Before the widespread use of potent combination ART, OIs were the principal cause of morbidity and mortality in this population. In the early 1990s, the use of chemoprophylaxis and better strategies for managing acute OIs contributed to improved quality of life and patient survival.6
However, the widespread use of ART starting in the mid-1990s has had the most profound influence on reducing OI-related mortality in HIV-infected persons in countries where therapies are accessible and affordable.6
Combination ART was offered to <10% of HIV-infected individuals in Oman in 2004.9
An estimated 500 Omani patients received ART in 2008.10
Despite the availability of ART in Oman, OIs continue to cause considerable morbidity and mortality for three primary reasons: 1) many patients are unaware of their HIV infection and seek medical care when an OI becomes the initial indicator of their disease; 2) certain patients are aware of their HIV infection, but do not take ART, and 3) some patients are prescribed ART, but fail to attain adequate virologic and immunologic response because of factors related to adherence, pharmacokinetics, or other unexplained biologic factors.11
Thus, although hospitalisation and death from OIs have decreased in those countries in which ART is accessible and affordable, OIs remain a leading cause of morbidity and mortality in HIV-infected persons.12
Clinicians should be aware of the epidemiology of such infections in Oman in order to provide comprehensive high-quality care for these patients. A wide variety of these infections are encountered in the HIV/AIDS population, including bacteria, fungi, viruses, and protozoa. Very often, these represent not new infections but the reactivation of an old infection.
In this study, 58% of people who were diagnosed with HIV presented with an AIDS-defining OI and more than half of them (53%) had two or more OIs. The proportion of persons with a CD4+ cell count of <200 cells/μL at the time of HIV infection diagnosis was 77%. This finding is consistent with data from India where 83.4% of patients were late presenters.13
However, data from Europe show that only one-third of patients were defined as late HIV presenters.14
Both the above findings were interesting. Whatever the underlying causes, reducing the number of late-stage diagnoses of HIV infection through earlier and more widespread testing, and promoting early introduction and adherence to ART will substantially reduce the burden of OIs. As mentioned earlier, 73% of the Omani patients who presented with one or more OIs were male; this warrants a second mention in order to reference the national percentage and its association with the epidemiology of HIV infections in Oman, where males accounted for 74% of all reported HIV/AIDS cases in 2008.10
PCP was the commonest AIDS-defining OI, accounting for 25% of all diagnosed OI events in our study. A total of 18 patients (23%) with HIV/AIDS had PCP as an AIDS-defining OI at their first presentation. The prevalence of PCP in our cohort was higher than that reported in Lebanon (10.9%), and is very much higher than in Europe where only 2–3% of PCP cases were reported among HIV/AIDS patients.15
Before the widespread use of primary PCP prophylaxis and ART, PCP occurred in 70–80% of patients with AIDS.17
All cases in this cohort occurred among patients with CD4+ counts of <200 cells/μL.17
A definitive diagnosis of PCP with a demonstration of organisms in induced sputum samples or BAL fluid was made in 11 patients. A presumptive diagnosis of PCP was made in the remaining 7 patients.
Oral candidiasis was the most common OI (59%) and our finding is similar to that reported in Nepal by Sharma et al
Some investigators from India, have reported oral candidiasis as the second most common infection in AIDS patients, while others have reported very low incidence of candidiasis (27.7%).19
TB was the commonest isolate reported in a few studies from Hong Kong21
Pulmonary TB was observed in 35% and extra-pulmonary TB in 21% of Omani cases. This is similar to data from Brazil where pulmonary TB was the commonest OI (52.9%).23
HIV infection is a strong risk factor for active TB in persons with latent M. tuberculosis
infection. Disseminated TB accounts for 15% of all OI events (14% of all HIV patients). Disseminated TB, on the other hand, was reported in 7.8% of the cohort from Lebanon.15
In 2008, there were an estimated 1.5 million new cases of tuberculosis among persons with HIV infection, and TB accounted for 26% of AIDS-related deaths.24
In the same year, 1.4 million patients with TB were tested globally for HIV, and 81 countries tested more than half of their patients with TB for HIV. Only 4% of all persons infected with HIV were screened for TB in the same year.25
TB is endemic in some countries like India, and is the commonest cause of death in AIDS patients.26
HIV patients are at increased risk of developing active TB because of the high rate of reactivation of latent infection and the high degree of susceptibility to new infection.27
infection was observed in only 3% of Omani cases. This is in contrast to data from Ethiopia where 21% of HIV patients had Cryptosporidium
is an enteric pathogen and a common cause of gastroenteritis in humans. In patients with HIV, cryptosporidiosis may cause potentially fatal complications, including bile duct damage.29
The rate of infection among individuals with HIV/AIDS in many countries has subsided considerably because of the use of ART.30
is the most important cause of invasive fungal disease in patients with HIV worldwide. Meningitis is the commonest clinical manifestation of invasive cryptococcosis in patients with HIV. In our study, Cryptococcus
meningitis accounted for 22% of OI events (21% of all HIV patients). Indian reports show the incidence of cryptococcal infection (including meningitis) to be only 6–8%, whereas it is about 5–11% in the USA, 33% in Africa, and 28.5% in Thailand.31
Interestingly, none of the patients in the Lebanese cohort developed cryptococcal meningitis.15
The exact explanation for such high incidence in Oman is unclear. As a result, primary prophylaxis for invasive cryptococcal disease is widely practised by many physicians caring for HIV-infected patients in Oman.
Toxoplasmosis, caused by the protozoon Toxoplasma gondii
, is one of the major OIs afflicting HIV patients. Serological tests play a crucial role in the diagnosis of toxoplasmosis in immune-competent persons.32
The prevalence rate of latent toxoplasmosis in HIV/AIDS vary from 3–97% based on ethnicity and other factors.33
Cerebral toxoplasmosis is the most common cause of focal neurological disorders in HIV patients. In our cohort, cerebral toxoplasmosis accounted for 12.5% of all AIDS-defining OIs (12% of all HIV patients). In a study from Lebanon, neurotoxoplasmosis was reported in 21.9% of the HIV-infected patients.15
This striking difference probably reflects differences in social behaviour between the two populations. In our cohort, all patients with cerebral toxoplasmosis had positive IgG for toxoplasmosis, CT/MRI evidence of compatible brain lesions, and clinical and radiological response to therapy for toxoplasmosis.
Both MAI and leishmaniasis were uncommon in our cohort, accounting for only 1.5% of all AIDS-associated OIs (1.3% of the cohort). Primary prophylaxis for MAI is not routinely practised in Oman.