Reactivation of Retinal Toxoplasmosis Despite Evidence of Immune Response to Highly Active Antiretroviral Therapy
Jason E. Stout
()
1
James C. Lai
0
Julia Giner
1
Carol Dukes Hamilton
1
0
Department of Ophthalmology, Duke University Medical Center
,
Durham, North Carolina
1
Division of Infectious Diseases and International Health, Department of Medicine
We report a case of retinal toxoplasmosis that occurred in a patient with acquired immunodeficiency syndrome who had a previous diagnosis of cerebral toxoplasmosis, despite the patient having had a robust immune response to highly active antiretroviral therapy. Clinical decisions about whether to discontinue secondary prophylaxis for opportunistic infections continue to be challenging.
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dition of clindamycin and topical corticosteroids, was
reinitiated. The patients CD4 count at the time that he
presented with blurred vision was 482 cells/mm3, and he had an
undetectable HIV load. After several weeks of therapy, the visual
disturbance resolved. Ophthalmologic examination was
repeated, revealing improvement in the patients condition.
Treatment with clindamycin and topical corticosteroids was
discontinued. The patient continued receiving secondary prophylaxis
(pyrimethamine, 50 mg/day, and sulfadiazine, 1 g b.i.d.), and
he was healthy at month 16 of follow-up. It was decided that
prophylaxis would be continued indefinitely.
Discussion. The case that we report illustrates that
although increases in T helper lymphocytes generally reflect
immune reconstitution, recovery of immunity to specific
pathogens is not measurable in an individual patient. Randomized,
controlled trials have demonstrated that it is relatively safe to
discontinue primary prophylaxis for PCP [4, 5], disseminated
Mycobacterium avium complex [8], and cerebral toxoplasmosis
[5, 6]. The data that support discontinuation of secondary
prophylaxis for toxoplasmosis or cytomegalovirus infection are
less conclusive [911]. The latest guidelines from the US Public
Health Service and the Infectious Diseases Society of America
state that it is reasonable to consider discontinuation of
secondary toxoplasmosis prophylaxis if the patient (1) has
completed receiving initial therapy for toxoplasmosis, (2) is
asymptomatic, and (3) has demonstrated a sustained increase in the
CD4 count (levels of 1200 cells/mm3 noted for 6 months)
while receiving HAART [12]. However, this recommendation
is primarily based on expert opinion, and the risk of recurrence
of toxoplasmosis in patients who meet the 3 aforementioned
criteria is unknown. Because fewer cases of cerebral
toxoplasmosis are occurring, probably secondary to the effect of
HAART, future clinical trials to define this risk appear unlikely.
Despite the uncertainty regarding discontinuation of
secondary prophylaxis for opportunistic infections, patients and
their clinicians are anxious to decrease the toxicity, pill burden,
and expense associated with complicated medication regimens,
if at all possible. The standard regimen for secondary
prophylaxis for toxoplasmosis requires that 9 additional pills be added
to the patients daily regimen. However, because a recurrence
of toxoplasmosis may have permanent effects on vision or
cerebral function, potential harm to an individual is significant
if secondary prophylaxis is stopped. Other possible approaches
may include reducing the frequency of dose administration for
secondary prophylaxis (e.g., reducing twice-daily
administration to thrice-weekly administration) [13] as well as using
alternative agents, such as trimethoprim-sulfamethoxazole and
atovaquone. In any case, clinicians must carefully discuss with
patients the uncertainties and risks involved, so that the most
informed decisions can be made.
In summary, the present report describes a case of ocular
toxoplasmosis in a patient who had a high CD4 count after
receiving HAART for 11 months. This report sounds a note of
caution in the swell of enthusiasm for stopping the use of
prophylactic medications for HIV-infected patients with
sustained CD4 count elevations. Until either reliable assays of
immune function recovery for specific pathogens or
more-extensive clinical data are available, we recommend that clinicians
take a cautious approach in the treatment of patients with
previously diagnosed toxoplasmosis and that they consider
indefinite use of secondary prophylaxis, regardless of the immune
response to antiretroviral therapy.
References
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