| Assab, Awash, Blue Nile, Illubor, & Ogaden regions, Ethiopia1
|
1961/62 |
Asymptomatic individuals from area not affected by ongoing Yellow Fever epidemic |
C |
178 |
42 |
EBOV 24% |
IFA(w) |
≥1:16 |
Antigens: Polyvalent ELM (Ebola-Lassa-Marburg viruses) & monovalent EBOV (Mayinga): all sera reacting with ELM also reacted with monovalent EBOV antigen but not with monovalent Marburg and Lassa. |
Samples from symptomatic Yellow Fever-negative individuals also tested: 12% positive. |
| N.W. Zaire (now Democratic Republic of Congo DRC)2
|
1972–78 |
General population from area west of Yambuku (site of 1st recorded outbreak in 1976) |
C |
251 |
4326 |
EBOV 17.1%10.4% |
IFA(w) |
≥1:16≥1:64 |
Antigen: EBOV (May. 80826) |
|
| Harbel, Bong town, Yekepa, Liberia3
|
1973 |
Staff & family members of rubber and mining companies |
C |
592 |
83 |
Ebolavirus 14.0% |
ELISA/WB |
Not stated |
Antigen not stated |
Sera taken in 1973 and investigated for Lassa and ebolavirus in ~1986. Ebola statistic reported without further information. |
| Northern Rhodesia (now Zimbabwe)4
|
1975 |
‘Control group’ |
C |
243 |
20 |
EBOV 0.8%0.0% |
IFA(w) |
≥1:8≥1:64 |
Antigen not specified in report: Kuhn52 notes antigen as EBOV |
Areas sampled had no known outbreak |
| Yambuku, Zaire (DRC)5
|
1976 |
Asymptomatic contacts of cases |
A |
404 |
10 |
EBOV 2.5% |
IFA(w) |
≥1:64 |
Antigen: EBOVValidation: Repeat testing of the 4 antibody positive with no known contact gave the same results. 32/33 (97%) positive samples (including samples from cases) confirmed positive by CDC (US)4 (p141) |
|
| Residents from villages with cases but no known contact |
B |
448 |
4 |
EBOV 0.9 |
| Residents from 4 neighbouring villages with no cases |
C |
442 |
5 |
EBOV 1.1% |
| Maridi, Sudan (now South Sudan)6
|
1976 |
Close family contacts |
A |
93 |
13 |
SUDV 14.0% |
IFA(w) |
≥1:8 |
Antigen: SUDVValidation: 42 of 48 clinically diagnosed survivors from Nzara (87%) were considered positive using the same IFA protocol. Several samples from Nzara were retested and confirmed positive by CDC (US) using the same protocol. |
9 antibody positive family contacts had symptoms and have been excluded from these figures. Not clear if all subjects in this group were interviewed about symptoms. |
| Asymptomatic Maridi schoolboys with no known contact |
B |
29 |
3 |
SUDV 10.3% |
|
| Asymptomatic hospital staff with probable/possible contact |
A |
64 |
7 |
SUDV 10.9% |
4 nurses; 1 cleaner, 1 toilet cleaner, 1 water carrier were positive |
| Nzara, Sudan (now South Sudan)6
|
1976 |
Asymptomatic cotton factory workers (site of index case but reportedly no direct contact) |
B |
109 |
7 |
SUDV 6.4% |
IFA(w) |
≥1:8 |
|
Among factory workers titre range was 1:16–1:32 |
| Close family contacts of clinically diagnosed cases |
A |
78 |
1 |
SUDV 1.3% |
Only 6/31 (19.4%) of clinically diagnosed subjects were antibody positive, and none had levels>1:32 |
| San Blas Islands, Panama4
|
1977 |
San Blas Indians |
C |
200 |
1 |
EBOV 0.5% |
IFA(w) |
≥1:64 |
Antigen: not specified in report: Kuhn52 records antigen as EBOV |
Areas sampled had no known outbreak. Method of selection not known |
| Tandala, Zaire (DRC)7
|
1977–78 |
Missionaries and ‘a few’ hospital staff with case contact (1977) |
A |
50 |
0 |
EBOV 0% |
IFA(w) |
≥1:16 |
Antigen: EBOV |
One doctor, who tested positive in 1977 and 1978 and had history of severe illness after attending the autopsy of a haemorrhagic fever victim in 1972, is excluded. Some individuals gave samples in both the 1977 and 1978 groups |
| Hospital staff with case contact (1978) |
A |
71 |
0 |
EBOV 0% |
| Residents of villages with confirmed /suspect cases |
B |
346 |
21 |
EBOV 6.1% |
| Residents of other villages in same area |
B |
750 |
58 |
EBOV 7.7% |
| Liberia 8
|
1978-79 |
Random rural general population in multiple counties |
C |
433 |
26 |
Ebolavirus 6.0% |
IFA(w) |
≥1:16 |
Antigens: unspecified ebolavirus, Marburg & Lassa viruses. No sera positive for ebolavirus was positive for MARV or LASV. |
No known outbreak. Titre range: 1:16 to 1:1024 |
| Nzara/Yambio, (South) Sudan9
|
1979 |
Asymptomatic adult family members of cases with known physical contact |
A |
38 |
12 |
Ebolavirus 32% |
IFA(w) |
≥1:16 |
Antigen: unspecified |
|
| Asymptomatic adult family members of cases who denied physical contact |
B |
23 |
3 |
Ebolavirus 13% |
|
| Adults from families without known cases in same area |
B |
45 |
8 |
Ebolavirus 18% |
Unknown if these people were exposed in 1976 outbreak, which could explain the high prevalence |
| Bangassou, Central African Republic (CAR)10
|
1979 |
General population in forest and semi-forest zones |
C |
499 |
103 |
Ebolavirus 2.0%0.6% |
IFA(w) |
≥1:16≥1:64 |
Antigen: Polyvalent of unspecified ebolavirus, MARV & LASV, followed by monovalent test for positive samples. Positive sera sent to CDC (US) for repeat testing; results not reported. |
Areas sampled had no known outbreak |
| Moloundou, Lolodorf Bipindi, Lomie, Yaounde & Pete, Cameroon11
|
1980 |
General population in five regions (forest, pre Sahelian savannah and the capital) and different ethnic groups |
C |
1517 |
147 |
Ebolavirus 9.7% |
IFA(w) |
≥1:16 |
Antigens: unspecified ebolavirus provided by CDC (US) |
No known outbreak. Positives in all areas, range 3%-23%. Highest in Pygmies and rain forest farmers. 6% in the capital, Yaoundé. Report to OCEAC in the same year gave positivity of 6.2% (51/821) in Moloundou, compared to 13.2% for the same location in this study, and 29% (20/70) in Mbatika, but positivity threshold used is not reported.63
|
| Lugulu, western Kenya12
|
1980 |
Family and close neighbours of an IFA confirmed case (asymptomatic?) |
A |
84 |
4 |
Ebolavirus 4.8% |
IFA (?) |
≥1:16 |
Antigens: monospecific, triple (unspecified ebolavirus, MARV, LASV) and poly-antigen (CCHFV, RVFV, ebolavirus, LASV, MARV).Validation: sera examined at National Institute of Virology, Johannesburg and CDC(US): labs used different thresholds, so positive confirmed only where both found ≥1:16 |
Area in Western Kenya, close to Nzoia. Samples collected during investigation of 2 MARV suspect cases who were later shown to be ebolavirus positive. |
| Kenya13
|
1980 |
Different studies in 5 regions of Kenya:—Lodwar, Laisamis, Masia, Malindi/Kilifi- Nzoia |
C |
1058841 |
189 |
EBOV/SUDV 1.7%1.1% |
IFA(w) |
≥1:16 |
Antigens: inactivated unspecified ebolavirus, MARV, CCHFV, RVFV, & LASV; positives tested against EBOV(May) & SUDV (Boniface & Maleo). Authors report ‘most’ of the Nzoia samples were only tested against EBOV(May) |
No known outbreak but Nzoia cohort reported to include suspected cases and their contacts. Highest prevalence: Lodwar 7.8% (north-west Kenya). Note referenced paper includes some sera reported on in other papers.72
|
| Haute Ogooue, Gabon14
|
1980 |
General population in outbreak area but no known contact |
B |
253 |
16851218 |
EBOV 6.3%3.2%SUDV 2.0%0.4%EBOV/SUDV 8.3%3.1% |
IFA(w) |
≥1:16≥1:64≥1:16≥1:64≥1:16≥1:64 |
Antigens: inactivated polyvalent unspecified ebolavirus/LASV MARV: positives tested against EBOV(802850) & SUDV(802681). |
Samples from the Occupational Health Services, plus 28 women & their newborns. One sample was positive ≥1:64 on both EBOV & SUDV |
| Northern Rhodesia (now Zimbabwe)15
|
1980 |
Asymptomatic schoolboys (8-10y): no known outbreak |
C |
486 |
94 |
EBOV 1.9%0.8% |
IFA(g) |
≥1:8≥1:128 |
Antigen: polyvalent CCHFV, RVFV, LASV, MARV, unspecified ebolavirus slides provided by CDC (US): positives tested against individual antigens (EBOV & SUDV)Validation: 4 of 5 positive samples sent to CDC (US) were ≥1:128 in repeat IFA testing. |
None were positive for SUDV. |
| Pool, Congo-Brazzaville (now Republic of Congo)16
|
1981 |
Children from 20 villages aged 3-15 years and unvaccinated for smallpox |
C |
790 |
119 |
Ebolavirus 15.0% |
IFA(?) |
Not stated |
Antigen: polyvalent CCHFV, RVFV, LASV, MARV, unspecified ebolavirus; also tested against monovalent antigens |
Pool region is on the border with DRC. Areas sampled had no known outbreak but populations were selected for close contact with animals |
| Grand Bassa, Liberia17
|
1981-82 |
Individuals asymptomatic for EVD consisting of 106 epilepsy patients; 87 healthy relatives of these patients; 32 unrelated geographically matched controls. |
C |
225 |
26429 |
EBOV 11.6%SUDV 1.8%Overall 12.9% |
IFA(w) |
unclear |
Antigen: polyvalent CCHFV, RVFV, LASV, MARV, EBOV (May), SUDV(Bon) (known as CRE2LM); positives retested against individual antigens.Validation: Difficulties with non-specific binding led researchers to replicate and use blinded observers to read results. Only samples with unequivocally positive results by 2 observers were considered positive. |
No known outbreak. Similar proportion positive in each participant group. 38% epilepsy patients had a febrile illness 1-4 weeks before onset of epilepsy, but no significant difference in seroprevalence with & without febrile history. Paper says 30 positives in total but one counted twice (positive for EBOV and SUDV). Titres ranged from 32-128 for EBOV; 6/29 had antibodies to more than 1 virus. |
| Sud-Ubangi sub-region, DRC (includes Tandala)18
|
1981-85 |
Age/sex matched controls from the same villages as reported cases |
C |
137 |
2 |
Ebolavirus 1.5% |
IFA(w) |
≥1:64 |
Antigen: polyvalent CRE2LM; positives tested against unspecified ebolavirus-specific antigens. |
In addition 188 contacts of possible and probable cases were tested; 28 were positive at ≥1:64 but all had had symptoms fitting the definition of a possible or clinical case. It is not clear how many of the other contacts had symptoms. |
| Northeastern, southeastern & western Gabon19
|
1981-1997 |
Six rural communities (Makokou, Doussala, Doussieousou, Matadi-Ngoussa, Moukoro, Latoursville): sera gathered during onchocerciasis research |
C |
1147 |
14 |
EBOV 1.2% |
ELISA (k) |
Mean +3SD of OD of negative controls |
Antigen: EBOVValidation: In 2003, 6 of original 14 positives were re-bled (others unavailable): 2 were still positive. 14 controls (relatives and ‘cohorts’) were unreactive |
6 seropositives were from north-eastern Gabon where outbreaks had occurred; 8 were from western communities more than 500km from known epidemics. Authors also investigate and correlate animal with human outbreaks. Conclude that less virulent strains of EBOV affected western areas. |
| Madina-Ula, Guinea20
|
1982-83 |
Healthy adults sampled during an outbreak of an unknown disease |
C |
138 |
1142 |
EBOV 7.8%2.9%2.2% |
ELISA(r)ELISA(r)IFA(b)ELISA(r)IFA (b) |
≥1:8≥1:512≥1:16≥1:512≥1:64 |
Antigen: EBOV |
Areas sampled had no known outbreak |
| Benin21
|
1983 |
General population, non-outbreak country |
C |
603 |
2 |
EBOV or SUDV? 0.3% |
IFA (?) |
≥1:64 |
Antigen: EBOV, SUDV |
Unpublished data cited by Gonzalez et al (2005): no further information, not specified which ebolavirus antigen samples were reactive to. |
| Ethiopia, Awash valley1
|
1983 |
Unexposed children |
C |
250 |
0 |
EBOV 0.0% |
IFA(w) |
≥1:16 |
Antigens: Polyvalent ELM (Ebola-Lassa-Marburg viruses) & monovalent EBOV (May) |
Areas sampled had no known outbreak |
| Karamoja, Uganda22
|
1984 |
‘Healthy’ adults 20-40y recruited during visits to a health centre, excluding any with current or recent fever |
C |
132 |
44 |
EBOV 3.0%SUDV 3.0% |
IFA(w) |
unclear |
Antigen: polyvalent CCHFV, RVFV, LASV, MARV, EBOV (May), SUDV(Bon) (CRE2LM); positives retested against individual antigens. |
No known outbreak. Not clear if some samples had antibodies to both EBOV & SUDV. Not specified how many>1:64. All samples<1: 128. |
| Mobai, Sierra Leone & unspecified location Sudan23
|
<1984 |
No information on population type: general population assumed from description- Mobai, Sierra Leone- Sudan |
C |
556284 |
101010 |
EBOV (a) 1.8%(b) 1.8%(a) 0.35(b) 0 |
(a) ELISA +ve/IFA+ve (b) ELISA +ve/IFA −ve or unclear |
ELISA: +ve within 2SD of +ve ref. sera; −ve within 1SD of negative ref seraIFA≥1:100 |
Antigen: EBOVValidation: All? samples were tested using both assays |
Year of sample collection is not recorded. Paper reports a high level of cross reactivity with MARV, lasting a number a number of years after infection. |
| Haute Ogooue, Gabon24
|
1985 |
Inhabitants of Ambinda village |
C |
213 |
20621227 |
EBOV 9.4%1.4%SUDV 0.9%0.5%Overall 10.3%3.3% |
IFA (j) |
≥1:16≥1:64≥1:16≥1:64≥1:16≥1:64 |
Antigen: polyvalent CCHFV (IB-AR-10200 Nigeria), RVFV (ZH-501 Egypt), LASV (Josiah), MARV (Musoki), EBOV (May), SUDV(Bon) (CRE2LM); positives retested against individual antigens. |
No known outbreak |
| Nola,Ikaumba, Bozo, Bangassou, Mbre & Birao, Central African Republic 25
|
1984-85 |
General population from 5 ecological regions including one close to Zaire/DRC outbreak area |
C |
836 |
15263 |
EBOV 18.2%SUDV 7.5% |
IFA(j) |
≥1:16 |
Antigens: EBOV (May), SUDV (Bon), MARV (Mus) |
No known outbreak but Zemio which borders DRC accounted for 43% of EBOV positives |
| Nola,Ikaumba, Bozo, Bangassou, Mbre & Birao, Central African Republic 26
|
1984-85 |
Asymptomatic general population from 5 ecological distinct zones selected on accessibility: additional villages wer chosen where multiple ethnic groups coexisted. |
C |
4295*4078* |
681209853259914335 |
EBOV15.9%5.1%SUDV 19.8%6.4%Overall 21.3%8.2% |
IFA (j) |
≥1:16≥1:128≥1:16≥1:128≥1:16≥1:128 |
Antigens: polyvalent EBOV (May), SUDV (Bon), MARV (Mus), LASV (Jos), CCHFV (10200), RVFV(ZH501); positives (≥1:16) retested against monovalent antigen.Validation: 185 samples were reanalysed by ELISA in 1996: results confirmed original analysis.21
|
Study linked to one above in CAR25 but using different set of sera sampled in the same period.* Two different denominators are cited: 4296 people are reported for all titre levels; 4078 people are reported in the table describing only samples showing titres≥1:128.Highest prevalence in woods and forest regions. 86% of titres≥1:64 but reached as high as 1:2048 |
| Nkongsamba, Cameroon27
|
1985 |
Randomly selected urban general population (15-44 years) |
C |
375 |
75 |
Ebolavirus 1.9%1.3% |
IFA (?) |
≥1:16≥1:64 |
Antigens: polyvalent unspecified ebolavirus, CCHRV, RVFV, MARV) |
These samples were included in the following multi-country study which used a different threshold.28 One sample was positive for both ebolavirus and RVFV |
| Central Africa28 (now Middle Africa) |
1985-87 |
Randomly selected sera collected in:Cameroon (Mora, Maroua, Nkongsamba)Central African Republic (Bangui)Chad (N’djamena)Republic of Congo (Pointe Noire, Brazzaville)Equatorial Guinea (Bioco Island, Nsork)Gabon (Libreville, Port-Gentil, Ogooue-Ivindo, Haut Ogooue, Ngounie) |
C |
11523273347286881841 |
8910733451111259 |
EBOV/SUDVλ7.7%32.7%3.6%7.0%16.1%14.0% |
IFA (w) |
≥1:16 |
Antigens: polyvalent EBOV (May), SUDV (Bon), MARV (Mus), LASV (Jos), CCHFV (10200), RVFV(ZH501); positives (≥1:16) retested against monovalent antigen. |
Areas sampled had no known outbreak |
| Chobe, Northern Botswana29
|
1984-86 |
1984: 52 asymptomatic villagers)1985: 25 villagers with non-specific or ictero-haemorrhagic symptoms1986: 77 asymptomatic villagers |
C |
154 |
0 |
EBOV/SUDV 0% |
IFA (J) |
≥1:16 |
Antigens: polyvalent CCHFV, RVFV, LASV, MARV, EBOV (May), SUDV(Bon): positives re-tested against monovalent antigens. |
Areas sampled had no known outbreak. Unable to separate results for the symptomatic group. Only reaction found was against RVFV. Testing performed in Paris. |
| Lobaye, Central African Republic30
|
1987 |
Asymptomatic general population, Lobaye district: Pygmy hunter-gathers |
C |
127 |
31 |
EBOV/SUDV 24.4% |
IFA (J) |
≥1:128 |
Antigens: polyvalent EBOV (May), SUDV (Bon), MARV (Mus), LASV (Jos), CCHFV (10200), RVFV(ZH501); positives (≥1:16) retested against monovalent antigen, considered reactive if≥1:128.Validation: 296 samples from this study and 185 samples from the CAR 1984-85 study above were re-analysed in 1996 using ELISA (≥1:400 & sum of 4 ODs≥1.000). 6.2% were Ebola IgG positive (30/481) compared to 6.4% in these samples previously by IFA.21,26
|
Area with no known outbreak.Of the positives, 45 reacted to both EBOV & SUDV: it is not possible to identify how this splits between the groups. |
| Asymptomatic general population Lobaye district: Mozombo/Mbati subsistence farmers |
C |
300 |
42 |
EBOV/SUDV 14.4% |
| Nigeria31
|
1988 |
Asymptomatic general population in different locations |
C |
1677 |
3022 |
SUDV 1.8%EBOV/SUDV 1.3% |
IFA(w) |
≥1:10 |
Antigens: polyvalent CCHFV, RVFV, LASV, MARV, EBOV (May), SUDV(Bon): positives with titre≥1:10 retested against monovalent antigens. Known positive/negative controls used |
Areas sampled had no known outbreak. All positive samples came from savannah areas (Benue/Gongola)Of the positives, none reacted to EBOV alone. |
| Antanarivo, Mandoto, andasibe, Tsiroanomandidy & Ampijoroa, Madagascar32
|
1989 |
Asymptomatic adults from 5 different areas (urban & rural, cattle-lands, forested) |
C |
381 |
17 |
EBOV 4.5% |
IFA (j) |
≥1:16 |
Antigens: polyvalent CCHFV, RVFV, LASV, MARV, EBOV (May), SUDV(Bon): positives retested against monovalent antigens |
Areas sampled had no known outbreak. Range of titres: 1:16 to 1:512; highest prevalence in the capital Antanarivo 13.3%. |
| United States33
|
1990 |
CDC (US) employees with current or previous occupational exposure to monkeys. None ill. |
B |
550 |
42 |
EBOV/SUDV/RESTV/MARV 7.6% |
IFA (?) |
≥1:16 |
Antigens: EBOV, SUDV, Reston ebolavirus (RESTV), MARV.Validation: confirmed by western Blot |
This paper summarises 2 others 73,74Results are for positivity to at least one of the four antigens, which include Marburg. |
| Adult primary care outpatients in US |
C |
449 |
12 |
2.7% |
| Germany34
|
1991 |
Various groups of healthy individuals, blood donors and routine diagnostic samples, plus 56 individuals who had had contact with Marburg patients in 1972. |
C |
1288 |
1144 |
EBOV 0.85%RESTV 3.4% |
ELISAIFA or WB |
ELISA: 1:100IFA: 1:40WB: +ve if stained≥2 viral proteins) |
Antigens: EBOV (May), RESTV, Marv(Mus)Validation: Considered positive if ELISA confirmed by IFA or WB.Confirmation: ELISA vs IFA 75%; ELISA vs Western Blot 77%. |
Authors state that the sample groups showed no significant differences in the prevalence of antibody against the 3 filoviruses and so they treated as one group for analysis and only overall results reported.WB results: ‘most’ sera reacted with the NP protein, ‘less’ with VP40, VP35 & VP30, and ‘few’ with VP24. None reacted to GP or L proteins. |
| Kikwit, DRC35
|
1995 |
Four forest site populations near Kikwit town, site of outbreak |
B |
230 |
5 |
EBOV 2.2% |
ELISA (k) |
≥1:400 & OD sum≥1.25 |
Antigen: unspecified but Kuhn52 reports EBOV; sera tested in CDC (US) Special Pathogens Lab. |
Differentiation between forest and city workers was difficult: publicity brought people out of their areas: self identified occupations. 95% of participants including all 9 positives said they knew someone with Ebola. |
| City workers, Kikwit |
B |
184 |
4 |
EBOV 2.2% |
| Asymptomatic volunteers from unaffected villages near Kikwit |
C |
161 |
15 |
EBOV 9.3% |
5/15 positives knew someone who had had Ebola |
| Kikwit, DRC36
|
1995 |
Household contacts aged 3 m-58y |
A |
101 |
4 |
Ebolavirus 4.0% |
ELISA (k) |
≥1:400 & OD sum≥1.25 |
Antigen: unspecified but probably EBOV; sera tested in CDC (US) Special Pathogens Lab. |
Paper cites 5 positive sera but 1 miscarried 3 days before giving her positive specimen so fits case definition for Ebola. One of the remaining 4 may have acquired Ebola by sexual transmission from a convalescent. Out of 81 sero-negative household contacts, 15 had episodes of illness fitting case definition at some point during follow-up. |
| Central African Republic 37
|
1992-97 |
Pygmy general population: southern regions of CAR (Lobaye, Belemboke) |
C |
684 |
48 |
EBOV 7.0% |
ELISA (n) |
≥1: 400 |
Antigens: EBOV, MARV, RVFV, LASV, Yellow fever (YF) Hantaviruses (Seoul, Puumala and Thottapalayam)Validation: 244 sera taken in Lobaye in 1995 (11.6% ELISA positive to EBOV) were retested with IFA to EBOV (May) & SUDV (Bon): 34% were positive. |
Prevalence of EBOV seropositivity varied between 2% and 13% in different participant groups. |
| Bantu villagers: southern region of CAR (Lobaye, Belemboke, Nola, Bangassou) |
C |
860 |
44 |
EBOV 5.1% |
| Central African Republic38
|
1992-95 |
Pygmy subgroup (Lobaye, Belemboke: all sites no known outbreaks) |
C |
683 |
48 |
EBOV 7.0% |
ELISA (k) |
Mean+2SD of negative controls ≥1:400 & OD sum of 4 dilutions>1.0 |
Antigens: EBOV (May) Marv(Mus); tests performed by Institut Pasteur, Bangui.Validation: 14 positive & 54 negative samples sent to CDC (US) to be tested against strain antigens: all results confirmed. |
Primary or secondary forest areas with some agricultural activities |
| Non-pygmy subgroup (Lobaye, Belemboke, Bangassou, Nola: all sites no known outbreaks) |
C |
648 |
23 |
EBOV 3.5% |
| Ogooue Ivindo, Gabon39
|
1995-96 |
Residents of 3 encampments (Andock, Minkebe, Mekoua) in the area where the epidemic occurred (including some contacts) |
B |
236 |
23 |
EBOV/SUDV/RESTV 9.7% |
ELISA (k) |
mean+3SD of negative controls |
Antigens: EBOV, SUDV, RESTV with known positive/negative controls |
1 positive serum from a survivor excluded from encampment group; unclear how many known case contacts are included in this group. |
| Residents of 3 outbreak villages (Mayibout 1 & 2, Mvadi) where cases were reported during the outbreak |
B |
205 |
34 |
EBOV/SUDV/RESTV 16.6% |
| Kikwit40
|
1995 |
Healthcare workers in outbreak area (70% hospital; 30% health centre) who did not have known EVD |
B |
400 |
8 |
EBOV 2.0% |
ELISA (k) |
Sum of adjusted OD >1.25 |
Antigen: EBOV |
The 8 positives were from a group of 12 samples which were ‘borderline positive’ on 1st test. Only 4 of these samples were retested: all were negative and have been excluded.129 of the 402 subjects reported being ill during Ebola period. Two with fever and haemorrhage (tested EBOV negative) have been excluded. |
| Gabon 41
|
1996 |
Selected asymptomatic family members directly exposed to body fluids during outbreaks in 1996 |
A |
24 |
11 |
EBOV 45.9% |
ELISA (k) |
Mean adjusted OD for 10 control samples |
Antigen: EBOVValidation: confirmed with western blot on NP and VP40 proteins |
Subjects were asymptomatic throughout and were sampled several times. 1st samples showed no antibodies suggesting no prior immunity; IgG appeared 15-18 days after first possible exposure.Paper also describes results of viral RNA detection after 2 rounds of RT-PCR, finding positive results in 7/11 antibody-positive individuals tested and 0/13 antibody-negative individuals. |
| Nouna River, Ogooue-Ivindo, Gabon42
|
1996 |
Residents in gold-mining villages with contact exposure in 1995 epidemic |
A |
56 |
12 |
EBOV 21.4% |
ELISA (?) |
OD>mean +2SD of 3 known negative controls |
Antigen: ebolavirus Gabon 95-39/3 (Centre International de Recherches Medicales de Franceville) |
All subjects reported fever and diarrhoea at least once in 1-year period of study, but not haemorrhagic symptoms. IgG positive titre range (OD 310-2,666).Age, sex, ethnic group not associated with seropositivity. Non- significant difference in seropositivity in people on site during 1995 epidemic (8.2%) and not on site (3.7%), among those with no reported contact |
| Residents in same villages without contact exposure |
B |
180 |
12 |
EBOV 6.7% |
| Upper Ivindo River, Ogooue-Ivindo, Gabon43
|
1997 |
Individuals from 8 permanent villages in outbreak-prone region (4 survivors excluded) |
B |
975 |
10 |
EBOV 1.0% |
ELISA (k) |
Mean OD negative controls +3SD |
Antigen: EBOV, performed in National Institute for Communicable Diseases South Africa.Validation: All positives plus a random selection of 28 negatives were retested with same protocol in CDC (US)—all were confirmed with response mainly directed to NP, VP40, VP35 and sGP viral proteins. |
Serosurvey done in 1997; questionnaires done in 1999 on 10 positives: only 1 had contact, none were ill. |
| Belarus & Ukraine44
|
1997 |
‘Foreign visitors’ mostly from Africa: unclear if any had history of EVD symptoms |
C |
562 |
30 |
EBOV 5.3% |
IFA (w) |
Not specified |
Antigens: EBOV (May), MARV (Voege) LASV (Jos) |
Authors suggest positive results among foreign visitors reflect historic infection/ recovered cases, and unexpected results reflect cross-reactivity with infections such as malaria, HIV and influenza. Other observers suggest the results are just as likely to be artifact.63
|
| Belarus/Ukraine residents ‘at risk of HIV’ |
C |
506 |
20 |
EBOV 4.0% |
| Blood donors from the Blood Transfusion Institute, MoH Belarus & workers at the Belorussian Scientific Research Institute of Epidemiology & Microbiology |
C |
131 |
21 |
EBOV 16.0% |
| Watsa region, DRC45
|
2002 |
Efe tribe pygmies exposed to a possible case at some time in their lives in household, occupation or funeral setting; no history of haemorrhagic fever symptoms |
A |
38 |
4 |
EBOV10.5% |
ELISA (k) |
2×mean +3SD of negative controls value |
Antigen: EBOVODs were expressed as percent positivity of a confirmed EBOV-positive sample; negative controls were from 60 South African subjects ‘almost certain’ to be seronegative. |
A total of 300 people were sampled from 39 communities. 137 who reported experiencing haemorrhagic fever symptoms sometime in their life are excluded from this summary. 22% of those reporting symptoms were IgG positive. |
| Efe pygmies no reported exposure to possible cases; no history of haemorrhagic fever symptoms |
C |
125 |
22 |
EBOV 17.6% |
| Gabon46
|
2005-08 |
Random sample of asymptomatic people aged >16 years without exposure, over all 9 provinces of Gabon |
C |
4349 |
667 |
EBOV 15.3% |
ELISA (k) & WB |
Cut-off based on negative controls from a French population |
Antigen: EBOV Validation: Random sample of 138 positives were tested by western blot in 2008 and all were positive to at least one EBOV antigen.53
|
Gabon experienced 7 outbreaks between 1994 & 2002 affecting >20 villages and towns; in total there were 208 cases and 151 deaths. |
| Random sample of asymptomatic children from 6 villages in outbreak-prone province (Ogooue-Ivindo) |
B |
362 |
47 |
EBOV 12.9% |
| Bundibugyo, Uganda47
|
2007 |
Adult contacts of survivors >18 y. Samples taken ~29 months after outbreak |
A |
210 |
2 |
EBOV/SUDV/TAFV/BDBV 1.0% |
ELISA (s) |
Mean OD of negative controls plus 3SD |
Antigens: EBOV, SUDV, Tai Forest ebolavirus (TAFV), Bundibugyo ebolavirus (BDBV), MARV(Mus)Validation: 28/36 confirmed cases tested positive to BDBV, 20/36 to EBOV, 10/36 to SUDV, 12/36 to TAFV & 29/39 to any of the 4 strains. |
15/223 contacts positive but 13 were symptomatic at the time of the outbreak, therefore only the 2 asymptomatic contacts are included in the table. |
| Republic of Congo48
|
2011 |
Healthy blood donors 18-65y, no known case exposure |
C |
809 |
20 |
EBOV 2.5% |
Double IFA |
Reciprocal endpoint titres ≥20 |
Antigens: EBOV (ATCC 1978), MARV (Popp 1967)Authors state: ‘double IFA’ technique has higher specificity than ‘regular’ IFA because only antibodies that detect filoviral antigens in co-localisation with a monoclonal antibody are considered. |
Seropositivity ranged from 1.6–4% depending on city/rural location; 4% in Pointe Noire. |
| Liberia [PREVAIL]49
|
2015 |
Close contacts of cases. NB 126 of the contacts were sexual partners of survivors after discharge. |
A |
760 |
98 |
EBOV 12.9% |
ELISA (Alpha) |
unspecified |
Antigen: EBOV |
Preliminary results. Study excluded from meta-analysis of known case contact group (A) because unclear what proportion of participants were symptomatic. |
| Kono, Sierra Leone50
|
2015-16 |
Asymptomatic close contacts of cases aged≥4 years who had been resident in quarantined houses during the period of active Ebola transmission |
A |
185 s |
12 |
EBOV 6.4% |
ELISA (Alpha) |
4.7 U/ml |
Antigen: EBOV GPValidation: 29/30 PCR-confirmed EVD survivors, and 3/132 community controls were positive: 96.7% sensitivity, 97.7% specificity |
2 other positives had fever. Not clear if negatives were asked about symptoms |
| Individuals from 3 villages without reported cases |
C |
132 |
3 |
2.3 |
| Western Area, Sierra Leone51
|
2015 |
Household contacts of cases, asymptomatic at the time EVD was in the household |
A |
388 |
10 |
EBOV 2.6% |
ELISA (PHE) |
Mean OD of negative controls+fixed OD measure (0.1) |
Antigen: EBOV GP. ‘Positive’ only if repeat test was positiveValidation: 93/97 PCR-confirmed EVD survivors and 0/339 community controls were positive: sensitivity 95.9% (95%CI 89.9–98.9%); specificity 100% (95%CI 98.9–100%) |
Tests were done on oral fluid. |
| Individuals from 3 villages in Western Area without reported EVD cases |
C |
339 |
0 |
EBOV 0% |
