Comunicación Breve
Parasitología
Kasmera 47(1):66-69,
Enero-Junio, 2019. ISSN 00755222 E-ISSN
2477-9628
Saúl-García Yotsabeth. Bioanalyses School. Central University of Venezuela. Caracas. Venezuela. E-mail: yotsabeth@gmail.com
Martínez-Leal Coromoto. Instituto Venezolano de los Seguros Sociales “Dr. Rafael Gallardo”. Clinical analysis Lab. Veterinary Faculty. Francisco de Miranda National University. Coro. Venezuela. E-mail: corocoramar@yahoo.com
Semprún-Hernández Neomar. Immunology Lab. Experimental Sciences Faculty. Zulia University. Maracaibo. Venezuela. E-mail: neomar.semprun@gmail.com
Martínez-Méndez
Dilia (Corresponding
Author). Talatona Clinic. International SOS.
Luanda. Angola. Rua S10. Sector de Talatona. Zona CC-B2. Luanda. Angola. Telephone: +34622339081 & +244
936174795. E-mail: dkmartinez.mw@gmail.com
Resumen
Studies
show a high frequency of IgG against T.
gondii. The aim was to evaluate the seroprevalence of IgG and IgM anti-T. gondii in 522 women. 13% of
seropositivity IgG+/IgM- and 0.7% IgG+/IgM+ was found. This could be due to the
climate characteristics who may decrease the transmission. We recommend the
evaluation if the environmental may affect the viability of the oocysts.
Palabras clave: toxoplasmosis;
seroprevalence; IgG & IgM; Toxoplasma gondii; Venezuela
Abstract
Los estudios muestran una alta frecuencia de
IgG contra T. gondii. El objetivo fue evaluar la seroprevalencia de IgG y IgM
anti-T. gondii en 522 mujeres. Se encontró 13% de la seropositividad IgG +/IgM-
y 0,7% IgG+/IgM+. Esta frecuencia podría deberse a las características del
clima. Recomendamos estudiar si el medio ambiente puede afectar la viabilidad
de los ooquistes.
Keywords: toxoplasmosis; seroprevalencia;
IgG e IgM; Toxoplasma gondii; Venezuela
Recibido 04-01-2019 / Aceptado 06-03-2019 / Publicación en línea
19-03-2019
Introducción
Toxoplasmosis is a worldwide parasitic zoonosis
produced by Toxoplasma gondii. In immunocompetent individuals, the
primary infection is usually asymptomatic, but persists in a latent state
throughout life, and can be reactivated in case of immunosuppression (1). The Feline is the
definitive host eliminating oocysts in the feces. The mechanisms of human
infection are the ingestion of oocysts, blood transfusion, organ transplants
and by placental transmission (1-4). Worldwide, the
prevalence of toxoplasmosis is high. In America, around 65% of the population
has detectable levels of total anti-Toxoplasma gondii specific
immunoglobulins, where contact with feces of cats has been shown to be the main
risk factor (2).
In Venezuela, studies conducted in pregnant
women, children and adults at risk (homeless), blood donors and native
populations, show a high frequency of specific IgG against T. gondii (5-14). However, because
it is not a mandatory reporting disease, there is a sub-registration (15). The aim of this study was to evaluate the seroprevalence of
IgG and IgM anti-T.gondii in women of the Coro in 2008 and 2012.
Métodos
Design
and sample: A comparative study was conducted with 2008 and 2012 data. 522 women
from Coro city, randomly selected, participated in the study and a serum sample
were collected.
Ethical
considerations: All women voluntarily accepted their
participation through the signed informed consent. Anonymity and the World
Bioethics Congress guidelines as well as Helsinki declaration were preserved.
Technical
information: IgG
and IgM anti-Toxoplasma gondii detection in 2008 (n=268) was made by the
Microparticle Enzyme Immunoassay (MEIA), using the commercial kit (Toxo IgG and
Toxo IgM, AxSYM®assay Abbott), and in 2012 (n=254) with the Fluorescent
Enzyme-Linked Assay (ELFA), following the protocol of the manufacturer (VIDAS
TOXO IgG and IgM system of bioMerieux®Inc). The reference values of the
commercial kit were considered as a diagnostic. The MEIA kit reference values
for IgG: positive >2.5 IU/ml and lower negative. For IgM: positive >0.600
IU/ml, negative <0.499 IU/ml and indeterminate 0.500-0.599 IU/ml. The ELFA
kit reference values for IgG: positive >8 IU/ml and negative less than 4
IU/ml and indeterminate between 4-8 IU/ml. For IgM: positive >0.65 IU/ml,
negative <0.55 IU/ml and indeterminate 0.55-0.65 IU/ml. Any indeterminate
sample was repeated to confirm the results.
Analysis
of the data: Data
obtained was entered on to an excel spreadsheet and transferred to SPSS version
21 statistical program for the analysis.
Of the 522 women evaluated, seronegative anti-Toxoplasma gondii specificity
IgG-/IgM- were 86% (n=451). 13% (n=65) presented IgG+/IgM-. 1% was IgG-/IgM+
(n=2) and 1% was IgG+/IgM+ (n=4). The seroprevalence by year and specificity
are shown in Table 1. Women who presented
seropositivity to IgM received pharmacological treatment. The distribution
according to the specificity of IgG/IgM antibody is shown in Figure 1.
Table 1. Seroprevalence
of anti-Toxoplasma gondii specificity by year. Coro, Venezuela.
Specificity |
2008 |
2012 |
Total |
|||
n |
% |
n |
% |
N |
% |
|
IgG+/IgM+ |
0 |
0 |
4 |
2 |
4 |
0.7 |
IgG+/IgM- |
38 |
14 |
27 |
10 |
65 |
13 |
IgG-/IgM+ |
1 |
0,3 |
1 |
0,3 |
2 |
0.3 |
IgG-/IgM- |
229 |
85,7 |
222 |
87,7 |
451 |
86 |
Total |
268 |
100 |
254 |
100 |
522 |
100 |
Figure 1. anti-Toxoplasma gondii IgG-IgM specificity
distribution. 2008-2012. Coro. Venezuela
Discusión
Toxoplasmosis is the most widespread parasitic zoonosis
in nature. It has been shown in all latitudes, in humans, more than 300 species
of mammals and around 30 species of birds. It is usually asymptomatic, but it
is responsible for many abortions, fetal, perinatal and infant hazard and is
the most frequent cause of focal infection of the central nervous system in
patients with AIDS, representing a latent threat for all immunosuppressed
patients (2-4).
We found 13% of seropositivity of anti-T
gondii IgG+/IgM-, keeping low thru the years. No statistically significant
variation (p>0.05) during the
follow-up. Positivity both for IgG/IgM was observed only in 0.7% of the 2012
samples, probably a reactivation of a past infection and was 0% on the 2008
samples (Table 1). Our data is in
contradiction of the studies in Venezuela WHO show a high prevalence of
specific IgG/IgM antibodies in urban areas between 32 (5,6) and 61%,
in pregnant women and in individuals at risk (homeless) between 42 and 67% (7-9). In
rural areas it has been reported from 39 to 49% (10). In
native populations: 50% of the Barí of the Sierra de Perijá of Zulia state, 88%
of the Güajiba from the Venezuelan Amazon rainforest and 69% from the Piaroa of
the Bolívar state (11-14). High
prevalence rates are also observed in the rest of the America: Brazil 66%,
Colombia 47%, Mexico 56%, Trinidad and Tobago 39% (16-19). In
Europe, 38% in Croatia (20). In Asia,
42% to 55% in India, Malaysia and Nepal (21,22).
The IgM seroprevalence remained less than 1%
during the years, which shows a very low prevalence of acute infection in this
population (23,24). This
low prevalence is also observed in a small group with no pregnant women in Oman
(25). It also proves that both diagnostic
techniques (ELFA and MEIA) provide good reproducibility of the results and
comparable sensitivity and specificity at the quantitative level of IgG/IgM
specific anti-T. gondii (Fig 1). The specific IgG/IgM reactivity it is
easier to evaluate the stage of the infection since high IgG levels can persist
beyond the year and even low levels can remain in past infections. However, a
low titer may also be the first stage in the ascending curve of IgG in a recent
infection (26,27).
The lower frequency of infection by T. gondii found in this study
comparative with others carried out in the country could be due to the climate
characteristics of the Coro city, with high temperatures (24-34ºC), clay soils
of acidic pH (4,5-5,5) and strong trade alisios winds (28), which probably affect the viability of the
oocysts, decreasing the possibility of transmission.
We recommend keeping the follow-up of the
seroprevalence of infection by T. gondii in Venezuela, with the
evaluation of the risk factors in the infected people and to study if the
environmental characteristics may have consequences of the on the viability of
the oocysts.
To the staff of the laboratories “Virgen
María Auxiliadora” and IVSS "Dr.
Rafael Gallardo” for all the support and Dr. Rosaura Hernández for the
critical review of the manuscript.
The authors declare that they have no financial or personal
relationship(s) that may have inappropriately influenced them in writing this
article.
This study received no funding.
The views expressed in the submitted article are all author´s own and
not an official position of the institution or funder.
Referencias
Bibliográficas