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Background:
As HIV spreads, it interacts with other infectious diseases,
facilitated by the increase in numbers of immunosuppressed
individuals and because its own clinical course can be altered by
other infections. Infectious diseases often ‘synergize’, or
negatively affect each other, and this is most noticeable with HIV
and tuberculosis (TB). In areas of high HIV prevalence, the incidence
of TB infection is increased, with a resultant increase in mortality.
In addition, susceptibility to HIV can be increased by other
infections, notably sexually transmitted infections (STIs), leading
to high rates of HIV transmission in communities with high prevalence
of STIs.
In Africa, the HIV pandemic has been superimposed on the longstanding
malaria pandemic, where malaria caused by P. falciparum is consistently one of
the major causes of mortality in infants and children. The high prevalence
of both HIV and malaria infection in Africa means that even small
interactions between the two could have substantial effects on
populations.
With the inception of the Roll Back Malaria partnership in 1998,
there was recognition that previous gradual declines in malaria
mortality had been reversed during the 1990’s, and that interactions
between malaria and HIV could be one contributor.
Early research did not indicate any direct, biological association
between HIV and malaria, although it was noted that
malaria-associated anaemia treated with unscreened blood transfusions
contributed to HIV transmission. In more recent years, three key
issues have focused much of the research effort:
- Does HIV/AIDS increase
susceptibility to malaria infection or increase severity of acute
malarial episodes?
- Does malaria infection accelerate
progression of HIV/AIDS?
- What is the impact of malaria and
HIV co-infection during pregnancy?
Current Status
Effect of
HIV on malaria
HIV infection increases the incidence and severity of clinical
malaria. In non-pregnant adults, HIV infection has been found to
roughly double the risk of malaria parasitemia and clinical malaria.
In east and southern Africa, where HIV prevalence is near 30%, it is
estimated that about one-quarter to one-third of clinical malaria in
adults (including during pregnancy) can be accounted for by HIV.
Little research has been carried out in children, although anaemia
from multiple causes is common and associated with increased
mortality in HIV-infected children.
Effect of malaria on HIV
Recent research is adding to the growing body of
evidence documenting the effect of malaria on HIV. Acute malaria infection increases viral load, and one study
found that this increased viral load was reversed by effective
malaria treatment. This malaria-associated increase in viral load
could lead to increased transmission of HIV and more rapid disease
progression, with substantial public health implications.
In Uganda, a study found that daily cotrimoxazole prophylaxis among
HIV-infected adults reduced malaria incidence by 80%. Although this effect would be expected to vary
depending on epidemiological setting and patterns of drug resistance,
it may be relevant for both pregnant women and adults.
Co-infection
of HIV and malaria during pregnancy
Malaria infection is more frequent and more severe in HIV-positive
pregnant women in malaria-endemic settings. Multigravidae (having had
one or more previous pregnancies) with HIV
infection are similar to primigravidae (first pregnancy) without HIV infection in terms
of susceptibility to, and negative consequences of, malaria
infection. Therefore, in the presence of HIV infection, the risk
associated with placental malaria appears to be independent of the
number of pregnancies.
Pregnant women infected with both malaria and HIV are at higher risk
of developing anaemia, delivering a low birth weight infant, and
delivering prematurely. Higher viral load increases the likelihood of
maternal-to-child transmission (MTCT) of HIV. Malaria infection
during pregnancy increases risks of MTCT in the intrauterine and
intrapartum period as well as during the breastfeeding period,
presumably by increasing HIV viral load.
WHO PowerPoint presentation:
Malaria, Pregnancy, and HIV Infection
Technical Issues
- If the transient elevation in
viral load associated with malaria infection can be reversed with
effective malaria treatment (as shown by prospective studies),
malaria prevention and control may prove to be beneficial in
reducing HIV transmission and slowing progression to AIDS.
- Large-scale use of
trimethoprim-sulfamethoxazole (cotrimoxazole) for prophylaxis of
opportunistic infections in HIV-positive patients, although of
possible benefit in reducing the incidence of malaria, may also
increase drug pressure for other antifolate combinations. This may
potentially accelerate resistance to sulfadoxine-pyrimethamine
(SP), which is being increasingly used for the treatment of acute
uncomplicated malaria in Africa and antenatal IPT programmes.
Conversely, expanding use of SP in Africa might further the
development of resistance to cotrimoxazole by other pathogens, such
as Streptococcus pneumoniae. The effectiveness of both of these
drugs needs to be carefully monitored in country programmes.
- It is estimated that 5% to 10% of
new HIV infections are caused by unsafe blood products. This has
enormous implications for the management of severe anaemia,
including that which occurs during childhood as a result of severe
malaria infection (see below).
UNICEF’s
Role:
Fighting HIV/AIDS is one of the five organizational priorities under
the MTSP, and UNICEF ESARO has identified HIV/AIDS as the “priority
of priorities” for the region. As a result, countries are to
re-orient their programmes to reflect this priority, creating
opportunities for linkage and collaboration across various programme
areas.
The association between HIV and malaria highlights the need for
prevention and control of both of these global pandemics to be
synergistic. In other words, prevention of HIV/AIDS should be viewed
as an important component of malaria control in countries with high
rates of HIV seroprevalence, and malaria prevention and control
should be viewed as an important element in the prevention and
control of HIV/AIDS in malaria-endemic countries. This requires the
formation of effective partnerships and improved collaboration
between the two programme entities. For the co-infected pregnant
woman, effective delivery of interventions for the prevention and
control of both malaria and HIV, including PMTCT as appropriate, is
vital.
The implications for UNICEF country programmes revolve around two key
areas:
- Management and Control of Anaemia:
This is particularly important for two high risk groups, infants
and pregnant women. Anaemia related deaths can be reduced by an
integrated programme which includes malaria prevention and control,
particularly ITNs and intermittent preventive treatment (IPT) for
both pregnant women and infants. Reducing the incidence of severe anaemia through malaria
control activities, and other public health interventions, would
lessen the need for the use of possibly unsafe blood products for
transfusion.
- Improved Antenatal Care: High
rates of antenatal attendance by pregnant women in Africa suggest
that the effects of HIV and malaria during pregnancy could be
approached through a “programme partnership” for improved antenatal
care. Joint
programming to strengthen antenatal care, including access to HIV
diagnosis and antiretroviral drugs for PMTCT, in addition to IPT,
distribution of ITNs, and improved malaria case management, could
have significant impact and long-term benefits for women and
children.
Linking two high priority UNICEF
programmes (PMTCT and RBM), around efforts to strengthen antenatal
care, has the potential to reduce maternal-to-child transmission of
HIV and improve outcomes for women and children. In both cases, it is
important to monitor coverage of interventions to control anaemia and
improve antenatal care, so that the impact of UNICEF country
programmes can be assessed.
Additional Readings
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