Rapid Finger-Prick Test Reveals High Toxoplasma Burden in Pregnant Ethiopian Women

A simple rapid diagnostic test, deployed for the first time in antenatal clinics in Ethiopia, has revealed that roughly three out of every four pregnant women in the city of Bahir Dar carry antibodies against Toxoplasma gondii, the single-celled parasite that can silently cross the placenta and damage an unborn child. The multicenter cross-sectional study, published in PLOS Neglected Tropical Diseases, enrolled 1,010 women at their first antenatal care visit at two tertiary hospitals and screened them with a commercial immunochromatographic test that detects both IgG and IgM antibodies against the parasite in a single run. The result, a seroprevalence of 75.8 percent, places Bahir Dar among the settings with the highest documented exposure to Toxoplasma in pregnant populations and underscores how much invisible transmission is occurring in a region where routine serological screening has never been part of standard prenatal care.

Toxoplasma gondii is one of the most successful parasites on Earth, capable of infecting virtually all warm-blooded animals, yet most human infections go entirely unnoticed. In a healthy adult, the immune system usually contains the parasite, which then persists in a dormant tissue-cyst form, primarily in muscle and brain tissue. The danger arises when a woman acquires her first infection shortly before or during pregnancy. At that point, before protective antibodies have fully developed, the parasite can spread through the bloodstream, invade the placenta, and infect the fetus. Congenital toxoplasmosis can cause miscarriage, stillbirth, hydrocephalus, chorioretinitis that threatens vision, intracranial calcifications, seizures, and long-term neurodevelopmental impairment. Because primary infection in the mother is typically asymptomatic or produces only mild, flu-like symptoms, the only practical way to identify women at risk is through serological testing, which is precisely what has been missing in much of sub-Saharan Africa.

The research team, led by Yared Mulu Gelaw of Bahir Dar University together with collaborators including Jean-Pierre Gangneux and Florence Robert-Gangneux of Rennes, France, set out to fill that gap using a tool designed for exactly this kind of resource-limited setting. The Toxoplasma ICT IgG-IgM test manufactured by LD Bio is a lateral-flow immunochromatographic assay, the same technological family as the rapid tests familiar from malaria and HIV screening. A small blood sample, applied to the test cassette, migrates along a membrane carrying immobilized antigens; antibodies against Toxoplasma, if present, are captured and visualized as colored lines within minutes. No laboratory infrastructure, electricity, cold chain, or specialized technician is required. The trade-off is that the combined IgG-IgM format indicates whether a woman has ever been infected, but does not by itself distinguish a recent, potentially dangerous primary infection from long-standing, dormant immunity, a limitation the authors acknowledge explicitly.

Study participants were recruited using systematic random sampling among women presenting at less than 20 weeks of gestation, with the average participant enrolled at roughly 14 weeks of pregnancy. The cohort was predominantly urban, with 85.2 percent of women living in city areas, and had a mean age of 26.8 years. The median monthly household income was 5,000 Ethiopian Birr, a figure that situates most families well within the economic constraints that shape diet, hygiene, and access to care. Alongside the blood sample, each woman completed a structured questionnaire covering sociodemographic characteristics, obstetric history, and the dietary and hygienic practices long associated with Toxoplasma transmission, from handling raw meat to consuming unpasteurized dairy. Statistical analysis, performed with binary logistic regression at both bivariable and multivariable levels, then identified which factors independently predicted seropositivity.

The headline number, 75.8 percent seroprevalence, means that only about one in four pregnant women in the cohort lacked antibodies and therefore remained fully susceptible to a primary infection during pregnancy. Seroprevalence rose steadily with both age and parity, an expected pattern for a parasite acquired cumulatively over a lifetime of exposure: each additional year and each additional pregnancy increases the cumulative probability of having encountered Toxoplasma. Notably, the classic socioeconomic gradients often reported elsewhere did not appear here. Educational level, monthly income, occupation, urban versus rural residence, and self-reported hygienic behaviors showed no significant association with seropositivity, suggesting that in this setting the parasite is so widely distributed in the food and environment that wealth and education offer little protection.

What did matter were specific dietary exposures. After adjustment for other variables, women who reported eating undercooked meat had roughly 29 percent higher odds of being seropositive, while those who drank raw milk had 82 percent higher odds, the strongest single risk factor identified in the study. Each additional year of age raised the odds by about 9 percent, and each prior pregnancy by about 33 percent. These findings map cleanly onto the parasite’s known biology. Tissue cysts harboring slowly replicating bradyzoites survive in undercooked beef, lamb, and goat meat, and ingestion of these cysts is one of the two principal routes of human infection worldwide. Raw or unpasteurized milk, particularly from goats, has been implicated in outbreaks of toxoplasmosis and can carry the parasite when animals are actively infected. In a culinary culture where raw meat dishes are traditional and home consumption of unpasteurized dairy is common, these routes of transmission appear to dominate.

The absence of an association with cat ownership or contact deserves attention, because the domestic cat is the definitive host of Toxoplasma and the source of the environmentally resistant oocysts that contaminate soil, water, and vegetables. In this study, hygienic factors generally failed to predict seropositivity, which the authors interpret as evidence that foodborne transmission, rather than direct contact with cats or contaminated soil, is the dominant driver of infection in Bahir Dar. This has practical consequences for prevention. While advising pregnant women to avoid cleaning litter trays remains sensible wherever cats are kept, the far higher-yield interventions here are culinary: cooking meat thoroughly, washing hands and utensils after handling raw meat, and boiling or pasteurizing milk before drinking it.

The choice of screening technology is central to the study’s significance. Conventional serology, whether the Sabin-Feldman dye test, enzyme-linked immunosorbent assays, or chemiluminescence, requires equipped laboratories, trained staff, and reliable supply chains that many antenatal clinics in low-income countries cannot sustain. As a result, Toxoplasma screening during pregnancy is routine in France and several other European countries but essentially nonexistent across most of Africa, leaving the true burden of congenital infection unmeasured. A lateral-flow test that can be performed at the point of care during a first antenatal visit changes that calculus. The authors argue that the ease of use of the Toxoplasma ICT test makes serological screening of pregnant women feasible directly within antenatal care facilities, without referral to distant laboratories. A positive result identifies a woman who has been exposed; a negative result identifies the smaller but clinically crucial group of susceptible women who would benefit most from targeted prevention counseling.

The study does carry limitations that temper interpretation. Because the ICT format reports any Toxoplasma antibody without separately distinguishing IgG from IgM, the 75.8 percent figure represents lifetime exposure rather than the rate of active or recent infection, so it cannot directly estimate how many pregnancies in the cohort were actually threatened by congenital transmission. The cross-sectional design captures a single moment in pregnancy rather than following women forward to birth outcomes, and the reliance on self-reported dietary habits introduces the possibility of recall bias. Nevertheless, as the first application of rapid immunochromatographic screening for Toxoplasma in pregnant women in Ethiopia, the study establishes both a baseline burden estimate and a proof of concept for a screening strategy that could be replicated in other high-burden, low-resource settings.

The public health implications are considerable. With three-quarters of women already immune, universal primary prevention messaging would reach many who no longer need it, while the quarter who remain susceptible face a real and quantifiable risk from two modifiable habits: eating undercooked meat and drinking raw milk. The authors conclude that efforts should focus on raising women’s awareness of these risk factors, particularly the consumption of raw meat and raw milk, and that the operational simplicity of the ICT test opens the door to integrating Toxoplasma serology into routine antenatal care. For a parasite that has historically been invisible to the health systems most exposed to it, a fifteen-minute test at the first prenatal visit may be the beginning of making congenital toxoplasmosis a measurable, and ultimately preventable, problem in Ethiopia.

Subject of Research: Seroprevalence and risk factors of Toxoplasma gondii infection among pregnant women in Bahir Dar, Ethiopia, using rapid immunochromatographic testing

Article Title: First use of rapid ICT screening for Toxoplasma in pregnant women in Ethiopia: A multicenter study in Bahir Dar, Ethiopia

Article References: First use of rapid ICT screening for Toxoplasma in pregnant women in Ethiopia: A multicenter study in Bahir Dar, Ethiopia. (n.d.). https://doi.org/10.1371/journal.pntd.0014616

Image Credits: AI Generated

DOI: 10.1371/journal.pntd.0014616

Keywords: Toxoplasma gondii, toxoplasmosis, pregnancy, seroprevalence, immunochromatographic test, Ethiopia, Bahir Dar, congenital infection, antenatal care, foodborne transmission, raw milk, undercooked meat