Infectious Diseases and
Parasite Vectors
Daniel Wyton
Ectoparasitism
• Examples of ectoparasites
included lice, mites, and ticks.
• In a number of diseases caused
in humans these parasites act
as vectors for the
virus/bacteria which once they
have entered into humans
cause diseases.
Lice
• Humans can be the host to
three different lice: head,
pubic, and body.
• Lice spread from person to
person via contact and while
on their host they take blood
meals many times a day.
• Body lice are the main carriers
of epidemic typhus
Rickettsia & Rickettsia prowazekii
• Typhus is caused by bacteria of the genus
Rickettsia.
• The members of this genus cause a number of
diseases known as the spotted fevers, along with
these diseases they also cause Epidemic
typhus.
• The main causative agent of Typhus is R.
prowazekii.
Typhus Risk
High level of infection
Cluster of infections
Only sporadic cases
Infection by R. prowarzekii
• R. prowazekii and the Louse
• R. prowazekii in Humans
▫ Poor hygienic conditions
• R. prowazekii in Reservoir Hosts
Symptoms
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Chills
Cough
Delirium
High Fever
Photophobia
Rash which covers the whole body
Severe headaches and muscle pain
Coma
Diagnosis and Treatment
• Blood Tests
▫ Typhus antibodies
▫ Liver enzymes (ex. albumin)
▫ Kidney failure
• Treatment for the R. prowazekii usually involves
one of two antibiotics:
▫ Tetracycline
▫ Doxycycline
Fleas
• Small arthropods that live on
the surface of animals.
• Xenopsylla cheopis, the
Oriental rat flea
▫ Carriers of the famous
bacteria, Yersinia pestis.
Fleas
Yersinia pestis
• A gram-negative bacteria
which is transferred within the
blood.
• Causative agent of Plague.
• Causes 3 types of Plague in
infected individuals.
▫ Bubonic
▫ Septicaemic
▫ Pneumonic
Y. pestis and the Black Death
• Noted Outbreaks
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6th century – Roman Empire
1348-1350 – Europe
1665 – London
18th century
• Death toll
• Effects
Infection by Y. pestis
• Infection in Fleas
• Infection in Rats, Rattus rattus
• Infection in Humans
Symptoms
• Bubonic
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Chills
Swollen lymph nodes, bubos
Fever
Pain in area of infection
• Septicaemic
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Stomach pain
Organ failure
Vomiting
Clotting problems in blood
• Pneumatic
▫ Difficulty breathing
▫ Severe cough
▫ Bloody phlegm
Diagnosis and Treatment
• Diagnosis
▫ Blood and Lymph tests
• Treatment
▫ Antibiotics
▫ Quarantine
▫ Vaccines
Ticks
• Ticks live on their hosts and
take blood meals until they
become engorged.
• Carriers of a set of illnesses
called arboviruses
(Arthropod-Bourne Viruses)
Crimean-Congo Hemorrhagic Fever
• Caused by a virus of the family Bunyaviridae
• Ixodid ticks
• Transmission
• Reservoir Hosts
• Infections in Humans
▫ 4 Stages
• Emergence
Symptoms
• Pre-Hemorrhagic
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Photophobia
Fever
Chills
Severe Headache
• Hemorrhagic
▫ Large bruises
▫ Bursting of Capillaries
Diagnosis and Treatment
• Diagnosis
▫ Blood and Tissue Tests
▫ ELISA
• Treatment
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Drugs
Blood Transfusions
Plasma Transfusions
Vaccine
References
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www.who.int/en/
www.cdc.gov/
www.ncbi.nlm.nih.gov/
Brachman, P. S. and A. S. Evans. (1998). Bacterial Infections of Humans:
Epidemiology and Control. New York, NY: Plenum Medical Book Company.
• Chamroonkul, N., U. Khow-Ean, W. Mitarnun, B. Ovartlarnporn and K. Silpapojakul.
(1996). Liver involvement in murine typhus. QJM-Monthly Journal of the
Association of Physicians. 89:623-629
• Chinikar, S., S.M. Ghiasi, A. Haeri, R. Hewson and M. Moradi. (2010). CrimeanCongo hemorrhagic fever in Iran, and neighbouring countries. Journal of Clinical
Virology. 47:110-114.
• Ammerman, N.C., A.F. Azad, M. Beier-Sexton, J.J. Gillespie and B.S. Sobral. (2009).
Veterinary Research. 40:12.
Questions?