Molecular detection of Rickettsia africae in Amblyomma ticks collected in cattle from Southern and Central Mozambique

Abstract

Introduction: Rickettsia are Gram-negative and obligate intracellular bacteria, which cause typhus and spotted fever-like diseases in humans. In Africa, Rickettsia africae of the Spotted Fever Group Rickettsia (SFGR) is the etiologic agent of the African Tick-Bite Fever. The disease is transmitted by ticks of the genus Amblyomma, which serve as vectors and reservoirs of Rickettsia. In this study, we aimed to detect Rickettsia species in ticks collected from cattle in south and central Mozambique.
 Methodology: DNA from 412 adult ticks and 22 pools of larvae were extracted and tested for the presence of Rickettsia genes gltA, ompA and ompB by PCR, followed by sequencing and phylogenetic analysis.
 Results: Our results showed that in adult ticks, 79.5% (n = 330), 66% (n = 274) and 67% (n = 275) samples were positive for gltA, ompA and ompB genes, respectively. Among the 22 pools of larvae analysed, 77.2% (n = 17) were positive for the three genes tested. The infection rates ranged from 43% to 100% for Rickettsia by gltA in all locations studied, with maximum values of 100% observed in the districts of Maputo province namely Changalane, Boane and Matutuine district. The phylogenetic analysis of amplified sequences revealed that samples under study grouped with R. africae for the 3 genes.
 Conclusion: The study showed that Spotted Fever Group Rickettsia represented by R. africae widely circulate in Amblyomma ticks collected in south and central regions of Mozambique.

Entomological risk of African tick-bite fever (Rickettsia africae infection) in Eswatini

“…africae in Amblyomma ticks is consistent with previous studies from southern Africa. While most of these studies only tested the infection rate for the adult life stage, our prevalence range of 52–90% in larvae is comparable to that found in adults (60–80%) [ 24 , 28 – 30 , 48 ]. This result provides evidence that the proportion of infected individuals remains relatively constant over both life stages and generation, suggesting efficient transstadial and transovarial transmission in nature.…”

“…Rickettsia africae infection in A . hebraeum is high, typically ranging from 60–80% [ 26 – 30 ]. Previous studies testing for R .…”

“…Previous studies testing for R . africae in any region have either not included larvae [ 31 , 32 ] or failed to identify Amblyomma larvae to the species level [ 30 , 33 ]. Given that several species of Amblyomma ticks co-occur with A .…”

A Pilot Study on the Microbiome of Amblyomma hebraeum Tick Stages Infected and Non-Infected with Rickettsia africae

“…It was assumed Rickettsia spp. would dominate the samples as A. hebraeum is the principal vector of R. africae , evidently the study conducted by Magaia et al [ 28 ] confirmed that 80% of A. hebraeum ticks were infected with R. africae in Mozambique. As with other taxa presented in this study, nymphs had a higher relative abundance of Rickettsia spp.…”

Rickettsia -Host-Tick Interactions: Knowledge Advances and Gaps

“…Transstadial and transovarial transmissions of R. africae have been reported for A. hebraeum ( 145 , 146 ). A recent PCR analysis identified that most Amblyomma ticks (up to 100%) collected from cattle in south and central Mozambique are infected with R. africae ( 143 ). Similarly, R. africae infection was prevalent in A. variegatum ticks (87%) on cattle in Madagascar ( 147 ).…”