A Serious Case of Parasitic Infection
Dung X. Dinh, M.D., Giang N. Trinh, D.Ph, Thomas D. Le, Ph.D.
Tóm Lược
Ký sinh trùng sống nhờ trên một ký chủ (hay sinh vật) sống khác
như súc vật và người. Ký sinh trùng sống với ký chủ, lấy thực phẩm từ ký chủ
nhưng không góp phần vào sinh hoạt của ký chủ. Một số ký sinh trùng gây kích
thích và trở ngại cho các chức năng cơ thể, một số tiêu hủy mô của ký chủ, và
phóng thích độc tố gây tổn hại và bệnh tật cho ký chủ.
Bài viết này đề cập đến trường hợp một du khách người Mỹ gốc Việt
trong một chuyến du lịch về Việt Nam, đã nhiễm phải bệnh giun đầu gai
(Gnathostomiasis) gây nên bởi một loại ký sinh trùng đặc biệt do bệnh nhân ăn
sống trái tim rắn hổ mang. Ký sinh trùng Gnathostoma spinigerum, một loại giun
tròn đ&Fiction and Moreu có móc đã xâm nhập qua đường tiêu hóa gây nhiều
biến chứng như đau vùng gan, nổi mày đay ở chân, sốt, ớn lạnh nhiều vào buổi
chiều tối. Số lượng bạch huyết cầu ăn phẩm eosin của người bệnh này lên cao đến
13,000 mili mét phân khối máu (13,000 mm3).
Sự chẩn định đúng bệnh và điều trị kịp thời với thuốc Albenza
(albendazole) do lời khuyên của một ký sinh trùng gia thuộc Trung Tâm Kiểm Soát
và Phòng Ngừa Bệnh Nhiễm Trùng đã chữa trị người du khách này hoàn toàn khỏi
bệnh.
Abstract
Parasites live off their
animal or human hosts, which provide them with food and shelter without
reciprocal benefits. They wreak havoc with their hosts' life processes by
destroying cells or releasing toxic substances, thereby posing a
life-threatening health hazard.
This article discusses a
serious case of parasitic attack suffered by a Vietnamese-American visitor to
Vietnam. By eating an uncooked cobra heart, he had allowed the Gnathostoma
spinigerum, a roundworm with a hooked head, to invade his stomach, and
cause swelling in the liver area, hives in the legs, fevers, and chills that
worsen in the evening. His eosinophil count reached an abnormally high level of
13,000 per cubic millimeter of blood.
A correct diagnosis and
timely treatment with the drug Albenza (albendazole), recommended by a
parasitologist at the Centers for Disease Control and Prevention, produced the
final relief.
Background
CN and his wife Q had
just returned from a visit to Viet Nam. They spent four days in Ho Chi Minh
City, where the various foods they ate were well cooked. When they visited Hue,
they enjoyed local specialties, which were also well cooked. Their travel took
them to Ha Noi, then to the seaside resort of Nha Trang. It was here that they
ate some raw shrimp dishes. CN also took a one-kilometer swim in the sea.
Back in HCM City, CN
joined a group of men friends in a drinking party during which delicacies such
as frog, field mice, lizard, and cobra were served. All of these were well
cooked with the exception of the snake bile, which was consumed raw with rice
wine. On the instigation of local friends, CN also ate a raw snake heart, on
the theory that it is a kidney tonic and an aphrodisiac.
Development of the Infection
Four days after
returning to the United States, CN took seriously ill, drained of his normally
bubbling energy, and was confined to bed. He suffered from mild fever and his
body temperature reached 103 degrees F. His condition was more tolerable in the
morning than in the evening, when the hives broke out in his legs. There were
nights when he felt pain in the upper right quadrant of the body, and chills
that required overheating in his room and several layers of blanket to
stabilize his condition. Antibiotics did not seem to work. His bodily
functions, such as urinating and bowel movements, were normal. His skin and
eyes did not show any yellowing effect. An examination of his ears, nose and
throat (ENT) was normal. There was no stiff neck. The white blood cell count
was only slightly elevated. A blood test to determine malaria infection turned
out negative, although there was an unusually high leucocyte count of 26,000,
more than half of which consisted of eosinophils.
Eosinophils (E) are
white blood cells distinguished by the presence in their cytoplasm of coarse
granules that stains orange red with Wright's or Giemsa stains. Although the
function of eosinophil is poorly understood, it is known for its ability to
ingest foreign particles ranging from pollen to impurities from pets. The
eosinophils release various substances from their eosinophilic granules. These
include major basic protein (MBP), cationic proteins, peroxidase,
arylsulphatase B, phospholipase D and histaminase. The granule contents are
capable of damaging a parasite's membrane.
If this reaction occurs
in the respiratory tract, the patient will experience profuse eye tearing, red
itchy eyes, a runny and irritated nose, and sometimes hard breathing
symptomatic of asthma. The eosinophil level is particularly high in cases of
infection by roundworms and tapeworms. In developed countries, where hygiene
standards are high, this level rarely exceeds 300/mm3 of blood.
Diagnosis and Treatment
Dr. Pamela Nagami, a
specialist in Infectious Diseases who treated CN, stated that his complete
blood count with 13,000 E per mm3 was among the highest she had ever seen.
Dr. Nagami conducted a
thorough review of CN's travel history, as described above, paying particular
attention to his diet, sleeping, and bathing habits, because Viet Nam is known
for tropical fever, typhoid fever and worm infection. Since CN turned up
negative in malaria testing, and had taken antibiotics, her focus was on worms.
Of the four known
filaria that infest the blood stream through mosquito bites, Viet Nam has two,
which are prevalent in the north. In filiariasis, the female mosquito releases,
depending on the timing of the bites (day or night) thousands of what are
considered to be pre-larval stages, which still retain the egg membrane,
referred to as microfilariae. In case of Wuchereria bancrofti, the
larvae introduced in the human body by bites from the female mosquito make
their way through the peripheral lymphatics to the larger vessels where they
reach maturity. The adult worms damage the lymphatic valve system causing the
lymph to drain to the extremities, and hence invading and swelling the
subcutaneous tissues. This condition is known as elephantiasis, which is
accompanied by high fever, chills, and a high E level. Since CN had no
reddening or swelling of lymph nodes, Dr. Nagami eliminated filiariasis as a
possible cause.
Next Dr. Nagami
considered trichinosis, an infestation caused by ingestion of undercooked food.
In this case the larvae could traverse the walls of the intestines and reach
other muscles, where they cause abnormally high CPK (creatine phosphokinase)
and E levels. Since CN's blood test did not show a high CPK level, trichinosis
was also eliminated.
The third condition,
schistosomiasis, a blood fluke which infests more than 200 million people
around the globe, is caused by quarter- or half-inch-long worms with a complex
life cycle, and carried primarily by fresh-water snails. Infestation does not
take place by direct contact with the snails. Instead the larvae travel through
fresh water and penetrate the skin of swimmers and farm workers. Although CN
took a swim off the Nha Trang beach, the condition was not entirely out of the
question since he also did eat raw shrimp. Nagami also considered Paragonimus
westermani, a kind of flat lung fluke that might have been ingested along
with raw fresh water crayfish or crab infected with metacercariae.
Millions of Far Eastern inhabitants suffer from this condition, which cause
chronic bloody coughs. CN did not have any coughs, and hence could not have
paragonimiasis.
An important fact to
note is that CN was the only person affected among others, including Q and his
cousins, during their Viet Nam trip. The only difference is CN had eaten raw
snake, which seems to indicate that parasites in snakes must be investigated.
There are cases of incidental infestation through parasites. Two came to mind:
Spirometra, a tape worm, and Gnasthostoma, a round worm, both carried by pets
such as cats, dogs, and other mammals.
The Spirometra
mansonoides causes a strange eye infection known as sparganosis. In
Viet Nam, particularly in the countryside of the north and central regions,
peasants of half a century ago would use poultice made from a frog's leg
muscles to treat open wounds and eye diseases for its refreshing effects. The
larvae would have a chance to infest the areas around the eyes. Eating a raw or
undercooked infected frog, snake, or small mammal would expose humans to the
same risk. The patient exhibits high E level and fever. When the infestation
reaches the intestines and other tissues, it accounts for painful swelling.
Under surgical procedure the gleaming white and slow-moving worms are found. CN
could be infested by the Spirometra.
The last diagnostic test
would involve the Gnathostoma spinigerum . The Gnathostoma
sp., which can mature only among dogs and cats and certain wild mammals
such as tigers, leopards, lions, minks, otters, opossums, and raccoons, is able
by transmission through various agents from feces to cyclops to fish, frog or
snake, to infest humans who ingest the latter raw or undercooked. The Gnathostoma
sp. clings to the stomach walls of their hosts by means of hooks in
their heads, and upon maturity lays eggs. Tiny-eyed cyclops in fresh water eat
these eggs, and are in turn eaten by fish, frogs, and snakes. The parasitic eggs
are thus transmitted from animal to animal.
When CN ate the snake's
heart, the larvae were released through digestion into his stomach. And because
CN is not a natural host, such as a dog or a cat, the larvae, which have an
expected life of up to ten years, had to pass through his stomach to migrate
into the abdominal cavity and aimlessly wander into his liver and other
subcutaneous organs. If they reached the brain there is no telling what the
consequences would be. CN exhibited all the signs of fever, pain in the liver
area, hives, and one of the highest E levels ever recorded.
Finally Nagami appealed
to the Centers for Disease Control and Prevention in Atlanta, where
parasitologist Sue Partridge concurred with Nagami's diagnosis and suggested
the anthelmintic albendazole (Albenza).
Although the CDC has no
blood tests for gnathostomiasis, a research center in the School of Tropical
Diseases in Bangkok, Thailand, has the facility for such tests under the
direction of Dr. Wanpen Chaicumpa.
Due to bureaucratic
procedures at the Bangkok Airport, two blood samples from CN had to be mailed
to Dr. Wanpen Chaicumpa before he received the sample. While waiting for the
test result, the drug albendazole was administered. After two days CN showed
signs of progress. Although the E level was at 25,000, other tests for dengue
fever, amebiasis ( Entamoeba histolytica ), and fecal
inspection all turn up negative. As CN continued steady progress toward
recovery, night fever began to abate.
About two weeks later,
CN's wife reported to Nagami the appearance of a red swelling the size of a
small egg on the left side of his stomach. A week later, the swelling was
removed surgically. Under the microscope the two-centimeter-long hard sample
showed live tissues filled with E. Deep under the skin is a tunnel running the
length of the sample littered with dead tissues. There were no worms, no hooked
heads, no cuticles, indeed, nothing at all. The quarter-inchlong worms had dug
a tunnel through his tissues, and had apparently vanished without a trace,
leaving behind a trail of E in hot pursuit.
Weeks later Dr. Wanpen
Chaicumpa's tests came through. They showed positive results for Gnathostoma
spinigerum under the Western blot analysis. As for the worms, Nagami
conjectured that they had disappeared, killed by the drug albendazole. In fact,
after several months CN's level of eosinophils has gradually become normal.
Conclusion
Thanks to the dedication
and professional competence of Dr. Nagami and associates, and the help from the
CDC, gnathostomiasis had been correctly diagnosed, the drug albendazole
(Albenza) appropriately administered, and CN's health completely restored.
Comment
It is important when
traveling to South America, Central Africa, the Middle East, India, and South
East Asia to take all the immunizations recommended by the CDC, and to exercise
caution about foods and drinks. Visitors to those areas should be vigilant
about infectious diseases, such as malaria, cholera, typhoid fever, etc., as
well as diseases caused by helminths, such as nematodes, flukes, and tapeworms,
which can infest humans through raw or undercooked food. And if they experience
discomfort upon their return home, they should immediately seek medical
treatment and inform their physician of the places they have visited.
References
1. Nagami, Pamela, M.D.,
Maneater, Renaissance Books, Los Angeles, 2001, pp. 15-32.
2. Jong, Elaine C., The
Travel and Tropical Medicine Manual, W.B. Saunders Co., Philadelphia, 1987.
3. Suntharasamai, P., M.
Riganti, S. Chittamas, and Desakorn, "Albendazole Stimulators Outward
Migration of Gnathostoma Spinigerum to the Dermis in Man", Southeast Asian
Journal of Tropical Public Health, 23, No. 4, December 1992, pp. 716-22.
4. Nopparatana.C., W.
Chaicumpa, P. Tapchaisri, P. Setasuban, and Y. Ruangkunaporn, "Towards a
Suitable Antigen for Diagnosis of Gnathostoma Spinigera Infection", Indian
Journal of Parasitology, 22, No. 8, December 1992, pp. 1151-56.
5. Kraivichian P,
Kulkumthorn M, Yingyourd P, et al, "Albendazole for the treatment of human
gnathostomiasis", Transactions of the Royal Society of Tropical Medicine
and Hygiene (London), 86, No. 4, July-August 1992, pp.
