Comparison of Light Microscopy and Polymerase Chain Reaction for the Detection of Haemoparasites in Cattle in Nigeria

Tick-Borne Diseases in Sub-Saharan Africa: A Systematic Review of Pathogens, Research Focus, and Implications for Public Health

Sub-Saharan Africa, with its hot and humid climate, is a conducive zone for tick proliferation. These vectors pose a major challenge to both animal and human health in the region. However, despite the relevance of emerging diseases and evidence of tick-borne disease emergence, very few studies have been dedicated to investigating zoonotic pathogens transmitted by ticks in this area. To raise awareness of the risks of tick-borne zoonotic diseases in sub-Saharan Africa, and to define a direction for future research, this systematic review considers the trends of research on tick-borne bacteria, parasites, and viruses from 2012 to 2023, aiming to highlight the circulation of these pathogens in ticks, cattle, sheep, goats, and humans. For this purpose, three international databases were screened to select 159 papers fitting designed inclusion criteria and used for qualitative analyses. Analysis of these studies revealed a high diversity of tick-borne pathogens in sub-Saharan Africa, with a total of 37 bacterial species, 27 parasite species, and 14 viruses identified. Among these, 27% were zoonotic pathogens, yet only 11 studies investigated their presence in humans. Furthermore, there is growing interest in the investigation of bacteria and parasites in both ticks and ruminants. However, research into viruses is limited and has only received notable interest from 2021 onwards. While studies on the detection of bacteria, including those of medical interest, have focused on ticks, little consideration has been given to these vectors in studies of parasites circulation. Regarding the limited focus on zoonotic pathogens transmitted by ticks, particularly in humans, despite documented cases of emerging zoonoses and the notable 27% proportion reported, further efforts should be made to fill these gaps. Future studies should prioritize the investigation of zoonotic pathogens, especially viruses, which represent the primary emerging threats, by adopting a One Health approach. This will enhance the understanding of their circulation and impact on both human and animal health. In addition, more attention should be given to the risk factors/drivers associated to their emergence as well as the perception of the population at risk of infection from these zoonotic pathogens.

Molecular Detection of Hemoplasma in animals in Tamil Nadu, India and Hemoplasma genome analysis

Hemoplasma are small pleomorphic wall-less Gram-positive bacteria that infect erythrocytes of various mammalian hosts. They generally cause asymptomatic or chronic anaemia but occasionally causes overt life-threatening hemolytic anaemia. In the present study, 316 cattle, 115 sheep, 61 goats and 6 buffalo blood samples were collected from various villages or organized farms located in nine districts of Tamil Nadu to detect the hemoplasma by PCR. Overall prevalence of 43.04%, 65.22%, and 44.26% hemoplasma DNA was observed in cattle, sheep and goats, respectively. In total, 21 hemoplasma positive samples were sequenced for 16S rRNA gene which revealed 8 Mycoplasma wenyonii, 11 'Candidatus Mycoplasma haemobos' and one Mycoplasma ovis infection. Sheep blood samples from Chennai district were infected with 'Ca. M. haemobos' whereas sheep sample from Thiruvannamalai district was infected with M. wenyonii. At least 50% genes in the hemoplasma genomes were paralogous genes whose functions were not known. Only 'Ca. M. haemolamae' genome contained one primitive CRISPR system without any cas genes. Antimicrobial resistance genes (ARG) could not be identified in any of the hemoplasma genomes but homologous ARG were identified in all the genomes. Adhesion related gene EF-Tu was detected in all 14 hemoplasma genomes but enolase gene was detected only in 'Ca. M. haemohominis' SWG34-3 genome. This is the first report on the prevalence of hemoplasma infection in cattle, sheep and goat in India.

Preliminary report of Mycoplasma Wenoynii and Candidatus Mycoplasma haemobos infection in Korean native cattle

BACKGROUND

Hemotropic mycoplasmas or hemoplasmas are bacteria that attach to the erythrocyte surface and cause bovine hemoplasmosis. Two species, Mycoplasma wenyonii and Candidatus Mycoplasma haemobos, have been identified and shown to be distributed worldwide. However, there is currently no information available on hemoplasmas in cattle in the Republic of Korea. The aim of this study was to investigate the presence of hemoplasmas in Korean native cattle and to evaluate the association between hemoplasma infection and anemia.

METHODS

One farm was selected, at which blood samples were collected from 104 Korean native cattle [grazing cattle (n = 89) and housed cattle (n = 15)]. Hemoplasmas were detected via polymerase chain reaction analysis and complete blood counts were also performed.

RESULTS

The overall prevalence of hemoplasmas was 34% (35/104); 20.2% (21/104) for M. wenyonii, 3.8% (4/104) for C. M. haemobos, and 9.6% (10/104) for co-infection. Candidatus Mycoplasma haemobos was detected only in grazing cattle. Of red blood cell (RBC) parameters, C. M. haemobos-infected cattle had lower RBC and hematocrit, and higher mean cell volume than hemoplasma-negative cattle, although none of these differences were statistically significant. This is the first study to report the occurrence of M. wenyonii and C. M. haemobos. Mycoplasma wenyonii is more prevalent than C. M. haemobos in Korean native cattle. The results did not show an association between hemoplasma infection and anemia.

CONCLUSIONS

Considering the infection rate of hemoplasmas shown in this study, further studies, such as on the pathogenicity and clinical significance of hemoplasmas are necessary.

Tick-borne pathogens in camels: A systematic review and meta-analysis of the prevalence in dromedaries

Published data on tick-borne pathogens (TBPs) in camels worldwide have been collected to provide an overview of the global prevalence and species diversity of camelid TBPs. Several TBPs have been detected in dromedary camels, raising concerns regarding their role as natural or maintenance hosts for tick-borne pathogens. Insubstantial evidence exists regarding the natural infection of camels with Babesia spp., Theileria spp., Anaplasma spp., and Ehrlichia spp., particularly because most of the camels were considered healthy at the time of sampling. Based on polymerase chain reaction (PCR) testing, a pooled prevalence of 35.3% (95% CI: 22.6-48.1%) was estimated for Anaplasma, which was the most frequently tested TBP in dromedaries, and DNA of Anaplasma marginale, Anaplasma centrale, Anaplasma ovis, Anaplasma platys, and A. platys-like were isolated, of which ruminants and dogs are reservoirs. Similarly, the estimated pooled prevalence for the two piroplasmid genera; Babesia and Theileria was approximately equal (10-12%) regardless of the detection method (microscopy or PCR testing). Nevertheless, Babesia caballi, Theileria equi, and Theileria annulata DNA have frequently been detected in camels but they have not yet been proven to be natural hosts. Scarce data detected Babesia microti, Anaplasma phagocytophilum, and Borrelia burgdorferi sensu lato (s.l.) DNA in blood of dromedaries, although ticks of the genus Ixodes are distributed in limited areas where dromedaries are raised. Interestingly, a pooled seroprevalence of 47.7% (26.3-69.2%) was estimated for Crimean-Congo hemorrhagic fever virus, and viral RNA was detected in dromedary blood; however, their contribution to maintain the viral transmission cycles requires further experimental investigation. The substantially low incidence and scarcity of data on Rickettsia and Ehrlichia species could imply that camels were accidentally infected. In contrast, camels may play a role in the spread of Coxiella burnetii, which is primarily transmitted through the inhalation of aerosols emitted by diseased animals and contaminated environments. Bactrian camels showed no symptoms due to the examined TBPs, meanwhile, clinical disease was seen in alpacas infected with A. phagocytophilum. Similar to dromedaries, accidental tick bites may be the cause of TBP DNA found in the blood of Bactrian camels.

Mycoplasma wenyonii and Candidatus Mycoplasma Haemobos in Pastoralists Cattle in Nigeria

PURPOSE

The extensive migration practiced by pastoralists cattle exposes them to a variety of pathogens and vectors which may sometimes lead to severe disease outcomes. Moreover, the synergistic effect of multiple parasitism on the productivity of livestock has been well recognized. This is particularly true where the livestock production system predisposes the animals to constant and heavy infestation with arthropod vectors.

METHODS

The presences, prevalence and risk factors for hemotropic Mycoplasma (hemoplasma) infection in cattle in Nigeria was investigated using a PCR and sequencing approach. DNA, extracted from 566 cattle blood samples, collected from 10 states from the three agro-ecological zones (AEZs) of Nigeria, from April 2021 to March 2022, were screened for the presences of hemotropic Mycoplasma spp. DNA.

RESULTS

The DNA of hemoplasmas was detected in 48 out of the 566 (8.5%) samples, 12 (25%) of them were identified as Mycoplasma wenyonii and 19 (38.6%) as 'Candidatus Mycoplasma haemobos'. Coinfection with both species was detected in 17 (35.4%) of the samples. High prevalence and risk of hemoplasmas infection was associated with sex of the cattle (bulls were more affected; p = 0.005) and the packed cell volume (p = 0.009), but not with the age (p = 0.08), breed (p = 0.22), body condition (p = 0.052), source of the samples (p = 0.45) or the AEZs (0.59). This is the first nationwide survey of hemotropic mycoplasmas in cattle in Nigeria using this molecular approach.

CONCLUSION

Further studies to determine the veterinary and public health significance of these pathogens, which were previously associated with varying degrees of clinical signs and production losses, are recommended in Nigerian cattle.

Abortion outbreak in pregnant goats and cows with coinfection of 'Candidatus Mycoplasma haemobos' and HoBi-like pestivirus

New emerging diseases, including 'Candidatus Mycoplasma haemobos' ('Ca. M. haemobos') and HoBi-like pestivirus in central China has been a huge challenge for ruminant production. From July to September 2022, an abortion outbreak affected 14 goat farms and 11 cattle farms in this area. To investigate whether the two pathogens are associated with the disease, samples were collected: Group 1 included 55 goat blood samples with foetal tissue samples and ticks on the skin; Group 2 included nine healthy goat blood samples; Group 3 included 36 cow blood samples with foetal tissue samples and ticks on the skin; and Group 4 included seven healthy cow blood samples. Then, these samples were analysed by serology, PCR, sequence analysis, and identification. A total of 339 Rhipicephalus (Boophilus) microplus and 61 Haemaphysalis longicornis ticks were identified in Group 1 and Group 3. By molecular detection, 32 'Ca. M. haemobos'-positive amplicons, and 27 HoBi-like pestivirus-positive amplicons were amplified from goats in Group 1; meanwhile, 20 'Ca. M. haemobos'-positive amplicons, and 18 HoBi-like pestivirus-positive amplicons were amplified from foetuses. Statistical significance (P = 0.002) and association (OR=7.556) between the 'Ca. M. haemobos' PCR results of foetus and goat samples were observed, and statistical significance (P = 0.017) and association (OR=4.271) between the HoBi-like pestivirus PCR results of foetus and goat samples were observed. These significances and associations were also observed in Group 3. In addition, coinfections were detected in Group 1 and Group 3. 'Ca. M. haemobos' was detected in both tick species. Further serological results revealed that the frequency of HoBi-like pestivirus was 20.0 % (11/55) in Group 1 % and 30.6 % (11/36) in Group 3 in central China. No ticks, pathogens, or neutralizing antibodies were observed in Group 2 or Group 4. This is the first molecular evidence of 'Ca. M. haemobos' and HoBi-like pestivirus natural coinfections in goats and cows with abortion in China. HoBi-like pestivirus and 'Ca. M. haemobos' can be transferred from goats/cows to their foetuses.

Molecular prevalence of tick-borne haemoprotozoan diseases in cattle of North Eastern state of Tripura, India

The tick-borne haemoprotozoan diseases are major constraint in the health and production of cattle and causes substantial losses to the livestock industry throughout the world. Tripura is a northeastern state of India characterized by a warm humid tropical climate and high rainfall which is conducive to the multiplication of vector-ticks of haemoprotozoan diseases. A total of 320 tick-infested cattle (22 male and 298 female) of either sex was selected randomly from different district of Tripura for the detection of carrier cattle infected with tick-borne haemoparasites from July, 2017 to June, 2019. Out of 320 tick-infected cattle, 4.69% prevalence of B. bigemina infection in cattle was found while Theleria spp. was not prevalent in the collected blood sample by using polymerase chain reaction. The prevalence of B. bigemina was significantly (< 0.05) higher in cattle more than 3 years of age (6.72%) compared to the 1-3 years age group (3.97%) and < 1 year age groups (1.66%). Sex-wise B. bigemina infection was significantly (< 0.05) seen only in female (5.03%) cattle infested with ticks. The district-wise B. bigemina prevalence (%) in Tripura was as in cattle; Dhalai (0.63), Sipahijala (0.31), Khowai (0.31), Gomati (0.31), South Tripura (0.63), North Tripura (0.31), Unakoti (0.31) and West Tripura (1.87) respectively. The use of PCR assays for the detection of B. bigemina and Theileria spp. in the North Eastern state of Tripura of India showed prevalence of 4.69% and 0%, respectively in tick-infested cattle. This study is the first report about the prevalence of tick-borne haemoprotozoan diseases from cattle of Tripura and suggest that babesiosis is more common disease as compared to theileriosis and is more prevalent in adult female tick-infested cattle in Tripura.

Molecular detection of haemophilic pathogens reveals evidence of Candidatus Mycoplasma haemobos in dogs and parasitic ticks in central China

Background

In addition to Mycoplasma haemocanis and Candidatus Mycoplasma haematoparvum, a few hemoplasma species that mainly infect other livestock have been detected in dogs. ‘Candidatus Mycoplasma haemobos’ (Ca. M. haemobos) has been found in a variety of animals in China. The present study was aimed to investigate the occurrence of ‘Ca. M. haemobos’ infections in dogs and ticks collected from the Henan province, China.

Results

Overall, 55 dog blood samples and 378 ticks on skins were collected from anemic and healthy dogs, and these samples were subjected to PCR, sequence analysis, and identification. The results showed that Haemaphysalis longicornis (266) and Rhipicephalus (Boophilus) microplus (112) were the only two parasitic ticks on dogs. Molecular detection revealed that 163 M. haemocanis, 88 ‘Ca. M. haemobos’ and 32 Anaplasma platys positive amplicons could be amplified from dogs, H. longicornis and R. (B.) microplus. In addition, co-infections (M. haemocanis + A. platys and ‘Ca. M. haemobos’+ A. platys) could be also detected.

Conclusions

To the best of our knowledge, this is the first molecular evidence of ‘Ca. M. haemobos’ natural infection in dogs and tick species identified as H. longicornis and R. (B.) microplus from China.

Molecular Detection and Identification of Piroplasms in Semi-Intensively Managed Cattle from Abeokuta, Nigeria

Piroplasmosis is a tick-borne haemolytic disease caused by different species of the Babesia and Theileria genera. Data on the prevalence of bovine piroplasms and their genetic diversity are scanty in Nigeria. Hence, this study reported the detection of some piroplasms in the blood of cattle in Abeokuta, Nigeria by the polymerase chain reaction (PCR). Blood samples were collected from 252 cattle and subjected to DNA extraction followed by PCR amplification of the partial region of 18S rRNA of the haemoprotozoans. Selected positive amplicons were unidirectionally sequenced and compared to the reference sequences from the Genbank. A total of 220 (87.3 %) cattle were positive for Theileria velifera and/or Babesia bigemina. The T. velifera was detected only in 163 (64.7 %) cattle, while 7 (2.8 %) cattle had a single infection with B. bigemina. Fifty cattle (19.8 %) had mixed infections with both parasites. There were no significant differences in piroplasm infections between the ages of cattle for both parasites. There were no significant differences in infection rates between the sexes for T. velifera, while the males had a significantly higher (P < 0.05) rate of infection for B. bigemina than the female cattle. The molecular detection of Babesia and Theileria species of cattle are reported for the first time in cattle in Abeokuta, Nigeria. This study, which confirmed the endemic nature of the parasites in cattle in the study area, stresses their importance in livestock health and production in Nigeria.

First Molecular Detection and Characterization of Hemotropic Mycoplasma Species in Cattle and Goats from Uganda

Hemoplasmas (hemotropic mycoplasmas) are small pleomorphic bacteria that parasitize the surface of red blood cells of several mammalian species including cattle, goats, and humans, causing infectious anemia. However, studies on hemoplasmas have been neglected and to date, there are no studies on bovine and caprine hemoplasmas in Uganda or the entire East African region. In this study, a polymerase chain reaction (PCR) assay targeting the 16S rRNA gene was used to investigate the presence of hemoplasma in 409 samples (cattle = 208; goats = 201) collected from Kasese district, western Uganda. Results showed that 32.2% (67/208) of cattle samples and 43.8% (88/201) of goat samples were positive for hemoplasmas. Sequencing analysis identified Candidatus Mycoplasma haemobos and Mycoplasma wenyonii in cattle, while Candidatus Mycoplasma erythrocervae and Mycoplasma ovis were identified in goats. Statistical analysis showed that goats were at a higher risk of infection with hemoplasmas compared with cattle. To the best of our knowledge, this is the first molecular evidence of hemoplasmas in bovine and caprine animals in Uganda and the entire east African region.