Using Integrated Bite Case Management to estimate the burden of rabies and evaluate surveillance in Oriental Mindoro, Philippines.

Background: Despite national elimination efforts, dog-mediated rabies remains endemic in the Philippines. Free provision of post-exposure prophylaxis (PEP) through the widespread establishment of Animal Bite Treatment Centers (ABTCs) has improved accessibility; however, the resulting upsurge in PEP demand is not sustainable, and human rabies deaths continue. Dog vaccination coverage also remains inadequate, and it is unclear whether surveillance is effective. Methods: Here, we used Integrated Bite Case Management (IBCM) to collect enhanced rabies surveillance data in Oriental Mindoro Province over a 3-year period (2020-2022). Adapting a probabilistic decision tree model, we estimated the burden of rabies, evaluated surveillance performance, and analyzed the costs and benefits of current rabies prevention and control practices in the province. Results: The incidence of bite patients receiving PEP was high in Oriental Mindoro Province (1,246/100,000 persons/year), though < 3% of presenting patients were deemed high-risk for rabies exposure (24/100,000 persons/year). Using a decision tree model, we estimated that around 73.8% of probable rabies-exposed patients sought PEP (95% Prediction Interval, PrI: 59.4%-81.1%) and that routine surveillance confirmed < 2% of circulating animal rabies cases, whereas IBCM resulted in a nearly fourfold increase in case detection. Furthermore, we estimated that an average of 560 (95% PrI 217-1,090) dogs may develop rabies annually in the province, equating to 3-5 cases per 1,000 dogs per year. On average, 20 to 43 human deaths were averted by PEP each year in Oriental Mindoro at an annual cost of $582,110 USD (i.e., $51.44 USD per person) or $20,190 USD (95% PrI $11,565-79,400) per death averted. Conclusion: While current practices for PEP provisioning in the Philippines have improved access, a large proportion of people exposed to rabies (> 26%, 95% PrI 18.8%-40.1%) are still not seeking healthcare. Integrating an intersectoral surveillance system, such as IBCM, into national policy could greatly improve case detection if well implemented, with further benefits extending to guidance for PEP administration, potentially reducing unnecessary expenditure on PEP, and situational awareness to inform control of rabies through mass dog vaccination.

Rapid in-country sequencing of whole virus genomes to inform rabies elimination programmes.

Genomic surveillance is an important aspect of contemporary disease management but has yet to be used routinely to monitor endemic disease transmission and control in low- and middle-income countries. Rabies is an almost invariably fatal viral disease that causes a large public health and economic burden in Asia and Africa, despite being entirely vaccine preventable. With policy efforts now directed towards achieving a global goal of zero dog-mediated human rabies deaths by 2030, establishing effective surveillance tools is critical. Genomic data can provide important and unique insights into rabies spread and persistence that can direct control efforts. However, capacity for genomic research in low- and middle-income countries is held back by limited laboratory infrastructure, cost, supply chains and other logistical challenges. Here we present and validate an end-to-end workflow to facilitate affordable whole genome sequencing for rabies surveillance utilising nanopore technology. We used this workflow in Kenya, Tanzania and the Philippines to generate rabies virus genomes in two to three days, reducing costs to approximately £60 per genome. This is over half the cost of metagenomic sequencing previously conducted for Tanzanian samples, which involved exporting samples to the UK and a three- to six-month lag time. Ongoing optimization of workflows are likely to reduce these costs further. We also present tools to support routine whole genome sequencing and interpretation for genomic surveillance. Moreover, combined with training workshops to empower scientists in-country, we show that local sequencing capacity can be readily established and sustainable, negating the common misperception that cutting-edge genomic research can only be conducted in high resource laboratories. More generally, we argue that the capacity to harness genomic data is a game-changer for endemic disease surveillance and should precipitate a new wave of researchers from low- and middle-income countries.

Risk assessment of Ebola Reston virus in humans in the Philippines.

OBJECTIVE: There have been five documented outbreaks of Ebola Reston virus (RESTV) in animals epidemiologically linked to the Philippines. This assessment was conducted to determine the risk of RESTV occurring in humans in the Philippines and its potential pathogenicity in humans. METHODS: The World Health Organization Rapid Risk Assessment of Acute Public Health Events Manual was used for the assessment. A literature review was done and a risk assessment matrix was used for the risk characterization of the outbreaks in the Philippines. The risk assessment was conducted by the Philippines Field Epidemiology Training Program. RESULTS: The risk of RESTV occurring in humans in the Philippines and its potential pathogenicity in humans were both assessed as moderate. Animals involved in RESTV outbreaks in the Philippines were non-human primates and domestic pigs. The presence of RESTV in pigs poses a possibility of genetic evolution of the virus. Although RESTV has been identified in humans, there was no death or illness attributed to the infection. The Philippines Inter-agency Committee on Zoonoses oversees collaboration between the animal and human health sectors for the prevention and control of zoonoses. However, there is no surveillance of risk animals or previously affected farms to monitor and facilitate early identification of cases. DISCUSSION: The moderate risk of RESTV recurring among humans in the Philippines and its potential pathogenicity in humans reinforces the need for early detection, surveillance and continued studies of RESTV pathogenesis and its health consequences. The One Health approach, with the involvement and coordination of public health, veterinary services and the community, is essential in the detection, control and management of zoonosis.

Reemergence of Reston ebolavirus in Cynomolgus Monkeys, the Philippines, 2015.

In August 2015, a nonhuman primate facility south of Manila, the Philippines, noted unusual deaths of 6 cynomolgus monkeys (Macaca fascicularis), characterized by generalized rashes, inappetence, or sudden death. We identified Reston ebolavirus (RESTV) infection in monkeys by using serologic and molecular assays. We isolated viruses in tissues from infected monkeys and determined viral genome sequences. RESTV found in the 2015 outbreak is genetically closer to 1 of the 4 RESTVs that caused the 2008 outbreak among swine. Eight macaques, including 2 also infected with RESTV, tested positive for measles. Concurrently, the measles virus was circulating throughout the Philippines, indicating that the infection of the macaques may be a reverse zoonosis. Improved biosecurity measures will minimize the public health risk, as well as limit the introduction of disease and vectors.

Protecting children from rabies with education and pre-exposure prophylaxis: A school-based campaign in El Nido, Palawan, Philippines.

BACKGROUND: Rabies remains endemic in the Philippines. A study was conducted in El Nido, Palawan, Philippines to: (i) detect the true incidence of animal bites in school children aged 5-14 years using active surveillance and compare these data to estimates from the existing passive surveillance system, (ii) evaluate the impact of rabies prevention education and pre-exposure prophylaxis (PrEP) on animal bite incidence, and (iii) assess the health economic impact of the interventions. METHODOLOGY AND PRINCIPAL FINDINGS: A cohort of 4,700 school children was followed-up for any suspect rabies exposures between January 2011 and December 2012. Data on animal bite incidence from the study cohort were compared to that obtained from a review of consultation records at the Animal Bite Treatment Center (ABTC). PrEP was offered to children in all 27 public elementary schools in El Nido (in January to February 2012). Teachers were given a manual for integrating rabies in the public elementary school curriculum during the school year 2012-13. Active surveillance of the cohort revealed a higher incidence of suspect rabies exposures than that from passive surveillance. Despite a decrease in the number of Category III bites, there was no significant decrease in overall bite incidence as a result of the interventions. However, there was an increase in rabies awareness among school children in all grade levels. There was also a high level of acceptability of PrEP. Children who received PrEP and subsequently were bitten only needed two booster doses for post-exposure prophylaxis, resulting in substantial cost-savings. CONCLUSIONS/SIGNIFICANCE: The true burden of animal bites remains underestimated in ABTC records. PrEP is advantageous in selected population groups, i.e. school-aged children in rabies endemic areas with limited access to animal and human rabies prevention services. Educating school children is beneficial. Strengthening veterinary interventions to target the disease at source is important.

Willingness to Pay for Dog Rabies Vaccine and Registration in Ilocos Norte, Philippines (2012).

BACKGROUND: The Philippines is one of the developing countries highly affected by rabies. Dog vaccination campaigns implemented through collaborative effort between the government and NGOs have played an important role in successfully reducing the burden of disease within the country. Nevertheless, rabies vaccination of the domestic animal population requires continuous commitment not only from governments and NGOs, but also from local communities that are directly affected by such efforts. To create such long-term sustained programs, the introduction of affordable dog vaccination and registration fees is essential and has been shown to be an important strategy in Bohol, Philippines. The aim of this study, therefore, was to estimate the average amount of money that individuals were willing to pay for dog vaccination and registration in Ilocos Norte, Philippines. This study also investigated some of the determinants of individuals' willingness to pay (WTP). METHODS: A cross-sectional questionnaire was administered to 300 households in 17 municipalities (out of a total of 21) selected through a multi-stage cluster survey technique. At the time of the survey, Ilocos Norte had a population of approximately 568,017 and was predominantly rural. The Contingent Valuation Method was used to elicit WTP for dog rabies vaccination and registration. A 'bidding game' elicitation strategy that aims to find the maximum amount of money individuals were willing to pay was also employed. Data were collected using paper-based questionnaires. Linear regression was used to examine factors influencing participants' WTP for dog rabies vaccination and registration. KEY RESULTS: On average, Ilocos Norte residents were willing to pay 69.65 Philippine Pesos (PHP) (equivalent to 1.67 USD in 2012) for dog vaccination and 29.13PHP (0.70 USD) for dog registration. Eighty-six per cent of respondents were willing to pay the stated amount to vaccinate each of their dogs, annually. This study also found that WTP was influenced by demographic and knowledge factors. Among these, we found that age, income, participants' willingness to commit to pay each year, municipality of residency, knowledge of the signs of rabies in dogs, and number of dogs owed significantly predicted WTP.

Estimating the global burden of endemic canine rabies.

BACKGROUND: Rabies is a notoriously underreported and neglected disease of low-income countries. This study aims to estimate the public health and economic burden of rabies circulating in domestic dog populations, globally and on a country-by-country basis, allowing an objective assessment of how much this preventable disease costs endemic countries. METHODOLOGY/PRINCIPAL FINDINGS: We established relationships between rabies mortality and rabies prevention and control measures, which we incorporated into a model framework. We used data derived from extensive literature searches and questionnaires on disease incidence, control interventions and preventative measures within this framework to estimate the disease burden. The burden of rabies impacts on public health sector budgets, local communities and livestock economies, with the highest risk of rabies in the poorest regions of the world. This study estimates that globally canine rabies causes approximately 59,000 (95% Confidence Intervals: 25-159,000) human deaths, over 3.7 million (95% CIs: 1.6-10.4 million) disability-adjusted life years (DALYs) and 8.6 billion USD (95% CIs: 2.9-21.5 billion) economic losses annually. The largest component of the economic burden is due to premature death (55%), followed by direct costs of post-exposure prophylaxis (PEP, 20%) and lost income whilst seeking PEP (15.5%), with only limited costs to the veterinary sector due to dog vaccination (1.5%), and additional costs to communities from livestock losses (6%). CONCLUSIONS/SIGNIFICANCE: This study demonstrates that investment in dog vaccination, the single most effective way of reducing the disease burden, has been inadequate and that the availability and affordability of PEP needs improving. Collaborative investments by medical and veterinary sectors could dramatically reduce the current large, and unnecessary, burden of rabies on affected communities. Improved surveillance is needed to reduce uncertainty in burden estimates and to monitor the impacts of control efforts.

Genetic diversity and geographic distribution of genetically distinct rabies viruses in the Philippines.

BACKGROUND: Rabies continues to be a major public health problem in the Philippines, where 200-300 human cases were reported annually between 2001 and 2011. Understanding the phylogeography of rabies viruses is important for establishing a more effective and feasible control strategy. METHODS: We performed a molecular analysis of rabies viruses in the Philippines using rabied animal brain samples. The samples were collected from 11 of 17 regions, which covered three island groups (Luzon, Visayas, and Mindanao). Partial nucleoprotein (N) gene sequencing was performed on 57 samples and complete glycoprotein (G) gene sequencing was performed on 235 samples collected between 2004 and 2010. RESULTS: The Philippine strains of rabies viruses were included in a distinct phylogenetic cluster, previously named Asian 2b, which appeared to have diverged from the Chinese strain named Asian 2a. The Philippine strains were further divided into three major clades, which were found exclusively in different island groups: clades L, V, and M in Luzon, Visayas, and Mindanao, respectively. Clade L was subdivided into nine subclades (L1-L9) and clade V was subdivided into two subclades (V1 and V2). With a few exceptions, most strains in each subclade were distributed in specific geographic areas. There were also four strains that were divided into two genogroups but were not classified into any of the three major clades, and all four strains were found in the island group of Luzon. CONCLUSION: We detected three major clades and two distinct genogroups of rabies viruses in the Philippines. Our data suggest that viruses of each clade and subclade evolved independently in each area without frequent introduction into other areas. An important implication of these data is that geographically targeted dog vaccination using the island group approach may effectively control rabies in the Philippines.

Surveillance guidelines for disease elimination: a case study of canine rabies.

Surveillance is a critical component of disease control programmes but is often poorly resourced, particularly in developing countries lacking good infrastructure and especially for zoonoses which require combined veterinary and medical capacity and collaboration. Here we examine how successful control, and ultimately disease elimination, depends on effective surveillance. We estimated that detection probabilities of <0.1 are broadly typical of rabies surveillance in endemic countries and areas without a history of rabies. Using outbreak simulation techniques we investigated how the probability of detection affects outbreak spread, and outcomes of response strategies such as time to control an outbreak, probability of elimination, and the certainty of declaring freedom from disease. Assuming realistically poor surveillance (probability of detection <0.1), we show that proactive mass dog vaccination is much more effective at controlling rabies and no more costly than campaigns that vaccinate in response to case detection. Control through proactive vaccination followed by 2 years of continuous monitoring and vaccination should be sufficient to guarantee elimination from an isolated area not subject to repeat introductions. We recommend that rabies control programmes ought to be able to maintain surveillance levels that detect at least 5% (and ideally 10%) of all cases to improve their prospects of eliminating rabies, and this can be achieved through greater intersectoral collaboration. Our approach illustrates how surveillance is critical for the control and elimination of diseases such as canine rabies and can provide minimum surveillance requirements and technical guidance for elimination programmes under a broad-range of circumstances.

Implementation of an intersectoral program to eliminate human and canine rabies: the Bohol Rabies Prevention and Elimination Project.

BACKGROUND: The province of Bohol, located in the Visayas islands region in the Philippines has a human population of 1.13 million and was the 4th highest region for human rabies deaths in the country, averaging 10 per year, prior to the initiation of the Bohol Rabies Prevention and Elimination Project (BRPEP). AIMS: The BRPEP was initiated in 2007 with the goal of building a sustainable program that would prevent human rabies by eliminating rabies at its source, in dogs, by 2010. This goal was in line with the Philippine National Rabies Program whose objective is to eliminate rabies by 2020. METHODS: The intersectoral BRPEP was launched in 2007 and integrated the expertise and resources from the sectors of agriculture, public health and safety, education, environment, legal affairs, interior and local government. The program included: increasing local community involvement; implementing dog population control; conducting mass dog vaccination; improving dog bite management; instituting veterinary quarantine; and improving diagnostic capability, surveillance and monitoring. Funding was secured from the national government, provincial, municipal and village units, dog owners, NGOs, the regional office of the WHO, the UBS Optimus Foundation, and the Global Alliance for Rabies Control. The BRPEP was managed by the Bohol Rabies Prevention and Eradication Council (BRPEC) under the jurisdiction of the Governor of Bohol. Parallel organizations were created at the municipal level and village level. Community volunteers facilitated the institution of the program. Dog population surveys were conducted to plan for sufficient resources to vaccinate the required 70% of the dogs living in the province. Two island-wide mass vaccination campaigns were conducted followed by "catch up" vaccination campaigns. Registration of dogs was implemented including a small fee that was rolled back into the program to maintain sustainability. Children were educated by introducing rabies prevention modules into all elementary schools in Bohol. Existing public health legislation at the national, provincial, and municipal level strengthened the enforcement of activities. A Knowledge, Attitude and Practices (KAP) survey was conducted in 2009 to evaluate the educational knowledge of the population. Increased surveillance was instituted to ensure that dogs traveling into and out of the province were vaccinated against rabies. Human and animal cases of rabies were reported to provincial and national authorities. KEY RESULTS: Within the first 18 months of the BRPEP, human rabies deaths had decreased annually from 0.77 to 0.37 to zero per 100,000 population from 2007-2009. Between October 2008 and November 2010 no human and animal cases were detected. Increased surveillance on the island detected one suspected human rabies case in November 2010 and one confirmed case of canine rabies in April 2011. Two mass vaccination campaigns conducted in 2007 and 2008 successfully registered and vaccinated 44% and 70% of the dogs on the island. The additional surveillance activities enabled a mobilization of mop up vaccination activities in the region where the human and canine case was located. Due to the increased effective and continuous surveillance activities, rabies was stopped before it could spread to other areas on the island. The program costs totaled USD 450,000. Registration fees collected to maintain the program amounted to USD 105,740 and were re-allocated back into the community to sustain the program.

Reston ebolavirus in humans and animals in the Philippines: a review.

The 2008 Reston ebolavirus infection event in domestic pigs has triggered continuing epidemiologic investigations among Philippine health and veterinary agencies in collaboration with international filovirus experts. Prior to this, there were only 3 known and documented Reston ebolavirus outbreaks in nonhuman primates in the world, all traced back to a single geographic source in the Philippines in a monkey breeding/export facility. The first one in 1989 was the first-ever Ebola virus that emerged outside of Africa and was also the first known natural infection of Ebola virus in nonhuman primates. When it was first discovered among laboratory monkeys in the United States, the source was immediately traced back to the farm located in the Philippines. The second outbreak was in 1992-93. The third episode in 1996 was the last known outbreak before Reston ebolavirus reemerged in pigs in 2008. The isolated outbreaks involving 2 animal species bring forth issues requiring further investigations, and highlight the significance of intersectoral collaboration to effectively address zoonoses prevention and control/response in the interest of minimizing public health risk.

Renewed global partnerships and redesigned roadmaps for rabies prevention and control.

Canine rabies, responsible for most human rabies deaths, is a serious global public health concern. This zoonosis is entirely preventable, but by focusing solely upon rabies prevention in humans, this "incurable wound" persists at high costs. Although preventing human deaths through canine rabies elimination is feasible, dog rabies control is often neglected, because dogs are not considered typical economic commodities by the animal health sector. Here, we demonstrate that the responsibility of managing rabies falls upon multiple sectors, that a truly integrated approach is the key to rabies elimination, and that considerable progress has been made to this effect. Achievements include the construction of global rabies networks and organizational partnerships; development of road maps, operational toolkits, and a blueprint for rabies prevention and control; and opportunities for scaling up and replication of successful programs. Progress must continue towards overcoming the remaining challenges preventing the ultimate goal of rabies elimination.

Rapid detection of rabies virus by reverse transcription loop-mediated isothermal amplification.

In this study, reverse transcription loop-mediated isothermal amplification (RT-LAMP) was established which can detect 10(3) copies of viral RNA corresponding to approximately 5 fg of RNA. RT-LAMP with the Phil primer set designed according to the nucleotide sequences obtained from a Kyoto patient who contracted rabies in the Philippines was able to amplify all 16 street viral sequences derived from the Philippines. The specificity of RT-LAMP products was easily confirmed by digestion with RsaI restriction enzyme. The reaction of RT-LAMP could be completed within 1 h and could be conducted under isothermal conditions using a conventional water bath or heat blocks, indicating that RT-LAMP is ideal for the diagnosis of rabies in developing countries. Although further study is required to establish more universal RT-LAMP primers applicable to viruses from other regions or countries, the fast, easy, simple, sensitive and specific RT-LAMP method established here might be useful for rabies diagnosis and can facilitate studies of rabies epidemiology where rabies is enzootic, particularly in developing countries.

The origin and phylogeography of dog rabies virus.

Rabies is a progressively fatal and incurable viral encephalitis caused by a lyssavirus infection. Almost all of the 55 000 annual rabies deaths in humans result from infection with dog rabies viruses (RABV). Despite the importance of rabies for human health, little is known about the spread of RABV in dog populations, and patterns of biodiversity have only been studied in limited geographical space. To address these questions on a global scale, we sequenced 62 new isolates and performed an extensive comparative analysis of RABV gene sequence data, representing 192 isolates sampled from 55 countries. From this, we identified six clades of RABV in non-flying mammals, each of which has a distinct geographical distribution, most likely reflecting major physical barriers to gene flow. Indeed, a detailed analysis of phylogeographic structure revealed only limited viral movement among geographical localities. Using Bayesian coalescent methods we also reveal that the sampled lineages of canid RABV derive from a common ancestor that originated within the past 1500 years. Additionally, we found no evidence for either positive selection or widespread population bottlenecks during the global expansion of canid RABV. Overall, our study reveals that the stochastic processes of genetic drift and population subdivision are the most important factors shaping the global phylogeography of canid RABV.

Case report: rapid ante-mortem diagnosis of a human case of rabies imported into the UK from the Philippines.

The United Kingdom is free from rabies, with the last human death from indigenous rabies recorded in 1902. However, between 1946 and 2000, 20 deaths were reported in the United Kingdom in people who were bitten and infected while abroad in rabies endemic areas. The rapid diagnosis of suspected human rabies cases influences the use of anti-rabies post-exposure prophylaxis for potential contacts with the victim. In addition, the occurrence of a human rabies case requires urgent investigation to support patient management policies. In May 2001, a case of human rabies imported into the United Kingdom from the Philippines was identified. A 55-year-old man was admitted to University College Hospital, London, with clinical symptoms and a history consistent with exposure to rabies. Saliva, cerebrospinal fluid), and skin biopsies (from the wound site and nape of the neck) were submitted for conventional ante-mortem diagnostic techniques. Established diagnostic techniques, including the fluorescent antibody test (FAT), mouse inoculation test, (MIT) and the rabies tissue culture inoculation test (RTCIT), failed to detect the virus. In contrast, hemi-nested reverse transcription-polymerase chain reaction (RT-PCR), followed by automated sequencing confirmed the presence of classical rabies virus (genotype 1) in both the saliva and skin specimens within 36 hr of sample submission. Subsequent phylogenetic analysis demonstrated that this isolate was closely related to that of canine variants currently circulating in the Philippines.

Histopathology of natural Ebola virus subtype Reston infection in cynomolgus macaques during the Philippine outbreak in 1996.

We investigated the livers, spleens, kidneys and lungs collected from 24 cynomolgus macaques (Macaca fascicularis) naturally infected with Ebola virus subtype Reston (EBO-R) during the Philippine outbreak in 1996, in order to reveal the histopathologic findings. These macaques showed necrotic hepatocytes with inclusions, slight to massive fibrin deposition in splenic cords, depletion of lymphoid cells in the white pulp of the spleen, and fibrin thrombi in some organs. Immunohistochemical analysis using anti-leukocyte antigen L1 antibody revealed an increase in blood-derived macrophages/monocytes in the livers, kidneys and lungs of EBO-R infected macaques. EBO-R NP antigens were detected in the macrophages/monocytes, endothelial cells and fibroblasts in the liver, spleen, kidney and lung. These results indicate that EBO-R infection is characterized by systemic coagulopathy and an increase in blood-derived macrophages/monocytes in accordance with the EBO-R propagation in macrophages/monocytes.

Chronological and spatial analysis of the 1996 Ebola Reston virus outbreak in a monkey breeding facility in the Philippines.

To describe the transmission pattern of natural infection with Ebola Reston (EBO-R) virus in a breeding colony, the chronological and spatial analysis of mortality during the 1996 EBO-R virus outbreak was done in this study. The EBO-R virus infection among monkeys in the facility was widespread. Over a period of 3 months, 14 out of 21 occupied units were contaminated with antigen positive animals. A large number of wild-caught monkeys were involved in this outbreak suggesting that wild-caught monkeys have a high susceptibility to EBO-R virus infection. In this outbreak, morbidity patterns for individual animal units were very different regardless of the type and size of cages, individual or gang cages. The results suggest that not only the cage size but also poor animal husbandry practices may be risk factors for the spread of EBO-R infection.