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Condition Monitoring & Disease Surveillance

CONDITION MONITORING AND DISEASE SURVEILLANCE

 

Cleve Cheney

 

The wildlife industry is worth billions of rands. Imagine the catastrophic losses that could result if a disease like rinderpest suddenly made an unexpected appearance once again. It could potentially wipe out the wildlife industry and destroy the livelihood of thousands of people. It bears thinking about.

 

The value of wildlife has increased almost exponentially over the past two decades. One need only peruse a list of game auction prices over the last 20 years or so to see how the value of wildlife has skyrocketed. The cost of some species far surpasses that of domestic livestock. Such valuable commodities deserve proper care and attention.

 

Wildlife managers should constantly monitor the condition of wildlife, as it is an indicator of the well-being of animals. It is quite normal for condition to drop during the winter months (Photo 1) when resources become scarcer, and to improve in the summer months when browse and grazing is optimum. Alarm bells should begin to ring when condition does not improve when forage improves, or when condition drops when forage conditions are good. Chronic poor condition is also a sign that something is wrong. If a decline in condition is spotted early enough, steps can be taken to correct whatever is causing the decline. Poor condition can be indicative of the following:

  • not enough food (a decline in vegetation condition) or food of poor quality
  • not enough water or water of poor quality
  • heavy parasite loads
  • too much competition for available resources (i.e. overstocking)
  • disease conditions

 

How to monitor condition

The best way to monitor condition is to observe wildlife at close range or to use optical aids to bring you up close enough to conduct an overall appraisal of individuals. Vehicle or horse patrols (where they are a workable option) are a good choice, as most wildlife will allow you to approach quite close using these modes of transport – close enough to inspect individuals. Foot patrols are generally not conducive to condition monitoring, as most wildlife will not allow you to approach close enough on foot to carry out a visual scan of individual animals. A very good place to carry out surveillance is from hides at waterholes (see Photo 2). Animals can be clearly observed from a concealed position and they generally spread out so that individuals can be scanned. The one disadvantage is that animals that do not frequent waterholes will be missed. What should one be on the lookout for which could indicate that an animal is sick or in poor condition?

 

  • Staring, dull or patchy coat

The coats of animals in good condition are usually sleek and shiny (see Photo 3). When the coat becomes dull or patchy due to hair falling out, stands up straight as opposed to lying flat or changes colour, it is an indication that something is wrong. Hair loss is a symptom of for example mange (see Photos 4 and 5), or a result of heavy parasite infestation. Change in coat colour can be an indication of mineral imbalances.

 

  • Loss of muscle mass and skeletal structures becoming prominent

A sure indication of poor condition is when animals become thin and skeletal structures such as ribs, hipbones and spine become prominent. When there is a loss of muscle mass (weight loss), the rounded parts of an animal such as the rump and shoulder take on a distinctly angular or concave shape (see Photo 5). There can be many causes for loss of weight such as not enough food or food of poor quality and disease conditions such as bovine tuberculosis or foot-and-mouth disease. In predators, emaciation often follows when a major bone is broken in the legs, shoulder, hip joint, etc, rendering it very difficult or almost impossible to catch prey.

 

  • Obvious abnormalities such as growths, warts, wounds or external injuries

When observing wildlife with the purpose of condition monitoring and disease surveillance always be on the lookout for abnormalities. Growths may be caused by infected wounds, cancers, or brucellosis for example (see Photo 6). Warts are caused by viruses and are usually self-limiting (Photo 7). External injuries may be observed, which can result from fighting, running into fences or objects, snares (Photo 8), predation or being wounded by firearms.

 

  • Weakness, limping or stumbling

When an animal is weakened due to a drop in condition or injury, the normal healthy gait may be replaced by a slow, unsteady one. The animal may be reluctant to run away when approached and walk with the head held low. If a limb has been injured the animal may drag or favour the injured limb and will limp.

 

  • Large number of visible ectoparasites

There seems to be a direct correlation between parasite loads and level of condition. When condition declines the endo- and ectoparasite loads increase. Obviously one cannot see internal parasites when observing animals from the outside but ectoparasites such as ticks are visible. Heavy infestations are often localised in the axilla (armpits), between the hind legs and under the tail (Photo 9). In some species such as eland, heavy tick infestation is sometimes observed around the base of the ears. In severe cases, this can eventually cause the ears to drop off. If animals are observed with heavy tick and other parasite loads, it is a definite indication that the animal is in poor condition and it would be advisable to establish the underlying cause.

 

  • Strange or abnormal behaviour

A wildlife manager gets to know his animals and to recognise normal behaviour patterns. When abnormal behaviour patterns begin to manifest it should arouse suspicion. Some types of abnormal behaviour patterns which may indicate disease or injury are loss of fear of humans (possibly rabies), chewing objects such as old bones or eating soil (could be indicative of mineral deficiencies), biting, chewing or nipping at body parts, continual scratching, overt aggression, changing from being nocturnal to diurnal, etc.

 

  • Herd animals walking alone

Gregarious animals such as baboons, vervets, elephant, buffalo, impala, wildebeest and zebra will stick together in herds, especially the females. Males form bachelor groups in some species and rams or bulls may become solitary, but the females of herd animals are usually found in association with individuals of their own species, and to see one walking alone would also warrant a closer inspection. Females of some species may break away from the herd to give birth during lambing or calving seasons but will rejoin the herd as soon as the calf or lamb has been hidden or is strong enough to accompany the mother.

 

  • Finding carcasses

Finding carcasses – especially ones that have not been killed by predators and have died from some other cause – requires further investigation to try and establish the cause of death (Photo 10). A thorough investigation of the site should be carried out as well as an examination of the animal. The wildlife manager should acquaint himself of the major symptoms of different wildlife diseases as this will influence the actions that should be taken. If for example symptoms indicate that the animal may have died of anthrax (animal still in good condition, tarry discharge from the anus, mouth and nose, signs of struggling prior to death, etc) the carcass should not be opened or handled. A blood smear should be taken and the carcass should be burned on the spot. If the cause of death appears to have been caused by something other than anthrax a post-mortem may be carried out during which small sections of all the internal organs should be collected and stored in a solution of 10 per cent formalin. If the wildlife manager does not know how to conduct a post-mortem, the local vet should be called in to carry out an examination.

 

What actions to take

The wildlife manager can take a number of steps to prevent disease in his wildlife populations and there is a protocol to follow when certain diseases or conditions begin to manifest themselves.

 

  • Identify wildlife diseases

Know what type of wildlife diseases do or can occur in your area and how to recognise their symptoms

  • Conduct vaccination and immunisation programs to prevent diseases

The wildlife manager should consult with a local vet to find out what wildlife diseases occur in a given area and what vaccines are available to administer to valuable animals to prevent them from contracting these diseases. The cost of vaccines is miniscule compared to the value of some animals. Some costs may be incurred when conducting an immunisation programme (e.g. cost of vaccines, immunisation darts, helicopter flying time, etc) but is well worth the expense.

 

  • Conduct routine deworming and external (ecto)parasite control

By using automatic applicators (such as the Duncan apparatus) and by adding ascaricides (worm control preparations) to drinking water a measure of control can be effected to limit internal and external parasites.

 

  • In suitable habitat make use of a burning programme to reduce parasite loads

Burning too infrequently may result in an increase in external parasites such as ticks, lice and mites. Occasional hot fires help to reduce the number of these parasites. Whereas fire is a useful management tool in savanna and grassland systems, some habitat types such as fynbos cannot tolerate frequent fires and burning should be done with caution.

 

  • Stay within the area’s carrying capacity (stocking rate)

Overstocking can lead to fierce competition for food and water, which may lead to fighting, which in turn may result in injuries or deaths. Overstocking may also result in damage to the habitat, which will reduce carrying capacity. If a drop in general condition is attributed to overstocking the obvious answer is to reduce the number of animals by either live capture and sale, capture and relocation, culling or hunting. The reduced stocking rate will give damaged habitat a chance to recover and will reduce competition for resources. When animal population densities become too high it can lead to the quicker spread of diseases and higher parasite loads.

 

  • Supplemental feeding

At certain times of the year when food supply declines or is of poorer quality it may be advisable to supply supplemental food and mineral licks to help animals get through the lean months of the year and maintain reasonably good condition. Animals in poor condition have lower immunity and are more prone to becoming sick and picking up parasites.

 

  • Report diseases to relevant authorities

Certain diseases must, by law, be reported to a state vet, police or magistrate when an outbreak occurs. Examples include anthrax, Rift Valley fever, foot-and-mouth disease, rabies, bovine TB and swine fever. The authorities will then take the necessary steps to isolate infected animals, establish the mode of transmission and prevent further spread of the sickness.

 

  • Combat outbreaks aggressively

Early detection of disease outbreaks is critical to successful containment. As soon as a disease outbreak is suspected, get expert advice on how to limit its spread.

 

  • Isolation and prevention of spreading

Attempt, as far as possible, to identify and isolate affected animals to prevent spread of a disease. Coughing can spread disease by droplet infection (e.g. bovine TB), mutual grooming can spread foot-and-mouth disease, and drinking from the same water supplies are just some examples of modes of transmission whereby a contaminated or sick animal can spread disease from one individual to another. Placing suspect animals or animals to be introduced onto a reserve for a quarantine period is strongly advised. Tests can be conducted to determine if the animals are ‘clean’ or not before releasing them into the reserve. In some cases complete burning of contaminated carcasses will be required as scavengers such as vultures, jackal, etc can eat from infected carcasses and themselves become infected with the disease or help to spread it.

 

  • Insect and invertebrate control

Insects and some other invertebrates are also vectors for the transmission of sicknesses. Control of flies, tsetse flies, fleas, mites and ticks can go a long way to prevent diseases in valuable wildlife populations.

 

  • Water monitoring

Test the quality of a reserve’s water sources on a regular basis for pathogenic organisms, pesticide and herbicide levels, and toxins released by algae.

 

Disease and condition surveillance should rank high on a reserve’s list of priorities.

 


Figure 5 Lion in very poor condition

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 7 Warts are caused by viruses and are usually self-limiting.

 

 

 

 

Figure 8 External injuries may be observed, which can result from fighting, running into fences or objects, and snares.

 

 

 

 

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