Malaria cases fall with each year of HIV treatment in Ugandan patients

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Antiretroviral treatment was associated with a 75% decline in the incidence of malaria over four years in DART study participants, Ugandan and UK-based researchers reported last week at the Fifth International AIDS Society conference in Cape Town.

People with HIV are at especially high risk of malaria when they have very low CD4 counts, and malaria may cause a decline in the CD4 count. Much of sub-Saharan Africa is affected by malaria, including many areas with a high HIV prevalence.

The DART study was a five-year comparison of clinical versus laboratory and clinical monitoring for the management of antiretroviral treatment in Uganda and Zimbabwe.

Glossary

malaria

A serious disease caused by a parasite that commonly infects a certain type of mosquito which feeds on humans. People who get malaria are typically very sick with high fevers, shaking chills, and flu-like illness. 

person years

In a study “100 person years of follow-up” could mean that information was collected on 100 people for one year, or on 50 people for two years each, or on ten people over ten years. In practice, each person’s duration of follow-up is likely to be different.

retrospective study

A type of longitudinal study in which information is collected on what has previously happened to people - for example, by reviewing their medical notes or by interviewing them about past events. 

hazard ratio

Comparing one group with another, expresses differences in the risk of something happening. A hazard ratio above 1 means the risk is higher in the group of interest; a hazard ratio below 1 means the risk is lower. Similar to ‘relative risk’.

immune reconstitution

Improvement of the function of the immune system as a consequence of anti-HIV therapy.

Since participants were reviewed for clinical symptoms whenever they attended three-monthly study visits, or when acutely ill, researchers were able to conduct a retrospective review of 1020 trial participants receiving care at the Entebbe trial site in Uganda to determine risk factors for the development of malaria during antiretroviral treatment.

Febrile illness suggestive of malaria was investigated in 638 patients (2013 episodes). In 68% of cases plasmodium falciparum, the causative agent of malaria, was detected in a peripheral blood film, and a total of 51% of patients at the site were diagnosed with malaria.

In the first year of antiretroviral treatment the incidence of malaria was 591 cases per 1000 person years of follow-up; by year four the incidence had declined to 153 cases per 1000 person years, a decline of almost 75%. Duration of treatment is likely to be a surrogate for improvement in immune status, although this study could not directly evaluate the association between immune reconstitution and risk of malaria.

The factors associated with a reduced risk of malaria were cotrimoxazole use (adjusted hazard ratio 0.40, 95% confidence interval 0.33-0.48, p<0.001) and secondary or tertiary education (AHR 0.70 and 0.55 respectively).

The risk of malaria was greatest in individuals with baseline CD4 counts below 10 (AHR not stated), the investigators reported.

The investigators say that malaria prevention efforts should be particularly targeted towards those patients with advanced immune suppression and low educational levels, both prior to antiretroviral treatment and during treatment. They also note that antiretroviral treatment could have an indirect effect over time on the burden of malaria in settings where malaria is a serious problem.

Further information

A powerpoint presentation by Ronnie Kasirye and a webcast of this conference session are available on the IAS 2009 website.