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<p>Anaplasmosis, a zoonotic disease caused by <i>Anaplasma</i> species, threatens Somalia’s dromedary population, crucial to the nation’s economy and society. This study examines its occurrence in dromedaries from two Somali bioclimatic regions using molecular and serological methods. A total of 155 blood and serum samples from dromedaries in Benadir and Lower Shabelle were analyzed. Serum samples underwent rMSP5-based ELISA for anti-<i>Anaplasma marginale</i> IgG antibodies. DNA was extracted from dromedary blood samples followed by molecular screening included nested PCR for the 16S rRNA gene of <i>Anaplasma</i> spp. and qPCR for the <i>msp1β</i> gene of <i>A. marginale</i>. Positive samples underwent further PCR and sequencing targeting five additional genes for definitive species confirmation and phylogenetic analysis. Of 155 dromedaries tested, 30 (19.4%) were seropositive for <i>Anaplasma marginale</i> by iELISA, and 117 (75.5%) were qPCR-positive for the <i>msp1β</i> gene. Notably, 97 animals that were seronegative by iELISA tested positive by qPCR, and the overall agreement between the two tests was substantial (κ = 0.62). Among 22 qPCR-positive samples, semi-nested PCR (snPCR) targeting the <i>msp1α</i> gene detected six positives (27.3%). The molecular prevalence of <i>A. marginale</i> was significantly higher in Benadir (84.6%) compared to Lower Shabelle (56.9%). A significant association was also observed between <i>A. marginale</i> infection and tick infestation, with infested dromedary camels showing lower odds of being positive (OR = 0.4). Initial nPCR screening identified <i>Anaplasma</i> spp. positive in 45 (29%) of animals, with 23 (14.8%) showing co-infections between <i>A. marginale</i> and <i>Anaplasma</i> spp. Further analysis of 25 selected nPCR-positive samples revealed positivity for ITS 17 (68%), <i>groEL</i> 12 (48%), and <i>gltA</i> 15 (60%) genes, though <i>msp4</i> was not detected. Phylogenetic analysis of 16S rRNA sequences showed clustering with ‘<i>Candidatus</i> Anaplasma camelii’ from Saudi Arabian dromedaries. This is the first report of ‘<i>Ca.</i> A. camelii’ and <i>A. marginale</i> in dromedary from Somalia, highlighting the need for further research on its impact on animal health.</p>

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First report of ‘Candidatus Anaplasma camelii’ and high molecular prevalence of Anaplasma marginale in dromedary camels (Camelus dromedarius) from Somalia

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  • 发表日期：

    2026年2月20日

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  • Aamir M. Osman,
  • Abdalla M. Ibrahim,
  • Ahmed A. Hassan-Kadle,
  • Marcos R. André,
  • Flávia C. M. Collere,
  • Anna C. B. Mongruel,
  • Daniel Lee,
  • Caroline Tostes Secato,
  • Thállitha S. W. J. Vieira,
  • Rosangela Z. Machado,
  • Rafael F. C. Vieira

摘要

Anaplasmosis, a zoonotic disease caused by Anaplasma species, threatens Somalia’s dromedary population, crucial to the nation’s economy and society. This study examines its occurrence in dromedaries from two Somali bioclimatic regions using molecular and serological methods. A total of 155 blood and serum samples from dromedaries in Benadir and Lower Shabelle were analyzed. Serum samples underwent rMSP5-based ELISA for anti-Anaplasma marginale IgG antibodies. DNA was extracted from dromedary blood samples followed by molecular screening included nested PCR for the 16S rRNA gene of Anaplasma spp. and qPCR for the msp1β gene of A. marginale. Positive samples underwent further PCR and sequencing targeting five additional genes for definitive species confirmation and phylogenetic analysis. Of 155 dromedaries tested, 30 (19.4%) were seropositive for Anaplasma marginale by iELISA, and 117 (75.5%) were qPCR-positive for the msp1β gene. Notably, 97 animals that were seronegative by iELISA tested positive by qPCR, and the overall agreement between the two tests was substantial (κ = 0.62). Among 22 qPCR-positive samples, semi-nested PCR (snPCR) targeting the msp1α gene detected six positives (27.3%). The molecular prevalence of A. marginale was significantly higher in Benadir (84.6%) compared to Lower Shabelle (56.9%). A significant association was also observed between A. marginale infection and tick infestation, with infested dromedary camels showing lower odds of being positive (OR = 0.4). Initial nPCR screening identified Anaplasma spp. positive in 45 (29%) of animals, with 23 (14.8%) showing co-infections between A. marginale and Anaplasma spp. Further analysis of 25 selected nPCR-positive samples revealed positivity for ITS 17 (68%), groEL 12 (48%), and gltA 15 (60%) genes, though msp4 was not detected. Phylogenetic analysis of 16S rRNA sequences showed clustering with ‘Candidatus Anaplasma camelii’ from Saudi Arabian dromedaries. This is the first report of ‘Ca. A. camelii’ and A. marginale in dromedary from Somalia, highlighting the need for further research on its impact on animal health.