Molecular characterization of Trypanosoma cruzi and Leishmania spp. coinfection in mammals of Venezuelan coendemic areas

BACKGROUND & OBJECTIVES

Trypanosoma cruzi and Leishmania spp. are protozoans that cause American trypanosomiasis and leishmaniasis, respectively. In endemic foci where both diseases coincide, coinfection can occur. The objective of this work was the characterization of the parasites involved in coinfection in several endemic areas of Venezuela.

METHODS

Molecular characterization was done in 30 samples of several species of mammals (Didelphis marsupialis, Equus mulus, Rattus rattus, Canis familiaris, Felis catus, and Sciurus granatensis) from the states of Anzoategui, Cojedes and Capital District diagnosed with T. cruzi and Leishmania spp. coinfections. For the typing of T. cruzi DTUs, the markers of miniexon, 24Sa rDNA, 18Sa rDNA, and hsp60-PCR-RFLP (EcoRV) were used. Infection by Leishmania spp. was characterized by miniexon multiplex PCR for complexes of Leishmania and ITS1-PCR-RFLP (HaeIII, HhaI, and RsaI) for the identification of the species.

RESULTS

The T. cruzi TcI was present in 100% of the coinfected mammals, which included 76.7% of triple infection by T. cruzi TcI-complex-L. (L) mexicana-L. infantum/chagasi, 13.3% of double infection by T. cruzi TcI-L. mexicana and 10% of double infection by T. cruzi Tcl-L. infantum/chagasi.

INTERPRETATION & CONCLUSION

These results suggest that the double or triple infection is a phenomenon existing in almost all the coendemics areas and mammals studied, which might influence the mechanisms of adaptation and pathogenicity of these parasites.

Diagnosis of Taeniosis in rural Venezuelan communities: Preliminary characterization of a Taenia solium specific monoclonal (VP-1) Coproantigen ELISA

The objective of this study was to identify and treat carriers of adult Taenia solium present in two rural Venezuelan communities through examination of faecal samples by coproscopical analysis, and by the application of a polyclonal and a monoclonal (VP-1) coproantigen ELISA. Both the polyclonal and monoclonal ELISA's were negative when tested with soluble extracts of adults of Ascaris lumbricoides, Hymenolepis nana and Trichuris trichura. The polyclonal ELISA was positive for soluble extracts adults of T. solium and T. saginata, whereas the monoclonal ELISA, which recognizes a glycoprotein, was restricted to T. solium, and was also negative with faecal samples from five cases of T. saginata adult infections. In the first community studied, Potrero Largo (Total population: 300), of 248 faecal samples examined, 2 individuals were positive for Taenia spp eggs by coproscopical analysis and the VP-1 ELISA, and yielded T. solium adults upon purging. In contrast, when the polyclonal coproAg ELISA was applied to the same 248 faecal samples, there were a considerable number of positives. Indeed, seven patients highly positive in the polyclonal ELISA did not yield a Taenia spp upon purging and were negative in the VP-1 ELISA. In the second community studied La Yuca (Total population 560), none of the 333 individuals who donated faeces was positive for Taenia spp eggs. Many, however, were infected with a range of intestinal helminth and protozoan parasites. A total of 76 faecal samples with representative intestinal parasite were then tested in the polyclonal and VP-1 assays. Of these, many gave an unacceptable number of significant optical densities in the polyclonal coproAg ELISA. In contrast, all were negative in the VP-1 ELISA, thus providing evidence for the species specificity of the VP-1 ELISA in faecal samples. These results with the VP-1 coproAg ELISA, although preliminary, justify further validation through the testing of more faecal samples from T. solium and T. saginata adult infected individuals.

Asymmetries of comparison

Tversky's (1977) seminal work on directionality injudgments of similarity demonstrated that people may not judge the similarity of A to B to be equal to the similarity of B to A. In a series of studies, we investigated comparison asymmetries. In Experiment 1, our aim was to extend Tversky's findings to a heterogeneous stimulus set, but no reliable asymmetries were observed. Experiment 2 employed a variety of comparison judgments, and, although some of these measures showed asymmetries, we still failed to observe asymmetries in rated similarity. A final attempt to obtain asymmetries used direction as a within-subjects factor, and for the first time, rating asymmetries were observed. Our data reinforce the idea of comparison asymmetries but suggest that similarity rating asymmetries are only observed under quite circumscribed conditions.

Detection of Leishmania braziliensis in naturally infected individual sandflies by the polymerase chain reaction

The natural infection of sandflies by Leishmania in wild-caught specimens was studied, using the polymerase chain reaction (PCR)-hybridization technique. The PCR was carried out using 2 oligonucleotides (primers 3J1 and 3J2) derived from a repetitive nuclear DNA sequence. The primers support the enzymatic amplification of a fragment of approximately 500 bp, present in the nuclear DNA of Leishmania braziliensis. The expected band was observed in 5 of 65 sandflies containing flagellates. After hybridization with a species-specific probe, we confirmed natural infection by L. braziliensis. The technique allowed the identification of Lutzomyia gomezi and Lu. panamensis as vectors of L. braziliensis in an endemic area of cutaneous leishmaniasis in Urama, Puerto Cabello district in Venezuela. As far as we are aware, this work constitutes the first report of natural infection of Lu. panamensis with L. braziliensis in the study area. We also demonstrate that PCR-hybridization is a suitable approach to establish the Leishmania-sandfly relationship and will be useful in epidemiological studies of leishmaniasis in endemic areas.

The genomic fingerprinting of the coding region of the beta-tubulin gene in Leishmania identification

We have demonstrated the polymorphism of the beta-tubulin gene region in Leishmania and its value in the identification of the parasite. In this work we have shown that the coding region of the gene has sufficient variation to accurately discriminate these parasites at the subgenus level. Nevertheless, intrasubgenus diversity, for particular restriction enzymes, was found in New World Leishmania belonging to the Leishmania subgenus. For instance, differences were found between mexicana and amazonensis strains. A unique pattern at the species level was found in particular species of both subgenera, e.g. L. (L.) major strain P and L. (L.) tropica belonging to the Leishmania subgenus, and L. (V.) panamensis strain LS94 from the Viannia subgenus. Particular endonucleases are diagnostic in Leishmania species discrimination as in the case of PvuII for the mexicana and amazonensis. This variation evidenced in the beta-tubulin gene region of Leishmania also occurred in other Kinetoplastida e.g. Trypanosoma cruzi, Leptomonas spp. and Crithidia spp. Moreover, these organisms showed a different genomic fingerprinting for the beta-tubulin gene among them and also Leishmania. Thus, the polymorphism of the coding region of the beta-tubulin gene can be used as a molecular marker for the identification of Leishmania.

Long-term outcome of Haemophilus influenzae meningitis in Navajo Indian children

OBJECTIVES

To determine the long-term neurologic, cognitive, and educational outcomes of Navajo children who survived Haemophilus influenzae type b meningitis.

DESIGN

Retrospective cohort study, with 3.6- to 15.0-year follow-up.

SETTING

Navajo Indian reservation.

PARTICIPANTS

Population-based cohort of 76 Navajo children with Haemophilus meningitis at less than 5 years of age between 1975 and 1986, with 41 (54%) consenting to undergo follow-up in 1990. Each case was matched to one nearest-age sibling and one unrelated age-matched control.

MAIN OUTCOME MEASURES

Standard intelligence test scores, neurologic abnormalities, and school performance.

RESULTS

The mean IQ for cases was lower than that for siblings (79 vs 87, P = .006) or age-matched controls (79 vs 95, P < .001). Twenty-nine percent of cases had severe neurologic sequelae, including mental retardation (24%), severe hearing loss (5%), cerebral palsy (7%), and seizure disorder (12%). Eight percent of siblings (relative risk for cases vs siblings, 8.0; P = .05) and 2% of age-matched controls (relative risk vs cases, 10.0; P = .01) had mental retardation. No siblings or age-matched controls had any other severe neurologic sequela. Twenty-nine percent of cases, 23% of siblings (relative risk, 2.5; P = .45), and 0% of age-matched controls (P = .001) required special education services, while 42% of cases, 23% of siblings (relative risk, 3.3; P = .10), and 11% of age-matched controls (relative risk, 4.0; P = .005) had been retained in a grade in school.

CONCLUSIONS

Navajo survivors of Haemophilus meningitis suffer more long-term neurologic, cognitive, and school-related disability than siblings or age-matched controls. They may also suffer higher morbidity than Haemophilus meningitis survivors in the general population.

Zoonotic cutaneous leishmaniasis due to Leishmania (Viannia) braziliensis associated with domestic animals in Venezuela and Brazil

After outbreaks of cutaneous leishmaniasis in Solano State, Venezuela, 5% of the population had parasitized ulcers while after similar outbreaks in Mesquita, Rio de Janeiro State, Brazil, 9% had the disease. In these foci children, including some under six years of age, were affected. There was no significant difference in the occurrence of the disease according to sex or type of employment. In Solano, 3% of dogs and 28% of donkeys had parasitized lesions, while in Mesquita these indices were 19.8% and 30.8% respectively. The parasite from man, dogs and equines was identified as Leishmania (Viannia) braziliensis, by zymodeme and serodeme characterization. In these foci there is evidence suggesting that leishmaniasis is a zoonosis, possibly with equines and dogs as reservoirs, although both a wild enzootic cycle and the role of man as a source of infection can not be ruled out. Transmission is assumed to occur peridomestically by sandfly vectors such as Lutzomyia panamensis in Venezuela and Lutzomyia intermedia in Brazil. Information about the origin of these foci suggests that infected equines may be an important factor in the dissemination of the parasite in a peridomestic situation where these sandflies are abundant.

Cutaneous leishmaniasis is frequent in equines from an endemic area in Rio de Janeiro, Brazil

In an endemic area of cutaneous leishmaniasis in Rio de Janeiro State where a mule had been found infected, a systematic search among equines was performed, resulting in the detection of Leishmania parasites in skin lesions of 30.8% of the animals, which included horses and mules. The eventual role of equines in the epidemiology of the human disease is being investigated.

[Cutaneous leishmaniasis in a mule (Equus caballus x Equus asinus) in an endemic area of the State of Rio de Janeiro]

É relatado o encontro de infecção por parasitos do gênero Leishmania, em lesão cutânea de uma mula (Equus caballus x Equus asinus) procedente de uma localidade endêmica de leishmaniose tegumentar, no Estado do Rio de Janeiro.

Study of an outbreak of cutaneous leishmaniasis in Venezuela. The role of domestic animals

During an outbreak of cutaneous leishmaniasis in a locality (Las Rosas, Cojedes State, Venezuela) previously non-endemic, 12.9% of humans, 7% of dogs and 21.4% of donkeys (Equus asinus) had lesions with parasites. The agent in the three hosts was identified as Leishmania braziliensis, subspecies braziliensis at least in man and donkey. The probable vector was Lutzomyia panamensis. No infection was found in a small sample of wild mammals examined. The outbreak was apparently linked with the importation of donkeys with ulcers, from endemic areas. The authors call attention to the fact that not only in the foci of "uta", but also in areas of the other forms of American cutaneous leishmaniasis, dogs are frequently found infected. They emphasize the necessity of searching for the infection in donkeys and of performing hemocultures and xenodiagnosis with sandflies in human, canine and equine cases, to verify their possible role as sources of infection, and not merely as dead ends in the epidemiological chain of the disease.