The data show that the incidence of TE before 1998 in this Puerto Rican AIDS cohort was higher than one reported by previous studies in the United States for the same time period.6
For example, Jones and others in their study of 12,982 AIDS persons in eight US states and Puerto Rico, reported a TE incidence three times lower than the one found in our AIDS group. After the implementation of HAART in the Island the incidence of TE decreased significantly; nevertheless, it remains higher than the one reported in the continental United States after the introduction of HAART. Unfortunately, no data has been reported in the US AIDS population on the TE incidence after 1997 so that a direct comparison is not possible. The study also indicates several changes in the clinical and socio/demographic characteristics of HIV-infected persons with TE, since the introduction of HAART, that is consistent with previously published studies.1,5,9,10
In Puerto Rico the full implementation of HAART was present in 1998, and our study detected a significant decline of TE incidence and mortality afterward. Furthermore, we showed a substantial reduction in the 1-year mortality among those TE patients who received HAART (HR 0.48) and a beneficial trend in those with a higher CD4 + T-cell count (HR = 0.62) at the time of TE diagnosis. It is well accepted that HIV infection leads to a severe CD4 + T-cell count depletion with severe immunological damage that promotes the reactivation of T. gondii
, which generates the target organ damage.11
Therefore, the more competent the T-cells mediated cellular immunity, the better the immunological host capacity to maintain quiescence of the T. gondii
The use of ART and in particular HAART produce an effective HIV viral load reduction, with a resultant improvement in the quantity and quality of the CD4 + T-cells, leading to an improved immune coordination and synergy that should decrease the magnitude and extent of target organ damage caused by T. gondii
This study found a significant increment in the TE prophylaxis beginning in 1995 that concord with the time when this recommendation was implemented. However, this prophylaxis did not produce a significant protective effect in the mortality risk of the studied TE cases. Inadequate compliance with the TE prophylaxis therapies might explain this finding. Unfortunately, this dataset does not include information on this prophylaxis adherence.
Despite the important reduction in the incidence and improvement in the prognostic outlook of TE in these Puerto Rican AIDS persons with the use of ART and HAART, an important number of patients continue to suffer from this devastating infection. Strategies for the prevention of TE, prompt recognition, adequate prophylaxis and management of the infection, and the institution of adequate and prompt ART, continue to be of vitally important for controlling this infection. Consequently, primary prevention measures that minimize the risk for acquiring T. gondii
should be advised and reinforced in Hispanic HIV-infected persons, such as this group; not eating raw or undercooked meat, including pork or venison, and washing hands after contact with raw meat, after gardening, or after having contact with soil need to be emphasized. In addition, fruits and vegetables should be washed before eating them raw. If patients own cats, their litter box should be changed daily preferable by other persons. These animals should not be given raw or undercooked foods. Furthermore, HIV-infected patients should be assessed for T. gondii
antibodies at the time of HIV diagnosis and high risk populations for developing TE, including T. gondii
seropositive persons with CD4 + T-cell count < 100 cell/µL should receive TE prophylaxis promptly and adequately.13
Limitations of our study include that the AIDS persons were selected from a passive surveillance cohort, in which patients had come to the hospital or outpatient facilities to have the data collected, otherwise the data would be lost. Thus, increasing the probability of lost to follow/up can lead to missing data that could affect the study findings. The study is not a population-based survey that could be generalized to all the AIDS patients on the Island.
In conclusion, the study showed a marked reduction of the TE incidence and mortality in this cohort of AIDS persons after the implementation of HAART in the Island. However, it continued to be higher than the one reported in the AIDS mainland population before HAART. An early diagnosis and referral for HIV treatment is highly recommended for this high-risk population. The immunological improvement produced by these opportune and adequate HIV therapies will reduce significantly the T. gondii reactivation. In addition, TE preventive and prophylaxis efforts directed to reduce the T. gondii infection and reactivation need to be emphasized and evaluated in further studies.