Febrile patients admitted to remote hospitals in Northeastern Kenya: seroprevalence, risk factors and a clinical prediction tool for Q-Fever

Abstract

BackgroundQ fever in Kenya is poorly reported and its surveillance is highly neglected. Standard empiric treatment for febrile patients admitted to hospitals is antimalarials or penicillin-based antibiotics, which have no activity against Coxiella burnetii. This study aimed to assess the seroprevalence and the predisposing risk factors for Q fever infection in febrile patients from a pastoralist population, and derive a model for clinical prediction of febrile patients with acute Q fever.MethodsEpidemiological and clinical data were obtained from 1067 patients from Northeastern Kenya and their sera tested for IgG antibodies against Coxiella burnetii antigens by enzyme-linked-immunosorbent assay (ELISA), indirect immunofluorescence assay (IFA) and quantitative real-time PCR (qPCR). Logit models were built for risk factor analysis, and diagnostic prediction score generated and validated in two separate cohorts of patients.ResultsOverall 204 (19.1 %, 95 % CI: 16.8–21.6) sera were positive for IgG antibodies against phase I and/or phase II antigens or Coxiella burnetii IS1111 by qPCR. Acute Q fever was established in 173 (16.2 %, 95 % CI: 14.1–18.7) patients. Q fever was not suspected by the treating clinicians in any of those patients, instead working diagnosis was fever of unknown origin or common tropical fevers. Exposure to cattle (adjusted odds ratio [aOR]: 2.09, 95 % CI: 1.73–5.98), goats (aOR: 3.74, 95 % CI: 2.52–9.40), and animal slaughter (aOR: 1.78, 95 % CI: 1.09–2.91) were significant risk factors. Consumption of unpasteurized cattle milk (aOR: 2.49, 95 % CI: 1.48–4.21) and locally fermented milk products (aOR: 1.66, 95 % CI: 1.19–4.37) were dietary factors associated with seropositivity. Based on regression coefficients, we calculated a diagnostic score with a sensitivity 93.1 % and specificity 76.1 % at cut off value of 2.90: fever >14 days (+3.6), abdominal pain (+0.8), respiratory tract infection (+1.0) and diarrhoea (−1.1).ConclusionQ fever is common in febrile Kenyan patients but underappreciated as a cause of community-acquired febrile illness. The utility of Q fever score and screening patients for the risky social-economic and dietary practices can provide a valuable tool to clinicians in identifying patients to strongly consider for detailed Q fever investigation and follow up on admission, and making therapeutic decisions.

Serosurvey ofCoxiella burnetii(Q fever) in Dromedary Camels(Camelus dromedarius)in Laikipia County, Kenya

“…Efforts should be made on a local, regional and national level to educate consumers and camel owners about mitigating the risk of this pathogen. Recent research in Northeastern Kenya revealed that 16.2% of febrile patients admitted to remote hospitals suffered from acute Q fever infection, but Q fever was not suspected by any of the treating physicians and 99.5% of the febrile patients had no knowledge of Q fever (Njeru et al., ).…”

“…In Kenya, knowledge of Q fever is lacking although two studies found a 26.8% and 30.6% seroprevalence among humans tested for C. burnetii antibodies (Knobel et al., ; Mwololo et al., ). More recent research revealed that 16.2% of febrile patients admitted to hospitals in Northeastern Kenya were suffering from acute Q fever (Njeru et al., ).…”

Coxiella burnetii Antibody Prevalence and Risk Factors of Infection in the Human Population of Estonia

“…The IFA has been shown to be the most sensitive and specific test for C. burnetii antibody detection, but since IFA testing is more laborious, combining ELISA as a primary screening test and IFA as a confirmatory test has been suggested for large-scale population studies [14].Domestic ruminants are considered one of the main infection sources for humans [13,[15][16][17][18][19][20]. The infection transmits to humans mainly through the inhalation of aerosols containing C. burnetii [13,15,19,21] or via direct contact with infected animals [22,23]. In lactating animals, the bacterium is excreted in the milk [24][25][26], and consuming unpasteurized goat's milk, cow's milk, or raw milk products is a risk factor for acquiring the infection [18,23,27].…”

“…The infection transmits to humans mainly through the inhalation of aerosols containing C. burnetii [13,15,19,21] or via direct contact with infected animals [22,23]. In lactating animals, the bacterium is excreted in the milk [24][25][26], and consuming unpasteurized goat's milk, cow's milk, or raw milk products is a risk factor for acquiring the infection [18,23,27]. Coxiella burnetii produces small spore-like forms [28] that enable the pathogen to survive in the environment for long periods of time [29,30].…”

“…Some environmental and meteorological conditions increase the risk of infection, such as higher wind speeds, soil, and landscapes being more sensitive to wind erosion and low rainfall [15,21,31]. A number of animal species, including pets [32][33][34][35], horses [36,37], birds [38], wildlife, and arthropods (mainly ticks) [39][40][41][42], might also play a role in spreading C. burnetii.The main risk factors for human infection are direct or indirect contact with parturient ruminants [13,19,23,43] and traveling or working in areas where the pathogen is endemic [44][45][46]. Farm and abattoir personnel, along with veterinarians, are occupations considered to be at a higher risk of getting the infection due to the contact with animals [8][9][10]18,47,48].…”