Congenital Toxoplasmosis in Humans and Domestic Animals

Katia Denise Saraiva Bresciani, Alvimar José da Costa, Katia Denise Saraiva Bresciani, Alvimar José da Costa

• Publisher: Bentham Science Publishers
• Year: 2018
• Print ISBN:
  9781681086446
• eBook ISBN:
  9781681086439
• Topic: Medicine
• Subtopic: Infectious Diseases

Congenital Toxoplasmosis in Humans and Domestic Animals presents information about Toxoplasma gondii and its infection in neonates and different animals cats, cattle, dogs, goats, pigs and sheep. Readers will have quick access to the pathophysiology, di

Human Congenital Toxoplasmosis

Italmar T. Navarro^{1, *}, Regina Mitsuka–Breganó¹, Selwyn A. Headley¹, Jaqueline D. Capobiango², Inacio T. Inoue², Antonio M.B. Casella², Edna M.V. Reiche², Fabiana M.R. Lopes Mori³

¹ Centro de Ciências Agrárias, Universidade Estadual de Londrina, Paraná, Brazil

² Centro de Ciências Saúde, Universidade Estadual de Londrina, Paraná, Brazil

³ Centro de Ciências Saúde, Centro Universitário Filadélfia, Londrina, Paraná, Brazil

Abstract

Notwithstanding, the severity of the sequels and the frequency of occurrence, congenital toxoplasmosis in humans continues to be a neglected disease in several countries, including Brazil. This is partly because a large proportion of infected children are asymptomatic at birth, and consequently are not diagnosed and treated during the first year of life, while most develop ocular and neuro–psycho–motor sequels in early adulthood. The disparity of several management protocols for acute toxoplasmosis has resulted in extreme difficulty for the physicians to make decisions, resulting in many patients being subjected to unnecessary therapies and invasive procedures or are not treated adequately. Another great difficulty lies with the diagnosis, since most pregnant women are asymptomatic when infected, while diagnosis is based on laboratory results, whose interpretation is dependent on several factors, including screening and confirmatory tests and the gestational age when blood sample was taken. Another difficulty is related with the post–natal diagnosis, because in many neonates, it is not possible to detect specific IgM antibodies, and the presence of IgG does not confirm an infection, since these can be passively transferred from the mother to the infant. Faced with this dilemma and based on the work of our group with patients, communities, health services, this team of specialists have accumulated widespread knowledge for the elaboration and implementation of the “Health surveillance program of gestational and congenital toxoplasmosis in Londrina, Paraná, Southern Brazil”. This successful program has served as the basis for this chapter.

Keywords: Clinical aspects, Epidemiology, Maternal screening, Molecular diagnosis, Neonatal screening, Ocular toxoplasmosis, Prevention, Risk factors, Surveillance program, Toxoplasma gondii, Transmission, Treatment.

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^* Corresponding author Italmar T. Navarro: Centro de Ciências Agrárias, Universidade Estadual de Londrina, Paraná, Brazil; Tel/Fax: [phone]; E-mail: [email protected]

EPIDEMIOLOGY AND THE IMPACT OF CONGENITAL TOXOPLASMOSIS

Although T. gondii occurs worldwide, the prevalence of infection is greater in the tropics than in other regions and is reduced as the latitude increases. It is well established that there are several sources of infection of T. gondii and that these vary from region to region, hence it is important to identify the factors that are more associated with infection [1]. The possibility of being exposed to the sources of infection is determined by the socioeconomic and cultural conditions, including the practices of food production, water treatment, hygiene, food habits, exposure to soil, and the climate of the region [2]. Consequently, the knowledge of these factors is important to control strategies efficiently [3].

The prevalence of toxoplasmosis in pregnant women varies in each geographical region: being 0.8% in Korea [4], 10.6% in China [5], 34.1% in Sudan [6], and 75.2% in the Democratic Republic of St. Thomas and Principe [7]. A study conducted in the USA revealed a prevalence of 14.9% among 2,221 pregnant women [8]. In Mexico, the prevalence is considered as low, varying between 6.1 and 8.2% in the city of Durango [9, 10]. In Austria, a prevalence of 36% was identified [11], while the positivity observed in Slovenia was 34% of 21,270 pregnant women [12].

A reduction (from 84% in 1960 to 44% in 2003) in the prevalence of toxoplasmosis in pregnant women was observed in France and this phenomenon was attributed to several factors, such as improved socioeconomic levels, hygienic conditions, better sanitary conditions for animal rearing, feeding of cats with commercial food, and the ingestion of frozen meat. In 2007, 31 laboratories identified at least one case of congenital toxoplasmosis (CT) with the surveillance system from a total of 271 cases. The general prevalence of CT in that year was 3.3 for each 10,000 children born alive [13].

The prevalence of CT in pregnant women in Brazil varied from 31% in Caxias do Sul, Rio Grande do Sul, South, to 91.6% in the State of Mato Grosso do Sul, in the Midwest [14, 15]. Nevertheless, studies that have evaluated the risk associated with the transmission of toxoplasmosis in the different geographical regions of Brazil are scarce [16]. Forty-seven confirmed cases of CT due to the identification of specific IgM anti-T. gondii antibodies from 140,000 neonatal blood samples collected on filter paper from several Brazilian cities were described, with an estimated incidence of 1: 3,000 live neonates [17].

A study with 1,250 pregnant women from the State of Rio Grande do Sul, showed that the prevalence of IgG (48.5%) and IgM (0.6%) anti-T. gondii antibodies and a rate of transmission of 2.2 in 1,000 live neonates [18]. Another study that evaluated 2,126 pregnant women from the Basic Health System at the Northeastern region of the same State, reported that 74.5% (1,583) were positive to IgG anti-T. gondii antibodies, while 3.6% (77) of these samples contained specific IgM anti-T. gondii antibodies. Additionally, from the 51 children that were followed up to one-year of age, 50 were asymptomatic, three were congenitally infected according to the serological profile, while one of these had ophthalmic lesions and cerebral calcifications [19].

A study that evaluated 522 seronegative pregnant women for T. gondii from Goiâna, Goiás, Midwestern Brazil, described a seroconversion rate of 8.6% (45/522). Seroconversion occurred during the second trimester of pregnancy and the estimated fetal infection was calculated as 34.5: 1,000. These authors revealed that it was the most elevated rate of maternal seroconversion registered in the published literature and highlighted the need for primary and secondary prevention in pregnant women that are at risk [20].

Pregnant women that were attended by the Basic Health Units in Londrina, Paraná, Southern Brazil, demonstrated the seroprevalence of anti-T. gondii IgG (49.2%) and IgM (1.2%) antibodies. The age of the pregnant women, per capita salary, educational level, presence of a cat in the residence, and the habit of eating raw vegetables were more frequently associated with the risk of acquiring toxoplasmosis. Alternatively, it was also demonstrated that the ingestion of crude or not fully cooked meat and contact with soil were not associated with the possibility of having toxoplasmosis [21].

In addition, a study that evaluated pregnant women from two cities located at the Western region of the State of Paraná, that were attended by Public Health Service, revealed a prevalence of IgG antibodies of 59.8% in Palotina and 60.6% in Jesuítas [22].

In summary, CT produces an important socioeconomic impact, particularly if the affected infant suffers from mental disability and blindness. In the USA, it is estimated that each year almost 3,000 children are born with CT and that the annual costs associated with the care of these infants varies between 31 - 40 million USD [23].

If the prevalence of the infection is further reduced, the number of seronegative pregnant women is reported higher and therefore there are more pregnant women at a risk of primary infection. However, under this scenario, the level of environmental parasites is also low, resulting in a reduced risk of infection during gestation [2...

Table of contents

• Welcome
• Table of Contents
• Title
• BENTHAM SCIENCE PUBLISHERS LTD.
• FOREWORD
• PREFACE
• BIOGRAPHY
• DEDICATION
• SUMMARY
• List of Contributors
• Toxoplasma gondii
• Human Congenital Toxoplasmosis
• Congenital Toxoplasmosis in Dogs
• Congenital Toxoplasmosis in Cats
• Congenital Toxoplasmosis in Ewes
• Congenital Toxoplasmosis in Pigs
• Congenital Toxoplasmosis in Goats
• Congenital Toxoplasmosis in Cattle