Human-bat contacts in the Netherlands, and potential risks for virus exchange

Abstract

Background: Contacts between people and free-ranging animals have a potential to cause viral disease epidemics when novel viruses are exchanged. The Netherlands has approximately 18 native bat species, of which some generally use buildings for roosting, and has a dense human population. Frequent indirect and direct contacts between bats and humans could thus be expected, however, this has hardly been studied.

Methods: To study human-bat contacts, people living in the Netherlands were questioned about the type and frequency of their bat contacts, their bat knowledge and perception of bats. For analyses respondents were grouped into (1) general population, (2) bat contact risk group, and (3) people that live in a house with a roost site for a Common Pipistrelle Bat maternity group. Associations between human-bat contacts and other variables were tested by an ordinal logistic regression model.

Results: We show that 85% (226/265) of group 1 reported no contacts, while 11% (28/265) reported indirect, and 4% (11/265) direct contacts with live bats, dead bats or bat products as their closest type of contacts. These contacts occurred mostly less than yearly. Somewhat similarly, the majority, 69% (9/13) of group 3 reported no contacts, and 15% (2/13) reported indirect contacts and 15% (2/13) reported direct contacts. These occurred monthly to less than yearly. In contrast, a minority, 5% (11/227) in group 2 reported no contacts, while 37% (85/227) reported direct bat contacts, mostly yearly, and 38% (86/227) reported bat-related injury, mostly less than yearly, as their closest type of contact. Overall, an increase in knowledge on bats and bat-related diseases was correlated with closer bat contacts.

Conclusions: We conclude that even though bats live close to people in the Netherlands, direct contacts between bats, or bat products, and humans are rare in people from the general population, while being common in people involved in bat-related work. Mitigation of human-bat contacts will be most efficient when targeted to specific groups that are likely to have contacts with bats.

Keywords: Chiroptera; Human-bat interface; Lyssavirus; Questionnaire; Virus; Zoonoses.

Fig. 1

Pie charts showing closest types of bat contact reported by respondents from the general population (A), from the bat contact risk group (B), and residents of houses with Common Pipistrelle Bat maternity groups (C). In the general population (A) most respondents did not report any contacts, while in the bat contact risk group (B) three quarters reported direct bat contacts or injury from bats as their closest contact

Fig. 2

Frequencies of bat contacts per contact type. Percentages of respondents who reported a certain frequency (daily to less than yearly) per contact type, as well as the two most commonly involved bat species. Overall, Common Pipistrelle Bats were the most frequently involved bat species. Probably due to their small teeth and biting force pipistrelles are less likely to cause injury with blood

Fig. 3

Questionnaire results related to rabies prevention in three risk groups. Serotine Bats and Pond Bats are the two species in the Netherlands in which lyssaviruses have been detected. Data show severity of disease is widely underestimated, as is prevention by vaccination. Not all people that had injury from two bat species that might transmit lyssaviruses were vaccinated