Reliability of rapid diagnostic tests in diagnosing pregnancy-associated malaria in north-eastern Tanzania

Abstract

BackgroundAccurate diagnosis and prompt treatment of pregnancy-associated malaria (PAM) are key aspects in averting adverse pregnancy outcomes. Microscopy is the gold standard in malaria diagnosis, but it has limited detection and availability. When used appropriately, rapid diagnostic tests (RDTs) could be an ideal diagnostic complement to microscopy, due to their ease of use and adequate sensitivity in detecting even sub-microscopic infections. Polymerase chain reaction (PCR) is even more sensitive, but it is mainly used for research purposes. The accuracy and reliability of RDTs in diagnosing PAM was evaluated using microscopy and PCR.MethodsA cohort of pregnant women in north-eastern Tanzania was followed throughout pregnancy for detection of plasmodial infection using venous and placental blood samples evaluated by histidine rich protein 2 (HRP-2) and parasite lactate dehydrogenase (pLDH) based RDTs (Parascreen™) or HRP-2 only (Paracheck Pf® and ParaHIT®f), microscopy and nested Plasmodium species diagnostic PCR.ResultsFrom a cohort of 924 pregnant women who completed the follow up, complete RDT and microscopy data was available for 5,555 blood samples and of these 442 samples were analysed by PCR. Of the 5,555 blood samples, 49 ((proportion and 95% confidence interval) 0.9% [0.7 -1.1]) samples were positive by microscopy and 91 (1.6% [1.3-2.0]) by RDT. Forty-six (50.5% [40.5 - 60.6]) and 45 (49.5% [39.4 – 59.5]) of the RDT positive samples were positive and negative by microscopy, respectively, whereas nineteen (42.2% [29.0 - 56.7]) of the microscopy negative, but RDT positive, samples were positive by PCR. Three (0.05% [0.02 - 0.2]) samples were positive by microscopy but negative by RDT. 351 of the 5,461 samples negative by both RDT and microscopy were tested by PCR and found negative. There was no statistically significant difference between the performances of the different RDTs.ConclusionsMicroscopy underestimated the real burden of malaria during pregnancy and RDTs performed better than microscopy in diagnosing PAM. In areas where intermittent preventive treatment during pregnancy may be abandoned due to low and decreasing malaria risk and instead replaced with active case management, screening with RDT is likely to identify most infections in pregnant women and out-performs microscopy as a diagnostic tool.

Plasmodium falciparumMutant Haplotype Infection during Pregnancy Associated with Reduced Birthweight, Tanzania

“…A prospective cohort of 924 pregnant women was monitored from first attendance at the antenatal clinic through delivery. The study has been described in detail ( 22 – 24 ). In brief, pregnant women with a gestational age of < 24 weeks, as estimated by using ultrasound, were enrolled if they had lived in Korogwe District for > 6 months and were willing to give birth at Korogwe District Hospital.…”

“…Blood smears for women with negative RDT results were examined retrospectively, whereas those for women with positive RDT results were examined immediately if deemed necessary by the study physician for a treatment decision ( 25 ). Parasite density was determined as the number of asexual stage parasites/200 leukocytes (500 leukocytes if <10 parasites) and converted to the number per microliter, as described ( 22 , 25 ); > 100 fields were double-examined before a blood smear was declared negative.…”

“…The DNA supernatant was transferred to a 96-well PCR plate and stored at −20°C until use. The parasite DNA was amplified by outer and nested P. falciparum –specific PCRs, as described ( 27 ); the products were analyzed by electrophoresis in 1.5% ethidium bromide–stained gel, as described ( 22 ). …”

Assessment of labor and delivery in pregnant women on sulfadoxine-pyrimethamine regimen in Yaoundé gynaeco-obstetric and paediatric hospital: a comparative study of 313 cases

“…Positive *RDTm n (%) Negative*RDTm n (%) P-value (15)(16)(17)(18)(19)(20) Table 1 shows the characteristics of women included into the study. The (15-20) age group, single (marital status), lack of financial resources, <4 antenatal visits, the nonuse of mosquito bed nets, the absence of iron prophylaxis and a previous history of malaria crisis during the current pregnancy were associated with malaria infection at the onset of labor.…”

“…Many studies have proven the accuracy of RDTm in the detection of malaria infection, prompting the management thereof with biological evidence. 9,[19][20][21] The presence of clinical signs is not an indicator of the severity of the disease and placental malaria, which is the most common form of malaria in pregnant women, is asymptomatic. 22 Placental malaria could be responsible for adverse outcomes during labor and delivery for both the mother and her fetus.…”