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. 2025 Aug 14;232(2):298-307.
doi: 10.1093/infdis/jiae562.

Epidemiologic and Genomic Characterization of an Outbreak of Rift Valley Fever Among Humans and Dairy Cattle in Northern Tanzania

Deng B Madut  1 , Matthew P Rubach  1 , Kathryn J Allan  2 , Kate M Thomas  3 , William A de Glanville  2 , Jo E B Halliday  2 , Cristina Costales  1 , Manuela Carugati  1 , Robert J Rolfe  1 , John P Bonnewell  1 , Michael J Maze  4 , Alex R Mremi  5 , Patrick T Amsi  5 , Nathaniel H Kalengo  5 , Furaha Lyamuya  5 , Grace D Kinabo  5 , Ronald Mbwasi  5 , Kajiru G Kilonzo  6 , Venance P Maro  6 , Blandina T Mmbaga  6 , Bingileki Lwezaula  7 , Calvin Mosha  7 , Annette Marandu  7 , Tito J Kibona  8 , Feng Zhu  9 , Tanu Chawla  9 , Wan Ni Chia  9 , Danielle E Anderson  9 , Lin-Fa Wang  9 , Jie Liu  10 , Eric R Houpt  11 , Roosecelis B Martines  12 , Sherif R Zaki  12 , Austin Leach  13 , Aridth Gibbons  13 , Cheng-Feng Chiang  13 , Ketan Patel  13 , John D Klena  13 , Sarah Cleaveland  2 , John A Crump  3
Affiliations

Epidemiologic and Genomic Characterization of an Outbreak of Rift Valley Fever Among Humans and Dairy Cattle in Northern Tanzania

Deng B Madut et al. J Infect Dis. .

Abstract

Background: A periurban outbreak of Rift Valley fever virus (RVFV) among dairy cattle from May through August 2018 in northern Tanzania was detected through testing samples from prospective livestock abortion surveillance. We sought to identify concurrent human infections, their phylogeny, and epidemiologic characteristics in a cohort of febrile patients enrolled from 2016 to 2019 at hospitals serving the epizootic area.

Methods: From September 2016 through May 2019, we conducted a prospective cohort study that enrolled febrile patients hospitalized at 2 hospitals in Moshi, Tanzania. Archived serum, plasma, or whole blood samples were retrospectively tested for RVFV by PCR. Human samples positive for RVFV were sequenced and compared to RVFV sequences obtained from cattle through a prospective livestock abortion study. Phylogenetic analysis was performed on complete RVFV genomes.

Results: Among 656 human participants, we detected RVFV RNA in 4 (0.6%), including 1 death with hepatic necrosis and other end-organ damage at autopsy. Humans infected with RVFV were enrolled from June through August 2018, and all resided in or near urban areas. Phylogenetic analysis of human and cattle RVFV sequences demonstrated that most clustered to lineage B, a lineage previously described in East Africa. A lineage E strain clustering with lineages in Angola was also identified in cattle.

Conclusions: We provide evidence that an apparently small RVFV outbreak among dairy cattle in northern Tanzania was associated with concurrent severe and fatal infections among humans. Our findings highlight the unidentified scale and diversity of interepizootic RVFV transmission, including near and within an urban area.

Keywords: Africa; Crimean-Congo hemorrhagic fever; Rift Valley fever; Tanzania; zoonoses.

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Conflict of interest statement

Potential conflicts of interest. All authors: No reported conflicts of interest. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.

Figures

Figure 1.
Figure 1.
Flow chart of participant enrollment and testing for Rift Valley fever virus and Crimean-Congo hemorrhagic fever virus in a prospective cohort study evaluating the etiology of severe and fatal febrile illness, Northern Tanzania, 2016–2019. aTaqMan acute febrile illness panel detected RVFV in 3 participants enrolled antemortem. bNext-generation sequencing detected RVFV in 1 participant enrolled postmortem. cComplete genomes available for 11 cattle and 2 human samples. Abbreviations: CCHFV, Crimean-Congo hemorrhagic fever virus; Duke-NUS PEID, Duke-National University of Singapore Program in Emerging Infectious Diseases; KCRI, University of Virginia/Kilimanjaro Clinical Research Institute; RT-qPCR, reverse transcription quantitative polymerase chain reaction; RVFV, Rift Valley fever virus; US CDC VSPD, United States Centers for Disease Control and Prevention Viral Special Pathogen Branch.
Figure 2.
Figure 2.
Epidemic curve illustrating human and cattle Rift Valley fever virus infections detected by RT-qPCR in 2018, Kilimanjaro Region, northern Tanzania, 2016–2019. Abbreviations: RT-qPCR, reverse transcription quantitative polymerase chain reaction; RVFV, Rift Valley fever virus.
Figure 3.
Figure 3.
Location of 4 human and 14 cattle Rift Valley fever virus infections in northern Tanzania: (A) ward location of cases is gray shaded, (B) Tanzania with the Kilimanjaro and Manyara Regions outlined, and (C) Moshi Urban is outlined.
Figure 4.
Figure 4.
Phylogenetic analysis of complete L segment of Rift Valley fever virus strains obtained from infected humans and cattle in northern Tanzania, 2018. The scale bar shows branch length per unit of 0.01 substitutions per site. Sequences are labeled with GenBank accession number and designated strain names with country and year of origin. Sequences from this study and the previous cattle outbreak study are highlighted in bold with unique study identifiers and species of origin. Lineages of viral lineages are labeled according to Bird et al [25].
See this image and copyright information in PMC

References

    1. Daubney R, Hudson JR, Garnham PC. Enzootic hepatitis or Rift Valley fever. An undescribed virus disease of sheep cattle and man from East Africa. J Pathol Bacteriol 1931; 34:545–79.
    1. Bron GM, Strimbu K, Cecilia H, et al. Over 100 years of rift valley fever: a patchwork of data on pathogen spread and spillover. Pathog Basel Switz 2021; 10:708. - PMC - PubMed
    1. Mehand MS, Al-Shorbaji F, Millett P, Murgue B. The WHO R&D Blueprint: 2018 review of emerging infectious diseases requiring urgent research and development efforts. Antiviral Res 2018; 159:63–7. - PMC - PubMed
    1. Nanyingi MO, Munyua P, Kiama SG, et al. A systematic review of Rift Valley fever epidemiology 1931–2014. Infect Ecol Epidemiol 2015; 5:28024. - PMC - PubMed
    1. Gerdes GH. Rift Valley fever. Rev Sci Tech 2004; 23:613–23. - PubMed

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