Seroprevalence and risk factors of Toxoplasma gondii among pregnant women in Adwa district, northern Ethiopia

Toxoplasmosis is among the major global zoonotic diseases caused by Toxoplasma gondii (T. gondii) that infect almost all warm-blooded animals including humans [1]. Around 30% of the human population worldwide is chronically infected with T. gondii [2, 3]. The seroprevalence of toxoplasmosis ranged from 10 to 50% in developed countries and over 80% in developing tropical countries [4]. Globally, there are 190,100 new cases of congenital toxoplasmosis; 26, 500 (2/1000 live births) being in the Africa region [5]. Studies conducted in some parts of Ethiopia had also indicated that there was a high seroprevalence of T. gondii (74.73%) infection with higher odds of infection in pregnant women [6].

T. gondii infection causes severe and life threatening consequences in human beings and particularly it is a great health concern to pregnant women and the developing fetus or newborns [7]. In Ethiopia, about 82% women of childbearing age haveimmunity to T. gondii [8]; the rest may be at risk of developing an acute infection if exposed to the parasite. Maternal infection of T. gondii is associated with psychiatric disturbances and poor obstetric outcomes including abortion, still birth and psychomotor retardation. In women, infection was associated with anxiety, depression, schizophrenia spectrum disorders, and suicide attempts [9]. The risk of vertical transmission is lower during the first trimester (15–20%) than the third trimester of maternal infection (60–90%). However, severe fetal disease is associated with the first trimester of maternal infection [10, 11]; an infected fetus may has severe complications such as hearing problems, mental retardation, seizure, Chorioretinitis and hydrocephaly [12‐14].

Changing environmental conditions, whether caused by rapid urbanization, global warming or economic globalization, have already influenced the emergence, transmission and distribution of toxoplasmosis [15]. The ecology of T. gondii, with its complex life-cycle, is susceptible to environmental changes mainly affecting the survival time and infectivity of oocysts, and the behavior and population density of hosts [16]. Giving antibiotic treatment is not the most effective way to prevent congenital toxoplasmosis and associated complications. Primary prevention is best [17]. Besides, clinical diagnosis of toxoplasmosis is difficult, considering that 90 to 95% of the infected pregnant women are asymptomatically infected [18] increasing the risk of congenital infection. Therefore, serological screening of T. gondii infection is essential to prevent the risk of congenital toxoplasmosis. Upon early screening, the use of drugs such as spiramycine was found to prevent congenital infection by more than 60% [2].

Ethiopia is one of the countries with low resources including scarcity of safe drinking water supply particularly in the rural communities; with different domestic animals including cats, dogs, goats, sheep and camel and climatic conditions favoring the survival of the parasite. Considering the above hosts and other predisposing factors for T. gondii, research is needed particularly among pregnant women to depict the prevalence of the parasite. Women engage in different home-based activities such as food preparation and caring their children; they are frequently exposed to domestic animals and garden soil. Hence, screening of pregnant women for T. gondii infection during their Maternal and Child Health (MCH) service is not only of benefit of the women but also benefit the next generation. However, in most parts of Ethiopia, including the study area, there is no continuous screening program for T. gondii because of facility limitations and cases are mostly diagnosed by exclusion. Therefore, the aim of this study was to determine the seroprevalence of T. gondii and its associated factors in Adwa district.

Little was known about the seroprevalence of T. gondii in Tigray region and this is the first report of T. gondii infection in Adwa, Ethiopia. The seroprevalence of T. gondii among pregnant women in the study area was found to be 35.6%. This finding is lower than the findings from Arbaminch, Ethiopia 79.3% [20], Bench Maji, Ethiopia 85.3% [21], Brazil 68.37% [22], Ghana 51.2% [23] but higher than the findings in Tanzania 30.9% [24], Sri Lanka 30.27% [25], China 18.1% [26] and Mexico 11% [27]. The current finding is also lower than the seroprevalence of T. gondii in the lower altitude and higher humidly cities of Kenya, Kisumu (52%) and Mombasa (57%) [28]. Among the seropositive women, the majority of them were found to have a chronic or past infection. However, eleven women (11/128, 8.5%) or 3.1% of the 360 women was found to have a recent infection which is almost comparable to the studies conducted in other regions of Ethiopia [20, 21]. Considering the asymptomatic nature of the disease and the possibility of congenital spread, the serologic finding of this study should not be ignored. This is because the healthcare facilities in the study area lack specific tests for T. gondii; diagnosis is made by exclusion which may result in misdiagnosis or delayed diagnosis.

In this study, different risk factors have been assessed for the seroprevalence of T. gondii. Accordingly, the risk of contracting T. gondii had increased with age of the pregnant women; increased odds of having T. gondii infection was observed in the age group of greater than 24 years as compared to pregnant women in the age group of 15–24 years. This finding is consistent with the studies conducted in Tanzania [24] and Mali [29]. The seroprevalence of T. gondii associated with increasing maternal age might be attributed to the increased risk of contracting infection (7%) for 1 year increase of maternal age [7]. Pregnant women who were unable to read and write were 5.8 times more likely to be infected as compared to those who had at least college education; however, this might be due to lack of awareness of the potential risks, proximity to domestic animals, and gardening. The odds of having T. gondii were 7.7 times higher among pregnant women who rarely wash their hands after contact with garden soil and or domestic animals as compared to those women who always wash their hands. Those pregnant women with a history of contact with a domestic dog and those who used to consume raw vegetables had 12.9 and 6.7 times increased odds of T. gondii infection respectively as compared to their counterparts. In addition, pregnant women who own domestic cat had 5.2 times higher odds of being seropositive for T. gondii. Supporting these findings, contact with garden soil, owing to a domestic dog or cat, and consumption of raw vegetables was significantly associated with T. gondii infection in other studies conducted in Ethiopia [20, 21, 30], China [31], and Brazil [32].

Cats and dogs are thought to be the important amplifiers of infection of T. gondii [33, 34]. In the Ethiopian context, it is common to see domestic cats live and sleep together with human beings. Cats can directly contaminate humans, other animals, and their surrounding through their feces [7]. Likewise, after contact with cat’s feces, dogs can contribute to the transmission of the organism through mechanical contamination of garden soil, vegetables, and human beings. Hence, human beings can possibly acquire the infection or ingest the oocyst of the parasite through their contaminated hands after direct contact with cats or dogs, garden soil, and surfaces or consumption of contaminated vegetables. Oocysts of T. gondii are tough free-living stages of the parasite, and therefore are a major contributor to infections associated with the aforementioned risk factors because they [35]. On the other hand, dogs may acquire the infection from other warm-blooded animals through carnivore contamination, and in turn infect human beings [36].