Vectorborne Infectious Disease Vector A living organism usually

Vectorborne Infectious Disease

Vector • A living organism, usually an insect or other arthropod, that can transmit a communicable disease agent to a susceptible host.

Vectorborne Disease Outbreak (VBDO) · The occurrence of two or more cases of a vectorborne disease · Risk increases with: - Improper handling of waste water - Inadequate drainage of rainwater - Improper management of solid waste

Climate Sensitive Diseases • Vectorborne Diseases: – Malaria (Mosquito) – Dengue Fever (Mosquito) – Lyme Disease (Tick) – Rocky Mountain Spotted Fever (Tick) – Erlichiosis (Tick) – Other vectorborne viruses

Vector Transmission • mechanical transmission the transfer of a pathogen from an infectious source to a susceptible host by a vector without any reproduction or developmental changes in the pathogen • biological transmission the transfer of a pathogen to a susceptible host by a vector, with the pathogen undergoing reproduction, developmental changes, or both in the vector

Insects as Vectors • Man as Principal Host – anthropophilic species that usually feed on humans. "human loving“ – Ex. dengue, epidemic typhus, filariasis, malaria, relapsing fever, yellow fever (urban) • Man as Incidental Host – zoonosis diseases of animal transmissible to man – Ex. African sleeping sickness, Chaga’s disease, encephalitis, hemorrhagic fever, leishmaniasis, plague, tularemia, yellow fever (jungle)

Orders of Insect Vectors • Anoplura (anopl = unarmed; ura = tail) the sucking lice, containing the human head and body lice. • Diptera (di = two; ptera = wings) the flies, gnats, midges, and mosquitoes. • Hemiptera (hemi = half; ptera = wings) the true bugs, including the conenose bugs (which transmit Chagas' disease) and the bed bugs. • Orthoptera (ortho = straight; ptera = wings) the cockroaches, crickets, grasshoppers, katydids, mantids, and walking sticks. • Siphonaptera (siphon = tube; aptera = wingless) the fleas. • Acari the ticks.

Anoplura (sucking lice) • Pediculidae: includes the human head and body louse (Pediculus humanus and Pediculus capitis) • Pthiridae: contains the human pubic louse or crab louse (Pthirus pubis).

Diptera (The Flies and Mosquitoes) • Culicidae: The mosquitoes – 3000 species worldwide, 150 in North America • Muscidae: the muscid flies – Contain the house fly and the tsetse fly • Simuliidae: the black flies – 1000 species worldwide • Pscyhodidae: sand flies • Ceratopogonidae: the biting midges • Tabanidae: the horse and deer flies – 3000 species worldwide

Mosquitoes Aedes spp. vectors of dengue, yellow fever, La. Crosse encephalitis, filariasis, other viruses Culex and Culiseta spp. vectors of SLE, EEE, VEE, WNV, RVF, filariasis, Anopheles spp. vectors of malaria, filariasis, heartworm Mansonia spp. Vectors of filariasis, RVF, WNV, Sindbis, other viruses Ochlerotatus spp. WNV, JEE, other viruses

West Nile Virus 1999

West Nile Virus 2000

West Nile Virus 2001

West Nile Virus 2002

West Nile Virus 2003

West Nile Virus 2004

West Nile Virus 2005

West Nile Virus 2006

WNV Human Cases 2006

WNV Bird Cases 2006

WNV Veterinary Cases 2006

New Routes of Exposure

Muscid Flies House fly (Musca spp. )- mechanical vector of filth diseases (ex. Salmonella, Cryptosporidium, E. coli, etc. ) Tsetse fly (Glossina spp. )- biological vector of African Trypanosomiasis

Black Flies Black flies (Simuliidae) are biting flies that serve as vectors for Onchocerciasis (River Blindness) Onchocerciasis is caused by Onchocerca volvulus, a parasitic worm that lives for up to 14 years in the human body

Sand Flies Phlebotomine sand flies are vectors of various pathogenic agents responsible for diseases of animals including man : leishmaniases, bartonellosis and various arboviroses

Leishmaniasis • Parasitic disease caused by obligate intracellular protozoa of the genus Leishmania spread by the bite of infected sand flies • Several different forms of leishmaniasis – cutaneous (cue-TAY-knee-us) leishmaniasis, which causes skin sores – visceral (VIS-er-al) leishmaniasis, which affects some of the internal organs of the body (for example, spleen, liver, bone marrow).

Deer Flies Deer flies (Chrysops spp. ) may serve as vectors for Tularemia and Loa (loiasis)

Hemiptera (true bugs) • Reduviidae - assassin and conenose or kissing bugs. About 2, 500 species worldwide (subfamily Triatominae vectors Chaga’s Disease) • Cimicidae - bed bugs. At least 75 species worldwide.

Chaga’s Disease • American Trypanosomiasis caused by Trypanosoma cruzi Acute: • Acute symptoms only occur in about 1% of cases. swelling of the eye on one side of the face, fatigue, fever, enlarged liver or spleen, and swollen lymph glands. Sometimes, a rash, loss of appetite, diarrhea, and vomiting occur. In infants and in very young children with acute Chagas disease, swelling of the brain can develop in acute Indeterminate: • Eight to 10 weeks after infection, the indeterminate stage begins. During this stage, people do not have symptoms. Chronic: • Ten to 20 years after infection, people may develop the most serious symptoms of Chagas disease. Cardiac problems, including an enlarged heart, altered heart rate or rhythm, heart failure, or cardiac arrest are symptoms of chronic disease. Chagas disease can also lead to enlargement of parts of the digestive tract, which result in severe constipation or problems with swallowing. Not everyone will develop the chronic symptoms of Chagas disease.

Orthoptera (roaches) • Mechanical vectors • Several families – Most important include: • Periplaneta (American cockroach) • Blatella (German and Oriental cockroaches)

Siphonaptera (the fleas) • Ceratophyllidae - mainly associated with rodents • Leptopsyllidae • Pulicidae - several species of human pests • Tungidae - chigoe fleas

Plague • Yersinia pestis • Two forms: – Bubonic – Pneumonic • Transmission from Rodents via flea

Acari (the mites and ticks) • Ixoididae – Ixodes and Dermacentor (hard ticks) • Argasidae – Orithodoros (soft ticks)

Lyme’s Disease • Borrelia burgdorferi • red, slowly expanding rash (called erythema migrans or EM) • Neurologic and muscular symptomology, arthritis • Named after cluster of cases in Lyme, CT in 1970’s • First observed in early 20 th century

Rocky Mountain Spotted Fever • Rickettsia rickettsii • Clinical description – A tickborne febrile illness most commonly characterized by acute onset and usually accompanied by myalgia, headache, and petechial rash (on the palms and soles in two thirds of the cases).

Vertebrate Vectors • • • Dogs Cats Raccoons Bats Mice Etc.

Rabies • Rhabdoviridaenonsegmented, negative-stranded RNA genomes • Illness is acute encephalitis in all warm-blooded hosts, including humans, and the outcome is almost always fatal

Hantavirus Pulmonary Syndrome Cases by State of Exposure United States – September 19, 2006 Total Cases (N=453 in 30 States) 0 Cases 1 -4 Cases 5 -9 Cases >=10 Cases Twenty-seven cases were reported with unknown state of exposure.

Characteristics of Hantaviruses • No arthropod vector established Unique among genera of Bunyaviridae • Rodent hosts Genus and possibly species specific • Transmission Aerosolization of rodent excreta

Transmission of Hantaviruses Chronically infected rodent Horizontal transmission of infection by intraspecific aggressive behavior Virus also present in Virus is present in throat swab and feces aerosolized excreta, particularly urine Secondary aerosols, mucous membrane contact, and skin breaches are also sources of infection

Peromyscus maniculatus Deer mouse Sigmodon hispidus Cotton rat

Family Sin Nombre Virus Characteristics Bunyaviridae Transmission vertebrate hosts, no arthropod vectors Viral particles spherical, 80 -120 nm Structural proteins Glycoproteins: G 1, G 2 nucleoprotein: N Genome ss-RNA, trisegmented, negative polarity

Rodent Exposure 70 confirmed HPS cases Peridomestic exposure 69% (48/70) Peridomestic & occupational exposure 19% (13/70) Peridomestic & recreational exposure 9% (6/70) Occupational exposure 4% (3/70) Entering/cleaning rodent-infested structures 9% (6/70) Armstrong, L. R. et al. , JID 1995; 172 (October)

Prevalence of SNV Ig. G Antibodies in Select U. S. Populations Risk group Postive/tested (%) Location/time Forest workers 1 Health care workers 2 Prodromal HPS 3 Contacts 4 Rural OCC 5 Rodent workers 6 0/143 0/396 3/299 (1. 0%) 3/239 (1. 3%) 1/522 (0. 2%) 8/932 (0. 9%) SW US, 1993 SW US, 1994 Total 15/2531 (0. 6%) 1. Vitek et al, 1996 4. Zeitz et al, 1995 2. Vitek et al, 1996 5. Zeitz et al, 1995 3. Simonsen et al, 1995 6. Armstrong et al, 1995

HPS Prevention Control Mice Inside Control Mice Outside Use Safety Precautions