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Biomedical subjects

R H Morrow

Publications and source records attributed to R H Morrow.

At least 37 records · Page 2Linked to original sources
PubMed1983

Relationship of electrocardiographic abnormalities and seropositivity to Trypanosoma cruzi within a rural community in northeast Brazil.

The relationship of infection with Trypanosoma cruzi to ECG abnormalities was studied in a defined population in rural Bahia, Brazil. Of 644 individuals 10 years of age or older who had complement fixation tests for antibodies to T. cruzi and ECGs, 53.7% were seropositive. ECG abnormalities were more common in seropositive individuals than in seronegative individuals, and more common in men than in women. The peak prevalence rate of abnormal ECGs occurred among seropositive individuals between 25 and 44 years of age; in this age group ECG abnormalities occurred 9.6 times more frequently among seropositive individuals than among seronegative individuals. The most common abnormalities were ventricular conduction defects, and right bundle branch block with or without fascicular block occurred in 10.7% of the infected population. PR intervals were longer in seropositive individuals than in seronegative individuals. Ventricular extrasystoles were slightly more common in seropositive individuals. A declining prevalence rate of abnormal ECGs among older seropositive individuals suggested selective mortality due to Chagas' heart disease.

Adolescent↗
PubMed1978

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↗
PubMed1977

Further studies of space-time clustering of Burkitt's lymphoma in Uganda.

All hospital-treated cases of Burkitt's lymphoma (BL), with onset of symptoms in the period 1963-68 and resident in the Lango and Acholi districts of Uganda, were identified. The average annual incidence of BL in the 6-year period was 1-87 X 10(-5), similar to that in the adjacent West Nile district. Contrary to findings in other areas of Uganda, there was no evidence of seasonal variation in the onset of cases, nor of space-time clustering, nor of a decline in the incidence of BL in the study period. An inverse relationship was noted between the median age at onset of BL and the incidence of the disease in different areas of Uganda, a finding consistent with intense malarial infection being a precipitating factor for BL. The variable observations with respect to space-time clustering of BL and seasonal variation in incidence in different areas remains unexplained, but it is suggested that a closer study of the patterns of malarial infection in these areas may help to account for the findings.

Age Factors↗
PubMed1976

Burkitt's lymphoma in the Mengo Districts of Uganda: epidemiologic features and their relationship to malaria.

An epidemiologic study of 123 patients residing in the Mengo Districts of Uganda, with onset of symptoms of diagnosed Burkitt's lymphoma (BL) in the period 1959-68, revealed a substantial decline in incidence of BL during that decade. Other significant findings included differences by ethnic group in age of patient at onset of BL, a change in the proportions of patients by ethnic group over the decade, a lower incidence rate of BL in the countries of higher altitude, and a seasonal pattern of onset. There was no evidence of the time space clustering previously reported for BL in Uganda. The changing pattern of BL in the Mengo Districts was consistent with the hypothesis that severe malaria infection not only is important in the development of BL but also precipitates onset.

Adolescent↗
PubMed1976

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↗
PubMed1976

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↗
PubMed1976

Experimental alimentary infection of anole lizards (Anolis carolinensis) with Mycobacterium ulcerans.

Pathogenic Mycobacterium ulcerans were recovered from the stool of anole lizards up to 11 days after inoculation by stomach tube. M. ulcerans was isolated from the liver of 3 of 20 lizards and acid fast bacteria were seen in the mucosa of intrahepatic bile ducts in 2 of these 10 weeks post-inoculation. These results provide equivocal support for our hypothesis that herpetofauna are a reservoir of infection with M. ulcerans.

Administration, Oral↗
PubMed1976

Epstein-Barr virus-malaria interaction models for Burkitt's lymphoma: implications for preventive trials.

Infections with both Epstein-Barr virus (EBV) and malaria have been implicated as causal factors in the pathogenesis of Burkitt's lymphoma (BL). Proposed trials of preventive measures for both infections are receiving serious consideration as possible means of establishing a causal relationship with BL. In this paper we examine certain models for the interaction of EBV and malaria in the induction of BL, and also review the aims of the longitudinal, population-based study being conducted in the West Nile District of Uganda. Given existing knowledge, the outcome of preventive trials, even for the most simple interaction models, is unpredictable and, under certain circumstances, trials of an EBV vaccine could actually increase the incidence of BL. It is suggested that trials of an EBV vaccine at this time would be premature and should be delayed at least until the results from the West Nile prospective study are clear.

Age Factors↗
PubMed1975

Experimental infection of anole lizards (Anolis carolinensis) with Mycobacterium ulcerans by the subcutaneous route.

To test whether herpetofauna could be a laboratory model for Mycobacterium ulcerans, 21 anole lizards were inoculated subcutaneously with viable M. ulcerans, 21 with autoclaved organisms, and 14 with an aqueous solution of 0.01% Tween 80. M. ulcerans was recovered in culture from the slowly progressive lesions which developed at the inoculation site in lizards receiving the viable bacteria. Progressive lesions did not occur in the two control groups. Three patterns of inflammatory response to viable M. ulcerans were observed: 14 lizards developed a diffuse, granulomatous reaction in which acid fast bacilli (AFB) were predominantly intracellular; 1 developed focal, encapsulated granulomas; 5 developed a diffuse, necrotizing granulomatous response in which most AFB were extracellular--similar to the characteristic lesion found in human infections.

Animals↗