Rickettsiosis is a re-emergent infectious disease without epidemiological surveillance in Colombia. This disease is generally undiagnosed and several deadly outbreaks have been reported in the country in the last decade. The aim of this study is to analyze the eco-epidemiological aspects of rickettsial seropositivity in rural areas of Colombia where outbreaks of the disease were previously reported. A cross-sectional study, which included 597 people living in 246 households from nine hamlets in two municipalities of Colombia, was conducted from November 2015 to January 2016. The survey was conducted to collect sociodemographic and household characteristics (exposure) data. Blood samples were collected to determine the rickettsial seropositivity in humans, horses and dogs (IFA, cut-off = 1/128). In addition, infections by rickettsiae were detected in ticks from humans and animals by real-time PCR targeting gltA and ompA genes. Data was analyzed by weighted multilevel clog-log regression model using three levels (person, household and hamlets) and rickettsial seropositivity in humans was the main outcome. Overall prevalence of rickettsial seropositivity in humans was 25.62% (95%CI 22.11–29.12). Age in years (PR = 1.01 95%CI 1.01–1.02) and male sex (PR = 1.65 95%CI 1.43–1.90) were risk markers for rickettsial seropositivity. Working outdoors (PR = 1.20 95%CI 1.02–1.41), deforestation and forest fragmentation for agriculture use (PR = 1.75 95%CI 1.51–2.02), opossum in peridomiciliary area (PR = 1.56 95%CI 1.37–1.79) and a high proportion of seropositive domestic animals in the home (PR20-40% vs <20% = 2.28 95%CI 1.59–3.23 and PR>40% vs <20% = 3.14 95%CI 2.43–4.04) were associated with rickettsial seropositivity in humans. This study showed the presence of Rickettsia antibodies in human populations and domestic animals. In addition, different species of rickettsiae were detected in ticks collected from humans and animals. Our results highlighted the role of domestic animals as sentinels of rickettsial infection to identify areas at risk of transmission, and the importance of preventive measures aimed at curtailing deforestation and the fragmentation of forests as a way of reducing the risk of transmission of emergent and re-emergent pathogens.

IntroductionMost of the studies related to rickettsial infection in Colombia are cross-sectional because of the challenge in conducting prospective studies on infectious disease that may have a difficult diagnosis. Although cross-sectional studies are essential to detect people exposed to rickettsiae, they are not suited to demonstrate the recent circulation of this pathogen in areas at risk of transmission.ObjectiveTo characterize the epidemiology of incident cases of Spotted fever group (SFG) rickettsial infection in humans and equines from rural areas of Urabá region in Colombia where outbreaks of rickettsiae previously occurred.Materials and methodsA prospective study was conducted in the Alto de Mulatos and Las Changas in the Urabá region. Serum samples and socio-ecological information were collected from 597 people enrolled in 2015, and a second sample was collected from 273 people a year later. Indirect immune-fluorescence assays for detection of IgG antibody against rickettsiae were done using slides with Rickettsia rickettsii antigens. A titer ≥128 was considered positive. Incident cases were defined as (i) serological conversion of IgG titers from seronegative to seropositive or (ii) at least a four-fold increase in IgG end point titers in the second sample.ResultsThe cumulative incidence of rickettsial infection was 6.23% (95%CI 3.67–9.78) in humans and 32.31% (21/65) of incident cases in equines. Incident cases were mostly females (82.35%), the median age of cases was 41.02 years (IQR 18.62–54.1), and 29.41% reported tick bites during the study period. Results from multivariate analysis showed that removal of ticks after working outdoors is a protective factor for rickettsial infection (RR 0.26, 95%CI 0.08–0.84) and that a higher incidence of infection occurred in people who reported fever in the last year (RR 4.26, 95%CI 1.15–9.31).ConclusionsThese results showed recent circulation of SFG rickettsiae in areas where previous lethal outbreaks have been reported, supporting the implementation of preventive measures to halt rickettsial transmission in the studied communities.

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Um inquérito entomològico foi realizado na área de influência da Hidrelétrica de Balbina, situada a 146 km de Manaus, Amazonas, para avaliar os possíveis efeitos sobre as populações de Anophelese de outros culicídeos. Cinco anos após a formação do lago, An. darlingi, An. nuneztovarie An. triannulatusforam as espécies encontradas com maior freqüência nas coletas realizadas em 1. Rodovia BR-174, 2. Acceso á Usina Hidrelétrica de Balbina e 3. Área Uatumã-Morena. Para cada espécie os índices mosquito/homem/hora foram respectivamente: Area 1 - 0,57; 12,85; 0,43. Área 2 - 0; 3,75; 0,18 e Área 3 - 0; 26,38; 0,34. Representantes das duas primeiras espécies se mostraram positivas para Plasmodiumcom testes imunoenzimáticos. A prevalência de mosquitos positivos foi 1:35 para An. darlingie apenas 1:548 para An. nuneztovari.A densidade dos outros culicídeos foi baixa (Área 1 - 3,23 m/h/h; Área 2 - 4,5 m/h/h; Área 3 - 7,40 m/h/h) embora a diversidade foi comparável ( 32 espécies diferentes) com as encontradas em outras hidrelétricas construídas em rios de águas brancas ou claras da Amazônia. Nas águas pretas da Balbina, uma proliferação inicial de macrófitas foi seguida pela redução destas possivelmente pela falta de nutrientes na água. A diminuição no crescimento de macrófitas deve estar relacionada com a escassez de Mansoniasp. na área.

This study aimed to analyze epidemiological indicators related to seroprevalent and seroincident cases of spotted fever group rickettsiae (SFGR) and to identify housing conditions related to tick infestation. A prospective study (2016–2018) was conducted to examine rickettsial seropositivity in humans, domestic animals, and wild mammals in the municipality of Uramita, Antioquia, Colombia, where a previous Rickettsia rickettsii outbreak was reported from 2014 to 2015. The seroprevalence and its associated factors were estimated at baseline, and the seroincidence and its risk factors for humans were estimated 20 months later. A cross-sectional analysis was performed to evaluate the housing conditions linked to tick infestation. The SFGR seroprevalence was 26.70% (95% confidence interval [CI], 20.79–31.37), and the factors associated with SFGR seropositivity were male sex (adjusted prevalence ratio [PRa], 1.67; 95% CI, 1.19–2.32), age (evaluated in 5-year increments) (PRa, 1.05; 95% CI, 1.01–1.09), and household proximity (PRascattered versus very near=3.87; 95% CI, 1.12–8.66). The overall seroincidence was 7.40% (95% CI, 4.71–11.06), and the factors associated with SFGR seroincident cases were the presence of wild animals (adjusted relative risk [RRa], 2.46; 95% CI, 1.06–4.72) and the presence of trees in the peri-domiciliary area (RRa, 0.47; 95% CI, 0.23–0.94). The prevalence of house tick infestation was 27.81% (95% CI, 21.93–34.80), and the factors associated with infestation were dirt floors (PRa, 5.88; 95% CI, 2.28–10.31), fiber cement roofs (PRa, 1.76; 95% CI, 1.07–2.83), and the presence of canines in peri-domiciliary or intra-domiciliary areas (PRa, 5.05; 95% CI, 3.31–7.19). Seropositivity rates for canines and opossums were 35.62% (26/73) and 100% (6/6), respectively. Identification of these factors will help to implement efficient surveillance programs in Colombia.

Introduction: In 2006 and 2008 there were two lethal outbreaks of rickettsioses in the rural areas of Urabá, characterized by the lack of immediate diagnosis and antibiotic treatment. Objective: Describe sociocultural aspects about knowledge, attitudes and practices in relation to febrile syndromes and “tick fever” in rural areas of Urabá. Materials and methods: We conducted an exploratory study using knowledge, attitudes, and practices questionnaires and semi-structured interviews about febrile syndromes and “tick fever”. We surveyed 246 heads of households and interviewed nine individuals. Results: We observed that people tended to identify febrile syndromes with signs and clinical symptoms of dengue, malaria, leptospirosis and rickettsioses. A considerable proportion of individuals (32.93%) knew very little about “tick fever”, thinking that is was transmitted by mosquitos. They mentioned intestinal parasitoids, malaria, dengue, and “evil eye” among the causes of febrile syndromes. “Tick fever” is linked by its name to the bite of the tick. Furthermore, the treatments for febrile syndromes mentioned by interviewees are associated to those commonly used in western medicine and medicinal plants. Conclusions: There is a need for educational programs in rural areas, to raise awareness about these potential lethal conditions that can be effectively treated.