In the period 1983-1994 a series of seroepidemiological surveys, by using immunodiagnostic tests for trichinosis, was carried out in 138 localities and health institutions from the 13 regions of the country. Thus, a total of 12,882 randomly selected persons, with different sex and age distribution, were submitted to precipitin test and indirect hemagglutination test for trichinosis. One hundred and ninety one (1.5%) persons resulted positive for trichinosis. Higher rates of infection were observed in central and southern Chile. No differences of positivity, according to age sex, but constant increase parallel to age of the individual were detected. The general prevalence rate of infection of 1.5% is in a reasonable accordance with the prevalence of 2.0% found in human corpses in 1992.

Adolescent↗

PubMedDate not supplied

[Epidemiology of Chagas' disease in Chile. Serological follow-up of 1,906 inhabitants from an endemic rural area, IV Region, 1991-1993].

The IV Region (29 degrees 30'-32 degrees 13' south lat.) is located in the center of the geographical area of distribution of Chagas' disease in Chile. Triatoma infestans is the main and almost exclusive vector of Trypanosoma cruzi in this country. The mean prevalence rate of T. cruzi human infection in urban and periurban sections of IV Region is 24.7%. To assess the impact of anti-T. infestans activities, by means of health education and sprayings of dwellings with insecticides, carried out in the IV Region since 1980, during January-February (summer) a serological follow-up to residents from 46 rural chagasic localities was performed. An indirect hemagglutination test and an indirect immunofluorescence test were done to each of the surveyed persons. In 1991, 303 (15.9%) out of 1,906 examined people resulted serologically positive. In 1992, previous discarding the positive individuals found in 1991, 1,334 persons were examined resulting positive 9 (0.7%). In 1993, 1,398 persons were surveyed and 26 (1.9%) were positive. It is noteworthy that none of these 35 positive persons had been surveyed in 1991, being difficult to assert if any was positive before. Two infants, daughters of positive mothers, serologically positive at the beginning, changed to negative in the following survey, indicating that it was a passive transfer of maternal specific antibodies. According to the results of this study, it is concluded that dwelling spraying with persistent-activity insecticides against T. infestans and health education are good tools in the control of T. cruzi human infection, particularly when the involved community participates.

Adolescent↗

PubMedDate not supplied

[Comparison of the frequency of electrocardiographic changes in groups of apparently healthy persons with a positive serology for Chagas' disease, for toxoplasmosis or for both parasitoses].

In order to compare the frequency of electrocardiographical abnormalities among apparently healthy persons with Trypanosoma cruzi and Toxoplasma gondii infections, electrocardiogram (EKG) and the corresponding indirect hemagglutination tests (IHAT) were performed to 13,444 randomly selected rural and suburban inhabitants from the seven first regions of Chile which are located in the geographic area of distribution of Chagas' disease in the country. The IHAT for each parasitosis resulted positive (titers > or = 1:16) for Chagas' disease alone in 1,289 (9.6%), for toxoplasmosis alone in 3,519 (26.2%) and for the two infections in 994 (7.4%). EKG abnormalities of all type (AAT) and suggestive of a chagasic etiology (ASChE) were found in 18.5 and 8.3% respectively of the T. cruzi infected group, in 10.9 and 3.2% of the T. gondii infected group, in 18.9 and 4.8% of the group simultaneously infected by the two parasites, whereas AAT and ASChE were found in 7.9 and 1.8% of the IHAT negative group. All the corresponding percentage differences between abnormal EKG had a statistical significance (p < 0.05). Besides the increasing of the IHAT positivity, for each infection parallels to the age grouping of the studied persons, a similar situation was observed in the frequence of the AAT and ASChE mainly among people aged > or = 50 years. As T. cruzi and T. gondii infections sometimes isoletely adopt a high virulence and overlap in a proportion higher than 43.0% in Chagas' disease endemic areas, it is advisable to consider these etiologic possibilities in the presence of patients with a myocardiopathy of dubious interpretation, particularly when AIDS is involved.

Adolescent↗

PubMedDate not supplied

[Frequency of electrocardiographic alterations in apparently healthy persons with indirect hemagglutination reaction positive for toxoplasmosis].

An indirect hemagglutination test (IHAT) for toxoplasmosis and electrocardiogram (EKG) were performed to 11,161 apparently healthy inhabitants with negative IHAT for Chagas' disease, from 259 rural and periurban localities sited in the first seven regions of Chile (geographic area of distribution of Chagas' disease in the country). The age of the 11,161 examined people ranged between 5 and 94 years, being 4,518 males and 6,643 females. The IHAT for toxoplasmosis was considered positive with titers > or = 1:16. This test resulted positive in 3,519 (31.1%) persons (30.8% in males and 32.0% in females). Positivity of the IHAT increased from 21.2%, in the youngest group (< 10 years) up to 46.9% in the oldest group (> or = 60 years). Different types of EKG alterations were observed in 10.9% of the IHAT positive individuals and in 7.9% of the IHAT negative ones. In both groups the percentages of altered EKG increased parallel with age. The overall difference of percentages of altered EKG in IHAT positive and IHAT negative persons has a statistical significance with p < 0.001. This study suggest the convenience to consider toxoplasmosis as a cause of chronic myocardiopathy in epidemiological studies on Chagas' disease, because a possible Toxoplasma gondii infection may contribute to overincrease the magnitude of the impact of Trypanosoma cruzi in the generation of the quoted myocardiopathy.

Adolescent↗

PubMedDate not supplied

[Positivity of xenodiagnosis, according to age, in persons with positive serology for Chagas disease].

An analytical study of positive xenodiagnosis (XD), according to age distribution, in people with a positive indirect hemagglutination test (IHAT) for Chagas' disease has been carried out. A total of 1,137 IHAT for Chagas' disease positive persons were submitted to two wooden XD boxes containing 7 Triatoma infestans nymphs III each. The positivity (%) of XD in the different age groups was: 0-9 year-old (60.8), 10-19 (35.8), 20-29 (31.5), 30-39 (28.7), 40-49 (30.0), 50-59 (34.3) and > or = 60 (43.3). The 60.8% positivity of XD in children under 10 years of age is possibly due to the rather recent Trypanosoma cruzi infection in this age group and to diverse immunological mechanisms, which decrease with the age increasing.

Adolescent↗

PubMedDate not supplied

[Chagas disease: impact of Triatoma infestans control program in Alto del Carmen, Huasco Province, III Region Atacama, Chile].

A control program of Triatoma infestans has been carried out in Alto del Carmen, an endemic chagasic rural county in the III Region, Chile. The program started in 1988 with an attack phase consisting in a masshouse spraying with residual insecticide, followed by an entomological surveillance phase with health education for community participation and vector detection in eventually reinfested houses. A yearly evaluation in 1992, 1993, 1994 and 1995 was carried out in order to determine the effectiveness of vector control activities. In 1992, 24.1% of dwellings was infested, whereas in 1993, 1994 and 1995 the infestation rates were 3.9%, 2.8% and 4.0% respectively. The similar infestation rates found in 1993, 1994 and 1995 suggest passive dispersion of triatomas from areas without surveillance. Additionally, in 1994, 110 (16.0%) out of 688 examined people resulted serologically positive. It is noteworthy that all of the children in the 0-4 year age group--born after the attack phase--resulted serologically negative. This fact may indicate the interruption of vectorial transmission of Chagas' disease in Alto del Carmen county. It is concluded that the control activities performed in the county constitute good strategies to the Nacional Program of Control of T. infestans, but for the success of such a program it is necessary to integrate the efforts of all endemic areas with an active community participation.

Adolescent↗

PubMedDate not supplied

[Evaluation of vectors of Chagas' disease eradication programs in Chile by serological study of children under 10 years old].

Chagas' disease is a parasitic zoonosis with high prevalence in Chile. It is distributed in rural and periurban section in the northern most seven out of thirteen regions in which the country is divided, and affects about 142,000 individuals dispersed in most of the 165 counties sited in the chagasic zone. Triatoma infestans--intradomiciliary species--is the main and practically exclusive vector of Trypanosoma cruzi. Diverse tools may be utilized in order to interrupt the domestic cycle of transmission of T. cruzi: health education, housing improvement and elimination of vectors by dwelling insecticide sprayings. This last resource has received priority in Chile in the last 12 years. To evaluate the effectivity of the programs for eliminating T. infestans a serological study for Chagas' disease--comprising 8,767 children less than 10 years old from 27 rural counties insecticide sprayed in the last 12 years--was carried out. A global total of 125 (1.4%) children resulted positive, figure significantly lower than 5.4% found in 1982-1990 in the same age group. Distribution by regions of positive individuals showed a decrease of prevalence in each of them: III Region, from 9.8 to 1.0%, IV Region, 7.2 to 2.0%, V Region, 5.2 to 1.9%, and Metropolitan Region, 1.4% to 0.6. Even though positive children have still been found in 46.7% of localities of the studied counties, it is possible to affirm that the vector control programs have been effective and must be maintained, and increased in those localities with T. cruzi infection in children under 10 years of age, with the general aim of eradicate Chagas' disease transmission in Chile before 2000.

Animals↗

PubMedDate not supplied

[Diagnosis of human neurocysticercosis by ELISA-IgG using a purified antigen].

An analysis of immunodiagnosis data for human neurocysticercosis (NC) by ELISA-IgG, complement fixation test (CFT) and indirect hemagglutination test (IHAT) in 67 serum samples and 54 cerebrospinal fluids (CSF) from confirmed cases of different hospitals from the Metropolitan Area of Santiago, Chile, was performed. The cut-off value was determined by using serum samples from 60 apparently healthy persons, whose absorbance values were the mean plus three standard deviations. The sensitivity of ELISA was 97.0% and 100% for serum samples and CSF respectively. This assay was considered of statistical significance (p < 0.05) when it was compared with CFT. Specificity was established by testing a purified antigen over 109 different helminthiasis serum samples, 185 neurological affections other than NC and 60 control samples. A 98.3% of global specificity was found. The use of ELISA-IgG and a purified antigen in the approach of immune diagnosis of NC is considered a useful assay, particularly if it is performed on paired serum/CSF samples.

Animals↗

PubMedDate not supplied

[Current trends of the epidemiology of human trichinosis in Chile].

Surveillance of the epidemiology of human trichinosis in Chile has been maintained during the last 30 years by the Department of Parasitology. Incidence and prevalence have been followed-up by analysing Ministry of Health annual reports and periodical phototrichinoscopic examination of diaphragm samples from individuals autopsied at the Santiago Medico Legal Service. A decrease has been observed on: incidence from 1.4 per 100,000 in the 1960s to 0.7 in the 1980s down to 0.3 in 1993 and 1994 and to 0.5 in 1995, and prevalence from 3.4% to 2.8%, 2.0% and 0.8% in 1972, 1982, 1992 and 1997 respectively. A predominance of the prevalence in the groups of more age, with the observation of calcified Trichinella spiralis larvae should be indicating a decline of new infections in the general population. This decrease of frequency of human trichinosis in Chile is possible due to the interaction of two main factors, efficacy and higher implementation of control measures and significant advances in porcine technology with a resulting provision to consumers of pork from young animals practically trichinosis free.

Adolescent↗

PubMedDate not supplied

[Immunodiagnosis in 647 suspected clinical cases of toxoplasmosis].

Though Toxoplasma gondii can cause severe pathology in human, in most of the cases it produces only asymptomatic infection. So, it is important to dispose some methods capables to discriminate between acute and chronic infections. An indirect hemagglutination test (IHAT), dye test (DT) and complement fixation test (CFT) were performed in 647 sera from patients suspected of having toxoplasmosis infection. IHAT and DT titer > or = 4 and CFT > or = 5 were considered positive. Titers were classified as follows: low (4-16), median (64-512) and high (> or = 1000) for IHAT and DT. The pathologies for demanding these serological tests were: adenopathies (58), nephropathies (72), neuropathies (30), obstetrical problems (65), opthalmopathies (147), AIDS (237) and miscellaneous (37). Global positivity of 49.5% and 4.5% for IHAT/DT and CFT respectively were found. The positivity for the different groups were: adenopathies (48.3% and 13.8%), nephropathies (43.1% and 1.4%), neuropathies (26.7% and 3.3%), obstetrical problems (40.0% and 0.0%), ophthalmopathies (59.9% and 8.2%), AIDS (52.1% and 2.5%) and miscellaneous (40.5% and 2.7%) for IHAT/DT and CFT respectively. Low and median titers for IHAT/DT were found in 81.3% of cases. A high agreement in frequency of concordant and discordant titers of IHAT/DT and CFT, indicating a recent or acute infection was observed. This fact was more relevant in adenopathies, ophthalmopathies (uveitis) and AIDS groups.

Adolescent↗

PubMedDate not supplied

[Yield of xenodiagnosis and PCR in the evaluation of specific chemotherapy of Chagas' disease in children].

Amplification by the polymerase chain reaction (PCR) of Trypanosoma cruzi kinetoplastic DNA was used to enhance sensitivity in the detection of the parasite in blood, with the ultimate goal of improving the parasitological diagnosis of Chagas' disease in 0-10 year-old infected children. Twenty eight children were evaluated by using xenodiagnosis (XD) and PCR. Whereas XD detected 75.0% of the cases PCR was positive in 96.8%. The usefulness of the PCR was further investigated in the 28 children who have received specific treatment with nifurtimox. Negativation of XD after three and six months post treatment was observed in all the cases, but only 21.4% and 35.8% negativation of the PCR after three and six months post treatment respectively. These observations suggest that PCR is the most sensitive and quick technique available for direct detection of T. cruzi in chagasic children and that it can be a very useful tool for the follow-up of infected subjects after specific chemotherapeutical treatment.

Chagas Disease↗