Distribution and molecular identification of ixodid ticks infesting cattle in Kilombero and Iringa Districts, Tanzania.

BACKGROUND: Hard ticks infesting cattle are vectors of Tick-borne diseases that causes major public health problems and considerable socioeconomic losses to the livestock industry in tropical and subtropical countries. A repeated cross-sectional study was carried out by collecting ticks on cattle during the wet and dry seasons from January to August 2021 in order to determine hard tick prevalence, distribution, and abundance on cattle in Kilombero and Iringa Districts of Tanzania. The collected ticks were identified morphologically using published morphological keys under a stereomicroscope and confirmed by polymerase chain reaction (PCR) and sequencing. RESULTS: Out of 740 examined cattle, 304, (41.08%) were infested with ticks. In total, 1,780 ticks were counted on one side of the animal's body and doubled, whereby resulting in a total of 3,560 ticks were recorded. Individual tick burden ranged from n = 2 to 82 ticks per animal, with a mean tick burden of n = 11.7 ± 0.68 per animal. A total of 1,889 ticks were collected from infected cattle including 109 additional ticks observed while collecting ticks based on the animal's posture when restrained to the ground. Out of 1,889 ticks, nine species from three genera were identified morphologically: 1,377 fit in the genus Rhipicephalus, 459 to the genus of Amblyomma, and 53 to the genus Hyalomma. Rhipicephalus microplus was the most prevalent (n = 909, 48.1%), followed by Rhipicephalus evertsi (n = 310, 16.4%), Amblyomma lepidum (n = 310, 16.4%), Rhipicephalus appendiculatus (n = 140, 7.4%), Amblyomma gemma (n = 120, 6.4%), Hyalomma rufipes (n = 50, 2.6%), Amblyomma variegatum (n = 29, 1.5%), Rhipicephalus decoloratus (n = 18, 1.0%), while the least common was Hyalomma albiparmatum (n = 3, 0.2%). Tick diversity was higher in Iringa compared to Kilombero District. Tick prevalence was higher in wet season (n = 148, 41.11%). Ticks were widely distributed in different parts of the host body, with the highest distribution on zone 4 (n = 1,060, 56.11%), which includes groin, flank, abdomen, and around inner thigh of the hind legs and the lowest distribution on zone 2 (n = 14, 0.74%), which includes the back surface of the body. Both Amblyomma lepidum and Rhipicephalus microplus species were found in all the five body zones, and with the highest proportions recorded on zone 4: A. lepidum (n = 209, 67.42%) and R. microplus (n = 714, 78.55%). The nine tick species identified morphologically were also confirmed using molecular methods. However, during sequencing, two species (Rhipicephalus appendiculatus and R. decoloratus) had poor quality sequences and were excluded from the sequence analysis. Sequencing results indicated high nucleotide identity (96-100%) with sequences available in GenBank and Barcode of Life Database (BOLD). The phylogenetic analysis of partial mitochondrial COI and 16S rRNA gene sequences of ticks were used to confirm the morphological identification. CONCLUSION: The results showed a high burden of tick infestation on cattle, which could reduce animal production and potentially increase the risk of tick-borne diseases. Therefore, it is necessary to explore the epidemiological and molecular aspects of various tick species in other regions of Tanzania.

Tick populations and molecular detection of selected tick-borne pathogens in questing ticks from northern and central Tanzania.

Ticks are vectors and reservoirs of a variety of pathogens including protozoa, bacteria and viruses which cause tick-borne diseases (TBDs) in humans and livestock. TBDs pose serious constraints to the improvement of livestock production in tropical and subtropical regions of the world. Despite their wide distribution, information on the tick and pathogen relationship is scarce in Tanzania. We used nested PCR and sequencing to screen pathogens of public and veterinary health importance in ticks collected by flagging from four districts of Tanzania. In total, 2021 ticks comprising nine species were identified. DNA from ticks was pooled according to tick species, developmental stage, and location, then screened for Babesia bigemina, Babesia bovis, Theileria parva and Coxiella burnetii. Out of 377 pools, 34.7% were positive for at least one pathogen. Theileria parva was the most abundant with a minimum infection rate (MIR) of 2.8%, followed by B. bigemina (MIR = 1.8%) and B. bovis (MIR = 0.8%). Multiple pathogens detection was observed in 7.2% of the tested pools. However, PCR screening of individual tick DNA revealed that only 0.3% of the examined pools had co-infection. DNA of C. burnetii was never detected in any tick DNA pool. The MIR of tick-borne pathogens (TBPs) differed significantly among districts, seasons, tick species, and tick developmental stages. Sequence analysis showed that B. bigemina RAP-1a, B. bovis SBP-4, and T. parva p104 genes were conserved among pathogens in the four districts. Despite the absence of C. burnetii in ticks, considering its pathogenic potential, it is essential to continue monitoring for its possible recurrence in ticks. This information adds to the knowledge of TBPs epidemiology and will contribute to the scientific basis for planning future control strategies.

Epidemiology of tick-borne pathogens of cattle and tick control practices among mixed farming and pastoral communities in Gairo and Monduli districts, Tanzania.

Tick-borne diseases including East Coast fever, anaplasmosis and babesiosis constitute a major constraint to improving livestock production worldwide, including Tanzania. Determination of the prevalence and factors associated with the occurrence of pathogens in cattle is important for informed decision making on the control and prevention of these diseases. However, little is known about the epidemiology of these pathogens in cattle in some regions of Tanzania. Therefore, this study aimed at establishing the prevalence of Anaplasma marginale, Babesia bigemina, Babesia bovis and Theileria parva in cattle, determine the risk factors associated with infection with these pathogens and also to assess tick control practices in Gairo and Monduli districts of Tanzania. Out of the 520 cattle sampled, the majority (82.9%) were infested with ticks of different species, predominated by Rhipicephalus decoloratus (42.7%), Amblyomma variegatum (31.3%), Rhipicephalus pulchellus (23.1%) and Rhipicephalus appendiculatus (17.7%). Other ticks that were found on cattle included Rhipicephalus microplus (15.8%), Amblyomma gema (13.8%), Rhipicephalus evertsi (12.9%), Amblyomma lepidum (8.1%), Hyalomma truncatum (2.9%) and Hyalomma albiparmatum (2.1%). On microscopy 23 (4.4%) of 520 cattle were positive for hemoparasites. Of the 23 positive cattle, 13 (2.5%), 6 (1.2%) and 3 (0.6%) were monolithically infected with A. marginale, T. parva, and B. bovis respectively, while one (0.2% %) had co-infections of T. parva and A. marginale. The number of positive cattle increased to 184 (35.4%), when they were subjected to detection with PCR. This included the 23 samples that were positive on microscopy. Based on PCR, the overall prevalence of the pathogens from the two districts was 11.5%, 11.2%, 6.2% and 2.5% for B. bigemina, A. marginale, T. parva and B. bovis, respectively. Hemoparasite co-infection occurred in 6.9% of the cattle examined. The prevalence of co-infections was 2.7%, 4%, and 0.02% for T. parva/A. marginale, B. bigemina/A. marginale and B. bigemina/A. marginale/T. parva, respectively. Cattle with co-infections had significantly lower (p < 0.005) mean packed cell volume as compared to cattle with mono-infections. The majority (96%) of cattle examined were subjected to different methods of tick control. A number of risk factors were shown to be associated with the occurrence of tick-borne pathogens in cattle. Higher prevalence of A. marginale may be due to its wide range of biological and mechanical transmission. These findings could be used to strengthen future control programs for ticks and tick-borne diseases in the study areas.

Determination of the prevalence of trypanosome species in cattle from Monduli district, northern Tanzania, by loop mediated isothermal amplification.

Bovine African trypanosomosis (BAT) remains one of the major vector-borne diseases with serious impediment to cattle production and economic advancement in sub-Saharan Africa. The present study evaluated the performance of the trypanosome-species-specific loop-mediated isothermal amplification (LAMP), using parasite DNA obtained from 295 indigenous Tanzanian short horn Zebu (TSHZ) and Boran crosses in Monduli district within northern Tanzania, against routine microscopy on Giemsa-stained blood films. Compared to parasitological data in which the prevalence of BAT was estimated at 2.4% (95% CI 0.7-4.1%), LAMP increased the prevalence to 27.8% (95% CI 22.3-32.5%), of which 11.9% (95% CI 8.2-15.6%) were monolytic infections with Trypanosoma vivax, while 13.6% (95% CI 9.7-17.5%) were coinfections of either T. vivax and Trypanosoma brucei subspecies or T. vivax and Trypanosoma congolense, respectively. Among the T. brucei subspecies detected, 0.7% (95% CI 0-1.7%) were human-infective Trypanosoma brucei rhodesiense. Our study is in concordance with previous reports and suggests that LAMP is a potential tool for routine diagnosis of trypanosomes in domestic animals in BAT endemic regions. According to LAMP, T. vivax seems to be the predominant trypanosome species circulating among the indigenous Monduli cattle. Importantly, the detection of T. b. rhodesiense in cattle in such wildlife-domestic-animal-human-interface areas poses a risk of contracting human African trypanosomiasis (HAT) by local communities and tourists. Continuous trypanosome surveillances in domestic animals, humans, and tsetse flies using sensitive and specific tests such as LAMP are recommended.

Occurrence of haemoparasites in cattle in Monduli district, northern Tanzania.

Haemoparasite infections are among the most economically important cattle diseases in sub-Saharan Africa. The present study investigated the occurrence of haemoparasites in 295 indigenous cattle from five villages (Mswakini, Lake Manyara, Naitolia, Makuyuni and Nanja) of the Monduli district, a wildlife-domestic animal-human interface area in northern Tanzania. The data showed that the overall occurrence of haemoparasites in the sampled cattle was 12.5% (95% CI: 8.7% - 16.3%), involving single and mixed infections with Theileria parva, Anaplasma marginale, Babesia bovis, Trypanosoma vivax and Trypanosoma brucei. The highest haemoparasite occurrence was recorded in Lake Manyara (18.3%; 95% CI: 8.5% - 28.1%), and the lowest was recorded in Nanja (6.5%; 95% CI: 0.4% - 12.6%). This preliminary study, furthermore, provided evidence of the possible arthropod vectors (ticks and tsetse flies) that may be involved in the transmission of haemoparasites to cattle in the Monduli district. It is envisaged that this survey will stimulate more studies to determine the prevalence of haemoparasites in livestock by using more sensitive molecular techniques.