Strategic Management of a Clinical Case of Recurrent Caseaous Lymphadenitis in a Goat Farm

A 3 year old female Saanen cross doe was presented to the University Veterinary Hospital, Universiti Putra Malaysia with the complaint of swelling on the lower right mandible, which was first noticed three weeks prior to presentation. Clinical history revealed that the farm previously had CLA and was depopulated in 2008 in order to reduce the risk of spread of the disease. However, it was observed that the disease reoccurred after three years.

Physical examination revealed a round firm, non-movable and non-painful mass on the ventral side of the mandible and an enlarged sub mandibular lymph node which was 1.5 x 1.5 centimeter in size (Figure 1). Vital parameters revealed that the doe had rectal temperature of 39.2 ºC, respiratory rate of 36 cycles per minute and pulse rate 72 beats per minute, respectively.

The swollen area was aseptically prepared and fine needle aspiration biopsy was attempted; however, there a caseaous exudate oozed out immediately the needle was removed (Figure 2). The exudate was collected in a plain tube for bacterial culture and identification while blood sample was collected for complete blood count and serum biochemistry. The result of the bacterial culture revealed a heavy growth of Corynebacteria pseudotuberculosis, while complete blood count showed leukocytosis and neutrophilia with a regenerative left shift and monocytosis thus, suggestive of an ongoing inflammatory process.

Figure 2: Excised Caseaous exudate and fine needle aspiration biops

The doe and other two showing clinical manifestation of CLA were culled in order to limit the spread of the disease to other healthy animals in the farm.

Caseaous lymphadenitis (CLA) continues to pose a serious problem to the small animal industries, thus limiting their economic profitability. It has been observed that the sustained marketing and movement of small ruminants from one country to the other without the use of adequate biosecurity measures greatly limit the control and prevention of CLA (de Sá Guimarães et al., 2011). Thus, maintaining the prevalence of CLA at its peaks, indicating the need for adopting a sustainable control measures. It is worthy of note, that difficulty abounds in development and application of an effective diagnostic plan. It is therefore important to have effective immunogens which can be use in vaccination (de Sá Guimarães et al., 2011).

Cases of CLA in humans are rare and if reported in most cases it is related to exposure as a result of contact with infected animals. However, cases of CLA in humans due to the ingestion of raw cow and goat meat have been reported (Peel et al., 1997). In addition, about 25 cases of human infection have also been reported thus, indicating the zoonotic potential of CLA. Mills et al. (1997) reported a case of suppurative granulomatous lymphadenitis in a boy who has contact with farm animals. This finding validates the zoonotic implication of CLA and the need to develop an effective biosecurity measures to guard against infections to humans. Furthermore, Peel et al. (1997) in their review also reported that about 22 cases of human CLA is characterized by lymphadenitis, abscesses and other similar symptoms. In all cases, patients were treated with antibiotics and the affected lymph nodes surgically removed.

The clinical management of CLA revolves around early detection of the disease in a herd and culling of infected animals showing clinical manifestation of the disease. Due to the chronic nature of the disease, the tendency of the disease to spreading rapidly in the herd without the farmer knowing until the development of clinical manifestation is high (Osman et al., 2015). One of the major challenges in the management of CLA is attributed to the fact that many farmers and animal owners have little or no knowledge of the disease thus, facilitating the rapid spread of the disease among the herd. For instance, in Malaysia only about 14.8% of the farmers have knowledge of CLA (Osman et al., 2012). CLA disease causes significant economic loss to small ruminant industry, therefore, it is important to design measures that will aim at reducing the rate of spread of the disease.

For instance, bacteria induced caseation necrosis of the lymph nodes is one of the major manifestation of CLA in small ruminants and the organism have been known to persist within the infected lymph node. The most frequently observed clinical manifestation is abscess formation in the peripheral lymph nodes, subcutaneous tissue and involvement of the visceral organs (Dorella et al., 2006). This is in agreement with the finding of this case report, because clinical history revealed a round firm swelling on the ventral side of the mandible and caseaous exudate upon excision (Figure 2). Furthermore, it has been observed that the abscess can persist for about two to three years containing the viable organism, thus, serving as a potential source of reinfection of the flocks (de Sá Guimarães et al., 2011).

Because CLA is a disease of great economic and zoonotic importance, there is the need to design an effective strategic plan for its control and eradication in areas where the disease is endemic. Such strategies can involve measures such as reducing the number of infected animals to such a level that it doesn’t pose a significant threat to animal welfare and public health. Other measures such as test and slaughter method should also be employed. The key to successful eradication of CLA in an endemic area involves the implementation of an active surveillance system supported by a fully equipped laboratory (Osman et al., 2015). Given the nature of the spread of CLA, the treatment of the disease is in effective and expensive. The best strategy adopted so far for the prevention and control of the disease in countries where the prevalence of the disease is high is through vaccination against the causative organism and this have however proven to give a very good result (Dorella et al., 2006; Roslindawani et al., 2016). An effective strategy however should be based on frequent clinical inspection, and serologic testing of all animals in the flock from time to time, including the recently purchased animals, and those that have been returned to the herd while culling those that are serologically positive or those showing clinical disease (de Sá Guimarães et al., 2011). This is because it has been observed that once the animal has been infected, it is difficult to completely eradicate the causative organism. For instance, in an eradication programme, there is need to accurately measure the predictive value of the test used in detecting the presence of CLA before a decision of culling an infected animal is made. This is because, increase or decrease in the prevalence of the disease affects the outcome of the test and thus can led to poor judgement which invariably results in under or over reporting the occurrence of the disease in a herd (Dercksen et al., 2000). In addition, given the important role played by subclinically infected animals in the introduction and spread of CLA into a herd, serological diagnosis has proven to be very useful in the control and eradication of CLA. Serological test such as compliment fixation test (CFT), ELISA, hemolysis inhibition test and immunodiffusion test are usually employed in the diagnosis of CLA. In spite of the limitations of these tests, ELISA has proven to be an exceptionally versatile tool in the control and eradication of CLA (Cetinkaya et al., 2002).

The implementation of biosecurity procedures in all flocks must especially during the introduction of new animals have showed reduction in the rate of infection (Campbell et al., 1982). This is because; the focal point of entry of the disease into the herd is the introduction of new animals into the herd. In this case report it was observed that the farm have had a history of CLA even though the farm had been depopulate, the use of infective biosecurity measures might have been the cause of reinfection of the farm.

Other measures aimed at reducing the impact of the disease in order to reduce the associated losses due to the occurrence of the disease is involves effective control of insects and disinfecting the umbilical cord of the neonates and skin abrasions with 10% iodine (de Sá Guimarães et al., 2011). Measures aimed at reducing environmental risk such as the use of smooth wires to fence pens, proper and frequent disinfection of the ear tagging and shearing instruments should be encouraged (Abdullah et al., 2013). Furthermore, since majority of the farmers are not aware of the implication of the disease, it is important to help educate the animal owners and farm personnel on the economic importance of the disease and be encouraged to report any case of CLA to the veterinarians. In addition, information about the zoonotic potentials of the organism should be made available to farmers and people who live around the farm environment or are involved directly in taking care of the animals. Strict adherence to this control measures will greatly help in reducing the outbreak of CLA.

This clinical case showed the importance of effective implementation of vaccination strategies and other control measures in the control and prevention of CLA in small ruminants and its zoonotic implications in humans.

The authors wishes to appreciate the management and staff of University Veterinary Hospital, Universiti Putra Malaysia (UPM) for their cooperation.

None to declare.

All authors contributed equally and approved the final manuscript.