Masato Kawabata

A preliminary note on the intestinal parasites of wild chimpanzees in the Mahale Mountains, Tanzania

Feces of wild chimpanzees in the Mahale Mountains, Tanzania, were inspected for intestinal parasites under a compound microscope. Eggs or larvae ofOesophagostomum, Strongyloides, Trichuris, Prosthenorchis, andBertiella were found. Intestinal nematodes significantly increased in the mid-rainy season. This finding supports (or, at least, is not in conflict with) the hypothesis thatAspilia leaves which are occasionally swallowed by chimpanzees may function as a vermicide, since ingestion of such leaves also increases significantly in the mid-rainy season.

Phlebotomine sandfly species in Paraguay and their infection with Leishmania.

Nine species of sandflies, Lutzomyia (Nyssomyia) whitmani (Antunes and Countinho), Lutzomyia (Nyssomyia) intermedia (Lutz and Neiva), Lutzomyia (Psathyromyia) shannoni (Dyar), Lutzomyia migonei (Franca), Lutzomyia (Pintomyia) fischeri (Pinto), Lutzomyia (Pintomyia) pessoai (Countinho and Barretto), Lutzomyia cortelezzii (Brethes), Lutzomyia walkeri (Newstead) and Lutzomyia (Trichopygomyia) longispinus (Mangabeira), were caught, by human bait and Shannon trap, in four areas of Paraguay hyper-endemic for human leishmaniasis. Lutzomyia whitmani and L. intermedia were the predominant species. All the species collected were found to be anthropophilic. Hindgut infections with leishmanial promastigotes were observed in only one (0.38%) of the 266 L. whitmani dissected. No L. intermedia were found infected, giving an overall infection rate of one (0.16%) of 615 flies dissected. The results indicate a very low rate of natural infection in endemic areas of Paraguay.

IgM rheumatoid factors in Guatemalan onchocerciasis

The possible presence of IgM Rheumatoid factors (RF) and anti-DNA antibodies was investigated in sera of patients with Guatemalan onchocerciasis. The mean value of IgM RF in the patients was found to be significantly higher than that in controls and 10 out of 57 patients had increased levels of IgM RF. In addition, serum IgM levels in those 10 patients with increased levels of IgM RF were significantly elevated. In contrast, no significant increase of serum anti-single-stranded (ssDNA) and double-stranded DNA (dsDNA) antibodies were found in the patients.

Association of electrocardiographic abnormalities with seropositivity to Trypanosoma cruzi in Ecuador

In highland Ecuador (province of El Oro), electrocardiograms (ECGs) were taken and analysed from 340 subjects, of whom 154 were seropositive to Trypanosoma cruzi by indirect haemagglutination test. Abnormal ECGs were present in 40.3% of seropositive individuals and 8.1% of seronegatives, and were slightly more common in seropositive males than in seropositive females. In seropositive individuals, the prevalence of abnormal ECG progressively increased with age and reached its peak level of 64.0% in the age group over 60 years, implying that Chagas disease in Ecuador produces little mortality among seropositive individuals. The most common ECG alterations were ventricular conduction defects: 26 of 117 seropositive individuals in the age group over 40 years had complete right bundle branch block. The frequency of atrioventricular block and arrhythmias was also associated with seropositivity to T. cruzi. A further ECG examination in lowland (province of Guayas) showed that the prevalence of abnormal ECGs there was significantly lower than that in highlands. These results suggest possible differences between T. cruzi strains in the two geographical areas of Ecuador.

Biting activity of two anthropophilic species of sandflies, Lutzomyia, in an endemic area of leishmaniasis in Ecuador.

The biting patterns of Lutzomyia trapidoi and Lu. hartmanni, vectors of leishmaniasis, were studied using a human bait in an endemic area on the Pacific slope of the Andes in Ecuador. The results suggest that Lu. trapidoi is primarily an early biter at dusk, with the first peak at 20.00-21.00 hours and the second at 03.00-04.00 hours; and that Lu. hartmanni bites more constantly throughout the night, with a pronounced peak between 23.00 and 24.00 hours. The biting activity, however, shows a marked variation at each site and between different collections at the same site. The activity and the biting places on man are discussed in relation to human infection with leishmaniasis in the area and the location of lesions on patients.

Circulating Immune Complexes and Their Possible Relevance to Other Immunological Parameters in Guatemalan Onchocerciasis

Circulating immune complexes (CIC) were demonstrated in sera of Guatemalan patients with onchocerciasis by Raji cell radioimmunoassay. 44% of patients but none of controls had abnormally high concentrations of CIC in their sera. The increased concentrations of CIC were found more frequently in patients with lower density of microfilariae in their skin biopsies. Patients with higher concentrations of CIC appeared to have increased titers of serum antibodies to Onchocerca volvulus. A depression of both humoral immune response to tetanus toxoid and delayed hypersensitivity reaction to PPD were found in patients with onchocerciasis. CIC may be involved in modulation of the immune response in onchocerciasis.

The relationship between severity of ulcerated lesions and immune responses in the early stage of cutaneous leishmaniasis in Ecuador

The relationship was examined between the severity of ulcerated lesions and immune responses in 19 Ecuadorian patients in the early stages of New World cutaneous leishmaniasis. As an immunological assay, the humoral immune response was assessed by enzyme-linked immunosorbent assay (ELISA) and the cell-mediated response by delayed type skin test for leishmanial antigen (leishmanin test). There was a statistically significant correlation (r = 0.61, P less than 0.01) between the total area of ulcerated lesions and the reciprocal titre of ELISA in identical subjects. However, no significant difference was observed in the ELISA titre between patients with a single lesion and those with multiple lesions (chi 2 = 7.06, df = 5, P greater than 0.2). A correlation (r = 0.48, P less than 0.05) was observed between the area of lesions and the intensity of leishmanin test; further, the ELISA titre also correlated to the intensity of leishmanin test in the identical subjects (r = 0.71, P less than 0.01). These results suggest that the severity of ulcerated lesions relates to the activation of both the humoral and cell-mediated immune systems in the early stage of New World cutaneous leishmaniasis.

Seasonal variation in the microfilarial skin density of Onchocerca volvulus and in the biting activity of Simulium spp. in Guatemala

The density of Onchocerca volvulus microfilariae in the skin of 11 carriers was examined by carrying out a monthly examination in a single endemic area of Guatemalan onchocerciasis. The results obtained suggested the possibility of a seasonal variation in the microfilarial skin density. Almost all of the volunteers participating had shown a peak concentration of microfilariae in September, followed by August or October. The highest biting densities of Simulium ochraceum, the principal vector of onchocerciasis in Guatemala, occurred from September to the following January. It thus appears that the seasonal variation in the microfilarial density may correspond, to some extent, with the biting activity of the vector, S. ochraceum and/or with climatic changes in the area.

Cutaneous leishmaniasis in south-eastern Paraguay a study of an endemic area at Limoy

An epidemiological study was performed on leishmaniasis in a newly established community in south-eastern Paraguay. 149 persons, of 172 inhabitants, were thoroughly examined by clinical, parasitological and immunological (leishmanin skin test) examinations. 88 of those examined (59%) were clinically positive for dermal and nasal (mucosal) lesions or dermal scars, while 74 (50%) were positive by the leishmanin test. Of the 88 persons, 66 (75%) were positive for both leishmanial (dermal and nasal) signs and skin test; these subjects were therefore considered to be leishmaniasis patients. Most of the patients (60%) had a single dermal lesion. Among the 66 leishmaniasis patients, serious mucosal (nasal septum) lesions were observed in the 41 subjects: 2 had destruction of the septum, 8 had ulceration and 31 had erythema. In this community the persons with dermal and/or nasal problems had been treated with meglumine antimonate (Glucantime), without any precise diagnosis having been made by parasitological or immunological examination. The socio-economical and socio-medical points of view aspects are discussed.

The distribution of microfilariae in the skin of Guatemalan onchocerciasis patients: an evaluation of diagnostic potentials

Quantitative examinations for the distribution and density of microfilariae were carried out on male Guatemalan onchocerciasis patients by taking 6 or 13 skin biopsies each from 74 subjects. We found that microfilariae were distributed most frequently on the iliac crest and secondarily in the scapular region; higher detection rates and greater microfilarial densities were seen in these areas. From these results we recommend the taking of biopsies from both of these anatomical regions so as to avoid false negative cases. The infected patients were classified into 3 groups (light, moderate and heavy infections) on the basis of the numbers of negative skin snips out of the 13 biopsies taken. In heavy infections, a higher densities of microfilariae were detected in the head and neck regions, as compared with the densities in the lower extremities (calf). The high concentration of microfilariae in these regions is of importance in relation to the development of eye lesions and/or transmission. Of patients who had microfilariae in the anterior segment of the eye some had negative skin biopsies frm the outer canthus, retroauricular region and neck.