Transmission dynamics of Bartonella spp. in cave-dwelling bats and bat flies in Costa Rica Open Access

Abstract

Purpose: This thesis investigated the transmission dynamics of Bartonella spp. in Costa Rican bats and bat flies. The thesis aimed to increase scientific understanding of the prevalence of Bartonella in bat and bat flies, as well as assess spillover risk to humans.

 

Methods: In 2018, 294 individual bats (n=18 species) were sampled using hand nets across 15 roosts throughout the southern and northwestern regions of Costa Rica. Blood samples were obtained from 258 bats and 114 ectoparasites were collected from 48 bats, following an approved IACUC protocol (DAR-4000049-ENTRPR-N). Bat flies were identified taxonomically and pooled by individual bat host and bat fly species (n=63 pools), and DNA was extracted from blood and ectoparasite samples. Samples were screened for Bartonella via polymerase chain reaction (PCR) targeting the gltA citrate synthase gene. PCR-positive samples were sequenced. Phylogenetic trees comparing these isolates to previously identified Central American and globally named strains were stratified by country and constructed using Bayesian MCMC analyses, executed by MrBayes 3.2.6. A complete tree was constructed with 10,000,000 generations and a burn-in fraction of 25%.

 

Results: Bartonella PCR-prevalence from all samples was 14.6% (47/321). Bartonella PCR-prevalence was 10.4% (27/258) for bats and 31.7% (20/63) for ectoparasite pools. Bartonella isolates from bats (n = 8) and bat flies (n= 5) were included in phylogenetic analyses, which revealed 11 genetic variants, including four newly described genotypes. These 11 genetic variants clustered into nine clades of 96.0%-99.2% similarity. Bat and bat fly genotypes from this study clustered with previously identified Bartonella sequences from bats and bat flies from Belize, Guatemala and Costa Rica. Four clades were unique to this study.

 

Conclusions: This thesis expanded upon existing knowledge of the diversity and prevalence of Bartonella in Costa Rican bats and bat flies. Bartonella were more prevalent in bat flies than bats. Identical Bartonella strains were found in bats and bat flies, suggesting potential for sharing of the pathogen. Geographic and host associations were observed among Bartonella strains from bats and bat flies from Central America; however, significant areas of overlap were also observed.

Table of Contents

1. Introduction …………………………………………………………………………...1-11

1.1. Overview & Significance …………………………………………………..1-3

1.2. Background: Bartonella species in bats and bat flies in Central America.....4-10

1.3. Goals, Questions & Hypothesis……………………………………………..11

2. Materials and Methods.……………………………………………………………….11-15

2.1. Study Design, Methods of Data Collection, and Sites.…………………….11-12

2.2. Molecular Analysis.………………………………………………………..12-13

2.3. Sequencing and Phylogenetic Analysis……………………………………14-15

3. Results………………………………………………………………………………...15-24

3.1. Sample Size………………..………………………………………….…....15-16

3.2. PCR Prevalence…………………………………………………………….16-18

3.3. Phylogeny of bat and bat fly Bartonella isolates.…………………………..18-24

4. Discussion……………………………………………………………………………..24-31

5. Conclusions and Recommendations……………………………………………………………………..31-32

6. References ………………………………………………………………………….....32-37

7. Tables ………………………………………………………………………………....38-48

Table 1.……………………………………………………………………..38-39

Table 2.……………………………………………………………………..40

Table 3.……………………………………………………………………..41

Table 4.……………………………………………………………………..42-43

Table 5.……………………………………………………………………..44-47

8. Figures …………………………………………………………………………….......49-57

Figure 1.…………………………………………………………………….49

Figure 2.…………………………………………………………………….50

Figure 3.…………………………………………………………………….51

Figure 4……………………………………………………………………..52

Figure 5……………………………………………………………………..53

Figure 6……………………………………………………………………..54

Figure 7……………………………………………………………………..55

Figure 8……………………………………………………………………..56-57

About this Master's Thesis

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School	Rollins School of Public Health
Department	Environmental Health
Degree	M.P.H.
Submission	Master's Thesis
Language	English
Research Field	Environmental Studies Health Sciences, Public Health Biology, Molecular
Keyword	Zoonoses Infectious Disease Phylogenetic Analysis Ectoparasites Parasitism Bartonella Bats
Committee Chair / Thesis Advisor	Thomas R. Gillespie, Emory University
Committee Members	Amanda Vicente-Santos, Emory University

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