Designing programs for eliminating canine rabies from islands: Bali, Indonesia as a case study

<p>Background: Canine rabies is one of the most important and feared zoonotic diseases in the world. In some regions rabies elimination is being successfully coordinated, whereas in others rabies is endemic and continues to spread to uninfected areas. As epidemics emerge, both accepted and contentious control methods are used, as questions remain over the most effective strategy to eliminate rabies. The Indonesian island of Bali was rabies-free until 2008 when an epidemic in domestic dogs began, resulting in the deaths of over 100 people. Here we analyze data from the epidemic and compare the effectiveness of control methods at eliminating rabies.</p> <p>Methodology/Principal Findings: Using data from Bali, we estimated the basic reproductive number, R0, of rabies in dogs, to be ~1·2, almost identical to that obtained in ten–fold less dense dog populations and suggesting rabies will not be effectively controlled by reducing dog density. We then developed a model to compare options for mass dog vaccination. Comprehensive high coverage was the single most important factor for achieving elimination, with omission of even small areas (<0.5% of the dog population) jeopardizing success. Parameterizing the model with data from the 2010 and 2011 vaccination campaigns, we show that a comprehensive high coverage campaign in 2012 would likely result in elimination, saving ~550 human lives and ~$15 million in prophylaxis costs over the next ten years.</p> <p>Conclusions/Significance: The elimination of rabies from Bali will not be achieved through achievable reductions in dog density. To ensure elimination, concerted high coverage, repeated, mass dog vaccination campaigns are necessary and the cooperation of all regions of the island is critical. Momentum is building towards development of a strategy for the global elimination of canine rabies, and this study offers valuable new insights about the dynamics and control of this disease, with immediate practical relevance.</p&gt

Bentuk dan Sebaran Lesi Demodekosis pada Sapi Bali (THE SHAPE AND DISTRIBUTION OF DEMODECOSIS LESIONS ON BALI CATTLE)

Demodicosisis a skin diseasecaused byDemodexsp., that inhabits animal hair folliclesandcandamageskintissue. This study aims to reveal the form and distribution of demodicosis lesions in Bali cattle in thecenter of breeding bali cattle Sobangan. The sample was recorded based on the present of skin lesions.Skin scraps were collected, and examined for Demodex sp. The shape of the lesions was documented byobserving existing lesions on the body of bali cattle. The size of the lesions was measured using calipers.The distribution of the lesions was done by dividing the body area of head, neck, back, and abdomen region.We found that the prevalence of demodicosis was 12.66% (38/300). The shape of demodicosis lesions werenodular, scab, and dollar plaque. Distribution of demodicosis lesions was mostly at the neck (36.8%), atthe back (34.21%), and neck to back (23.68%). In conclusion, the prevalence of demodicosis was mild, andthe greatest distribution was on neck. In order to reduce the incidence rate in bali cattle should be keptproperly and sanitation is carried out at a good standard

Tingkat Kejadian Rabies Dan Pemetaan Status Desa Tertular di Kecamatan Mengwi, Badung, Bali Tahun 2015

Penelitian ini bertujuan untuk mengetahui tingkat kejadian rabies dan titik koordinat kejadian rabies di Kecamatan Mengwi periode 2015. Tingkat insiden rabies dianalisis secara deskriptif kuantitatif dengan menggunakan program Microsoft Excel dan untuk keperluan pemetaan kasus digunakan software Quantum-GIS. Dalam penelitian ini digunakan 2 jenis data yaitu data primer yang didapatkan dengan cara menentukan titik koordinat dimana ditemukannya lokasi kasus positif rabies pada anjing yang telah terkonfirmasi rabies di laboratorium dan data sekunder berupa data kasus anjing rabies dan jumlah populasi anjing di Kecamatan Mengwi Kabupaten Badung. Tingkat kejadian rabies di Kecamatan Mengwi periode Januari hingga Agustus 2015 sebesar 0,17%. Dari 20 desa yang ada di Kecamatan Mengwi enam desa di antaranya ditemukan kejadian rabies, yaitu pada April 2015 ditemukan di koordinat 115o 16’ 85” BT dan 8o 54’ 58” LS yang berada di Desa Mengwi, pada Mei 2015 ditemukan di titik 115o 16’ 15” BT dan 8o 56’ 71” LS yang berada di Desa Mengwitani, pada Juli 2015 ditemukan di tiga titik berbeda yaitu di koordinat 115o 17’ 66” BT dan 8o 57’ 78” LS yang berada di Desa Kapal, 115o 17’ 50” BT dan 8o 59’ 26” LS yang berada di Desa Abianbase, koordinat 115o 12’ 46” BT dan 8o 62’ 25” LS yang berada di Desa Munggu, sedangkan pada Agustus 2015 kejadian rabies ditemukan di dua titik yang berbeda yaitu di koordinat 115o 15’ BT dan 8o 59’ LS yang berada di Desa Abianbase, koordinat kedua ditemukan di 115o 17’ 75” BT dan 8o 52’ 30” LS yang berada di Desa Werdi Bhuwana

Key epidemiological and operational variables determining the success of rabies vaccination programmes in terms of the predicted probability of eradication (grey y–axis and line) and time to eradication (black y–axis, medians and 95% PI), showing sensitivity to: (A) the basic reproductive number, <i>R</i>₀, (B) vaccination coverage (achieved at the time and location of the campaign (see Fig. 4)), (C) annual dog population turnover, with conversion into birth/death rate assuming constant population size (birth rates equal to death rates), and (D) duration of immunity provided by vaccine.

<p>Based on 1000 simulations generated using parameters in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002372#pntd-0002372-t001" target="_blank">Table 1</a> (unless specified) and annual campaigns of the ‘random’ mass vaccination strategy (<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002372#pntd-0002372-t002" target="_blank">Table 2</a>).</p

Model description.

<p>(A) Secondary cases are drawn from the (i) offspring distribution, and become infectious at a date drawn from the (ii) generation interval distribution: here four secondary cases are generated by the index case (black dot) which become infectious on day 14, 21, 23, and 35. The occurrence of secondary cases depends on vaccination coverage in the grid cell at the time of transmission. (iii) With probability 1–<i>p</i> each offspring occurs at a location generated from the local dispersal kernel (solid black arrows). (iv) With probability <i>p</i>, each offspring occurs on any randomly chosen grid cell (broken black arrow). It took 2.2 years for rabies to be detected in all nine Regencies (grey band), consistent with <i>p</i> = 0.05–0.09 (black dots are medians with 95% PIs from 100 simulations). See <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002372#pntd-0002372-t001" target="_blank">Table 1</a> for parameterization of distributions. (v) Human rabies deaths versus confirmed dog rabies cases, showing the best-fit relationship (black line, see <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002372#s3" target="_blank">Results</a> for equation) and 95% confidence intervals (grey area). (B) 95% PI envelope of simulated cases (grey area) with annual campaigns of the ‘random’ mass vaccination strategy (green line, <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002372#pntd-0002372-t002" target="_blank">Table 2</a>), which is rolled out when cumulative cases reach 7,000 and from which point the time to eradication is measured.</p

Vaccination strategies.

<p>The probability of eradication following: (Ai) 1; (Aii) 2; (Aiii) 3 campaigns under a range of coverages (40, 60, 80%) and inter–campaign intervals (0, 6, 12 months); (Aiv) vaccination as implemented on Bali, and projected from January 2012 when rabies was still circulating. The time to eradication (medians with 95% PI) for a range of: (B) frequencies of human–mediated transport of dogs (<i>p</i> = 0, 0.02 or 0.05) and campaign strategies (<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002372#pntd-0002372-t002" target="_blank">Table 2</a>). 95% PI of the one-month ‘sync’ strategy is highlighted (grey band) for comparison with the six–month strategies; (C) coverages when campaigns last 1 month or 6 months. (D) The probability of eradication with % island area left unvaccinated, made up of either randomly chosen 1 km squares (solid lines) or randomly chosen blocks, and when human-mediated movement of dogs was either infrequent (<i>p</i> = 0.02, grey) or frequent (<i>p</i> = 0.05, black).</p

Parameters values and distributions used to model rabid dog movement and transmission processes.

<p>Parameters values and distributions used to model rabid dog movement and transmission processes.</p

Trajectories of vaccination coverage achieved at the island-wide level during modeled vaccination campaigns and in relation to levels of coverage required for herd immunity.

<p>Three types of coverage are referred to in the text: target coverage achieved in the subset of the population at the time and location of a local campaign (i.e. within a block); island-wide vaccination coverage (y-axis); and critical vaccination coverage (<i>P_crit</i>) which is required for herd immunity and is determined by <i>R</i>₀, the basic reproductive number of rabies in Bali, <i>P_crit</i> = 1-(1/<i>R</i>₀). <i>R</i>₀ estimated for Bali is 1·2, which corresponds to a <i>P_crit</i> of 17% (grey solid line). A 40% coverage campaign resulted in a trajectory that stayed above 17% (black solid line) and the probability of eradication was 1 (<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002372#pntd-0002372-g003" target="_blank">Fig. 3B</a>), whereas 30% coverage resulted in a trajectory that dipped below 17% (black dashed line) and the probability of eradication was less than 1 (<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002372#pntd-0002372-g003" target="_blank">Fig. 3B</a>). Annual campaigns were modeled, using parameters in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002372#pntd-0002372-t001" target="_blank">Table 1</a> and the ‘random’ six-month strategy (<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002372#pntd-0002372-t002" target="_blank">Table 2</a>). Blocks are assumed to be vaccinated at the end of the month hence coverage increments jaggedly. Coverage declines between vaccinations due to waning of immunity and dog population turnover.</p

Modelled vaccination strategies.

<p> All campaigns were annual unless specified in the analyses.</p

Rabies incidence and spread in Bali prior to island-wide mass vaccination.

<p>(A) Cases in humans and dogs and corresponding control efforts. (B) The month that rabies was first confirmed in each village. The black dot marks the village where the index case occurred. Regencies are outlined in black.</p