J Vector Borne Dis 44, December 2007, pp. 250–254
Prevalence of malaria as co-infection in HIV-infected individuals in a
malaria endemic area of southeastern Nigeria
C.C. Onyenekwea, N. Ukibea, S.C. Meludub, A. Ilikac, N. Abohb, N. Ofiaelid,
M. Ezaenie & A. Onochief
aDepartment of Chemical Pathology, bDepartment of Human Biochemistry, cDepartment of Community Medicine, eDepartment
of Immunology, College of Health Sciences, Nnamdi Azikiwe University, Nnewi Campus; dVoluntary Counselling and Testing
Unit, fHIV Laboratory Unit, Nnamdi Azikiwe University Teaching Hospital, Nnewi, Anambra State, Nigeria
Background & objective: The present study was conducted on the prevalence of malaria as co-infection
amongst ‘asymptomatic HIV’ and ‘symptomatic HIV’ subjects to see if such prevalence deviated
from that commonly reported in apparently health individuals in same locality.
Methods: A prospective study that involved 196 participants grouped according to their HIV status
as: ‘asymptomatic HIV seropositive group’ (n = 101); ‘symptomatic HIV seropositive group’ (n =
48) and ‘control HIV-seronegative group (n = 47). Blood samples collected from the participants
were used for double HIV screening by rapid immunoassay technique and immunochromatographic
technique, and for the diagnosis of Plasmodium falciparum malaria using rapid P. falciparum antigen
Results: The result showed that the prevalence of P. falciparum malaria as a co-infection amongst the
asymptomatic HIV seropositive group was 12 (11.8%) and amongst the symptomatic HIV seropositive
group was 16 (33.3%). However, the prevalence rate of P. falciparum malaria amongst the control
HIV seronegative group was 5 (10.6%) and the combined burden of P. falciparum malaria amongst
both groups of HIV seropositives was 28 (18.9%).
Interpretation & conclusion: The present study observed different prevalence rates of P. falciparum
malaria amongst the three groups. The prevalence was tripled in symptomatic HIV seropositive group.
This shows a clear departure from possible obtainable prevalence of malaria infection alone in this
malaria endemic area. Due to the mortality rates associated with malaria infection in an endemic
area, it may be necessary that routine malaria screening be adopted as part of the management policy
to check the co-infection.
Key words Asymptomatic – endemic – HIV – malaria – prevalence – symptomatic
HIV infection is on the increase in the sub-Saharan
Africa. This region is also known to be endemic for
malaria, particularly Plasmodium falciparum1.
Therefore, it may not be uncommon to observe co-
morbidity with both pathogens2–5. However, differ-
ent reports have it that incidence of malaria is not
common in HIV-infected individuals6–7, while others
have reported uncommon incidence of malaria in
HIV-infected individuals in malaria endemic areas2–5
although malaria transmission is unstable throughout
ONYENEKWE et al: HIV AND MALARIA CO-INFECTION IN NIGERIA
the year in these reports. Thus, it may be important to
investigate the prevalence of malaria in HIV-infected
subjects residing in a malaria endemic area with
stable transmission throughout the year. This will
help to know if pattern and burden of malaria
amongst HIV-infected subjects are similar in all en-
demic areas irrespective of stable or unstable trans-
mission throughout the year.
Material & Methods
This was a prospective study on 196 participants
(male = 77; female = 119; age range 2–70 yr) carried
out between the months of January and March 2007
at Nnamdi Azikiwe University Teaching Hospital
(NAUTH), Nnewi, Anambra state, Nigeria. The par-
ticipants were grouped as follows based on their HIV
Group 1: ‘Asymptomatic HIV group’ with 101 sub-
jects (male = 30; female = 71). Prior to this study,
these subjects did not know their HIV and P. falci-
parum malaria status. The HIV screening confirmed
these subjects as HIV seropositive. They were further
screened for P. falciparum malaria.
Group 2: ‘Control group’ consisted of 47 participants
(male = 24; female = 23). Prior to this study, these
subjects did not know their HIV and P. falciparum
malaria status. The HIV screening confirmed these
subjects as HIV seronegative. They were also scree-
ned for P. falciparum malaria.
Group 3: ‘Symptomatic HIV group’ consisted 48 par-
ticipants (male = 23; female = 25). Prior to this study,
these subjects knew their HIV status but did not know
their P. falciparum malaria status. They were those
living with HIV and have developed some signs and
symptoms. They were screened for P. falciparum
malaria. However, only 12 of them were placed on
From each participant in these three groups, 3 ml of
blood was collected for HIV screening and confirma-
tion and for P. falciparum malaria screening. The
participants in the present study gave informed con-
sent and the NAUTH Board of Ethical Committee
approved the study design.
Detection of antibodies to HIV-1 and HIV-2 in human
plasma: Two different methods were used namely
Abbott determineTM 1 & 2 which is an in vitro visu-
ally read immunoassay and immunochromatographic
test for the qualitative detection of antibodies to HIV-
1 & 2 in human plasma. For the Abbott determineTM
HIV-1 & 2 the procedure as described by the manu-
facturer was used for the analysis. Briefly, 50 μl of
participants’ plasma samples separated from corre-
sponding whole blood samples in EDTA were applied
to appropriately labelled sample pad. After 15 min of
sample application, the result was read. This method
has inherent quality control that validates the results.
Two visible red colours in the region labelled control
and patient represents HIV seropositive reaction
while a single red colour in the region labelled con-
trol represents HIV seronegative reaction. For the
immunochromatographic method for HIV-1 & 2 it
utilises immobilised antigen for the detection of an-
tibodies to HIV-1 & 2 in the plasma. It is used as a
point of care test and suitable for use in multi-test al-
gorithms. The procedure as described by the manu-
facturer was used for the analysis. In brief, 5 μl
plasma sample loop provided was used to collect the
participants’ plasma by touching it on the specimen
and allowing the opening of the loop to fill with the
liquid. The samples were dispensed into the sample
wells in appropriately labelled sample pad. Three
drops of the buffer supplied by the manufacturer was
added drop-wise into the appropriately labelled
sample wells. The results of the tests were read at zero
minute after the addition of the running buffer. This
method has inherent quality control that validates the
J VECTOR BORNE DIS 44, DECEMBER 2007
The presence of two pink/purple lines in the region of
test sample and control indicates HIV seropositive
reaction while a single pink/purple line at the control
region indicates HIV seronegative reaction. HIV se-
ropositive results’ using these two methods were used
to classify participants as presenting with HIV infec-
Diagnosis of P. falciparum: Whole blood was used
for the diagnosis of P. falciparum malaria using
Malaria Plasmodium falciparum Rapid Test Device
(Global device, USA). The principle is based on a
rapid chromatographic immunoassay for the qualita-
tive detection of circulating P. falciparum antigen in
the whole blood. This method utilises Gold conjugate
to selectively detect Plasmodium antigen. The proce-
dure was as described by the manufacturer. Briefly,
10 μl of the whole blood specimen from the partici-
pants were transferred into appropriately labelled
specimen cassettes containing sample well. Subse-
quently, three drops of buffer supplied by the manu-
facturer (approximately 120 μl) was added into the
sample wells. After 15 min the results were read. The
test device has inherent quality control that validates
the result. The presence of two pink lines at the region
of the control and test sample signifies presence of P.
falciparum malaria infection while the presence of
only one pink line in the control region signifies ab-
sence of P. falciparum.
Out of the 101 asymptomatic HIV-seropositive sub-
jects; 12 (11.8%) had P. falciparum malaria as co-
infection while the remaining 89 (88.2%) had no P.
falciparum malaria infection. Similarly, out of the 47
control HIV-seronegative subjects; 5 (10.6%) had P.
falciparum malaria while 42 (89.4%) had no P.
falciparum malaria infection. Furthermore, amongst
the 48 subjects of the symptomatic HIV-seropositive
group, 16 (33.3%) had P. falciparum malaria as co-
infection while 32 (66.7%) had no P. falciparum ma-
laria infection (Table 1). The total percent prevalence
Table 1. Prevalence of malaria infection amongst
asymptomatic HIV-seropositive, symptomatic HIV-
seropositive and control HIV-seronegative groups
GroupsMalaria –ve Malaria +veTotal
Asymptomatic HIV89 (88.2) 12 (11.8) 101 (100)
Control 42 (89.4) 5 (10.6)47 (100)
Symptomatic HIV32 (66.7) 16 (33.3)*48 (100)
*Three pregnant women inclusive; Figures in parentheses
Table 2. Prevalence of malaria and HIV co-morbidity
when asymptomatic and symptomatic HIV groups
were pooled together compared to malaria
prevalence in the control group
Malaria –ve121 (81.3)42 (89.4) 163 (83.2)
Malaria +ve28 (18.8)*5 (10.6)* 33 (16.8)
Total149 (100) 47 (100)196 (100)
#Both symptomatic and asymptomatic patients were included;
*Three pregnant women included; Figures in parentheses are
rate of P. falciparum amongst both the groups with
HIV seropositivity was 18.8% representing 28 P.
falciparum malaria positive participants out of the
149 (Table 2).
Sex distribution of P. falciparum malaria indicated
that 15 (45.4%) were males and 18 (54.6%) were
females with evidence of P. falciparum malaria.
However, three male and two female control HIV-se-
ronegative participants were included (Table 3).
The diagnosis of P. falciparum malaria parasite infec-
tion using P. falciparum antigen has been widely
accepted as a rapid antigen test for P. falciparum
malaria8,9. Its accuracy has also been put at 86–99%
ONYENEKWE et al: HIV AND MALARIA CO-INFECTION IN NIGERIA
compared with microscopic detection of malaria
parasites in smears10,11 as with very high specificity.
It has been recommended for use where microscopic
detection of malaria parasites in smears is not
possible. However, one of the limitations is that the
malaria antigen may still be detected after treatment
has been effected with successful clearance of para-
sites from blood10.
The prevalence of P. falciparum malaria amongst the
control subjects was 10.6%. Subjects in this category
were HIV seronegative. The prevalence of P. falci-
parum malaria in these subjects is a reflection of the
prevalence of this species of malaria in the popula-
tion. Similar prevalence has been reported from Ni-
geria amongst blood donors. In their report Erhabor
et al12 observed a prevalence rate of 10.2% amongst
the blood donors. Similar, prevalence has been repor-
ted in Cameroon showing changes in prevalence with
age13 and from rural area in southern Mozambique14.
This area is known as an endemic area with stable and
unstable transmission respectively .
However, amongst the asymptomatic HIV-infected
subjects, the prevalence rate of P. falciparum malaria
as a co-infection was 11.8%. This prevalent rate is
closely similar to that observed amongst the control
subjects. Since these subjects did not know their HIV
status prior to the screening, it may most likely be that
same factors limiting or predisposing to malaria may
closely exist in both the groups. It could also be that
the HIV infection is still quite recent in the asymp-
Contrastingly, the prevalence rate of P. falciparum
malaria as co-infection amongst the symptomatic
HIV subjects was 33.3%. This was almost tripled
compared with other groups. This possibly showed
that the factors conferring resistance to this species of
malaria might have been compromised in these sub-
jects. Thus this very high rate of malaria co-infection
in symptomatic HIV subjects calls for public health
concern. Bearing in mind that the study was carried
out in malaria endemic area with stable transmission
throughout the year. The implication is that they may
be exposed to such level of risk of susceptibility
throughout the year.
Studies reported elsewhere from malaria endemic
area with unstable transmission throughout the year,
through recruiting children and adults with malaria
infection observed respectively prevalence of HIV
in these subjects as 10.1%4 and 29.9%3. This report
though from a malaria endemic area with unstable
transmission also showed high incidences of malaria
and HIV co-infection. Therefore, irrespective of site
or location in a malaria endemic area, the problem of
HIV and malaria infections calls for concern as both
could lead to high mortality rate. Due to high mortal-
ity rates associated with malaria infection in an en-
demic area, it may be necessary that routine malaria
screening be adopted as part of the management
policy to check the co-infection.
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et al. Increased prevalence of severe malaria in HIV-
infected adults in South Africa. Clin Infect Dis 2005;
Table 3. Sex distribution of malaria infection
irrespective of HIV status of participants
SexMalaria +veMalaria –ve Total
Female 101 (61.6)$
Total163 (100) 33 (100) 196 (100)
+Twenty males were HIV seronegative; *Three males were
HIV seronegative; #Two females were HIV seronegative;
$Twenty-one females were HIV seronegative; Figures in
parentheses are percentages.
J VECTOR BORNE DIS 44, DECEMBER 2007 Download full-text
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Corresponding author: Dr. C.C. Onyenekwe, Department of Chemical Pathology, College of Health Sciences,
Nnamdi Azikiwe University, Nnewi Campus, Anambra State, Nigeria.
Received: 5 May 2007Accepted in revised form: 9 June 2007
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