Prevention of transfusional Trypanosoma cruzi infection in Latin America

Trypanosoma cruzi is a protozoan infection widely spread in Latin America, from Mexico in the north to Argentina and Chile in the south. The second most important way of acquiring the infection is by blood transfusion. Even if most countries of Latin America have law/decree/norms, that make mandatory the screening of blood donors for infectious diseases, including T. cruzi (El Salvador and Nicaragua do not have laws on the subject), there is usually no enforcement or it is very lax. Analysis of published serologic surveys of T. cruzi antibodies in blood donors done in 1993, indicating the number of donors and screening coverage for T. cruzi in ten countries of Central and South America indicated that the probability of receiving a potentially infected transfusion unit in each country varied from 1,096 per 10,000 transfusions in Bolivia, the highest, to 13.02 or 13.86 per 10,000 transfusions in Honduras and Venezuela respectively, where screening coverage was 100%. On the other hand the probability of transmitting a T. cruzi infected unit was 219/10,000 in Bolivia, 24/10,000 in Colombia, 17/10,000 in El Salvador, and around 2-12/10,000 for the seven other countries. Infectivity risks defined as the likelihood of being infected when receiving an infected transfusion unit were assumed to be 20% for T. cruzi. Based on this, estimates of the absolute number of infections induced by transfusion indicated that they were 832, 236, and 875 in Bolivia, Chile and Colombia respectively. In all the other countries varied from seven in Honduras to 85 in El Salvador. Since 1993, the situation has improved. At that time only Honduras and Venezuela screened 100% of donors, while seven countries, Argentina, Colombia, El Salvador, Honduras, Paraguay, Uruguay and Venezuela, did the same in 1996. In Central America, without information from Guatemala, the screening of donors for T. cruzi prevented the transfusion of 1,481 infected units and the potential infection of 300 individuals in 1996. In the same year, in seven countries of South America, the screening prevented the transfusion of 36,017 infected units and 7, 201 potential cases of transfusional infection.

Chagas infection transmission control: situation of transfusional transmission in Brazil and other countries of Latin America

The transmission of the transfusion-associated Chagas disease is an important mechanism of its dissemination in several Latin American countries. The transmission risk depends on five factors: prevalence of infection in blood donors, degree of serological coverage, sensibility of used tests, safety of obtained results and infection risk. The Southern Cone Iniciative set off by the Pan-American Health Organization, in 1991, is contributing to the implementation of blood law in each endemic country, and to reduce the risk of transfusional transmission of this horrible disease. Despite the clear improvement of Brasilian hemotherapy after 1980 (with the creation of the Blood National Program - Pró-Sangue) and the significant reduction of the chagasic infection among its blood donors; socio-economic, politic and cultural unlevels, prevent it from reaching the necessary universality and security. In order to assure both, the Brazilian Ministry of Health decided to restructure its blood system. In May, 1998, a great program was launched, to reach a specific goal: Blood - 100% with quality safety in all its process until 2003. It was divided in 12 projects, intends to guarantee the quality and self sufficiency in blood and hemoderivates.

Redescription of Tejidotaenia appendiculata (Baylis, 1947) (Cestoda: Proteocephalidea), a parasite of Tupinambis teguixin (Sauria: Teiidae) from South America

The species Tejidotaenia appendiculata (Baylis, 1947), a parasite found in teju, Tupinambis teguixin is redescribed and a new diagnosis is provided. The species is characterized by the anterior position of the ovary and the peculiar shape of suckers. It is the first record of this species in Brazil.

Entomological and ecological aspects of six sylvatic species of triatomines (Hemiptera, Reduviidae) from the collection of the National Biodiversity Institute of Costa Rica, Central America

A total of 797 specimens of wild adult triatomines, belonging to six species from the entomological collections of the Costa Rican National Biodiversity Institute, was studied from the standpoint of their relative abundance, as reflected by light traps, distribution in the country, seasonal variations and climatic and altitudinal preferences. Triatoma dimidiata was the most abundant species (32.9% of the total specimens), with a very extensive distribution in different ecological zones, being more common between 100 to 400 m above sea level mainly at the end of the dry season. T. dispar was the third in frequency (21.5%), with narrower distribution, more abundant between 600 to 800 m and scarce during the dry season. Panstrongylus geniculatus and P. rufotuberculatus, second and fourth in frequency (22.1% and 15.1%, respectively), were widely distributed on both the Pacific and Caribbean basins, the former being more common between 80 to 270 m all year round and the latter below 800 m mainly during the first semester. Eratyrus cuspidatus which represented only 4.9% of the insects, was also present on both basins mainly below 200 m with a tendency to be scarce during certain months of the year, and was found in all types of ecological zones. Finally, Rhodnius pallescens, the least abundant species (3.6%) was restricted to very humid areas below 20 m, on the north side and Caribbean basin. With the exception of R. pallescens, males were more commonly found than females. Some epidemiological implications related to the six species are discussed.

The impact of Chagas disease control in Latin America: a review

Discovered in 1909, Chagas disease was progressively shown to be widespread throughout Latin America, affecting millions of rural people with a high impact on morbidity and mortality. With no vaccine or specific treatment available for large-scale public health interventions, the main control strategy relies on prevention of transmission, principally by eliminating the domestic insect vectors and control of transmission by blood transfusion. Vector control activities began in the 1940s, initially by means of housing improvement and then through insecticide spraying following successful field trials in Brazil (Bambui Research Centre), with similar results soon reproduced in São Paulo, Argentina, Venezuela and Chile. But national control programmes only began to be implemented after the 1970s, when technical questions were overcome and the scientific demonstration of the high social impact of Chagas disease was used to encourage political determination in favour of national campaigns (mainly in Brazil). Similarly, large-scale screening of infected blood donors in Latin America only began in the 1980s following the emergence of AIDS. By the end of the last century it became clear that continuous control in contiguous endemic areas could lead to the elimination of the most highly domestic vector populations - especially Triatoma infestans and Rhodnius prolixus - as well as substantial reductions of other widespread species such as T. brasiliensis, T. sordida, and T. dimidiata, leading in turn to interruption of disease transmission to rural people. The social impact of Chagas disease control can now be readily demonstrated by the disappearance of acute cases and of new infections in younger age groups, as well as progressive reductions of mortality and morbidity rates in controlled areas. In economic terms, the cost-benefit relationship between intervention (insecticide spraying, serology in blood banks) and the reduction of Chagas disease (in terms of medical and social care and improved productivity) is highly positive. Effective control of Chagas disease is now seen as an attainable goal that depends primarily on maintaining political will, so that the major constraints involve problems associated with the decentralisation of public health services and the progressive political disinterest in Chagas disease. Counterbalancing this are the political and technical cooperation strategies such as the "Southern Cone Initiative" launched in 1991. This international approach, coordinated by PAHO, has been highly successful, already reaching elimination of Chagas disease transmission in Uruguay, Chile, and large parts of Brazil and Argentina. The Southern Cone Initiative also helped to stimulate control campaigns in other countries of the region (Paraguay, Bolivia, Peru) which have also reached tangible regional successes. This model of international activity has been shown to be feasible and effective, with similar initiatives developed since 1997 in the Andean Region and in Central America. At present, Mexico and the Amazon Region remain as the next major challenges. With consolidation of operational programmes in all endemic countries, the future focus will be on epidemiological surveillance and care of those people already infected. In political terms, the control of Chagas disease in Latin America can be considered, so far, as a victory for international scientific cooperation, but will require continuing political commitment for sustained success.

Redescription of Travassiella avitellina Rego & Pavanelli, 1987 (Proteocephalidea: Monticelliidae, Zygobothriinae), a parasite of Paulicea luetkeni (Siluriformes) from South America

The genus Travassiella Rego & Pavanelli, 1987 comprises only one species, T. avitellina Rego & Pavanelli, 1987; characterized by these authors on the basis of absence of vitelline follicles. In this study, the presence of cortical vitelline follicles in this species is confirmed after de Chambrier and Vaucher (1999); the redescription was performed for the first time based on type and new material collected from Argentina, Brazil and Paraguay. Travassiella is confirmed as a valid genus, and compared to other genera of the subfamily Zygobothriinae. T. avitellina is characterized by: (1) the presence of gland cells posteromedially to suckers; (2) the particular distribution of vitelline follicles, forming lateral arches; (3) uterine primordium cortical, growing into medulla and forming a sac-like uterus; (4) eggs, irregularly oval, outer envelop with excrescences and two digitate lappets in one of the poles.

Prehistoric tuberculosis in America: adding comments to a literature review

Tuberculosis is a prehistoric American human disease. This paper reviews the literature and discusses hypotheses for origins and epidemiological patterns of prehistoric tuberculosis. From the last decades, 24 papers about prehistoric tuberculosis were published and 133 cases were reviewed. In South America most are isolated case studies, contrary to North America where more skeletal series were analyzed. Disease was usually located at the deserts of Chile and Peru, Central Plains in USA, and Lake Ontario in Canada. Skeletal remains represent most of the cases, but 16 mummies have also been described. Thirty individuals had lung disease, 19 of them diagnosed by the ribs. More then 100 individuals had osseous tuberculosis and 26 also had it in other organs. As today, transmission of the infection and establishment of the disease were favored by cultural and life-style changes such as sedentarization, crowding, undernutrition, use of dark and insulated houses, and by the frequency of interpersonal contacts. The papers confirm that despite previous perceptions, tuberculosis seems to have occured in America for millennia. It only had epidemiological expression when special conditions favored its expansion. Occurring as epidemic bursts or low endemic disease, it had differential impact on groups or social segments in America for at least two millennia.

Pfcrt and pfmdr1 alleles associated with chloroquine resistance in Plasmodium falciparum from Guyana, South America

Using DNA extracted from 112 parasitised blood blots, we screened for the population marker of chloroquine resistance (CQR) pfcrt K76T in Plasmodium falciparum infections from Guyana. Pfmdr1 mutations S1034C, N1042D, and D1246Y also associated with CQR were surveyed as well in 15 isolates for which the in vitro responses to CQ were known. Results indicate that the pfcrt K76T is ubiquitous in this environment, and confirmatory sequencing of codons 72 and 76 revealed two novel allelic sequences SVMIT and RVMNT in addition to the previously identified CVMNT and SVMNT haplotypes. The frequency of the pfcrt K76T despite its presence in both CQR and CQS (chloroquine sensitive) infections measured in vivo and in vitro, suggests that it is a useful population marker in this low-transmission setting of sweeping CQR.

Antimicrobial susceptibility patterns of unusual nonfermentative gram-negative bacilli isolated from Latin America: report from the SENTRY Antimicrobial Surveillance Program (1997-2002)

The antimicrobial susceptibility of 176 unusual non-fermentative gram-negative bacilli (NF-GNB) collected from Latin America region through the SENTRY Program between 1997 and 2002 was evaluated by broth microdilution according to the National Committee for Clinical Laboratory Standards (NCCLS) recommendations. Nearly 74% of the NF-BGN belonged to the following genera/species: Burkholderia spp. (83), Achromobacter spp. (25), Ralstonia pickettii (16), Alcaligenes spp. (12), and Cryseobacterium spp. (12). Generally, trimethoprim/sulfamethoxazole (MIC50, < 0.5 µg/ml) was the most potent drug followed by levofloxacin (MIC50, 0.5 µg/ml), and gatifloxacin (MIC50, 1 µg/ml). The highest susceptibility rates were observed for levofloxacin (78.3%), gatifloxacin (75.6%), and meropenem (72.6%). Ceftazidime (MIC50, 4 µg/ml; 83.1% susceptible) was the most active beta-lactam against B. cepacia. Against Achromobacter spp. isolates, meropenem (MIC50, 0.25 µg/ml; 88% susceptible) was more active than imipenem (MIC50, 2 µg/ml). Cefepime (MIC50, 2 µg/ml; 81.3% susceptible), and imipenem (MIC50, 2 µg/ml; 81.3% susceptible) were more active than ceftazidime (MIC50, >16 µg/ml; 18.8% susceptible) and meropenem (MIC50, 8 µg/ml; 50% susceptible) against Ralstonia pickettii. Since selection of the most appropriate antimicrobial agents for testing and reporting has not been established by the NCCLS for many of NF-GNB species, results from large multicenter studies may help to guide the best empiric therapy.

Increased resistance to first-line agents among bacterial pathogens isolated from urinary tract infections in Latin America: time for local guidelines?

Emerging resistance phenotypes and antimicrobial resistance rates among pathogens recovered from community-acquired urinary tract infections (CA-UTI) is an increasing problem in specific regions, limiting therapeutic options. As part of the SENTRY Antimicrobial Surveillance Program, a total of 611 isolates were collected in 2003 from patients with CA-UTI presenting at Latin American medical centers. Each strain was tested in a central laboratory using Clinical Laboratory Standard Institute (CLSI) broth microdilution methods with appropriate controls. Escherichia coli was the leading pathogen (66%), followed by Klebsiella spp. (7%), Proteus mirabilis (6.4%), Enterococcus spp. (5.6%), and Pseudomonas aeruginosa (4.6%). Surprisingly high resistance rates were recorded for E. coli against first-line orally administered agents for CA-UTI, such as ampicillin (53.6%), TMP/SMX (40.4%), ciprofloxacin (21.6%), and gatifloxacin (17.1%). Decreased susceptibility rates to TMP/SMX and ciprofloxacin were also documented for Klebsiella spp. (79.1 and 81.4%, respectively), and P. mirabilis (71.8 and 84.6%, respectively). For Enterococcus spp., susceptibility rates to ampicillin, chloramphenicol, ciprofloxacin, and vancomycin were 88.2, 85.3, 55.9, and 97.1%, respectively. High-level resistance to gentamicin was detected in 24% of Enterococcus spp. Bacteria isolated from patients with CA-UTI in Latin America showed limited susceptibility to orally administered antimicrobials, especially for TMP/SMX and fluoroquinolones. Our results highlight the need for developing specific CA-UTI guidelines in geographic regions where elevated resistance to new and old compounds may influence prescribing decisions.

Current situation of Chagas disease in Central America

Chagas disease in Central America is known since 1913 when the first human case was reported in El Salvador. The other Central American countries reported their first cases between 1933 and 1967. On October 1997 was launched the Central American Initiative for Chagas Disease Control (IPCA). The objectives of this sub-regional Initiative are: (1) the elimination of Rhodnius prolixus in Central America; (2) the reduction of the domiciliary infestation of Triatoma dimidiata; and (3) the elimination of the transfusion transmission of Trypanosoma cruzi. Significant advancements being close to the elimination of R. prolixus in Central America and the control of the transfusion transmission has been a transcendent achievement for the sub-region. The main challenges that the IPCA will have in the close future are: developing effective strategies for control and surveillance of T. dimidiata; and surveillance of other emerging triatominae species like R. pallescens, T. nitida, and T. ryckmani.