Heartwater: A situation report of the Southern district of Botswana from 2017 to 2019.

Heartwater is a tick-borne haemoparasitic disease that can limit agro-business expansion in Botswana. It poses a threat to national food security due to low animal production as well as livestock morbidity and mortality. This report gives a snapshot view of heartwater in the Southern district of Botswana. Ixodid ticks parasitizing livestock in four Southern sub-districts of Botswana were collected and identified using morphological and molecular methods. A wide distribution of Amblyomma hebraeum in all four Southern sub-districts was revealed. The annual number of heartwater cases across the Southern district of Botswana was determined from veterinary clinical case reports and confirmed through Giemsa-stained brain smears. A concerning gradual annual increase in heartwater cases was shown in the Moshupa sub-district - a hardveld terrain with rock outcrops where the vector thrives. Goats were affected most (55%) by heartwater followed by sheep (37%) and then cattle (8%). Farmers were interviewed on the management of the heartwater burden within their respective sub-districts and they reported that their animals were affected by heartwater despite 17 out of the 27 farmers interviewed attempting to control vectors through acaricide use. The presented heartwater situation warrants further investigation of the prevalence of heartwater and the effectiveness of existing disease control interventions in the disease-endemic Southern district of Botswana.

Morphological identification of ticks (Acari: Ixodidae) infesting donkeys (Equus asinus) in Maputo Province, Mozambique.

Donkeys (Equus asinus) are rustic animals, but in Africa's poorest regions, they can present multiple health problems, including tick infestation. The study's objective was to determine the species composition of ticks that infest donkeys in Maputo Province (Mozambique). Ticks were collected in five conveniently selected southern districts of Maputo Province (Moamba, Matutuíne, Marracuene, Boane, and Matola) and were identified to species level using a stereoscopic microscope with the aid of dichotomous identification keys. In total, 500 ticks were collected from all 88 selected donkeys. Three genera of ticks were identified, namely Rhipicephalus (97.2%; 486/500), Amblyomma (2.2%; 11/500), and Hyalomma (0.6%; 3/500). Seven species were identified, of which Rhipicephalus evertsi evertsi with 50.4% (252/500) was the most prevalent, followed by Rhipicephalus appendiculatus (27.4%; 137/500), Rhipicephalus turanicus (11.6; 10/500), Rhipicephalus (boophilus) microplus (6.8; 20/500), Amblyomma hebraeum (2.2%; 11/500), Rhipicephalus sanguineus (1%; 5/500) and Hyalomma truncatum (0.6%; 3/500). Rhipicephalus evertsi evertsi occurred in all locations, whereas Hyalomma truncatum occurred only in the Boane district. Males were the most prevalent (67.2%; 336/500). The study revealed that donkeys in Maputo Province were infested with seven tick species of which R. evertsi evertsi was the main species.

Acaricide resistance in Rhipicephalus appendiculatus ticks collected from different farming systems in Zimbabwe.

The larval packet test (LPT) was used to investigate resistance in Rhipicephalus appendiculatus ticks to the amidine (amitraz) and organophosphate (chlorfenvinphos) chemical acaricides in different farming systems in Mashonaland West Province in Zimbabwe. The study results showed emerging resistance (ER) to amitraz in small-scale and commercial farming systems. The tick populations in communal farming systems were susceptible to both acaricides. A similar trend was observed for chlorfenvinphos, where ER was observed in the small-scale farming systems compared to communal and commercial farms. Furthermore, resistance ratios (RR) were higher for amitraz as compared to chlorfenvinphos. This study suggests that management practices, acaricide formulations, applications on cattle, intensity, and frequency of use could be pre-disposing factors for the emerging resistance towards amitraz observed in R. appendiculatus ticks found in small-scale and commercial farming systems. Amitraz is the most common and frequently used acaricides in all farming systems, and hence, resistance is developing much faster than organophosphates. There is a need to investigate further acaricide use and management practices in Zimbabwe's cattle farming systems to develop practical strategies for prevention and management of tick acaricide resistance.

Ixodid ticks of African buffalo (Syncerus caffer), impala (Aepyceros melampus) and elephant (Loxodonta africana) in five protected park estates in the Zambezi valley, Zimbabwe.

Wildlife hosts many pathogens of economic importance and is considered as a reservoir of important tick-borne diseases of livestock in southern Africa. The species composition of ticks parasitizing buffalo (Syncerus caffer), impala (Aepyceros melampus) and elephant (Loxodonta africana) was investigated in five protected parks in the Zambezi valley, Zimbabwe. A total of 1104 adult ticks was collected from 75 adult animals comprising five buffaloes, five elephants and five impalas drawn from five protected wildlife parks. Five tick species belonging to two genera were recovered, with Rhipicephalus decoloratus being the most prevalent species in all the three animal groups. Amblyomma hebraeum was only recovered from buffaloes whereas Rhipicephalus zambeziensis was recovered from buffalos and elephants. Significant differences in mean tick species distribution and concentration were observed amongst the wildlife parks and these appeared to be influenced by the number of hosts in each park. The study revealed that buffaloes are the major host of R. decoloratus in the Zambezi valley. The presence of these ixodid ticks within the Zambezi valley may have significant ecological and economic impacts on wildlife conservation, domestic animals and human health.

Population structure and genetic diversity of Rhipicephalus microplus in Zimbabwe.

Recently there was an expansion in the geographic range of Rhipicephalus microplus in Zimbabwe. In order to understand gene flow patterns and population structure in this highly invasive and adaptable cattle tick, a population genetics study was carried out. Eighty-seven R. microplus tick samples drawn from 5 distinct populations were genotyped using eight polymorphic microsatellite loci. Genetic diversity (He) was high (0.755-0.802) in all the populations, suggesting high levels of gene flow with 97% of genetic variation found within populations and 3% amongst populations. No isolation by distance was observed with low but significant genetic differentiation amongst the populations (0-0.076). Most of the sampled individuals had admixed genetic backgrounds, except for those from Matabeleland North whose genetic makeup appeared different from the rest. Rhipicephalus microplus was recently recorded in this area and the environmental conditions do not support survival of the tick there. These results confirm recent range expansion of the tick and the lowest genetic diversity recorded in the Matabeleland North population is suggestive of a founder effect, which may lead to genetic drift. Generally, the very low levels of genetic differentiation amongst the populations could be a result of the frequent movement of livestock from one area to another, which will have implications for disease control. This study offers further opportunities to study evolutionary adaptation of R. microplus in Zimbabwe and southern Africa.

Genotyping acaricide resistance profiles of Rhipicephalus microplus tick populations from communal land areas of Zimbabwe.

Acaricide resistance is one of the greatest threats towards the successful control of vector ticks worldwide. Communal farmers of Zimbabwe use amitraz as the most common acaricide with occasional usage of pyrethroids and organophosphates. As a strategy towards developing an effective acaricide resistance management system in Zimbabwe, screening was done by genotyping Rhipicephalus microplus tick populations using molecular markers associated with resistance to these chemicals. The frequency of the mutant allele for the octopamine/tyramine receptor marker associated with amitraz resistance was high (0.55) and a large proportion 78.5% (288/367) of heterozygote genotypes were observed indicating balancing selection. Of the communal dipping tanks where R. microplus occurred 37.8% (39/103) showed complete resistance genotypes for amitraz. The carboxylesterase marker that has been associated with resistance to organophosphate and pyrethroids indicated no selection pressure in these chemical groups with a low frequency (0.052) of the mutant allele and 89.6% (329/367) sampled ticks showing homozygous susceptibility genotypes. Heterozygous genotypes were present at 27.2% (28/103) of the dipping tanks. The L641 mutation in the voltage-gated sodium channel gene associated with pyrethroid resistance was not detected in Zimbabwean samples. This would suggest a different mechanism of resistance to pyrethroids in these tick populations. Sequence analysis of the octopamine/tyramine receptor gene revealed the presence of other mutations in this region, it will be important to investigate their association with amitraz resistance. These results present the first molecular genotyping of resistance profiles of R. microplus tick populations from Zimbabwe.

Communal farmers' perceptions of tick-borne diseases affecting cattle and investigation of tick control methods practiced in Zimbabwe.

Tick borne diseases (TBDs) are responsible for huge economic losses in cattle production in most African countries where the majority of cattle owners are the resource poor communal farmers. Governments have initiated and co-ordinate tick control programs with farmers required to contribute funds for their sustenance. The success of these programs will hinge upon the involvement of communal farmers in their design, implementation and evaluation. To this end, 313 communal farmers (approximately 8.4% response rate) were interviewed and 3 focus group discussions were carried out in the southern low-veld part of Zimbabwe with the objectives of investigating communal farmers' perceptions on TBDs affecting cattle, level of participation in government initiated tick control programs, other tick control methods practiced, types of acaricides used and their perceived effectiveness. There was a general awareness of TBDs with 67.7% (n=212) farmers being able to describe tick diseases with names or clinical and post-mortem signs. The diseases or problems frequently associated with ticks were cowdriosis (38%, n=119), mastitis (36.7%, n=115), anaplasmosis (36.1%, n=113), body damage (28.4%, n=89), babesiosis (24.6%, n=77) and poor body condition (16.6%, n=52). Cattle mortalities due to TBDs were reported by 23.8% (n=74) of the farmers. The plunge dip was consistently used by farmers (70.3%, n=220) to control ticks. Other tick control methods practiced were the hand spraying (67.4%, n=211), hand dressing (16.6%, n=52), traditional methods (5.4%, n=17), use of pour-ons (4.5%, n=14) and smearing (2.2%, n=7). The formamidines were the most common class of acaricide used (59.4%, n=186), followed by synthetic pyrethroids (29.1%, n=91), macro cyclic lactones (12.8%, n=40) and organophosphates (4.5%, n=14). Most farmers (75.2%, n=231) perceived these acaricides to be effective in controlling ticks. The results of focus group discussions showed that a number of factors influenced the success of government initiated tick control programs and these included inconsistent supply of acaricides, unaffordable dipping fees, lack of water, long distance to the dip tank, lack of information on dipping procedures and lack of knowledge on strategies for delaying acaricide resistance. This study demonstrates that while farmers can be a valuable source of information with regards to the epidemiology of tick borne diseases affecting their cattle, there is still need for further training in understanding the TBDs and strategies for their control.

Growth performance of Brangus steers fed graded levels of sun-dried broiler litter as a substitute for cottonseed cake.

An experiment was conducted to determine the optimum inclusion levels of dried broiler litter (DBL) as a substitute for cottonseed cake (CSC) in fattening diets for Brangus steers. Thirty Brangus steers were randomly allocated to five groups of six animals each. Each group was fed one of the experimental diets which had CSC substituted for DBL at levels of 0 (DBL0), 50 (DBL50), 100 (DBL100), 150 (DBL150) and 200 g/kg (DBL200). Average daily gain (ADG), dry matter intake and live weight gain (LWG) were measured over a period of 90 days, and the results were analysed using the MIXED procedures of SAS. Linear and quadratic effects of DBL inclusion on dry matter intake, LWG and ADG were also determined. Results showed interactions between diet and time that significantly affected ADG and LWG (p < 0.05). Both ADG and LWG decreased with increases in DBL inclusion with the depressed performance becoming more pronounced with time. Linear and non-linear decreases in LWG and ADG, respectively, were observed with increasing levels of DBL. The DBL50 diet resulted in performance that was similar to DBL50 and was 4% cheaper. Broiler litter can be used as a supplement for conventional protein sources, but at higher inclusion levels, it needs to be augmented by increased fermentable energy.

An update on the ecological distribution of the Ixodidae ticks in Zimbabwe.

In total 7657 ticks were collected from 121 dip tanks in 12 districts representative of Zimbabwe's five ecological regions between September 2013 and May 2014. Based on morphological traits four genera and 13 species of ticks were identified. Amblyomma hebraeum (60.3 %), Rhipicephalus microplus (58.7 %), Rhipicephalus decoloratus (47.1 %), Rhipicephalus appendiculatus (56.2 %), Rhipicephalus evertsi evertsi (67.8 %), Rhipicephalus (near) punctatus (13.2 %), Hyalomma truncatum (38 %) and Hyalomma rufipes (46.3 %) were found in all the ecological regions of the country. Amblyomma variegatum and Rhipicephalus compositus (0.8 %) were only found in the north central part of the country while Rhipicephalus simus (5 %) had a sparse distribution. The Haemaphysalis leachi group (1.7 %) and Rhipicephalus sanguineus (1.7 %) were found whenever dogs were sampled suggesting these could be widespread throughout the country. The study confirmed the continued limited distribution of A. variegatum (3.3 %) in the north central parts of the country, whereas A. hebraeum was found to have a wide distribution also encroaching areas of high rainfall and lower temperatures where it was not previously recorded. A parapatric relationship existed between these two Amblyomma species. Rhipicephalus appendiculatus was also widely distributed although its presence was dominant in the cooler and wetter parts of the country. The traditionally held view that Hyalomma species and R. evertsi evertsi can survive well under diverse conditions is upheld in this study. Rhipicephalus microplus was also present in dry regions but its adaptability to these regions requires further investigation.

Validity of Weight Estimation Models in Pigs Reared under Different Management Conditions.

A study was carried out to determine the relationship between linear body measurements and live weight in Landrace and Large White pigs reared under different management conditions in Zimbabwe. Data was collected for body length, heart girth, and live weight in 358 pigs reared under intensive commercial conditions. The stepwise multiple linear regression method was done to develop a model using a random selection of 202 records of pigs. The model showed that age, body length, and heart girth were useful predictors of live weight in these pigs with significantly high positive correlations observed. The model was internally validated using records of the remaining 156 pigs and there was a significantly high positive correlation between the actual and predicted weights. The model was then externally validated using 40 market age pigs reared under communal conditions and there was a significantly low positive correlation between the actual and predicted weights. The results of the study show that while linear measurements can be useful in predicting pig weights the appropriateness of the model is also influenced by the management of the pigs. Models can only be applicable to pigs reared under similar conditions of management.

Sow removal in a commercial pig herd in Zimbabwe.

A study was carried out at a 2,200 sow farrow-finisher facility in Zimbabwe to determine the main reasons for sow removal and the season when removal was most common. Data on the number of sows culled and the reasons for culling as well as mortalities was recorded weekly for a 12-month period. The culling frequency was 52.8 % (n = 1 162). Descriptive statistics indicated that reproductive problems accounted for 70.8 % (n = 823) of sow removals, death (15.6 %, n = 181), lameness (4.6 %, n = 53), miscellaneous (2.5 %, n = 29), production (2.2 %, n = 26), peripartum (2.2 %, n = 25) and age (2.2 %, n = 25). The results also showed that culling was highest in gilts and primiparous sows (41.3 %, n = 480) with the least culling being observed in sows in parity 7 (5.3 %, n = 61). The hot wet season was observed to be the one when culling was most common (33.5 %, n = 389) with the least being in the cold dry season (17 %, n = 198). It was concluded that most of the sow removal was unplanned. There is a need to improve replacement gilt selection, reproductive efficiency, health and nutrition management to increase productivity in a sow unit.

The prevalence of Taenia saginata cysticercosis in the Matabeleland Provinces of Zimbabwe.

Records were collected for Taenia saginata cysticercosis infections in cattle slaughtered at the Cold Storage Company Abattoir in Bulawayo, Zimbabwe, between January 2006 and December 2007. The cattle were drawn from the two Matabeleland provinces in the dry western and southern parts of the country. A total of 86,080 cattle were slaughtered during the period. The average prevalence of T. saginata cysticercosis was found to be 1.6% (n = 1 364) with Matabeleland North having a higher prevalence of 2.8% (n = 629) and Matabeleland South 1.2% (n = 735). There were no significant seasonal differences (p > 0.05) in incidences of T. saginata cysticercosis during the study although numerically, the prevalence of T. saginata cysticercosis was higher in the wet season. There was no significant difference (p > 0.05) in the prevalence of T. saginata cysticercosis in different age classes of cattle slaughtered. Of the infected carcasses, a great proportion of these had live cysts (1.4%) while few had dead cysts (0.2%). Most of the cattle condemned were below the age of 2 years and some were full adults (p < 0.05). There was a significant association between farm type (p < 0.05) and prevalence of T. saginata cysticercosis with most infections being observed in the communal farming system. Though the prevalence of T. saginata cysticercosis appears to be low, there is a need to conscientize the farmers to avoid losses due to carcasses condemnation at slaughter houses which will have a negative financial impact to the individual farmer. There is also a need to investigate such cases even further to reduce zoonotic consequences due to the undetected cases in communal areas.