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Revista da Sociedade Br asileir a de Medicina Tr opical 3 8 ( 4 ) :3 5 8 -3 6 0 , jul-ago, 2 0 0 5
COMUNICAÇÃO/COMMUNICATION
An estimation of the frequency of gestational toxoplasmosis
in the Brazilian Federal District
Contribuição para a estimativa da freqüência de toxoplasmose
em gestantes do Distrito Federal
Otávio de Tolêdo Nóbrega
1,2and Margô Gomes de Oliveira Karnikowski
1,2ABSTRACT
Ac u te i n f e c ti o n s b y th e p ro to zo a n Toxoplasma gondii d u ri n g p re gn a n c y ( ge sta ti o n a l to x o p la sm o si s) a re k n o wn to c a u se se ri o u s h e a lth p ro b le m s to th e f e tu s ( c o n ge n i ta l to x o p la sm o si s) . In Bra sí li a , th e re h a ve b e e n f e w stu d i e s o n th e i n c i d e n c e o f to x o p la sm o si s. Th i s re p o rt su m m a ri ze s a re tro sp e c ti ve stu d y p e rf o rm e d o n 2 ,6 3 6 se le c te d p re gn a n t wo m e n a tte n d e d b y th e p u b li c h e a lth syste m o f Gu a rá , a sa te lli te - Ci ty o f Bra sí li a . In th i s su rve y, 1 7 c a se s o f ge sta ti o n a l to x o p la sm o si s we re de te c te d; 15 o f whi c h we re pri m a ry m a te rn a l i n f e c ti o n a n d the re m a i n i n g 2 we re c o n si ste n t wi th se c o n da ry m a te rn a l i n f e c ti o n . Th e se re su lts su gge st a n a n n u a l se ro c o n ve rsi o n ra te o f 0 .6 4 p e rc e n t ( 9 0 p e rc e n t c o n f i d e n c e i n te rva l: 0 .3 8 , 0 .9 0 ) .
Ke y-words:Toxoplasma. Ge sta ti o n a l to x o p la sm o si s. Mo rb i d i ty. Fe d e ra l Di stri c t. Bra zi l.
RESUMO
In f e c ç õ e s a gu d a s p e lo p ro to zo á ri o Toxoplasma gondii d u ra n te a gra vi d e z ( to x o p la sm o se e m ge sta n te s) sã o c o n h e c i d a s p o r c a u sa r sé ri o s p ro b le m a s d e sa ú d e a o f e to ( to x o p la sm o se c o n gê n i ta ) . Em Bra sí li a , e stu d o s so b re a i n c i d ê n c i a d a to x o p la sm o se sã o e sc a sso s. Este re la to re su m e u m e stu d o re tro sp e c ti vo re a li za d o c o m u m gru p o se le c i o n a d o d e 2 .6 3 6 ge sta n te s a ssi sti d a s p e lo si ste m a p ú b li c o d e sa ú d e d o Gu a rá , Ci d a d e - sa té li te d e Bra sí li a . Ne sta i n ve sti ga ç ã o , f o ra m d e te c ta d o s 1 7 c a so s d e to x o p la sm o se ge sta c i o n a l; 1 5 d o s q u a i s c a so s d e i n f e c ç ã o m a te rn a p ri m á ri a , e o s 2 re sta n te s c o n si ste n te s c o m i n f e c ç ã o m a te rn a se c u n d á ri a . Este s re su lta d o s su ge re m u m a ta x a d e so ro c o n ve rsã o a n u a l d a o rd e m d e 0 ,6 4 p o rc e n to ( i n te rva lo d e c o n f i a n ç a d e 9 0 p o rc e n to : 0 ,3 8 ; 0 ,9 0 ) .
Pal avr as-chave s: Toxoplasma. To x o p la sm o se ge sta c i o n a l. Mo rb i d a d e . Di stri to Fe d e ra l. Bra si l.
1 . Center for Studies in Health Sc ienc es at the University of B rasília, B rasília, DF, B razil. 2 . Pharmac y College at the Catholic University of B rasília, B rasília, DF, B razil.
Addr e ss to: Dr. Otávio de T. Nó brega. Pró -Reito ria de Graduaç ão /Curso de Farmác ia. Q.S. 0 7 , Lo te 0 1 , EPCT, Águas Claras, 7 2 0 3 0 -1 7 0 B rasília, DF, B rasil. Tel: 5 5 6 1 3 5 6 -9 6 9 3 , Fax: 5 5 6 1 3 5 6 -3 0 1 0 .
e-mail: no brega@ po s.uc b.br. Rec ebido para public aç ão em 7 /1 /2 0 0 4 Ac eito em 8 /5 /2 0 0 5
Toxoplasmosis is caused by infection with the protozoan parasite To xo pla sm a go ndii. Acute infections acquired during pregnanc y ( gestational toxoplasmosis) are known to c ause serious health problems when the microorganism is transmitted to the fetus ( c o ngenital to xo plasmo sis) , inc luding o c ular and neuro lo gic al sequels, seizures, blindness and death1. Nonetheless, manifestations of congenital toxoplasmosis may not become apparent until the second or third decades of life2. In Brazil, offic ial statistic s from the Ministry of Health (http:// ta b n e t. d a ta s u s . go v. b r / c gi / s i m / o b tm a p . h tm) s ta te th a t toxoplasmosis alone is responsible for on average 9 0 deaths a year. However, there is a lack of data on the morbidity posed by
this zoonosis. Several studies ( reviewed by Camargo)1 have shown that 5 0 to 8 0 % of all Brazilian women in childbearing age exhibit IgG antibodies to T. go ndii. Therefore, 2 0 to 5 0 % are susceptible to this infection. In various states of the Country, serological sur ve ys have c o nfir me d ste ady r ate s o f infe c tio n dur ing pregnancy: for instance 1 .7 % and 1 .8 % in the states of Santa Catarina2 and Paraná, respectively5.
3 5 9 Nó br e ga OT a nd Ka r niko wski MGO
number of cases notified in that area, that totaled 4 6 cases in the first semester of year 2 0 0 0 (http://www.sa ude .df.go v.b r/sa ude / 11no t11b .a sp) . Unfortunately, cases of congenital or gestational toxoplasmosis are not c urrently assessed. In this sc enario, elaborating epidemiologic surveys and determining expectancy rates might aid in the implantation of targeted prenatal education and newborn screening strategies with the goal of preventing morbidity associated with the disease.
In this report, we present results of a pilot study that provided an estimation of the frequency of gestational toxoplasmosis in the satellite-city of Guará, located within the geo-economical limits of the B razilian Federal Distric t. For that purpose, a retrospective study was performed investigating serologic records of pregnant women admitted from January to December 2 0 0 0 in prenatal programs of the public regional hospital of Guará ( HRGu) and the 3 public health c enters o f that c ity. This investigation was conducted by screening individual medical records for indication of gestational toxoplasmosis among the women studied. Taking into account that: i) most women are submitted to prenatal tests for toxoplasma-specific IgG and IgM whenever admitted to prenatal follow up, and those susceptible are re-tested on a bimonthly basis, and ii) the diagnostic procedures for toxoplasmosis in the regional public health system are standardized, using enzyme-linked immunosorbent assay ( ELISA) as described by Camargo1, a total of 2 ,6 3 6 pregnancies were selected that presented IgM and IgG levels < 1 :6 4 .
Infec tion during pregnanc y was identified based on the o c c ur r e nc e o f mate r nal se r o c o nve r sio n ac c o r ding to the following independent criteria: 1) detection of specific IgM in dilutions
≥
1 :6 4 , or 2) a minimum four-fold rise in the specific IgG levels in comparison with the titer stated on the woman’s former test. For this study, a c ase was c onsidered positive whenever a following c onfirmatory test ( i.e. repetition) was present in the woman’s record. Considering the group studied, the criteria above are consistent with active toxoplasmosis1 6, characterizing primary and secondary gestational toxoplasmosis, respectively. Statistical analysis was performed determining the c onfidenc e interval for eac h estimation, setting the level of confidence at 9 0 percent ( z = 1 .6 5 ) .B ase d o n the ab o ve c r ite r ia, 1 7 c ase s o f ge statio nal toxoplasmosis were found within the universe of pregnancies studied, of which 1 5 were diagnosed by specific IgM antibodies against T. go ndii, amounting to 0 .5 7 % ( 9 0 % confidence interval ( CI) : 0 .3 4 , 0 .8 0 ) o f primary maternal infec tio n. The two remaining cases were diagnosed by the four-fold IgG increase criterion, giving 0 .0 8 % ( 9 0 % CI: 0 .0 1 , 0 .1 5 ) secondary maternal infec tio n. Taken to gether, these results suggest an o verall seroconversion rate of 0 .6 4 percent ( 9 0 % CI: 0 .3 8 , 0 .9 0 ) . The data above is summarized in Table 1 . As this was a preliminary study, the influence of factors such as age, ethnicity or social-economical group were not considered.
In summary, our results reveal that the frequency of primary to xo plasma infec tio n amo ng pregnant wo men ( 0 .5 7 % ) is relatively low in our region when compared to states such as Santa Catarina ( 1 .7 percent) and Paraná ( 1 .8 percent) , this being nonetheless noteworthy, sinc e it signific antly e xc e e de d the
frequenc y of sec ondary infec tion (P < 0 .0 0 1 ) and ac c ounted for 8 8 .2 % of the seroc onversion oc c urrenc es identified in the present study.
Although our results do not allow precise determination of the prevalence of congenital toxoplasmosis, expectancy rates are usually helpful for implementing public health policies for infectious diseases. Taking into account that 4 6 ,5 0 0 live newborns were delivered at the capital’s public health system in the year 2 0 0 0 (http:// www.sa ude .df.go v.b r/do wnlo a d/da do s_ e sta tistic o s.zip) , the incidence of primary maternal infection was extrapolated to estimate a frequency of gestational toxoplasmosis raging from 3.4 to 8 per 1,000 live births that year. It is important to consider that 80% of all cases of primary toxoplasmosis in pregnancy result in ocular lesion or late neurological disorders in the child2. Therefore, our results suggest a yearly average of 2 1 2 children at risk for developing s e q ue ls fr o m pr im a r y m a te r n a l to xo pla s m a in fe c tio n . Unfortunately, our estimation probably underestimates the total number of newborns carrying the congenital form of the disease in Brasília, since this work was based on data from the public health system only, without considering pregnancies attended by the regional private health system. In addition, a stringent cut-off limit was set in order to minimize inclusion of false-positive cases or borderline results. Furthermore, even though a social-economical analysis was not included, it should be considered that the city of Guará may not accurately represent the entire Federal District, since the outskirts are generally recognized to have lo wer standards o f sanitary infrastruc ture. Future assessments on the seroconversion rate among pregnant women resident in such areas would help increase the accuracy of the estimation determined in this study, which may feature from now on as a referential index on the status of the toxoplasmosis issue in the Brazilian Federal District and in Brazil as a whole.
The incidence of gestational toxoplasmosis varies greatly between regions, but is rec ognized to be widely distributed throughout the globe. The practice of routine serologic screening for maternal toxoplasma infection in countries such as France and Austria has proven to greatly reduce the incidence of the congenital form of the disease6. In Brazil, such practice is not generally implemented, due in part from failure to enforce legal obligations. Consequently much data on the incidence of toxoplasmosis is unavailable. Such a lack of screening for onset of congenital toxoplasmosis predisposes countless newborns throughout the Country to development of late consequences, which could have been minimized by an early postnatal intervention.
Table 1 - Individual cases of gestational toxoplasmosis ( absolute number) an d se r ocon ve r sion r ate s ( pe r ce n tage ) for pr im ar y an d se con dar y in fection s fou n d am on g the 2,636 pregn an cies stu died.
Index/Status Cases Seroconversion rate
Primary infection 15 0.57%
( 90% CI: 0.34, 0.80)
Secondary infection 2 0.08%
( 90% CI: 0.01, 0.15)
Total 17 0.64%
( 90% CI: 0.38, 0.90)
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Revista da Sociedade Br asileir a de Medicina Tr opical 3 8 ( 4 ) :3 5 8 -3 6 0 , jul-ago, 2 0 0 5
ACKNOWLEDGEMENTS
The authors are greatly indebted to Dr. Rosane Santos Gr iso lia, fr o m the Regio nal Lab o r ato r y o f Guar á, fo r her advisory role on tec hnic al issues and interpretation of results. The authors also thank the University of B rasília for assistanc e in the development of this study.
REFERENCES
1 . Camargo ME. To xo plasmo sis. In: Ferreira AW, Ávila SLM ( eds) Diagnóstic o labo rato rial das princ ipais do enç as infec c io sas e auto -imunes, Edito ra Guanabara-Ko o gan, Rio de Janeiro , p. 1 6 5 -1 7 4 , 1 9 9 6 .
2 . Ca n to s GA, Pr a n do MD, Siq ue ir a MV, Te ix e ir a R M. To x o pla s m o s e : o c o rrênc ia de antic o rpo s anti-To x o p la sm a go n d i i e diagnó stic o . Revista da Asso c iaç ão Médic a B rasileira 4 6 : 3 3 5 -3 4 1 , 2 0 0 0 .
3 . Jones JL, Lopez A, Wilson M, Sc hulkin J, Gibbs R. Congenital toxoplasmosis: a review. Obstetric al and Gynec o lo gic al Survey 5 6 : 2 9 6 -3 0 5 , 2 0 0 1 .
4 . Ko ppe JG, Lo e we r SDH, Ro e ve r B H. Re sults o f 2 0 ye ar s fo llo w-up o n c o ngenital to xo plasmo sis. Lanc et 1 : 2 5 4 -2 5 6 , 1 9 8 6 .
5 . Reic he EMV, Mo rino to HK, Farias GN, Hisatsugu KR, Geller L, Go mes ACLF, I n o ue HY, Ro dr igue s G, Ma ts uo T. Pr e va lê n c ia de tr ipa n o s s o m ía s e ame r ic ana, sífilis, to xo plasmo se , r ub é o la, he patite B , he patite C e da infec ç ão pelo vírus da imuno defic iênc ia humana, avaliada po r intermédio de testes so ro ló gic o s, em gestantes atendidas no perío do de 1 9 9 6 a 1 9 9 8 no Ho spital Universitário Regio nal No rte do Paraná. Revista da So c iedade B rasileira de Medic ina Tro pic al 3 3 : 5 1 9 -5 2 7 , 2 0 0 0 .
