Introduction
Methods
Event | Definition |
---|---|
Onset | For diseases of which one case constitutes a potential outbreak, the date of onset of symptoms of the primary case. For diseases that are normally endemic but are considered epidemic when an unusual increase in burden is observed, the date on which the outbreak threshold was crossed, according to the authors. If investigation revealed previous undetected outbreaks of the same health event, this was also noted. |
Detection | The date a report of a possible outbreak was sent to the highest appropriate level of authority. This could be the date of initial detection, if no authorities were required to be notified. |
Confirmation | The date on which the aetiologic agent of the outbreak was confirmed. |
Investigation | The date an investigation team arrived to the outbreak-affected community. |
Declaration | The date the outbreak was officially declared as such by health authorities of the country concerned. |
Control | The first day of a reactive vaccination campaign (we only computed the date of this event for diseases for which vaccination was the main control intervention available, since the date of implementation of other control interventions, such as water and sanitation, is difficult to define). |
Results
Search strategy results
Mode of detection of outbreaks
ID | Country, area, date of onset (references) | Aetiologic agent | Onset to detection (days) | Comments |
---|---|---|---|---|
1 | Afghanistan, Kabul, May 2005 [19] |
Vibrio cholerae
| Increased case numbers reported through sentinel surveillance system. A low mortality was attributed to the rapid activation of the surveillance system and a rapid response. | |
2 |
Plasmodium falciparum
| (11) | Médecins Sans Frontières (MSF) initially noticed a doubling of caseloads over the previous week and compared incidence to previous 3 years. The outbreak was not confirmed until seroprevalence tests were performed in week 7 of the epidemic. | |
3 |
Neisseria meningitidis
| Annual peaks of meningococcal meningitis are noted in this region. | ||
4 | Chad, Koumra district, Jan 2001 [24] |
Neisseria meningitidis
| No further details were available. | |
5 | DRC, Kinshasa, Jan 2002 [25] | Measles virus | The outbreak was detected by a sentinel surveillance system. Detection was through both trend analysis and reports from health facilities not included in the system. During the outbreak there were significant delays in reporting from health districts. Limited population movement within the city delayed spread of the epidemic. Early reactive vaccination of unaffected districts could have averted many cases. | |
6 | Hepatatis E virus | The population of Mornay had recently increased due to the arrival of tens of thousands of internally displaced persons. Security concerns and a lack of confidence in Western medicine may have delayed detection. The local hospital became overwhelmed. Cases were reported to the EWARN system. | ||
7 | Sudan, northern Sudan, Oct 2003 [29] | Measles virus | Detection was extremely late, almost once the outbreak was over. The investigation pointed to ongoing underreporting of measles by existing surveillance systems in Sudan. Poor access to health-care facilities may be a strong contributing factor. | |
8 | Sudan, Aweil East county (Southern Sudan), Jun 2003 [20] |
Plasmodium falciparum
| (7) | MSF reported an alert after quadrupling of cases. Historical comparisons were hampered by changes in diagnostic strategies and reduced health care utilisation rates due to flooding. Weekly reporting and analysis, and a free and steady supply of anti-malarials may have favoured early detection. |
9 | Sudan, Abou Shouk camp, North Darfur, Jun 2004 [30] |
Shigella dysenteriae type 1
| 46 | In the early stages of camp administration, there was poor reporting of diseases. An emergency meeting was held to discuss the number of diarrhoea cases being seen in therapeutic feeding centres and at camp clinics. The WHO's EWARN system verified the outbreak. |
10 |
Leishmania donovani
| Recently internally displaced populations had poor access to health care. Cases were carried on stretchers for days to receive treatment. |
ID | Country, area, date of onset (references) | Aetiologic agent | Onset to detection (days) | Comments |
---|---|---|---|---|
11 | Guinea, Dinguiraye prefecture, Oct 2004 [34] | Yellow fever virus | In 2002 an African network of laboratories for the diagnosis of yellow fever was developed, leading to far greater testing of acute jaundice cases. | |
12 | Guinea, Kissidougou district, Jun 2006 [35] | Yellow fever virus | A yellow fever vaccination campaign had been conducted in this district, with reported coverage of 93%. Only one case of yellow fever was identified. Close surveillance was to be maintained but a mass vaccination campaign was not considered necessary. | |
13 | Guinea, Faranah health district, Dec 2008 [36] | Yellow fever virus | 60 | Two cases of yellow fever were initially reported through the yellow fever surveillance system. A further 21 suspected cases were recorded. A targeted mass reactive vaccination campaign was planned. |
14 | Liberia, Feb 2004 [34] | Yellow fever virus | 42 cases of yellow fever were notified from eight of the country's fifteen counties. | |
15 | Myanmar, Yangon, 2001 [37] | Dengue virus | Dengue is endemic in Myanmar. Outbreaks occur cyclically but this outbreak was the largest on record. | |
16 | Ebola virus | (34) | In early January 2003, a WHO team arrived in the area to reactivate surveillance and reinforce hygiene promotion, following detection of a zootic among primates. A human outbreak was notified to the Ministry of Health and WHO 15 days later, 7 days after the index case was admitted to hospital. Control efforts were hampered by difficulties in communication and transport. Difficulties with community acceptance were also reported, including strong cultural objections to the collection of blood and post-mortem skin samples, delaying outbreak confirmation. | |
17 | Sudan, Southern Sudan, 2000 [18] | Viral haemorrhagic fever | (7) | A local team from the southern Sudan EWARN detected and reported the case. Test results were available within 2 weeks of the reported onset. |
18 | Yellow fever virus | A Norwegian NGO reported the suspected outbreak through the Southern Sudan EWARN system. | ||
19 | Sudan, South Kordofan state, Oct 2005 [43] | Yellow fever virus | (30) | A sentinel surveillance system of hospitals and clinics was in place. Jaundice cases were reported promptly by state health officers through the central surveillance system, but yellow fever was not initially considered and the outbreak was initially attributed to dengue. Laboratory investigation was not initially pursued. Confirmation and the start of control occurred more than a month after notification. |
20 | Ebola virus | 21 | Surveillance using haemorrhagic fever case definitions and a rapid response through EWARN contributed to a small number of cases. A concomitant measles outbreak complicated case identification, hampering control measures. On site laboratory facilities could have prevented this. |
ID | Country, area, date of onset (references) | Aetiologic agent | Onset to detection (days) | Comments |
---|---|---|---|---|
21 | Afghanistan, Bamian, Sep 2000 [48] |
Plasmodium falciparum
| * | A United Nations radio operator notified the alert. A similar outbreak had occurred undetected two to three years earlier. |
22 | Afghanistan, Taiwara District, Mar 2002 [49] | Scurvy | (46) | Isolation of the district during the winter months delayed detection. The outbreak was reported by an international NGO. |
23 | Marburg virus | * | Concerns of an unusual severe illness were raised by hospital staff in October 2004. A poliomyelitis surveillance officer carried out the initial case investigation in November. Blood samples were sent for analysis at the CDC. Results were initially negative for any viral haemorrhagic fever. Low numbers of similar cases occurred over subsequent months. By 9 March 2005 the situation worsened, and the first death among health care staff occurred. New blood sampling confirmed Marburg on 21 March 2005. Travel by road was precarious, necessitating air transport. Retrospective analysis identified 102 cases dating back to October 2003. Fear and poor adherence to infection control procedures hampered control. | |
24 | Central African Republic, Bangui, Jul 2002 [59] | Hepatitis E virus | A government chief medical officer reported people with jaundice dying of haemorrhage. Yellow fever was initially suspected. Investigation revealed symptoms suggestive of hepatitis. Laboratory tests confirmed Hepatitis E. | |
25 | Chad, Jun 2005 [60] | Measles virus | A senior vaccination officer with MSF noticed a high incidence of measles being reported from health clinics, during a site visit. A surveillance system was in place, but the data were not being analysed. | |
26 | DRC, Kinshasa, Jun 2003 [61] |
Escherichia coli
| An informal alert was raised by the Institut National de Recherche Biomedicale in Kinshasa in response to an increasing incidence of severe diarrhoea testing positive for E coli. An outbreak investigation could not be conducted at the time due to political unrest. A high case-fatality amongst infants at a city hospital was attributed to insufficient treatment, particularly haemodialysis, at the beginning of the outbreak. | |
27 | DRC, Bosobolo district, Equateur Province, Nov 2002 [62] | Influenza virus | 80 | A local NGO reported the outbreak. The area was under the control of a rebel group. The public had little access to medical facilities. A large proportion of deaths could have been prevented with antibiotics. |
28 | DRC, Orientale Province, Jan 2005 [63] |
Yersinia pestis
| (28) | An informal alert of an epidemic, initially thought to be of haemorrhagic fever, was notified by local health providers in a camp for diamond miners. |
29 | Haiti, Petites Montagnes, 2004 [64] |
Tunga penetrans
| Health care facilities were up to 20 hours' walk away and at times unreachable. Clinical staff became aware of the outbreak relatively late, after receiving news brought by community health workers. | |
30 | Myanmar, Yangon, 2001 [65] |
Gnathostoma spinigerum
| The outbreak occurred amongst Korean immigrants. The alert was raised by the Korean Embassy. | |
31 | Ebola virus | 24 | Red Cross volunteers informed local health authorities of a rumour of four suspicious deaths. A week later, a regional investigation team notified an alert of viral haemorrhagic fever to the central level. Impassable roads delayed the response team's arrival by 4 days. The response team was blamed for people dying and for bringing the disease. There was fear of isolation centres and at-home isolation kits were experimented with. | |
32 | Republic of Congo, Impfondo, Likouala district, Jun 2003 [68] | Monkeypox virus | (65) | A physician treated several patients with pox-like lesions over a period of 3 weeks. Alarmed by the severity of the more recent cases, he sent photographs to colleagues from a city hospital of whom one was invited to assist with diagnosis and control. A week later, the outbreak was reported to the CDC and US embassy. |
33 | Somalia, Afmadow district, Lower Juba Region, Dec 2006 [69] | Rift Valley fever virus | In November 2006, warnings were issued of possible Rift Valley Fever outbreaks, following predictions by spatial models. On 19 December, the WHO received reports of suspected cases in Somalia. Violence, and later also a Kenyan border closure substantially delayed investigation. The virus was laboratory confirmed on 20 January. WHO's outbreak response teams in Nairobi worked closely with poliomyelitis surveillance officers and MSF in Somalia to investigate. Somali medical officers were provided with training on diagnosis and control by the WHO. Security deteriorations further hampered control efforts. | |
34 | Sudan, Nuba mountains, South Kordofan state, 2002 [70] | West Nile virus | MSF operated the only health clinic available in the area, and notified the alert. Cases came from villages up to 8 hours' walk away. | |
35 |
Vibrio cholerae
| Due to collapsing health services, surveillance system completeness was estimated at 30%. The initial recognition of the epidemic was an increased number of cases of 'watery diarrhoea' being noted by Municipal Health Clinics. The ability of the Public Health Laboratory to confirm cholera was greatly limited by shortages of manpower and resources resulting from economic crisis. A second wave of the epidemic from Oct 2008 spread to all provinces and neighbouring countries. The Zimbabwean government declared an epidemic in Dec 2008. |