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Tropical Life Sciences Research, 27(1), 135–144, 2016 Effectiveness of Ivermectin and Albendazole against Haemonchus
contortus in Sheep in West Java, Indonesia
1Silvia Puspitasari, 1Achmad Farajallah, 2Erni Sulistiawati and 3,4Muladno
1Animal Bioscience, Department of Biology, Faculty of Mathematics and Science,
2Veterinary Technician Diploma Program, 3Department of Animal Production and Technology, Faculty of Animal Science, Bogor Agricultural University, Bogor 16680, West Java, Indonesia 4Directorate General of Livestock and Animal Health, Ministry of Agriculture of Republic of
Indonesia, South Jakarta, Indonesia
Abstrak: Memberikan dos separuh antelmintik merupakan suatu kaedah untuk mengesan
daya tahan parasit yang menjangkiti haiwan ruminan kecil. Apabila satu antelmintik tidak
berkesan dalam kambing biri-biri asal daripada Indonesia, satu kombinasi antelmintik
daripada kelas kimia berbeza dengan cara tindakan berbeza diberikan sebagai satu
strategi pengawalan parasit alternatif. Kajian ini membezakan kemujaraban antelmintik
ivermectin (IVM) dan albendazole (ABZ) yang diberikan secara berasingan ataupun
separuh dos ataupun diberikan bersama kepada kambing biri-biri yang dijangkiti secara
semula jadi dengan Haemonchus contortus. Dua belas kambing biri-biri daripada Bogor,
Jawa Barat, Indonesia telah dibahagikan kepada enam kumpulan rawatan: dos separuh
IVM, dos penuh IVM, dos separuh ABZ, dos penuh ABZ, kombinasi IVM + ABZ, dan
kawalan. Kemujaraban rawatan telah ditentukan menggunakan ujian pengurangan
pengiraan telur tinja (FECRT) pada hari 0 (pra-rawatan) dan pasca-rawatan pada hari-hari
7, 14, 21, 28, 35, dan 42. Kemujaraban separuh dos IVM, dos penuh IVM, dos separuh
ABZ, dos penuh ABZ, dan rawatan kombinasi bernilai daripada –1900% hingga 100%,
99% hingga 100%, –167% hingga 100%, –467% hingga 89%, dan –200% hingga 100%,
masing-masing. FECRT untuk separuh dos IVM, dos separuh ABZ, dos penuh ABZ
menunjukkan bahawa H. contortus mempunyai daya tahan terhadap separuh dos IVM
dan ABZ. Dos penuh IVM berkesan terhadap H. contortus. Rawatan kombinasi lebih
berkesan terhadap H. contortus berbanding menggunakan ABZ sahaja.

Kata kunci: Ivermectin, Albendazole, Haemonchus contortus, Jawa Barat Indonesia
Abstract: Administering a half dose of an anthelmintic is a simple method for detecting
resistance in parasites infesting small ruminants. When a single anthelmintic fails in native
sheep from Indonesia, a combination of anthelmintics from different chemical classes with
different modes of action are administered as an alternative parasite-control strategy. This
study compared the anthelmintic efficacy of ivermectin (IVM) and albendazole (ABZ) given
either separately as a single dose or half dose or co-administered to sheep naturally
infected with Haemonchus contortus. Twelve sheep from Bogor, West Java, Indonesia
were divided into the following six treatment groups: half-dose IVM, full-dose IVM, half-
dose ABZ, full-dose ABZ, combined IVM + ABZ, and control. The treatment efficacy was
determined using the faecal egg count reduction test (FECRT) at day 0 (pre-treatment)
and post-treatment at days 7, 14, 21, 28, 35, and 42. The efficacies of half-dose IVM, full-
dose IVM, half-dose ABZ, full-dose ABZ, and the combination treatment ranged from
–1900% to 100%, 99% to 100%, –167% to 100%, –467% to 89%, and –200% to 100%,
respectively. The FECRT for the half-dose IVM, half-dose ABZ, full-dose ABZ showed that
*Corresponding author: [email protected] Penerbit Universiti Sains Malaysia, 2016 Silvia Puspitasari et al. H. contortus is resistant to half-dose IVM and ABZ. Full-dose IVM was effective against
H. contortus. The combined treatment was more effective against H. contortus than ABZ
alone.
Keywords: Ivermectin, Albendazole, Haemonchus contortus, West Java Indonesia
INTRODUCTION

In the tropics, gastrointestinal nematodes are a major problem in small
ruminants, and they cause disease, death, and decreased production of milk,
meat, and wool (Bekele et al. 1992; Zainalabidin et al. 2014). The barber pole
worm, Haemonchus contortus, causes haemonchosis, which results in anaemia
and digestive disorders. The adult worms live free in the abomasum of the host
and attack the mucosa by piercing with their buccal lancets to suck the blood.
Female worms produce eggs that are excreted in the faeces into the
environment, and the larvae orally infect the host as the ruminants feed on grass
(Monnig 1950).
In small ruminants, gastrointestinal nematodes can generally be controlled using broad-spectrum anthelmintics. Widely available commercial anthelmintics commonly used by farmers include macrocyclic lactones (avermectin [AVM] and milbemycins [MLs]), benzimidazole (BZD), and imidazothiazoles (levamisole [LEV] and hydropyrimidines [pyrantel/morantel]). Ivermectin (IVM) is a macrocyclic lactone with broad activity against gastrointestinal nematodes (Egerton et al. 1979) and ectoparasites (Campbell et al. 1983). IVM acts by binding the α-subunit of glutamate-gated chloride channel receptors (GluCl) in nerve synapses (Wolstenholme 2011), which inhibits nematode feeding, fecundity, and motility (Yates et al. 2003). Albendazole (ABZ) is a BZD with a methyl carbamate group that is effective against lung worms (McKellar & Scott 1990), gastrointestinal nematodes, tapeworms, and liver flukes (Campbell 1990). BZD acts by binding to β-tubulin, which inhibits dimerisation with α-tubulin during microtubule formation in nematode cells (Lacey 1990; Wolstenholme 2011). The intensive use of anthelmintics has led to the development of anthelmintic resistance in small ruminants (Kaplan 2004; Wolstenholme et al. 2004). Resistance is considered present when a portion of a population is able to tolerate doses of a compound that are effective against other populations of the same species (Prichard et al. 1980). IVM-resistant H. contortus has been reported in Australia (Le Jambre 1993), Kenya (Mwamachi et al. 1995; Waruiru et al. 1998), South Africa (van Wyk et al. 1989), and Brazil (Echevarria et al. 1991; Vieira et al. 1992). BZD-resistant H. contortus has been reported in Australia (Green et al. 1981), Malaysia (Rahman 1994), India (Uppal et al. 1992), France (Kerboeuf et al. 1988; Hubert et al. 1991), Kenya (Mwamachi et al. 1995), South Africa (Berger 1975), and Brazil (Echevarria et al. 1991). The resistance problem is compounded by the fact that many parasite populations are resistant to more than one class of anthelmintic. It has been proposed that the combined use of anthelmintics might be more effective against gastrointestinal nematodes when a single anthelmintic has failed. In addition, anthelmintic combinations slow Ivermectin and Albendazole against Haemonchus contortus the development of resistance (Wolstenholme et al. 2004; Coles 2005; Leathwick et al. 2009). This study compared the anthelmintic efficacy of IVM and ABZ given separately in a single dose and half dose or co-administered to sheep naturally infected with H. contortus. MATERIALS AND METHODS
Animal
Twelve sheep (age 3–4 months, liveweight 13–20 kg) from Bogor, West Java,
were studied. The management system was intensive, the sheep were housed
colonially, fed hay, and water was provided ad libitum.
Experimental Design
The sheep were divided randomly into six experimental groups (Table 1). Faecal
samples were collected directly from the rectums of the sheep at days 0 (pre-
treatment) and at days 7, 14, 21, 28, 35, and 42 post-treatment.
Table 1: The anthelmintic treatment.
Route of administration ½ mL/50 kg liveweight 1 mL/50 kg liveweight ½ mL/5 kg liveweight 1 mL/5 kg liveweight Combined (IVM + ABZ) Subcutaneous+oral (½ mL/50 kg + ½ mL/5 kg) liveweight
Faecal Egg Counts (FEC)
The FEC were determined by a modified McMaster technique that is accurate to
50 eggs per gram. The total number of H. contortus eggs counted in two
chambers of McMaster slide was multiplied by 50 to obtain the number of egg
per gram (epg) of faeces. The FEC were plotted in curves to calculate the
p-value of the regression. The identification of H. contortus eggs was based on
the size, shape, and development stage of the eggs (Foreyt 2001).
Anthelmintic
The anthelmintics that were used for treatment were IVM (Ivomec Super, Merial,
Brazil) and ABZ (Kalbazen®-SG-Albendazole 19 mg/mL, PT. Kalbe Farma,
Bekasi, Indonesia).
Data Analysis
Susceptibility to the various anthelmintic drugs was quantified using the faecal
egg counts reduction (FECR) method. The FECR was calculated according to
the recommendations of the World Association for the Advancement of
Veterinary Parasitology (Coles et al. 1992) to evaluate the effectiveness of each
Silvia Puspitasari et al. anthelmintic treatment, using the following formula described by Kochapakdee et al. (1995) and McKenna (2006): FECRi (%) = 100 × [1 – (Ti/T0)] where FECRi is FECR on days i, Ti is the arithmetic mean faecal egg counts after
treatment (day 7, 14, 21, 28, 35, and 42), and T0 is the arithmetic mean of the
faecal egg counts before treatment (day 0) in the treated group. Anthelmintic
effectiveness was based on the FECR (%) and the lower 95% confidence limits.
If the FECR percentage of an anthelmintic treatment was less than 95% and the
lower 95% confidence limit for the reduction was less than 90%, resistance was
considered to be present. If only one of the two criteria was met, resistance was
suspected.
RESULTS
Full-dose IVM completely decreased the number of H. contortus eggs on day 7.
However, the number of eggs was significantly different and actually increased in
the control group and the group that received the full-dose ABZ. The anthelmintic
combination decreased the number of eggs until day 35 (Fig. 1).
Figure 1: The H. contortus faecal egg count (epg) for each treatment, before (day 0) and
after (day 7 to 42) treatment.
Note: Control and full-dose ABZ; p<0.05.
Table 2 summarises the results of the FECR. The efficacy of half-dose IVM, full-dose IVM, half-dose ABZ, full-dose ABZ, and the combined treatment ranged from –1900% to 100%, 99% to 100%, –167% to 100%, –467% to 89%, and –200% to 100%, respectively. Full-dose IVM had the greatest efficacy at

Ivermectin and Albendazole against Haemonchus contortus 99%–100%. The low overall percentage reduction showed that H. contortus is resistant to IVM and ABZ. Table 2: FECR (%) and anthelmintic efficacy against H. contortus in sheep.
Notes: FEC = faecal egg counts; FECR = faecal egg count reduction; IVM = ivermectin; ABZ = albendazole; Combination = half-dose ivermectin + half-dose albendazole; CL = confidence limit.
DISCUSSION
Faecal Egg Counts (FEC)
The FEC from each group prior to treatment (day 0) and after treatment (day 7 to
42) are shown in Figure 1. Based on the p-value, the significant treatments were
the control and full-dose ABZ groups. The control group demonstrated an
increase in the number of H. contortus eggs that was significant (p<0.05). The
egg counts increased on days 21 and 35 in the controls because it takes
approximately 18–21 days for H. contortus larvae to mature and produce eggs
(Monnig 1950). Adult female worms can lay an average of 6.582 eggs per day
(Coyne et al. 1991). By day 14, the control treatment had decreased the number
of H. contortus eggs. According to Dobson et al. (2012), counts of untreated
control animals may decrease because of density-dependent constraints on
fecundity that are exacerbated by any incoming infection in the period between
the pre- and post-treatment counts.
Full-dose ABZ treatment increased the number of H. contortus eggs to a level that was significant (p<0.05). Cezar et al. (2010) showed that a full-dose ABZ treatment increased the number of H. contortus eggs by day 12. Although the response to the full-dose IVM treatment was non- significant, Figure 1 shows that the egg excretion dropped to 0 on day 7 after the administration of full-dose IVM. This result is in agreement with research from Yacob et al. (2009) that showed that IVM decreased the egg count to 0 on day 7 until day 21. Other studies have shown that IVM treatment decreased the Silvia Puspitasari et al. number of H. contortus eggs on days 5 (McKenna & Watson 1987), 10
(Borgsteede 1993), and 14 (Gogolewski et al. 1995).
Faecal Egg Count Reduction Test (FECRT)
Giving half the dose of an anthelmintic is recommended as a simple method for
the early detection of resistance (Hughes et al. 2005). According to Smith et al.
(1999), when given at below the recommended dose, the anthelmintic has a
shorter half-life. The parasite death rate due to the drug is seen as an
instantaneous decrease with the administration of an anthelmintic. On days 7
and 14, the IVM status was resistant, but by day 21, the anthelmintic status
became susceptible. Some important factors to be considered in the diagnosis of
anthelmintic resistance and the interpretation of results are the route of
administration and pharmacokinetic behaviour (Canga et al. 2009), host nutrition
(Coop & Kyriazakis 2001), and the host immune system and age (Lanusse &
Prichard 1993). Subcutaneous administration delays the absorption of IVM from
the injection site, resulting in the prolonged presence of the drug in the
bloodstream (Canga et al. 2009). Depending on the host nutrition, protein content
affects the development rate of immunity against parasitic infections, according
to Gibson (1983). Protein deficiency causes damage to T-lymphocytes (Beisel
1982). As demonstrated by Gill et al. (1993), T-lymphocytes play an important
role in combatting haemonchosis in sheep. Sheep under the age of 6 months
have very low protection from gastrointestinal nematodes (Lloyd & Soulsby
1987). The half-dose of ABZ was not effective against H. contortus. The activity
of ABZ depends on the ability of the drug to reach and sustain sufficient
concentrations at the site of infection (Lanusse & Prichard 1993).
The full-dose IVM treatment is very effective against gastrointestinal nematodes that are resistant to ABZ, including H. contortus (George et al. 2011). The efficacy of a drug is also associated with the route of administration. The subcutaneous injection of IVM results in higher plasma IVM concentrations for a longer duration (Alvinerie et al. 1998). IVM paralyses the neuromuscular system in the target tissue by increasing the permeability of the plasma membrane to chloride ions (Cl ). This causes hyperpolarisation and inhibits pharyngeal pumping, feeding, parasite spawning, and muscle motility. The pharynx is a muscular digestive organ that acts in nutrient ingestion and excretion and regulates turgor pressure in the parasite. Paralysis of the pharynx reduces the energy reserves of the parasites (Sangster & Gill 1999) and inhibits feeding by blocking pharyngeal pumping (Geary et al. 1993). Paralysis of the uterine muscles in female worms can suppress egg production and the release of eggs that are already present in the uterus. In addition, IVM can sterilise female nematodes in several hosts without killing them (Coles 2005). Le Jambre (1993) reported that IVM suppressed the fecundity of female H. contortus. IVM paralyses the somatic muscles in the parasite mid-body, reducing parasite motility and facilitating its expulsion from host intestinal tract (Sangster & Gill 1999). In contrast, full-dose ABZ was less effective against H. contortus. George et al. (2011) also reported the low efficacy of ABZ. The mechanism of resistance involves a reduction in the binding affinity of ABZ to tubulin (Sangster et al. 2002) due to a mutation in β-tubulin (Kohler 2001). In H. contortus, selection for Ivermectin and Albendazole against Haemonchus contortus resistance is enhanced by the high biotic potential. Their fecundity can enable small populations of resistant worms to become large populations in a short amount of time, especially if the climate is favourable for the free-living stages (Craig 1993). In this study, the farmer used ABZ as worm therapeutics for several years. Using the same class of drugs for several years (Coles 2005) ensures that the worms that survive treatment will have a greater chance than susceptible worms to contribute to the next generation. In this study, the combined treatment with IVM and ABZ was effective against H. contortus from days 7 to 21; then, resistance was seen on days 28 to 42, suggesting that H. contortus is cross-resistant to the combination treatment. According to Prichard et al. (1980), cross-resistance occurs when a population can fight anthelmintics in different chemical groups that have different modes of action. Miller and Craig (1996) reported that the combination of IVM and ABZ was more effective against H. contortus than either given alone. Multiple-drug resistance in H. contortus has also been reported (Traversa et al. 2007; Cezar et al. 2010). CONCLUSION
The percentage reductions in the faecal egg count in the half-dose IVM, half-
dose ABZ, and full-dose ABZ groups showed that H. contortus is resistant to half-
dose IVM and ABZ. The full-dose IVM treatment was 99%–100%, effective
against H. contortus. The combined treatment was more effective against
H. contortus than ABZ alone.
ACKNOWLEDGEMENT
Thanks are due to the Directorate of General Higher Education (DIKTI) for the
scholarship Beasiswa Unggulan (BU) DIKTI 2012. The cooperation and
assistance of the farmers who agreed to take part in this study are gratefully
acknowledged.
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