06 Nov 2014

The prevalence of measles (cysticercosis bovis) is growing at an alarming rate from 10-12 per cent around 2006 to 18-20 per cent to date.

Measles is a zoonotic parasitic disease of worldwide distribution maintaining its life cycle as the tapeworm (taenia saginata) in the alimentary tract of humans, and as the measles (cystecercus bovis) in beef and it causes few or no clinical symptoms in the human host, but it results in loss of carcass quality in cattle.

In an interview, the director of veterinary services, Dr Letlhogile Modisa said the incidence of beef measles in the country stood at 18-20 per cent, which represents around P60 million in lost foreign earning in the lucrative European Union meat market.

Dr Modisa said released eggs(cycticerci) can survive in cattle anywhere from weeks to years and can present economic problems to the beef industry and carcasses containing few cysts must be frozen at negative 20 degrees Celsius for 14 days before the meat can be used for human consumption and if the cysts are present/ many the entire carcass is condemned.

He said in Botswana the treated carcasses is not exported and is only sold locally which is a loss to the Botswana Meat Commission as the amount of money invested in the whole process of slaughtering and preparing the meat are never met.

Responding to a question on what to look for in cattle, Dr Modisa said the bean-sized cysticerci are oval, grayish-white, fluid-filled bladder-like objects approximately 10mm long by five mm wide and can be seen with naked eyes between two to four weeks following infection as nodules on the muscle of cattle, particularly in the heart, diaphragm, tongue and masseter.

He said the cysts give the meat a measel-like appearance when they occur in large numbers and each cysts produces only one adult tapeworm when ingested by humans and said cattle of any age are susceptible to infection.

He said no clinical signs occur when only a few cysticerci are present; however, heavy infections may cause an inflammation of the heart muscle caused by infections such as viruses (myocarditis) and heart failure associated with developing cysts in the heart.

The director said as yet, there is no licensed drug available that kills all the cysticerci in muscle and appealed to farmers to always make sure that their grazing areas are free of the human waste as these cysticerci breed in there.

He said usage of sludge from sewage as fertilizers on pasture is a potential source of viable tapeworm eggs to grazing cattle and said cattle should not be allowed to graze on pasture contaminated with hum an sewage and stated that egg viability can range from 16 days in untreated sewage to 159 days on pasture and the eggs can remain viable in the soil for days to weeks.

Dr Modisa said other causes of outbreaks occur when cattle gain access to water contaminated with sewage effluents or the spread of taenia saginata eggs by birds that frequent sewage outlets or feed on effluent discharge and stressed that water used for livestock purposes or irrigating pasture should be free of fecal contamination.

He said in humans the adult tapeworm (strobili) develops in the small intestine of man as only final host and said humans are infected when they eat raw or rare beef containing cysticerci.

Dr Modisa said the adult tapeworm can reach a length of 3 to 12 meters and contain over 1000 segments (proglottids) each containing between 50 000 and 80 000 eggs and said although a single worm is usually found, multiple worms can be present and in many cases, patients become aware of the infection by noticing segments (proglottids) in their stools.

He said many infections are without symptoms, and the carrier may be unaware of their infection, (taenia saginata). Infection result in mild symptoms such as loss of appetite, nausea, abdominal discomfort, diarrhea and weight loss and said detached segments crawling from the anus can cause some discomfort.

Dr Modisa said worms can survive for up to 25 years in the intestine unless removed by medication and said drug therapy is usually very effective, but retreatment may be necessary.

He said they have an inter-ministerial committee comprising different stakeholders such as staff from ministries of health, local government and farmers committee’s representatives. ENDS