Toward closing a heartwater monitoring gap with a new pan-species ELISA suitable for domestic ruminants, wildlife, and camels.
- 1CIRAD
Abstract
Heartwater, caused by the tick-borne bacterium Ehrlichia ruminantium, threatens ruminant production in sub-Saharan Africa and the Caribbean. Serological surveillance relies on species-specific ELISAs, so wildlife and camelids, which are potential reservoirs or sentinels, have no validated tools. We developed and evaluated a pan-species indirect ELISA prototype (ID Screen Ehrlichia ruminantium Indirect Multi-species, Innovative Diagnostics) that detects anti-MAP1-B antibodies in all mammals. A positivity threshold of 30% relative positivity percentage (RPP) was empirically established from 707 heartwater-negative cattle, goat and sheep sera from three regions (maximum RPP 22.1%). Against a goat-specific reference ELISA (n = 503), the prototype showed 98.2% sensitivity, 97.2% specificity and 97.6% overall agreement. ROC analysis identified a Youden-optimal cut-off of 29.96%, confirming the empirical threshold. Inter-assay reproducibility was satisfactory (mean CV 7.4%), and qualitative classification remained stable across runs, including for a near-threshold sample. In four vaccinated sheep, the prototype detected seroconversion at the same time points as a sheep-specific ELISA. In non-domestic hosts, the assay gave uniformly low RPP values in 24 zoo animals of ten species from a heartwater-free area. By contrast, 4.5% of 111 dromedary camels from Chad exceeded the threshold. Eight wildlife species from Kruger National Park (n = 405) were tested and five species presented high median RPP values. This single-protocol assay provides a reproducible tool for integrated heartwater surveillance across livestock, camelids and wildlife, in Africa, in the Caribbean and in all countries threatened by the emergence of heartwater.
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BibTeX
@misc{rodrigues2026toward,
title = {{Toward closing a heartwater monitoring gap with a new pan-species ELISA suitable for domestic ruminants, wildlife, and camels.}},
author = {V. RODRIGUES and L. Viry and a. monteil and m. dhune and m. bayet and p. pourquier and v. Ollivier and f. donnet and d. morar-leather and z. Dlamkile and L. Neves and D. F. Meyer},
howpublished = {bioRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.29.762616},
url = {https://www.biorxiv.org/content/10.64898/2026.10.29.762616v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Toward closing a heartwater monitoring gap with a new pan-species ELISA suitable for domestic ruminants, wildlife, and camels.
AU - V. RODRIGUES
AU - L. Viry
AU - a. monteil
AU - m. dhune
AU - m. bayet
AU - p. pourquier
AU - v. Ollivier
AU - f. donnet
AU - d. morar-leather
AU - z. Dlamkile
AU - L. Neves
AU - D. F. Meyer
PY - 2026
DA - 2026/10/29
PB - bioRxiv
DO - 10.64898/2026.10.29.762616
UR - https://www.biorxiv.org/content/10.64898/2026.10.29.762616v1
AB - Heartwater, caused by the tick-borne bacterium Ehrlichia ruminantium, threatens ruminant production in sub-Saharan Africa and the Caribbean. Serological surveillance relies on species-specific ELISAs, so wildlife and camelids, which are potential reservoirs or sentinels, have no validated tools. We developed and evaluated a pan-species indirect ELISA prototype (ID Screen Ehrlichia ruminantium Indirect Multi-species, Innovative Diagnostics) that detects anti-MAP1-B antibodies in all mammals. A positivity threshold of 30% relative positivity percentage (RPP) was empirically established from 707 heartwater-negative cattle, goat and sheep sera from three regions (maximum RPP 22.1%). Against a goat-specific reference ELISA (n = 503), the prototype showed 98.2% sensitivity, 97.2% specificity and 97.6% overall agreement. ROC analysis identified a Youden-optimal cut-off of 29.96%, confirming the empirical threshold. Inter-assay reproducibility was satisfactory (mean CV 7.4%), and qualitative classification remained stable across runs, including for a near-threshold sample. In four vaccinated sheep, the prototype detected seroconversion at the same time points as a sheep-specific ELISA. In non-domestic hosts, the assay gave uniformly low RPP values in 24 zoo animals of ten species from a heartwater-free area. By contrast, 4.5% of 111 dromedary camels from Chad exceeded the threshold. Eight wildlife species from Kruger National Park (n = 405) were tested and five species presented high median RPP values. This single-protocol assay provides a reproducible tool for integrated heartwater surveillance across livestock, camelids and wildlife, in Africa, in the Caribbean and in all countries threatened by the emergence of heartwater.
ER -