Bovine brucellosis is endemic in Rwanda; however, little information is available on seroprevalence and risk factors. Therefore, a cross-sectional study was conducted among cattle farmed at the wildlife-livestock-human interface (n = 1691) in five districts and one peri-urban district (n = 216). Cattle were screened using the Rose Bengal test, then the results were confirmed by indirect enzyme-linked immunesorbent assay. Potential risk factors were determined with a questionnaire and analyzed for their association with seropositivity. In all districts, the animal and herd-level seroprevalence was 7.4% (141/1907) and 28.9% (61/212), respectively, 8.3% (141/1691) and 30.9% (61/198) at the interface, and 0.0% (0/216) in peri-urban areas. Among the potential risk factors, old age (≥5 years), cattle farmed close to wildlife, herds of cattle and small ruminants, history of abortions, and replacement animals were significantly associated with brucellosis (p < 0.05). Low awareness of zoonotic brucellosis, assisting calving without biosafety protection, drinking raw milk, and manual milking were each observed in more than 21.7% of cattle keepers whose herds were seropositive. This study confirmed brucellosis endemicity in cattle farmed close to wildlife in Rwanda, suggesting the need to focus control efforts in these areas. Educated farmers with a high awareness of zoonotic brucellosis had low bovine brucellosis seropositivity, which emphasizes the importance of education.

Background Glossina (tsetse flies) biologically transmit trypanosomes that infect both humans and animals. Knowledge of their distribution patterns is a key element to better understand the transmission dynamics of trypanosomosis. Tsetse distribution in Rwanda has not been well enough documented, and little is known on their current distribution. This study determined the current spatial distribution, abundance, diversity, and seasonal variations of tsetse flies in and around the Akagera National Park. Methods A longitudinal stratified sampling following the seasons was used. Biconical traps were deployed in 55 sites for 6 consecutive days of each study month from May 2018 to June 2019 and emptied every 48 h. Flies were identified using FAO keys, and the number of flies per trap day (FTD) was used to determine the apparent density. Pearson chi-square (χ2) and parametrical tests (t-test and ANOVA) were used to determine the variations between the variables. The significance (p < 0.05) at 95% confidence interval was considered. Logistic regression was used to determine the association between tsetse occurrence and the associated predictors. Results A total of 39,516 tsetse flies were collected, of which 73.4 and 26.6% were from inside Akagera NP and the interface area, respectively. Female flies accounted for 61.3 while 38.7% were males. Two species were identified, i.e. G. pallidipes [n = 29,121, 7.4 flies/trap/day (FTD)] and G. morsitans centralis (n = 10,395; 2.6 FTD). The statistical difference in numbers was significant between the two species (p = 0.000). The flies were more abundant during the wet season (15.8 FTD) than the dry season (4.2 FTD). Large numbers of flies were trapped around the swamp areas (69.1 FTD) inside the park and in Nyagatare District (11.2 FTD) at the interface. Glossina morsitans was 0.218 times less likely to occur outside the park. The chance of co-existing between the two species reduced outside the protected area (0.021 times). Conclusions The occurrence of Glossina seems to be limited to the protected Akagera NP and a narrow band of its surrounding areas. This finding will be crucial to design appropriate control strategies. Glossina pallidipes was found in higher numbers and therefore is conceivably the most important vector of trypanosomosis. Regional coordinated control and regular monitoring of Glossina distribution are recommended. Graphic Abstract

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Background African Trypanosomiases threaten the life of both humans and animals. Trypanosomes are transmitted by tsetse and other biting flies. In Rwanda, the AAT endemic area is mainly around the tsetse-infested Akagera National Park (NP). The study aimed to identify Trypanosoma species circulating in cattle, their genetic diversity and distribution around the Akagera NP. Methodology A cross-sectional study was carried out in four districts, where 1,037 cattle blood samples were collected. The presence of trypanosomes was determined by microscopy, immunological rapid test VerY Diag and PCR coupled with High-Resolution Melt (HRM) analysis. Parametrical tests (ANOVA) were used to compare the mean Packed cell Volume (PCV) and trypanosomes occurrence. The Cohen Kappa test was used to compare the level of agreement between the diagnostic methods. Findings The overall prevalence of trypanosome infections was 5.6%, 7.1% and 18.7% by thin smear, Buffy coat technique and PCR/HRM respectively. Microscopy showed a low sensitivity while a low specificity was shown by the rapid test (VerY Diag). Trypanosoma (T.) congolense was found at a prevalence of 10.7%, T. vivax 5.2%, T. brucei brucei 2% and T. evansi 0.7% by PCR/HRM. This is the first report of T.evansi in cattle in Rwanda. The non-pathogenic T. theileri was also detected. Lower trypanosome infections were observed in Ankole x Friesian breeds than indigenous Ankole. No human-infective T. brucei rhodesiense was detected. There was no significant difference between the mean PCV of infected and non-infected animals (p>0.162). Conclusions Our study sheds light on the species of animal infective trypanosomes around the Akagera NP, including both pathogenic and non-pathogenic trypanosomes. The PCV estimation is not always an indication of trypanosome infection and the mechanical transmission should not be overlooked. The study confirms that the area around the Akagera NP is affected by AAT, and should, therefore, be targeted by the control activities. AAT impact assessment on cattle production and information on the use of trypanocides are needed to help policymakers prioritise target areas and optimize intervention strategies. Ultimately, these studies will allow Rwanda to advance in the Progressive Control Pathway (PCP) to reduce or eliminate the burden of AAT.

BackgroundGlossina (Tsetse flies) biologically transmit trypanosomes that infect both humans and animals. Knowledge of their distribution patterns is a key element to better understand the transmission dynamics of trypanosomosis. Tsetse distribution in Rwanda has not been well enough documented and little is known of their current distribution. This study determined the current spatial distribution, abundance, diversity, and seasonal variations of tsetse flies in and around the Akagera National Park.MethodsA longitudinal stratified sampling, following the seasons was used. Biconical traps were deployed in 55 sites for six consecutive days of each study month from May 2018 to June 2019, and emptied every 48hours. Flies were identified using FAO keys and the number of flies per trap day (FTD) was used to determine the apparent density. Pearson chi-square (χ2) and parametrical tests (t-test and ANOVA) were used to determine the variations between the variables. The significance (p< 0.05) at 95% confidence interval was considered. Logistic regression was used to determine the association between tsetse occurrence and the associated predictors. Results39,516 tsetse flies were collected, of which 73.4% and 26.6% were from inside Akagera NP and the interface area respectively. Female flies accounted for 61.3% while 38.7% were males. Two species were identified, i.e. G. pallidipes [n=29,121, 7.4 flies/trap/day (FTD)] and G. morsitans centralis (n=10,395; 2.6 FTD). The statistical difference in numbers was significant between the two species (p=0.000). The flies were more abundant during the wet season (15.8 FTD) than the dry season (4.2 FTD). Large numbers of flies were trapped around the swamp areas (69.1 FTD) inside the park and in Nyagatare District (11.2 FTD) at the interface. Glossina morsitans was 0.218 times less likely to occur outside the park. The chance of co-existing between the two species reduced outside the protected area (0.021 times).ConclusionsThe occurrence of Glossina seems to be limited to the protected Akagera NP and a narrow band in its surroundings. This finding will be crucial to design appropriate control strategies. Glossina pallidipes was found in higher numbers and therefore conceivably the most important vector of trypanosomosis. Regional coordinated control and regular monitoring of Glossina distribution are recommended.

Background: Brucellosis and bovine tuberculosis are endemic in Rwandan cattle, but little is known about the awareness of zoonotic transmission and occupational exposure among abattoir workers. Methods: A cross-sectional study was conducted to investigate the awareness, practices, and history of the diseases among 100 abattoir workers from four high throughput and 18 workers from two low throughput abattoirs. Data were collected by face-to-face interviews using a questionnaire, and exposure and outcome variables were assessed by univariate and correspondence analyses.Results: It was found that 82.2%, 27.1%, 8.5%, 10.2%, and 12.7% of abattoir workers were familiar with tuberculosis, brucellosis, Q-fever, leptospirosis, and cysticercosis, respectively. Three years before the survey, the majority (67.8%) of abattoir workers reported sickness of malaria (48.3%), and symptoms of flu (5.1%), headache (5.1%), fever (5.1%), headache (5.1%), and nephritis (3.4%). Malaria-negative patients had the symptoms of fatigue (11.0%), and flu (9.3%). Respondents (7.6%) had contracted ‘abattoir-related diseases including typhoid (1.7%) and have had symptoms of diarrhea (5.9%). Few workers also reported abortion (0.9%), and orchitis (0.9%). Most abattoir workers (70.3%) usually cut their hands, a few (9.3%) wore gloves while 39.8% worked with bare and injured hands. Most (74.6%) of workers experienced splashes of animal fluids into their faces while none (0.0%) wore facemasks or safety goggles. Eating at work was observed in 28.0% of abattoir workers. Univariate and correspondence analyses showed that transporters of carcasses, butchers, and workers with 3 years’ experience and above were more likely to get sick than other groups. Conclusions: The awareness that was low for zoonotic brucellosis, Q-fever, leptospirosis, and cysticercosis was supported by not wearing protective equipment’s alerting the competent veterinary authorities to improve biosafety protection in the abattoirs. The awareness for zoonotic brucellosis and tuberculosis was highest in educated workers indicating the need for educating abattoir. Abattoir workers reported the symptoms of fever, fatigue, flu, headache, nephritis, abortion, and orchitis which are common symptoms of brucellosis, leptospirosis, and Q-fever. Abattoirs are key points for the detection of zoonotic infectious diseases; thus, routine sampling and testing of slaughtered animals and abattoir workers are needed for surveillance and control of zoonotic diseases.

Seroprevalence studies showed that brucellosis is prevalent in cattle in Rwanda with no recent study on the characterization of Brucella spp. Therefore, this study aimed to characterize Brucella spp. in seropositive herds of cattle farmed at the wildlife–livestock–human interface. Whole blood samples (n = 118), milk (n = 41), and vaginal swabs (n = 51) were collected from 64 seropositive herds. All samples (n = 210) were inoculated onto modified Centro de Investigacion y Tecnologia Agroalimentaria (CITA) selective medium. Cultures were analyzed to detect Brucella spp. using 16S−23S ribosomal DNA interspacer region (ITS) PCR, the Brucella cultures were speciated using AMOS and Bruce-ladder PCR assays. Brucella spp. were detected in 16.7% (35/210) of the samples established from the samples using ITS-PCR. The AMOS PCR assay identified mixed Brucella abortus and B. melitensis (n = 6), B. abortus (n = 7), and B. melitensis (n = 1) from cultures from blood samples; mixed B. abortus and B. melitensis (n = 1) and B. abortus (n = 4) from cultures from milk samples; mixed B. abortus and B. melitensis (n = 6), B. abortus (n = 8), and B. melitensis (n = 1) from cultures from vaginal swabs. Bruce-ladder PCR assay confirmed B. abortus and B. melitensis cultures. The isolation of Brucella spp. was significantly associated with districts, with the Nyagatare district having more isolates than other districts (p = 0.01). This study identified single or mixed B. abortus and B. melitensis infections in cattle samples in Rwanda, which emphasizes the need to improve brucellosis control at the wildlife–livestock–human interface and raise the awareness of cattle keepers, abattoir workers, laboratory personnel, and consumers of cattle products.