezing
Hepatomegaly
Lymphadenitis
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66. Ocular larva migrans –
Loss of vision
Red eye
White pupil
Fixed pupil
Retinal fibrosis
Retinal detachment
Inflammation of the eye tissues, retinal granulomas, and
strabismus
Toxocara damage in the eye is permanent and can result in
blindness
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67. Medical management
• Asymptomatic patients and patients with mild
symptoms do not require anthelminthic therapy
because infection is usually self-limited.
• For patients with moderate to severe symptoms,
mebendazole 100 to 200 mg po bid for 5 days or
albendazole 400 mg po bid for 5 days is often used.
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68. Onchocerciasis
• Onchocerciasis, also known as river
blindness, is a disease caused by
infection with the parasitic worm
Onchocerca volvulus.
• It is the second-most common cause of
blindness due to infection, after
trachoma.31-10-2020 68

69. Epidemiology
• About 21 million people were infected with this parasite in 2017;
about 1.2 million of those had vision loss. As of 2017, about 99% of
onchocerciasis cases occurred in Africa.
• It is currently relatively common in 31 African countries, Yemen, and
isolated regions of South America.
• Over 85 million people live in endemic areas, and half of these reside
in Nigeria. Another 120 million people are at risk for contracting the
disease.
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70. Pathophysiology
• The parasite worm is spread by the bites of a black fly of the Simulium
type. Usually, many bites are required before infection occurs. These
flies live near rivers, hence the common name of the disease.
• Once inside a person, the worms create larvae that make their way out
to the skin, where they can infect the next black fly that bites the
person.
• The severity of illness is directly proportional to the number of infected
microfilariae and the power of the resultant inflammatory response.
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71. Symptoms
• Severe itching
• Bumps under the skin
• Blindness
• Nodding syndrome- an epileptic
encephalopathy characterized by
nodding of the head, affecting mainly
children in Africa.
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72. • Mazzotti reaction- Complex symptom seen in
patients after undergoing treatment of
onchocerciasis with the medication
diethylcarbamazine (DEC).
• Mazzotti reactions can be life-threatening, and
are characterized by fever, urticaria, swollen and
tender lymph nodes, tachycardia, hypotension,
arthralgias, oedema, and abdominal pain that
occur within seven days of treatment of
microfilariasis.
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73. Medical management
•Ivermectin
•Doxycycline
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74. American trypanosomiasis (Chagas
disease)
•Chagas disease, also known as
American trypanosomiasis, is a
potentially life-threatening illness
caused by the protozoan parasite
Trypanosoma cruzi (T. cruzi).
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75. Epidemiology
• About 6 million to 7 million people worldwide, mostly
in Latin America, are estimated to be infected with
Trypanosoma cruzi, the parasite that causes Chagas
disease.
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76. Pathophysiology
• The main route of transmission (vector-borne transmission) has
occurred in Latin America through the insect called triatomine
bug, which can carry the Trypanosoma cruzi.
• Other routes of transmission include: oral (food-borne)
transmission, blood/blood products transfusion, mother-to-child
(congenital) and organ transplantation transmissions or even
laboratory accident transmission.
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77. • Normally they hide during the day and become active at night
when they feed on mammalian blood, including human blood.
• They usually bite an exposed area of skin such as the face (hence
its common name ‘kissing bug’), and the bug defecates or urinates
close to the bite.
• The parasites enter the body when the person instinctively smears
the bug faeces or urine into the bite, the eyes, the mouth, or into
any skin break.
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78. Symptoms
• Initial acute phase - 2 months.
• During the acute phase, a high number of parasites circulate in the blood but
in most cases, symptoms are absent or mild and unspecific.
• In less than 50% of people bitten by a triatomine bug, characteristic first
visible signs can be a skin lesion or a purplish swelling of the lids of one eye.
• Additionally, they can present fever, headache, enlarged lymph glands,
pallor, muscle pain, difficulty in breathing, swelling, and abdominal or chest
pain.
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79. • During the chronic phase, the parasites are hidden mainly in the
heart and digestive muscles. Up to 30% of patients suffer from
cardiac disorders and up to 10% suffer from digestive (typically
enlargement of the oesophagus or colon), neurological or mixed
alterations.
• In later years the infection can lead to sudden death due to cardiac
arrhythmias or progressive heart failure caused by the destruction
of the heart muscle and its nervous system.
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80. Medical management
• Benznidazole
• Nifurtimox
Both medicines are nearly 100% effective in curing the disease if
given soon after infection at the onset of the acute phase including
the cases of congenital transmission. The efficacy of both
diminishes, however, the longer a person has been infected and the
adverse reactions are more frequent at older age.
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81. Prevention
• Vector control
• Blood screening- to prevent infection through
transfusion and organ transplantation.
• Detection and treatment of girls and women of
child-bearing with infection is essential, together
with the screening of new-born’s and siblings of
infected mothers without previous antiparasitic
treatment.
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82. • Spraying of houses and surrounding areas with
residual insecticides.
• House improvements and house cleanliness to
prevent vector infestation.
• Personal preventive measures such as bed nets.
• Good hygiene practices in food preparation,
transportation, storage and consumption.
• Testing of organ, tissue or cell donors and receivers.
31-10-2020 82

83. Human African trypanosomiasis
(sleeping sickness)
•African Trypanosomiasis, also
known as “sleeping sickness”, is
caused by microscopic parasites
of the species Trypanosoma
brucei.
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84. Epidemiology
• Sustained control efforts have reduced the number of
new cases. In 2009 the number reported dropped
below 10,000 for the first time in 50 years, and in
2018 there were 977 cases recorded. (Africa)
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85. Pathophysiology
• It is transmitted by the tsetse fly (Glossina species),
which is found only in sub-Saharan Africa.
• Two morphologically indistinguishable subspecies of
the parasite cause distinct disease patterns in
humans: T. b. gambiense causes a slowly progressing
African trypanosomiasis in western and central
Africa and T. b. rhodesiense causes a more acute
African trypanosomiasis in eastern and southern
Africa.
31-10-2020 85

86. Infection and symptoms
The disease is mostly transmitted through the bite of an infected
tsetse fly but there are other ways in which people are infected:
• Mother-to-child infection
• Mechanical transmission through other blood-sucking insects is
possible, however, it is difficult to assess its epidemiological
impact.
• Accidental infections in laboratories due to pricks with
contaminated needles.
• Transmission of the parasite through sexual contact.
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87. • First stage- the trypanosomes multiply in subcutaneous tissues, blood and
lymph. This is also called haemo-lymphatic stage, which entails bouts of fever,
headaches, enlarged lymph nodes, joint pains and itching.
• Second stage- the parasites cross the blood-brain barrier to infect the central
nervous system. This is known as the neurological or meningo-encephalic
stage. In general, this is when more obvious signs and symptoms of the disease
appear: changes of behaviour, confusion, sensory disturbances and poor
coordination. Disturbance of the sleep cycle, which gives the disease its name,
is an important feature. Without treatment, sleeping sickness is considered
fatal.31-10-2020 87

88. Medical management
Drugs used in the treatment of first stage:
• Pentamidine
• Suramin
Drugs used in the treatment of second stage:
• Melarsoprol
• Eflornithine
• Nifurtimox
Drugs used in the treatment of both stages:
• Fexinidazole
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89. Angiostrongyliasis
• Also known as the rat lungworm, is a parasitic nematode (worm) that is
transmitted between rats and mollusks (such as slugs or snails) in its natural
life cycle.
• Other animals that become infected such as freshwater shrimp, land crabs,
frogs, and planarians of the genus Platydemus, are transport hosts that are not
required for reproduction of the parasite but might be able to transmit
infection to humans if eaten raw or undercooked.
• Humans are accidental hosts who do not transmit infection to others.
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91. Epidemiology
• Angiostrongylus cantonensis occurs widely in the
tropics. Most infections occur in Southeast Asia, but
small epidemics have been reported more recently
from the Caribbean and elsewhere.
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92. Transmission
Transmission occurs by ingestion of third-stage larvae in
raw or undercooked snails or slugs. It can also result
from ingestion of raw or undercooked transport hosts
such as freshwater shrimp or prawns, crabs and frogs.
Nature of the disease
Ingested larvae can migrate to the central nervous
system and cause eosinophilic meningitis.
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93. Symptoms
• Headache
• Nausea and vomiting
• Neck stiffness
• Fever
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94. Medical management
Corticosteroids and symptomatic treatment only
Prevention
Food and water hygiene; in particular avoid eating
raw/undercooked snails and slugs, or raw produce such as
lettuce can prevent the disease. No vaccine is available.
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95. DIAGNOSTIC EVALUATION FOR
PARASITIC DISEASES
A faecal (stool) exam, also called an ova and parasite test (O&P)
• This test is used to find ova (eggs) or parasites that cause
diarrhoea, loose or watery stools, cramping, flatulence (gas) and
other abdominal illness.
• CDC recommends that three or more stool samples, collected on
separate days, be examined.
• Instruct the patient to put his stool specimens into special
containers with preservative fluid.
• Specimens not collected in a preservative fluid should be
refrigerated, but not frozen, until delivered to the lab or the health
care provider’s office.
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97. Endoscopy/Colonoscopy
• Used to find parasites that cause diarrhea, loose or watery stools,
cramping, flatulence (gas) and other abdominal illness.
• Used when stool exams do not reveal the cause of diarrhea.
• This test looks for the parasite or other abnormalities that may be
causing signs and symptoms.
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99. Blood tests
• Serology- To look for antibodies or
for parasite antigens
• Blood smear- To look for parasites.
By looking at a blood smear under a
microscope, parasitic diseases such
as filariasis, malaria, or babesiosis,
can be diagnosed.
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100. •X-ray, Magnetic Resonance
Imaging (MRI) scan,
Computerized Axial Tomography
scan (CAT) are used to look for
some parasitic diseases that may
cause lesions in the organs.
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101. NURSING MANAGEMENT
• Nursing care focuses on ongoing assessment of the neurologic
status, administering medications, assessing the response to
treatment, and providing supportive care.
• Ongoing neurologic assessment alerts the nurse to changes in ICP,
which may indicate a need for more aggressive intervention.
• The nurse also assesses and documents the responses to
medications.
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102. • Blood laboratory test results, specifically blood glucose and serum potassium
levels, need to be closely monitored when corticosteroids are prescribed.
• Patient safety is also a key nursing responsibility. Injury may result from
decreased level of consciousness and falls related to motor weakness or
seizures.
• The nurse must assess the family’s ability to express their distress at the
patient’s condition, cope with the patient’s illness and deficits, and obtain
support.
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104. Tobias Brummaier et al in 2019 reported a case of blind passenger: a rare case
of documented seroconversion in an Angiostrongylus cantonensis induced
eosinophilic meningitis in a traveller visiting friends and relatives. A 33-year old
woman with a travel history to rural north-eastern Thailand presented to an
emergency department in Switzerland with severe headache and vomiting.
Eosinophilic meningitis was confirmed as the cause of the symptoms; however,
serologic investigations failed to confirm an A. cantonensis infection on the
first evaluation. Nevertheless, empirical treatment with an anthelminthic and
steroid regimen led to a rapid alleviation of symptoms. Repeated serology
confirmed seroconversion 2 weeks after treatment initiation. Parasitic etiology
must be considered in returning travellers who present with symptoms
compatible with a central nervous system infection. A thorough medical
history, including types of food consumed, is paramount and can often
suggest differential diagnosis. Neuroangiostrongyliasis is rare and might be
missed if serology does not cover possible seroconversion.
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105. CONCLUSION
• Parasitic diseases of the central nervous system are associated with high mortality and
morbidity, especially in resource-limited settings. The burden of these diseases is
amplified as survivors are often left with neurologic sequelae affecting mobility,
sensory organs, and cognitive functions, as well as seizures/epilepsy.
• The complexity of parasitic life cycles and geographic specificities, as well as
overlapping clinical manifestations in the host reflecting the diverse pathogenesis of
parasites, can present diagnostic challenges. Hence an overview of these parasitic
diseases clinical aspects, diagnosis, therapeutic strategies and recent milestones, and
aspects related to prevention and control were discussed.
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