Browsing by Author "Christina, Douglas"

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    Seroprevalence of Q-fever, spotted fever, typhus group Rickettsia and Orientia among febrile patients visiting hospital-based sentinel sites in Uganda
    (PAMJ - One Health, 2023) Eneku, Wilfred; Erima, Bernard; Byaruhanga, Anatoli Maranda; Nora, Gillian Cleary; Atim, Gladys; Tugume, Titus; Ukuli, Qouilazoni Aquino; Kibuuka, Hannah; Mworozi, Edison; Christina, Douglas; Jeffrey, William Koehler; Michael, Emery von Fricken; Biryomumaisho, Savino; Tweyongyere, Robert; Wabwire-Mangen, Fred; Byarugaba, Denis Karuhize
    Introduction: rickettsioses are emerging zoonotic febrile illnesses transmitted to humans by ticks, fleas, lice, and mites. Q-fever, Spotted fever group (SFG), Typhus group (TG) rickettsia and Scrub typhus (STG) have been reported with varying prevalence across East Africa. However, little is known about the burden of exposure in Uganda. The aim of this study was to determine the seroprevalence and associated risk factors of rickettsial diseases in Uganda. Methods: a total of 460 archived serum samples collected from patients with fever of unknown origin after screening across five hospital-based sentinel sites were analysed. The samples were collected during 18-month period of active surveillance for acute febrile illnesses, from January 2018 through June 2019. We performed IgM ELISA tests on the 460 sera for SFG and TG rickettsia, IgM IFA for STG and Phase 2 IgG ELISA for Q-fever. We also assessed risk factors associated with the serostatus. Results: the population comprised predominantly children, had balanced gender proportions, with 66% coming from rural areas. The overall seroprevalence of SFG rickettsiosis was 6.3%; however, 11.5% and 10.8% prevalence rates were observed in Gulu and Bwera hospitals respectively. This was higher than the 3.7% observed in the capital city Kampala, although the differences were not statistically significant (Fisher's exact = 0.489). Overall seropositivity of Q-fever was 7.6%, although Bwera Hospital had the highest rate (12.5%) and Mulago had the lowest rate (2%). The differences were not considered statistically significant (Fishers exact= 0.075). Increasing age (OR-adjusted=1.4, 95%CI=1.0-1.9, p=0.026) and rural background (OR-adjusted=2.6, 95%CI=1.6- 6.4, p=0.037) were both significantly associated with seropositivity for Q-fever, while only increasing age had higher odds for seropositivity for SFG rickettsia (OR-adjusted= 1.9, 95% CI= 1.4- 2.6, p<0.001). One serum sample of a 10-monthold male from Bwera hospital was reactive to both SFG and Q-fever antibodies. We found four sera reactive cases to typhus group IgM and another four reactive to Orientia spp. IgM. However, we were not able to determine associating factors due to low seropositivity rates. Conclusion: here, we report for the first time the seroprevalence of Qfever, SFG and STG in febrile patients in Uganda. This report also provides the second study in over five decades since the earliest report of TG rickettsia. Testing for these pathogens in patients with acute febrile illness with unknown etiology may hold value, however more studies are required to provide information on disease ecology, risk factors, and transmission dynamics of these pathogens in Uganda.
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    Wide distribution of Mediterranean and African spotted fever agents and the first identification of Israeli spotted fever agent in ticks in Uganda
    (PLOS NEGLECTED TROPICAL DISEASES, 2023) Eneku, Wilfred; Erima, Bernard; Maranda Byaruhanga, Anatoli; Atim, Gladys; Tugume, Titus; Ukuli, Qouilazoni A.; Kibuuka, Hannah; Mworozi, Edison; Christina, Douglas; Jeffrey, W. Koehler; Nora, G. Cleary; Michael, E. von Fricken; Tweyongyere, Robert; Wabwire-Mangen, Fred; Karuhize Byarugaba, Denis
    Rickettsia microorganisms are causative agents of several neglected emerging infectious diseases in humans transmitted by arthropods including ticks. In this study, ticks were collected from four geographical regions of Uganda and pooled in sizes of 1–179 ticks based on location, tick species, life stage, host, and time of collection. Then, they were tested by real-time PCR for Rickettsia species with primers targeting gltA, 17kDa and ompA genes, followed by Sanger sequencing of the 17kDa and ompA genes. Of the 471 tick pools tested, 116 (24.6%) were positive for Rickettsia spp. by the gltA primers. The prevalence of Rickettsia varied by district with Gulu recording the highest (30.1%) followed by Luwero (28.1%) and Kasese had the lowest (14%). Tick pools from livestock (cattle, goats, sheep, and pigs) had the highest positivity rate, 26.9%, followed by vegetation, 23.1%, and pets (dogs and cats), 19.7%. Of 116 gltA-positive tick pools, 86 pools were positive using 17kDa primers of which 48 purified PCR products were successfully sequenced. The predominant Rickettsia spp. identified was R. africae (n = 15) in four tick species, followed by R. conorii (n = 5) in three tick species (Haemaphysalis elliptica, Rhipicephalus appendiculatus, and Rh. decoloratus). Rickettsia conorii subsp. israelensis was detected in one tick pool. These findings indicate that multiple Rickettsia spp. capable of causing human illness are circulating in the four diverse geographical regions of Uganda including new strains previously known to occur in the Mediterranean region. Physicians should be informed about Rickettsia spp. as potential causes of acute febrile illnesses in these regions. Continued and expanded surveillance is essential to further identify and locate potential hotspots with Rickettsia spp. of concern.