Tracking Sudan virus in a concrete jungle: cases in Kampala City

¹Uganda Public Health Fellowship Program-Uganda National Institute of Public Health, Kampala, Uganda, ²Division of Global Health Protection, Global Health Center, US Centers for Disease Control and Prevention, Kampala, Uganda

^&Corresponding author
Lilian Bulage, Uganda Public Health Fellowship Program-Uganda National Institute of Public Health, Kampala, Uganda

Case study    

Part I - Ebolavirus in Kampala

On 20^th September 2022, the seventh Ebolavirus outbreak in Uganda was declared after a case of Sudan virus (SUDV) was confirmed in a 26-year-old man living in Mubende District, central Uganda. Over the next nine weeks, the outbreak spread through Mubende District and eight other districts (Figure 1). By the outbreak's end, there were 142 confirmed cases and at least 22 probable cases, most in Mubende and Kassanda districts. Sudan virus causes a deadly viral hemorrhagic fever (VHF) referred to as Sudan virus disease (SVD). The virus reservoir is thought to be bats, unaffected by the virus; however, it can cause disease in humans and nonhuman primates. Sudan virus usually enters the human population during contact between a human and an infected bat or primate. After it enters the human population, infection is transmitted through direct contact with infectious blood, body fluids, and animal tissues of infected persons. Symptoms include fever, abdominal pain, headache, diarrhea, vomiting, generalized body weakness, and sometimes hemorrhage. The incubation period of SVD is approximately 4-17 days (mean 6-7 days) and infected persons usually recover or die within two weeks of onset. Patient caretakers, household members, and healthcare workers who fail to use appropriate personal protective equipment with infected persons are at high risk of infection. Since high levels of virus remain in the body at death, persons who touch or help prepare an SVD patient´s body for burial are also at high risk of infection. Ebolavirus, including SUDV, can spread rapidly in the human population. Persons suspected to have infection must be isolated as soon as they have symptoms, and tested [1]. Case investigations are necessary for every infected person, to identify the source of the patient´s infection and determine who else might be at risk, either from exposure to the patient or from exposure to the same source of infection as the patient.

Question 1: what is a case investigation?

Question 2: based on what you have read up to this point (or what you know from other readings), what are some public health strategies for controlling SUDV (Ebolavirus) spread?

While the outbreak spread substantially in the first two weeks, no cases had been recorded in the capital city of Kampala. On October 8, the Uganda Virus Research Institute notified the National Public Health Emergency Operations Center (PHEOC) about a new patient with confirmed SVD in Kampala. The patient, a 45-year-old male, had traveled from Mubende District to Kampala on October 6 to seek medical care. On October 7, he was admitted to Kiruddu National Referral Hospital (NRH), where he died the next day. Kampala, the financial and economic center of Uganda, is located approximately 150 km from Mubende District. In 2022, the permanent Kampala population was estimated at 1.7 million, with a transient day population reaching 5 million [2]. Approximately 60% of the population lived in informal settlements. Most of the 1,500 health facilities in the city were lower-level health facilities. Besides Kiruddu NRH, the city also had three other referral hospitals: Mulago NRH, Kawempe Referral Hospital, and Naguru Referral Hospital. The city was divided administratively into five divisions, each run semi-independently from each other (Figure 2).

Question 3: how might response need to a SUDV outbreak differ in an urban setting than in a rural setting? Note: please allow five minutes for the class to think through the responses.

In late September 2022, Kampala Capital City Authority (KCCA) staff began mobilizing resources and wrote a preparedness plan in anticipation of the possible spread of the outbreak to the city. There was substantial concern about the impact even a single SVD case could have if it spread to the capital. Before the 2014 West Africa Ebolavirus outbreak, such outbreaks were largely limited to rural areas, where control activities were well-defined. However, once the outbreak in West Africa reached urban centers, it escalated rapidly [3]. Kampala was eager to avoid a similar situation.The most pressing immediate concern for the KCCA team was the movement of the Kampala patient around the city while he was ill. Besides having been treated in a national referral hospital without recognition of his infection, he had also moved extensively around the city to obtain care and might have infected other members of the public inadvertently. On October 8, a team from the Uganda Public Health Fellowship Program was dispatched to Kiruddu NRH to start investigating the case.

The case investigation team included seven field epidemiologists, headed by a team lead. Before going to Kiruddu NRH, the team agreed that they would start every day with a morning debrief, during which the members would share the previous day´s proceedings, including pending work and challenges. This would be followed by drawing up a daily work plan and dividing the work among the team members. For security reasons, at least two epidemiologists would be deployed together on each team, and all investigations would stop at 5 PM. This would also allow sufficient time for the teams to draft case narratives and presentations for the outbreak-related meetings each evening.

Question 4: as a team member, what information would you consider most critical to collect about the case? What sources would you use to collect this information?

Part II - the runner, part A

Over the next two days, the case investigation team gathered information about the case patient at Kiruddu NRH. They used hospital medical records and interviews with the attending doctors, nurses, and morticians to attempt to reconstruct his history from the time he became ill until after he died. The patient, known as C070 (during the response, cases were denoted with a C and sequential numbers), had come from Mubende District. His household and extended family had already lost several members to SVD. Although C070 was a known high-risk contact, he had refused to be monitored and would not leave the house when the contact tracing team visited his home.

Question 5: why might people not want to cooperate with contact tracing teams? What are some strategies that might be used to improve participation?

Ten days earlier, on September 27, the Mubende District contact tracing team had visited the home of C070 in Mubende District but did not find him at home. Other family members shared that he had begun feeling unwell and had left, but they were unwilling to provide information about where he had gone or how he had traveled. During the investigation in October, the Kampala case investigation team learned that from October 2 to October 5, C070 had gone with his wife to a shrine (a traditional healing site used by patients seeking alternative care) in Luweero, seeking healing from his illness. On October 6, he traveled to Kiruddu NRH in a matatu (public minibus). On admission to Kiruddu NRH on October 6, C070 had profuse diarrhea and was vomiting blood. He was diagnosed with gastroenteritis and acute kidney injury. He provided a false name and did not report his family history, nor that he lived in Mubende District. Despite receiving intensive care, he died on October 8. His body was taken to the hospital mortuary for preparation. The prepared body was put in a polyethylene body bag and placed in a wooden coffin.

On October 8, during their monitoring visit to C070´s home, the Mubende contact tracing team was told about his death. They were also told that the family was traveling with his body in a public minibus - with his coffin placed on the roof rack - back to Mubende for burial, about 3 hours away. A burial team went to his home to wait so they could swab the body to test for SVD before burial. That evening, he was buried in a safe and dignified burial, and shortly afterward, his sample tested positive. The investigation team in Kampala quickly began assembling of a list of people to follow up.

Question 6: make a list of the contacts you would want to find for C070. Instructor: suggest that participants make a timeline of C070´s activities and who he was in touch with and identify together the period of interest for his contacts (people he interacted with from his onset until his isolation date)

Part III - the runner, part B

The team made a comprehensive list of contacts of C070 who they wanted to follow up. While some people were easy to find, others were more challenging. The list of contacts they made for C070 is below. List of contacts for C070: i) wife; ii) anyone who might have been in contact with him from the time he left Mubende until he went to the shrine in Luweero; iii) staff and other patients at the Luweero shrine; iv) persons sharing a room or otherwise in contact with him at the hospital; v) attending doctors/nurses at NRRH; vi) matatu driver/co-driver who transported his body; vii) anyone else who might have been in the matatu with him; viii) cleaners at the hospital; ix) cleaners of the matatu; x) laboratory staff who drew his blood sample; xi) mortician who prepared his body at NRRH. Knowing that Ebolavirus patients become more infectious with time and that the bodies of patients who are severely ill with or have died of any Ebolavirus can be extremely infectious, the team prioritized contacts who had been in contact with C070 late in their illness and after death. Among these was the matatu driver who had transported the body from Kampala to Mubende and his wife, who was 28 weeks pregnant and who had taken care of C070 while he was in the hospital. However, the family denied knowing the matatu driver´s name or any information about the matatu.

Question 7: how might you go about finding the patient´s family members or the driver(s) of the minibus?

The family had no records of the matatu used to transport the body of C070. However, the team felt it was critical to reach the driver. Realizing that there were closed-circuit televisions (CCTVs) at the hospital and nearby junctions, the team worked with the hospital and the city and obtained permission to review the footage, and within a few hours were able to identify the matatu that had picked up the body of C070. The team reached out to the taxi (matatu) drivers´ association in Kampala and visited the taxi parks to identify the operator of the matatu. However, the driver was frightened and refused to speak to the team. Three weeks later, when the driver finally agreed to speak with the team by phone, he admitted to transporting the body of C070 in his matatu. However, he reported that neither he nor his co-driver had been ill. He could not recall the passengers who had used the matatu after transporting the body.

Question 8: at this point, would you conduct any further follow-up on the driver and co-driver?

The team also urgently wanted to reach the wife of C070, who they felt was at extremely high risk of infection. Pregnant women who contract Ebolavirus are also at high risk of poor outcomes, including fetal death. However, they did not know where she was. On October 8, the team was able to reach her by phone. She was distressed and did not want to share any information. During October 9-10, the team continued trying to reach her, but she turned her phone off. On October 10, increasingly concerned about her possible infection and the potential for her to transmit it to others, the team decided to use mobile forensics. Mobile forensics is the process of recovering digital evidence from cell phones, tablets, or other mobile devices. Mobile devices contain an abundance of information, including text messages, web search history, and location data. Phone call logs can provide phone numbers, times and dates of calls, people who are called most frequently, and GPS locations of the nearest cell service tower at the time of the call. Call logs can also provide greater context about a person´s social life or business contacts, and indicate when they did not make calls (which might happen during an illness). With the assistance and permission from the Uganda Police Force, on October 10, the team obtained phone logs for C070´s wife. They planned to use the logs to understand her movement history, see if she was still in Kampala, and, if so, where she might be. After receiving the logs, they were able to confirm that until October 8, when her husband died, she had been living in a suburb of Kampala called Nateete.

During October 11-12, the case investigation team, together with the police force, continued to track her phone. On October 12, the wife of C070 switched on her phone again, and the team was able to triangulate the signal to Kitebi Health Center III (HCIII) in Kampala, near Nateete. At Kitebi HCIII, the investigation team found C070´s wife - and her newborn infant - admitted to the observation ward. They learned that she had arrived that same day with abdominal pain, diarrhea, vomiting, and vaginal bleeding. She was accompanied by a female caretaker and appeared to be in pre-term labor. She provided a fake name on admission and did not disclose her history of contact with an SVD patient. Her premature infant was delivered with the assistance of a midwife shortly after her arrival, after which the delivery room was cleaned of blood, diarrhea, and vomitus by the health center cleaner. Due to her illness and the prematurity of the newborn, the health center had decided to hold them both for observation.

The investigation team told the head nurse at Kitebi HCIII that their patient was a high-risk contact with a confirmed SVD patient. Both the wife of C070 and her premature baby were immediately evacuated to Entebbe Grade B Hospital for isolation and management. The midwife, the cleaner, and the caretaker were also isolated at Mulago NRH in a 'holding ward' to see if they developed symptoms. On October 13, while in isolation at Entebbe grade B hospital, the wife of C070 tested positive for SUDV and was denoted as case C077. On October 18, the mortuary attendant at Kiruddu NRH who had prepared the body of her husband, C070, became symptomatic and was confirmed as case C107. Unfortunately, the infant of C077 died a week later in an isolation ward. He tested positive for SVD and was denoted as case C096.

Question 9: identify the strategies used to investigate C070 and his wife. Are the strategies used-acceptable to you? Why or why not?

Part IV - the neighborhood

On October 15, a 33-year-old male farmer from Kassanda District died at Mulago NRH in Kampala and tested positive for SUDV, becoming case C081. Working together with the Kassanda District case investigation team, the Kampala team learned that on October 6, case C081 had been treated in a clinic in Kassanda District for apparent liver and kidney disease. He stayed at the clinic for 3 days. He had been admitted together with a healthcare worker who was himself very ill, and who - unbeknownst to C081 - died just a few days later as a probable case of SVD. On October 12, with a worsening illness, C081 was taken to Kampala in a matatu to access more advanced healthcare. Upon arrival in Kampala, C081 stayed overnight with his extended family in a community called Masanafu. He was welcomed into the community by his brother´s family and a neighboring family, ultimately coming in contact with 11 people in total, including school-aged children. The next morning, on October 13, C081 visited a private clinic near in Kafeero Zone, Mulago NRH (clinic N) for treatment. At clinic N, he was admitted and given intravenous fluids and antipyretics for approximately 12 hours. On discharge, severely ill, he went to the emergency department of Mulago NRH, where he presented with fever, vomiting, headache, diarrhea, and weakness. He was admitted and diagnosed with peptic ulcer disease. Shortly after his admission, he began hemorrhaging from the nose and mouth and was moved to a 'holding´ ward, where samples were taken for SVD testing. On October 15, he died, still in the holding ward. A safe and dignified burial team collected and buried his body.

Question 10: start a timeline of events for C081. Continue to build it as you proceed through the story for C081

Question 11: who would you list for contact tracing in this investigation? Are there any special groups you would prioritize?

The family members in Masanafu and neighbors were all listed as high-risk contacts. The team was especially concerned about the children, who attended three different schools in the area. If the children became ill, they could potentially spread the illness at school.

Question 12: what interventions do you think are appropriate for exposed children who go to school? What are the pros and cons of different interventions?

At this point (October 16), the exposures in Masanafu had started four days earlier (October 12). The last contact between C081 and his family was on October 15, when he died, while the last contact with the neighbors was on October 12. Contacts in both groups were now at risk of becoming overtly ill and spreading the infection to others. The response teams decided to follow up on all the contacts at the two homes in Masanafu. Both families with whom C081 had interacted were asked to stay home for 21 days from the date of their last contact with C081 and report any symptoms. The children were asked to not attend school. At the same time, the teams continued to visit both households each day, during which all the family members denied any symptoms. The World Health Organization recommends laboratory testing for Ebolavirus only if a person develops symptoms. Testing before the onset of symptoms is frequently negative even in a person who is incubating the virus, which can cause a false sense of security that may not be warranted. Although the family members continued to deny symptoms, on October 21, a community member contacted a local health worker and told her that one of the family members had been at a drug shop buying painkillers and antimalarial drugs. Because of this, during the visit to the homes on October 22, the contact tracing team chose to test all ten contacts who were home at the time of the visit.

Question 13: do you agree with the response teams' decision to test the contacts despite their denying signs and symptoms?

Question 14: if you were the team leader, how would you go about the contact listing at the schools?

On October 22, nine of the ten contacts tested positive for SVD, including all 3 school children. All were isolated at Entebbe Regional Referral Hospital on October 23. The family members eventually admitted that they had, in fact, developed symptoms, but were frightened about being confirmed as infected. The investigation team further learned that, against recommendations, two of the three school children had continued going to school during October 17-21. The two affected schools had both day students and boarding (live-in) students. One of the school children who had tested positive, C102, was a 12-year-old grade-6 (P6) day student at a private primary school in Masanafu. Despite developing symptoms on October 19, he attended school until October 21, after which he stayed at home. The team visited the school to identify contacts for C102. They interviewed the school´s management and asked about the interactions between C102 and other children at the school. The team also drew a map illustrating the seating arrangement of the grade 6 class, including where C102 sat (Figure 3).

Question 15: who would you list as a possible contact for C102 from his classroom?

During the interviews with school management, the team learned that C102´s classroom had 52 pupils, including C102. C102 always sat in the same seat and used empty row 2 while entering and exiting the classroom. At the school, different classes had snack and meal breaks at different times to avoid overcrowding in the eating area. Pupils usually interacted during breaks, lunch, and in the evening, almost exclusively with other children in their classes due to the staggered break times. The team listed all 51 pupils, including those who sat near C102 in class, those nearest to empty row 2, close school friends with whom he spent time (two of these were also neighbors at home). In addition, the team listed the four teachers who worked in C102´s classroom and the two school cooks. Starting on October 24, the school was closed for 21 days. All the contacts were monitored for signs and symptoms for the next 21 days; none developed symptoms.

Part V - the healthcare worker

On September 18, a 28-year-old male clinician working at three separate clinics in Kassanda and Mubende districts developed a fever and cough. On September 19, he took sick leave from work and visited his farm in Luweero District, about an hour north of Kampala. On September 22, while in Luweero, his condition worsened, and he returned to one of his clinics in Mubende where he positive for malaria and was given antimalarial drugs. On September 23, he developed diarrhea and abdominal pain but continued with his treatment for malaria.

Question 16: why are healthcare workers in Ebolavirus-affected areas at special risk during an outbreak?

From September 23 to October 5, the healthcare worker intermittently stayed home sick and worked in his clinics when he felt well enough, but his condition continued to deteriorate. On October 5, he developed hiccups, a common late-stage sign of Ebolavirus infection. His work colleagues contacted his uncle, who lived in Nansana, Wakiso District (a district neighboring Kampala). The uncle picked him up on October 7 and brought him home to Nansana. On October 8, in the company of his uncle and brother, he presented to Mulago NRH in Kampala with fever, vomiting blood, and severe chest pain. Unsatisfied with the services, they left the hospital and returned to his uncle´s home using a matatu. Unfortunately, the patient died on arrival in Nansana. A public vigil was held at his uncle´s home on the evening of October 8. Two health workers from a private clinic in Nansana participated in preparing his body. On October 9, he was buried in Ntungamo District in Western Uganda. As SUDV was not suspected, the burial was not supervised and was attended by mourners from several districts.

During the first two weeks of October, four persons who had been treated during late September and early October at the clinics where the clinician worked became confirmed SVD cases. It was only through investigating their cases that the clinics- and the clinicians who worked at them - became suspect. Through the investigation of those four cases, the 28-year-old clinician - who became case P0093 - was identified and investigated (probable cases were denoted with a leading 'P' rather than 'C' during the response). A review of records at his clinics and interviews with clinic staff revealed that, despite being very ill, he continued to care for patients at the clinics where he worked through October 6.

Question 17: when are healthcare workers at risk to others during an Ebolavirus outbreak? What interventions are needed to protect people seeking care, as well as the people providing care?

On October 22, P0093´s uncle (C095) tested positive for SUDV. On October 25, the uncle´s wife (C0123) tested positive. On October 17, the investigation team discovered that on October 15, C095 had developed fever, vomiting, diarrhea, headache, and loss of appetite, and visited a private clinic in central Kampala for care. He continued to work until October 17 despite being symptomatic, using matatus to travel between Kisenyi (an area of Kampala) and Nansana (an area of Wakiso) twice daily.

Part VI - the healer

On November 12, the Uganda Virus Research Institute informed the NPHEOC about a deceased 45-year-old male farmer from Jinja District (neighboring Kampala District) (Figure 4) who had tested positive for SUDV (C161). On November 2, the farmer developed a fever and visited a drug shop near his home in Jinja. From November 8-11, his condition worsened, and he visited three health facilities, including two lower-level facilities and one general hospital in two different districts. On November 11, he died at home in Jinja District. The family informed the Jinja District health officials, who collected a sample the same day. The family proceeded with his burial, unsupervised by public health officials. He was confirmed positive for SUDV on November 12. The Uganda Public Health Fellowship Program deployed a team of epidemiologists to investigate C161. When the team visited the home, it was discovered that C161´s younger brother, a 39-year-old, had died on October 28. The younger brother lived in a slum in Kafeero Zone, near Mulago NRH in Kampala. His body had been taken to the family home in Jinja for burial. On October 20, while at his home in Kampala, the younger brother developed fever, vomiting, diarrhea, general body weakness, abdominal pain, chest pain, and cough. Over the next week, he visited two private clinics in the Mulago village area.

On October 27, the younger brother visited Mulago NRH, but left, unsatisfied with the services. Extremely ill and expecting to die, he asked family members to take him to his family home in Jinja District. Early the next morning, in the company of his niece, wife, and brother-in-law from Kampala, he traveled to Jinja in a privately hired car. On arrival, he developed bleeding and convulsions and was taken to a private clinic, where he was met by C161, who took care of him at the clinic. On October 28, the younger brother died at the private clinic, and he was buried on October 29 near his home in Jinja District. The burial was not supervised and he was not tested for SUDV. The family of C161 told investigators that the younger brother worked as a traditional healer and herbalist. His workplace was located in the Bwaise Village slum area in Kawempe division, Kampala, and shared a compound with a bar that frequently hosted customers from the village. After the story was shared and C161 tested positive, his brother became probable case P162.

Question 18: based on what you know about P162 and the rest of the case patients so far reported in this case study, what do you think were his possible source(s) of infection?

Question 19: outside of his family, who would you consider the most urgent contacts to identify for P162?

The team attempted to find a log of P162´s patients or any information about who he might have treated while he was ill, but they were unable to find any records. Despite intensive follow-up with the neighbors - who were not welcoming to the investigation team - no one else in his neighborhood developed SVD. However, on November 1, P162´s niece, wife, and brother-in-law returned home to the Mulago area in Kampala. His niece became ill and tested positive for SUDV on November 14. Neither his wife nor his brother became ill.

Part VII - the Masaka case

On November 1, the Uganda Virus Research Institute informed the National Public Health Emergency Operations Centre (PHEOC) about a 23-year-old female, housewife, and resident of Kampala who had tested positive for SUDV (C153). A team from the Uganda Public Health Fellowship Program was deployed to investigate C153. C153´s family home was in Masaka District, but she moved to Rubaga Division in Kampala when she married, renting a one-bedroom apartment with her husband. In mid-October 2022, C153 was 3 months pregnant. On October 13, she visited Mulago Hospital for an ultrasound. On October 22, she began feeling ill and traveled to Masaka District to stay with her family. From October 22-29, she stayed alternately with her sister and parents in Masaka, visiting multiple traditional healers and several private clinics for treatment. On October 27, she developed a fever, weakness, and vaginal bleeding, and miscarried the pregnancy. Over the next 4 days, she became increasingly ill, and on October 31, her family took her to two private medical centers, a traditional healer, and eventually to the emergency department at Masaka Regional Referral Hospital, where she was sent to the maternity ward due to her pregnancy. Clinicians suspected that she might have SVD, isolated her, and took a sample for testing. On November 1, she was confirmed as an SVD case and was referred to Entebbe Hospital for isolation at the Ebola Treatment Unit. Unfortunately, she died while in transit. Investigation of C153 was challenging; family and friends denied that she had died of SUDV and were unwilling to provide any information on her history. As a result, all information was collected from medical records. Needing to understand the source of her illness, the team obtained a manifest of her call logs and phone location for the month before her death.

Question 20: the ´exposure window´ for SUDV cases - the period during which they are exposed to SUDV - is approximately 4-17 days before onset. Using your timelines, which of the previously described cases are possible sources of C153´s infection? Justify your answers

Question 21: why is it important to know where and how C153 contracted SUDV?

Phone logs confirmed that C153 had been to the Mulago area on October 13, on the same day as C081. The team mapped the GPS coordinates from the phone logs of both C153 and C081 day by day and overlaid them on a map. The map showed both C153 and C081 in approximately the same location at the same time of day on October 13 (Figure 5). While the map was suggestive of C081 as a possible source of infection for C153, the team still needed additional evidence to conclusively link the two cases. They decided to try to reach the husband of C153. However, he had gone into hiding, and the team did not know his phone number. During November 3-4, the team further reviewed the phone log for C153 and decided to reach out to some of the people she had called most frequently before her death. Only one (Mr B., a restaurant owner in Kikuubo) was willing to talk. Mr B. confirmed that he knew the husband of C153 and shared information about his workplace. On November 4, his workplace colleagues provided the team with his telephone contact. From his phone log records, the team could see that he had made and received calls from a small village in Butambala District. On November 23, the team visited the village and worked together with the local leaders to find C153´s husband. They found him working in a field, where they assured him that they only wanted to find out if he had been ill and ask a few questions about his wife´s illness. He told the team that he had never developed any signs or symptoms of SUDV. However, he also revealed that C153 had visited Clinic N in Mulago on October 13. This is the same day C081 was at clinic N for 12 hours. While the details of their interaction were unknown, genetic sequencing of C081 and C153´s viruses in December 2022 identified C081 as the SVD patient with the closest genetic sequence in the 2022 outbreak to C153.

Part VIII - the carpenter

On October 21, the contact tracing team from Kassanda District informed the Kampala response team about a 38-year-old male carpenter, a resident of Kassanda District who was a high-risk contact of a confirmed SVD case. He had been under monitoring by the contact tracing team since October 14 but had fled from monitoring, and his whereabouts were unknown. Associates in Kassanda told the team that they believed him to be hiding somewhere in Kampala, He was also rumored to have developed symptoms of SUDV. However, he had switched off his phone and his friends and relatives did not know where he was staying. A team from the Uganda Public Health Fellowship Program was deployed to investigate. Phone tracking revealed that the carpenter was in Bulaga Village, Kampala; however, a team deployed to scout the village was unable to find him. The team eventually was able to reach him by phone and, with negotiations, he agreed to meet them. When they met, they found that he had indeed been ill and had been treated in 3 clinics in Kampala and Wakiso districts between October 19 and November 2. Although he was clinically recovered by the time the team met with him, he allowed a sample to be collected. On November 6, he was confirmed positive and denoted as C155.

Question 22: C155, a known contact of an SVD case who had been lost during follow-up, was confirmed positive for SVD but recovered from his illness. Using the information, we know about him, discuss the implication of this long period of loss to follow up on the outbreak response and control: surprisingly (and happily), despite his history of treatment and travel, contact tracing and follow-up identified no additional cases resulting from C155.

Question 23: based on the case investigation narratives for each of the patients above, list the challenges you might anticipate if you were deployed to investigate an Ebolavirus outbreak, such as SUDV, in an urban setting. For each challenge, discuss how you might overcome it

Part VIII

Conclusion     

The 2022 SUDV outbreak, declared over on January 11, 2023, had 142 confirmed cases and 22 probable cases. Fifty-five confirmed cases died, as well as all 22 probable cases. In total, Kampala City registered 18 confirmed cases and two deaths of persons who lived in Kampala. The cases were registered in three out of the five divisions of Kampala. Patients who travelled to Kampala as well as those who lived in Kampala sought care from multiple health facilities and traditional shrines before being detected by the response teams. The case-patients had high mobility within and outside the city and frequently used public transport. Many were uncooperative with public health interventions and did not disclose vital information about their travel and medical histories. These posed challenges to complete case investigations and spurred the team to consider modified approaches to achieve outbreak control.

One of the most salient findings was that despite large numbers of contacts of these cases, comparatively few became ill. Those that did become ill were the ones closest to the case. The R₀ of SUDV during the 2022 outbreak, defined as the average number of secondary infections generated by an infectious person in a fully susceptible population, was found to be 1.25 (95% CI: 1.03-1.51). If R₀ is <1, transmission is expected to fade out, whereas if R₀ >1, the epidemic has the potential to continue; the larger R₀, the more difficult it is to control the epidemic. The rapid end to the epidemic was likely a result of both the interventions and the surprisingly low infectiousness, with an R₀ that was close to 1 to start with. Despite the challenges, only 53 days elapsed between the discovery of the first case in Kampala and the discharge of the last case in Kampala from the Ebola Treatment Unit. This is likely attributed to several things: i) the interventions in Kampala were more aggressive than in many other areas of the country. Because of the concerns of urban spread, public health leadership in Kampala felt that their responses - which could have been viewed as controversial by some - were warranted. Without the use of phone log tracking, CCTV data, and other persistent follow-up, it is possible that some cases might not have been found, and follow-up would have been incomplete; ii) contact tracing and follow-up was 83% in Kampala, higher than anywhere else in the country. The relatively small area over which the response was managed and the reduced number of hard-to-reach areas improved the capacity to conduct contact tracing and follow-up; iii) for unknown reasons, the virus did not spread as well or as rapidly as expected. Sudan virus is known to have a lower reproductive number compared to the Ebola virus (formerly known as Zaire Ebola virus), which was the causative agent of the 2014-2015 West Africa outbreak. Some degree of luck likely played a hand in allowing limited spread from cases who evaded contact for most of their illnesses.

Following the declaration of the end of the outbreak on January 11, 2023, the city reflected on the lessons learned from the outbreak response. A recovery phase response plan was written and implemented. The plan primarily focused on enhanced surveillance-related activities including mortality surveillance, school-based surveillance, transport surveillance, and enhanced infection prevention and control in health facilities. Because many patients had visited multiple private health facilities and traditional healers and had unsupervised burials, the city organized engagements with the association of the private health sector, and cultural and religious leaders, to strengthen partnerships for public health surveillance.

Competing interests     

The authors declare no competing interests.

Authors' contributions     

All the authors have read and agreed to the final manuscript.

Figures     

Figure 1: map of Uganda highlighting the districts affected by the September 2022 Sudan virus disease outbreak

Figure 2: map of Kampala

Figure 3: illustration of the seating arrangement of C102´s classroom

Figure 4: Jinja, Kampala, and Mulago area map

Figure 5: possible place of exposure of C153 from C081 in Mulago area, October, 13^th 2022

References