Associations between monthly rainfall and mortality in cattle due to East Coast fever, anaplasmosis and babesiosis.

Weather conditions can impact infectious disease transmission, causing mortalities in humans, wild and domestic animals. Although rainfall in dry tropical regions is highly variable over the year, rainfall is thought to play an important role in the transmission of tick-borne diseases. Whether variation in rainfall affects disease-induced mortalities, is, however, poorly understood. Here, we use long-term data on monthly rainfall and Boran cattle mortality (1998-2017) to investigate associations between within-year variation in rainfall and cattle mortalities due to East Coast fever (ECF), anaplasmosis and babesiosis in Laikipia, Kenya, using ARIMAX modelling. Results show a negative correlation between monthly rainfall and cattle mortality for ECF and anaplasmosis, with a lag effect of 2 and 6 months, respectively. There was no association between babesiosis-induced mortalities and monthly rainfall. The results of this study suggest that control of the tick-borne diseases ECF and anaplasmosis to reduce mortalities should be intensified during rainy periods after the respective estimated time lags following dry periods.

Occurrence of tick-borne haemoparasites in cattle in the Mungwi District, Northern Province, Zambia.

Little is known about the occurrence of haemoparasites in cattle in communal grazing areas of Mungwi District of Northern Province, Zambia. Clinical signs and post mortem lesions are pathognomonic of mixed tick-borne infections especially babesiosis, anaplasmosis and East Coast fever. The main objective of this study was to screen selected communal herds of cattle for tick-borne haemoparasites, and identify the tick vectors associated with the high cattle mortalities due to suspected tick-borne diseases in the local breeds of cattle grazing along the banks of the Chambeshi River in Mungwi District, Northern Province, Zambia. A total of 299 cattle blood samples were collected from July to September 2010 from Kapamba (n = 50), Chifulo (n = 102), Chisanga (n = 38), Kowa (n = 95) and Mungwi central (n = 14) in the Mungwi District. A total of 5288 ticks were also collected from the sampled cattle from April to July 2011. DNA was extracted from the cattle blood and the hypervariable region of the parasite small subunit rRNA gene was amplified and subjected to the reverse line blot (RLB) hybridization assay. The results of the RLB assay revealed the presence of tick-borne haemoparasites in 259 (86.6%) cattle blood samples occurring either as single (11.0%) or mixed (75.6%) infections. The most prevalent species present were the benign Theileria mutans (54.5%) and T. velifera (51.5%). Anaplasma marginale (25.7%), Babesia bovis (7.7%) and B. bigemina (3.3%) DNA were also detected in the samples. Only one sample (from Kapamba) tested positive for the presence of T. parva. This was an unexpected finding; also because the tick vector, Rhipicephalus appendiculatus, was identified on animals from Kowa (14.0%), Chisanga (8.5%), Chifulo (6.0%) and Kapamba (1.4%). One sample (from Kapamba) tested positive for the presence of Ehrlichia ruminantium even though Amblyomma variegatum ticks were identified from 52.9% of the sampled animals from all study areas. There was significant positive association between T. mutans and T. velifera (p < 0.001) infections, and between A. marginale and B. bovis (p = 0.005). The presence of R. microplus tick vectors on cattle was significantly associated with B. bovis (odds ratio, OR = 28.4, p < 0.001) and A. marginale (OR = 42.0, p < 0.001) infections, while A. variegatum presence was significantly associated with T. mutans (OR = 213.0, p < 0.001) and T. velifera (OR = 459.0, p < 0.001) infections. Rhipicephalus decoloratus was significantly associated with B. bigemina (OR = 21.6, p = 0.004) and A. marginale (OR = 28.5, p < 0.001). Multivariable analysis showed a significant association between location and tick-borne pathogen status for A. marginale (p < 0.001), T. mutans (p = 0.004), T. velifera (p = 0.003) and T. taurotragi (p = 0.005). The results of our study suggest that the cause of cattle mortalities in Mungwi during the winter outbreaks is mainly due to A. marginale, B. bovis and B. bigemina infections. This was confirmed by the clinical manifestation of the disease in the affected cattle and the tick species identified on the animals. The relatively low prevalence of T. parva, B. bigemina, B. bovis and E. ruminantium could indicate the existence of endemic instability with a pool of susceptible cattle and the occurrence of disease outbreaks.

Human Granulocytic Anaplasmosis as a Cause of Febrile Illness in Korea Since at Least 2006.

AbstractHuman granulocytic anaplasmosis (HGA) is a tick-borne rickettsial zoonosis with fever, thrombocytopenia, and leukopenia. HGA has been reported in Korea in 2013 but it is uncertain how long it has existed. A retrospective study was conducted on patients who underwent bone marrow examination due to fever and cytopenia, with no clear hematologic or microbiologic causes, from 2003 through 2012. Laboratory diagnosis was made by detecting 16S rRNA genes of Anaplasma phagocytophilum from the stored blood samples. Among the 70 patients, five (7.1%) HGA cases were found, and the earliest case dated back to 2006. Two cases met the diagnostic criteria of hemophagocytic lymphohistiocytosis (HLH) and were fatal. Although HGA has been prevalent in Korea since at least 2006, it is not always diagnosed and has posed a possible lethal health risk to the people in Korea. HGA should be considered as a cause of fever with cytopenia or HLH.

Estimated direct economic costs associated with tick-borne diseases on cattle in Tanzania.

Tick-borne diseases, namely, anaplasmosis, babesiosis, cowdriosis and theileriosis, constrain cattle production and improvement in Tanzania, leading to considerable economic losses. A simple spreadsheet model was used to estimate the economic losses resulting from production losses, treatment and control costs associated with tick-borne diseases (TBD) in Tanzania. Model parameters included the national cattle population, reported TBD morbidity, fatality risk, and chemotherapy and control measures used. The total annual national loss due TBD was estimated to be 364 million USD, including an estimated mortality of 1.3 million cattle. Theileriosis accounted for 68% of the total loss, while anaplasmosis and babesiosis each accounted for 13% and cowdriosis accounted for 6% of the total loss. Costs associated with mortality, chemotherapy and acaricide application accounted for 49%, 21% and 14% of the total estimated annual TBD losses, respectively, infection and treatment method milk loss and weight loss accounted for 1%, 6% and 9% of the total annual loss, respectively. Despite the inadequacies of the data used, the results give evidence that tick-borne diseases inflict substantial economic losses on cattle production and resource use in Tanzania.

Concurrent infections with vector-borne pathogens associated with fatal hemolytic anemia in a cattle herd in Switzerland.

Bovine anaplasmosis is a vector-borne disease that results in substantial economic losses in other parts of the world but so far not in northern Europe. In August 2002, a fatal disease outbreak was reported in a large dairy herd in the Swiss canton of Grisons. Diseased animals experienced fever, anorexia, agalactia, and depression. Anemia, ectoparasite infestation, and, occasionally, hemoglobinuria were observed. To determine the roles of vector-borne pathogens and to characterize the disease, blood samples were collected from all 286 animals: 50% of the cows were anemic. Upon microscopic examination of red blood cells, Anaplasma marginale inclusion bodies were found in 47% of the cows. The infection was confirmed serologically and by molecular methods. Interestingly, we also found evidence of infections with Anaplasma phagocytophilum, large Babesia and Theileria spp., and Mycoplasma wenyonii. The last two species had not previously been described in Switzerland. Anemia was significantly associated with the presence of the infectious agents detected, with the exception of A. phagocytophilum. Remarkably, concurrent infections with up to five infectious vector-borne agents were detected in 90% of the ill animals tested by PCR. We concluded that A. marginale was the major cause of the hemolytic anemia, while coinfections with other agents exacerbated the disease. This was the first severe disease outbreak associated with concurrent infections with vector-borne pathogens in alpine Switzerland; it was presumably curtailed by culling of the entire herd. It remains to be seen whether similar disease outbreaks will have to be anticipated in northern Europe in the future.

Occurrence of concurrent trypanosomosis, theileriosis, anaplasmosis and helminthosis in Friesian, Zebu and Sahiwal cattle in Uganda.

An epidemiological investigation was conducted on farms in Tororo and Soroti districts of Uganda from January to February 2000 to determine the cause of reported persistent mortality of cattle. Blood and faecal material of 98 cattle comprising of 33 Friesians, 58 Zebu and 7 Sahiwal were examined. Results revealed that seven (7.1 %) cattle had trypanosome infection, mainly due to Trypanosoma vivax and T. brucei, 17 (17.3%) Fasciola infection, 28 (28.6%) gastrointestinal nematode infection, 33 (33.7%) Theileria sp. infection and 13 (13.3%) Anaplasma marginale infection. Mixed infections were detected in 30%, 20.6% and 43 % of the Friesian, Zebu and Sahiwal cattle respectively. Anaemia (PCV < 25) was detected in 24%, 19% and 14% of the Friesian, Zebu and Sahiwal cattle respectively. Persistent mortality of cattle on these farms could have been due to either single or mixed parasitic infections probably exacerbated by malnutrition.