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  1. 1. Communicable diseases
  2. 2. Vector borne diseases Presented by Deepa Manandhar Lecturer Community Health Nursing
  3. 3. Vector • A vector is a living organism that transmits an infectious agent from an infected animal to a human or another animal. Vectors are frequently arthropods, such as mosquitoes, ticks, flies, fleas and lice.
  4. 4. introduction • Vector-borne diseases are infections transmitted by the bite of infected arthropod species, such as mosquitoes, ticks, bugs, sandflies, and blackflies.
  5. 5. introduction • Vector-borne diseases account for more than 17% of all infectious diseases, causing more than 700 000 deaths annually. They can be caused by either parasites, bacteria or viruses. • Many of vector-borne diseases are preventable, through protective measures, and community mobilization. -WHO 2nd march 2020
  6. 6. Vector borne diseases • Dengue • Malaria • Japanese Encephalitis • Lymphatic Filariasis • Kalazar
  7. 7. malaria
  8. 8. introduction • Malaria is a protozoal disease caused by infection with parasites of the genus Plasmodium and transmitted to man by certain species of infected female Anopheline mosquito. • In the human body, the parasites multiply in the liver, and then infect red blood cells.
  9. 9. Problem statement • In 2021, there were an estimated 247 million cases of malaria worldwide. • The estimated number of malaria deaths stood at 619 000 in 2021.
  10. 10. Problem statement • In 2076/2077, there were total 619 of malaria positive cases reported. – P. falciparum: 56 – P. vivax: 563
  11. 11. Agent Species of Plasmodium infective to humans: Plasmodium falciparum Plasmodium vivax Plasmodium ovale Plasmodium malariae Plasmodium knowlesi
  12. 12. Reservoir of infection Man is the only important reservoir of human malaria.
  13. 13. Host factors AGE : Malaria affects all ages. SOCIO-ECONOMIC DEVELOPMENT Malaria has demonstrated the relationship between health and socio-economic development. It is generally accepted that malaria has disappeared from most developed countries as a result of socio-economic development.
  14. 14. Host factors HOUSING: • The ill-ventilated and ill-lighted houses provide ideal indoor resting places for mosquitoes.
  15. 15. Host factors OCCUPATION: Malaria is predominantly a rural disease and is closely related to agriculture practices. HUMAN HABITS : Habits such as sleeping out of doors, nomadism, refusal to accept spraying of houses, not using measures of personal protection (e.g. bed nets) influence man-vector contact.
  16. 16. Environmental factors (a) SEASON : Malaria is a seasonal disease. It is more common during the rainy season. (b) TEMPERATURE: Temperature affects the life cycle of the malaria parasite. The optimum temperature for the development of the malaria parasite in the insect vector is between 20 deg. to 30 deg.C
  17. 17. Mode of transmission Vector transmission Direct transmission Congenital Malaria
  18. 18. Mode of transmission a) VECTOR TRANSMISSION: Malaria is transmitted by the bite of certain species of infected, female, anopheline mosquitoes. A single infected vector, during her life time, may infect several persons. The mosquito is not infective unless the sporozoites are present in its salivary glands.
  19. 19. Mode of transmission (b) DIRECT TRANSMISSION: Malaria may be induced accidentally by hypodermic intramuscular and intravenous injections of blood or plasma, e.g., blood transfusion, malaria in drug addicts (c) CONGENITAL MALARIA: Congenital infection of the newborn from an infected mother may also occur, but it is comparatively rare.
  20. 20. Incubation period 12 days for P. falciparum 14 days for P. vivax and ovale 30 days for P. malariae 9-12 days for P. knowlesi
  21. 21. Clinical features • The typical attack comprises three distinct stages, i.e., the cold stage, the hot stage and the sweating stage. These are followed by an afebrile period in which the patient feels greatly relieved.
  22. 22. Clinical features • lassitude, headache, nausea and chilly sensation followed in an hour or so by rigors. The temperature rises rapidly to 39- 41°C. • In early part of this stage, skin feels cold; later it becomes hot. Cold stage • The skin is hot and dry to touch. • Headache is intense • The pulse is full and respiration rapid. This stage lasts for 2 to 6 hours. Hot stage • Fever comes down with profuse sweating. • The temperature drops rapidly to normal and skin is cool and moist. • This stage lasts for 2-4 hours. Sweating stage
  23. 23. diagnosis Malaria smear: In this procedure, a film of blood is placed on a slide, stained and examined microscopically. Rapid diagnostic test: To detect the malaria parasite antigen in the blood. Polymerase chain reaction(PCR)
  24. 24. Treatment • Chloroquine is given as anti-malarial drug. • Chloroquine resistant P. falciparum requires treatment with oral quinine given concurrently with pyrimethamine with sulfadoxine and a sulfonamide (e.g. sulfadiazine) • Relapse require same treatment, or quinine alone, followed by tetracycline • Mefloquine may also be used for chloroquine-resistant malaria
  25. 25. Treatment • Artemisinin-based combination therapies (ACTs) are the most effective antimalarial medicines available today and the mainstay of recommended treatment for Plasmodium falciparum malaria, the deadliest malaria parasite globally.
  26. 26. Preventive measures • Prevention of malaria is currently based on two complementary methods: chemoprophylaxis and protection against mosquito bites. • Malaria prophylaxis is not necessary for in-country travel within Nepal. ƒ Prophylactic medication for malaria is recommended for Nepalese traveling to countries with areas of malaria transmission. ƒ The medicine of choice depends on the parasite species and resistance profile in the destination country.
  27. 27. Malaria control programme • Nepal`s malaria control programme began in 1954, mainly in the terai belt of central Nepal with support from United States. • Nepal`s National Malaria Strategic Plan (2014-2025) Vision: Malaria Elimination in Nepal by 2025 Goal: Reduce the indigenous malaria cases to zero by 2022 and sustain thereafter.
  28. 28. Current Achievement • In 2077/78, National Malaria program has achieved 90% reduction in indigenous malaria cases compared to 2071/72.
  29. 29. dengue
  30. 30. dengue • Dengue is an infectious tropical disease caused by the dengue virus (DEN-1-4) & transmitted by the Aedes species mosquito.
  31. 31. Problem statement • The global incidence of dengue has grown dramatically with about half of the world's population now at risk. Although an estimated 100- 400 million infections occur each year, over 80% are generally mild and asymptomatic.
  32. 32. Problem statement- Nepal • Between January to 28 September 2022, a total of 28109 confirmed and suspected dengue cases and 38 confirmed deaths due to dengue have been recorded, affecting all seven provinces of Nepal. • According to the Epidemiology and Disease Control Division (EDCD) of the Ministry of Health and Population, the highest number of new cases in 2022 have been reported in the districts of Kathmandu (n=9528; 33.8%), Lalitpur (n=6548; 23.2%), and Makwanpur (n=2776, 9.8%).
  33. 33. Problem statement- Nepal • In sunsari from 076-1-30 to 076-4-22 2,803 cases without any mortality
  34. 34. agent • Dengue is caused by a virus of the Flaviviridae family and there are four distinct, but closely related, serotypes of the virus that cause dengue (DENV-1, DENV-2, DENV-3 and DENV-4).
  35. 35. vector • Aedes aegypti and Aedes Albopictus
  36. 36. Aedes aegypti • Considered the primary vector of DENV. • It could breed in natural containers such as tree holes but nowadays it has well adapted to urban habitats and breeds mostly in man-made containers including buckets, mud pots, discarded containers and used tyres, thus making dengue an insidious disease in densely populated urban centers.
  37. 37. Aedes aegypti • Ae. aegypti is a day-time feeder; its peak biting periods are early in the morning and in the evening before sunset. • Once a female has laid her eggs, these eggs can remain viable for several months in dry condition, and will hatch when they are in contact with water.
  38. 38. Aedes ALBOpictus • A secondary dengue vector. • It favors breeding sites close to dense vegetation including plantations which is linked to increased risk of exposure for rural workers. • Similar to Ae. aegypti, Ae. albopictus is also a day biter
  39. 39. reserviour man together with the vector acts as reservoir also because the virus is transmitted transovarially.
  40. 40. transmission Transmission through mosquito bite Maternal transmission Other transmission modes
  41. 41. Transmission through mosquito bite • The virus is transmitted to humans through the bites of infected female mosquitoes • After feeding on an DENV-infected person, the virus replicates in the mosquito midgut, before it disseminates to secondary tissues, including the salivary glands. The time it takes from ingesting the virus to actual transmission to a new host is termed the extrinsic incubation period (EIP). The EIP takes about 8-12.
  42. 42. Maternal transmission The primary mode of transmission of DENV between humans involves mosquito vectors. There is evidence however, of the possibility of maternal transmission (from a pregnant mother to her baby).
  43. 43. Other transmission modes Rare cases of transmission via blood products, organ donation and transfusions have been recorded. Similarly, transovarial transmission of the virus within mosquitoes have also been recorded.
  44. 44. Incubation period 3-14 days, commonly 5-7 days
  45. 45. Clinical features • may be asymptomatic or may cause febrile illness as dengue fever, dengue haemorrhagic fever including dengue shock syndrome.
  46. 46. Clinical features
  47. 47. Un differentiated fever Develop a simple fever indistinguishable from other viral infection • Maculo papular rash may accompany fever • Gastrointestinal symptoms are common.
  48. 48. Classical dengue Fever The onset is sudden, with chills and high fever • Intense headache • Muscle and joint pains. • Within 24 hour retro orbital pain, particularly on eye movements or eye pressure • Photophobia • extreme weakness, anorexia, abdominal tenderness, sore throat • The skin eruptions appear in 80% of cases
  49. 49. Dengue haemorrhagic fever • Headache, high fever (lasting 2-7 days) • Rash, and evidence of hemorrhage in the body (Petechiae) • Bleeding in the nose or gums • Black stools, or easy bruising are all possible signs of hemorrhage. • Life-threatening or even fatal
  50. 50. Dengue Shock syndrome As dengue vascular permeability progresses, hypervolemia worsens and results in shock. Criteria: – Tachycardia, cool extremities, delayed capillary refill, weak pulse, lethargy – Hypotension – Pulse pressure ≤ 20 mm Hg
  51. 51. diagnosis • Reverse transcriptase–polymerase chain reaction (RT–PCR) detects the virus directly and is the gold standard; it can be used in the first days after infection. • Rapid diagnostic tests are also available, which test for a protein produced by the virus called NS1. • Serological methods can be used to confirm recent (within the previous 3 months) or past infection.
  52. 52. management • No specific antiviral treatment for the DENV infection. • Most patients recover without complication. • Symptomatic treatment • Management of dengue fever: – Encourage intake of oral rehydration (ORS), fruit juice and other fluids. – Tab. Paracetamol for fever
  53. 53. management Management of DHF • Febrile phase is treated same as dengue fever • IV fluid therapy- crystalloid and colloid • Blood transfusion • Management of Dengue Shock Syndrome • Oxygen therapy • Baseline investigations • IV fluid- dextran, haemacele • Whole blood transfusion/platelet transfusion
  54. 54. Control Measures Mosquito control • In late 2015 and early 2016, the first dengue vaccine, Dengvaxia (CYD-TDV) by Sanofi Pasteur, was registered in several countries for use in individuals 9-45 years of age living in endemic areas. Vaccination
  55. 55. Japanese Encephalitis
  56. 56. introduction • Japanese encephalitis (JE) is a mosquito-borne encephalitis caused by a group B arbovirus (Flavivirus) and transmitted by culicine mosquitoes. • It is a zoonotic disease, i.e., infecting mainly animals and incidentally man.
  57. 57. Problem statement • JE is the main cause of viral encephalitis in many countries of Asia with an estimated 68 000 clinical cases every year. • 24 countries in the WHO South-East Asia and Western Pacific regions have endemic JEV transmission, exposing more than 3 billion people to risks of infection
  58. 58. Problem statement • Although symptomatic Japanese encephalitis (JE) is rare, the case- fatality rate among those with encephalitis can be as high as 30%. • Permanent neurologicol psychiatric sequelae can occur in 30%–50% of those with encephalitis.
  59. 59. Epidemiological features HOST FACTOR: • Reservoir – Pigs, bats, ardeid birds • Incidental hosts –humans INCUBATION PERIOD: -5 to 15 day
  60. 60. transmission Transmitted by culex mosquitoes • The basic cycles of transmission are : – Pig —> Mosquito —> Man – The Ardeid bird —» Mosquito —> Ardeid bird
  61. 61. Transmission cycle
  62. 62. Clinical features Prodromal stage Acute encephalitic stage Late stage and sequelae
  63. 63. Prodromal stage • Fever • Headache • GI disturbances • Lethargy and malaise • The duration of this stage is usually 1-6 days.
  64. 64. Acute encephalitic stage • Fever 38-40.7 degree C • Nuchal rigidity • Focal CNS signs • Raised ICP • Difficulty of speech • Dystonia • Ocular paralysis • Altered sensorium progressing to coma
  65. 65. Late stage and sequelae Characterized by the persistence signs of CNS injury such as: • Mental impairment • Epilepsy, abnormal movements • Speech impairment
  66. 66. diagnosis History • CSF analysis: CSF protein may be elevated • Serological tests: detect antibodies (IgM) • ELISA • Virus culture from blood or CSF: rarely done
  67. 67. Treatment • No specific treatment • Supportive care
  68. 68. treatment Treatment is supportive to relieve symptoms and stabilize the patient. • Oxygenation • Suctioning • IV Fluids and Mannitol • Correction of blood sugar • Anti-convulsant • Antipyretics
  69. 69. Prevention
  70. 70. vaccination JE is endemic in the Terai, with maximum number of cases occurring in the western districts of Banke, Kanchanpur and Kailali. JE immunization with CD-JEVAX at 1 year of age is included in the national immunization program of Nepal with excellent results.
  71. 71. Vector control • Elimination of mosquito breeding areas • Adult and larvae control • Cover tightly all water containers, wells and water storage tanks • Use of mosquito nets, insecticides or coil incenses to repel mosquitoes
  72. 72. Nursing consideration As a community Health Nurse: – Assess the immunization status – Educate people regarding vaccination – Encourage people for adopting preventive measures – Promote early diagnosis and treatment.
  73. 73. Lymphatic filariases
  74. 74. introduction • The term "lymphatic filariasis" covers infection with three closely related nematode worms -Wuchereria bancrofti, B. malayi and B. timori. • Lymphatic filariasis impairs the lymphatic system and can lead to the abnormal enlargement of body parts, causing pain, severe disability and social stigma. • All three infections are transmitted to man by the bites of infective mosquitoes.
  75. 75. Problem statement • 51 million people were infected as of 2018, a 74% decline since the start of WHO’s Global Programme to Eliminate Lymphatic Filariasis in 2000.
  76. 76. Problem statement • Nepal is one of the 73 countries listed by WHO as being endemic for LF. • Nepal conducted LF mapping in 2001 and 2005 and remapping in 2012 by using ICT (Immuno chromatography Test), which revealed 13% average prevalence of LF infection in the country, ranging from <1% to 39%.
  77. 77. Problem statement • The LF mapping completed in 2005 by using ICT (Immunochromatograhy) card revealed that 60 out of 75 districts as endemic for lymphatic filariasis in the country. • Wuchereria bancrofti is the only recorded parasite in Nepal.
  78. 78. The EDCD formulated a National Plan of Action for the Elimination of Lymphatic Filariasis in Nepal (2003–2020) by establishing a National Task Force. The division initiated mass drug administration (MDA) in Parsa district in 2003, which was scaled up to all endemic districts by 2069/70 (2013).
  79. 79. agent • Wuchereria bancrofti, Brugia malayi, B.timori are the worms causing lymphatic filariasis.
  80. 80. reservoir • The main reservoir is man, who harbours microfilariae in the blood.
  81. 81. Host factors (a) AGE: All ages are susceptible to infection (b) SEX : In most endemic areas the rate is higher in men. (c) MIGRATION : The movement of people from one place to another has led to the extension of filariasis into areas previously non-endemic.
  82. 82. Host factors d) IMMUNITY : Man may develop resistance to infection only after many years of exposure. (e) SOCIAL FACTORS : Lymphatic filariasis is often associated with urbanization, industrialization, migration of people, illiteracy, poverty and poor sanitation.
  83. 83. Mode of transmisson • Filariasis is transmitted by the bite of infected vector mosquitoes. • The parasite is deposited near the site of puncture. • It passes through the punctured skin or may penetrate the skin on its own and finally reach the lymphatic system.
  84. 84. Incubation period • The incubation period is about 8 to 16 months. This period may however be longer.
  85. 85. Clinical features • • Eosinophilic lung indicated by eosinophilia, chronic bronchitis and asthma. Allergic • Acute (such as lymphangitis of the legs and genitals) and chronic (such as lymphadenitis in inguinal and femoral regions) Inflammatory • Soft edematous swelling due to blockage of lymphatics followed by fibrotic changes give rise to the picture of elephantiasis. • Soft or hard swelling of testes, legs and feet are common. Sometimes arms, breasts, vulva and penis are also involved. Obstructional
  86. 86. Preventive and control measures 1. Mass Chemotherapy 2. Mosquito Control
  87. 87. Mass chemotherapy • Annual Mass Drug Administration(MDA) of single doses of Albendazole plus Diethyalcarbamazine (DEC) is being implemented, treating the entire at-risk population. • MDA is being continued for 6 years or more to reduce the density of microfilariae circulating in the blood of infected individuals to levels that will prevent mosquito vector from transmitting infection.
  88. 88. Mass chemotherapy • Objective of MDA is to reduce the prevalence of the infection in the entire community • The MDA should have greater than 65% epidemiological coverage (proportion of individuals treated in a district) at each round.
  89. 89. Mass chemotherapy • From this year, triple drug regimen (including Ivermectin) has been introduced in Nepal. • This regimen is more effective in clearing microfilaria faster than DA MDA.
  90. 90. kalazar
  91. 91. Kalazar Visceral leishmaniasis or Kala-azar is a vector-borne disease by the protozoan parasite Leishmania donovani and transmitted by the sandfly, Phlebotomus argentipes.
  92. 92. introduction There are 3 main forms of leishmaniases: • Visceral (the most serious form because it is almost always fatal without treatment), • Cutaneous (the most common, usually causing skin ulcers) • Mucocutaneous (affecting mouth, nose and throat).
  93. 93. epidemiology  An estimated 700 000 to 1 million new cases occur annually.  Only a small fraction of those infected by parasites causing leishmaniasis will eventually develop the disease.
  94. 94. Epidemiology in nepal • National program initially identified 12 districts as kala azar endemic districts. • 6 other districts were included in the list in 2016 because sporadic cases were consistently being reported by these 6 districts. • Currently 18 districts are considered endemic.
  95. 95. Epidemiology in nepal
  96. 96. Agent factor • The leishmania are intracellular parasites. • Leishmania donovani →Kala-azar (VL) • L. tropica → cutaneous leishmaniasis • L. braziliensis → muco-cutaneous leishmaniasis. But visceral forms may produce cutaneous lesions, and cutaneous forms may visceralize.
  97. 97. Reservoir of infection • There is a variety of animal reservoirs, e.g., dogs, jackals, foxes, rodents and other mammals
  98. 98. Host factors • Kala-azar can occur in all age groups. • Males are affected twice as often as females. • Migration from endemic to non-endemic area. • Socio-economic status • Occupation: People who work in various farming practices, forestry, and fishing have a great risk of being bitten by sand flies.
  99. 99. transmission • Kala-azar is transmitted from person to person by the bite of the female phlebotomine sandfly. • Transmission of kala-azar has also been recorded by blood transfusion, and is also possible by contaminated syringes and needles.
  100. 100. Incubation period • The incubation period in man is quite variable, generally 1 to 4 months; range is 10 days to 2 years.
  101. 101. Clinical features Kala-azar (VL) : Classical features: – fever, splenomegaly and hepatomegaly accompanied by anaemia and weight-loss Darkening of the skin (face, hands, feet and abdomen) Lymphadenopathy (uncommon)
  102. 102. Clinical features Muco-cutaneous leishmaniasis • Ulcers similar to the oriental sore (CL) appear around the margins of mouth and nose. • It can mutilate the face so badly that victims may become social outcasts.
  103. 103. diagnosis Clinical Examination Laboratory Examination • Haematological findings: leucopenia, anaemia, raised ESR, • Serological tests: DAT, rk39 dipstick test, • Leishmanin (Montenegro) test
  104. 104. treatment Liposomal Amphotericin B has been introduced in Nepal since 2015 with support from WHO. The national program recommends the use of the following drugs for Kalazar treatment:
  105. 105. treatment • Liposomal amphotericin B infusion (15 mg/Kg in 3 doses or single dose of 10 mg/Kg). OR • Combination therapy regimens: • (i) Miltefosine + Paromomycin and • (ii) L-AmB (5mg/Kg on D1) + Paromomycin (D2-D11). • In children (< 5 years), pregnant and breast feeding women and women of child bearing age group, the preferred regimens will be L- AmB or combination of L-AmB + Paromomycin
  106. 106. Vector control strategies 1. Anti-adult Measures Residual spraying Space application Individual protection
  107. 107. Vector control strategies 2. Anti-larval measures: Larvicides Source Reduction Integrated control
  108. 108. Anti-adult measures (i) Residual spraying : The spraying of the indoor surfaces of houses with residual insecticides (e.g., DDT, malathion, fenitrothion) is still the most effective measure to kill the adult mosquito. It has been observed that discontinuation of spraying has very often led to the resurgence of malaria. This implies that spraying once applied may need to be continued for an indefinite period. (ii) Space application : This is a major anti-epidemic measure in mosquito-borne diseases. It involves the application of pesticides in the form of fog or mist using special equipment. Outdoor space sprays reduce vector population quickly.
  109. 109. Anti-adult measures iii) Individual protection : Man-vector contact can be reduced by other preventive measures such as the use of repellents, protective clothing, bed-nets· The methods of personal protection are of great value when properly employed.
  110. 110. Anti-larval measures i) Larvicides : With the increase in insecticide resistance, the older methods of mosquito control have now become promising. Some modern larvicides such as temephos which confer long effect with low toxicity are more widely used. ii) Source reduction : Techniques to reduce mosquito breeding sites (often called source reduction) which include draining and flushing of water collections; filling of water logged areas; proper maintenance of water levels and intermittent irrigation in dams and canals . Whenever practicable, measures for the improvement of the environment by the permanent reduction of sources should be instituted.
  111. 111. Anti-larval measures (iii) Integrated control : In order to reduce too much dependance on residual insecticides, increasing emphasis is being put on "integrated" vector control methodology which includes bio environmental and personal protection measure. One of the safest and interesting methods in mosquito control is the use of biological agents that eat or destroy the larvae. Eco-friendly larvivorous fish such as the top water minnow or mosquito fish (Gambusia affinis) or the common guppy (Poecilia reticulate) can be effectively used to control the mosquito population.
  112. 112. References Park, K. (2019). Park`s Textbook of Preventive and Social Medicine. M/s Banarsidas Bhanot publishers. Gupta, MC, Mahajan, BK. (2013). Mahajan and Gupta Textbook of Preventive and Social Medicine. Brothers Medical Publishers (P) Ltd. Annual Report, Department of Health Services 2077/2078 https://edcd.gov.np/
  113. 113. MCQs 1.The Animal that is considered as “amplifier host” of the virus, in Japanese encephaliti is a.Man b.Cattle c.Horse d.Pig
  114. 114. 2. Kala-azar is transmitted by (a) mosquito (b) Housefly (c) ticks (d) Sand fly
  115. 115. 3. How many district are endemic for lymphatic filariasis in Nepal? a. 75 b. 77 c. 60 d. 50
  116. 116. 4. Which mosquito species are primarily responsible for Dengue fever? a.Aedes albopictus b.Anopheles c.Aedes aegypti mosquito d.Culex mosquito
  117. 117. 5. Dengue fever incubation period ranges from a.4-12 days b.3-14 days c.14-28 days d. 28-32 days