Ehrlichiosis in dogs is an emerging vector borne rickettsial zoonotic disease of worldwide distribution. In general, three Ehrlichial species (Ehrlichia canis, E. ewingii, and E. chaffeensis) are involved in infecting dogs. Among them, E. canis is the well-known etiological pathogen affecting platelets, monocytes, and granulocytes. Dogs act as a reservoir, while the main vector responsible for disease transmission is Rhipicephalus sanguineus. However, in east Asian countries, Haemaphysalis longicornis is considered the principal vector for disease transmission. This disease affects multiple organs and systems and has three clinical manifestations, including acute, subclinical, and chronic. Definitive diagnosis involves visualization of morulae on cytology, detection of antibodies through an indirect immunofluorescence test (IFAT), and DNA amplification by polymerase chain reaction (PCR). In canine ehrlichiosis, no predilection of age or sex is observed; however, Siberian Huskies and German Shepherds are more likely to develop severe clinical manifestations. Doxycycline, rifampicin, and minocycline are proven to be effective drugs against canine ehrlichiosis. This review is intended to describe a brief overview of Ehrlichia infection in dogs, its reported prevalence in east and south Asian countries, and the latest knowledge regarding chemotherapy and associated vectors responsible for the disease transmission. This manuscript also identifies the prevailing knowledge gaps which merit further attention by the scientific community.

Marek’s disease is an infectious disease in poultry that usually appears in neural and visceral tumors. This disease is caused by Gallid alphaherpesvirus 2 infection in lymphocytes, and its meq gene is commonly used in virulent studies for coding the key protein functional in oncogenic transformation of the lymphocytes. Although vaccines have been introduced in many countries to control its spread and are proven to be efficient, recent records show a decline of such efficiency due to viral evolution. In this study, we reviewed the outbreak of Marek’s disease in Asia for the last 10 years, together with associated meq sequences, finding a total of 36 studies recording outbreaks with 132 viral strains in 12 countries. The visceral type is the most common (13 in 16 studies) form of Marek’s disease, but additional unobserved neural changes may exist. MD induces liver lymphoma most frequently (11 in 14 studies), and tumors were also found in spleen, kidney, heart, gizzard, skin, intestine, lung, and sciatic nerve. Twelve viral strains distributed in China have been reported to escape the CVI988 vaccine, reaching a mortality rate of more than 30%. Phylogenetic analyses show the internal connection between the Middle East (Turkey, Iraq, Iran, Saudi Arabia), South Asia (India, Indonesia), and East Asia (China and Japan), while external viral communications might occasionally occur. In 18 strains with both sequential and mortality data, amino acid alignment showed several point substitutions that may be related to its virulence. We suggest more behavioral monitoring in Marek’s disease-endemic regions and further studies on strain virulence, together with its Meq protein structural changes.

Tropical theileriosis, caused by the apicomplexan hemoparasite of the genus Theileria, is a major constraint to livestock production in various parts of world, including South Asia. Several studies have been carried out over the last five decades; however, comprehensive information in this region regarding the diversity and distribution of Theileria is lacking. Therefore, keeping in mind the economic importance of theileriosis, we have systematically reviewed the current knowledge about Theileria spp. diversity and distribution affecting cattle, water buffaloes, goats and sheep in three countries included India, Pakistan and Bangladesh of the Indian sub-continent. The data collected indicated that the microscopic method is the widely used method for evaluating Theileria species in the three countries from 1970 to 2021. This is the first study in this region to compile a comprehensive knowledge about the diversity and distribution of Theileria. Our study revealed the existence of 11 different species of Theileria, including Theileria spp. Theleria annulata, T. orientalis, T. mutans, T. velifera circulating in cattle and buffalo while T. annulata, T. lestoquardi, T. luwenshuniT. ovis, Theileria spp. and T. lestoquardi-like spp., were infecting goats and sheep from various regions of India, Pakistan and Bangladesh. We find that T. annulata can be found in both small and large ruminants and is widely distributed in the different regions of India, Pakistan and Bangladesh. In addition, our analysis revealed that the existence of possible tick vectors of the genera Hyalomma, Haemophysalis, Rhipicephalus and Amblyomma may be responsible for the diverse and wide distribution of different Theileria species. However, the competence of these tick vectors for different Theileria species still need to be explored. Therefore, further studies are needed to bridge this gap and to improve the health and production of livestock and reduce economic losses due to theileriosis in India, Pakistan and Bangladesh. Furthermore, we selected representative 18S rRNA sequences for T. annulata from the different regions to infer phylogenetic relationship. Phylogenetic analysis of the selected isolates clustered in different clades which might be due to the variation in a hypervariable region of 18S rRNA. The outcome of this analysis is expected to provide a coherent and integrated framework about the different Theileria species prevailing in these countries and contribute to improving the surveillance and control plans of various Theileria species in the region.

Zoonotic babesiosis poses a serious health risk in many parts of the world. Its emergence in Asia is thus a cause for significant concern, demanding that appropriate control measures are implemented to suppress its spread in this region. This study focuses on zoonotic Babesia species reported in Asia, offering an extensive review of those species reported in animals and humans. We reported 11 studies finding zoonotic Babesia species in animals and 16 in humans. In China, the most prevalent species was found to be Babesia microti, reported in both humans (n = 10) and wild and domesticated animals (n = 4). In Korea, only two studies reported human babesiosis, with a further two studies reporting Babesia microti in wild animals. Babesia microti was also reported in wild animal populations in Thailand and Japan, with evidence of human case reports also found in Singapore, Mongolia and India. This is the first review to report zoonotic babesiosis in humans and animals in Asia, highlighting concerns for future public health in this region. Further investigations of zoonotic species of Babesia in animal populations are required to confirm the actual zoonotic threat of babesiosis in Asia, as well as its possible transmission routes.

Background: Vector-/tick-borne pathogens (V/TBPs) pose a potential threat to human and animal health globally. Information regarding canine V/TBPs is scarce and no specific study has been conducted so far to explore the microbial diversity within ticks infesting dogs from Pakistan. Herein, this knowledge gap is addressed by assessing the genetic diversity and prevalence pattern of V/TBPs in ixodid ticks with special implications for public and canine health.Methods: A total of 1150 hard ticks were collected from 300 dogs across central Khyber Pakhtunkhwa (KP), Pakistan. After morpho-molecular identification, 120 tick samples were screened for the presence of V/TBPs by amplifying16S rRNA/gltA(Rickettsia/EhrlichiaandWolbachiasp.),18S rRNA(Theileriasp.) andcox1(Dirofilariasp.) genes through PCR followed by sequencing and phylogenetic study.Results: In toto, 50 ixodid ticks (50/120, 41.7%) were found positive for V/TBPs DNA. The detected V/TBPs were categorized into five genera and eight species, viz.Ehrlichia(E. canisandEhrlichiasp.),Rickettsia(R. massiliae, R. raoultiiandRickettsiasp.),Theileria(T. annulata),Dirofilaria(D. immitis) andWolbachia(Wolbachiasp.). The pathogen prevalence patterns showed thatR. massiliaewas the most prevalent zoonotic V/TBP (19.5%), followed byE. canis(10.8%),Rickettsiasp. (7.5%), R. raoultii(6.7%),T. annulata(5.8%),D. immitis(5.8%),Wolbachiasp. (4.2%) andEhrlichiasp. (3.3%), respectively. Among the screened tick species, mostRhipicephalus sanguineussensu lato samples were found positive for V/TBP DNA (20/20,100%) followed byRh. turanicussensu stricto (13/20, 65%),Hyalomma dromedarii(8/20, 40%),Rh. haemaphysaloides(6/20, 30%),Hy. excavatum(2/20, 10%) andRh. microplus(1/20, 5%). Co-occurrence of V/TBP was also detected in tick specimens (single V/TBP infection: 32 ticks; double and triple: 13 and 5 tick samples). The detected pathogens shared a phylogenetic relationship with similar isolates published in NCBI GenBank from Old and New World countries.Conclusion: Ixodid ticks infesting dogs harbor a diverse array of V/TBPs including zoonotic agents from Pakistan. Furthermore, the presence ofD. immitisin ticks that infest dogs raises the possibility that this parasite has either attained its dead-end host (i.e. the tick) while feeding on dogs or has expanded its range of intermediate/paratenic hosts. Further research work is needed to investigate the epidemiology and confirm the vector competence of screened tick species for these pathogens from Pakistan.Graphical

Ticks and tick-borne diseases are considered a major challenge for human and animal health in tropical, sub-tropical, and temperate regions of the world. However, only scarce information is available on the characterization of tick species infesting dogs in Pakistan. In this study, we present a comprehensive report on the epidemiological and phylogenetic aspects of ticks infesting dogs in Pakistan using the mitochondrial markers i.e. Cytochrome c oxidase subunit 1 (cox1) and 16S ribosomal RNA (16S rRNA) nucleotide sequences. A total of 300 dogs were examined and 1150 ixodid ticks were collected across central Khyber Pakhtunkhwa, Pakistan. The morpho-molecular characterization of hard ticks revealed the presence of two ixodid tick genera on dogs, i.e., Hyalomma and Rhipicephalus, including six tick species viz. Hyalomma dromedarii (15.9%), Hyalomma excavatum (3%), Rhipicephalus sanguineus s.l. (41.3%), Rhipicephalus turanicus s.s. (28.7%), Rhipicephalus haemaphysaloides (10.2%), and Rhipicephalus microplus (2%). The total prevalence of tick infestation in dogs was 61%. The district with the highest tick prevalence rate in dogs was Mardan (14.7%), followed by Peshawar (13%), Swabi (12%), Charsadda (11%), and Malakand (10.3%), respectively. Risk factors analysis indicated that some demographic and host management-associated factors such as host age, breed, exposure to acaricides treatment, and previous tick infestation history were associated with a higher risk of tick infestation on dogs. This is the first molecular report confirming the infestation of Hyalomma and Rhipicephalus tick species in the dog population from the study area. The present study also reported a new tick–host association between Hy. excavatum, Hy. dromedarii, and dogs. Phylogenetic analysis revealed that cox1 partial nucleotide sequences of Hy. excavatum in our dataset were 100% identical to similar tick specimens identified in Turkey, and those of Hy. dromedarii were identical to tick specimens from Iran. Whereas, Rh. haemaphysaloides and Rh. microplus’ cox1 partial nucleotide sequences were identical to sequences previously published from Pakistan. Rhipicephalus turanicus s.s. ‘s cox1 isolates from the present study were 99.8–100% identical to Pakistani-reported isolates, and those of Rh. sanguineus s.l. were 100% identical to Chinese specimens. Results on the genetic characterization of ticks were further confirmed by 16S rRNA partial nucleotide sequences analysis, which revealed 100% identity between the tick isolates of this study and those of Hy. excavatum reported from Turkey; Hy. dromedarii specimens reported from Senegal; Rh. haemaphysaloides, Rh. microplus, and Rh. turanicus s.s., previously published from Pakistan, and Rh. sanguineus s.l., published from China. Furthermore, phylogenetic analysis showed that the Rh. sanguineus s.l. isolates of this study clustered with specimens of the tropical lineage with 7.7–10% nucleotide divergence from the specimens of the temperate lineage. Further molecular works need to be performed throughout Pakistan to present a more detailed map of tick distribution with information about dog host associations, biological characteristics, and pathogen competence.