HIV and Parasite Load. Keith Keller

Transcription

1 HIV and Parasite Load Keith Keller

2 HIV: Human Immunodeficiency Virus Retrovirus that infects CD4+ T Cells Uses host cell s mechanics to reproduce, by means of reverse transcriptase and integrase which is brought into host cell by virus Cytotoxic T cells (CD8+) attack infected CD4+ cells HIV leads to drastic drop in CD4+ cells which allows for opportunistic infections to thrive ~34.2 million people are infected with HIV worldwide (

3 Geographic Distribution of HIV Prevelance

4 T Cells: CD8+/CD4+ Called T Cells because they mature in the Thymus, rather than the Bone marrow (B cells) T Cells are part of the adaptive immune system, and function to prime the innate immune system and destroy foreign pathogens. CD4+ (helper T cells): Involved in activation of cytotoxic T cells, and secrete cytokines that facilitate different immune responses CD8+ (cytotoxic T cells): Destroy virally infected cells Regulatory T cells (Treg): Regulate immune responses. Play a large role in self tolerance. Memory T cells: Antigen specific T cells that play a role in memory of past infections, which leads to a quicker response upon reinfection. (Janeway s Immunobiology. 2010)

5 HIV and AIDS HIV becomes AIDS when the patients T cell count drops below 200 (1/ul) as well as the presence of opportunistic infections.

6 Parasite Opportunistic Infections (POIs) Most opportunistic parasite infections are protozoan. (Kurniawan, A. et al. 2009) Cryptosporidium parvum, Isospora belli, Entamoeba histolytica/dispar appear to be the most common in HIV/AIDS patients. (Lindo, John F. et al. 1998) While these are the most common, so common that they are considered to be AIDS defining illnesses (ADIs), they are hardly the most problematic Parasites such as: Toxoplasma gondii, Leishmania spp. and Trypanosoma cruzi present much bigger health risks (Nissapatorn, V. et al. 2011)

7 POIs Continued Opportunistic infections over time

8 Prevalence Leishmania spp. and Trypanosoma cruzi are mostly found to infect those where sanitary conditions may be poor These infections happen to correlate with high prevalence of HIV infection. Eg. Africa, South America and Asia Toxoplasma gondii appears to be more cosmopolitan in its distribution. That is, it is prevalent in both developed and undeveloped countries

9 Danger of POIs Since the body is considered immunocompromised when infected with HIV/AIDS, these POIs are able to avoid the host s immune system and thrive In particular, diseases such as toxoplasmosis, leishmaniasis, and Chagas disease are extremely harmful Death from HIV/AIDS is often due to the OIs and cancer, rather than the virus itself

10 Leishmaniasis Visceral leishmaniasis has been shown to increase tenfold in HIV/AIDS patients due to decreased immune response. (Nissapatorn, V. et al. 2011)

11 Toxoplasmosis Medically the most important POI in HIV patients due to widespread prevelance (Nissapatorn, V. et al. 2011) 95% of cerebral toxoplasmosis (CT) occurs due to reactivation of latent stage Toxoplasma CT is most common in AIDS patients

12 Toxoplasmosis distribution in HIV patients Seroprevelance of Toxoplasmosis in HIV infected patients (Nissapatorn, V. et al. 2011) Light red=>60% Brown=40 60% Blue=20 40% Yellow=10 20% Green=<10%

13 Chagas disease Particularly prevalent in South America Co infection with HIV and T. cruzi infection can reactivate a latent T. crui infection due to immunosuppression by HIV (Nissapatorn, V. et al. 2011) Chagas disease can cause high a mortality rate in HIV patients

14 Importance While parasites are not the only cause of OIs, it is important to understand why they are dangerous Their efficacy and prevalence increase within those who are immuno compromised Treatment and therapy becomes less effective Though some of these diseases, such as toxoplasmosis, cryptosporidosis, E. hystolitica etc. may not be particularly harmful in healthy hosts, they can ravage those who are susceptible

15 Preventative Measures As with most disease prevention, it is important to avoid contaminated water and soil sites. T. gondii: avoid litter boxes; don t eat undercooked meat; wash your vegetables Leishmania spp., and T. cruzi: Use bed nets in endemic areas, use bug repellent

16 Treatment Highly active antiretroviral therapy (HAART) Shown to effectively suppres HIV viral load Has been reported to help control protozoan infections (Pozio, E. 2004)

17 Works Cited Nissapatorn, Veeranoot, and Nongyao Sawangjaroen. "Parasitic infections in HIV infected individuals: diagnostic & therapeutic challenges." The Indian journal of medical research (2011): 878. Pozio, E. "[Highly Active AntiRetroviral Therapy and opportunistic protozoan infections]." Parassitologia (2004): Kurniawan, A., et al. "Intestinal parasitic infections in HIV/AIDS patients presenting with diarrhoea in Jakarta, Indonesia." Transactions of the Royal Society of Tropical Medicine and Hygiene (2009): Murphy, K. Janeway s Immunobiology, 8 th edition. Garland Science Lindo, John F., et al. "Intestinal parasitic infections in human immunodeficiency virus (HIV) positive and HIV negative individuals in San Pedro Sula, Honduras."American Journal of Tropical Medicine and Hygiene 58.4 (1998):