Rabies seroprevalence of street dogs from São Paulo City, Brazil

Evolution of Rabies in South America and Inter-Species Dynamics (2009-2018)

Rabies is listed as one of the World Health Organisation's (WHO) Neglected Tropical Diseases Worldwide, with a significant impact in South America. This paper explores the dynamics of rabies cases in humans, pets (dogs and cats), livestock and wildlife (bats in particular) in South America during the period 2009-2018. The data used in this study were derived from the two main databases for rabies in South America: the OIE-WAHIS from the World Organisation for Animal Health (OIE) and PANAFTOSA's Regional Information System for the Epidemiological Surveillance of Rabies (SIRVERA). Being a neglected disease with possible underreporting in some areas, the reported rabies cases may not always represent the real disease burden. The analysis focuses on the evolution of the number of cases in time and their spatial distribution, as well as on the main source of infections in humans, determined by laboratory assays of the antigenic variant or through epidemiological investigations. Additionally, Generalised Linear Mixed Models (GLMM) were used to evaluate the risk factors associated with the occurrence of human cases. Our results show that the highest impact of the disease in terms of number of cases was reported on livestock, while the overall number of cases (in animals and humans) progressively decreased along the study period. The spatial distribution of rabies in livestock showed two main clusters in the north-western (mainly Colombia) and in the south-eastern part of the affected area (Brazil), and a third smaller cluster in Peru. A cluster in dogs was observed in Bolivia. Out of the 192 human cases reported during the study period, 70% of them were transmitted by bats. The number of human cases reported during the study period were significantly associated with the number of rabies cases reported in livestock, pets and wildlife. Despite the overall decreasing case report rate, the disease still represents a major animal and public health concern in South America, and new strategies for compiling systematic information, networking and education are needed, as well as the education and training of veterinary staff.

The use of immunocontraception to improve rabies eradication in urban dog populations

ContextRabies causes ~55 000 human deaths each year, primarily as a result of bites from dogs, which are the major rabies reservoir in the developing world. Current rabies control strategies include vaccination, culling and surgical sterilisation of dogs. However, recently developed immunocontraceptives could be used alongside vaccination to apply fertility control to more animals. AimsWe used a modelling approach to explore (1) whether adding single-dose contraceptives to rabies vaccination would improve effectiveness of rabies eradication, (2) how sensitive control methods are to variation in population parameters and (3) the effects of applying control continuously or in pulses on rabies eradication. MethodsA continuous time, compartmental model was created to describe canine rabies epidemiology. Parameters were derived from the literature. The following three control methods were applied at varying rates and durations: vaccination, vaccination plus fertility control (v + fc) and culling. Outcomes were classified into the following three categories: rabies persistence, rabies eradication and population extinction. Key resultsWhen control was applied continuously for up to 24 months, vaccination was least effective; the effort required to eradicate rabies was about twice that required with culling or v + fc. At realistic control rates, only v + fc consistently resulted in rabies eradication. Increasing population growth rate and city size made rabies eradication harder; for vaccination, considerably greater control rates and durations were required, whereas culling and v + fc showed only minor decreases in effectiveness. When control was applied for 1 or 2 months (for one month every 12 months or every 6 months) per year for up to 20 years, vaccination became less effective because of population turnover between control periods; v + fc lost little effectiveness, as decreased birth rates reduced the input of susceptible animals. ConclusionsUsing immunocontraception alongside vaccination could improve rabies control campaigns by reducing the proportion of the population that must be treated, or reducing the necessary duration of the campaign. It could also make control effective under larger population growths, in larger cities and when control is pulsed. ImplicationsImmunocontraceptives could become a useful tool in canine rabies control by allowing fertility control to be applied on a large scale. Further work is required to improve understanding of dog ecology and parameterise location-specific models, which could be used to inform management plans.

Uso de sistemas de informação geográfica em campanhas de vacinação contra a raiva

OBJETIVO: Desenvolver método para planejamento e avaliação de campanhas de vacinação contra a raiva animal. MÉTODOS: O desenvolvimento da metodologia baseou-se em sistemas de informação geográfica para estimar a população e a densidade animal (canina e felina) por setores censitários e subprefeituras do município de São Paulo, em 2002. O número de postos de vacinação foi estimado para atingir uma dada cobertura vacinal. Foram utilizadas uma base de dados censitários para a população humana, e estimativas para razões cão:habitante e gato:habitante. RESULTADOS: Os números estimados foram de 1.490.500 cães e 226.954 gatos em São Paulo, uma densidade populacional de 1.138,14 animais domiciliados por km². Foram vacinados, na campanha de 2002, 926.462 animais, garantindo uma cobertura vacinal de 54%. O número total estimado de postos no município para atingir uma cobertura vacinal de 70%, vacinando em média 700 animais por posto foi de 1.729. Estas estimativas foram apresentadas em mapas de densidade animal, segundo setores censitários e subprefeituras. CONCLUSÕES: A metodologia desenvolvida pode ser aplicada de forma sistemática no planejamento e no acompanhamento das campanhas de vacinação contra a raiva, permitindo que sejam identificadas áreas de cobertura vacinal crítica.