1. Examining Trypanosomiasis in Moyo, Uganda: A pilot study
Kaylan Utterback, BA, Katherine Fogelberg, DVM, PhD, Thomas Graham, DVM,
MPVM, PhD
ABSTRACT
INTRODUCTION/BACKGROUND
METHODS
CONCLUSION
A special thanks to:
The people of Moyo
Dr. Thomas Graham, DVM, MVPM, PhD
Dr. Katherine Fogelberg, DVM, Phd
Alex Baker
Kellie Curtis
Dr. Stanley, DVM
Dr. Vincent, DVM
Robert Howard
RESULTS
DISCUSSION
A team comprised of veterinarians and public
health students, from the U.S. and Uganda, worked
with Veterinarians Without Borders (VWB)
collecting animal and human samples in Moyo,
Uganda during the summer of 2016. The purpose
of the study was to promote One Health initiatives-
interdisciplinary approaches to humans, animals,
and the environment. The objectives of the project
were to provide baseline samples of T. b.
gambiense, also known as trypanosomiasis and
African Sleeping Sickness, tuberculosis (TB); and
brucellosis, in both livestock and the households
that own them, work with local veterinarians to
promote active surveillance, and improve
knowledge, treatment, and prevention of these
diseases. This project will focus specifically on
trypanosomiasis and its relationship between
humans and livestock.
Trypanosomiasis (tryps) is a neglected disease,
disproportionately affecting the bottom 1.4 billion
people of the world living in extreme poverty1
.
Development for diagnosis and treatment are
equally inhibited by this neglect2
.Trypanosomiasis
is a vector borne parasitic disease that is
transmitted exclusively through the tsetse fly3,4
. In
the first stage, patients experience fever,
headaches, joint pains and itching, similar to
symptoms of malaria. In the second stage, the
parasites cross the blood-brain barrier into the
central nervous system causing behavioral
changes, confusion, sensory disturbances and
poor coordination. Sleep cycle disturbances, which
gives the disease its name, is an important feature.
Without treatment, sleeping sickness is considered
fatal4.
Animals can also be infected, with cattle and
other livestock acting as reservoirs of the disease.
In Moyo, this was thought to be a contributing
factor to the prevalence of tryps in the area.
Additionally, most homes are pastoral, that is they
graze cattle and goats and keep them in close
proximity to their homes. Men are responsible for
handling cattle while women are responsible for
handling goats, meaning care for livestock is
separated by sex. It is hypothesized that this
difference is also seen in disease prevalence,
where men have higher rates of trypanosomiasis
compared to women due to their prolonged
exposure to cattle.
Field collection of blood in individual animals and
humans were in large enough quantities to allow
for separation into whole blood and serum
samples, which were both needed for testing
various diseases. For field lab processing of
trypanosomes, the process is as follows:
•Thin and thick smears
•Capillary tubes
•Capillary tube readings for hematocrit
•Examine Capillary tube in microscope for
Trypanosomes
Human samples were collected by a local
phlebotomist, and processed by local lab
technicians in the field lab, as students were only
allowed to handle animal samples.
For human samples, the lab used Card
agglutination tests for trypanosomiasis (CATT),
which are sensitive, inexpensive, and quick2
.
This is a field test used to determine the
presence of T. b. gambiense, the chronic variant
of the disease, and is used in congruence with
microscopic testing to determine the presence of
trypanosomes in human blood.
It was found that 127 (n=807) participants tested
positive from the CATT and 98 (n=1514) cattle
tested positive via microscopic examinations.
Out of these persons, nine households had
parallel positive human and positive cattle tests.
Sex of participants in nine households where
humans and their livestock both test positive for
Trypanosomiasis
Positive CATT
n =127
Positive
Livestock
n = 98*
Male 6 5
Female 3 4
Total 9 9
* Were tested using a microscope
Kennedy, (2012) Clinical features, diagnosis, and treatment of human African
trypanosomiasis (sleeping sickness)
Despite testing pigs, cattle, goats, and sheep,
cattle were the only livestock to test positive for
the presence of trypanosomes, which could
possibly be linked to their preferred consumption
of tsetse flies5
. There was little variation in sex
when men are presumed to be at a higher
exposure from being in contact with the only
animal to test positive. Households where both
animals and humans that tested positive were
not significant enough to make any conclusions
about relationships that exist between animals
serving as a reservoir for contracting or
spreading human disease. Additionally, false
negatives can occur due to trypanosomes
essentially hiding in the blood. A small
percentage of this parasite evades detection of
antibodies, allowing it to proliferate until the new
surface antigen coat is recognized by a new
generation of specific antibodies, mainly
immunoglobulin M (IgM) 2
.
This may explain why results for households
where animal and humans both had the
disease were not as prevalent as expected.
Potential weaknesses in this project include to
human error during when collection, analysis,
storage, and data interpretation. For example,
cattle samples were microscopically viewed
and the unstained capillary tube samples were
difficult to read. Additionally, field conditions
made it hard to test live trypanosome samples
within the 45 minute time frame during which
the sample is taken, processed in the lab, and
viewed under the microscope.
The team is still awaiting the results from
Makere University where thin and thick smear
microscopic slides were sent for further testing.
It will be interesting to see if the findings shift
once experts with good equipment are able to
confirm our findings.
Developing nations disproportionally experience
neglected tropical diseases. These diseases
often result in chronic conditions, loss of
economic productivity, childhood disabilities,
and premature deaths that continue to
propagate their impoverished state.
Trypanosomiasis is just one of the many
diseases on the African continent that impacts
millions of people daily. The World Health
Organization (WHO) reports that 100 new
cases per year of African Sleeping Sickness
come out of Uganda. According to this project,
127 cases were found in the Moyo district
alone, indicating a potential gross under-
reporting for this disease. In Uganda, future
efforts to control the tsetse fly, provide
continued surveillance, and accessible
treatment for the disease are necessary for
control, reduction, or elimination of
trypanosomiasis.References:
1. Hotez, P. (2011). Neglected tropical diseases and their neglected infections of poverty: overview of their common features,
global disease burden and distribution, new control tools, and prospects for disease eliminations. The Causes and
Impacts of Neglected and Zoonotic Diseases: Opportunities for Integrated Intervention Strategies, Washington D.C.:
The National Academic Press.
2. Chappuis, F., Loutan, L., Simarro, P., Lejon, V., Büscher, P. (2005). Options for Field Diagnosis of Human African Trypanosomiasis.
Clinical Microbiology Reviews, vol. 18 no. 1 133-146, doi: 10.1128/CMR.18.1.133-146.2005
3. Center for Disease Control and Prevention (CDC). 2015. Parasites - African Trypanosomiasis (also known as Sleeping Sickness):
Control and Prevention. Retrieved from: https://www.cdc.gov/parasites/sleepingsickness/prevent.html
4. World Health Organization (WHO). 2016. Fact Sheet: Trypanosomiasis, human African (sleeping sickness). Retrieved from:
http://www.who.int/mediacentre/factsheets/fs259/en/
5. The Center for Food Security and Public Health. (2009). African Animal Trypanosomiasis. Retrieved from:
http://www.cfsph.iastate.edu/Factsheets/pdfs/trypanosomiasis_african.pdf