Monday, February 12, 2007

What I did in Uganda

Zoonotic Disease Survey in Karamoja, Uganda

Background

In January-February 2007, a team of volunteers from the Kansas State University (KSU) branch of Christian Veterinary Missions (CVM) traveled to Karamoja, Uganda at the invitation of Dr. Val Shean of CVM. The trip was funded by private donations and the members.

The purpose of this project was to initiate a zoonotic disease survey. Zoonotic diseases, while important in high income countries (HIC), become critical in low income countries (LIC). In LIC’s, direct contact with livestock is more common and basic hygiene is less common (and less possible) than in HIC’s. In HIC’s, zoonotic disease surveys and control are often in the hands of the government, as, for example, in the USDA’s brucellosis control programs. In LIC’s, however, the government is unable or unwilling to pay for such expensive programs; the livestock production systems are also too decentralized for such a top-down approach. This leaves the livestock keepers of these countries to rely on private laboratories (which are too costly for subsistence farmers) or development programs for identification of zoonotic diseases in their animals. It is such a development program, Cooperative Livestock Integration and Development Enterprise (CLIDE), with which this survey is being performed, in collaboration with the Italian Cooperation and Development program (CD).

Karamoja is a semi-arid region in the northeast area of Uganda, in East Africa. It is primarily inhabited by the Karimojong tribe, semi-nomadic livestock herders. This survey is currently focused on the Moroto district, which is a central area of about 7000 square kilometers, only 48% of which is arable. 90% of the population relies on agriculture for a livelihood. According to a 1995 estimate, there are over 400,000 head of cattle and over 600,000 goats in Moroto district.

The zoonotic risk factors of the region fall into management and cultural categories. Management issues are generally related to livestock mixing and resource availability. Due to the limited water supply in the region, these livestock congregate regularly at the few water pumps or reservoirs, facilitating the spread of infectious diseases. In addition, due to inter-tribal raiding, cattle are collected into corrals within the compounds (manyattas) overnight to protect them. As the people live in huts surrounding these corrals, aerosolized disease can spread easily from cattle to people. In the dry season, the manure pack of the corrals is also aerosolized and carried in the strong winds, spreading throughout the manyatta. The lack of readily-accessible water also makes hygeine difficult; washing of hands after handling animals or before cooking meals is rare. Disease spread between cattle and people is then potentiated, as is disease spread between people. Dogs are also managed in such a way as to increase risk of some zoonotic diseases; due to a fear of rabies, dogs are rarely handled and thus almost never vaccinated or treated for disease.

Cultural risk factors for zoonotic disease are related to food safety concerns. The Karimojong rely on livestock for their main protein sources: blood and milk. Blood is collected from live animals and at slaughter to be drunk raw or cooked, primarily the former. Milk is most often drunk raw or made into sour butter, or ghee. Cow’s milk is used by adults, while goat’s milk is only drunk by the children. The boys responsible for following the herds to pasture will milk the goats into their hands and drink the milk immediately. This means they are exposed to pathogens in these food products.

Health care is in short supply; in the Moroto district, only 24% of the population has access to health care. When official diagnoses can be made, treatment is often too expensive unless highly subsidized.

Diseases Surveyed

The Matany Hospital, one of the privately-run, donor-funded health facilities in the Moroto district, provides subsidized treatments, treating over 100 cases of tuberculosis (TB) and a fair number of cases of brucellosis each month. Due to the apparent prevalence of these zoonotic diseases in the human population of the region, brucellosis and TB in cattle were chosen as the primary focus of the first survey. In addition, Echinococcus granulosus is a common finding in the small ruminants of the region at slaughter; as this is a zoonotic disease with a life cycle passing through the dog, a canine element was added to the survey.

Brucellosis is a bacterial disease transmitted to humans primarily through unpasteurized dairy products, although manure and saliva are also possible sources of disease. It produces recurrent fevers, mimicking malaria, swollen joints, and nervousness or irritability. The primary symptom in cattle is abortion. The disease is most often spread between cattle by contact with the aborted fetus and the placenta from those abortions. It may also be spread sexually; infected cows will infect a bull during coitus, which can then infect other cows in a similar manner.

TB is a mycobacterial disease also transmitted to humans through unpasteurized dairy products, although human to human transmission of the human-specific Mycobacterium tuberculosis is more common in most of the world than the zoonotic Mycobacterium bovis. Feces, saliva, and aerosolized sputum (from coughing) are all sources of disease, for people and for animals. In people and animals, the symptoms of TB are fever and inappetence, leading to a thin appearance.

Hydatid disease, caused by the tapeworm Echinococcus granulosus, generally exists in a lifecycle between dogs and small ruminants. The adult lives in the intestine of the dog, passing eggs through the feces. The small ruminant then ingests those eggs, which hatch into larvae. The larvae encyst themselves in the viscera; when those cysts are ingested by the dog, the life cycle begins anew. Humans ingesting the eggs may become infected and develop cysts in the liver, lungs, and brain, requiring surgical removal.

Procedures

The team from KSU travelled to Karamoja in order to bring testing supplies and train a local team of animal health workers and veterinarians in the skills necessary to survey the cattle of the Moroto district for brucellosis and TB. Testing supplies sufficient for 1000 head of cattle were supplied to the Karamoja Diagnostic Laboratory, a part of CD. This sample size will allow determination of the true prevalence of disease with 95% confidence intervals of +/- 2%.

Testing procedure within a manyatta was based on clinical signs and relative risk; owners were requested to identify breeding bulls, older cows, and any animals that have aborted or experienced prolonged coughing recently. For each animal, the following information was collected: name, age, sex, color, clinical history, current temperature, and treatment history. Blood was drawn from a tail vein into a red-top tube and tuberculin was injected intradermally into the caudal tail fold. The animal was then given an ear tag and a subcutaneous injection of Ivermectin, as a thanks to the owner for allowing testing. After 72 hours, the caudal tail fold was examined to determine TB reactivity. The blood was taken on ice to the Karamoja Diagnostic Laboratory, where it was centrifuged to produce serum. The serum was then used in the standard Rose Bengal card test, as provided by the USDA-NVLS Brucellosis laboratory.

Results

By the end of the week available for testing, 56 animals had been tested for brucellosis and 26 had been tested for TB. Due to the time constraints of reading TB tests within 72 hours, 30 cattle were tested for brucellosis but not TB; those animals will be TB-tested at a later date.

The Rose Bengal test showed 9 positive reactors in the 56 tested, including both bulls and cows. The director of the laboratory and the laboratory technician were trained in the performance and reading of the test.

The TB test produced one reactor, which will later be confirmed via culture of the sputum and comparative cervical test. Two field veterinarians were trained in the performance and reading of the test.


In the 9 canine fecals performed, only Ancylostomma eggs were observed. One unidentified adult tapeworm was seen; however, follow-up was not possible.

Conclusion

The zoonotic disease survey as carried out so far has established the presence of both brucellosis and TB in the cattle of the Karimojong. It is important to continue this study and establish both prevalence data and risk factor analysis; with that data, a control plan can be established to improve public health in the region. A recent meeting with the district veterinary officers of the four districts in Karamoja and the regional medical centers established the interest and support of the local veterinary and human medical community. It is to be hoped that the survey may be expanded to include other zoonotic diseases and other districts.

Other posts on this topic:I'm back!, More teasers, Today's photo theme: Mother and child, Today's photo theme: cows (of course!), Today's photo theme: the men, Today's photo theme: the markets, Today's photo theme: pathologies!, Today's photo theme: plant life, Today's photo theme: sunrise, sunset

And, of course, my flickr site.

3 comments:

Valerie E. Ragan DVM said...

Becky,

I read your post on the Uganda surveillance with interest, and applaud your effort to help define and ultimately improve zoonotic disease conditions in LICs.

I have previously served as USDA's National Brucellosis Epidemiologist, and currently work to train veterinarians internationally on brucellosis control and eradication through my company AgWorks Solutions. I would like to comment on an error in your post related to brucellosis transmission. In cattle, brucellosis is primarily transmitted at the time of abortion or an infective calving, by ingestion (via licking, sniffing etc) of the highly infectious reproductive materials such as placentas and reproductive fluids. Brucellosis, while being a reproductive disease, is not generally transmitted sexually in cattle. It is transmitted sexually in swine and canines (B.suis and B. canis respectively), but not in cattle (B. abortus) with normal breeding. (Although it can be transmitted by artificial insemination in cattle). This distinction is very important when it comes to management of the disease for control or eradication purposes. It is critically important to properly manage animals at calving, and livestock owners need to be aware of the importance of calving management in order to minimize transmission.

I hope this clarification is useful to you. Best of luck to you on your efforts.

Valerie E. Ragan DVM

Valerie E. Ragan DVM said...

Becky,

An addition to my own comment! - In cattle in Africa, you are likely dealing with B. abortus AND/OR B. melitensis. We don't have B. melitensis in the U.S., but much of the world does.

Best of luck to you,

Valerie E. Ragan DVM

Jason Kevin said...

Am not fully convinced of your statement that brucellosis is primarily transmitted at the time of abortion or an infective calving, by ingestion and that IT is not generally transmitted sexually in cattle.