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Biomedical subjects

K E Mott

Publications and source records attributed to K E Mott.

At least 19 recordsLinked to original sources

Liver ultrasound findings in a low prevalence area of S. japonicum in China: comparison with history, physical examination, parasitological and serological results.

The paper describes a study carried out in a community in Dongdian township, Anhui Province, People's Republic of China. Medical history and the results of a physical examination, ultrasound investigation, parasitological and serological tests for Schistosoma japonicum infection were compared in 661 persons of 169 households. A lack of correlation between parasitological and serological indicators of infection and morbidity was observed in this area of low (6.4%) prevalence and intensity of infection. The prevalence of abnormal ultrasound findings in the liver in this population was high (56%), and was significantly higher than the prevalence of S. japonicum infection. The abnormal ultrasound findings correlated with a history of schistosomiasis, and the correlation increased significantly according to the number of times treated and the time since the last treatment, which suggested that past parenteral treatment has a role in the high rate of abnormal liver ultrasound findings. The significant correlation between the qualitative and quantitative serological results and abnormal ultrasound parenchymal patterns suggests that cross-reactivity between the etiology of the parenchymal disease and these tests is occurring. The presence of HBsAg correlated with the composite presence of ultrasound abnormalities of the liver parenchyma: increased echogenicity, periportal fibrosis and/or nodules and irregular fibrosis, whereas a normal ultrasound pattern was associated with the absence of HBV antigenemia.

Adolescent

Selective population chemotherapy among schoolchildren in Beheira governorate: the UNICEF/Arab Republic of Egypt/WHO Schistosomiasis Control Project.

Selective population chemotherapy using a single dose of praziquantel (40 mg per kg body weight), which was offered to 29,365 schoolchildren in Abu El Matameer and 40,241 in Abo Homos districts, Beheira governorate in the Nile delta, reduced the prevalence of schistosomiasis from 75.4% to 40.9% (reduction of 45.8%) and from 80.5% to 30.8% (reduction of 61.7%), respectively. Of those with only S. mansoni infection, 10.6% before treatment and 1.7% one year later had more than 800 eggs per gram of faeces. The prevalence of S. haematobium in Abu El Matameer was reduced from 35.4% to 7.4% after a single treatment. Infections with both S. mansoni and S. haematobium were reduced by more than 90% after one year. These reductions in prevalence and intensity of schistosomiasis in the face of continuing transmission and water contact augur well for the future role of chemotherapy in control programmes.

Adult

ZOOM: a generic personal computer-based teaching program for public health and its application in schistosomiasis control.

Schistosomiasis, a group of parasitic diseases caused by Schistosoma parasites, is associated with water resources development and affects more than 200 million people in 76 countries. Depending on the species of parasite involved, disease of the liver, spleen, gastrointestinal or urinary tract, or kidneys may result. A computer-assisted teaching package has been developed by WHO for use in the training of public health workers involved in schistosomiasis control. The package consists of the software, ZOOM, and a schistosomiasis information file, Dr Schisto, and uses hypermedia technology to link pictures and text. ZOOM runs on the IBM-PC and IBM-compatible computers, is user-friendly, requires a minimal hardware configuration, and can interact with the user in English, French, Spanish or Portuguese. The information files for ZOOM can be created or modified by the instructor using a word processor, and thus can be designed to suit the need of students. No programming knowledge is required to create the stacks.

Computer-Assisted Instruction

Global schistosomiasis database: practical considerations in the design of a user-friendly database.

A computerized database for monitoring global schistosomiasis data is discussed. The potential target users include schistosomiasis program managers, Ministries of Health of endemic countries, consultants, and WHO Regional Offices. The concept behind the design of the database structure, the user interface and the query interface is addressed along with a brief description of the hardware and software used. The database, holding information on 76 schistosomiasis endemic countries around the world, has been tested in the WHO Regional Offices with positive results.

Databases, Factual

An outbreak of acute Chagas's disease in the São Francisco Valley region of Bahia, Brazil: triatomine vectors and animal reservoirs of Trypanosoma cruzi.

Following reports of an unusually high incidence of acute Chagas's disease and the appearance of large numbers of Triatoma infestans in the southwestern region of the State of Bahia, triatomine bugs (Hemiptera: Reduviidae) and domestic animals in one of the affected communities were surveyed and examined for infection with Trypanosoma cruzi. Triatoma infestans was prevalent in houses and was also found in peridomestic habitats. T. sordida and T. pseudomaculata occupied peridomestic and sylvatic habitats and T. brasiliensis was found only among rocks far from houses. Panstrongylus megistus, formerly present in the region, was not found. Trypanosoma cruzi was detected in 19.5% of Triatoma infestans, 11.5% of T. sordida, 19% of dogs, 29% of cats and 100% of rats examined. A disproportionate number of early instar bugs were infected with Trypanosoma cruzi, suggesting that a rapid increase in the rate of transmission had recently occurred. The history of the domestic triatomine fauna of the region since 1912 is reviewed, and it is proposed that the relatively recent arrival of Triatoma infestans initiated a domestic cycle linked to peridomestic and sylvatic cycles of Trypanosoma cruzi transmission. Increased human mobility, the use of DDT for malaria control, and drought conditions are considered as factors which might have contributed to the outbreak of human infection.

Animals

Prevalence of parasitemia and seroreactivity to Trypanosoma cruzi in a rural population of Northeast Brazil.

Age-specific prevalence rates of parasitemia and seroreactivity to Trypanosoma cruzi were determined in a rural area endemic for Chagas' disease in Northeast Brazil. Parasitemia was detected by blood cultures and xenodiagnosis, and serum antibodies to the parasite were measured by the complement fixation (CF) and indirect immunofluorescence (IFA) tests. Of the 116 persons examined, 39 (33.7%) had antibodies and 23 (19.8%) had parasitemia. Ninety-six percent of parasitemic individuals were seropositive and 56% of seropositive individuals were parasitemic. The percentage of seropositive individuals with detectable parasitemia declined with age; all seropositive children in the 1- to 4-year age group and two-thirds of seropositive persons 5-19 years old had parasitemia while only one-third of seropositive adults above 19 years had parasitemia. CF and IFA tests were equally sensitive in detecting persons with parasitemia. Xenodiagnosis was more sensitive than culture for detecting parasitemia, but the two methods together were more sensitive than either method alone. Using the age-dependent relationship of parasitemia to seropositivity determined in this study, the prevalence rate of T. cruzi parasitemia was estimated in a much larger adjacent population in which seropositivity rates and the demographic structure were already known.

Adolescent

Stability of faecal egg excretion in Schistosoma mansoni infection.

Stability of Schistosoma mansoni egg excretion was studied in 23 residents of a rural endemic area in North-east Brazil where the over-all prevalence rate was 87% and the peak geometric mean egg excretion was 308 eggs/ml (Bell method) in the 10 to 14-year-old age group. Stool examinations by the Kato method were performed for three to four consecutive days each month for three consecutive months. Both raw and transformed data showed significant stability of S. mansoni egg excretion from day to day and month to month in this population. A single Kato examination detected 68% of individuals who were excreting more than 400 eggs per gramme. Although S. mansoni egg excretion is stable over time, identifying individuals with high egg excretion in endemic populations requires sensitive quantitative methods.

Adolescent

Congenital Chagas's disease in an urban population: investigation of infected twins.

In the Nordeste de Amaralina suburb of Salvador Bahia, Brazil, 47 of 285 pregnant women surveyed had complement fixing antibodies to Trypanosoma cruzi. At delivery T. cruzi was detected in one of 17 placentas from the sero-positive women. The offspring of this case were premature twins and T. cruzi was detected in the peripheral blood of each before death. At autopsy the gastro-intestinal tract and urinary bladder of both were severely affected. Immunofluorescence tests on cord sera, including the single case with T. cruzi in the placenta, were negative for IgM antibodies to T. cruzi. The mother of the infected twins and three of her living children, who were born and have resided in the city, were also infected with T. cruzi. Although the children had visited an area endemic for Chagas's disease for short periods, the mode of transmission in this family may have been transplacental. The value of the immunofluorescence test in the diagnosis of congenital Chagas's disease is discussed.

Antibodies

House construction, triatomine distribution, and household distribution of seroreactivity to Trypanosoma cruzi in a rural community in northeast Brazil.

Household distribution of seroreactivity to Trypanosoma cruzi in inhabitants was analyzed in relation to house construction and the distribution of Panstrongylus megistus, the principal domestic vector of Chagas' disease in a rural area in northeast Brazil. No children residing in mud-brick houses were seroreactive to T. cruzi. The highest rates of seroreactivity occurred in residents of unplastered mud-stick houses, and were twice as high as those found in persons living in mud-brick houses or plastered mud-stick houses. Two-thirds of seroreactive children in this area resided in unplastered mud-stick houses. Over 90% of the P. megistus infestations were found in mud-stick houses. Mud-brick houses had the lowest infestation rates of P. megistus and the lowest household rates of seroreactivity to T. cruzi.

Adult

Trypanosoma cruzi infection in dogs and cats and household seroreactivity to T. cruzi in a rural community in northeast Brazil.

The prevalence of Trypanosoma cruzi parasitemia as determined by xenodiagnosis on domestic dogs and cats was correlated with household rates of seroreactivity to T. cruzi and household Panstrongylus megistus infestation in a rural area in northeast Brazil where P. megistus was the only domiciliary triatomine vector. T. cruzi infection was present in about 18% of domestic dogs and cats. Two-thirds of seroreactive children below age 10 resided in houses with T. cruzi-infected animals. In houses with a T. cruzi-infected dog or cat, as well as at least one infected P. megistus, the household rate of seroreactivity to T. cruzi was five times greater than in houses with non-infected domestic animals and no infected triatomine vectors. Domestic dogs and cats are important reservoirs of T. cruzi in an endemic area where P. megistus is the only domiciliary triatomine vector.

Adult

Clonorchiasis in New York City Chinese.

Among 150 Chinese-born residents of New York City a single stool examination showed 26% were infected with C, sinensis. Most of those infected were immigrants from the Kwangtung Province of China. The possibility of clonorchiasis in Oriental-born residents is emphasized.

China

The intensity and effects of infection with Schistosoma mansoni in a rural community in northeast Brazil.

The intensity of infection with Schistosoma mansoni and its effects were investigated in a defined population living on three contiguous fazendas (subcounties) in a nonmalarious area of northeast Brazil near Salvador, Bahia. Quantitative stool egg counts (Bell technique) were performed on 363 of 417 individuals (90%) of all ages; physical examinations were done on 294 of 357 individuals (82%) 5 years of age and older. The maximum increase in prevalence was observed between the 1- to 4- and 5- to 9-year age groups, while the maximum increase in fecal egg count occurred between 5- to 9- and 10- to 14-year age groups. Highest egg counts were observed in the 10- to 14-year age group (geometric mean of 301 eggs per ml of stool) while the maximum prevalence (100%) was in the 20- to 24-year age group. In the fazenda with the lowest quantitative egg counts the age specific prevalence rates increased more slowly than in the fazendas with higher egg counts. In the study group nearly 50% of the total fecal egg output was accounted for by 22 individuals (6%) who had a mean age of 12.6 years. Egg counts for this selected group were all over 800 eggs per ml of stool with a mean of 1,514 eggs per ml of stool. In children under 15 years of age, the frequency of hepatomegaly and splenomegaly varied directly with the egg count; further, the degree of hepatomegaly was directly correlated with increasing egg counts. No splenic enlargement was noted in children not excreting eggs. In adults, on the other hand, neither splenomegaly nor hepatomegaly could be directly related to schistosomal infection per se. In children, neither the presence of infection with S. mansoni nor its intensity was reflected by altered anthropometric measurements. In the one fazenda tested the frequency of stools positive for occult blood correlated with increasing S. mansoni egg counts.

Adolescent

The epidemiology and household distribution of seroreactivity to Trypanosoma cruzi in a rural community in northeast Brazil.

The prevalence rates and household distribution of seroreactivity to Trypanosoma cruzi by complement fixation (CF) and indirect immunofluorescent antibody methods were determined in a population of 1,087 persons living in a rural area endemic for Chagas' disease in northeast Brazil. There was a gradual rise in the rate of seropositivity to 60% by age 20. Between ages 20 and 55 the prevalence rate remained at about 60%, but declined thereafter. The decline in the older age groups was not accompanied by a fall in geometric mean titer, suggesting that the decline might better be explained by an increased mortality among those seropositive than by a decrease in CF reactivity associated with age. There was variation in the rates of seropositivity in children among the geographic subunits, but the rates among adults were fairly uniform. Household clustering of seropositivity was demonstrated when both household size and age distribution were taken into account. The presence of a seropositive child less than 5 years of age was a good indicator of a household with a high rate of seropositivity; screening for young seropositive children might be a useful tool to locate high risk households. Seropositive children in households where the mother was seropositive but the father seronegative were significantly younger than seropositive children in households where the father was seropositive but the mother seronegative even though the age distribution and the overall rate of seropositivity in both groups of children were similar; thus, conversion to seropositivity earlier in life in children of seropositive mothers may not be due solely to increased exposure, but may indicate that the immunologic response in such children differed from that of children from seronegative mothers.

Adolescent

Letter: Ainhum.

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Ainhum