Biomedical subjects
Publications and source records attributed to P P Chieffi.
In the present review, we will discuss the Schistosoma mansoni form, which is the most widely distributed schistosome in humans and is found both in the Old and New Worlds. The main features of the natural history of mansonic schistosomiasis are reviewed, with emphasis on the clinical forms of the disease, their diagnosis and treatment.
The present survey from the State of Alagoas (Brazil) emphasized, once again, the importance of peridomestic or neighbourhood foci in the transmission of schistosomiasis mansoni. Although the study area consisted of a compact and densely populated urban community (Bairro Frio, União dos Palmares county), prevalence as well as the distribution of high egg counts was quite patchy, exhibiting a spatial pattern correlated with the distribution of ditches and other small-sized collections of surface water. Despite the availability of satisfactory water supply in most households, as well as the absence of any major body of water capable of furthering transmission, egg counts in Bairro Frio exceeded any other in our previous experience. Morbidity, however, appeared to be insignificant, a trend which has been observed over the last decade in several other highly endemic areas. It appears clear to the authors that the control of transmission requires investment in environmental intervention and that this proposal, far from being utopic, can be furthered by quite modest means and through the participation of community or neighbourhood groups.
The biological literature contains many examples of mutual influences between different species of parasites, especially with respect to concomitant helminth infections. Several situations are known in which the association of infection by Schistosoma mansoni with other pathogens in the same host results in a type of disease which differs from the simple summation of the individual effects of each infection. The present study concerns concomitant infections involving S. mansoni and enterobacteriaceae; S. mansoni and other helminths such as Ascaris lumbricoides, Ancylostomids, Toxocara canis and species of the genus Hymenolepis; S. mansoni and different protozoa such as Trypanosoma cruzi, T. brucei, Toxoplasma gondii and Plasmodium berghei. The interaction between hepatitis B virus and S. mansoni, leading to prolonged viremia and worsening of liver damage, is also discussed. The paper also treats the simultaneous occurrence of schistosomiasis and other aggravating factors such as malnutrition and neoplasias which may alter the host's response to the trematode.
In 1988, nine cases of human parasitism by Phagicola sp. were diagnosed in the municipality of Registro (São Paulo State, Brazil) by stool examinations, in patients who ate raw mullet (Mugil sp.). Six (66%) of the nine patients suffered from flatulence and four (44%) had diarrhoeal episodes; six (66%) showed slight eosinophilia. On the same occasion, 61 dogs and 11 cats from Registro were also submitted to stool examination. Only one dog (1.6%) showed Phagicola eggs in the stool. All patients were treated with a single dose of praziquantel (50 mg kg-1 body weight) and control stool tests performed on the 15th, 30th and 60th days post-treatment showed no trematode eggs.
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Inocula of S. mansoni and T. gondii well tolerated by albino mice when given singly, were given concomitantly to groups of animals. Few notable effects were observed when toxoplasmosis preceded schistosomiasis, but the S. mansoni leads to T. gondii model, with an interval of 59 days between infections, led to massive mortality, great weight loss and a striking splenomegaly. These findings are very similar to data from previous work on the S. mansoni leads to Trypanosoma cruzi model. The authors believe that other examples of such a type of potentialization should be searched for in human schistosomiasis also.
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Severe morbidity due to schistosomiasis mansoni is now quite rare in Brazil; thus it is proposed that surveillance plus selective and multidisciplinary intervention limited to areas at high risk be the next step. Such a policy has to be carried out periodically and on a state-wide scale, and therefore will have to rely upon cheap and time-saving sampling procedures. Clinical features cannot at present be used as indicators, with the exception of grossly enlarged livers, which are more frequent in areas at high risk. Overall prevalence rates for a county or even city may also be misleading, even if broken down into units of smaller size. Thus, egg counts in the young age groups remain the best indicators for the detection of areas at high risk (i.e., the main foci of transmission). Egg counts performed on pooled specimens adequately reflect the risk rating of a particular neighbourhood, and have a favourable cost-benefit ratio. In addition, it is suggested that field personnel be trained in the empirical recognition of potential foci; such 'screening by suspicion' has been tested and found to be reliable.
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Fifteen adult patients with assymptomatic infection due to Clonorchis sinensis, diagnosed by coprological examination, were studied. They all came from Asia (twelve from Taiwan, two from South Korea and one from Hong Kong) and were examined at the Adolfo Lutz Institute and the Department of Infectious Diseases, School of Medicine, University of São Paulo, in São Paulo, Brazil. Six patients were women and nine men. All studied patients were admitted to hospital and treated with praziquantel (60 mg/kg). Previous to treatment and on the 15th, 30th and 60th days after praziquantel administration, patients were submitted to quantitative stool examinations, according to Kato-Katz's technique and to hematological and biochemical serum analysis. After a 60 day follow-up nine patients (60%) were negative for C. sinensis eggs in stools. Those not cured after praziquantel administration (six patients, 40%) revealed a sharp decline in faecal elimination of C. sinensis eggs.
An enzyme-linked immunosorbent assay (ELISA), employing antigens from Toxocara canis larvae and the absortion of suspected sera with Ascaris lumbricoides extracts was used in a seroepidemiological study performed in five municipalities of São Paulo State, Brazil (São Paulo, Campinas, Santos, Marília and Presidente Prudente) in order to determine the frequency of antibodies to Toxocara. In 2,025 blood samples collected, 806 proceeded from male subjects and 1,219 from females; 483 samples were collected from subjects under 15 years of age and the remaining 1,542 from subjects aged 15 years or over. Among the 2,025 sera investigated, 3.60% had antibodies to Toxocara at significant levels. A moderate predominance of infection with Toxocara among male subjects (3.72%) was observed, although the difference was not statistically significant when this rate was compared with that for female (3.28%). Related to age, a higher frequency of positive results was detected among subjects under 15 years (6.41%) against the older group (2.53%). A trend of more elevated rates of infection was observed in municipalities with high demographic densities (São Paulo, Campinas and Santos). Nevertheless, such findings only appeared to be statistically significant in subjects younger than 15 years.
A comparative study among different serovars of Leptospira interrogans was performed in order to prepare antigens to detect IgM antibodies by ELISA in early and late phase of human leptospirosis. Ten serovars were chosen among the most prevalent detected by microscopic seroagglutination (SAM) in São Paulo city. Using ELISA-IgM five of them showed better results (canicola, hebdomadis, icterohaemorrhagiae, cynopteri and brasiliensis). These ones were also studied in a pool. The non-treated antigens showed higher reactivity than the Triton X-100 (4%/50 degrees C/4h). ELISA-IgM using individually or pool of non-treated antigens proved to be reliable with high sensitivity and should be used for an earlier diagnosis of leptospirosis, as a trial test. Faster diagnostic elucidation can be useful to detect epidemic situations, so, allowing epidemiological surveillance interventions.
We report one case of parasitism by Phagicola sp. (Trematoda, Heterophyidae) in a 31 year-old woman who, in 1987, travelled and stayed several months in the municipality of Cananéia (SP), where she ingested, in various occasions, raw mullet (Mugil sp.). The patient referred mild intestinal pain and laboratory examinations showed eggs of Phagicola sp. in the stools and a slight increase in eosinophil blood levels (8%). After treatment with praziquantel (75 mg/kg per day for three days) all the symptoms and signs disappeared. This is, certainly, the first record of human infection by Phagicola sp. in Brazil and, perhaps, in countries other than the U.S.A. where unclear references to a few human cases were reported in the South-eastern region.