Risk factors for bacterial zoonotic pathogens in acutely febrile patients in Mpumalanga Province, South Africa

Aetiologies of bacterial tick-borne febrile illnesses in humans in Africa: diagnostic limitations and the need for improvement

Tick-borne febrile illnesses caused by pathogens like Anaplasma spp., Bartonella spp., Borrelia spp., Ehrlichia spp., Coxiella burnetii, Francisella tularensis, and Rickettsia spp., are significant health concerns in Africa. The epidemiological occurrence of these pathogens is closely linked to the habitats of their vectors, prevalent in rural and semi-urban areas where humans and livestock coexist. The overlapping clinical presentations, non-specific symptoms, and limited access to commercially available in vitro diagnostics in resource-limited settings exacerbate the complexity of accurate diagnoses. This review aimed to systematically extract and analyze existing literature on tick-borne febrile illnesses in Africa, highlighting the diagnostic challenges and presenting an up-to-date overview of the most relevant pathogens affecting human populations. A comprehensive literature search from January 1990 to June 2024 using databases like PubMed, Cochrane Library, Science Direct, EMBASE, and Google Scholar yielded 13,420 articles, of which 70 met the inclusion criteria. Anaplasma spp. were reported in Morocco, Egypt, and South Africa; Francisella spp. in Kenya and Ethiopia; Ehrlichia spp. in Cameroon; Bartonella spp. in Senegal, Namibia, South Africa, and Ethiopia; Borrelia spp. in Senegal, Gabon, Tanzania, and Ethiopia; Coxiella burnetii in 10 countries including Senegal, Mali, and South Africa; and Rickettsia spp. in 14 countries including Senegal, Algeria, and Uganda. Data were analyzed using a fixed-effect model in R version 4.0.1 and visualized on an African map using Tableau version 2022.2. This review highlights the urgent need for improved diagnostics to better manage and control tick-borne febrile illnesses in Africa.

Eco-epidemiological study of seropositivity against Rickettsia and Leptospira agents in rural areas of Urabá, Colombia

Rickettsioses and leptospirosis are infectious diseases that are often underdiagnosed due to a lack of knowledge about their epidemiology, pathophysiology, diagnosis, management, among others.

Objetive

to characterize the seroprevalence and seroincidence of both Rickettsia and Leptospira agents and determine the risk factors for these outcomes in rural areas of Urabá, Antioquia.

Methods

a secondary data analysis using information on Rickettsia and Leptospira exposure from a prior prospective study that explored sociocultural and ecological aspects of Rickettsia infection in rural Urabá, Colombia. A multinomial mixed logistic regression model was employed to analyze factors linked to seroprevalent cases of Rickettsia, Leptospira and both, along with descriptive analyses of seroincident cases.

Results

the concomitant seroprevalence against Rickettsiaand Leptospira was 9.38% [95%CI 6.08%-13.37%] (56/597). The factors associated with this seroprevalence were age (ORa= 1.02 [95%CI 1.007-1.03]), male gender (ORa= 3.06 [95%CI 1.75-5.37]), fever history (ORa= 1.71 [95%CI 1.06-2.77]) the presence of breeding pigs (ORa= 2.29 [95%CI 1.36-3.88]), peridomicile yucca crops(ORa= 2.5 [95%CI 1.1-5.62]), and deforestation practices(ORa= 1.74 [95%CI 1.06-2.87]). The concomitant seroincidence against Rickettsia and Leptospira was 1.09% (3/274) [95%CI 0.29%-4.05%], three cases were female, with a median age of 31.83 years-old (IQR 8.69-56.99). At the household level, all the seroincident cases had households built partially or totally with soil floors, wooden walls, and zinc roofs. Two seroincident cases described the presence of equines, canines, and domestic chickens in intra or peri-domicile. Finally, two cases were exposed to synanthropic rodents, and one case to tick infestation.

Conclusion

there is evidence of seroprevalent and seroincident cases of seropositivity against both Rickettsia and Leptospira in rural areas of Urabá, Colombia. These findings can help improve public health surveillance systems in preventing, detecting, and attending to the different clinical cases caused by these pathogens.

Gender and zoonotic pathogen exposure pathways in a resource-limited community, Mpumalanga, South Africa: A qualitative analysis

The Mnisi community is a livestock-dependent community neighboring the Great Limpopo Transfrontier Conservation Area in South Africa. Here, zoonotic pathogens contribute to as many as 77% of cases of acute febrile illness. Previous gender-disaggregated analysis in the community has shown that men and women have different risks of zoonotic illness, suggesting that exposure routes for zoonotic infections should be further explored to inform gender-sensitive risk mitigation strategies. Using a One Health approach and ethnographic methodology, we examined interactions between community residents, domestic animals, and the built and natural environment to investigate potential exposure pathways for zoonotic infections from a gendered perspective. We combined data from direct household observations and focus group discussions on previously identified gendered tasks such as domestic animal care, water collection, and food preparation, and how and by whom these tasks were performed. We noted gender differences for household tasks, animal care duties, and environmental exposure. Both men and women access grazing land but for different tasks (water collection-females, cattle grazing-males), and both men and women experience more time in the bush in recent years due to decreased water availability. From observations, it was noted that men wore covered protective work clothes (such as long trousers and closed-toe shoes) more commonly than women did; women did not often wear these for household duties including water collection in the bush. We recommend that these gender-typed roles serve as critical control points for zoonotic pathogen exposure. For example, tick-bite exposure prevention should be directed at both men and women based on their daily activities, but prevention in men should target exposure from cattle and prevention in women should focus on personal protective measures during water and firewood collection. These findings can contribute to a more detailed understanding of the role of human behavior and critical control points for zoonotic disease-a significant contributor to acute febrile illness in this rural, resource-limited setting.

Rickettsia africae infection rates and transovarial transmission in Amblyomma hebraeum ticks in Mnisi, Bushbuckridge, South Africa

Rickettsia africae is a gram-negative bacterium, which causes African tick bite fever (ATBF) in humans. ATBF is a febrile disease mainly affecting travellers to southern Africa. This bacterium is known to be transmitted by Amblyomma hebraeum and Amblyomma variegatum ticks. In southern Africa, the principal vector is A. hebraeum. Febrile disease is a serious issue in the study area. There is a high prevalence of non-malaria illness caused by Rickettsia, so there is a need to have more knowledge on these species. Infection rates and transovarial transmission efficiency of R. africae in A. hebraeum ticks were investigated in a rural area of Mpumalanga province, South Africa. Adult and engorged A. hebraeum female ticks were collected from cattle. Larvae were collected by dragging a cloth at ground level using 100 steps, equivalent to an area of 100 m². Tick identification was performed according to standard taxonomic keys using a microscope. Engorged ticks were incubated to oviposit and egg masses were collected. DNA was extracted from the ticks, larvae and egg masses, and screened for gltA and ompA genes, using quantitative real-time PCR and conventional PCR, respectively. Positive ompA amplicons were sequenced and phylogenetic analysis showed 99.8-100% identity with R. africae. Infection rates were 13.7 and 12.7% for adults and larvae, respectively. Transovarial transmission of R. africae in A. hebraeum from this study was 85.7%. The results provide a clear indication that people living in the study area and travellers that visit the area are at risk of contracting ATBF.

Research priorities for control of zoonoses in South Africa

BACKGROUND

Zoonoses pose major threats to the health of humans, domestic animals and wildlife, as seen in the COVID-19 pandemic. Zoonoses are the commonest source of emerging human infections and inter-species transmission is facilitated by anthropogenic factors such as encroachment and destruction of wilderness areas, wildlife trafficking and climate change. South Africa was selected for a 'One Health' study to identify research priorities for control of zoonoses due to its complex disease burden and an overstretched health system.

METHODS

A multidisciplinary group of 18 experts identified priority zoonotic diseases, knowledge gaps and proposed research priorities for the next 5 y. Each priority was scored using predefined criteria by another group of five experts and then weighted by a reference group (n=28) and the 18 experts.

RESULTS

Seventeen diseases were mentioned with the top five being rabies (14/18), TB (13/18), brucellosis (11/18), Rift Valley fever (9/11) and cysticercosis (6/18). In total, 97 specific research priorities were listed, with the majority on basic epidemiological research (n=57), such as measuring the burden of various zoonoses (n=24), followed by 20 on development of new interventions. The highest research priority score was for improving existing interventions (0.77/1.0), followed by health policy and systems research (0.72/1.0).

CONCLUSION

Future zoonotic research should improve understanding of zoonotic burden and risk factors and new interventions in public health. People with limited rural services, immunocompromised, in informal settlements and high-risk occupations, should be the highest research priority.

Serological Evidence of Rickettsia Exposure among Patients with Unknown Fever Origin in Angola, 2016-2017

Spotted fever group Rickettsia (SFGR) is one among the aetiologies that cause fever of unknown origin in Angola. Despite their occurrence, there is little information about its magnitude in this country either because it is misdiagnosed or due to the lack of diagnostic resources. For this purpose, eighty-seven selected malaria- and yellow fever-negative serum specimens collected between February 2016 and March 2017 as part of the National Laboratory of Febrile Syndromes, from patients with fever (≥37.5°C) for at least 4 days and of unknown origin, were screened for Rickettsia antibodies through an immunofluorescence assay (IFA). Serological results were interpreted according to the 2017 guidelines for the detection of Rickettsia spp. Three seroreactive patients had detectable IgM antibodies to Rickettsia with an endpoint titre of 32 and IgG antibodies with endpoint titres of 128 and 256. These findings supported a diagnosis of Rickettsia exposure amongst these patients and highlight that rickettsioses may be among the cause of unknown febrile syndromes in Angola. Therefore, physicians must be aware of this reality and must include this vector-borne disease as part of aetiologies that should be considered and systematically tested in order to delineate appropriate strategies of diagnostic and control of Rickettsia in Angola.

Gender Roles and One Health Risk Factors at the Human-Livestock-Wildlife Interface, Mpumalanga Province, South Africa

Gender sensitivity in health promotion has been widely recommended, yet attention to gender roles and gender-disaggregated studies is often lacking in disease research and public health intervention planning. In the rural Mnisi community of Mpumalanga, South Africa, where zoonotic pathogens are known to contribute to acute febrile illness, community and household tasks may increase an individual's risk of exposure, and these tasks are likely to be influenced by gender. This study described the roles and responsibilities of community residents, specifically those that have been identified as critical control points for infectious pathogen exposure, by gender. Male gender-typed tasks included those associated with livestock and poultry husbandry, hunting and slaughtering wildlife, and rodent control. Female gender-typed tasks included animal-sourced food preparation, domestic cleaning and maintenance, and caregiving to children and ill family members. Given the gender-specific nature of these tasks, potential pathogen exposure and transmission patterns of infectious diseases may be also gender specific. These data can inform the development and revision of health promotion strategies, such as the community-based One Health Training and Leadership program, prioritizing outcomes for male and female participants alike. Gender-disaggregated analysis is recommended for effective risk mitigation and community-wide health promotion using a One Health approach.

Sero-Epidemiological Study of Selected Zoonotic and Abortifacient Pathogens in Cattle at a Wildlife-Livestock Interface in South Africa

A cross sectional sero-epidemiological study was conducted on cattle in a communal farming area adjacent to Kruger National Park at a wildlife-livestock interface in South Africa. A total of 184 cattle were screened for exposure to 5 abortifacient or zoonotic pathogens, namely Coxiella burnetii, Toxoplasma gondii, Chlamydophila abortus, Neospora caninum, and Rift Valley fever virus (RVFV) using enzyme-linked immunosorbent assays. In addition, the virus neutralization test was used to confirm the presence of antibodies to RVFV. The seroprevalence of C. burnetii, T. gondii, C. abortus, N. caninum, and RVFV antibodies was 38.0%, 32.6%, 20.7%, 1.6%, and 0.5%, respectively, and varied between locations (p < 0.001). Seroprevalence of C. burnetii and T. gondii was highly clustered by location (intraclass correlation coefficient [ICC] = 0.57), and that of C. abortus moderately so (ICC = 0.11). Seroprevalence was not associated with sex or age for any pathogen, except for C. abortus, for which seroprevalence was positively associated with age (p = 0.01). The predominant mixed infections were C. burnetii and T. gondii (15.2%) and C. burnetii, T. gondii, and C. abortus (13.0%). The serological detection of the five abortifacient pathogens in cattle indicates the potential for economic losses to livestock farmers, health impacts to domestic animals, transmission across the livestock-wildlife interface, and the risk of zoonotic transmission. This is the first documentation of T. gondii infection in cattle in South Africa, while exposure to C. burnetii, C. abortus, and N. caninum infections is being reported for the first time in cattle in a wildlife-livestock interface in the country.