Disease Co-infection Patterns in Lions in the KNP Danny Govender, - - PowerPoint PPT Presentation

Disease Co-infection Patterns in Lions in the KNP

Danny Govender, Anna Jolles, Heather Broughton

Agriculture vs Conservation

• In large free-ranging systems disease is seen as

an important driver

• When would we be concerned?

1) Small populations exposed to emerging diseases 2) Disease dynamics that are slower than host dynamics providing little selective pressure 3) Synergistic co-infections with other parasites that may alter hosts ability to respond to disease challenge.

Most organisms are parasites…

… numerically, and in terms of species richness

Most individual hosts, and all animal populations, are infected with multiple parasites.

More specifically, are there parasite species that play a keystone role in structuring the parasite community found in a host population? So, what processes structure parasite communities sharing a host population?

Parasites interact via ecological and immunologic mechanisms:

• Ecological mechanisms (bottom up):

– Direct competition for space / resources – Chemical or mechanical modification of the host environment – Ecological interference

Immunological mechanisms (top-down):

i. Immunosuppression ii. Cross-immunity to similar parasites

• iii. Co-regulated immune responses to micro-and macroparasites

Intracellular parasites e.g. Viruses, some bacteria Extracellular parasites e.g macroparasites

Th1 Th2 downregulation

Humoral immunity Cell-mediated immunity

What makes a keystone parasite?

broad effects on many other parasite species; most likely by:

• Suppressing or biasing host immunity.
• Being reasonably common in the host population

( not extremely virulent).

• Causing lasting immunological changes in

individual hosts ( chronic infections).

Candidate parasite taxa:

• Chronic macroparasitic infections, e.g. GI

helminths

• Chronic microparasitic infections, e.g.

– Mycobaterium TB complex – Immunodeficiency viruses!

Study system: FIV in African lions.

• Lentivirus closely related to HIV and SIV.
• Spread via bites and scratches.
• Broader cell tropism than HIV.
• Most felids infected with strains of FIVs.
• Causes feline AIDS in domestic cats.
• Causes increased aggression in domestic cats..
• FIV in lions relatively benign.
• Coinfection consequences of FIV in lions not yet studied.

Lion population of Kruger National Park, South Africa

• Approx 1700 lions
• Prides of 5-15 individuals
• Territories 40-90km2 in south, 300-600km2 in north
• Female pride membership stable; adult male pride

tenure ~ 2 yrs.

• Many infections, viral, GI parasite, hemoparasite,

bacterial…

Pilot study - aims:

• 1. Assess age-sex &

geographic distribution of FIV infection in KNP lions.

• 2. Evaluate clinical effects

and coinfections.

• 3. Establish immunological

tools for lions.

Methods

• Work in conjunction with ongoing lion

demographic study.

• Captures in 30 prides.
• Basic clinical assessment, sample

collection.

• Viral serology, fecal parasitology.
• Hematology, BKA, LPA, flow cytometry.

Pilot study results – FIV distribution:

• 62 lions captured April 2010, southern KNP
• 37 lions captured Aug 2010, northern KNP
• FIV prevalence: 53%

FIV seroprevalence increases with age (χ2 = 12.01, p = 0.0005) Prevalence may be higher in males than females (63.4% vs. 45.5%; χ2 = 2.95, p = 0.08) No difference in seroprevalence between north and south (χ2 = 0.06, p = 0.81).

Pilot study results – clinical data:

FIV+ lions may be more likely than FIV- lions to suffer from:

• Ocular lesions (χ2 = 3.5, p = 0.06)
• Gingivitis (χ2 = 2.91, p = 0.09)
• Enlarged lymph nodes (F ratio = 4.02, p < 0.05)

No differences detected in body mass, condition, hygromas, bites & scratches, coat, dehydration..

Pilot study results – immunology:

• Bacterial killing assay
• Lymphocyte proliferation

assay

• Flow cytometry

Pilot study results – coinfections:

• FIV+ lions have a richer parasite community

(viruses, GI parasites, hemoparasites) than FIV- lions (F ratio = 5.01, p = 0.0325)

• FIV+ lions are less likely to seropositive for

canine distemper (17% vs 28% prevalence; χ2 = 3.99, p = 0.046);

• but more likely to be infected with ascarids (62%

vs 43% prevalence; χ2 = 4.58, p = 0.032).

• No differences detected for infections with

parvovirus, calicivirus, coronavirus, tapeworm, hookworm, coccidia, toxoplasma.

Future work (2011)-

• Central area capture: Sep 2011
• Trouble-shoot flow cytometry
• Hemoparasite PCR panel
• Expand sample size for immune assays
• Track movement and behavior…

Thanks!

– SANParks Veterinary Wildlife Services and Scientific Services – Sam Ferreire, Darius Schoultz, Travis Smit for use of their photos – Morris Animal Foundation – Lion Demography Project (PIs Sam Ferreira and Paul Funston)