Preliminary survey of ticks (Acari: Ixodidae) on cattle in northern Sudan

In a cross sectional survey conducted during the period June 2001 to July 2002, the geographical distribution of ticks on cattle in the Sudan was determined. Seventeen locations were surveyed from Northern, Central, Eastern, Western, Blue Nile and White Nile Provinces. Total body collections of ticks were made from 20 cattle at each location. Four tick genera and 11 species were identified. The tick species collected included Amblyomma lepidum, Amblyomma variegatum, Boophilus decoloratus, Hyalomma anatolicum anatolicum, Hyalomma dromedarii, Hyalomma impeltatum, Hyalomma marginatum rufipes, Hyalomma truncatum, Rhipicephalus evertsi evertsi, Rhipicephalus sanguineus group and Rhipicephalus simus simus. Major ecological changes have occurred due to extensive animal movement, deforestation, desertification and establishment of large mechanized agricultural schemes. These factors have certainly affected the distribution of ticks and tick-borne diseases in the Sudan. The absence of A. variegatum and A. lepidum in northern Sudan was not surprising, since these tick species are known to survive in humid areas and not in the desert and semi-desert areas of northern Sudan. The absence of B. annulatus in northern and central Sudan is in accordance with the finding that this tick species is restricted to the southern parts of the central Sudan. The presence of H. anatolicum anatolicum in Um Benin in relatively high abundance is an interesting finding. The present finding may indicate that the southern limit of this species has changed and moved southwards to latitude 13 degrees N. It is concluded that major changes in tick distribution have taken place in the Sudan.     

Development of Hyalomma lusitanicum under laboratory conditions

At the constant temperature of 25 degrees C and relative humidity (RH) of 84%, the average pre-oviposition period of Hyalomma lusitanicum was 47 days, the oviposition lasted an average of 26 days and the total egg production was an average of 6320 per female. At 16 degrees C the females did not lay eggs at all, but those which survived for 1 year and were transferred thereafter to 25 degrees C and 84% RH laid viable eggs. At 35 degrees C, the oviposition was identical at all levels of RH tested (25, 62 and 93%). At 25 degrees C, the pre-oviposition period was shorter at 93% RH, and the number of eggs laid was fewer at 25% RH. The eggs hatched in 32-40 days, the hatching percentage being lower in batches of eggs laid at the beginning and at the end of the oviposition period. The larval and nymphal moultings were not influenced by the type of host. As the temperature increased, the pre-moult period became shorter. The engorged larvae were more sensitive to the low RH than the engorged nymphs, whose moulting percentage was always greater than 72 in all regimes. Low temperature and high humidity had a favourable effect on the survival of unfed nymphs. The female-to-male ratio was 1:2. Hyalomma lusitanicum always behaved as a 3-host tick. The adults did not engorge on rabbits. The female ticks engorged on calves weighed an average 543 mg. Ticks maintained at 25 degrees C and 84% RH and engorged on calves completed the life cycle in 138-196 days, which does not include the period of chitinization of about 30 days. More than half of this period was spent in egg laying and hatching.     

Parasites of domestic and wild animals in South Africa. XXIX. Ixodid ticks on hares in the Cape Province and on hares and red rock rabbits in the Orange Free State.

One hundred and seventeen scrub hares, Lepus saxatilis, were examined for ixodid ticks in various regions of the Cape Province. They were infested with 18 tick species and the seasonal abundances of the immature stages of Amblyomma hebraeum, Amblyomma marmoreum, Hyalomma marginatum rufipes, Rhipicephalus appendiculatus and Rhipicephalus glabroscutatum and all stages of Rhipicephalus oculatus and the adults of a Rhipicephalus sp. (near R. oculatus) were determined. Seventy-two scrub hares on 3 farms in the Orange Free State harboured 10 ixodid tick species and the seasonal abundances of the immature stages of H. marginatum rufipes and Hyalomma truncatum and all stages of Rhipicephalus punctatus were determined. Thirty Cape hares, Lepus capensis, examined in the northern Cape Province harboured 5 tick species and the seasonal abundances of the immature stages of H. marginatum rufipes and H. truncatum were determined. Thirty-four Cape hares examined in the south-western Orange Free State carried 6 tick species and the seasonal abundance of immature H. marginatum rufipes was determined on these animals. Twenty-eight Smith's red rock rabbits examined on 2 farms in the south-western Orange Free State were infested with 7 tick species.     

Parasites of domestic and wild animals in South Africa. XIII. The seasonal incidence of adult ticks (Acarina: Ixodidae) on cattle in the Northern Transvaal.

Ticks were collected over a period of 13 months, at approximately fortnightly intervals, from 6 Africaner oxen kept on the farm Nylsvley in the Naboomspruit District. The 8 species of Ixodidae collected were, in order of abundance, Rhipicephalus appendiculatus, R. evertsi evertsi, Hyalomma marginatum rufipes, H. truncatum, Amblyomma hebraeum, R. simus, Boophilus decoloratus and Ixodes cavipalpus. The relative abundance of adult ticks of these species, their predilection feeding sites and seasonal fluctuations in numbers are discussed.     

The transovarial transmission of Babesia caballi by Hyalomma truncatum

Babesia caballi, isolated from a horse that originated from South West Africa/Namibia, was transmitted transovarially by adult Hyalomma truncatum. B. caballi proved to be highly infective for adult H. truncatum. Forty-five per cent of ticks feeding on a reacting animal with an extremely low parasitaemia became infected. In spite of a low parasitaemia, the ticks were severely affected by the parasite. Seventy per cent of the infected ticks either died during oviposition or after laying only a few eggs. The features of the infection in horses were: a prepatent period of 10 days, very low parasitaemias with low pathogenicity and spontaneous recovery of the infected animals.     

Parasites of domestic and wild animals in South Africa. XXXI. Adult ixodid ticks on sheep in the Cape Province and in the Orange Free State.

Four to 10 Dorper sheep on each of 12 farms in the Cape Province and 3 farms in the Orange Free State were examined for adult ixodid ticks at approximately 2- to 4-weekly intervals over periods varying from 4 to 18 months, commencing during January, February or April 1989. The farms in the Cape Province were located in the north-west, south-west and south of the province. Those in the Orange Free State were situated in the north-east and in the south. The sheep in the Cape Province harboured 10 species of ixodid ticks and the seasonal abundances of Ixodes rubicundus, Rhipicephalus evertsi evertsi, Rhipicephalus gertrudae and Hyalomma truncatum were determined. The animals in the Orange Free State were infested with 7 tick species and the seasonal abundances of I. rubicundus, R. evertsi and Hyalomma marginatum rufipes were determined.     

Arthropod parasites of springbok, gemsbok, kudus, giraffes and Burchell's and Hartmann's zebras in the Etosha and Hardap Nature Reserves, Namibia.

A total of 48 springbok, 48 gemsbok, 23 kudus and 6 giraffes were examined for ticks and lice, while 9 Burchell's zebras and 6 Hartmann's mountain zebras were examined only for ticks. Springbok and gemsbok were shot in both the Etosha National Park in the north and the Hardap Nature Reserve in the south of Namibia. All the other animals were shot in the Etosha National Park. A total of 7 ixodid tick species and 8 lice species were recovered. The springbok carried few ticks. The adults of a Rhipicephalus sp. (near R. oculatus) were most numerous on the gemsbok, especially during November. The kudus were the only animals harbouring Rhipicephalus zambeziensis. Adult Hyalomma truncatum, followed by adult Hyalomma marginatum rufipes, were most abundant on the giraffes and adult Rhipicephalus evertsi mimeticus were commonest on the zebras.     

Tick diversity, abundance and seasonal dynamics in a resource-poor urban environment in the Free State Province

The objectives of this study were to determine the diversity, seasonal dynamics and abundance of ticks infesting cattle in urban, small-scale farming communities in and around Botshabelo and Thaba Nchu in the eastern Free State Province, South Africa. A total of ten cattle, ear-tagged for individual identification, were investigated monthly at each of five localities. Adult ticks were removed from the right hand side of each animal and placed in containers filled with 70% ethanol. They were subsequently identified and their numbers quantified. Immature Otobius megnini were counted but not removed. A total of 244,538 adult ticks of ten different species were collected over the 12-month study period. The tick species, in decreasing order of relative abundance, were: Boophilus decoloratus (87.26%), Rhipicephalus evertsi evertsi (6.86%), Hyalomma marginatum rufipes (2.42%), Otobius megnini (1.85%) Rhipicephalus follis (0.76%), Rhipicephalus gertrudae (0.54%), Rhipicephalus sp. (0.21%), Ixodes rubicundus (0.08%), Hyalomma truncatum (0.01%) and Margaropus winthemi (0.004%). The three most abundant species, namely B. decoloratus, R. evertsi evertsi and H. marginatum rufipes, occurred at all localities but with significant differences in abundance. M. winthemi ticks occurred only in the Thaba Nchu area and were not found at any of the there localities in Botshabelo. Significant differences in tick burdens between the six warm months (September to February) and the six cooler months (March to August) were found for most of the species recorded. Boophilus decoloratus occurred in significantly higher numbers in autumn (March to May) and winter (June to August) compared to spring (September to November) and summer (December to February), with 76.8% of the total B. decoloratus burden occurring during the cooler months.     

Reliminary survey of ticks (Acari: Ixodidae) on cattle in Central Equatoria State, Southern Sudan

In a preliminary survey conducted in 2005, the species composition and seasonality of ticks infesting cattle in Central Equatoria State, Southern Sudan was determined. Three locations were selected (Gumbo, Khor Rumla and Nyaing) and surveyed every 3 months. Two cattle herds in each of the three locations were visited four times during the study period. Total body collections of ticks were made from each of five cattle (Nilotic Zebu breed) kept in six different herds. Four tick genera and ten species were identified. The tick species identified were Amblyomma lepidum, Amblyomma variegatum, Boophilus annulatus, Boophilus decoloratus, Hyalomma marginatum rufipes, Hyalomma truncatum, Rhipicephalus appendiculatus, Rhipicephalus evertsi evertsi, Rhipicephalus praetextatus and Rhipicephalus sanguineus group. The highest number of ticks was collected in October during the rainy season. A finding of great significance was that R. appendiculatus, vector of East Coast fever, has now firmly established itself throughout the year with possible implications for cattle production in Central Equatoria State.     

Effect of infection by Babesia spp. on the development and survival of free-living stages of Boophilus annulatus

Oviposition, egg hatching and survival of newly-hatched larvae of Boophilus annulatus were studied in relation to infection by Babesia species and different temperature regimens. Infection of female ticks by Babesia bigemina or B. bovis had no effect on the time elapsed between engorgement and oviposition. The duration of oviposition was shorter in infected females incubated at 25 degrees C or 35 degrees C and infected females laid fewer eggs than the controls. No larvae hatched at 16 degrees C. B. bigemina-infected eggs hatched more quickly than uninfected eggs at 35 degrees C. The hatching percentage of B. bigemina-infected eggs was reduced by 50% at an incubation temperature of 25 degrees C and by 75% at 35 degrees C. At 16 degrees C there was no difference in the duration of survival of infected and non-infected larvae but at 25 degrees C and 35 degrees C the mean survival period of infected larvae was significantly lower than those of controls.     

Tick infestation of Borana cattle in the Borana Province of Ethiopia

A study was conducted to identify and determine burdens of ticks infesting Borana cattle in the Borana Province of Ethiopia. Rhipicephalus pulchellus, Rhipicephalus pravus, Rhipicephalus muhsamae, Rhipicephalus praetextatus, Rhipicephalus evertsi evertsi, Amblyomma gemma, Amblyomma variegatum, Amblyomma cohaerens, Amblyomma lepidum, Hyalomma truncatum, Hyalomma marginatum rufipes and Boophilus decoloratus were identified on the cattle. Their burdens ranged from 658-1,554 with a mean of 1,205 ticks per animal. Out of the total 6,025 ticks collected, about 82% were R. pulchellus, followed by R. pravus (about 8%) and A. gemma (5%). The other nine species of ticks accounted for only 5% of the total burdens. It is suggested that a strategic tick control method, aimed mainly at reducing the R. pulchellus burdens, with the objective of allowing a reasonable number of ticks to remain on cattle for the maintenance of endemic stability to tick-borne diseases be instituted.     

The effect of the ovine host parasitaemia on the development of Babesia ovis (Babes, 1892) in the tick Rhipicephalus bursa (Canestrini and Fanzago, 1877)

Batches of Rhipicephalus bursa adult ticks were fed on two lambs with 10.0% (batch 1) and 0.3% (batch 2) Babesia ovis parasitaemia, respectively. Haemolymph and eggs were checked for parasites daily after detachment, before and after appearance of B. ovis in the lamb's blood.B. ovis kinetes were found in the haemolymph and eggs earlier in the engorged ticks detached before appearance of the parasite in the host blood. Rates of haemolymph and egg infection with B. ovis as well as the percentage of infected eggs were much higher in batch 1 (10% lamb parasitaemia) than in batch 2 ticks (0.3% lamb parasitaemia). In eggs incubated at 28 degrees C the optimal period to look for kinetes seems to be days 4-9. Heavily infected ticks laid fewer less eggs within a shorter oviposition period. Pre-oviposition, pre-hatching periods and egg hatchability were not affected. Various parasitic forms are described in the haemolymph and the eggs.     

The sex ratio of Amblyomma cajennense (Acari: Ixodidae) with notes on the male feeding period in the laboratory

To evaluate the sex ratio of field collected nymphal Amblyomma cajennense ticks, we collected 5326 engorged nymphs from naturally infested horses in Pirassununga county and allowed them to molt to adults in the laboratory. They yielded a sex ratio of 1:1.83 (M:F). Three and two engorged females were collected from horses pastured at Pirassununga county and from tapirs pastured in Sorocaba county, respectively. These females were allowed to oviposit and their progeny were reared until the adult stage in the laboratory. Engorged females collected from Pirassununga yielded a sex ratio of 1:1.57 (M:F) and a sex ratio of 1.14:1 (M:F) were obtained for those ticks collected from tapirs. In addition, unfed tick larvae were collected from Pedreira county and reared in the laboratory until the adult stage. This collection yielded a sex ratio of 1.11:1 (M:F). These results showed significantly different (P<0.05) sex ratio constitutions among different tick populations. Laboratory rabbits were infested once with A. cajennense male ticks, which showed feeding periods varying from 7 to 86 days. During this period, the rabbits were re-infested regularly with A. cajennense female ticks. A total of 179 engorged females were collected from the rabbits and their engorged weight, feeding, preovioposition and egg incubation periods, weight of deposited eggs, percent of hatched eggs and egg production efficiency were compared to the male feeding period and to the number of live males present on the host. None of the female variables were affected by the male feeding period. Male ticks remained fertile for the whole feeding period. Percent of hatched eggs was the only female variable that significantly decreased as the number of live males decreased on the host. The results showed that although some A. cajennense populations are composed of more females than males after molting, this female predominance is compensated by a long male feeding period and maintenance of its reproductive performance.     

Studies on the development and survival periods of the non-parasitic stages of Boophilus microplus (Canestrini), in the climatic conditions of Ranchi (India).

Engorged female ticks of Boophilus microplus were exposed in wire-gauze cylinders and glass tubes in an experimental grass plot at monthly intervals during 1989, and egg laying, egg development and larval survival periods observed and recorded. Rainfall and atmospheric relative humidity had an important influence on tick activity. Egg production was maximum, hatching percentage was high, incubation and prehatch periods were short, and larval survival and total longevity periods were long for ticks exposed during the warm and humid rainy season from June to September. Dry atmospheric conditions severely affected egg development, egg hatch and larval survival. Eggs failed to hatch in the dry months from December to April and only 29-38% hatched after a long incubation period of 41 days in November and May. On grass, the larvae of ticks exposed in November survived for the shortest period of 28 days and the larvae of ticks exposed in June survived for the longest period of 133 days. Low winter temperatures reduced egg production and prolonged the pre-oviposition, oviposition and incubation periods. It is suggested that the results of this study might be helpful in the development of measures to control tick infestation by planned dipping and restricted grazing during the period from late June to January when the pasture has a substantial load of larval ticks.     

Infection rates of Theileria annulata in the salivary glands of the tick Hyalomma marginatum rufipes

Theileria annulata was experimentally transmitted to cattle on two occasions by the two-host tick Hyalomma marginatum rufipes. Transmission was transstadial; engorged nymphs fed on Theileria annulata-infected calves transmitted the disease as adults. Salivary glands of all partially fed and incubated adult ticks were heavily infected with Theileria parasites. Immatures attached rapidly and fed successfully on cattle. However, since the immature stages of this species normally feed on birds, this tick is unlikely to be an important vector in the field.     

Studies on ticks of veterinary importance in Nigeria XI. Observations on the biology of ticks detached from the red-flanked duiker (Cephamophys rufulatus) and parasites encountered in their blood

Some aspects of the biology of Amblyomma variegatum and Boophilus decoloratus detached from red-flanked duikers were studied. Smears were also made from the blood of the duikers and examined for the presence of parasites.Anaplasma marginale was the only blood parasite found in the blood smears. Compared with ticks detached from cattle, duiker ticks produced a greater number of eggs. The lengths and breadths of eggs produced by duiker ticks were greater than those of cattle ticks and unlike A. variegatum detached from cattle, the lengths and breadths of eggs of earlier and later ovipositions of this species detached from duiker were similar. Whereas deformed eggs characterized by circular shape and small size constituted a small percentage of eggs of cattle ticks, none was found among eggs of duiker ticks. The pre-oviposition, oviposition and eclosion periods, microscopic egg structure, embryonic development, hatching patterns and mortality rates of the eggs of ticks from both hosts were similar.     

Ticks associated with the three largest wild ruminant species in southern Africa

The objective of this study was to assess the host status of the three largest southern African wild ruminants, namely giraffes, Giraffa camelopardalis, African buffaloes, Syncerus caffer, and eland, Taurotragus oryx for ixodid ticks. To this end recently acquired unpublished data are added here to already published findings on the tick burdens of these animals, and the total numbers and species of ticks recorded on 12 giraffes, 18 buffaloes and 36 eland are summarized and discussed. Twenty-eight ixodid tick species were recovered. All stages of development of ten species, namely Amblyomma hebraeum, Rhipicephalus (Boophilus) decoloratus, Haemaphysalis silacea, Ixodes pilosus group, Margaropus winthemi, Rhipicephalus appendiculatus, Rhipicephalus evertsi evertsi, Rhipicephalus glabroscutatum, Rhipicephalus maculatus and Rhipicephalus muehlensi were collected. The adults of 13 species, of which the immature stages use small mammals as hosts, namely Haemaphysalis aciculifer, Hyalomma glabrum, Hyalomma marginatum rufipes, Hyalomma truncatum, Ixodes rubicundus, Rhipicephalus capensis, Rhipicephalus exophthalmos, Rhipicephalus follis, Rhipicephalus gertrudae, Rhipicephalus lounsburyi, Rhipicephalus lunulatus, Rhipicephalus pravus group and Rhipicephalus simus, were also collected.     

Effect of temperature on transtadial transmission of Theileria annulata in Hyalomma anatolicum anatolicum ticks.

The effect of temperature on the transtadial transmission of Theileria annulata in Hyalomma anatolicum anatolicum was studied. Variation in temperature (4-40 degrees C) had a significant effect on moulting rate of the ticks and transmission of theilerial parasites from nymphs to resultant adults. The temperatures above 40 degrees C and below 12 degrees C prevented moulting. Maximum infection levels were obtained in salivary glands of adult ticks when the infected engorged nymphs were incubated at 24-28 degrees C. The infection rate in salivary glands was assessed using a methyl green pyronin technique.     

Ixodid ticks on cattle belonging to small-scale farmers at 4 communal grazing areas in South Africa

Ixodid ticks were collected during the period September 1991 to August 1993 from cattle belonging to small-scale farmers utilising 4 communal grazing areas. Three of these were in North West Province and 1 in Mpumalanga province, South Africa. Ten tick species were collected in North West Province and 7 in Mpumalanga. The adults of Amblyomma hebraeum, Rhipicephalus appendiculatus and Rhipicephalus evertsi evertsi were most numerous in North West Province, while in Mpumalanga Boophilus decoloratus comprised more than 75% of the total population. Amblyomma hebraeum was present on all grazing areas, and heavy infestations of adults occurred during the period October to May on 1 of these. Few B. decoloratus were collected in North West Province, chiefly because the sampling method was inadequate, and most of these were present during early summer (October to December) and late summer and autumn (March to May). The initially low population of B. decoloratus in Mpumalanga increased substantially towards the conclusion of the survey, probably because of the cessation of dipping. Boophilus microplus was present in small numbers on 2 grazing areas in the North West Province. Adult Hyalomma marginatum rufipes reached peak numbers from December to February and Hyalomma truncatum from February to April in the North West Province. Only H. marginatum rufipes was collected in Mpumalanga. Rhipicephalus appendiculatus was present on all the grazing areas, with most adults present from December to April. Most adult Rhipicephalus evertsi evertsi were collected from September to April and Rhipicephalus simus was present during the period October-April.     

Ticks and hemoparasitoses of livestock in Senegal. III. The Northern Sudan area

The authors describe the results of a study on ticks and hemoparasitoses of cattle and small ruminants in the Senegalese north-sudanian area. For 15 months, 40 bovine, 40 sheep and 40 goats received a routine dipping treatment, aimed at the determination of the tick population dynamics together with an accurate localization of the preferential sites for the different species. The following parasites were collected from the animals: Hyalomma marginatum rufipes, H. truncatum, Rhipicephalus lunulatus, Rh. e. evertsi, Rh. sulcatus, Rh. senegalensis, Boophilus decoloratus. Joint studies were conducted on the hemoparasites using blood smear and splenectomy. Among bovine, Anaplasma marginale, Ehrlichia bovis, Theileria mutans, Th. velifera, Trypanosoma congolense, T. brucei and microfilariae from Setaria labiatopapillosa were observed. Babesia bigemina was observed after a splenectomy. In small ruminants, the detected infections are brought about by A. ovis, Th. ovis and T. vivax. Hematocrite value of apparently healthy animals are studied as well as the seasonal variation of this hematological factor.