1. 335 Plasmodium Species Infecting Children Presenting with
Malaria in Uganda
Victor Asua,1 Stephen Tukwasibwe,1 Melissa Conrad,2 Andrew Walakira,1 Joaniter I. Nankabirwa,1 Levicatus Mugenyi,1
Moses R. Kamya,1,3 Samuel L. Nsobya,1,4 and Philip J. Rosenthal2
1Infectious Diseases Research Collaboration, Kampala, Uganda; 2Department of Medicine, University of California, SanFrancisco, California, USA; 3Department of Medicine, Makerere University, Kampala, Uganda; 4Deparment of Pathology, Makerere University, Kampala, Uganda
Methods
Results
Background
A large proportion of malaria in sub-Saharan Africa is caused by P. falciparum. P. malariae and P. ovale have been considered uncommon. P. vivax was considered very uncommon due to the high prevalence of Duffy antigen negativity in Africans. However, recent molecular studies have shown varied prevalence of all species, including evidence for P. vivax infections in Duffy-negative individuals. Different plasmodial species require different therapeutic and control measures. Thus, understanding the distribution of plasmodial species is important to guide optimal implementation of malaria control measures.
Ten sites representing different regions of Uganda were selected (Figure 1). Five sites underwent regular indoor residual spraying of insecticides (IRS) either from (3 sites) or (2 sites).
Nearly 10% of the children had either mixed or pure non-falciparum infections
Table 1. Distribution of plasmodial species identified by PCR.
Fifty dried blood spots were collected from children 6 months to 10 years of age with malaria diagnosed by either HRP-2 based RDT or Giemsa stained blood smear.
Plasmodium species were detected by nested PCR for the 18S rRNA gene followed by electrophoresis of reaction products. Differences in prevalence of plasmodial species were compared using Fisher’s exact test, and P values <0.05 were considered statistically significant.
Species
Number (% of total)
P. falciparum
435 (91.8)
P. falciparum and P. malariae
19 (4.0)
P. falciparum and P. ovale
14 (3.0)
P. falciparum and P. vivax
3 (0.6)
P. falciparum, P. malariae, and P. ovale
1 (0.2)
P. malariae
P. malariae and P. vivax
Objective
Most infections were P. falciparum, as expected, but 8.2% of the samples with plasmodial infections had either mixed or pure non P. falciparum infection
To evaluate the distribution of plasmodial species in different regions of Uganda with varied malaria transmission intensity
Figure 1. Study districts and health centers (HC).
There were considerable differences in the prevalence of plasmodial species in the 10 study districts
High prevalence of non-P. falciparum infections at sites with prior indoor residual spraying
Table 2. Plasmodium species identified at 10 sites in Uganda.
Table 3. Prevalence of non-falciparum infections in sites with history of recent IRS.
Site
IRS duration N
Method of diagnosis
Plasmodium species identified (% of total)
District
Microscopy
RDT
Any
P. falciparum
P. malariae
P. ovale
P. vivax
Agago 50 1 49
49 (100)
2 (4.1)
Amolatar
2014- 2 48
50 (100)
13 (26)
2 (4.0)
Arua
None 42
42 (100)
Jinja 35 15
47 (95.9)
5 (10.2)
1 (2.0)
Kabale
Kanungu
48 (100)
1 (2.1)
Kole 46
46 (100)
9 (19.6)
Lamwo 44
44 (100)
1 (2.3)
Mubende
3 (6.3)
Tororo 23 27
Total
499
176
323
474
472 (99.6)
22 (4.6)
15 (3.2)
4 (0.8) n %
p value
IRS sites
27/189
14.6
0.0013
Non IRS sites
13/285
4.6
Prior use of IRS was associated with a higher prevalence of non-falciparum infections.
Summary and Conclusions
Although P. falciparum is clearly the dominant malaria species in Uganda, other species were quite common.
The prevalence of non-falciparum infections was greater at sites with a recent history of IRS.
Detection of other species has important implications on malaria control.
This result suggest that, decrease in malaria transmission may be accompanied by increase in prevalence of non-falciparum infections.
Attention to non-falciparum infections is important, as treatment and control recommendations vary according to species.
Our results suggest the need to follow the prevalence of different malaria species in Africa.
P. falciparum was predominant, but non-falciparum infections were seen at many sites.
Acknowledgement
We thank the staffs of the 10 health centers. Funding source: NIH (Fogarty International Center and NIAID)