Cape Town – Residents of rural communities in South Africa face a barrage of problems from high poverty rates, low access to clean drinking water, a high burden of chronic disease, inadequate access to quality health care, poor transportation, a dependence on agriculture on a small scale level and low literacy levels to name a few.
The Mnisi community, a rural area in the Mpumalanga Province, is no different. Only it is also battling a particular bacteria, the description of which is quite extensive and scientific – small, spherical, pleomorphic, non-motile, and gram-negative.
Dr Agatha Kolo, conducted the study under the mentorship of Prof Marinda Oosthuizen, the Deputy Dean research and Postgraduate studies at the Faculty of Veterinary Science, University of Pretoria.
She explains that Anaplasma spp. belong to a group of bacteria called “alphaproteobacteria”, and they live and multiply in the cytoplasm of eukaryotic host cells. Eukaryotes are organisms that have a clearly outlined nucleus and Anaplasma spp. are transmitted to vertebrate animals through the bite of infected hard ticks and cause disease in animals and humans.
Kolo’s study focused on Anaplasma phagocytophilum. She explains that the species is a bacterium infecting neutrophils, a type of white blood cell. It causes human granulocytic anaplasmosis (HGA), an important tick-borne zoonosis worldwide – zoonosis refers to diseases that affect both humans and animals.
The paper, published in the journal Microorganisms, says that clinical signs of the disease in humans range from mild febrile illness to a life-threatening condition often characterised as acute fibrile illness (AFI).
AFI is defined as a patient with fever of 38°C or higher at presentation to an emergency department or history of fever that persisted for 2-7 days with no localising source.
‘Proliferation of tick vectors’
Kolo said the study is an important contribution to the Foundational Biodiversity Information Programme’s (FBIP) theme of Global Change as it documents the diversity of species of pathogens and their host vectors that affect human and animal health.
“Climate change is generally regarded as a main contributor to Global Change. Ongoing research worldwide has suggested that global warming and climate change will favour the proliferation of tick vectors, leading to an increase in human and animal tick bites and increase the susceptibility to life threatening infections,” she says.
The study formed part of Prof Oosthuizen’s 2017 funded FBIP small project.
The study’s sample set consisted of 282 wild rodents trapped across three habitat types, 74 acute fibrile illness (AFI) patients, 56 domestic dogs, 100 cattle and 160 Rhipicephalus sanguineus ticks collected from dogs.
Of these, the bacterial blood microbiome of a subset of samples was generated using the single molecule real-time (SMRT) sequencing on the Pacific Biosciences platform at Washington State University, USA – SMRT sequencing is a relatively new type of next generation sequencing.
The entire sample set was thereafter screened for the specific presence of A. phagocytophilum using a real-time Polymerase Chain Reaction (PCR) assay.
Sequencing of the 16S rRNA and gltA genes confirmed the presence of A. phagocytophilum DNA in humans, dogs and rodents.
Kolo says the finding is important because it serves as the first report of the molecular detection of the emerging zoonotic tick-borne pathogen A. phagocytophilum in humans, domestic dogs and rodents in a rural community in South Africa. It also reports on the detection of another known zoonotic agent, A. platys, in domestic dogs and their ticks.
“The detection of these emerging zoonotic pathogens from various hosts in a rural community in South Africa underscores the possible risk of human infection that may occur with these agents,” she says.
The study recommends that primary health care practitioners in the Mnisi community consider A. phagocytophilum in the differential diagnosis of non-malarial acute febrile illness, which will help to guide appropriate treatment.
Prior research conducted in the Mnisi community suggested that undifferentiated non-malarial AFI was the most common presenting sign in patients seeking healthcare at the community clinics.
Given the number of potential zoonotic agents identified in the study, Kolo and her colleagues recommended that residents of the Mnisi community should be educated on effective tick and rodent control, keeping food out of the reach of rodents and observing good sanitary practices to reduce the rodent population around households.
Kolo believes these practices will help in the overall reduction of zoonotic disease burden in the community. In addition, the One Health Platform of the Department of Veterinary Tropical Diseases, University of Pretoria, helps organise community engagement activities with the local Mnisi Traditional authority to pass on such important information to the community.
The study also recommended that the current cattle dipping regimen practised in the community be improved, as there is a persistent infestation of cattle with hard ticks.
“I believe that the implementation of these recommendations by the relevant regulatory authorities in the long term will improve the quality of the lives of residents of Mnisi community and other communities in rural South Africa,” Kolo says.