Epidemiology of Trypanosoma evansi infection in crossbred dairy cattle in Malaysia

The molecular prevalence, distribution and risk factors associated with Babesia bigemina infection in Peninsular Malaysia

Babesia bigemina is a tick-borne protozoan that affects cattle in almost all regions of the world. Despite its importance, there is no report of its prevalence in cattle using molecular detection methods in Peninsular Malaysia. This study describes the prevalence, distribution, and risk factors associated with B. bigemina infection using molecular diagnostic methods. Also, the species of ticks infesting cattle and the attitude of cattle farmers towards tick control in Peninsular Malaysia were studied. Blood samples were collected from 1045 cattle from 43 herds throughout the country, and were subjected to molecular studies to detect B. bigemina. Tick samples for entomological studies were also collected and identified. Epidemiological information of each cattle and farm were obtained using a well-structured questionnaire containing open-ended and closed-ended questions. Data were statistically analyzed using Univariate and Multivariate models. The 211-base pair of AMA-1 gene of B. bigemina was amplified and confirmed in 30.5 % (319/1045; 95 % CI = 27.8-33.4) of the sampled population, with the haemoprotozoan detected in all the sampled herds. Breed, age, physiological status, management type, rate of de-ticking, and closeness to human settlement were the risk factors significantly (p < 0.05) associated with the prevalence of B. bigemina in cattle. Rhipicephalus (Boophilus) microplus and Haemaphysalis bispinosa were the species of ticks collected from cattle, with the former been more prevalent. A large number of cattle farmers (12/43; 28 %) do not control ticks in their herds. The findings of this study will create baseline data on the epidemiology of the haemoprotozoan and control patterns of its tick vectors that will guide the government in enacting policies that will improve food security and the economy of the nation.

First case report on the occurrence of Trypanosoma evansi in a Siam B Mare in Kelantan, Malaysia

This is the first case report for the positive Trypanosoma evansi incident in Kelantan, Malaysia confirmed through protozoa detection in a Siam B mare. The horse was presented with complaints of lethargy and inappetence and it collapsed on the day of visit. Normal saline and dextrose solution were administered intravenously, while multivitamins and nerve supplements were given intramuscularly to stabilise the horse before further treatment. Haematological findings showed normocytic hypochromic anaemia and are suggestive of regenerative anaemia. Thin blood smear and examination revealed the presence of Trypanosoma sp., and it was confirmed as T. evansi through molecular identification. The horse was found dead 2 days after and post-mortem was conducted. Histopathology revealed that the horse had developed a neurological form of the disease, besides the detection of the protozoa in heart, spleen and kidney tissue. This first positive Surra case in Kelantan, Malaysia, that is bordering Thailand confirms the increasing concern of transboundary infections. In conclusion, Surra is a potential emerging disease and should be considered as differential diagnosis in horses with pale mucous membrane. This condition is particularly imperative in horses found in these regions as Surra is endemic.

Molecular Prevalence and Epidemiology of Trypanosoma evansi Among Cattle in Peninsular Malaysia

BACKGROUND

Animal trypanosomiasis (Surra) caused by Trypanosoma evansi (T. evansi) is known to be one of the important haemoprotozoan parasites that causes great economical loss on animal production due to mortality and loss of condition.

METHODS

A cross-sectional study was designed to evaluate the prevalence and risk factors associated with T. evansi infection among cattle in Peninsular Malaysia. Polymerase chain reaction (PCR) was employed on 1045 blood samples collected from 43 farms. A well-structured questionnaire was used to collect data on risk factors associated with T. evansi prevalence. The RoTat 1.2 set of primers was used to amplify products of 205 base pair.

RESULTS

The overall prevalence was found to be 17.9% (187/1045; 95% CI = 15.66-20.31). Trypanosoma evansi was detected among cattle in all the States of Peninsular Malaysia. Breeds of cattle and closeness to waste area, where the risk factors significantly (p < 0.05) associated with the PCR positivity of T. evansi among cattle in Peninsular Malaysia.

CONCLUSION

This appears to be the first time a comprehensive survey on the prevalence and risk factors of T. evansi infection in cattle using molecular tools is been carried out in the entire states of Peninsular Malaysia. The findings from this study will provide baseline information on the molecular prevalence of the haemoflagellate and its associated risk factors among cattle for an improved beef and dairy production in Peninsular Malaysia.

An Epidemiological Review on Emerging and Re-Emerging Parasitic Infectious Diseases in Malaysia

Emerging infectious diseases are infections that have recently appeared in a population over a defined period of time whereas, re-emerging infectious diseases are those that were once a health problem in a particular region or a country and are now emerging again. Parasitic infectious diseases represent a serious health problem in many developing countries and recently have started spreading to developed nations via international traveling or immigration. Malaysia is facing many challenges caused by various parasitic pathogens. The lack of awareness among disadvantaged populations such as the Orang Asli community and the dependency on foreign workers has led to an influx of immigrants to Malaysia from countries endemic to various parasitic diseases. Understanding the social and economic dynamics of such diseases can help anticipate and subsequently control their emergence. Raising public awareness, developing robust public health infrastructure and implementing point-of-care diagnostics will help curb the spread of such diseases. This review provides epidemiological insights into the reported emerging and re-emerging parasitic infectious diseases in Malaysia over the past two decades.

Trypanosoma evansi and surra: a review and perspectives on transmission, epidemiology and control, impact, and zoonotic aspects

This paper reviews the transmission modes of Trypanosoma evansi. Its worldwide distribution is attributed to mechanical transmission. While the role of tabanids is clear, we raise questions on the relative role of Haematobia sp. and the possible role of Stomoxys sp. in delayed transmission. A review of the available trypanocidal drugs and their efficacy in various host species is useful for understanding how they interact in disease epidemiology, which is complex. Although there are similarities with other mechanically transmitted trypanosomes, T. evansi has a more complex epidemiology due to the diversity of its hosts and vectors. The impact of clinical and subclinical disease is difficult to establish. A model was developed for buffaloes in the Philippines, which could be transferred to other places and livestock systems. Since Trypanosoma evansi was reported in humans, further research is required to investigate its zoonotic potential. Surra remains a potentially emerging disease that is a threat to Australia, Spain, and France. A number of questions about the disease have yet to be resolved. This brief review of the basic knowledge of T. evansi suggests that there is renewed interest in the parasite, which is spreading and has a major economic impact.

Surveys in Papua New Guinea to detect the presence of Trypanosoma evansi infection

OBJECTIVE

To confirm serological evidence that Trypanosoma evansi is present in Papua New Guinea.

DESIGN

Three surveys were undertaken in PNG during 1997/1998. Animals were selected for sampling on the basis of convenience. Samples of blood were examined for the presence of T evansi by the haematocrit centrifugation technique (HCT) and mouse inoculation test (MI). Sera were tested in the field using the card agglutination test for trypanosomiasis/T evansi (CATT). Bovine sera were tested at James Cook University using an antibody-detection ELISA (Ab-ELISA). Results from testing bovine sera with the Ab-ELISA and sera from wallabies with the CATT were analysed using FreeCalc to determine the probability that animals in these populations were infected with T evansi.

RESULTS

A total of 545 serum samples were collected, during the three surveys of which 39 cattle, two pig and three agile wallaby samples were positive with the CATT. All bovine sera collected were negative when tested with an Ab-ELISA. T evansi was not isolated using the HCT or the MI from any of these animals.

CONCLUSION

Based on the Ab-ELISA results it was concluded that T evansi infection was not present in cattle in villages around Balimo at a minimum expected prevalence of 10% (P < 0.05) and, based on the CATT results, that infection was not present in wallabies on the Bula plain at a minimum expected prevalence of 10% (P < 0.1). These results indicate that it is unlikely that T evansi is endemic in PNG.