• Cholera Epidemic in South Sudan and Uganda and Need for International Collaboration in Cholera Control

      Abubakar, A; Bwire, G; Azman, AS; Bouhenia, M; Deng, LL; Wamala, JF; Rumunu, J; Kagirita, A; Rauzier, J; Grout, L; et al. (Center for Disease Control, 2018-05-01)
    • Effectiveness of One Dose of Oral Cholera Vaccine in Response to an Outbreak: A Case-Cohort Study

      Azman, AS; Parker, LA; Rumunu, J; Tadesse, F; Grandesso, F; Deng, LL; Lino, RL; Bior, BK; Lasuba, M; Page, AL; et al. (Elsevier, 2016-11-01)
      Oral cholera vaccines represent a new effective tool to fight cholera and are licensed as two-dose regimens with 2-4 weeks between doses. Evidence from previous studies suggests that a single dose of oral cholera vaccine might provide substantial direct protection against cholera. During a cholera outbreak in May, 2015, in Juba, South Sudan, the Ministry of Health, Médecins Sans Frontières, and partners engaged in the first field deployment of a single dose of oral cholera vaccine to enhance the outbreak response. We did a vaccine effectiveness study in conjunction with this large public health intervention.
    • Genomic Insights into the 2016-2017 Cholera Epidemic in Yemen

      Weill, FX; Domman, D; Njamkepo, E; Almesbahi, AA; Naji, M; Nasher, SS; Rakesh, A; Assiri, AM; Sharma, NC; Kariuki, S; et al. (Nature Publishing Group, 2019-01-02)
      Yemen is currently experiencing, to our knowledge, the largest cholera epidemic in recent history. The first cases were declared in September 2016, and over 1.1 million cases and 2,300 deaths have since been reported1. Here we investigate the phylogenetic relationships, pathogenesis and determinants of antimicrobial resistance by sequencing the genomes of Vibrio cholerae isolates from the epidemic in Yemen and recent isolates from neighbouring regions. These 116 genomic sequences were placed within the phylogenetic context of a global collection of 1,087 isolates of the seventh pandemic V. cholerae serogroups O1 and O139 biotype El Tor2-4. We show that the isolates from Yemen that were collected during the two epidemiological waves of the epidemic1-the first between 28 September 2016 and 23 April 2017 (25,839 suspected cases) and the second beginning on 24 April 2017 (more than 1 million suspected cases)-are V. cholerae serotype Ogawa isolates from a single sublineage of the seventh pandemic V. cholerae O1 El Tor (7PET) lineage. Using genomic approaches, we link the epidemic in Yemen to global radiations of pandemic V. cholerae and show that this sublineage originated from South Asia and that it caused outbreaks in East Africa before appearing in Yemen. Furthermore, we show that the isolates from Yemen are susceptible to several antibiotics that are commonly used to treat cholera and to polymyxin B, resistance to which is used as a marker of the El Tor biotype.
    • High Prevalence of Shigella or Enteroinvasive Escherichia coli Carriage among Residents of an Internally Displaced Persons Camp in South Sudan

      Bliss, J; Bouhenia, M; Hale, P; Couturier, BA; Iyer, AS; Rumunu, J; Martin, S; Wamala, JF; Abubakar, A; Sack, DA; et al. (American Society of Tropical Medicine and Hygiene, 2017-12-04)
      Displaced persons living in camps are at an increased risk of diarrheal diseases. Subclinical carriage of pathogens may contribute to the spread of disease, especially for microbes that require a low infectious dose. Multiplex real-time polymerase chain reaction was performed to detect a panel of 20 bacterial, viral, and protozoal targets, and we report a high prevalence of enteropathogen carriage, including Shigella spp. or enteroinvasive Escherichia coli in 14%, among a sample of 88 asymptomatic individuals in an internally displaced persons camp in South Sudan. Further studies are needed to determine the contribution of such carriage to the spread of disease.
    • Immune Responses to an Oral Cholera Vaccine in Internally Displaced Persons in South Sudan

      Iyer, AS; Bouhenia, M; Rumunu, J; Abubakar, A; Gruninger, RJ; Pita, J; Lino, RL; Deng, LL; Wamala, JF; Ryan, ET; et al. (Nature Publishing Group, 2016-10-24)
      Despite recent large-scale cholera outbreaks, little is known about the immunogenicity of oral cholera vaccines (OCV) in African populations, particularly among those at highest cholera risk. During a 2015 preemptive OCV campaign among internally displaced persons in South Sudan, a year after a large cholera outbreak, we enrolled 37 young children (1-5 years old), 67 older children (6-17 years old) and 101 adults (≥18 years old), who received two doses of OCV (Shanchol) spaced approximately 3 weeks apart. Cholera-specific antibody responses were determined at days 0, 21 and 35 post-immunization. High baseline vibriocidal titers (>80) were observed in 21% of the participants, suggesting recent cholera exposure or vaccination. Among those with titers ≤80, 90% young children, 73% older children and 72% adults seroconverted (≥4 fold titer rise) after the 1(st) OCV dose; with no additional seroconversion after the 2(nd) dose. Post-vaccination immunological endpoints did not differ across age groups. Our results indicate Shanchol was immunogenic in this vulnerable population and that a single dose alone may be sufficient to achieve similar short-term immunological responses to the currently licensed two-dose regimen. While we found no evidence of differential response by age, further immunologic and epidemiologic studies are needed.
    • Mapping the burden of cholera in sub-Saharan Africa and implications for control: an analysis of data across geographical scales

      Lessler, J; Moore, SM; Luquero, FJ; McKay, HS; Grais, R; Henkens, M; Mengel, M; Dunoyer, J; M'bangombe, M; Lee, EC; et al. (Elsevier, 2018-03-01)
      Cholera remains a persistent health problem in sub-Saharan Africa and worldwide. Cholera can be controlled through appropriate water and sanitation, or by oral cholera vaccination, which provides transient (∼3 years) protection, although vaccine supplies remain scarce. We aimed to map cholera burden in sub-Saharan Africa and assess how geographical targeting could lead to more efficient interventions.
    • Population-Level Effect of Cholera Vaccine on Displaced Populations, South Sudan, 2014

      Azman, AS; Rumunu, J; Abubakar, A; West, H; Ciglenecki, I; Helderman, T; Wamala, JF; Vázquez, OR; Perea, W; Sack, DA; et al. (Center for Disease Control, 2016-06-01)
      Following mass population displacements in South Sudan, preventive cholera vaccination campaigns were conducted in displaced persons camps before a 2014 cholera outbreak. We compare cholera transmission in vaccinated and unvaccinated areas and show vaccination likely halted transmission within vaccinated areas, illustrating the potential for oral cholera vaccine to stop cholera transmission in vulnerable populations.