Volume 29, Number 2—February 2023
Bartonella spp. and Typhus Group Rickettsiae among Persons Experiencing Homelessness, São Paulo, Brazil
Persons experiencing homelessness in São Paulo, Brazil, were seropositive for Bartonella spp. (79/109, 72.5%) and typhus group rickettsiae (40/109, 36.7%). Bartonella quintana DNA was detected in 17.1% (14/82) body louse pools and 0.9% (1/114) blood samples. Clinicians should consider vectorborne agents as potential causes of febrile syndromes in this population.
Persons experiencing homelessness might be predisposed to vectorborne infections because of increased exposure to ectoparasites (1). Members of the genera Bartonella and Rickettsia, particularly the louseborne pathogens B. quintana and R. prowazekii, are agents of emerging illnesses among persons who are marginalized or experiencing homelessness (1). Studies on Bartonella and Rickettsia spp. infections in homeless populations within Latin America are scarce (2,3). Infestations with Pediculus humanus humanus body lice were reported in persons experiencing homelessness in Curitiba and São Paulo, 2 major cities in Brazil (4). We report results of molecular testing of lice and blood from persons experiencing homelessness in the city of São Paulo in southeastern Brazil. We evaluated their possible exposure to Bartonella spp. and typhus group rickettsiae (TGR) by using indirect immunofluorescence assays (IFAs). In addition, we assessed risk factors related to serologic status.
During June–August 2018, a total of 114 persons experiencing homelessness (101 men, 13 women; average age 42.5 ±13.4 years) from a day-shelter in the city of São Paulo signed written informed consent forms and participated in this study, which was approved by the National Ethics Committee in Human Research (protocol no. 80099017.3.0000.0102). Persons responded to a questionnaire that, combined with medical and demographic records (Appendix), we used to assess risk factors. We carefully examined personal clothing and found lice in 14.9% (17/114, 95% CI 6.9%–19.7%) of persons; the lice were taxonomically identified as P. humanus humanus (5).
We analyzed 109 serum samples from study participants by using IFA to detect IgG against Bartonella spp. and TGR. We used commercial slides for B. quintana (12-well IFA Substrate Slides; Fuller Laboratories, http://www.fullerlaboratories.com) and in-house slides for B. henselae sequence type 9, B. machadoae 56A, R. typhi Galveston, and R. prowazekii Breinl strains. We found 79/109 (72.5%, 95% CI 63.1%–80.1%) persons were seropositive for Bartonella spp. and 40/109 (36.7%, 95% CI 27.7%–46.5%) were seropositive for TGR (titers >64). All antibody titers were >128 (Appendix Table 1), except for 2 B. quintana–positive and 8 TGR-positive samples. An endpoint titer >4-fold higher for a particular Bartonella/Rickettsia spp. antigen than that observed for other Bartonella/Rickettsia spp. antigens was considered the possible antigen involved in a homologous reaction (PAIHR) (6). Thus, B. quintana was the PAIHR in 75/79 (95.0%, 95% CI 87.5%–98.6%) persons, R. typhi was the PAIHR in 13/40 (32.5%, 95% CI 18.6%–49.1%) persons, and R. prowazekii was the PAIHR in 3/40 (7.5%, 95% CI 1.6%–20.4%) persons (Appendix Table 1).
We extracted DNA by using the Blood/Tissue DNA Kit (MEBEP Bio Science, https://www.mebep.com) for 114 blood samples and guanidine isothiocyanate and phenol/chloroform technique (7) for 638 lice (82 pools). We confirmed successful extractions by PCR of glyceraldehyde-3-phosphate dehydrogenase (blood) and invertebrate mitochondrial cytochrome c oxidase subunit I (lice) genes (8,9). We screened DNA samples for Bartonella spp. by PCR of citrate synthase (gltA) and β subunit of RNA polymerase (rpoB) genes and for Rickettsia spp. by PCR of rickettsial 17-kDa antigen gene, as previously described (10–12). We used ultrapure water as a negative control and genomic DNA from B. henselae and R. sibirica as positive controls. A total of 14/82 (17.0%, 95% CI 9.7%–27.0%) louse pools and 1/114 (0.9%, 95% CI 0.02%–4.8%) blood samples were positive for gltA and rpoB but negative for Rickettsia spp. (Appendix Table 2).
Amplicons were purified and sequenced at the University of Texas Medical Branch (Galveston, TX, USA). The gltA and rpoB sequences showed 100% identity to B. quintana strain NCTC12899 (GenBank accession no. LS483373.1) by BLASTn analysis (https://blast.ncbi.nlm.nih.gov). B. quintana sequences generated in this study were deposited in GenBank (accession nos. ON808843 and ON808844). The person whose blood was PCR-positive for B. quintana was not infested with body lice but demonstrated high levels of IgG against B. quintana (titer >1,024) and TGR (titers were 1,024 for R. typhi and 512 for R. prowazekii).
We chose risk factor variables by using unconditional logistic regression models (p<0.25) and conditional logistic regression to determine relationships between putative risk factors and serologic status. We used Bayesian information criteria to assess the goodness-of-fit for the models. We used R software version 4.1.2 (The R Project for Statistical Computing, https://www.r-project.org) for all statistical analyses and summarized the final conditional logistic regression model (Table). Although the final model for Bartonella spp. revealed 3 variables, only 1 was statistically significant and showed an association between body louse infestation and higher risk for Bartonella spp. seropositivity (OR [odds ratio] 2.9, 90% CI 1.1–8.1). The final TGR model contained 5 variables of which 3 were associated with higher seropositivity risk, including self-identifying as white (OR 3.9, 90% CI 1.6–10.7), syphilis seropositivity (OR 3.6, 90% CI 1.5–9.4), and homelessness because of unemployment (OR 2.3, 90% CI 1.02–5.5). We detected 5 variables for combined Bartonella spp. and TGR of which 4 variables were associated with seropositivity, including self-identifying as white (OR 5.6, 90% CI 2.2–15.5), monthly change of clothes (OR 0.08, 90% CI 0.07–0.4), homelessness because of family conflicts (OR 0.4, 90% CI 0.2–0.8), and higher total plasma protein (OR 2.0, 90% CI 1.1–4.0).
Our study revealed Bartonella spp. and TGR exposure, associated risk factors related to serologic status, and B. quintana detection in lice and one blood sample among persons experiencing homelessness in São Paulo, Brazil. Seroprevalence of Bartonella spp. (72.5%) was higher in our study than previous reports for persons experiencing homelessness (1.8%–65%) (13), and B. quintana was the dominant antigen involved in homologous reactions. The highest B. quintana seroprevalence was previously found in France (65%, antibody titers >100) and Japan (57%, titers >128) (13); those titers were considered indicative of previous exposure. In our study, the antibody titer cutoff was >64, explaining our high seroprevalence results, although all but 2 titers were >128. TGR seropositivity in our study (36.7%) was within the range observed in the United States, Europe, and Colombia (0.54%–56.2%) (1,3).
Persons experiencing homelessness in São Paulo had P. humanus humanus body louse infestation and seropositivity for B. quintana and TGR similar to that reported previously (1). Body louse infestation (14.9%) was within the range of other reports (7%–22%) (14), highlighting global vulnerability to louse infestation and louseborne diseases in persons experiencing homelessness (1).
Through logistic regression, we showed seropositivity for Bartonella spp. was associated with louse infestation. Because the association of white ethnicity and TRG seropositivity (alone and in combination with Bartonella spp.) might be from a skewed population sampling, our findings should be further investigated. Nonetheless, higher TGR seropositivity was associated with homelessness because of unemployment, duration of homelessness, and syphilis seropositivity, which represent risk factors that reflect vulnerability and socioeconomic conditions. In addition, seropositivity for both Bartonella and TGR was associated with infrequent changes of clothing.
The first limitation of our study is that the small sample size and power for the examined variables might have weakened associations of Bartonella seroreactivity with other variables included in our questionnaire, such as alcoholism, tobacco or intravenous drug use, and homelessness as previously reported (15), and variables that were significant in univariate analysis. In addition, IgG seropositivity reflects past Bartonella and TGR infections (6,13). IFA cross-reactivity should be addressed with future studies by using cross-adsorption techniques.
Our results should alert public health professionals in the city of São Paulo to initiate preemptive measures and active vector control among persons experiencing homelessness and confirm circulation of Bartonella and TGR species. Clinicians should also consider these vectorborne agents as probable etiologic agents of febrile syndromes in this vulnerable population.
Dr. Faccini-Martínez is a researcher and physician. His primary research interests focus on zoonotic and vectorborne diseases.
We thank Sandro Ricardo Ruys and the Community Center of São Martinho de Lima for help with collection, sampling, and follow-up information and Nicole Mendell and Donald H. Bouyer for providing genomic DNA of Bartonella henselae and Rickettsia sibirica that was used as positive controls for PCR.
During this study, Á.A.F.-M. was supported by the Fogarty International Center and National Institute of Allergy and Infectious Diseases of the US National Institutes of Health (award no. D43 TW010331). The content is solely the authors’ responsibility and does not necessarily represent the official views of the National Institutes of Health.
- Leibler JH, Zakhour CM, Gadhoke P, Gaeta JM. Zoonotic and vector-borne infections among urban homeless and marginalized people in the United States and Europe, 1990–2014. Vector Borne Zoonotic Dis. 2016;16:435–44.
- Alcantara V, Rolain JM, Eduardo AG, Raul MJ, Raoult D. Molecular detection of Bartonella quintana in human body lice from Mexico City. Clin Microbiol Infect. 2009;15(Suppl 2):93–4.
- Faccini-Martínez ÁA, Márquez AC, Bravo-Estupiñan DM, Calixto O-J, López-Castillo CA, Botero-García CA, et al. Bartonella quintana and typhus group rickettsiae exposure among homeless persons, Bogotá, Colombia. Emerg Infect Dis. 2017;23:1876–9.
- Gravinatti ML, Faccini-Martínez ÁA, Ruys SR, Timenetsky J, Biondo AW. Preliminary report of body lice infesting homeless people in Brazil. Rev Inst Med Trop São Paulo. 2018;60:
- Centers for Disease Control and Prevention. Anoplura: pictorial key to some common genera of sucking lice [cited 2022 Oct 21]. https://www.cdc.gov/nceh/ehs/docs/pictorial_keys/lice-anoplura.pdf
- Portillo A, de Sousa R, Santibáñez S, Duarte A, Edouard S, Fonseca IP, et al. Guidelines for the detection of Rickettsia spp. Vector Borne Zoonotic Dis. 2017;17:23–32.
- Sangioni LA, Horta MC, Vianna MCB, Gennari SM, Soares RM, Galvão MAM, et al. Rickettsial infection in animals and Brazilian spotted fever endemicity. Emerg Infect Dis. 2005;11:265–70.
- Folmer O, Black M, Hoeh W, Lutz R, Vrijenhoek R. DNA primers for amplification of mitochondrial cytochrome c oxidase subunit I from diverse metazoan invertebrates. Mol Mar Biol Biotechnol. 1994;3:294–9.
- Tan B, Li Y, Zhao Q, Fan L, Liu Y, Wang D, et al. Inhibition of Vav3 could reverse the drug resistance of gastric cancer cells by downregulating JNK signaling pathway. Cancer Gene Ther. 2014;21:526–31.
- Logan JMJ, Hall JL, Chalker VJ, O’Connell B, Birtles RJ. Bartonella clarridgeiae infection in a patient with aortic root abscess and endocarditis. Access Microbiol. 2019;1:
- Renesto P, Gouvernet J, Drancourt M, Roux V, Raoult D. Use of rpoB gene analysis for detection and identification of Bartonella species. J Clin Microbiol. 2001;39:430–7.
- Webb L, Carl M, Malloy DC, Dasch GA, Azad AF. Detection of murine typhus infection in fleas by using the polymerase chain reaction. J Clin Microbiol. 1990;28:530–4.
- Mai BH. Seroprevalence of Bartonella quintana infection: a systematic review. J Glob Infect Dis. 2022;14:50–6.
- Badiaga S, Raoult D, Brouqui P. Preventing and controlling emerging and reemerging transmissible diseases in the homeless. Emerg Infect Dis. 2008;14:1353–9.
- Jackson LA, Spach DH, Kippen DA, Sugg NK, Regnery RL, Sayers MH, et al. Seroprevalence to Bartonella quintana among patients at a community clinic in downtown Seattle. J Infect Dis. 1996;173:1023–6.
TableCite This Article
Original Publication Date: January 16, 2023