1) The document discusses various parasitic diseases of the central nervous system including toxoplasmosis, amoebic infections, neurocysticercosis, nematodes, schistosomiasis, echinococcosis, trichenellosis, cerebral malaria, and human African trypanosomiasis. 2) Many of these parasites are transmitted through ingestion of contaminated food, water, or insects and can cause a range of neurological symptoms depending on the area of CNS infection including seizures, focal deficits, and mental status changes. 3) Diagnosis involves imaging, serology, and identification of the parasite in samples, while treatment consists of antiparasitic medications alongside steroids

1. NAME: DR SOLANKE ANDREW OLUSEGUN
TOPIC: PARASITIC DISEASE OF THE CENTRAL
NERVOUS SYSTEM (CNS)

2. • TOXOPLASMOSIS
Cerebral toxoplasmosis caused by Toxoplasma gondii was previously a rare disease.
Toxoplasma is found throughout the world in carnivorous, herbivorous and omnivorous
animals. The organism is found in meat as well as in the faeces of cats. Infection in man is
through accidental transfusion of blood from an infected donor or by eating food
contaminated with the faeces of cats, which are the primary hosts of this obligate
intracellular parasite. Infection can also be congenital. Once infected, cysts are formed in the
tissues, which remain asymptomatic. However, if the body's immunity is depressed, the cysts
flare up and could involve the brain as a multicentric disease. This multifocal pathology is
responsible for the generalized neurological manifestations such as headaches, personality
changes and confusional states, although focal symptoms may be encountered.
Toxoplasmosis should be considered in the differential diagnosis of CVA, posterior fossa
lesions, and seizures. In immunodeficient children, Toxoplasmosis may be difficult to
distinguish from cerebral lymphoma (Mitchell, 1999). Serology tests are unreliable. CT and
MRI of the brain may show multifocal low-density space occupying lesions that show ring
enhancement with contrast and are surrounded by edema. These must be differentiated
from other lesions such as multiple pyogenic or other abscesses, glioma and lymphoma.
Toxoplasmosis can cause headache, seizures, focal neurological deficits and mental status
changes.
The preferred treatment for toxoplasmosis includes pyrimethamine, leucovorin and
sulfadiazine. If there’s any concern for elevated intracranial pressure, then steroids should
also be used. As usual, it’s best to prevent the infection from ever occurring by avoiding
immunosuppression, and using prophylactic medication in those with compromised immune
systems. Due to prophylactic treatments and antiretroviral therapy

3. • AMOEBA
Fowler and Carter (1965) and Carter (1968), were the first to report CNS infection by free-living amoeba
(FLA). The offending pathogen was later shown to be Naegleria fowleri, which is the only species of
Naegleria that is pathogenic to man. It is a fulminant meningoencephalitis that kills the victim within 3-7
days. By 1997, only 179 cases had been reported and 81 of them were in the USA alone (Martinez &
Visvesvara, 1997). The FLA may also produce chronic granulomatous Amoebic Encephalitis lesions of the
CNS but these are due to Acanthamoeba.
Infections of Naegleria are usually from exposure to fresh or brackish water during swimming, diving and
bathing especially during warmer seasons. The infection is caused by trophozoites of Naegleria
penetrating the nasal mucosa and migrating via the olfactory nerves. FLA is found in the soil and fresh
water all over the world and is ubiquitous in nature although the disease is uncommon. N. fowleri
infection is endemic in Virginia and Florida in the USA, Czechoslovakia, Australia and New Zealand. Primary
amoebic meningoencephalitis occurs worldwide and major epidemics have occurred in USA, Europe,
Australia, Africa especially West and Central Africa, India, New Zealand, and South America (Duma 1972)
Acanthamoeba infects mostly people whose immunity is deficient or compromised. It has many species
that are pathogenic to man and of its two forms - trophozoite and cyst, only the former is invasive. It is
found in the nasopharynx of even normal people and it infects the CNS, skin, ear, eyes and the respiratory
passages. CNS infection may come from an extracerebral spread or like N. fowleri by invasion of the nasal
mucosa and olfactory nerves as the ingestion of the trophozoite is harmless. Acute amoebic
meningoencephalitis mimics purulent meningitis in its presentation, but in addition there is ageusia or
parosmia due to the involvement of the olfactory pathways. The CSF is cloudy, blood stained, has
increased neutrophils and red blood cells and low sugar. Amoebae are seen on microscopy. A CT scan of
the brain may show hemorrhagic necrosis. Granulomatous amoebic meningoencephalitis is a more chronic
illness, giving rise to focal brain signs and symptoms, which mimic brain, abscess. The resultant brain
edema may prove fatal due to uncal herniation. CSF is not diagnostic and amoebae are not seen as in the
acute illness. CT brain may reveal abscess and serology tests may be helpful in diagnosis. Naegleria
responds to amphotericin B, rifampicin, tetracycline, and minocycline. Acanthamoeba on the other hand,
does not respond to medical treatment hence surgical excision is the most effective therapy

4. • Entamoeba histolytica
This is an intestinal parasite that may become invasive causing hepatic or pulmonary
disease. It may spread via the blood from any of these sites to the brain where usually
multiple brain "abscess" is produced. However, these are false abscesses containing
necrotic brain tissue in the center surrounded by an area of congestion, degeneration,
lymphocytes, plasma cells and other mononuclear cells. Diagnosis is by CT scan, which
may reveal not only the brain lesions but also the liver, and pulmonary ones that could
also be visualized with ultrasound and chest radiographs. The diagnosis is confirmed with
serology tests. E. histolytica trophozoites can be demonstrated in the aspirates of
abscesses (Becker 1980, Duma 1980). CT guided aspiration of the cerebral abscess is
diagnostic and therapeutic. Metronidazole 500mg thrice daily for 10 days eliminates the
cysts (Lenshoek et al 1958).
• Neurocysticercosis
Neurocysticercosis occurs when people ingest the eggs of Taenia solium, a pork tapeworm
whose eggs are found in human feces. Ingesting the eggs leads to tapeworm larvae
growing in many different human tissues, particularly brain and muscle. This leads to
seizures and more. The disease is most common where pigs are raised and sanitation is
poor, including much of South America and India. Treatment is with albendazole and
praziquantel.

5. • NEMATODES
Although many nematodes could infest the central nervous system, most are medical
problems and are unlikely to present to the neurosurgeon. Angiostrongylus cantonensis is
found in Australia, Papua New Guinea, South East Asia, Africa and other Tropical countries.
This can infect man accidentally through the ingestion of snails, crabs, prawns, and vegetables
if not properly cooked. It gives rise to meningitis-like illness, radiculitis or encephalitis.
Gnathostoma spinigerum is also found in South East Asia, Africa, the Middle East, Europe, and
the Americas. Eating uncooked or undercooked food especially meat, fish and chicken, as well
as drinking contaminated water may cause infection. The infection may involve the brain and
the spinal cord resulting in sensory and motor deficits. Massive cerebral hemorrhage has been
reported. Visceral Larva Migrans. is caused by several parasites. Toxocaria canis is the cause of
toxocariasis or visceral larva migrans. It is a canine parasite that causes accidental infection in
man. It is distributed worldwide. Involvement of the central nervous system may be in the
form of meningitis, encephalitis, or granuloma-like lesion. (Brown & Voge 1982, Hill et al
1985). Capillaria hepatica is a recognized cause of visceral larva migrans in Southeast Asia that
can cause cerebral granulomas (Cook 1989). Ascaris lumbricoides involvement of the brain has
been reported. (Brown & Voge 1982)
Trichinella spiralis is found in many parts of the world - Americas, Tropical countries of Africa,
and Thailand. Infection is from eating meat of infected animals such as pigs, polar bear, and
wild animals. Meningitis or cerebral hemorrhage may occur.
Loa loa is a microfilarial disease transmitted from man to man by flies of the genus Chrysops
and it is endemic in West and Central Africa. Although it characteristically causes subcutaneus
swellings known as "Calabar Swellings", it may produce meningoencephalitis probably due to
an allergic reaction to dead microfilaria causing occlusive thrombi. (Muller 1984, Negesse et al
1985) Dracunculus medinensis is a guinea worm infection that is endemic in West and Central
Africa, Western India, and Arabian Gulf. Infection is caused by drinking water contaminated by
infected Cyclops sp. The lesions are usually superficial in subcutaneus tissues. However, spinal
cord involvement may result from spinal extradural abscess also caused by the worm.

6. • Schistosomiasis
Schistosomiasis is caused by infection with small, flat worms called flukes. Usually,
these small, leaf-shaped worms cause intestinal, liver, kidney or bladder problems.
Globally, about one in thirty people carries these schistosomes. Like many parasites,
the life cycle of this organism is complex and involves many different stages. Humans
acquire the infection by contact with freshwater containing schistosomal larvae,
which penetrate the skin and migrate into the blood vessels, which they use to
travel through the body. The worms use suckers to adhere to the wall of the blood
vessel, where they can live for up to 30 years.
Most patients with this infection feel no symptoms at all. Sometimes, though, an
acute infection can be seen one day after exposure with an itchy rash. Two to eight
weeks later, a fever can develop. Later, as the schistosomes can spread to different
organs, various symptoms can occur. Sometimes, the worms spread to the spinal
cord, causing a myelopathy. This results in pain, bowel dysfunction, and weakness of
the regions below the level of infection. Permanent paralysis can result. In other
cases, the schistosomiasis can affect the brain, leading to epilepsy or elevated
intracranial pressure.
Because these worms can live in the body for years, with potential for serious
trouble at any time, infected persons should be treated regardless of whether they
have serious symptoms. Praziquantel is the treatment of choice. If the flukes have
invaded the nervous system, steroids should be given as well in order to reduce the
inflammatory response.

7. • Echinococcosis
Echinococcus is a tapeworm which, in the early stage of life, can cause cysts in living human tissue,
including the brain and spinal cord. Humans acquire the infection after eating contaminated food.
The disease is rare in the United States, but is more common in Africa, Central Asia, Southern South
America, the Mediterranean and the Middle East.
The initial stages of infection are always asymptomatic, and it may be years before the cysts cause
any problems. In the brain, the cysts can cause seizures or elevated intracranial pressure. In the
spinal cord, the cysts can cause cord compression and paralysis. Such central nervous system
infection is relatively rare, however—usually the cysts infect other organs, such as the lungs or liver.
Cysts can be found with a CT scan, but they're usually found when an imaging test is done for some
other reason. Cysts may need surgical maneuver, often with additional medical treatment with a
drug such as albendazole or praziquantel.
• Trichenella
This parasitic infection is caused by roundworms (nematodes), most commonly found in
undercooked pig meat, though it can be found in other types of meat as well. The infection is
relatively uncommon in the United States due to improvements in food preparation. Larvae invade
the wall of the small bowel and develop into adult worms. Worms then go on to release eggs that
grow into cysts in muscles. When the muscle is ingested by another animal, the cycle continues.
Severe trichenellosis can cause a meningoencephalitis. Headache is a common symptom. Swelling,
strokes, and seizures can also occur. The CT can show small cystic lesions throughout the brain.
Treatment is with albendazole or mebendazole, sometimes combined with prednisone in severe
cases.
As unappealing as parasitic infections are, it's worth noting that most of the time, these infections go
unnoticed. A high percentage of people throughout the world live with a worm or other parasite. As
close as we may be with these organisms, though, invasion of our central nervous systems is too
close for comfort, and must always be taken seriously.

8. • Cerebral Malaria
Without exaggeration, malaria is one of the most serious threats to human life throughout the entire
history of mankind. Over millenia, the disease has killed hundreds of millions of people. The workings
of this parasite are complex, but almost always involve being transmitted by an infected mosquito.
Here we will only briefly discuss one of malaria’s several tactics in human destruction: the direct
invasion of brain tissue.
Cerebral malaria can cause changes in consciousness or seizures. Without treatment, the disease
usually progresses to coma or death. With treatment, mortality is between 15 to 20 percent. Some
survivors, especially children, can have residual deficits like blindness, deafness, seizures, or cognitive
problems.
Cerebral malaria is most common where malaria is endemic, such as Africa. Visitors to such regions
can help prevent malarial infection with prophylactic medication and other preventative measures.
Those who suffer malarial infection require immediate treatment with either cinchona alkaloids such
as quinidine, or artemisinin derivatives such as artesunate. The latter is the drug of choice in severe
infection.
• Human African Trypanosomiasis
Trypanosomiasis, also called sleeping sickness, is caused by a protozoan parasite. Like malaria, the
parasite is spread by an insect host. American trypanosomiasis is transmitted by the assassin bug.
African trypanosomiasis is spread by the tsetse fly, which leaves a painful, 2 to 5 centimeter mark on
the skin. A rash may also follow. After a period of time, sometimes years, the parasite spreads from
the blood to the brain, leading to a meningoencephalitis and swelling. Headache, difficulty thinking,
personality changes, and movement disorders such as tremor or ataxia can result. The disease is fatal
without treatment. To diagnose the disease, the parasite must be seen under a microscope within a
sample such as cerebrospinal fluid. Treatment occurs with medications such as eflornithine or
melarsoprol—which can have serious side effects—but they're considerably better than allowing the
infection to go untreated.