Integration of human rabies surveillance and preventive measures in the State of Ceará, Northeast Brazil

INTRODUCTION

Rabies is a neglected tropical disease with considerable impact, mainly on resource-poor and disadvantaged populations. The World Health Organization’s most recent roadmap “Ending the neglect to attain the Sustainable Development Goals: a road map for neglected tropical diseases 2021-2030” targets elimination of rabies as a public health problem, to be evidenced by 92% of the countries having achieved zero human deaths from rabies by 2030^[1].To achieve the elimination of rabies as a public health problem worldwide, it is necessary to adapt strategies at regional and national levels, to increase financial investment, and to apply measures according to specific local conditions^[2-4].

As a result of regional efforts and the ongoing support by the Pan American Health Organization, systematic rabies control measures were strengthened in Latin America since the 1980s, and canine cases were reduced by 98%^[4,5]. Human rabies still persists on the continent, and some areas register canine rabies. On the other hand, in some other areas there is an increasing importance of sylvatic animals for transmission, such as hematophagous bats^[4,6,7].

Rabies control programs usually have focused on vaccination of dogs and cats as main transmitters, and often did not fully consider interdisciplinary approaches including humans, domestic animals, sylvatic animals, and the environment. While classically rabies control measures include vaccination and awareness campaigns, One Health approach integrates all major stakeholder groups and integrates more comprehensive activities. Thus, some authors have called for a One Health approach to further improve effectiveness of rabies control and prevention measures^[8].

In Brazil, animal rabies surveillance and control measures are coordinated by the Ministry of Health and the Ministry of Agriculture and Livestock, in an integrated way, consisting of disease surveillance in dogs and cats, cattle, horses and wild species such as bats. There are still human rabies cases in the country; from 2010 to 2020, there was a total of 39 registered cases (all confirmed by laboratory diagnosis), with about half of them transmitted by bats, only around a quarter by dogs, 10% by cats, and another 10% by non-human primates^[9]. Nowadays, hematophagous bats (Desmodus rotundus) and marmosets (Callithrix jacchus) are considered the main aggressor species for rabies virus transmission to humans in Brazil^[10,11].

Ceará State in Northeast Brazil consists of 184 municipalities [Figure 1]. The population size is approximately 9 million, in an area of 149,000 km². The state is mainly characterized by savannah/caatinga vegetation, with exception of some Atlantic rain forest remains. The integrated program for rabies control was implemented in Ceará State in 2008. Since then, both the State Health Secretariat and the State Livestock Authority (ADAGRI) have put a strong emphasis on interdisciplinary and transdisciplinary aspects to improve rabies surveillance and control for humans, domestic animals, and wildlife. There is a multidisciplinary state rapid response team composed of about 10 professionals, including veterinarians, nurses, pharmacists, community health agents, endemic control agents, and health educators, who immediately visit the affected community and perform field investigations after the notification of a case. They remain in the field until the risk situation is controlled. The measures performed during these field missions include case investigation, contact tracing and post-exposure prophylaxis for exposed people, vaccination of people at risk, information and education campaigns, seminars for health professionals, vaccination of domestic and farm animals/livestock, laboratory analysis of suspected domestic and wild animals, viral strain identification, and collection of wild animals kept as pets in the communities.

Figure 1. Location of Ceará State in Northeast Brazil, highlighting the municipalities where the rabies cases occurred, 2004-2021.

As a way of implementing rabies surveillance and control in the state, several training activities were developed, such as courses, workshops, seminars, research studies, and institutional partnerships. The training activities of the integrated program for the control and surveillance of rabies in Brazil’s Ceará State are detailed in Table 1. The trainings were mainly carried out reactively, during the occurrence and investigation of human cases.

In this paper, we describe the practical aspects of the above-mentioned integrated approach.

METHODS

We describe in detail the history, case development, and surveillance and prevention measures of all cases of human rabies that occurred in the state in the period 2004-2021.

We analyzed charts of the patients admitted to the state reference hospital for infectious diseases in the state capital Fortaleza. Five rabies patients of this study were admitted to this hospital. One patient was not transportable and was admitted to the regional hospital in Barbalha municipality. In this case, the expert team from the reference hospital supported the regional hospital team in clinical management.

In addition, we reviewed technical reports of the State Health Secretariat, and provided information from personal notes, as two of the authors (Duarte NFH & de Oliveira Moreno J) participated as members of the team in the investigations, as well as prevention and surveillance measures.

In three cases, rabies was confirmed by RT-PCR ante-mortem by the Ceará State reference laboratory, and in all cases, diagnosis was confirmed post-mortem by direct immunofluorescence performed at the Pasteur Institute in São Paulo. Viral typing of samples was performed by the Pasteur Institute for all cases.

RESULTS

Six cases of human rabies were recorded in the state, in six different municipalities scattered around the state’s hinterland [Figure 1]. All cases occurred in rural areas, and affected people who came from isolated resource-poor communities. Figure 2 depicts the house of case #1 and the primary health care center in the community, which is exemplary of the low socio-economic conditions and the poor health care system in the affected communities.

Figure 2. (A) House of rabies case #1 in the rural area of São Luis do Curú municipality. (B) Primary Health Care Center of the community.

Demographic and disease-related characteristics of the individuals are presented in Table 2. Five of the six patients were males. In four cases, transmission occurred by marmosets (Callithrix jacchus), one by a hematophagous bat (Desmodus rotundus), and another by a domestic dog, though the identified viral strain was sylvatic. All patients were bitten by the rabid animals, mostly on the hand. In the three patients, where diagnosis was confirmed by RT-PCR ante-mortem in cerebrospinal fluid, hair follicle, and saliva, the Recife/Milwaukee treatment protocol was applied. All six patients died.

Table 3 describes the detailed history and development of cases, and the surveillance measures performed by the state’s rapid response team which started investigation immediately after notification. In all cases, the technical team of the State Health Secretariat collaborated intensively with the Municipal Health Secretariats, Regional Health Coordination, State Livestock Authority, Education Secretariat, and other authorities and organizations, for preparation of an action and control plan, surveillance, and viral analyses. The rapid response team performed comprehensive actions to prevent any additional cases, and to make the population aware of the rabies risk. A large number of wild animals (marmosets) kept as pets were collected in the communities.

The case descriptions show that people in the communities were not aware of the risk of rabies being transmitted by wild animals, and sometimes even approached the diseased animals actively (cases #1, #2, #4, and #5). One patient was attacked by a hematophagous bat while sleeping (case #6). He was living in a simple house, with easy access for bats to the sleeping room [Figure 3]. Domestic animals were abundant around the house of this case [Figure 4]. This is remarkable, as usually, these bats prefer blood-feeding on animals and only feed on humans in the absence of adequate animals.

Figure 3. (A) House of rabies case #6 in the rural area of Iracema municipality. (B) View from inside the house evidencing easy access of hematophagous bats to the sleeping room.

Figure 4. Domestic animals around the house of case #6 who was attacked by a hematophagous bat (Desmodus rotundus).

Only one patient presented at a primary health care center before the onset of symptoms (case #3). He presented to the primary health care center for wound care, after being bitten by his hunting dog, but did not receive any post-exposure prophylaxis due to logistic problems; no physician was present at the weekend and he did not return to the health center thereafter. Even after onset of symptoms, in all cases, the suspected diagnosis was not rabies at first.

DISCUSSION

Our detailed description of the investigation of all human rabies that occurred during a period of 18 years in Ceará State demonstrates the need for ongoing integrated surveillance and control measures. All cases occurred in resource-poor communities with limited access to the educational and health systems, in the rural hinterland. Rabies in the state can be characterized as a rural wildlife-mediated disease of the mostly underprivileged populations, being one of the most neglected diseases in the region. The affected communities were not aware about the risk of wildlife-mediated rabies, there was limited access to the health system hampering timely administration of post-exposure prophylaxis, and the primary health care system did not adequately consider rabies as a differential diagnosis. The multidisciplinary state rapid response teams realized integrated measures including all stakeholder groups to prevent further cases.

In all cases, wild rabies virus strains were isolated. In fact, canine rabies has virtually been eliminated from Brazil^[12]. Rabies used to be common in the state in domestic animals and in urban areas some decades ago, but due to intensive anti-rabies campaigns, transmission by dogs has been eliminated. In 2003, seven cases of human rabies were still registered, all of them transmitted by dogs. The last rabies case transmitted by a dog in the state occurred in 2010^[13]. Transmission by wild animals, mainly by marmosets and hematophagous bats, increased since then, indicating the importance of integrated and continuous measures, especially regarding information and education campaigns.

Before implementation of the integrated measures, the state health department carried out rabies control together with the municipal health departments when there were cases of animal or human rabies notified. Rabies surveillance in wild animals consisted of collecting biological samples of dead animals found on state highways, such as wild canids and raccoons, for laboratory diagnosis. Since 2008, with the occurrence of more and more human cases transmitted by wild animals, especially marmosets, the focus was widened to non-human primates (especially marmosets and capuchin monkeys) kept as pets, in collaboration with environmental authorities (IBAMA). Activities included collection of animals and information and education measures. Subsequently, visits were made to the homes for awareness-raising about environmental legislation, disease risk, and animal welfare. Since then, the rabies control program of the state has been working continuously on awareness raising about the risk of raising wild animals as pets, performed seminars and courses on sylvatic rabies and surveillance methods for health professionals. Consequently, there was a reduction of human cases in recent years.

Surveillance of domestic and wild animals (including bats, marmosets, foxes, and other animals) is important to reduce the transmission risk^[10]. Clearly, successful control and elimination of infectious diseases depend on effective disease surveillance, especially in the case of zoonoses, including rabies^[14]. However, surveillance often is not given priority, due to other issues that seem to be more urgent in resource-poor settings^[15]. Interdisciplinary surveillance would include surveillance of rabies virus in bats, in collaboration of health and agricultural authorities^[10]. We have discussed recently the importance of passive surveillance of rabies virus in bats and marmosets being fundamental for rabies control in both humans and domestic animals in Brazil’s Ceará State^[10].

Our study points out several bottlenecks in the implementation of the rabies control program, mainly regarding access to the health system, awareness of health professionals, and knowledge of the population on rabies transmission. Rabies symptoms and signs are often non-specific, and the disease is rare, which may explain the delayed diagnosis of the reported cases. Rabies should always be suspected in patients with neurological disorders, and professionals should ask about any animal contacts. Intensified and continuous professional education (health professionals, veterinarians, and primary health care agents) and information and education campaigns (communities at risk and schoolteachers) are important.

One focus of training for health professionals should be the correct application of post-exposure prophylaxis. For surveillance, the Brazilian nationwide health information system for notifiable diseases (called SINAN) registers patients seeking post-exposure prophylaxis. A nationwide study has shown that less than half of these received complete post-exposure prophylaxis according to Brazil’s Ministry of Health guidelines, and consequently better management of animal bites has been suggested^[12]. Another nationwide study based on passive surveillance data has shown that in Brazil, only half of patients received the correct post-exposure prophylaxis^[16]. A recent study from Ceará State identified 231,694 incidents involving animals. Of this total, 222,036 (95.8%) received no or incomplete post-exposure prophylaxis, as compared to the Ministry of Health’s prophylactic anti-rabies treatment guidelines^[17]. Similarly, post-exposure prophylaxis in Haiti was very low, where only 31% of rabies exposed individuals had initiated post-exposure prophylaxis^[15]. To achieve zero human deaths from rabies, universal access and availability of adequate post-exposure prophylaxis for all potential exposures will be needed.

The keeping of wild animals is prohibited by law in Brazil, but in collaboration with environmental authorities, the rapid response team identified and collected a high number of marmosets being kept as domestic animals in the communities. Thus, a major focus in education campaigns should be given to the sylvatic animals that transmit rabies to humans. Elimination of rabies in sylvatic animals is feasible in some settings. Oral rabies vaccine-containing baits are deposited in natural habitats. For example, wildlife-mediated rabies has virtually been eliminated from western Europe, as a result of oral rabies vaccination campaigns for foxes and raccoon dogs^[18], and an additional control approach may consist of placing vaccine baits close to communities in rural areas, but laboratory and field research would be required to determine if such an approach would be effective and feasible in Ceará.

Control of neglected tropical diseases, and specifically rabies control within the One Health approach would include human health, social sciences, environmental, animal health, and wildlife sectors, embedded into a strong routine surveillance and reporting system^[8,19]. Integrated measures depend on the specific settings, and may consist of pre- and post-exposure prophylaxis, adequate diagnosis, capacity building, reducing wildlife and domestic animal interactions, vaccination of domestic animals, and active and passive surveillance. All major stakeholder groups should be included, and the communities may be actively involved in surveillance actions. The focus on specific areas, and most vulnerable populations ideally would also include other neglected tropical diseases endemic in Brazil^[20].

This multidisciplinary approach, as exemplified by the state rabies control program in Ceará, has been an important and successful step to improve surveillance and control actions. In Mexico, dog-mediated rabies has been eliminated, by implementing mass dog vaccination campaigns, effective surveillance, awareness-raising campaigns, and easy access to post-exposure prophylaxis^[21]. Other countries, mainly in Asia where traditionally most human rabies have occurred, also successfully implemented the One Health approach, and reduced canine rabies and human cases significantly, such as in India where stray dogs pose major problem for rabies control^[22], and in Nepal where its government adopted a nationwide One Health strategy for all relevant sectors, including zoonoses^[8]. In China, the One Health approach has been recommended to integrate different disciplines and the different levels of rabies control - control of human rabies including strengthening of public awareness in high-risk rural populations and control of rabies in wild animals, livestock, and stray dogs, including surveillance^[23]. Similarly, in Australia, which is free of canine rabies, One Health activities have been proposed to effectively prevent the reemergence of the disease^[24]. In Sri Lanka, the One Health approach has been advocated, but there are still some obstacles for integrated measures, such as missing standardization of the control program, and insufficient harmonization of different areas involved^[25]. While on the grassroots level, this is usually very effective, on the high rank political level, silo thinking may prevail, and interdisciplinary approaches are sometimes difficult to establish^[26].Clearly, implementation measures should be tailored to the given epidemiologic, biological, cultural, and socio-economic context.

We conclude that there is an ongoing need for integrated surveillance and control measures in the state, for information and education campaigns, and professional training, especially focusing on wildlife-mediated rabies. An integrated One Health approach - as exemplified by the presented rabies control program in Ceará - is critical for human rabies elimination.