CDC expert updates Kenya on Avian Influenza

Kenyan CDC expert Dr Kariuki Njenga tells of Kenya's preparedness for bird flu. "The best way to manage the threat is to control the disease at its source – in birds."

Dr Kariuki Njenga, a Kenyan expert working with the International Emerging Infections Programme in the Kenya office of the US Center for Diseases Control (CDC), delivered a seminar on avian influenza to staff of the International Livestock Research Institute (ILRI) at their Nairobi headquarters on Thursday, 25 November 2005.

Dr Njenga said that the influenza viruses are some of the most intriguing and elusive in the world. Special characteristics of the highly pathogenic avian flu virus strain known as H5N1 increase the likelihood that there will be increased emergence of chimeric (new) viruses, one or more of which could cross over to humans and be transmitted from human to human and cause a flu pandemic.

Increased associations between animals and people, Dr Njenga said, especially in Southeast Asia, is providing a conduit for the avian influenza virus to come into contact with people as they handle dead or dying infected birds. Most of the 122 human cases of the disease, with 62 deaths, so far reported to the World Health Organization have occurred on backyard farms where poultry are kept.

‘Our main concern right now in Kenya and other countries in Africa along the migratory bird flyways’, said Dr Njenga, ‘are backyard chicken farmers’. More than three-quarters of Kenyans are rural farmers and it is estimated that more than 90 percent of them keep chickens. The fear is that wild birds infected with the deadly H5N1 virus strain now migrating to Kenya for the European winter might come in contact with domestic water birds, such as ducks, which then might contact free-scavenging chickens kept by poor rural people, and so the virus could be passed from birds to people. If this happens, the country would have to act within 21 days to contain the infection to prevent the outbreak spreading wide.

ILRI and CDC staff are part of a national task force that has been assembled in Kenya to deal with bird flu. This task force is providing early warning of bird die-offs and strengthening surveillance nationwide, developing a communications network and stock-piling anti-virals so that these are on handle to contain any outbreak. There is no effective vaccine to prevent a pandemic caused by the H5N1 flu strain.

The task force is instructing Kenyans to note any sick or dead birds. They should report these to veterinary or government authorities or they may collect dead birds in plastic bags, using plastic bags to protect their hands as they do so, and take them to their local veterinary officer.

ILRI and WHO agree to work together more closely for better human health

ILRI and WHO sign a memorandum of understanding to promote human health and the control of zoonotic diseases.

In September 2005, a memorandum of understanding was signed between the International Livestock Research Institute (ILRI) and the World Health Organization (WHO). The agreement was signed by executives from both organizations in recognition of the need to better understand the links between livestock keeping and the health and general well-being of poor people in poor countries.

This agreement makes possible more effective collaboration and coordination between ILRI and WHO on human health and the control of diseases transmitted between animals and people (zoonoses) and associated with livestock and livestock products.

The agreement facilitates collective action on issues of concern to both organizations. WHO is involved in the surveillance and response to health problems of its member countries while ILRI obtains evidence on the impact of zoonotic diseases on the health and livelihood of poor people.

“We want to make sure that our research activities are integrated with the surveillance and control needs at the international level. Otherwise, why do research if there is no demand for it?", says Dr. Lee Willingham, a research scientist on parasitic zoonoses at ILRI.

The general objective of this agreement is to maximize synergies in the work of the two organizations in the following areas.

  1. Exchange of information on technical areas of common interest to achieve complementarity and coordination between relevant activities and programmes.
  2. Development of joint activities to address issues of mutual interest that are designed to foster and promote  a greater capacity for research and technology application in developing countries and to facilitate the building and consolidation of global partnerships in the scientific community. The joint projects will be supported through special supplemental project proposals and may involve secondment of staff from one organization to the other or other appropriate administrative arrangements.
  3. Promotion of synergies and elaboration of collaborative programs in areas where the two organizations can best employ their comparative advantages.

Epilepsy, brain cysts and tapeworms

Ten pigs went to market, some pigs stayed at home, all pigs ate human faeces… and so a deadly tale begins. Poor sanitation, poor hygiene practices, poor pig husbandry and poor meat inspection all fuel a vicious cycle that is destroying lives and livelihoods in many developing countries. A potentially deadly parasite, Taenia solium, known as the pork tapeworm, is being transmitted from pigs to people, people to pigs and from people to people. The disease Cysticercosis has been dubbed one of the neglected diseases of neglected populations. It is considered by the World Health Organization to be one of the few potentially eradicable diseases, yet it is now an emerging disease of eastern and southern Africa. Awareness and training activities are being organised in eastern and southern Africa to help combat the parasite that causes intestinal taeniasis in humans, cysticercosis in pigs and humans, and the potentially deadly human disease neurocysticercosis, which is the formation of (T. solium) cysts in the brain. Neurocysticercosis affects millions of people in Asia, Latin America and Africa. It is rarely found in industrialized countries or in countries where pork is not consumed for religious or cultural reasons. However, even in these countries more cases are being seen due to immigration, increased travel and importation of domestic workers from endemic countries. It is a disease associated with poverty and underdevelopment, and is endemic in many developing countries where raising pigs and eating pork are popular. Neurocysticercosis infection may remain non-symptomatic for years before manifesting as seizures, severe headaches or other neurological problems. It is also a major cause of acquired epilepsy in developing countries. It affects agility, concentration and in severe cases can result in death. The true extent of the problem is not known because tapeworm carriers often do not know that they are carrying the parasite. It can lie in the human gut for years without causing any symptoms. Major advances are being made in the diagnosis and treatment of people and pigs infected with pork tapeworm, but these diagnostic tools and medical treatments are not yet widely available in many endemic countries. A vaccine to prevent pigs from contracting the disease is also being developed. How it is spread Since the mid 1990s, more and more people in rural areas in eastern and southern Africa are keeping pigs, fuelled in part by a significant increase in the consumption of pork in both rural and urban areas. To poor smallholders in these regions, pigs represent a new opportunity in livestock keeping worth exploiting. In Africa cattle are highly prized, but they can be problematic – protecting them from disease and theft requires constant vigilance and sometimes round-the-clock surveillance. Pigs, however, are comparatively easy to manage, and are therefore becoming increasingly popular and important, especially in rural smallholder communities. Pigs, like so many livestock, can serve as a 'mobile bank', with one adult pig fetching upwards of US$100 at markets in this region. Many farmers will keep between one to three pigs and sell an adult pig at the beginning of the school year to provide for school fees. However, the increasing number of pigs being kept in eastern and southern Africa is raising its own set of problems, with a vicious cycle of infection and reinfection. This is not just a problem for rural areas, where most pigs are kept, but it is also a problem for urban areas where infected pork can be consumed, and where human carriers of the parasite can infect other people. Most worrying is the fact that people do not have to eat pork or keep pigs to become infected with cysticercosis. They can be exposed to the eggs from a human tapeworm carrier. Disease and poverty go hand in hand. Poor sanitation and poor hygiene practices all increase the risk of contracting diseases. In many developing countries, particularly in rural areas, human waste is generally disposed off in a pit or out in the fields, or in some cases it is simply thrown into the garden. In many poor areas, livestock keeping is rudimentary and pigs, like many livestock, wander about freely. When the livestock keepers and family members go out to the fields to defecate, their pigs will follow. Pigs like to eat human faeces and will trail out to where people have defecated to eat the stool. If these people are carriers of the tapeworm they will produce thousands of highly contagious eggs in their stool. These eggs are hardy and may survive more than eight months in the environment, particularly in tropical conditions; the climate in Africa is ideal for the parasite to thrive. This presents a health hazard not only for pigs, but also for people. If pigs ingest the eggs, they develop into the immature larval form of the parasite (cysticercosis) that can result in the formation of hundreds to thousands of cysts in the muscles of the animal. In areas where meat inspection and control is lacking, infected pigs are often slaughtered and the pork sold for human consumption. Eating infected raw or undercooked pork can cause people to become infected with the adult tapeworm form of the parasite (taeniasis). The parasite will remain in their gut, but eggs of the tapeworm will be expelled through their faeces. This does not, however, cause neurocysticercosis, which requires transfer of the contagious eggs from the infected person’s faeces to the same or another person. If humans come into contact with infected human stool and accidentally ingest the eggs, the eggs develop into the larval form of the tapeworm, which targets the muscles, the eyes and most commonly the brain (neurocysticercosis), manifesting as cysts. This may occur through direct contact with a tapeworm carrier’s infested stool, by putting contaminated fingers in the mouth, or through ingestion of water or foods that have become contaminated with the infected faeces. Awareness and control Pig traders have become aware of the heightened problem of cysticercosis in pigs. Many were finding that when the pigs they had purchased were slaughtered and inspected, they had cysts and were therefore condemned. As a result, some pig traders have become extremely vigilant and now routinely carry out checks on pigs before purchase. Examining the underside of the pig’s tongue is a quick, easy and cheap way of checking for positive signs of infection, but may only detect about 50% of the pigs infected. Visual observation of the pork meat can also be used to determine the presence or absence of the parasite. However, in areas where livestock and meat inspection are not so vigilant, infected pigs can be slaughtered and sold for human consumption. The increasing consumption of pork in urban areas means that infected pigs can be transported into densely populated areas, where the infected pork finds its way into human diets. These unwitting consumers then become carriers of the parasite. In poor rural communities where people are carriers of the intestinal tapeworm and pigs are allowed to roam and consume human faeces, it is likely that pigs will become infected with the parasite. For these poor livestock keepers, their losses are threefold – they lose the income they expected to receive from the sale of their pigs; they and their families lose a valuable protein source when the pig carcasses are condemned, thus increasing the likelihood of family malnutrition; and their own health and productivity are at risk from cysticercosis infection. There is also the risk of tapeworm carriers transmitting the parasite to other people. Prevention Cysticercosis can be prevented by interrupting the life cycle of the parasite at one or more points. Good pig husbandry, including preventing pigs access to human faeces, is one way to break the cycle. Total confinement of pigs is a possibility but only sustainable if integrated with other management practices such as housing and feeding with locally available materials and feedstuffs. Strict meat inspec

tion and control also helps to break the cycle, preventing infected meat from being consumed by people. Good hygiene practices and thorough cooking of pork can prevent people getting infected, or reinfecting themselves and/or infecting others. These measures require education and training of all involved, including pig keepers and their families, pig traders, meat sellers, and the general public – whether they eat pork or not.