Epidemiology of Ticks and Tick-Borne Pathogens in Domestic Ruminants across Southern African Development Community (SADC) Region from 1980 until 2021: A Systematic Review and Meta-Analysis

Epidemiology of Anaplasma species amongst cattle in Africa from 1970 to 2022: A systematic review and meta-analysis

Tick-borne pathogens of the genus Anaplasma cause anaplasmosis in livestock and humans, impacting health and livelihoods, particularly in Africa. A comprehensive review on the epidemiology of Anaplasma species is important to guide further research and for implementation of control approaches. We reviewed observational studies concerning Anaplasma species amongst cattle in Africa. Peer-reviewed studies published in PubMed, Google Scholar, and Web of Science - from database inception to 2022 - were searched. The quality of individual studies was assessed using the Joanna Briggs Institute Critical Appraisal Tool and the pooled prevalences by diagnostic method were estimated using random-effects models. Heterogeneity across the studies was tested and quantified using the Cochran's Q statistic and the I2 statistic. Potential sources of heterogeneity were investigated by subgroup analysis. A total of 1117 records were retrieved and at the end of the screening, 149 records (155 studies) were eligible for this meta-analysis. The occurrence of Anaplasma species was reported in 31/54 countries in all regions. Seven recognised species (A. marginale, A. centrale, A. phagocytophilum, A. platys, A. capra, A. bovis, A. ovis) and nine uncharacterised genotypes (Anaplasma sp. Hadesa; Anaplasma sp. Saso; Anaplasma sp. Dedessa; Anaplasma sp. Mymensingh; Anaplasma sp. Lambwe-1; Candidatus Anaplasma africae; Anaplasma sp.; Candidatus Anaplasma boleense) were reported in African cattle. Anaplasma marginale was the most frequently reported (n=144/155 studies) and the most prevalent species (serology methods 56.1%, 45.9-66.1; direct detection methods 19.9%, 15.4-24.7), followed by A. centrale (n=26 studies) with a prevalence of 8.0% (95% CI: 4.8-11.9) and A. platys (n=19 studies) with prevalence of 9.7% (95% CI: 5.4-15.2). Anaplasma marginale, A. centrale and A. platys were reported in all Africa's regions, while A. ovis and A. capra were reported only in the northern and central regions. The uncharacterised Anaplasma taxa were mostly detected in the eastern and southern regions. Subgroup analysis showed that significant determinants for A. marginale exposure (serology) were geographical region (p=0.0219), and longitude (p=0.0336), while the technique employed influenced (p<0.0001) prevalence in direct detection approaches. Temperature was the only significant variable (p=0.0269) for A. centrale. These findings show that various Anaplasma species, including those that are zoonotic, circulate in African cattle. There is need for more genetic and genome data, especially for unrecognised species, to facilitate effective identification, improve livestock and minimise the health risk in human populations. Additional epidemiological data including pathogen occurrence, tick vectors and host range, as well as pathogenicity are essential.

Evidence of zoonotic rickettsiae in ixodid ticks of domestic animals in some communal farms in the Eastern Cape Province, South Africa

Objective

The abundance of tick populations in South Africa represents a probable risk for both animal and human health. Rickettsia spp. and Borrelia spp. are well-known agents of emerging human tick-borne infectious diseases worldwide. Nevertheless, the epidemiology of their infections has been underreported in South Africa. Therefore, this study aimed to profile zoonotic Rickettsia and Borrelia species from ticks infesting domesticated animals in the Eastern Cape, South Africa.

Materials and Methods

Morphological and molecular identification techniques were conducted on 1,200 tick samples collected from domestic animals before screening for the target bacterial pathogens. The molecular identification of the tick samples was based on the amplification of the 12S rRNA mitochondrial Deoxyribonucleic acid. At the same time, those of Rickettsia and Borrelia species were carried out by amplifying fragments of gltA and ompB genes for Rickettsia and flaB gene for Borrelia spp. Thereafter, the positive amplicons for Rickettsia ompB were sequenced and further analyzed. Borrelia PCRs were negative; therefore, sequencing could not be performed.

Results

Eight species of ticks belonging to three genera; Rhipicephalus, Amblyomma, and Haemaphysalis, were identified. A total of 27% (320/1,200) samples were confirmed positive for Rickettsia, of which 23% (74/320) were positive for ompB genes. Phylogenetic analysis of ompB revealed a high homology to rickettsial reference strains from GenBank, with no positive result for Borrelia. The generated sequences showed homology with R. africae-KX227790 (100%), R. parkeri-KY113111 (99.8%), R. peacockii (99.3%), and R. slovaca-JX683122 (99.1%) representative sequences in GenBank.

Conclusion

The findings from this study revealed that ticks harbored Rickettsia species with possible zoonotic potential.

Current status of ruminant anaplasmosis in Algeria: a systematic review and meta-analysis

Anaplasmosis is an emerging infectious disease that is being recognised all over the world, with impact on animal health.This systematic review and meta-analysis aimed to assess the rate infection of Anaplasma spp. infection in Algerian ruminants. Three databases were searched to identify eligible studies for the final systematic review and meta-analysis. The 'meta' package in the R software was used for the meta-analysis, and the random effects model was chosen to pool the data. Meta-analysis encompasses 14 research papers spanning 19 years (2004-2023), out of an initial pool of 737 articles retrieved from various databases. The study included a total of 1515 cattle, 190 sheep, and 310 goats, and the overall Anaplasma infection rate was estimated at 28% (95% CI, 17-41%). The analysis revealed varying infection rates among species, with cattle at 20%, sheep at 30%, and goats at 61%. Five classified species and two unclassified strains belonging to Anaplasma genus were identified in ruminants, which are A. marginale, A. centrale, A. bovis, A. ovis, A. phagocytophilum, A. phagocytophilum-like strains, and A. platys-like strains. Among these, A. marginale was prevalent in ten out of eleven cattle studies. The data also revealed regional variations, with Northeastern Algeria showing a higher infection rate (26%) compared to North-central Algeria (9%). In the subgroup analysis, clinically healthy cattle had a higher infection rate (28%) compared to suspected disease cattle (16%). Molecular biology screening methods yielded a significantly higher infection rate (33%) than microscopy (12%). Gender analysis suggested slightly higher infection rates among male cattle (19%) compared to females (16%). Age analysis indicated that Anaplasma infection was more common in cattle less than 12 months (14%) compared to those over 12 months (9%). This systematic review provides valuable insights, highlighting the need for continued surveillance and potential preventive strategies in different regions and among different animal populations in Algeria.

Molecular diagnosis and characterization of Anaplasma marginale and Ehrlichia ruminantium infecting beef cattle of Maputo Province, Mozambique

BACKGROUND

Members of the Anaplasmataceae family, such as the Anaplasma and Ehrlichia species, cause economic losses and public health risks. However, the exact economic impact has not been comprehensively assessed in Mozambique due to limited data available on its basic epidemiology. Therefore, we investigated the molecular occurrence and identity of Anaplasma and Ehrlichia spp. infecting beef cattle in Maputo province, Mozambique.

METHODS

A total of 200 whole blood samples were collected from apparently healthy beef cattle. Whole blood DNA was extracted and tested for presence of Anaplasma spp. and Ehrlichia ruminantium DNA through amplification of the 16S rRNA and map1 genes. Positive samples to Anaplasma spp. were subject to PCR assay targeting the A. marginale-msp5 gene. Amplicons obtained were purified, sequenced and subject to phylogenetic analyses.

RESULTS

Anaplasma spp., A. marginale and E. ruminantium were detected in 153 (76.5%), 142 (71%) and 19 (9.5%) of all the samples analyzed, respectively. On this same sample group, 19 (9.5%) were co-infected with A. marginale and E. ruminantium. The 16S rRNA sequences of Anaplasma spp. obtained were phylogenetically related to A. marginale, A. centrale and A. platys. Phylogenetic analysis revealed that A. marginale-msp5 nucleotide sequences were grouped with sequences from Asia, Africa and Latin America, whereas E. ruminantium-map1 DNA nucleotide sequences were positioned in multiple clusters.

CONCLUSION

Cattle in Maputo Province are reservoirs for multiple Anaplasma species. A high positivity rate of infection by A. marginale was observed, as well as high genetic diversity of E. ruminantium. Furthermore, five new genotypes of E. ruminantium-map1 were identified.

Systematic Review and Meta-Analysis on Piroplasma spp. Infection and Co-infection with Anaplasma marginale in Domestic Ruminants from Algeria

BACKGROUND

Piroplasmosis and anaplasmosis stand out as the primary diseases affecting livestock during periods of tick activity. These vector-borne diseases continue to emerge worldwide, exerting a detrimental impact on both animal health and national economies. The purpose of this study is to assess the prevalence of Piroplasma spp. and its co-occurrence with Anaplasma marginale in domestic ruminants in Algeria.

METHODS

Three databases were systematically reviewed to identify eligible studies for the final meta-analysis, following the PRISMA statement. The 'meta' package in the R software was employed for the meta-analysis with the random effects model chosen for data pooling.

RESULTS

The meta-analysis encompasses 14 research papers spanning a 19-year period (2004-2023). Theileria spp. was identified in all studies, covering 1675 cattle, 190 sheep, and 128 goats, yielding an overall Theileria infection rate of 45% (95% CI 26-65%). Specifically, cattle had a 59% infection rate, while sheep and goats had rates of 18% and 20%, respectively. Babesia spp. was found in nine studies, involving 1183 cattle and 190 sheep, resulting in an overall Babesia infection rate of 7% (95% CI 4-15%), with cattle and sheep having rates of 10% and 3%, respectively. Notably, eight Piroplasma species T. annulata, T. orientalis, T. buffeli, T. equi, Theileria sp., B. bovis, B. bigemina, and B. occultans were detected in cattle, with T. annulata being the most prevalent at 54%. Regional disparities and host factors also impacted infection rates, with higher rates in Northeastern Algeria and among suspected disease cattle. Additionally, gender, age, and breed influenced cattle susceptibility to Theileria infection. Furthermore, six distinct co-infections between Piroplasma spp. and A. marginale were observed, with T. annulata/A. marginale identified in six studies, demonstrating an 8.3% co-infection rate.

CONCLUSION

This analysis offers crucial insights into the current status of Piroplasmosis and its co-infection with A. marginale in Algerian domestic ruminants, providing valuable data for surveillance and prevention strategies.

Hard ticks (Acari: Ixodidae) and tick-borne diseases of sheep and goats in Africa: A review

Ticks are leading vectors of economically important pathogens that affect small ruminants due to favourable climatic conditions across different regions of the African continent. They are responsible for both direct and indirect economic losses in the livestock industry. This review focuses on the species diversity of hard ticks, their biology, tick-borne diseases of sheep and goats including non-infectious disease, and risk factors to tick infestation in Africa. Furthermore, our review provides recent updates on distribution of ticks and tick-borne pathogens of small ruminants in Africa. It was observed that several species and subspecies of hard ticks belonging to the genera Hyalomma (Hy), Rhipicephalus (Rh), Ixodes (I) and Amblyomma (Am) were found infesting small ruminants across the different regions of the continent. Of these genera, Rhipicephalus ticks accounts for the majority of the registered species, with exactly 27 different species infesting small ruminant stocks comprising of different developmental instars and adults of the tick. Rhipicephalus decolaratus, Rh. e. evertsi and Rh. appendiculatus were the three most common Rhipicephalus species reported. Both protozoal (Babesia and Theileria) and bacterial (Anaplasma, Rickettsia, Ehrlichia, Coxiella and Mycoplasma) pathogens have being reported to be amplified in several hard tick species and/or small ruminant hosts. Furthermore, tick paralysis and lameness were non-infectious conditions attributed to tick infestations. Amblyomma hebraeum and Rh. glabroscutatum may cause lameness in goats, while Hy. rufipes is responsible for the same condition in Merino sheep. Host paralysis due to a neurotoxin released by female Rh. e. evertsi and I. rubicundus has been documented within the continent. We therefore advocate for the need of integrated control measures against tick-borne pathogens (TBPs) including their arthropod vectors, to be performed simultaneously to ease the burden of vector-borne diseases in small ruminant production.

Current Status and Challenges Associated with Tick-Borne Pathogens and Diseases: Where Do We Stand?

Lyme Borreliosis (LB), caused by Borrelia burgdorferi sensu lato (s [...].

Molecular detection of Coxiella burnetii and Coxiella species in rats and chickens from poultry farms in North West Province, South Africa

BACKGROUND

Coxiella burnetii is a bacterial pathogen that causes query fever and coxiellosis in humans and animals, respectively. There is a scarcity of studies on the prevalence of C. burnetii infections in rats and chickens in South Africa.

OBJECTIVE

The aim of this study was to determine the occurrence of C. burnetii in rats and chickens sampled from poultry farms in the North West Province of South Africa.

METHODS

DNA was extracted from rodent kidneys (n = 68) and chicken faeces (n = 52). Two rodent pest species, namely Rattus rattus and Rattus tanezumi, were identified by analysis of CO1 gene sequences. Detection of C. burnetii was carried out using polymerase chain reaction assays targeting 23S rRNA, 16S rRNA and IS111 markers.

RESULTS

C. burnetii was detected in 16.2%, 8.8% and 25% of R. rattus, R. tanezumi and chickens, respectively.

CONCLUSIONS

The findings in this study demonstrate that rodents and chickens are harbouring C. burnetii at sampled poultry farms. There should be frequent screening for C. burnetii in poultry operations. The likelihood of future transmission between rodents and chickens, including humans, also needs to be investigated.

Monitoring of hard tick parasitism in domestic ruminants: A scale evidence for policymakers

Domestic ruminants such as camels, cattle, goats, and sheep represent a substantial part of the global world economy. Hard ticks are well-known as obligatory bloodsucking ectoparasites of domestic ruminants. Policymakers need to get results that show the global distribution of tick genera and species, their parasitic levels, and their roles as disease vectors in camels, cattle, goats, and sheep. Iran is endemic to a broad range of hard tick-borne diseases. A study that reviews the tick genera and species, life stage, seasonal and attachment site parasitism levels, the global mean ranks of tick species parasitism rates and records, and their distribution in target animals would be of particular importance. Accordingly, this review aims to summarize the above objectives. After evaluating the identified articles, 147 were selected to be part of the survey based on the study objectives. Globally, tick parasitism levels were 28.7, 29.9, 36.0 and 47.6% for goats, cattle, sheep, and camels, respectively. The tick parasitism trends have exhibited an increasing trend for camels and sheep over the years while remaining constant for cattle and goats, indicating that current tick control measures are not being properly followed. Ticks tend to parasitize females more than males because males are more resistant to certain pests than females. The distribution of tick genera and species, their parasitism levels, and their roles as disease vectors provided. This information addresses the needs of decision-makers to make decisions.