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Biomedical subjects

A S Muller

Publications and source records attributed to A S Muller.

30 records · Page 2Linked to original sources
PubMed1977

Poliomyelitis: epidemiology and prophylaxis. 5. Results of a two- and three-dose vaccination experiment.

In tropical countries, seroconversion rates following oral poliomyelitis vaccination are frequently unsatisfactory. In an area of the Machakos district in Kenya, 4000 children under 5 years of age have been registered and are visited fortnightly by trained field staff as part of a comprehensive, population-based, longitudinal surveillance project. It was considered possible that poliomyelitis vaccine, given orally to children twice or three times at home, would produce satisfactory conversion rates. After collection of blood from a random sample of the children, vaccine was given twice to all children under 5 years of age. Blood was then collected a second time from a different sample of children. After a third dose of vaccine, a third blood collection followed. The percentages of the children that received vaccine each round were calculated and the sera tested for antibodies. It appeared that the mean titre was more strongly related to age than to the number of doses of poliomyelitis vaccine received. Improvement of herd immunity after two vaccine distributions was significant for a few age groups and for two types of vaccine only. In none of the groups was a significant improvement obtained by the third vaccine distribution. The problems associated with vaccination by live poliomyelitis vaccine in tropical countries are discussed in relation to the results.

Age Factors↗
PubMed1977

Machakos project studies. Agents affecting health of mother and child in a rural area of Kenya. II. The diagnosis of measles under field conditions.

The measles signs of children reported for measles were recorded on a check list of clinical signs. The presence and absence of these signs for a measles group (M) and a control group (C) were subject of a statistical analysis. The M and C group were determined by the results of laboratory determinations. A prediction score was derived by means of minimal paths analysis, used in reliability networks. The clinical score, based on certain criteria, the prediction score and the result of laboratory determinations were combined in order to reach a final diagnosis. A comparison of the clinical diagnosis and the final diagnosis showed a considerable overlap of the two diagnoses. The conclusion was that the clinical diagnosis only is sufficient to reach adequate incidence rates in the case of a measles epidemic.

Child↗
PubMed1977

Agents affecting health of mother and child in a rural area of Kenya. III. The epidemiology of measles.

Between April 1974 and March 1976 surveillance of measles has been conducted by 12 fieldworkers making fortnightly home visits among a total population of 24,000 living in nearly 4000 households scattered in variable density throughout an area of 87 sq km in the northern division of the Machakos district, Kenya. The diagnosis of measles was verified by one of the project's physicians according to standardized procedures and was, whenever possible, supported by virus isolation and serum antibody level determination. Because not all reported patients were actually seen during the period of clinical manifestations, the diagnosis remained doubtful in a number of cases. Incidence and mortality figures have been estimated with 95% confidence limits based on the assumption that doubtful cases represent a probability of measles of .33 and probable cases a probability of .67. The estimated attack rate for the susceptible population 0-15 years of age was 13.5%. When related to all children--susceptible or not--the attack rate was highest in the 1-2 years age group (11%). Almost 15% of cases occurred below the age of one year, 1% below 6 months of age and 6% between 6 and 8 months. The estimated case fatality rate was 6.5%, fatality being highest between 1 and 2 years of age. For the age group 0-15 years measles accounted for 16.7% of all deaths. The estimated death rate per 100,000 total population was 113. The epidemiological pattern of measles suggests continuous re-introduction of the measles virus in a dispersed population causing micro-outbreaks of the disease in geographically widely separated spots throughout the year which tends to keep the proportion of susceptibles down and the attack rate during a protracted epidemic relatively low.

Adolescent↗
PubMedDate not supplied

A prospective sero-epidemiological study of visceral leishmaniasis in Baringo District, Rift Valley Province, Kenya.

The incidence of visceral leishmaniasis (VL) was studied in 30 clusters with an average of 98 individuals in each cluster in a defined, endemic rural area of Baringo District, Kenya. The clusters were centred around recent cases of VL. Anti-leishmanial antibodies were measured by the direct agglutination test (DAT) and a clinical examination was performed on 2 occasions between April 1991 and May 1993. Of 2934 individuals tested by the DAT during the first visit, 78 (2.7%) were seropositive, 54 with and 24 without a history of VL. The seroconversion rate was 9/1000 person-years of observation (95% confidence interval 5.1-12.92) among 2332 seronegative individuals retested the following year. During the entire study period, VL was diagnosed in 10 patients, with an incidence rate of 2.2/1000 person-years of observation (95% confidence interval 0.8-3.6). Household contacts of individuals with previously confirmed VL had a higher frequency of DAT positivity than the rest of the population. This difference was significant for both sexes. These results suggest transmission in and around houses.

Adolescent↗
PubMedDate not supplied

Visceral leishmaniasis: use of the polymerase chain reaction in an epidemiological study in Baringo District, Kenya.

The polymerase chain reaction was applied to capillary blood spots dried on filter paper from 20 parasitologically proved cases of visceral leishmaniasis (VL), 21 subclinical cases, and 11 healthy controls in a longitudinal study of anthroponotic VL in Baringo District, Kenya. Leishmania deoxyribonucleic acid (DNA) was detected 10.5 months before diagnosis and up to 3 years after diagnosis and apparently successful treatment. Subclinical cases can have detectable circulating parasite DNA in their blood. These findings may indicate that subclinical cases can be a reservoir and formerly treated VL patients can remain a reservoir for a long time. Xenodiagnosis should be performed on subclinical cases and former VL patients to establish their role in transmission of VL in Kenya.

Adolescent↗