Rabies in Trinidad

The Caribbean island of Trinidad lies just off the northeast coast of Venezuela, and has a deep rooted history of rabies. Canine transmitted rabies was eradicated from the island in the early 20th century with the last reported animal case occurring in 1914. However, in 1931 paralytic rabies transmitted by a bat vector was first scientifically recognized on the island, by local researchers Dr. Joseph L. Pawan and Captain H.V. Metivier. This newly recognized form of rabies was said to have been spread by the bite of the hematophagous bat (Desmodus routundus), when it fed on animal hosts. Recent molecular evidence has confirmed that this species is indeed associated with rabies variants found on the island. Interestingly, Tobago, the sister island of Trinidad, remains, to date, both vampire-free and paralytic rabies-free. Trinidadian folklore describes a character, akin to the vampire bat, called the "Soucouyant" that flies at night in search of human blood, and Carnival costumes depict bats so vividly that the species can often be elucidated.

The first and probably largest bat transmitted human rabies outbreak occurred in Trinidad from 1929 to 1937, with records of 89 humans succumbing to the disease with 73 confirmed cases. Since then, sporadic outbreaks of paralytic rabies have occurred in livestock, predominantly bovines, and the disease still holds an aura of mystery and awe. To date, both the Agriculture and Health Ministries are involved in the case investigation procedure to ascertain risk of transmission to humans from animals. This multi-agency approach has been in place since the 1930s and effectively illustrates the "One Health Concept".

During the first recognized outbreak, a prophylactic animal vaccination strategy was adopted, that focused on the local bovine population. Currently, the government veterinary services routinely execute an annual vaccination program in which all healthy cattle, bison and donkeys of a minimum age are immunized against rabies by primary inoculation and routine boosters with an inactivated virus formulation. It is presently legislated, under the Paralytic Rabies Regulations (1956) of Trinidad and Tobago that during the annual program, unvaccinated animals and animals due for booster vaccinations must be presented to the inspector for vaccination. Failure to do so is considered an offense and the farmer is liable to a penalty fee.

A vampire bat control program is also implemented by the Anti-Rabies Unit (ARU) of the Local Agriculture Ministry, but was conceptualized under the Department of Health. The ARU conducts island-wide bat roost surveillance and subsequently traps the vampire bats for the administration of a vampiricide (chemical control) and submission of specimens for rabies testing. The unit also investigates bat biting complaints in both animals and humans, assists with rabies vaccination and facilitates public education about rabies.

In 2010, World Rabies Day (WRD) was commemorated for the first time in Trinidad with a WRD Exhibition. This inaugural event honoured the day by displaying posters, videos and specimens related to the disease and the bat vector, together with the distribution of educational material. The event was
attended by farmers, public health officials, medical officers, animal health personnel, representatives of international agencies and tertiary level students. The momentum was continued in 2011 with the hosting of a Rabies Awareness Seminar, held in the county of St. Patrick where, the first human rabies case was recognized and the disease still has a notable presence. The target audience was mainly local farmers, who are the first point of contact with diseased animals and with whom lays the responsibility for reporting animal suspects to the Local Veterinary Authority. They were thus advised on the local history of rabies, disease etiology, transmission and clinical signs, public health risks, prevention and control measures including the importance of animal vaccination and the legislated requirements for such vaccination.

Over the years, rabies public educational initiatives have served well to supplement the control and prevention of the disease by vector control and vaccination measures. Such initiatives have been linked to reductions in rabies cases, as well as increased reporting of suspect animals. The overall effect has been a reduction in the risk of disease transmission to both animals and humans. World Rabies Day initiatives prove to be opportune events to refresh the knowledge of the population on both the tragic and triumphant history of the disease on the island and celebrate over 70 years without a human rabies case on the island.

Contributed by Dr. Janine Seetahal [DVM, MPH]. Janine is currently working as a Veterinary Officer at the Veterinary Diagnostic Laboratory, Ministry of Food Production, Land and Marine Affairs, Trinidad and Tobago.