Does malaria enhance HIV
transmission?
Both malaria and human immunodeficiency virus (HIV) infection are endemic in many parts of
the world. People with HIV infection are more susceptible to malaria due to their
depressed body immunity. But does malaria enhance HIV transmission and accelerate the
disease progression? James G Kublin from Fred Hutchinson Cancer Research Center from
Seattle, USA, and his team conducted a prospective cohort study in Malawi (Africa) to find
out the changes in concentration of virus (virus load) in HIV-infected adults who
didn’t have malarial infections at the time of enrolment. The underlying idea was
that the malarial parasite causes an increase in enzymatic activities that might promote
HIV virus replication and, thereby, increase the HIV virus load. Individuals with
increased HIV virus concentration in blood transmit the infection more effectively and
have accelerated progression of the clinical disease. The researchers were of the opinion
that a better understanding of this concept is necessary because co-infection is a very
common phenomenon, consequences of which might be of importance to clinical and public
health. Scientists used a prospective cohort
design to assess the effect of malaria on concentration of HIV virus in blood over three
time points — during the enrolment visit when persons did not have malarial parasite
in their blood; during an episode of malaria; and during a visit about eight weeks after
the episode when the person had neither malarial parasite nor any further episode of
malaria. All study subjects were adults aged at least 18 years and HIV positive.
Viral
load |
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The findings showed that the concentration of HIV virus
in the blood increased significantly with malaria, especially when the individuals had
fever and parasite density more than 2,000 cells per microlitre and baseline CD4
(lymphocyte) counts more than 300 cells per microlitre. Data analysis also showed that
increase in malaria coincides with a significant increase in HIV viral load (see Graph:
Viral load).
The study also revealed that the increased HIV virus
concentration was reversible within eight to nine weeks in individuals who had been
treated for malaria and the viral load reached almost the baseline level. The findings
imply the importance of concerted efforts to prevent HIV and malaria in areas where both
diseases are endemic. James Whitworth of infectious disease epidemiology of London School
of Hygiene and Tropical Medicine supporting the views of Kublin (in the same issue of The
Lancet) concurred there is a possibility of 50 per cent increase in HIV transmission
during the short period of higher viral load in blood during malaria. In India, this study
is of special importance, as the country is known to be malaria endemic and also ranks
second, after South Africa, in the world in terms of total HIV infection cases.
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