An investigation into the prevalence of dog bites to primary school children in Trinidad

Trinidad and Tobago is a two Island Nation situated 11.00°N and 61.00°W. The population which consists of 1.5 million people comprises approximately 300,000 households [1]. There are no published reports on the size of the dog population or the number of pets per household. During the late 1990's, there was considerable press coverage on dog attacks mainly highlighting fatal or near fatal attacks by pit bull terriers and their crosses [2, 3]. This prompted the government to create a dangerous dogs act [4]aimed at banning certain breeds of dangerous dog and making owners liable if an animal has caused injury to persons. Trinidad and Tobago however, has no epidemiological data on the number of dog bites occurring per year and fatalities as a result of dog attacks are not recorded by the central statistical office.

The dog is known as man's best friend and it is estimated that over 52 million dogs cohabit with humans in the Unites States and the Center for Disease Control estimated that 799,700 out of 4.7 million bites occurring in 1994 required medical treatment [5]. The proportion of dog bites that are reported to authorities is variable with published estimates in the United States ranging from 10 – 50% [6]. Studies in developed countries have identified children under the age of 18 as the most frequent recipients of dog bites [6–8] with the ages that are most affected, varying among studies from, infants less than 1 year [9] to children aged 6 – 10 [10].

In addition to the severe physical trauma and potentially permanent disfiguring wounds sustained by a dog attack, dog bite victims are often burdened with emotional and psychological trauma [11]. Bites, no matter how severe, are a potential source of zoonotic infections particularly rabies and source of entry of pyogenic organisms and Clostridium tetani the cause of tetanus [12].

This study targets cases of dog bites using a questionnaire and informal interview to determine the potential magnitude of the dog bite risk to a vulnerable group in Trinidad. The survey records dog bites to children between the ages of 8–12 years attending primary schools in Trinidad to determine the risk factors associated with dog bites and to identify preventive strategies that could be implemented in order to reduce the incidence of injury to children from dog bites. This approach is intended to record factors associated with a bite incident through semi-structured interviews with children to record events which may otherwise go unreported. In addition, the semi-structured interview approach may prove valuable in empowering the target population to disclose information on associated risks factors which is often not ordinarily available to researchers and policy makers.

The study was conducted in accordance with the guidelines of the Helsinki Declaration. Data for this study was gathered using a questionnaire, and formal ethical approval from the university ethics committee was not sought as no research other than information gathering was carried out on human subjects. The questionnaire was reviewed by the authors, teachers and/or parents, school principals and students before proceeding. The aims and objectives of the study were explained and students were asked if they were willing to participate and verbal informed consent was given by teachers and/or parents, school principals and students. Some students declined participating in the study.

This survey recorded remembered bites over a 4-year period and although a bite was well defined to each respondent, it is expected that perceptual and recall problems were a source of bias. Young children were often not likely to remember details of the bite incident. The overall bite frequency should therefore be taken as an underestimate. The results also show that being bitten by a dog is a common occurrence in children within the 7 to10 year age group. Similar patterns were observed by Beck et al., [13] from a study in the USA where children belonging to the 7 to 12 age group were the most frequent victims of unreported bites.

Only 34.2% of victims who treated their wounds, used the services of a health care facility, and 25.0% of all victims did not apply basic first aid care to their wound. Those who were not treated by a doctor or at a primary care facility, preferred to seek treatment from a relative or friend. This may be due to several factors, including the victim, his or her parent or guardian, not perceiving the bite wound to be severe enough to seek professional assistance. No information was gathered as to the severity of the wound sustained or the length of time for healing. As dog bites are highly contaminated with several bacterial pathogens [12], bite wounds, regardless of severity, serve as a potential source of entry of anaerobic bacteria, particularly Clostridium tetani [12] and other bacteria such as Staphylococcus sp, Streptococcus sp, Pastuerella multocida and Capnocytophaga canimorsus [14]. It is therefore important that all children should receive prophylactic treatment for potential infections after a bite incident. Fortunately, the immunization system in Trinidad is well structured and most children have been immunized against tetanus by age 10 years. This factor may influence the apparent lackadaisical response to tending to bites received. Worldwide, carnivores, including the dog are important vectors for rabies, however in the Americas, bats are also major vectors[15]. Therefore, another factor which may influence attitudes toward seeking prompt medical care is the apparent absence of rabies in the canine population in Trinidad. The vampire bat as a vector for bovine rabies in Trinidad and a potential source of human rabies has been established since 1936 [16], however, the canine population is considered rabies-free. The public's knowledge of other potentially harmful zoonotic diseases from dog bites may therefore be quite limited.

This study showed that there was a significant association between the victims' gender and the likelihood of being bitten, with boys being 1.49 more times likely than girls to be bitten. Male victims predominated at ages 5 and 9 and above, however, female victims outnumbered males in the 6 to 8 age group. A review of data on dog bites in the United States showed that males were bitten significantly more often than females across all age groups [6]. A similar study in Canada from data taken from 16 hospitals indicated that 57.9% of all injuries related to dog bites were to males [17].

The severity of the sequelae to bite wounds was not assessed in this study, however the interviewer noted that many children were severely traumatized and some bite wounds received were highly disfiguring, to limbs and face. Two boys included in this study reported being bitten on their genitals and one boy who was not included in the study population had severely disfiguring injuries to his face which were received when he was bitten as an infant. Studies conducted elsewhere, have indicated that functional and aesthetic consequences are estimated to occur in 1 – 3% of all bites [12, 17–19]and child victims of dog bites should also be considered at risk of developing psychological injuries such as post traumatic stress disorder [11]. The vast majority of the biting dogs (86.5%) were owned animals and known to the victim. This is in agreement with other published data [6, 17, 20]. As there is no formal licensure for dogs in Trinidad, those classified as known have some sort of referral household which was recognized by the child. Unknown dogs were those which were not recognized by the child. Even though there is a very large stray dog population in Trinidad, dogs classified as unknown to the victim accounted for only 13% of bites, suggesting that unknown roaming dogs, though posing a risk of injury, are not the most significant source of dog bites to children in the country. It must be noted however, that it is very difficult to accurately classify dogs in Trinidad as many roaming animals have owners or some sort of referral household.

Most studies on dog injuries are derived from hospital data, often from emergency departments. In published reports of studies derived from hospital data [21–23], the most common site of injury by dog bites were to the face, head and neck, especially in children under 5 years. In our study, children under 8 years were not interviewed and we found that the lower leg, foot or toe were the most frequent site of bite wounds (39.3%) and bites to the face accounted for only 8.5% of all wounds. However, in a review of hospital records of animal bites in Thailand, bites to the upper extremities were more frequent in children under 6 years with the trend decreasing with increasing age, with attacks to the lower extremities becoming more common [24]. The relationship between the animal's head and the height of the victim are known indicators with respect to the site of injury, and young children therefore, are bitten more often on their face, head and upper extremities. It is also expected that severe dog bites and those sustained to the face are more likely to require medical attention as there is potential to result in permanent physical aesthetic damage to the child. To the contrary, in our study only 5 of the children who reported receiving bites to the head, face or neck sought professional medical care. It is also pertinent to mention that in our study, bites which most often received medical attention were those inflicted on the lower leg, foot or toe. The importance of considering the sources of data when comparing studies can therefore not be overemphasized.

A high proportion of children who were able to recall the month that they were bitten, indicated that the event occurred in either April or August. For the period 2000 – 2003, there were fewer bites occurring between September and December and except for 2000, between January and April. This trend may be explained in part by the fact that the month of April and the July/August period are the months when children are on vacation from school, often not well supervised and are more likely to have some sort of interaction with a biting dog which was known to them but not necessarily owned by them. These findings are in agreement with other studies which indicate that the peak incidence of bites occurred during the summer months or when children were not in school [17, 20, 24]. Many (33.0%) attacks in our study were unprovoked. Children, who were attacked without any prior interaction with the dog, reported either walking, running, or on their bike when attacked. Reports by others have also indicated that almost 30 – 50% of attacks to young children are unprovoked [17, 25]. Other victims, in this study, reported invading the dog's territory such as passing close to a dog or touching a dog with pups, feeding or disciplining a dog or parting fights. Close supervision of children when caring for dogs is therefore important in reducing risk of injury.

Our findings in this study have demonstrated that primary school children in Trinidad are bitten by dogs under very common circumstances but a frequency of 28% of dog bites in the 8–12 year age group is high enough to warrant the need for educating children and adults on responsible pet ownership. As 87% of those bitten were attacked by a dog known to them it is imperative that dog owners be aware of their responsibility in safe guarding the public from injury. In addition, the following measures are recommended: