In this article, the main amphistome species infecting domestic and wild ruminants in East and Southern Africa, their snail intermediate hosts and epidemiological features are reviewed and discussed. Twenty-six amphistome species belonging to nine genera from three families occur in domestic and wild ruminants in the region under review and over 70% of them belong to the genera
Amphistomosis is a disease of domestic and wild ruminants caused by digenetic trematodes of the superfamily Paramphistomoidea Fischoeder, 1901 (Lotfy et al.
A wide range of gastropods belonging to the genera
In this review, to avoid confusion, genera of parasites and snail hosts have been abbreviated using the first three letters of the genus name and these include: for amphistomes –
Checklist of amphistome species and their ruminant and snail intermediate hosts reported in east and southern African countries.
Family | Species | Country reported | Domestic ruminant hosts | Wild ruminant hosts | Intermediate snail hosts | References |
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Paramphistomidae Fischoeder 1901 | Zambia | – | Blue wildebeest ( |
Not yet known | Eduardo |
|
Kenya, South Africa and Tanzania | Cattle ( |
Buffalo ( |
Not yet known | Dinnik |
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Angola, Kenya, Mozambique, South Africa, Zambia and Zimbabwe | Cattle, goats and sheep | Buffalo, Blue wildebeest, Bushbuck ( |
6, Porter |
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Kenya, Tanzania, Uganda and Zimbabwe | Cattle, goats and sheep | Buffalo, Hartebeest, Impala and Sable antelope | Not yet known | Eduardo |
||
Kenya | Cattle | - | Eduardo |
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Paramphistomidae | Angola, Botswana, Kenya, Lesotho, Mozambique, South Africa, Tanzania, Uganda, Zambia and Zimbabwe | Cattle, goats and sheep | Bohor reedbuck ( |
Dinnik |
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Kenya, South Africa, Tanzania, Uganda, Zambia and Zimbabwe | Cattle, goats and sheep | Bohor reedbuck, Buffalo, Kudu, Impala, Puku ( |
Eduardo |
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Botswana, Kenya, Namibia, South Africa, Tanzania, Zambia and Zimbabwe | Cattle, goats and sheep | Blue wildebeest, Buffalo, Bushbuck, Eland, Gemsbok, Kudu, Hartebeest, Impala, Kafue lechwe, Puku, Reedbuck, Roan antelope, Sable antelope, Thomson’s gazelle, Topi, Tsessebe, Waterbuck | Dinnik |
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Angola, Kenya, Tanzania, Uganda, Zambia and Zimbabwe | Cattle, sheep and goats | Buffalo | Dinnik |
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Tanzania, Zambia and Zimbabwe | Cattle | Buffalo, Blue wildebeest, Eland, Kafue lechwe, Reedbuck, Roan antelope, Topi, Waterbuck | Not yet known | Eduardo |
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Angola, Kenya, Malawi, Mozambique, South Africa, Tanzania, Uganda, Zambia and Zimbabwe | Cattle, goats and sheep | Blue wildebeest, Bohor reedbuck, Buffalo, Bushbuck, Common duiker ( |
Not yet known | Ortlepp |
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Kenya, Malawi, South Africa, Tanzania, Uganda and Zambia | Cattle | Buffalo and Impala | Not yet known | Anderson |
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Kenya, Tanzania, Uganda, Zambia and Zimbabwe | Cattle | Kudu, Hartebeest, Impala and Sable antelope | Not yet known | Von Roth & Dalchow |
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Uganda | – | Buffalo, Hartebeest and Oribi ( |
Not yet known | Eduardo |
||
Botswana, South Africa, Zambia and Zimbabwe | Cattle | Buffalo, Hartebeest, Kafue lechwe, Kudu and Roan antelope | Not yet known | Sey & Graber |
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Kenya | Cattle | – | Dinnik |
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Gastrothylacidae Stiles and Goldberger 1910 | Zimbabwe | – | Hartebeest and Bongo ( |
Not yet known | Sey |
|
Botswana | Cattle | – | Not yet known | Dube et al. |
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Kenya, Malawi, Tanzania and Zimbabwe | Cattle and sheep | Buffalo, Reedbuck, Roan antelope, Sitatunga, Topi and Waterbuck | Dinnik 1964a; Von Roth & Dalchow 1967; Jooste |
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Kenya and South Africa | Cattle | Buffalo, Bushbuck and Imbabala ( |
Laidemitt et al. |
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Kenya and Tanzania | Cattle, goats and sheep | Bohor reedbuck, Buffalo, Bushbuck, Eland, Kafue lechwe, Roan antelope and Waterbuck | Dinnik 1964a; Laidemitt et al. |
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Kenya and Zambia | Cattle | Bushbuck, Sable antelope, Topi and Waterbuck | Dinnik |
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Kenya, Mozambique, South Africa, Tanzania, Zambia and Zimbabwe | Cattle, goats and sheep | Bohor reedbuck, Buffalo, Bushbuck, Kafue lechwe, Hartebeest, Reedbuck, Roan antelope, Sitatunga, Topi and Waterbuck | Not yet known | Dinnik 1964a; Ortlepp |
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Gastrothylacidae | South Africa and Zambia | Cattle, goats and sheep | Buffalo, Kafue lechwe and Sitatunga | Not yet known | Ortlepp |
|
Choerocotyloididae Yamaguti 1971 | Zambia | Cattle | Reedbuck, Red lechwe ( |
Not yet known | Eduardo |
|
Stephanopharyngidae Stiles and Goldberger 1910 | Angola, South Africa, Tanzania, Zambia and Uganda | Cattle | Blue wildebeest, Buffalo, Kafue lechwe, Reedbuck, Roan antelope and Waterbuck | Not yet known | Eduardo |
In this paper, we review the information available to date on amphistome species infecting domestic and wild ruminants in east and southern African countries, the snail intermediate hosts, as well as the epidemiology of amphistomosis and available control options.
Reported amphistome species and their respective domestic and wild ruminant hosts in east and southern African countries are shown in
Twenty-six species occur in domestic and wild ruminants in the area under review. Seventy-seven per cent of them (20/26) belong to
The majority of the species (76.9%) are shared between domestic and wild ruminant hosts and approximately 12% of them have not been documented in domestic ruminants as yet (
Mixed farming systems of cattle and game, particularly antelope, have become an important agricultural activity in most east and southern African countries. In addition, there has been the creation of Transfrontier Conservation Areas (TFCAs) involving many African countries, particularly in Southern Africa, resulting in increased livestock–wildlife interface areas. Therefore, domestic and wild animals are coming into ever more intimate contact in many interface areas, particularly in rural areas at the edges of the TFCAs and in farms practising mixed cattle and game farming, thus promoting the possibility of parasite exchange. These observations are important when considering the different options for their control. For instance, Phiri et al. (
The current review shows that only nine (34.6%, 9/26) amphistome species (
Data under review show that most of the known amphistome species have unknown snail hosts (65.4%, 17/26). The snail hosts of four
The epidemiology and prevalence of amphistomosis depend on several factors. These include the species of definitive and intermediate hosts (Rolfe et al.
Data on amphistome infection prevalence are scarce for the reviewed countries and are currently only available from six countries (
Prevalence of amphistomes in ruminants in east and southern African countries based on faecal egg and fluke counts.
Host | Location | Total examined | Positive | Prevalence (%) | 95% CI | Publication year | References |
---|---|---|---|---|---|---|---|
Cattle | Tanzania | 450 | 283 | 62.9 | 58.2–67.3 | 2015 | Nzalawahe et al. |
Cattle | Tanzania | 241 | 90 | 37.3 | 31.3–43.8 | 2014 | Nzalawahe et al. |
Cattle | Uganda | 233 | 158 | 67.8 | 61.3–73.7 | 2011 | Howell |
Cattle | Kenya | 344 | 108 | 31.4 | 26.6–36.6 | 2010 | Kanyari et al. |
Cattle | Zambia | 50 | 38 | 76.0 | 61.5–86.5 | 2008 | Yabe et al. |
Cattle | Zambia | 268 | 96 | 35.8 | 30.1–41.9 | 2007 | Phiri et al. |
Cattle | Zambia | 101 | 33 | 32.7 | 23.9–42.8 | 2007 | Phiri et al. |
Cattle | Tanzania | 482 | 302 | 62.7 | 58.2–67.0 | 2006 | Keyyu et al. |
Cattle | Zambia | 709 | 366 | 51.6 | 47.9–55.4 | 2006 | Phiri et al. |
Cattle | Tanzania | 301 | 168 | 55.8 | 50.0–61.5 | 2005 | Keyyu et al. |
Cattle | Zimbabwe | 16 264 | 4790 | 29.5 | 28.8–30.2 | 2005 | Pfukenyi et al. |
Cattle | Zimbabwe | 12 472 | 6697 | 53.7 | 52.8–54.6 | 1999 | Vassilev |
Cattle | Zimbabwe | 796 | 490 | 61.6 | 58.1–64.9 | 1994 | Vassilev |
Cattle | Kenya | 1878 | 481 | 25.6 | 23.7–27.7 | 1993 | Waruiru et al. |
Goats | Kenya | 33 | 4 | 12.1 | 4.0–29.1 | 2009 | Kanyari et al. |
Sheep | Kenya | 54 | 16 | 29.6 | 18.4–43.8 | 2009 | Kanyari et al. |
Buffalo | Uganda | 10 | 6 | 60.0 | 27.4–86.3 | 2011 | Howell |
Kafue lechwe | Zambia | 22 | 11 | 50.0 | 28.8–71.2 | 2002 | Kock et al. |
Cattle | Uganda | 32 | 27 | 84.4 | 66.5–94.1 | 2011 | Howell |
Cattle | Zambia | 50 | 48 | 96.0 | 85.1–99.3 | 2008 | Yabe et al. |
Cattle | Zimbabwe | 3225 | 822 | 25.5 | 24.0–27.0 | 2004 | Dube et al. |
Cattle | Zimbabwe | 1377 | 429 | 31.2 | 28.7–33.7 | 2002 | Dube et al. |
Goats | Zimbabwe | 3000 | 60 | 2.0 | 1.5–2.6 | 2010 | Dube et al. |
Sheep | Zimbabwe | 1000 | 60 | 6.0 | 4.7–7.7 | 2010 | Dube et al. |
Kafue lechwe | Zambia | 8 | 7 | 87.5 | 46.7–99.3 | 2012 | Munang’andu et al. |
Wildebeest | Zambia | 6 | 4 | 66.7 | 24.1–94.0 | 2012 | Munang’andu et al. |
Kafue lechwe | Zambia | 65 | 65 | 100.0 | 93.1–99.9 | 2011 | Phiri et al. |
Kafue lechwe | Zambia | 40 | 40 | 100.0 | 89.1–99.8 | 2010 | Munyeme et al. |
Impala | South Africa | 46 | 41 | 89.1 | 75.6–95.9 | 1983 | Anderson |
Studies on animal-breed predisposition to amphistome infection are limited. Indigenous cattle breeds were observed to have a significantly higher prevalence and intensity than the exotic breeds and crosses in Kenya and Uganda (Howell
Adult domestic ruminants are reported to have a significantly higher prevalence compared with young animals (Howell
Animal grazing area and/or habitat is significantly associated with prevalence and intensity of amphistomes in domestic ruminants (Howell
The prevalence in domestic ruminants as measured by coprology follows a seasonal pattern with an increase towards the end of the dry season and a peak during the wet months of the year (Keyyu et al.
Development of amphistomes into adults takes 5–9 months (Dinnik & Dinnik
Adult flukes are not associated with clinical amphistomosis (Mavenyengwa, Mukaratirwa & Monrad
Clinical amphistomosis is caused by the immature flukes that lodge in the first 3 m of the small intestine (Mavenyengwa et al.
Diagnosis of amphistomes in live animals is still dependent on faecal detection of eggs (Rieu et al.
The clinical diagnosis of amphistomosis remains challenging as immunological techniques are usually not conclusive (Horak
The available epidemiological information on amphistomes of ruminants in the area under review can be used to design appropriate integrated control measures. Options available for the control of amphistome infections are mainly based on chemical treatment, non-chemical management practices and immunological control.
Chemical control involves treatment with a product that is effective against both adult and immature flukes. Oxyclozanide given twice, three days apart, has a high efficacy against both adult and juvenile amphistomes (Rolfe & Boray
Even though it is not of direct benefit to the animal, treatment against mature amphistomes will prevent egg laying and thus reduce pasture contamination (Horak
Disease epidemiology indicates that large burdens of immature amphistomes are expected during the dry season. As adult animals are resistant to the pathogenic effects of the migrating immature amphistomes, the target for treatment would be young animals being exposed to the infection for the first time (Pfukenyi et al.
The efficacy of medicinal plant extracts against amphistomes has recently been evaluated. The ethanol extract of
Chemical control of the snail hosts through application of molluscicides such as niclosamide may also be done. To achieve cost-effective control, this type of control should be done during the peak transmission period to reduce numbers of infected snails and cercarial shedding. Thus, the application could be done during the mid-dry and towards the end of the dry season (Pfukenyi et al.
Hafeez and Rao (
The best preventive method against amphistome infections is to keep domestic ruminants from infected pastures (Pfukenyi et al.
Twenty-six amphistome species belonging to nine genera from three families occur in domestic and wild ruminants in the area under review and seven snail species belonging to four genera from two families act as their intermediate hosts. Eighty-five per cent of the amphistome species are shared between domestic and wild ruminant hosts. Some snails are intermediate hosts of amphistome species belonging to the same genus or to different genera – a phenomenon not yet fully elucidated. Only nine (34.6%) of the amphistome species have known snail intermediate hosts, while most (65.4%) have unknown hosts. The epidemiology of amphistomosis depends on the species of definitive and intermediate hosts and the potential of the flukes to infect these hosts, the topography and biological potential of the snail hosts, the management systems of the definitive host and their grazing habits and climatic factors. Based on current epidemiological information, the strategic anthelmintic treatment against mature amphistomes should be given in adult animals at the end of the rainy or early dry season. The anthelmintic treatment in young animals against immature amphistomes should be administered during the mid-dry and towards the end of the dry season. Further research is necessary to determine the economic importance of amphistomosis, amphistome–snail associations, efficacy of different anthelmintics and to develop diagnostic tests that can detect prepatent infections in the definitive host.
The authors would like to thank the anonymous reviewers whose suggestions improved the manuscript.
The authors declare that they have no financial or personal relationships that may have inappropriately influenced them in writing this article.
Both authors contributed equally in the writing of this manuscript.