1. Arthropod Transmission Of Disease

2. What is an ‘Arthropod-borne Disease’? A disease transmitted by an arthropod So… “Why is it important for public health staff to understand arthropod-borne diseases?”

3. ‘Top 5’ reasons to address arthropod-borne diseases 5. Arthropod-borne diseases occur world-wide, including Afghanistan 4. They’re making a comeback throughout the world 3. Afghans are highly susceptible to these diseases (both physically and mentally) 2. Very few vaccines exist for these diseases 1. MOST IMPORTANT: Military history shows complacency, and ignorance of these vitally important diseases kills and sickens troops

4. Prevent Disease, Disability and Premature Death OBJECTIVE هدف Explain disease cycles and control measures of vector-borne diseases.

5. Overview مرور TransmissionCyclesTypes

6. Let’s use life cycles to study arthropod-borne diseases What’s a life cycle? It’s just a map that shows you how a “germ” infects people Next slide is an example

7. Types of Life Cycles Three-factor cycle - African sleeping sickness (trypanosomiasis) - it involves a human, a fly, and the trypanosomiasis germ. Trypanosomiasis germ (T.b. gambiense protozoa) in the blood of the infected human is ingested by a fly. Fly bites an uninfected human and transfers the Trypanosomiasis-causing germ to the human. 1. Host 2. Pathogen 3. Vector Tse tse fly

8. Types of Life Cycles Four-Factor (Complex Cycle) - a disease of animals that can be transmitted to humans Also known as a complex cycle Plague bacterium is in the rodent’s blood Flea ingests bacteria when it feeds on blood Flea regurgitates bacteria into rodent when it feeds Some fleas may move to humans, feed, and transmit the plague bacteria. 1. Host2. Pathogen 3. Vector4. Reservoir

9. Terms and Concepts You need to know the vocabulary of arthropod-borne diseases because: They use these terms at your public health office (it’s nice to understand the conversation) The literature you’ll read at work uses these terms (it’s nice to understand your readings)

10. Prevent Disease, Disability and Premature Death Terms and Definitions Host – person or living animal that provides food and lodging to the infectious agent Parasite – an organism that lives on or in another organism or gets its food from that organism

11. Prevent Disease, Disability and Premature Death Terms and Definitions Pathogen – a parasite that causes disease Arbovirus – virus carried by arthropods Vector – a living non-human carrier of a pathogen Reservoir – any person, animal, arthropod, plant, soil or substance in which an infectious agent normally lives and multiplies **In some cases a reservoir can also be a host (i.e. dengue fever)**

12. Prevent Disease, Disability and Premature Death Terms and Definitions Transmission Mechanisms: Mechanical Disease Transmission – parasite is carried accidentally on or in a vector’s body (but does not go through sexual changes in the vector)

13. Prevent Disease, Disability and Premature Death Terms and Definitions Transmission Mechanisms: Biological Disease Transmission – occurs when a pathogen multiplies and/or undergoes sexual growth changes in a vector’s body Malaria

14. Prevent Disease, Disability and Premature Death Terms and Definitions Inoculation Mechanisms: Active Inoculation – pathogen is introduced into a host by the bite of an infected vector Passive inoculation – pathogen is introduced to the host by rubbing vector feces or other infective material into a feeding wound, skin abrasion, or mucous membrane

15. Prevent Disease, Disability and Premature Death Terms and Definitions Transovarial transmission – pathogens are passed on from infected female to her eggs Female mosquitoMosquito eggs

16. Prevent Disease, Disability and Premature Death Terms and Definitions Passage of Disease between regions: Imported Disease – disease acquired in one area and diagnosed in another Introduced Disease – disease acquired in one area, then brought into another area, and acquired by a second individual AB AB

17. Prevent Disease, Disability and Premature Death Questions?سوالات

18. Part 2 Arthropod Transmission Of Disease

19. Introduction We covered Definitions in Part 1 -- Any questions on those? Apply those concepts to specific vector- borne diseases of particular importance... starting with...

20. Mosquito – Borne Diseases

21. Prevent Disease, Disability and Premature Death Malaria An acute & chronic disease caused by parasitic protozoans in the genus Plasmodium. Transmitted by certain Anopheles species mosquitoes. A complex 3-factor vector-borne disease of the blood. >1 pathogen species, vector species, man, complicated ecology

22. Prevent Disease, Disability and Premature Death Four Plasmodium species cause human malaria: P. falciparum -- malignant tertian malaria. P. vivax -- benign tertian malaria. P. malariae -- quartan malaria. P. ovale -- tertian malaria.

23. Prevent Disease, Disability and Premature Death The Malaria Pathogen Life Cycle Is Complex The primary (or sexual) cycle is in the mosquito. Parasites ingested from an infected host develop into sexual forms which mate & reproduce. Infective forms migrate to the mosquito’s salivary glands where they are introduced into the next host while the mosquito is feeding.

24. Prevent Disease, Disability and Premature Death The malaria pathogen life cycle is complex The secondary (asexual, generative) cycle occurs in humans. The pathogens initially enter cells in the liver where they continue their development. The parasites then emerge and invade red blood cells. Once in the red blood cells they multiply asexually and produce huge numbers of parasites, which attack additional red blood cells.

25. Prevent Disease, Disability and Premature Death

26. Symptoms Symptoms Symptoms occur when red blood cells (RBCs) rupture to release pathogens that have multiplied within them. When enough RBCs are affected, anemia develops.

27. Prevent Disease, Disability and Premature Death Symptoms Symptoms In falciparum malaria, RBCs “stick together” causing blocked capillaries, which then rupture -- When this happens in the brain, cerebral hemorrhage may cause brain damage and/or death. The liver and spleen may also become grossly enlarged.

28. Prevent Disease, Disability and Premature Death Symptoms Symptoms Commence 10-28 days after an infective mosquito bite. Initially anorexia, headache, fever, flu-like symptoms. After a period, RBCs rupture to release pathogens at the same time, each 2 or 3 days, depending on the species. Release causes chills, high fever & profuse sweating.

29. Prevent Disease, Disability and Premature Death Symptoms Symptoms Other symptoms may include headaches, nausea, vomiting, muscle & joint pains Over time -- anemia, cerebral hemorrhage, impaired liver function.

30. Prevent Disease, Disability and Premature Death Treatment ChloriquinePrimaquineDoxycycline

31. Malaria Distribution

32. Prevent Disease, Disability and Premature Death Epidemiology Epidemiology Malaria is widespread throughout the tropical countries of the world. Transmission can also occur by blood transfusions & hypodermic needles. Communicability lasts as long as malaria pathogens are in the blood. Susceptibility is universal, but a previous case gives some protection. Diagnosis is by finding malaria pathogens in blood by examination of blood smears, or from symptoms.

33. Prevent Disease, Disability and Premature Death Vector Malaria is biologically transmitted only by certain species of Anopheles mosquitoes Most Anopheles cannot transmit malaria. There are 6 main Anopheles vectors in Afghanistan: a. Anopheles superpictus a. Anopheles superpictus b. A. culicifacies c. A. stephensi d. A. hycranus e. A. pulcherrimus f. A. fluviatilis

34. Prevent Disease, Disability and Premature Death Prevention Prevention Personal protection from Anopheles mosquito bites -- including use of repellents & chemoprophylaxis. Reduction of host habitat (if feasible). Pesticides for vector control (if feasible). Education on how & when to use the above.

35. Prevent Disease, Disability and Premature Death Questions?سوالات

36. Dengue An acute, febrile illness caused by an arbovirus & transmitted by mosquitoes. A simple 3-factor vector-borne disease. There are 4 serological types (serotypes) & two clinical forms: Benign (Classical) Dengue, or “breakbone fever.” Dengue Hemorrhagic Fever (DHF) or Dengue Shock Syndrome (DSS).

37. Symptoms Benign dengue symptoms include: Fever (101°F). Severe headache, muscle & joint pain (“breakbone”) & sometimes a flat rash. Commence 5 - 6 days after the infective mosquito bite & last 5 - 7 days. Recovery is usually uneventful. Patients are infective to another mosquito 1 - 4 days after their symptoms occur.

38. Symptoms DHF & DSS symptoms include: Bleeding of the gums, nosebleeds, gastrointestinal bleeding, & dengue shock syndrome. Death is most often due to internal bleeding or shock.

39. Hemorrhaging -- on arm of child

40. Treatment Classical dengue None Supportive, TLC – aspirin is not advised DHF/DSS Intravenous (IV) transfusions & fluids to prevent shock, & with corticosteroids.

41. Epidemiology Found throughout much of the tropical world, particularly in Mexico, Caribbean, central America, west Africa, & south Asia. Dengue Hemorrhagic Fever kills thousands of south Asian children annually.

42. Epidemiology Transmitted by the bite of infective Aedes species mosquitoes, principally Aedes aegypti.

43. Vector Aedes aegypti, yellow fever mosquito Daytime biter, weak flyer, never found more than about 400 meters from human habitation Not able to overwinter in cold areas. Larvae are found in water in artificial containers: cans, rain gutters, & particularly rubber tires.

45. Epidemiology of Dengue Vectors = Aedes aegypti Aedes albopictus

46. Prevention Prevention Personal protection from mosquito bites Isolating infective people from mosquito vectors Reduction of mosquito habitat (if possible & feasible) Pesticides (if feasible) Education about the above. It’s #1!!!

47. The Arboviral Encephalitides “Arthropod Borne Viruses” = Arbovirus

48. The Arboviral Encephalitides... Acute infections of the brain and/or spinal cord Encephalitides is the plural of encephalitis -- includes more than one encephalitic disease. Complex four-factor vector-borne diseases. May be mild to fatal

49. The Arboviral Encephalitides There are over 100 arboviruses that produce disease in humans. Transmission is by the bite of an infected arthropod (including mosquitoes, sand flies, ticks)

50. Mosquito-borne Encephalitides In the Afghanistan there are several types : Japanese Encephalitis Infections may occur nationwide. Sindbis Fever Probably not endemic nationwide. West Nile Virus Probably not endemic to Afghanistan but may be more common in desert environments.

51. Symptoms/Treatment Symptoms/Treatment Range from asymptomatic, through general flu-like illness, to severe central nervous system (CNS) damage or death. Usually fever, headaches & drowsiness. Sometimes vomiting, stiff neck, tremors, confusion, & convulsions. Severity varies by species of virus. Incubation period from infective bite to sickness ranges from 2 - 20 days. Treatment is supportive -- there is no medicine to kill just the virus.

52. Epidemiology Epidemiology The epidemiology of the mosquito-borne encephalitides is complex Several vectors & reservoirs, & much is unknown. All humans without previous exposure to a given virus are susceptible to infection Certain viruses “prefer” certain age groups. Mosquitoes cannot pass arboviral encephalitis from one human to another.

53. Vector In Afghanistan, arboviral encephalitides are spread only by mosquitoes. Several species of Aedes, Culex, & others are involved.

54. Prevent Disease, Disability and Premature Death Reservoir ??? Japanese Encephalitis-Birds. West Nile Virus – Birds. Sindbis Fever-Birds, rodents. Many other reservoirs are possible: rodents, bats, reptiles, amphibians, etc.

55. Prevention Personal protection from mosquito bites. Reduction of mosquito habitat (if feasible). Surveillance for vectors & pesticides for control (if necessary). Monitoring with sentinel chickens. Education about the above.

56. Tick-Borne Diseases

57. Crimean Congo Hemorrhagic Fever Tick-borne disease caused by a Nairovirus in the family Bunyaviridae. It is primarily transmitted by a bite or exposure to hard ticks (Family Ixodidae) in the genus Hyalomma. Tick-borne disease caused by a Nairovirus in the family Bunyaviridae. It is primarily transmitted by a bite or exposure to hard ticks (Family Ixodidae) in the genus Hyalomma.

58. Symptoms Symptoms Sudden, with initial signs including headache, high fever, back pain, joint pain, stomach pain, and vomiting. Other symptoms include red eyes, flushed face, a red throat, and red spots on the palate. Symptoms may also include jaundice, and in severe cases changes in mood and sensory perception. As the illness progresses, large areas of severe bruising, severe nosebleeds, and uncontrolled bleeding at injection sites can be seen, beginning about on the fourth day of illness and lasting for about two weeks. Fatality rates in hospitalized patients range from 9% to 50%. Diagnosis is by laboratory tests and clinical findings.

59. Treatment Treatment is primarily supportive, and attention to fluid balance and correction of electrolyte abnormalities, oxygenation, and hemodynamic support, as well as appropriate treatment of secondary infections. The antiviral drug ribavirin has also been used for treatment with some benefit. Treatment is primarily supportive, and attention to fluid balance and correction of electrolyte abnormalities, oxygenation, and hemodynamic support, as well as appropriate treatment of secondary infections. The antiviral drug ribavirin has also been used for treatment with some benefit.

60. Epidemiology In Afghanistan, there is nationwide evidence of CCHF viral antibodies. Habitats that are conducive to tick occurrence are dry areas, including animal stables, trails, and former pastures. CCHF is maintained in nature by Hyalomma ticks. Soft ticks (Family Argasidae), such as Ornithodoros lahorensis are also considered secondary vectors and are often found in animal stables. Numerous wild and domestic animals, such as cattle, goats, sheep, and hares, serve as amplifying hosts for the virus.

61. Epidemiology CCHF is transmitted to humans biologically by the bite of an infected tick (active inoculation) or exposure to infected blood (passive inoculation). It can be transmitted from human to human by contact with infectious blood or fluids, or improper sterilization of medical equipment. The transmission period is primarily from May-October. Animal herders, livestock workers, and slaughter houses in endemic areas area at risk of CCHF. Healthcare workers in endemic areas are also at risk.

62. Vector CCHF vectors in Afghanistan are: Hyalomma marginatum (Primary vector) H. anatolicum, H. detritum, H. dromedarii, H. impeltatum, H. schulzei, and H. asiaticum; also the soft tick Ornithodoros lahorensis (Secondary vectors)

63. Prevention Personal protection measures against ticks, including self-inspection & “buddy” inspection. Tick control -- may be of limited effectiveness & use. Education.

64. Miscellaneous Arthropod-Borne Diseases

65. Plague

66. Plague A zoonotic vector-borne disease caused by the bacterium Yersinia pestis Transmitted by fleas. Historically known as “black death” because of the symptomatic appearance of dark hemorrhagic areas in the skin of infected persons.

67. Septicemic Plague -- Note darkening of skin, hence the term “black death.”

68. Plague A complex two-, three-, or four-factor disease. Can take three forms -- bubonic, septicemic, & pneumonic -- depending on the system & organs affected.

69. Symptoms... Symptoms... Bubonic form (most common) Swollen lymph nodes draining the flea bite, “buboes” in groin, armpit or neck Buboes may be inflamed, painful, & may ooze. Untreated, mortality rate is 50%, but responds well if treated early.

70. Plague buboes in axillum

71. Feline Plague: Sub-maxillary buboes on the neck of a cat

72. Symptoms Symptoms Septicemic form -- “blood” plague. Dissemination in the blood to various parts of the body. Can progress rapidly. Untreated mortality rate is over 90%.

73. Septicemic plague symptoms -- gangrene of fingers and toes

74. Symptoms Symptoms Pneumonic form -- “plague pneumonia” Secondary involvement of the lungs. Person-to-person transmission by sneezing & coughing is a threat, particularly in a hospital environment. Untreated mortality rate is over 90%.

75. Treatment Treatment Must be started immediately. A number of antibiotics work well, but penicillin is not particularly useful. Diagnosis is by microscope examination of blood or bubo fluid or by other laboratory tests -- Early diagnosis is essential.

76. Epidemiology Epidemiology Distribution is throughout much of the world, although large areas are plague- free. Found in many species of wild & domestic animals. Some are asymptomatic carriers, others become symptomatic & die quickly -- All are reservoirs.

77. Epidemiology Epidemiology Plague can be spread by Bite of infected flea (vector transmission), Respiratory aerosols (non-vector transmission) Blood to blood contact, a form of indirect inoculation (non-vector transmission).

78. Epidemiology Epidemiology Plague can thus be -- A 4-factor disease (prairie dog to humans by a flea), or A 3-factor disease (human to human by flea), or A 2-factor disease (human to human by respiratory aerosol or indirect blood to blood inoculation).

79. Epidemiology Epidemiology Incubation period 2 - 6 days from flea bite or blood-blood contact. 2 - 6 days from flea bite or blood-blood contact. 1 - 6 days from aerosol inoculation. Susceptibility is general. Recovery confers some immunity. Excellent vaccine available. Separate cycles in nature for Urban (murine) spread by domestic rodents. Rural (sylvatic) spread by wild rodents.

80. Vector Vector Many species of vector fleas, some much more efficient than others. Can be transmitted from reservoir to reservoir, reservoir to human, & human to human. Transmission most dangerous when flea’s gut is “blocked” by plug of plague bacteria. Flea continues to try to feed, regurgitating contaminated blood through the feeding wound into a new host.

81. Blocked Flea

82. Prevention Prevention Educate everyone at risk on plague avoidance. Use personal protection measures. Implement rodent exclusion & harborage elimination.

83. Prevention Prevention Control fleas in wild rodent burrows Animal control is not always practical, but if attempted, it’s mandatory that fleas are killed first, so they are not actively seeking a new host when their previous one has been killed. Vaccination of at-risk personnel. Contact protection in hospitals, elsewhere as necessary.

84. Prevent Disease, Disability and Premature Death Break

85. “The great scourge of humanity” Epidemic Typhus

86. Caused by the rickettsia Rickettsia prowazekii. Transmitted by the body louse Pediculus humanus humanus. Also known as louse-borne typhus, classical typhus fever, & historically as the “red death.” Complex 3-factor disease

87. Symptoms... Symptoms... Sudden onset with chills, fever, headache, pains, prostration. Body rash appears on the 5th or 6th day. Incubation period 7 - 14 days after infection. Lasts 2 - 3 months unless death occurs first.

88. Symptoms Symptoms Toxemia (blood poisoning) pronounced & severe. Mortality in untreated epidemic typhus can reach 40%. Diagnosis is by laboratory tests -- clinical diagnosis can be difficult except in epidemic situations.

89. Treatment Treatment Various antibiotics until one day after fever breaks.

90. Epidemiology Epidemiology Potential occurrence throughout most of the world. Can originate in & be limited to a defined area -- For example, in 1979, there were: 18,364 reported cases worldwide, 18,278 cases were in Africa, 17,499 cases were in Ethiopian refugee camps (over 95% of the cases for that year).

91. Epidemiology Epidemiology Non-human reservoir doubtful No direct person-to-person transmission. Infection occurs when louse feces or fluids from crushed lice are rubbed into feeding wounds or other breaks in the skin -- Passive inoculation Infection occurs when louse feces or fluids from crushed lice are rubbed into feeding wounds or other breaks in the skin -- Passive inoculation Transmitted biologically Transmitted biologically

92. Epidemiology Epidemiology Epidemic typhus is a risk whenever poverty creates conditions favoring poor hygiene & crowding. Risk increases with wars, famines, & natural disasters creating refugees. Susceptibility is universal, but attack confers long-term immunity. A vaccine is available.

93. Vector Vector Transmitted by the body louse The head louse is a capable secondary vector of endemic typhus, but the pubic louse is not a vector. These species of lice live only on humans.

94. The human body louse, Pediculus humanus humanus

95. Prevention Prevention Improve sanitation & personal hygiene Change clothes, wash clothes & bedding in hot water or bake in oven. Disinsection of clothes on body with insecticidal dusts, or, issuance of permethrin-treated clothing Vaccinate personnel at risk.

96. Leishmaniasis

97. Leishmaniasis Caused by protozoans of the genus Leishmania. Transmitted by sand flies of several species. A complex 4-factor vector-borne disease. 3 species of pathogen Several vector species Complex ecology

98. Leishmaniasis There are 3 clinically separate types caused by separate species of Leishmania: Cutaneous Uta, chiclero ulcer Mucocutaneous (not know to occur in Afghanistan) Papalomoyo, espundia Visceral Kala azar, dumdum fever, tropical splenomegaly

99. Symptoms Symptoms Vary with type of infection...

100. Cutaneous Leishmaniasis Dry or moist ulcerating lesion (usually single) or nodular lesions (usually multiple) May last for months, usually leave large scars. Usually affect ear, face or extremities, unusual on trunk Not fatal but is debilitating & disfiguring. Usually resolve spontaneously in 6 - 12 months.

101. Cutaneous Leishmaniasis

102. Mucocutaneous Leishmaniasis Mucocutaneous Leishmaniasis  Affects face only -- skin, mucous membranes, muscle & bone.  Severely disfiguring if not diagnosed & treated soon after exposure.  Fatalities result from secondary infections, asphyxiation from dislodged tissue.

103. Mucocutaneous Leishmaniasis Untreated case Early stage

104. Visceral Leishmaniasis Chronic disease of lymphatic system, liver, & spleen, with fever, anemia, & progressive, physical wasting away until the patient dies. Mortality is up to 95% in untreated cases - - early detection is vital.

105. Diagnosis Through biopsy cultures from sores, & microscopic & other laboratory tests.

106. Treatment Several medicines are available but early diagnosis is important to prevent disfigurement, or death in the visceral form.

107. Epidemiology of cutaneous & mucocutaneous forms Transmission is biological through active inoculation -- through the bite of an infected sand fly. Non-human reservoirs include dogs, cats, rodents, perhaps other small mammals. No human-to-human infection except for human-to-human contact of abraded skin.

108. Epidemiology of cutaneous & mucocutaneous forms Occurs in pockets throughout Central & South America, Africa, Europe & Asia usually in rural areas. Incubation period is a few days to many months. Susceptibility is universal Immunity to the cutaneous form develops after lesions heal.

109. Leishmaniasis Distribution

110. Vector Transmitted biologically by several species of Phlebotomus sand flies.

111. Prevention Early case detection & treatment. Chemical & cultural sand fly control. Personal protection. Education.

112. Lessons Learned

113. Unpredictable Occurrence of vector-borne diseases can be extremely unpredictable. Outbreaks of disease caused by arboviruses cannot be predicted based upon history. A small area may have a major outbreak, although there was not a single case in the area prior to the outbreak & may not be another case in the area for decades afterwards.

114. The Importance Of Vector Surveillance Disease surveillance is “looking for” a disease. If we know the disease is in the area we can take precautions to prevent it. With vector-borne diseases we can also survey for the vectors through vector surveillance, & control them before they can spread a significant amount of disease.

115. Vector-Borne Disease Threat Military Significance Many areas of the world harbor vector- borne diseases that are only found in those areas & nowhere else. If these areas are of military interest, we must know what vector-borne diseases occur there so we can prevent them in our personnel.

116. Prevent Disease, Disability and Premature Death TransmissionCyclesTypes Summary

117. Questions?سوالات