Introduction

Malaria is described as a disease of poverty and underdevelopment and undoubtedly the most complex and severe public health challenge in the vast majority of tropical and sub-tropical regions of the world, with 300 to 500 million cases and 2 to 3 million deaths per year [₁]. The sub-Saharan Africa still remains the worst affected region and records about 90% of all malaria deaths in the world today [₂]. This is because majority of infections are caused by Plasmodium falciparum, the most dangerous of the four human malaria parasites (P. falciparum, P. ovale, P. vivax, P.malariae), accounting for an estimated 1.4 to 2.6 million deaths per year in this region [₂,₃]. In malaria endemic regions of the sub-Saharan Africa, pregnant women are highly susceptible to malaria with an estimated 24 million pregnant women affected [₄]. This has a great implication for maternal, fetal and infant health. For instance, each year between 75,000 and 200,000 infant deaths are attributed to malaria infection in pregnancy globally [₄,₅]. This is in addition to the contribution of malaria to adverse pregnancy outcomes including low birthweight (LBW)(through prematurity or interuterine growth retardation IUGR) which is known to be the single greatest and most important risk factor for neonatal and infant mortality [₆,₇]. Furthermore, in several areas where malaria in pregnancy is common a severe degree of fetal anemia is reported [₈]. Fetal anemia has been described as an important public health issue because it is one of the major risk factors for infant anemia which is a life threatening condition and an important cause of hospital admission in many developing countries [₉,₁₀].

The adverse perinatal outcomes associated with malaria in pregnancy, makes early and accurate diagnosis of malaria absolutely imperative. Early and accurate diagnosis as well as appropriate case management are essential to addressing the malaria burden in pregnancy and its outcome, and have been advocated consistently by the World Health Organization (WHO) [₁,₂]. Late and inaccurate diagnoses are major contributors to malaria mortality and to mortality from non-malaria illnesses, especially bacterial diseases, that malaria symptoms can resemble [₁₁,₁₂]. Thus the diagnosis of malaria in endemic areas of the tropics is considered an enormous challenge particularly in the sub-Saharan Africa [₁,₁₃]. Two major factors responsible for this are; first, most diagnosis of malaria, and decisions on the subsequent management of the disease, continue to be based on symptoms and signs that are poorly specific across a range of epidemiological settings [₁₁,₁₄]. Secondly, microscopic examination of blood smears still remains the only laboratory technique used for malaria diagnosis in most settings and this is labor intensive, requires significant skills and time, which can cause therapeutic delays [₁₅,₁₆]. In most African health centers for instance, microscopy standards are sub-optimal and sensitivity is notoriously low due to the lack of high quality equipment, the use of low quality stains and other reagents, and lack of supervision and trained staff [₁₇].

The importance of early, less cumbersome and yet accurate diagnosis of malaria particularly in high risk groups as pregnant women necessitated the introduction of rapid malaria diagnostic tests (RDTs) [₁₆,₁₇]. The WHO has recognized the RDTs as potential solution to improve malaria diagnosis because they can be used at the periphery of health services where laboratory equipment, electricity, and personnel with minimal training may be absent and they have lower capital and maintenance costs, and require less training than microscopy [₁₈]. Most of the RDTs are immuno-chromatographic dipstick assays that detect either histidine-rich proteins-2 (HRP2) produced by infected red blood cells or parasite lactate dehydrogenase, an enzyme present in the glycolytic pathway of the parasite and the RDTs produced by a variety of manufacturers have been evaluated as diagnostic tests for malaria [₁₃]. In this study the RDT that detects P. falciparum HRP2 was used to evaluate maternal malaria at childbirth and its relationship with birth weight and fetal hemoglobin levels.

Materials and Methods

Study Area

Ethical Considerations

Study Population/Sampling Technique

Laboratory Analysis

Statistical Analysis

Results

A total of 300 women were enrolled in this study and of these 59(19.7%, 95%CI., 15.2-24.2%) were positive for malaria infection as indicated by the RDT. The birth weight values of 211 and fetal hemoglobin levels of 192 newborns were determined, the rest could not be assessed due to logistic problems at the labor ward of the hospital. The prevalence of LBW (<2.5kg) was 24.6% and the prevalence was significantly higher among babies born by mothers with malaria infection (30.4%) than those uninfected (23.0%) (F-ratio=14.8, df₁/df₂=2/3, P<0.05). The mean birth weight was lower among babies from malaria infected mothers than those from uninfected mothers (2.45kg vs. 2.80kg) (Table 1).

Figure 1

Table 1: Association of maternal malaria infection at childbirth with birthweight in Abakaliki, Nigeria.

The prevalence of fetal anemia (Hb<12.5g/dl) was 65.1% and was slightly higher among newborns from malaria infected mothers (65.8%) than those from uninfected mothers (64.9%). Statistically no significant difference was found in the trend (?2 =0.01, df=1, P>0.05). The mean fetal hemoglobin concentration of newborns from malaria infected mothers was 11.05g/dl, while that of newborns from uninfected mothers was 11.87g/dl (Table 2).

Figure 2

Table 2: Association of maternal malaria at childbirth with fetal haemoglobin (Hb) concentration in Abakaliki, Nigeria

Discussion

Improved diagnosis of malaria in pregnancy in endemic regions of low income setting would continue to be an indispensable requirement to the roll back malaria initiative of the WHO. In this study we recognize the importance of the RDT and attest to its usefulness in rapid and less cumbersome maternal malaria diagnosis. A maternal malaria prevalence of 19.7% was obtained in this study using the Smart Check P.f RDT. This is comparable to the prevalence rates ranging from 2.6% to 81.1% obtained from various malaria endemic regions using various kinds of RDTs [₂₂,₂₃,₂₄,₂₅,₂₆].

It is suggested that RDTs in the nearest future would become major epidemiologic tools in the assessment of the impact of malaria during pregnancy.

In this study LBW was significantly associated with maternal malaria infection at childbirth (P<0.05). Although there is paucity of information on the use of RDT as an epidemiologic tool to evaluate maternal malaria and its relationship to birthweight, information however abounds on the use of malaria microscopy technique in various maternal malaria-birthweight related studies. And findings from these studies have consistently indicated that malaria infected mothers had higher prevalence rates of low birth weight newborns compared to those of the uninfected mothers [₇,₂₃,₂₇]. In fact falciparum malaria during pregnancy has long been recognized as an important determinant of low birth weight [₆,₇]. A number of randomized controlled trials of preventive antimalarial measures during pregnancy have confirmed this causal effect by showing that preventing malaria increases birth weight [₂₈,₂₉].

Findings from this present study indicated that the prevalence of fetal anemia was slightly higher among babies born by malaria infected mothers compared to those of the uninfected mothers, and of course the difference was not statistically significant (P>0.05). As with maternal malaria-birthweight studies, there is also paucity of information on the use of RDTs in maternal malaria-fetal anemia related studies. However available studies in which the microscopy technique was used to assess maternal malaria in relation to fetal anemia showed conflicting outcomes. In Kisumu, Kenya, and southern Malawi, babies born to mothers with detectable P. falciparum parasitemia on a peripheral blood film at delivery had a lower mean Hb level at birth compared with babies children born to mothers free of parasitemia at delivery [₉,₃₀]. On the contrary, in a similar study conducted in Blantyre, Malawi, even though malaria was associated with a reduction in maternal hemoglobin, no reduction in cord hemoglobin and no significant relationship between maternal and cord hemoglobin levels were found, furthermore authors noted that cord blood markers of hematological and hypoxic statuses did not differ between malaria-infected and uninfected women [₃₁]. Since the etiology of fetal anemia is complex and multifactorial further studies that will incorporate the assessment of other possible causes of fetal anemia are advocated.

In conclusion it is pertinent to state that a major drawback of this study was the lack of quantification of parasitemia which is a limiting factor associated with all RDTs [₁₃]. Also the possibility of false positive and false negative results cannot be completely overruled as a result of cross-reactivity. Nevertheless, the urgency and importance of obtaining results quickly from the examination of blood samples from pregnant women with suspected acute malaria makes RDTs absolutely imperative. This is because early diagnosis is an indispensable requirement to appropriate case management of malaria in pregnancy in order to avert its associated adverse perinatal outcomes.

Acknowledgement

Correspondence to

C.J. Uneke Department of Medical Microbiology/Parasitology, Faculty of Clinical Medicine, Ebonyi State University, P.M.B. 053 Abakaliki- Nigeria Tel: 234-08038928597; Fax: 234-043221093; E-mail: unekecj@ yahoo.com