UniLogistic: A SAS Macro for Descriptive and Univariable Logistic Regression Analyses

Descriptive and univariable logistic regression analyses are essential before constructing multivariable models, but are very time consuming, particularly if a large number of explanatory variables are to be evaluated. A macro UniLogistic is described in this paper that conducts descriptive and univariable logistic regression analyses (binomial, ordinal or nominal, as required) in SAS and presents results in formatted tables in Excel and graphics in PDF files. Implementation of the macro is illustrated in this paper using example datasets from statistics and epidemiology textbooks

Assessment of the proportion of under-reporting during the 2007 equine influenza outbreak in New South Wales, Australia.

During the 2007 equine influenza (EI) outbreak in Australia, there was no objective information about the possible under-reporting of cases by horse owners either so that they would avoid movement restrictions or because of their inability to detect infection. This investigation aimed to estimate the proportion of underreporting during the outbreak based on the results of surveillance undertaken in conjunction with vaccination. The results provided improved estimates of morbidity during the outbreak and indicated the level of under-reporting likely to occur in future outbreaks of other infectious diseases in horses in Australia. Keywords: disease control program; epidemiology; equine influenz

Attack risk on infected properties during the 2007 equine influenza outbreak in New South Wales, Australia

Abstract The aim of this preliminary study was to estimate the proportions of seropositive horses on infected premises (IPs) in order to assess the attack risk of the disease. Logistic regression analyses were conducted to evaluate the differences in attack risks between enterprise sizes and predefined spatial clusters/regions. The average attack risk experienced during the outbreak was 96.88% (median 100%) but it differed according to the size of the enterprise and other geographical and demographic conditions. The highest attack risks were observed in the Dubbo cluster/region and the lowest in the Narrabri–Northern cluster. Properties with fewer horses were generally more likely to have higher attack risks than larger enterprises though this was not true for all cluster/region. Keywords equine influenza, epidemic, seroprevalenc

Assessment of the proportion of under-reporting during the 2007 equine influenza outbreak in New South Wales, Australia.

During the 2007 equine influenza (EI) outbreak in Australia, there was no objective information about the possible under-reporting of cases by horse owners either so that they would avoid movement restrictions or because of their inability to detect infection. This investigation aimed to estimate the proportion of underreporting during the outbreak based on the results of surveillance undertaken in conjunction with vaccination. The results provided improved estimates of morbidity during the outbreak and indicated the level of under-reporting likely to occur in future outbreaks of other infectious diseases in horses in Australia. Keywords: disease control program; epidemiology; equine influenz

Attack risk on infected properties during the 2007 equine influenza outbreak in New South Wales, Australia

Abstract The aim of this preliminary study was to estimate the proportions of seropositive horses on infected premises (IPs) in order to assess the attack risk of the disease. Logistic regression analyses were conducted to evaluate the differences in attack risks between enterprise sizes and predefined spatial clusters/regions. The average attack risk experienced during the outbreak was 96.88% (median 100%) but it differed according to the size of the enterprise and other geographical and demographic conditions. The highest attack risks were observed in the Dubbo cluster/region and the lowest in the Narrabri–Northern cluster. Properties with fewer horses were generally more likely to have higher attack risks than larger enterprises though this was not true for all cluster/region. Keywords equine influenza, epidemic, seroprevalenc

Anthropogenic and environmental risk factors for rabies occurrence in Bhutan.

Anthropogenic and environmental factors were assessed as predictors of sub-districts in Bhutan that reported rabies in domestic animals during the period 1996−2009. Rabies surveillance data were retrieved from the Veterinary Information System database. Anthropogenic and environmental information were obtained from public data sources. Using the total number of rabies cases reported in domestic animals, the 205 sub-districts of Bhutan were categorized as those sub-districts that reported rabies and those that did not report rabies (n=146). Logistic regression models were fit to the data and odds ratios and 95% confidence intervals were estimated. Sub-districts that share a border with India (OR 10.43; 95% CI: 4.42–24.64; P<0.001); sub-districts connected by major roads (OR 3.09; 95% CI: 1.24–7.68; P=0.015); and greater human population density (OR 3.26; 95% CI: 1.48–7.21, P=0.003) were significantly associated with a sub-district reporting animal rabies in Bhutan during 1996−2009. Results suggest that human population characteristics play an important role in rabies occurrence. Keywords: Rabies, domestic animals, anthropogenic and environmental risk factors, Bhuta

Human rabies post exposure prophylaxis in Bhutan, 2005-2008: Trends and risk factors.

The aim of this study was to understand the use and distribution of human rabies post exposure prophylaxis (PEP) vaccine in Bhutan and to identify risk factors for receiving an incomplete course of the vaccine. We analysed post exposure treatment records from 28 medical hospitals from 2005 to 2008. Males (59%) accounted for significantly more PEP events than females (41%) across all age groups (P 2800 events, respectively. Significantly (P < 0.001) more PEP events were reported from the southern parts of Bhutan that are endemic for rabies or those areas in eastern Bhutan that have reported rabies outbreaks than other parts of Bhutan. Forty percent (n = 3360) of the patients received an incomplete course of vaccine (<5-doses of vaccine intramuscular). Results suggest that patients with animal bite injury were less likely to receive an incomplete vaccine course than non-bite recipients, and patients presented to hospitals in rabies endemic or outbreak areas were less likely to receive an incomplete course than in non-rabies areas or rabies free areas. Similarly, patients presenting to hospitals for PEP during spring and summers months were less likely to receive an incomplete vaccine course than those during other seasons. Public education campaigns need to be conducted in Bhutan to reduce dog bite incidents and also to prevent mass exposures to rabies. A thorough assessment of each individual case based on the WHO guidelines would reduce unnecessary PEP (and therefore costs) in Bhutan

Patterns of Rabies Occurrence in Bhutan between 1996 and 2009

This study was conducted to evaluate incidence and seasonal trends of rabies in dogs and other domestic animals in Bhutan from 1996 to 2009. Time series analysis approach was used to determine the seasonal trend and temporal association between species-specific rabies cases in animals. A total of 814 rabies cases were reported during the 14-year period, of which cattle and domestic dogs accounted for 55% (447/814) and 39% (317/814) of the cases, respectively. The remaining 6% of the cases (50/814) were reported in horses (2%), cats (2%), pigs (1%) and goats (1%). Rabies cases were reported throughout the year with more reports during spring and summer months. The annual patterns of cases were stable from 1996 to 2005, but the incidence increased during 2006 and 2008. Fifty-nine of the 205 sub-districts reported rabies in animals from 1996 to 2009 with increased incidences in the four districts in southern Bhutan, an area located close to the border towns of India. A significant (P < 0.05) positive cross-correlation was observed between the number of cases in dogs and other domestic animals at time lags (months) 1–3 with the highest correlation (r = 0.94, P < 0.05) observed at time lag 0 (same month) indicating that the peak in rabies incidences occur in the same month when both dogs and other domestic animal cases are reported. Regression analysis predicted rabies in other domestic animal when there are reports of rabies in dogs during the previous months. This study provides useful information about the epidemiology of rabies that can be used to plan a rabies control programme in Bhutan. Keywords: Rabies; domestic animals; surveillance; time series analysis; Bhutan Impacts This study evaluated rabies incidence and seasonal trends in domestic animals in Bhutan from 1996 to 2009. Rabies cases in animals were reported throughout the year with a higher incidence during spring and summer months. The number of reported cases was stable from 1996 to 2005 but increased in 2006 and 2008. Fifty-nine of the 205 sub-districts reported rabies between 1996 and 2009, with a higher incidence in southern Bhutan. There was a positive temporal correlation between the number of cases reported in dogs and other domestic animals

Identification of risk factors for OJD infection-level in sheep flocks.

The level of clinical disease experienced due to ovine Johne’s disease (OJD) appears to vary considerably between infected sheep flocks in Australia, even for flocks in the same locality that appear to have similar characteristics. This has led to speculation on the cause. Risk factors for the severity of OJD were identified in this project. They were related to some farming practices such as fertiliser application, as well as to flock management and soil type. In particular weaner management and nutrition of sheep to hogget stage were important factors that producers can optimise to reduce the impact of OJD. High soil fertility, organic matter and clay content were also important factors associated with higher levels of OJD. There was less OJD associated with sandy soils. Further research is required in order to determine how these soil characteristics affect the prevalence of OJD and how best to manage soil and pasture to mitigate the losses due to OJD