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Case
1
A
44-year-old male is seen at a physician's office in the United States,
during a week-end, for suspected malaria.
The
patient was born in Pakistan but has lived in the US for the past 12
years. He travels frequently back to Pakistan to visit friends and relatives.
His last visit there was for two months, returning 11 months before
the current episode. He did not take malaria prophylaxis then.
Five
weeks ago, he was diagnosed with malaria and treated at a local hospital.
The blood smear at that time was reported by the hospital as positive
for Plasmodium malariae (schizonts, trophozoites). He was then
treated with 2 days of IV fluids (nature unknown) and tablets (nature
unknown), and recovered.
The
patient now presents with a history of low grade fever for the past
few days, with no other symptoms . A blood smear is taken and examined
at a hospital laboratory by the technician (no pathologist is available
on this week-end). Through a telephone discussion, the technician states
that she sees 4 parasites per 1000 red blood cells, with rings, "other
forms with up to four nuclei", and that some of the infected red
blood cells are enlarged and deformed.
Question
1. What is your most probable diagnosis?
Question
2. What treatment approach would you recommend, based on this clinical
history and on the fact that the microscopy findings will not be confirmed
by a pathologist for at least 24 hours?
The diagnosis of P. vivax malaria is later confirmed by
review of a blood smear available from the first episode
(Figure), and by a PCR positive for P. vivax on blood collected
during the current episode.
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P.
vivax
schizont
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P.
vivax
gametocyte
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The
microscopic
diagnosis of P. vivax is based on the following: a) the infected
red cells are enlarged and deformed; b) the schizont shown contains 20
merozoites (schizonts of P. malariae and P. ovale have fewer
merozoites; and in P. falciparum schizonts are not usually seen
in the peripheral blood); c) the round gametocyte shown, contained in
an enlarged red cell. (In this case, the typical Schüffner's dots
were not visible, probably due to staining problems.)
Question
3. To prevent further relapses from dormant liver stages, what would you
recommend?
Question
4. Should this patient have taken preventive measures against malaria
for his visit to Pakistan, considering that he was born there, and probably
would have visited only cities?
Main Points
- Travelers to Pakistan (including those visiting friends and relatives)
need to take prophylaxis (atovaquone-proguanil
(Malarone®), doxycycline or mefloquine).
- Clinical history and travel history, and careful microscopic examination,
probably would have directed the diagnosis toward P. vivax during
the earlier episode.
- P. vivax malaria should be treated with chloroquine,
except when acquired in Papua New Guinea and Indonesia, areas with
high prevalence of chloroquine-resistant P. vivax. After a
normal G6PD test, patients should get a radical cure with primaquine
(30 mg per day for 14 days).
Page last modified : April 23, 2004
Content source: Division of Parasitic Diseases
National Center for Zoonotic, Vector-Borne, and Enteric Diseases (ZVED)
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