Estimating malaria burden among pregnant women using data from antenatal care centres in Tanzania: a population-based study

Abstract

Background More timely estimates of malaria prevalence are needed to inform optimal control strategies and measure progress. Since 2014, Tanzania has implemented nationwide malaria screening for all pregnant women within the antenatal care system. We aimed to compare malaria test results during antenatal care to two population-based prevalence surveys in Tanzanian children aged 6-59 months to examine their potential in measuring malaria trends and progress towards elimination.Methods Malaria test results from pregnant women screened at their first antenatal care visits at health-care facilities (private and public) in all 184 districts of Tanzania between Jan 1, 2014, and Dec 31, 2017, were collected from the Health Management Information Systems and District Health Information System 2. We excluded facilities with no recorded antenatal care attendees during the time period. We standardised results to account for testing uptake and weighted them by the timing of two population-based surveys of childhood malaria prevalence done in 2015-16 (Demographic and Health Survey) and 2017 (Malaria Indicator Survey). We assessed regional-level correlation using Spearman's coefficient and assessed the consistency of monthly district-level prevalence ranking using Kendall's correlation coefficient.Findings Correlation between malaria prevalence at antenatal care and among children younger than 5 years was high (r≥0•83 for both surveys), although declines in prevalence at antenatal care were generally smaller than among children. Consistent heterogeneity (p<0•05) in antenatal care prevalence at the district level was evident in all but one region (Kilimanjaro). Data from antenatal care showed declining prevalence in three regions (Arusha, Kilimanjaro, and Manyara) where surveys estimated zero prevalence.Interpretation Routine antenatal care-based screening can be used to assess heterogeneity in transmission at finer resolution than population-based surveys, and provides sample sizes powered to detect changes, notably in areas of low transmission where surveys lack power. Declines in prevalence at antenatal care might lag behind those among children, highlighting the value of monitoring burden and continuing prevention efforts among pregnant women as transmission declines. The pregnancy-specific benefits and cost-effectiveness of antenatal care-based screening remain to be assessed.

Prevalence of malaria parasitaemia in school-aged children and pregnant women in endemic settings of sub-Saharan Africa: A systematic review and meta-analysis

“…In these countries, whilst more than 80% of pregnant women would make at least one ANC visit, their adherence to subsequent visits for the recommended IPTp 3+ policy ( WHO, 2014 ) remains poor ( WHO, 2015 ), with only 24% making their first ANC visit during the first trimester ( Mgata and Maluka, 2019 ; Chimatiro et al, 2018 ). Several studies have suggested pregnant women attending their first ANC could provide data as proxy for malaria transmission or as sentinel population for malaria surveillance ( van Eijk et al, 2015 ; Kitojo et al, 2019 ; Brunner et al, 2019 ). However, the same studies reports some shortfalls in using ANC data such as variation in sensitivity at different endemicities, suggesting ANC data was particularly useful for monitoring in areas approaching elimination ( Kitojo et al, 2019 ).…”

“…Several studies have suggested pregnant women attending their first ANC could provide data as proxy for malaria transmission or as sentinel population for malaria surveillance ( van Eijk et al, 2015 ; Kitojo et al, 2019 ; Brunner et al, 2019 ). However, the same studies reports some shortfalls in using ANC data such as variation in sensitivity at different endemicities, suggesting ANC data was particularly useful for monitoring in areas approaching elimination ( Kitojo et al, 2019 ). Moreover, ANC malaria test-positivity cannot be used to directly predict the prevalence in other population subgroups, where complementary community-level measurements remain highly relevant ( Brunner et al, 2019 ).…”

“…Moreover, ANC malaria test-positivity cannot be used to directly predict the prevalence in other population subgroups, where complementary community-level measurements remain highly relevant ( Brunner et al, 2019 ). Other limitations are typically associated with routine data, such as imperfect reporting and difficult to quantify errors in data collection, transcription, entry, and collation at all levels ( Kitojo et al, 2019 ). In addition, clinics may lack or have frequent stock outs of testing kits hence prioritize testing only patients presenting with symptoms ( Kitojo et al, 2019 ).…”

“…Other limitations are typically associated with routine data, such as imperfect reporting and difficult to quantify errors in data collection, transcription, entry, and collation at all levels ( Kitojo et al, 2019 ). In addition, clinics may lack or have frequent stock outs of testing kits hence prioritize testing only patients presenting with symptoms ( Kitojo et al, 2019 ). Likewise, focusing on pregnant women alone, though less expensive, has in some cases, shown that social mobility of pregnant women may make them non-representative of the referenced testing site or community due to various prevailing social cultural factors ( Moller et al, 2017 ; Atuhaire and Mugisha, 2020 ; Madhi et al, 2018 ).…”

Predictors for the Uptake of Optimal Doses of Sulfadoxine-pyrimethamine for Intermittent Preventive Treatment of Malaria During Pregnancy in Tanzania: Further Analysis of 2015-2016 Tanzania Demographic and Health Survey and Malaria Indicator Survey Data

“…Tanzania is one of the malaria-endemic countries with approximately 1.7 million pregnant women at high risk of malaria infection (8). The trend of malaria prevalence among pregnant women in Tanzania has been uctuating with the highest of 10.3% in 2014 and the lowest of 6.8% in 2017 (9). It was observed that despite the low prevalence of malaria in some areas such as in Zanzibar Island, 0.8% of the pregnant women had malaria parasitemia during delivery (10).…”