Control of the transmission of Chagas' disease in Mambai, Goias, Brazil (1980-1988).

The results of entomologic surveillance conducted after Chagas' disease control in Mambai, Goias, Brazil are reported for the years 1985-1988, including a summary of results from 1980 to 1988. A progressive decrease in the incidence of Triatoma infestans in houses reached zero in 1988. The threat of secondary vector colonization and the continued need for vigilance are discussed.

Improvements in routine xenodiagnosis with first instar Dipetalogaster maximus (Uhler 1894) (Triatominae).

First instar Dipetalogaster maximus proved as effective as third instar Triatoma infestans in detecting circulating Trypanosoma cruzi in patients with chronic infections examined in a routine xenodiagnostic laboratory. Since rearing costs are diminished, D. maximus has now replaced T. infestans as the xenodiagnostic agent in our laboratory. However, further work is needed to define the optimal conditions necessary when using this species in xenodiagnosis.

High continuous antimony therapy in two patients with unresponsive mucosal leishmaniasis.

The treatment of two patients with severe mucosal leishmaniasis due to Leishmania braziliensis braziliensis is described. Both patients had received much prior antimonial therapy and one had relapsed after a total dose of 2.5 g of Amphotericin B. Both patients responded to prolonged continuous Pentostam therapy at a daily dose of 20 mg Sbv/kg/day for 62 days in one case and for 85 days in the other. Pentavalent antimonials can be curative in such protracted courses in selected patients unresponsive to standard chemotherapy.

Clinical observations of unresponsive mucosal leishmaniasis.

We report the long-term clinical follow-up of two patients with unresponsive mucosal leishmaniasis due to Leishmania (Viannia) braziliensis from the Três Braços area in Bahia State, Brazil. Both were agricultural male workers with extensive upper respiratory mucosal involvement that was not cured with conventional and experimental therapy.

Mucosal leishmaniasis ("espundia" Escomel, 1911).

One of the more serious clinical forms of leishmaniasis occurs in espundia when the mucosae of the upper respiratory passages are inflamed. This complication is a metastasis from a skin lesion caused by Leishmania braziliensis braziliensis (Lbb) although cases have been described associated with other leishmanial species. Epidemiological data suggest that a detectable mucosal metastasis occurs in fewer than 5% of patients infected with Lbb in our study area. The determinants of this complication are still largely obscure. The granuloma usually commences on the nasal septum. In about two-thirds of our patients the lesion remained restricted to the nose. In the rest the pharynx, palate, larynx and lips were involved, in this order. It is often difficult to isolate the parasite and for routine diagnosis the leishmanin skin reaction and serological tests are helpful. Although a serious condition, with possible mutilation and even death as subsequent complications, treatment is still mainly with pentavalent antimonials, introduced 40 years ago. These are most unsatisfactory for field use, being given parenterally and relatively toxic. In mucosal leishmaniasis, if sufficient antimony can be administered in a regular daily dose, the relapse rate is small (3 of 42 patients followed for a mean of 5 years). Also, antimony treatment of the initial skin ulcer due to Lbb followed for a mean of 4 years of 83 patients resulted in subsequent mucosal metastasis in only 2. Since espundia is relatively rare, specific treatment targeted to this specific problem is the efficient short term solution. At present there is no satisfactory alternative drug to those in current use.

A histological classification of mucocutaneous leishmaniasis in Brazil and its clinical evaluation.

Biopsies of skin and mucosal lesions were made on 60 well documented Brazilian patients with untreated cutaneous or mucocutaneous leishmaniasis, whose response to treatment was subsequently evaluated in 38 cases. The biopsies were examined with a view to classification after correlation with clinical and immunological findings. Although there was no simple or unified spectrum, five histological groups were defined and found to have some clinico-prognostic significance. In two groups the cases were all cutaneous with a relatively good prognosis. In another two groups they were evolving as mucocutaneous with a poor prognosis. The fifth group showed mixed characteristics with a tendency to relapse. There was no strong correlation with serum antibodies or Montenegro skin test, which were usually positive, or with parasite load, which was always low. The tissue response was distinguished from that in oriental sore by the degree of connective tissue involvement in all groups. It was the primary response in two groups, and subsidiary to a mono-nuclear response in the others. It suggested damage due to extra-cellular parasites or immune complexes. It did not correlate with the distinction between cutaneous and mucocutaneous disease. The single, most favourable, prognostic feature in either the cellular or connective tissue component was necrosis with a reactive response.

Nifurtimox in the treatment of South American leishmaniasis.

A trial of Nifurtimox (Lampit) in 26 patients with mucocutaneous leishmaniasis is reported. 13 patients with cutaneous lesions and 13 patients with mucosal disease were treated with a daily oral divided dose of 10 mg/kg body-weight for 30 days. 46% of the cutaneous cases and only 15% of the mucosal cases apparently responded to this regimen during at least one year of follow up. The difficulties of assessing cure in this disease are briefly discussed. We consider that Nifurtimox remains an investigational drug. While possibly exhibiting some anti-leishmanial activity it cannot be recommended for routine use in either form of the disease.

Further trials of nifurtimox in mucocutaneous leishmaniasis.

At a dosage level of 8 to 10 mg/kg body-weight daily for 120 days nifurtimox was associated with clinical healing of cutaneous leishmaniasis in five of eight patients. At a dosage level of 20 mg/kg body-weight daily for 10 days in six of 10 patients the skin ulcer healed. Results and the reasons why both schemes are impracticable are briefly discussed.

A comparison of Rhodnius prolixus, Triatoma infestans and Panstrongylus megistus in the xenodiagnosis of a chronic Trypanosoma (schizotrypanum) cruzi infection in a rhesus monkey (Macaca mullatta).

Fifth instar Rhodnius prolixus, Triatoma infestans and Panstrongylus megistus were fed on a rhesus monkey (Macaca mullatta) with a chronic infection of Peru strain Trypanosoma cruzi and examined 30 days later for the presence of trypanosomes in the rectum. No correlation could be demonstrated between either blood meal size or sex and the subsequent development of a rectal infection with T. cruzi. As T. infestans and P. megistus were more highly infected than R. prolixus in terms of both percentage infected and degree of infection, the two former species can be regarded as more suitable for the xenodiagnosis of this particular strain of T. cruzi in M. Mullatta.

Attempts to produce megasyndrome in mice using stocks of Trypanosoma cruzi associated with megaoesophagus in man.

Two stocks of Trypanosoma cruzi isolated from patients with advanced megaoesophagus produced megastomach in chronically infected mice. The mice showed evidence of stomach dilatation and a delay in intestinal transit time. These findings are discussed in the light of the hypothesis that regional variations in T. cruzi determines mega formation in man.

Skin reactions to bug bites as a result of xenodiagnosis.

Cutaneous allergic reactions to bites of two bug species Triatoma infestans and Dipetalogaster maxima, were studied in an area where T. infestans is the local domestic vector. While more delayed skin reactions occurred with the indigenous vector, reactions also occurred with D. maxima. Repeated exposure to D. maxima produced more intense immediate skin reactions. First-stage D. maxima bugs produced a lower frequency and intensity of skin reaction. It is concluded that further work on this problem is necessary as it prejudices the use of xenodiagnosis in field surveys.

Dipetalogaster maximus (Hemiptera, Triatominae) for xenodiagnosis of patients with serologically detectable Trypanosoma cruzi infection.

In patients serologically positive for Trypanosoma cruzi infection the three bug species/instar combinations used in xenodiagnosis showed third-instar Dipetalogaster maximus to be more efficient in detecting circulating trypanosomes than the first instar of the same species which, in turn, is more sensitive than third-instar Triatoma infestans. The sensitivity of the pool technique of faecal examination compared with individual dissection was investigated. Four pool examinations (the product of 20 bugs) were equivalent to 10 individual bug dissections. Because of the ease of providing large numbers of bugs for mass xenodiagnosis, first-instar D. maximus has replaced third-instar T. infestans in our routine work. The value of third-instar D. maximus as a xenodiagnostic agent needs further investigation.

Experimental Trypanosoma cruzi infection in rhesus monkeys 111. Electrocardiographic and histopathological findings.

In five rhesus monkeys surviving 'Peru strain' or 'strain 7' Trypanosoma cruzi infection for six to eight years, positive xenodiagnosis results and high indirect fluorescent antibody titres (4096 - 65536) persisted until the animals were killed. Abnormal electrocardiograph patterns in two monkeys (H and K) were possibly compatible with myocardial damage. Histopathological changes attributable to T. cruzi infection were minor in four monkeys but severe in one (R). In this animal, infected with what was judged previously to be the less virulent of the two T. cruzi stocks used ('strain 7'), there was severe myocarditis, with myofibre degeneration, and lesions of the oesophagus. Elevated serum levels of five enzymes were not detected in any of the chronically infected monkeys.

A focus of mucocutaneous leishmaniasis in Três Braços, Bahia, Brazil: characterization and identification of Leishmania stocks isolated from man and dogs.

The characterization and identification to species and subspecies of 20 stocks of Leishmania isolated from the region of Três Braços, Bahia, Brazil, are described: 17 stocks were from patients and three from dogs. The following techniques were used (i) biological (growth in culture, hamster tissues and phlebotomine gut), (ii) biochemical (isoenzyme and kinetoplast DNA analysis) and (iii) immunological (using monoclonal antibodies). All except two stocks belong to the L. braziliensis complex. One of these two corresponded to L. mexicana amazonensis but the other, while clearly in the mexicana complex, showed slight differences from the L. mexicana amazonensis reference strain on isoenzyme analysis. Two stocks from different lesions in the same patient and with different growth characteristics in hamster tissues were both identified as L. braziliensis braziliensis. All the fully characterized stocks of the L. braziliensis complex were identified as L. braziliensis braziliensis. L. braziliensis guyanensis was not identified. Dog and human stocks of L. braziliensis braziliensis were indistinguishable. From these findings and other evidence, L. braziliensis braziliensis seems to be the predominant species transmitted in Três Braços.

Experimental Trypanosoma cruzi infections in rhesus monkeys. II. The early chronic phase.

Information on the acute and early chronic phases of infection with Trypanosoma cruzi in eight rhesus monkeys is reported with particular reference to the pattern of subpatent parasitaemia and serology. Xenodiagnosis was superior to animal inoculation and blood culture in its capacity to detect subpatent parasitaemia. Each monkey showed an individual, relatively constant pattern of this not related to the nature of the inoculum. Levels of indirect fluorescent and indirect haemagglutinating antibodies remained elevated during a year of observations. One monkey died with a megaoesophagus. Another monkey after challenge with a heterologous strain by orbital inoculation failed to develop Romana's sign and showed no change in serum antibody levels or degree of xenopositivity.

Long-term follow-up of patients with Leishmania (Viannia) braziliensis infection and treated with Glucantime.

Seventy-nine patients with cutaneous (62) or mucosal (17) infection with Leishmania (Viannia) braziliensis in Três Braços, Bahia, Brazil, were followed for at least 4 years after initiating treatment with antimony. Cutaneous relapses occurred in 6/62 (10%), mucosal relapse after cutaneous infection in 2/62 (3%), and mucosal relapse after mucosal disease in 2/17 (17%). It is concluded that relapse (cutaneous and mucosal) is rare after adequate antimony therapy and that no definite prediction of relapse (clinical, serological or by skin reaction) is possible.

A new prognostic index in surgery and parenteral feeding: the ratio of triiodothyronine to reverse triiodothyronine in serum (T3/rT3 ratio).

Serum concentrations of albumin, triiodothyronine (T3), and reverse triiodothyronine (rT3) were measured in 46 patients on the first day after routine gastrointestinal surgery, and the molar ratio T3/rT3 was calculated. The median value of this ratio, but not of albumin, was significantly lower in 11 who subsequently suffered major septic complications than in the remainder. Measurement of the ratio correctly predicted the outcome of 80% of individuals. The T3/rT3 ratio, midarm muscle circumference (MAMC), triceps skin fold (TSF) and serum concentrations of albumin and transferrin were measured in 23 patients at referral for parenteral feeding. Median values of T3/rT3 ratio, MAMC and transferrin, but not of the other parameters, were significantly lower in nine who died than in survivors. Measurements of the ratio, MAMC and transferrin correctly predicted the outcome of 87%, 78% and 74% of individuals, respectively.

Mucosal leishmaniasis in Brazil.

The clinical diagnosis and laboratory identification of Leishmania braziliensis braziliensis, a parasitic disease affecting the upper aerodigestive tract, is difficult. A retrospective computer-assisted analysis of patient records was done after examination of 58 patients with mucosal leishmaniasis in an endemic area of L. braziliensis braziliensis in Bahia, Brazil during January 1987. Biopsies of clinically active and clinically inactive mucosal patients were examined for parasites using routine hematoxylin and eosin histopathology and a new technique for rapid detection of Leishmania amastigotes using a genus-specific indirect immunofluorescent assay. No amastigotes were found in specimens from seven patients with clinically inactive mucosal disease using immunofluorescent monoclonal assay techniques, whereas specimens from seven out of 14 patients with clinically active mucosal disease were positive. These results suggest that the immunofluorescent antibody technique is markedly superior in identifying the intracellular amastigote in tissue sections of mucosal biopsies when compared to histopathology techniques or with other standard tests done in rural areas of Brazil. Various clinical and laboratory test data of the entire group of patients were examined and the efficacy of treatment evaluated. The median interval of time noted between cutaneous and mucosal disease was 4.5 years. Relapse was noted in 31% of patients treated with a low dose of meglumine antimoniate (10 mg per kg of body weight). Patients treated with a high dose of meglumine antimoniate (20 mg per kg of body weight) had a relapse rate of 27.3%. A chi-square statistical analysis revealed no significant difference (chi 2 = 0.049) between the two groups. Patients were considered cured if mucosal granulations were clinically absent after 4.6 years.

Pentavalent antimonial inhibition of the osmotic effect of oxytocin on the isolated toad bladder.

The inhibition of osmotic stimulated water flow in the isolated toad bladder by 0.1 mM sodium stibogluconate (pentavalent antimony) is described. Pentavalent antimony on the serosal surface significantly inhibited oxytocin-induced water flow but when the drug was added to the mucosal surface only the effect of low oxytocin concentrations was reduced. The phosphodiesterase inhibitor pentoxifylline, when present on the serosal side, blocks the effect of pentavalent antimony on stimulated water flow. No effect was detected when indomethacin was present on the serosal side. It is suggested that phosphodiesterase activation might play a role in the mechanism of pentavalent antimonial inhibition of oxytocin-induced water flow in the isolated toad bladder. The effect obtained when sodium stibogluconate on the serosal side was replaced with antimony pentachloride (SbCl5) supports the view that the metal in the molecule is responsible for the inhibition of the effect of oxytocin.

Recovery of Leishmania (Viannia) braziliensis from inoculated hamsters.

Leishmania (Viannia) braziliensis has never been isolated from wild animals although it is apparently capable of inducing infections in man, dogs, and donkeys. An analysis of the standard hamster culture system for analyzing infectivity of Leishmania sp. was undertaken. Results indicate that for L. (V.) braziliensis, routine cultivation of aspirates taken from the inoculation sites of 1-mo-infected hamsters should be undertaken. Moreover, in at least 1 of the 3 strains examined, isolation of the parasite was only achieved after 84 days of cultivation.