Some perspectives of dynamics of leishmaniasis infection in poor nations by

1
Some perspectives of dynamics of leishmaniasis
infection in poor nationsby

• J.Y.T. Mugisha Ibrahim M.ELmojtaba
• Biomathematics Group, Makerere University
• University of Khartoum, Faculty of Mathematical
  Sciences
• A paper presented at DIMACS Workshop on Economic
  epidemiology,
• Makerere University,
• 3 5 August, 2009

2
What is Leishmaniasis

• parasitic disease Transmitted by a bite of the
  infected female sand fly, that is usually
  infected with one species of Leishmania
• About 30 species of sand flies can become
  infected when taking a blood meal from a
  reserviour host.
• Most of the leshmaniasises are zoonotic
  (transmitted from to human from animals esp.
  dogs)
• The human becomes a sole reservoir if the
  transmission is anthroponotic

3
Forms of the disease

• Visceral leishmaniasis, (also known as kala-azar)
  the most severe form in which the parasites
  migrate to vital organs, and potentially fatal if
  un treated
• Cutaneous leishmaniasis, the most common form
  which causes a sore on the site of bite which
  heals in few months to a year leaving unpleasant
  scar
• Diffuse cutaneous leishmaniasis that produces
  wide spread skin lesions (similar to leprosy) and
  very difficult to treat, never heals
  spontaneously and tends to relapse after
  treatment
• Mucocutaneous leishmaniasis that starts with an
  ulcer which spreads causing tissue damage esp.
  nose, mouth
• There is also the Post-kala- azar dermal
  leishmaniasis (PKDL) that is an illness condition
  got after cutaneous (with depigmented eruptions
  mainly on the face, arms, feet, upper part of the
  trunk etc)

4
Symptoms-V Leishmaniasis

• In children
• Vomiting, Diarrhea, Fever, Cough
• In adults
• Fever for 2 weeks to 2 months, along with
  fatigue, Weakness, Night sweats, Weight loss etc

5
Symptoms-C Leishmaniasis

• Skin sores
• Skin ulcer
• Erosion of tissue on the mouth, tongue, gums,
  lips, nose and inner nose
• Swallowing difficulty
• Stuffy nose, runny nose, nosebleeds

6
The disease

• The disease begins as an erythematous papule at
  the site of the sand fly bite on exposed parts of
  the body. The papule increases in size and
  becomes a nodule. It eventually ulcerates and
  crusts over. The border is usually raised and
  distinct. There may be multiple lesions,
  especially when the patient has encountered a
  nest of sand flies.
• The ulcer is typically large but painless unless
  there is secondary bacterial or fungal infection

7
Disease

• The mucosal form usually occurs after an initial
  cutaneous infection and they usually begin in the
  nose or palate (WHO fact sheet, 2003).
• Lesions progress to destruction of mucosa and
  even cartilage. They result in scarring and
  disfigurement and can cause pulmonary aspiration
  and death.

8
Deformities

• Cutaneous leishmaniasis can become disseminated
  (diffuse cutaneous leishmaniasis), especially in
  immunosuppressed persons. This can result in
  deformities and disfiguring of the face
• This illness can go on for years. Patients with
  human immunodeficiency virus (HIV) infection are
  particularly susceptible.

9
Distribution

• Although cutaneous leishmaniasis can be traced
  back many hundreds of years, one of the first and
  most important clinical descriptions was made in
  1756 by Alexander Russell following an
  examination of a Turkish patient
• Mainly a disease of Developing world and rarely
  known in developed world
• Now endemic in 88 countries on five continents.
  Bangladesh, Brazil, India,, Nepal, Sudan, Peru,
  Saudi Arabia, Syria, Afghanistan, Iran (check WHO
  sheet for numbers)

10
CutaneousLeishmaniasisdistribution
11
Distribution examples cont
Distribution of cutaneous leishmaniasis causedby
L. major with a rodent reservoir
12
Distribution Cont

• Distribution of Leishmania species
  causingcutaneous Leishmaniasis in Central and
  South America

13
Public Health Concerns

• WHO estimated that the global prevalence of all
  forms of these diseases is 12 million cases and
  that the annual incidence is 1.5 - 2 million
  cases.
• Of human diseases caused by protozoan parasites,
  visceral leishmaniasis alone comes second in
  public health importance (after malaria) as
  measured by DALYs (Disability Adjusted Life
  Years) (Markle Makhoul (2004) ).

14
Public concerns

• Cutaneous leishmaniasis occurs throughout the
  Americas from Texas to Argentina, and in the
  Middle East and North Africa. The condition is
  diagnosed every year in travelers, immigrants,
  and military personnel. It is endemic in 88
  countries throughout Africa, Asia, Europe, and
  North and South America (Dedet and Pratlong,
  2003).
• There are an estimated 12 million cases
  worldwide, with 1.5 to 2 million new cases each
  year. Leishmaniasis is a disease associated with
  rural areas and poverty, but it has adapted to
  the urban environment as well.

15
Public Concerns

• As a disease very closely associated with
  poverty, leishmaniasis usually affects the
  poorest people of the poorest countries 72 of 88
  countries affected are developing and 13 of them
  are among the least developed. It is here where
  more than 80 of the population earns less than
  US2 per day (Davis et al 2003).

16
Control of Leishmaniasis

• No effective vaccine exists against the disease
  and no prophylactic drugs.
• Treatment is expensive and frequently followed by
  a relapse.
• Current means of control are aimed at the sand
  fly vectors
• No preventive vaccines or drugs (Reithinger,
  2007)

17
Control

• Vector control
• Insecticide spraying
• Genetic control
• Biological control
• Chemical control
• Are these manageable in poor countries?

18
Intervention targets

• Control of animal reservoirs
• Drugs
• Vaccine
• Personal protection
• Vaccine
• Repellents
• Early diagnosis and treatment

19
Exams and Tests

• Tests include-
• Biopsy of the spleen and culture
• Bone marrow biopsy and culture
• Direct agglutination assay
• Skin Biopsy
• Complete blood count
• Montenegro skin test

20
Possible complications

• Deadly infection due to immune system damage
• Disfiguration
• Hemorrhage (bleeding)
• Treatment Medicines called antimony containing
  compounds, Amphotericin B, Pentamidine often
  expensive
• Treatment cycle cost 30 - 120.
• In case of relapse, patient needs to be treated
  with far more toxic second line medicine 60-70
• Amphotericin B has no side effects but costs gt
  1500
• Plastic surgery unmanageable in developing
  countries
• Removal of spleen (splenestomy) may be needed on
  drug-resistant cases, this is very expensive
  surgical process in many cases these countries
  have not theatres to carry out this procedure

21
Poverty trap

• In some parts of Asia, a family in which there is
  a case of leishmaniasis is three times more
  likely to have sold its cow or rice field, than
  unaffected family plunging it into a vicious
  circle of disease-poverty-malnutrition-disease!

22
Need for a cost-effective control exits

• WHO report 2006 no well-defined cost-effective
  control exits. There is need to strengthen both
  active case detection and diagnostic capacity in
  rural health centres where most of the patients
  are usually treated
• Cost of medication and cost of admission to
  hospitals as many of the drugs need intravenous
  admin
• Unit costs of vector control and active case
  detection need to be synchronized
• Costs associated with public training,
  surveillance etc
• Mathematical model

23
Threat

• Co-infection with other emerging infections
  rendering leishmaniasis a neglected disease of
  Africa

24
What are we doing?

• Mathematical models
• consider the dynamics of the disease between
  three different populations,
• -human host
• -animal reservoir and
• -vector population

25
Model
26
Basic reproduction number

• numerical solution shows that human treatment is
  the key parameter in the disease control among
  human population, but is not sufficient to
  eliminate the disease, even if it is high and
  effective.
• to eradicate the disease from the community high
  rate of human treatment should be followed by
  vector control strategies by either using treated
  bed-nets
• or direct killing of sand flies, and reservoir
  control strategies either by killing all
  infective reservoirs
• or by separating all reservoir from humans to a
  safe distance.

27
END..

• THANK YOU
• and special thanks to DIMACS