Spatial and temporal distribution of selected canine cancers in Michigan, USA, 1964-1994.

Although rates are commonly used to compare regional disease occurrence, rate-independent methods might also be useful in circumstances where geographic occurrence of a disease is known, but calculation of disease rates is not feasible. This is frequently the case for diseases in companion animals, where accurate enumeration of populations-at-risk is often arduous. This study had two objectives: to demonstrate a rate-independent method for investigating disease aggregation in companion animals; and, to assess the spatial and temporal clustering of canine cases of four cancers that are biologically similar in dogs and humans. Geographic information systems and point-pattern analysis were used to assess the spatial and temporal clustering of incident cases of four types of canine cancer in three counties in Michigan between 1964 and 1994, and to generate hypotheses concerning disease aggregation. Significant (P < or = 0.01) spatial clustering was found that varied by county and cancer type. No definitive temporal patterns could be deduced from a temporal analysis of the cases of canine cancer in this study. These results demonstrate distance-based methods for assessing clustering of disease, and suggest that processes determining the aggregation of canine cancer cases do not act in a spatially uniform manner.

Epidemiology of acute leukaemia in the Cape Province of South Africa.

Of 535 consecutive cases of acute leukaemia diagnosed in the Cape Province between 1978 and 1985, demographic data are incomplete in 75 black patients and they have had to be excluded from the spatial analysis. Of the remaining 460 cases, 223 (48.5%) occurred in white patients and 237 (51.5%) in those of mixed ancestry, classified as coloureds according to the Population Registration Act No. 30 of 1950. The average incidence was 2.12, 1.37 and 0.58/100,000 for whites, coloureds and blacks respectively. There was no temporal trend in the incidence of acute leukaemia between the three race groups. The median age for whites was 30 years and for the coloureds was 15 years, which is comparable to the 16 years for the black patients. The two-peak age distribution for leukaemia was seen in the white group, but was absent in the other two groups. This is accounted for by a different distribution in non-lymphoblastic as opposed to lymphoblastic subtypes. Furthermore, there was a disproportionately high frequency of acute progranulocytic leukaemia in the black patients, whereas the white and coloured groups were similar. There was a single, clearly defined macro-scale cluster restricted to white patients in Statistical Region 17 (SR-17). This exploratory study provides the first epidemiologic data for acute leukaemia in the Cape Province. It needs to be extended in order to verify these observations under more controlled circumstances and to seek evidence for some environmental factors that may account for the geographical cluster.

The community perinatal health care system of urban Cape Town, South Africa--I. Characteristics of mothers and birth outcomes.

Greater Cape Town has developed a geographical network of perinatal health care services for low-income mothers using community-based clinics with hospital referrals. This study analyzes 25,409 births recorded in 162 different urban residential areas during 1987. The data apply to two populations--black and mixed. Information on the mother, such as height, weight, education, parity, and prenatal visits is indicated by suburb, as well as birth outcomes such as gestational age, birthweight, and method of obstetrical delivery. Comparisons are drawn between black and mixed populations and among suburbs. High utilization rates and successful maternity and infant outcomes suggest that the outreach clinics of Cape Town could provide a model for urban agglomerations in other African countries.

The community perinatal health care system of urban Cape Town, South Africa--II. Geographical patterns.

Greater Cape Town has developed a geographical network of perinatal health care services for low-income mothers using community-based clinics with hospital referrals. This study analyzes 25,409 births recorded in 162 different urban residential areas during 1987. The data apply to two populations--black and mixed. Information on the mother, such as height, weight, education, parity, and prenatal visits is indicated by suburb, as well as birth outcomes such as gestational age, birthweight, and method of obstetrical delivery. Comparisons are drawn between black and mixed populations and among suburbs. High utilization rates and successful maternity and infant outcomes suggest that the outreach clinics of Cape Town could provide a model for urban agglomerations in other African countries.

The geographical variation in neonatal and post-neonatal mortality in South Africa, 1978-1982.

Early neonatal, neonatal and post-neonatal mortality rates were systematically calculated according to the statistical regions of South Africa for the white and coloured populations over a 5-year period. The geographical variation is wide and the statistical significance in these mortality rates for coloured infants in rural areas of the Cape and the Orange Free State are particularly high and call for urgent attention.

The spatial variation of mortality among children under 5 years of age in South Africa.

Childhood mortality rates between 1 and 4 years and under 5 years of age were systematically calculated according to the statistical regions of South Africa for the white and coloured populations. The geographical variation is wide and the statistical significance in these mortality rates is presented in map form. Mortality rates are particularly high in rural areas. For the coloured group, the correlation between the spatial distribution of infant mortality rates under 1 year of age and the 1-4 year mortality rate pattern was high.

Perinatal health in the peri-urban township of Khayelitsha, Cape Town. Part I. Mothers and their newborn infants.

The satellite 'city' of Khayelitsha lies some 40 km south-east of the centre of metropolitan Cape Town. The first phase of the development, Town 1, including a large 'squatter' area, accommodates approximately 150,000 people at present. It is envisaged that ultimately the entire 3,200 ha site will house between 250,000 and 350,000 people. In order to obtain useful planning information for future community obstetric and neonatal health care services, a survey of all births within the Peninsula Maternal and Neonatal Service (PMNS) during 1986 was undertaken. Of a total of 2,113 mothers from Khayelitsha, 2,000 (94.7%) gave birth to a live singleton infant. The mean maternal age was 26.2 years, 15.1% of mothers being under 20 years of age. The mean parity was 3.03, and 18.3% of mothers were having their first baby. Only 3.1% of mothers booked early (in the first trimester); however, 91.9% were booked before delivery. The average number of prenatal visits was 3. The largest proportion of mothers (43.1%) delivered at the Heideveld midwife obstetric unit (MOU). There was an overall pre-term rate of 7.6%, while 8.8% of infants were of low birth weight (LBW) (less than 2,500 g). In addition, 51.4% of the LBW infants were born at term. The mean birth weight was 3,160 g. The largest proportion of mothers (53.6%) were residents of the 'squatter' area. No statistically significant differences in obstetric features, maternal characteristics and pregnancy outcome were discernible between the squatter, site-and-service, and core housing areas of Khayelitsha, with the exception of higher maternal weight, earlier booking and more antenatal visits in the group from the core housing area.

Perinatal health in the peri-urban township of Khayelitsha, Cape Town. Part II. Infant mortality.

Estimates of infant mortality suggest that the rate during the past 14 years for families living in Khayelitsha at present was approximately 130-160/1,000. In contrast, the infant mortality rate for infants born in Khayelitsha during 1986 was 50.3/1,000. The highest rates occurred in the post-neonatal period in 'squatter' families, infection being a common cause of death. Mortality rates should fall further with improved housing.

The spatial distribution of infant mortality rates in South Africa, 1982.

Infant mortality rates (IMRs) systematically calculated for the statistical regions of South Africa are presented for those groups of the population for which birth and death data are routinely collected. The geographical variation in the IMR and its statistical significance is presented in a series of maps. A more detailed analysis is also provided for the larger metropolitan areas.

Characteristics of infant mortality in the RSA 1929-1983. Part I. Components of the white and coloured infant mortality rate.

Secular trends in white and coloured neonatal, post-neonatal and infant mortality rates are presented for the period 1929-1983. More detailed information is given for deaths in the first month of life. During this 54-year period the infant mortality rate for whites has declined from 64.2/1,000 to 13.5/1,000, whereas the rate for coloureds fell from 158.8 (1938) to 55.0/1,000. The greater part of the latter decline occurred after 1970. Since 1945 the neonatal mortality rate (NMR) for whites has exceeded the post-neonatal mortality rate (PNMR) but among coloureds the PNMR still exceeds the NMR.

Characteristics of infant mortality in the RSA 1929-1983. Part II. Causes of death among white and coloured infants.

The relative contribution of different causes of death in the first year of life is presented for the period 1929-1983. Infections and perinatal and respiratory causes most commonly result in infant death among coloureds, while perinatal and congenital causes are commonest among whites. Over the 54-year period studied the mortality rate due to infections has fallen dramatically among whites but much less so among coloureds. The two causes of death for which the ratios of coloured to white mortality are highest, viz. infections (28 times) and respiratory causes (9 times), are those which have the greatest post-neonatal mortality component.

Variations in mortality of the coloured, white and Asian population groups in the RSA, 1978-1982. Part V. Hypertensive diseases.

An analysis was undertaken of mortality from hypertensive disease in the RSA between 1978 and 1982 among whites, coloureds and Asians. The age-specific mortality rates for each group are presented and comparisons are also made between these groups based on age-standardised mortality rates. As with a similar study undertaken for the period 1969-1971, marked variations are seen between the various population groups. The rates for Asians exceeded those for coloureds substantially, and both these groups had far higher rates than whites. These results demonstrate an interesting variation when compared with mortality from ischaemic heart disease and recent prevalence studies of hypertension. The possibility that this variation is due to better control of hypertension in whites or is a result of a different ratio of risk factors in each group studied is considered.

Variations in mortality of the coloured, white and Asian population groups in the RSA, 1978-1982. Part VI. Ischaemic heart disease.

An analysis of ischaemic heart disease (IHD) mortality for the period 1978-1982 showed markedly different rates for the Asian, white and coloured population groups in the RSA. Age-specific and age-standardised rates for Asians were in general considerably higher than those for whites, and did not show the marked decline with time observed in rates for whites. Although coloureds were seen to have considerably lower age-standardized rates than Asians or whites of the same sex, an increase in the age-standardised rates for coloured males over a 10-year period and a slight decrease among females suggested that rates for coloureds may be in the process of approaching those for the other groups. The observed decline in IHD rates among whites of both sexes suggests that preventable major risk factors may be coming under control, apparently to a greater extent in this group than among Asians or coloureds.

Variations in mortality of the coloured, white and Asian population groups in the RSA, 1978-1982. Part II. Cerebrovascular disease.

An analysis was undertaken of mortality from cerebrovascular disease in the RSA between 1978 and 1982 in whites, coloureds and Asians. This article details the age-specific mortality rates for each group and also comparisons between groups based on age-standardised mortality rates. Marked differences are seen between the various population groups, the rates for Asians and coloureds (particularly females) far exceeding that for whites. Comparison of these data with those published previously by Wyndham suggest that while mortality from this cause may be falling among whites and Asians, the rate is remaining relatively static in the coloured population.

Variations in mortality of the coloured white and Asian population groups in the RSA, 1978-1982. Part III. Rheumatic heart disease.

An analysis was undertaken of mortality from rheumatic heart disease in the RSA between 1978 and 1982 in whites, coloureds and Asians. This article details the age-specific mortality rates (MRs) for each group and also comparisons between groups based on age-standardised MRs. The rates for Asians and coloureds markedly exceed those for whites, particularly in the lower age groups (under 45 years).