Contact Tracing Activities During the Ebola Virus Disease Epidemic in Kindia and Faranah, Guinea, 2014 Meredith G
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RESEARCH Contact Tracing Activities during the Ebola Virus Disease Epidemic in Kindia and Faranah, Guinea, 2014 Meredith G. Dixon, Melanie M. Taylor, Jacob Dee, Avi Hakim, Paul Cantey, Travis Lim, Hawa Bah, Sékou Mohamed Camara, Clement B. Ndongmo, Mory Togba, Leonie Yvonne Touré, Pepe Bilivogui, Mohammed Sylla, Michael Kinzer, Fátima Coronado, Jon Eric Tongren, Mahesh Swaminathan, Lise Mandigny, Boubacar Diallo, Thomas Seyler, Marc Rondy, Guénaël Rodier, William A. Perea, Benjamin Dahl The largest recorded Ebola virus disease epidemic began (3). Contact tracing involves locating all persons who have in March 2014; as of July 2015, it continued in 3 principally been exposed to someone infected with Ebola virus (case- affected countries: Guinea, Liberia, and Sierra Leone. Con- patients) or their body fluids and monitoring them daily for trol efforts include contact tracing to expedite identification EVD symptoms during the 3 weeks after the last exposure of the virus in suspect case-patients. We examined contact (4). This tracing permits immediate identification and iso- tracing activities during September 20–December 31, 2014, lation of symptomatic contacts (suspected case-patients). in 2 prefectures of Guinea using national and local data about case-patients and their contacts. Results show less Incomplete contact tracing and delayed time to isolation of than one third of case-patients (28.3% and 31.1%) were suspected case-patients may result in transmission of EVD registered as contacts before case identification; approxi- to others in the community, perpetuating the epidemic. mately two thirds (61.1% and 67.7%) had no registered con- Excluding Conakry, the capital, Guinea is divided into tacts. Time to isolation of suspected case-patients was not 33 prefectures, which are subdivided into >300 subprefec- immediate (median 5 and 3 days for Kindia and Faranah, tures; these divisions are large and smaller administrative respectively), and secondary attack rates varied by rela- governmental units, respectively. Of all Ebola cases na- tionships of persons who had contact with the source case- tionwide, 3.0% and 1.9% have been identified in Kindia patient and the type of case-patient to which a contact was and Faranah (Organisation Mondiale de la Sante, unpub. exposed. More complete contact tracing efforts are needed data), respectively where respective populations are 4.1% to augment control of this epidemic. , and 2.6% of the national population (Institut National de la Statistique, Guinée, unpub. data). At the time of data col- uring March 23, 2014–July 8, 2015, Guinea report- lection, neither prefecture had its own Ebola treatment unit Ded 3,748 Ebola virus disease (EVD) cases and 2,499 (ETU) or laboratory with Ebola virus testing capabilities; EVD-related deaths (1), as part of what is the largest re- suspected case-patients were transported by ambulance to ported EVD epidemic to date (2). Thorough case identifica- the nearest ETU, which was at minimum a 3-hour drive tion and contact tracing are necessary to end this epidemic from either prefecture (Figure 1). We conducted a retro- spective review of case and contact tracing data collected Author affiliations: US Centers for Disease Control and from a convenience sample from 2 Guinea prefectures, Prevention, Atlanta, Georgia, USA (M.G. Dixon, M.M. Taylor, Kindia and Faranah, during the EVD epidemic response J. Dee, A. Hakim, P. Cantey, T. Lim, M. Kinzer, F. Coronado, from September 20 through December 31, 2014. We pro- M. Swaminathan, B. Dahl); World Health Organization, vide descriptive analyses of case and contact tracing for Brazzaville, Congo (H. Bah, S.M. Camara); US Centers for these 2 prefectures to identify gaps in reporting and the Disease Control and Prevention, Lusaka, Zambia yield of contact tracing; we also propose actions for im- (C.B. Ndongmo); Ministry of Health, Guinea (M. Togba, L.Y. Touré, provement of the contact tracing process. P. Bilivogui, M. Sylla); US Centers for Disease Control and Prevention, Kigali, Rwanda (J.E. Tongren); World Health Methods Organization, Geneva, Switzerland (L. Mandigny, B. Diallo, G. Rodier, W.A. Perea); EpiConcept, Paris, France; World Health Case Identification Organization Ebola Response Team, Conakry, Guinea (T. Seyler, EVD cases in Guinea are categorized into 1 of 3 case M. Rondy) definitions modified from World Health Organization recommendations: 1) suspected case (in a living person DOI: http://dx.doi.org/10.3201/eid2111.150684 2022 Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 21, No. 11, November 2015 Contact Tracing During Ebola Epidemic, Guinea, 2014 Figure 1. Ebola virus disease incidence (confirmed cases per 100,000 population), by prefecture, Guinea, 2014. Distances and driving times for the transport of suspect case-patients from Kindia or Faranah to the nearest Ebola treatment unit are shown (red lines). Data sources: Guinea Ministry of Health; Guinea Ministry of Planning; Database of Global Administrative Areas (GADM); Europa. with fever and >3 of these symptoms: headache, anorex- health response and considered to be nonresearch, it was ia, lethargy, aching muscles or joints, difficulty breath- not subject to US Centers for Disease Control and Preven- ing, vomiting, diarrhea, stomach pain, difficulty swal- tion Institutional Review Board review. lowing, hiccups; or with fever and a history of contact with a person with hemorrhagic fever or a dead or sick Contact Identification animal; or with unexplained bleeding); 2) probable case To identify and register contacts of persons infected with (in a deceased person who otherwise met the suspect case EVD, prefecture public health officials and ETU staff in- definition and has an epidemiologic link to a confirmed or terviewed case-patients, their families, and community probable case); or 3) confirmed case (suspected or prob- members and documented resulting information on stan- able case that also has laboratory confirmation) 5( ). Cases dardized contact registration forms (6). A contact is defined are reported by using a standardized case reporting form, as someone at risk for infection with EVD because he or data from which are submitted to the national viral hemor- she has slept in the same household as a confirmed or prob- rhagic fever (VHF) case database. able EVD case-patient, had direct physical contact with the Cases from the 2 prefectures were identified and cross- case-patient during that person’s illness, had direct physi- referenced between the national VHF case database and the cal contact with the body of a case-patient at a funeral or prefecture case database. Demographic information (sex, during burial preparation, touched the body fluids of a case- age) and case classification (confirmed, probable) were patient during illness, touched the case-patient’s clothes abstracted. Because this investigation was part of a public or linens, or is an infant breastfed by the case-patient (6). Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 21, No. 11, November 2015 2023 RESEARCH Demographic data of contacts (name, age, sex, relationship for becoming a secondary case-patient after exposure to a to the presumed source case-patient, and prefecture and case-patient by relationship status or a case-patient by epi- subprefecture of residence) and daily follow-up data (pres- demiologic case classification. We usedχ 2 tests to measure ence or absence of symptoms) were obtained through use associations between categorical variables; specifically, to of standardized contact tracing forms (6), which populated compare attack rates among family members and non–fam- a prefecture contact database. ily members and among contacts to confirmed versus prob- We performed demographic descriptive analyses us- able cases. A p value of ≤0.05 was considered statistically ing nonduplicated contact data; the individual person was significant. Epidemiologic weeks were in accordance with the unit of analysis. We performed other nondemographic those designated by in-country situation reports. descriptive analyses using contact event data; the contact event was the unit of analysis because a single contact Results may have had contact with several case-patients, resulting in several contact events per person. The case and contact Kindia databases may show differing numbers of source cases be- cause contacts in a prefecture might have contacted source Cases case-patients in another prefecture and data quality issues During September 20–December 31, 2014, a total of 90 could exist. The date of isolation was the date a suspected EVD cases were reported in Kindia; 63 (70%) were con- case-patient was transported to an ETU. We created the firmed and 27 (30%) probable cases (Table 1). The me- following definitions: time to isolation (days) was calcu- dian case-patient age was 35 (interquartile range [IQR] lated by subtracting the date of first symptom onset from 20–50) years; 21 (23.3%) case-patients were <18 years of the date of isolation; family/household member was any- age, and 52 (57.8%) were female. No case-patients were one related by blood or marriage or who lived in the same health care workers. Case-patients resided permanently in household as the case-patient or was described as being a 23 villages in 7 subprefectures of Kindia. Median time caregiver, excluding health care workers; safe burial was a to isolation for suspect case-patients was 5 (IQR 3–7) burial with placement of the body in an impermeable bag days; this time varied by epidemiologic week. Seventy- and interment by a team wearing personal protective equip- one (78.9%) case-patients died; of those, 35 (49.1%) died ment (7). Secondary attack rate was calculated as the pro- in the community, of whom 30 (85.7%) underwent un- portion of new cases among contact events × 100 (8). Be- safe burial. The number of community deaths per epide- cause variables had nonparametric distributions, medians miologic week fluctuated (range 1–7) and peaked during were analyzed. Relative risks were used to quantify the risk weeks 49 and 51 (Figure 2).