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Health effects of Flea, Louse, Ticks & Mites

Dr. Ambreen Ansar1

LEARNING OUTCOMESBY THE END OF THE LECTURE STUDENTS SHOULD BE ABLE TO:Identify & differentiate the arthropods of medical importanceexplain briefly taxonomy of arthropods identify the arthropod habitatexplain importance of arthropods Advice a control plan for human arthropod borne infections2

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Causative agents transmitted through arthropods1. Arbovirus infectionsYellow feverDengue feverJapanese B encephalitis2. Rickettsial infections1.Epidemic typhus2. Murine typhus3. Scrub typhus4. African tick typhus5. Q fever3. Bacterial infectionsPlagueTick-borne relapsing feverLouse-borne relapsing fever4. Protozoal infectionMalariaAfrican trypanosomiasisSouth American trypanosomiasisLeishmaniasis5. Helmenthic infectionsFilariasisLoasisOnchocerciasis

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Diseases Causing agents transmitted through arthropodsDiseaseAgentsVectors 1.Epidemic typhus2. Murine typhus3. Scrub typhus

4. Indian tick typhus5. Q feverR. prowazekiiR. TyphiR. orientia tsutsugamushiR. coroniiCoxiella burnettiLouseFleaLarval Trombiculid miteTickTicks PlagueTick-borne relapsing feverLouse-borne relapsing fever3. Bacterial infectionsFlea Tick

Louse 1. Scabies Direct vector being the causative agentItch mite

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Diseases transmitted by Flea & LouseFLEAPlagueFlea borne /Murine/Endemic typhusChiggerosisHymenolepis diminutaLOUSEEpidemic typhusRelapsing feverTrench feverDermatitis 8

Diseases transmitted by ticksHard ticksTick typhusViral encephalitisViral feversViral hemorrhagic feversTularemia Tick paralysisHuman babesiosis

Soft ticksQ feverRelapsing fever

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Diseases transmitted by mitesTrombiculid miteItch mite/sarcoptes scabeii/ Acarus scabeiiScrub typhusScabies 11

HabitatsLouse Flea Human lice are known to live throughout the hair, skin, and body parts of humans. Since they survive from the blood of their host, they tend to live on the hair, or even clothing of the person.Fleas are always found among the feathers or hair or within the nests of animals. The main introduced species are the cat flea, the dog flea and the rat flea (Xenopsylla cheopis). The most heavily parasitized group of mammals are the rodents (e.g., rats, mice, squirrels).12

Habitats Ticks Mites Wooded areasTall brush/grassUnder plants/leaves to prevent dehydration cut/raked lawns or sports fieldsUnder ground cover (plants) in yard Around stone walls and woodpiles where mice & other small mammals live

Many live freely in the soil or water, but there are also a large number of species that live asparasiteson plants, animals, and some that feed onmold.13

A 45-year-old, previously healthy man presented with a 2-day history of increasing fever, myalgia, rigors, headache, and weakness. The patient had a history of camping and sleeping on the ground. The patient had history of rodent exposure.Physical examination revealed an acutely ill man with a blood pressure of 85/57 mm Hg, a respiratory rate of 26 breaths/min, a heart rate of 117 beats/min, and a temperature of 38.5C. He had acrocyanosis, severe muscle pain, and a purpuric rash with evolving gangrene of the extremities . Skin lesions, lymphadenopathy, and pneumonia were not present. His abdomen was diffusely tender, without peritoneal signs. In the ensuing days, he had progressive gangrene of the fingers, toes, ears, and nose.

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A 45-year-old, previously healthy man presented with a 2-day history of increasing fever, myalgia, rigors, headache, and weakness. The patient had a history of camping and sleeping on the ground. The patient had history of rodent exposure.Physical examination revealed an acutely ill man with a blood pressure of 85/57 mm Hg, a respiratory rate of 26 breaths/min, a heart rate of 117 beats/min, and a temperature of 38.5C. He had acrocyanosis, severe muscle pain, and a purpuric rash with evolving gangrene of the extremities . Skin lesions, lymphadenopathy, and pneumonia were not present. His abdomen was diffusely tender, without peritoneal signs. In the ensuing days, he had progressive gangrene of the fingers, toes, ears, and nose.

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Early gangrenous changes in the feet of a patient with septicemic plague.

T. Kuberski et al. Clin Infect Dis. 2003;36:521-523 2003 by the Infectious Diseases Society of America16

Early gangrenous changes in the feet of a patient with septicemic plague

Another caseA 25-year-old Indian rancher was admitted because of a two-day history of headache, chills, and fever (40C). The day before admission, he began vomiting. The day of admission, an orange-sized swelling in the left axilla was noted. A lymph-node aspirate and a smear of peripheral blood were reported to contain gram-positive cocci, often in pairs.Inthe 2 weeks prior to becoming ill, the patient had trapped, killed, and skinned 3 foxes, 4 coyotes, and 1bobcat. The patient had cut his left hand shortly before skinning the bobcat.17

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CHARACTERISTICS OF PLAGUEAgent HostOr occupations involvedEnvironment Mode of TransmissionOr vectorIncubation period

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PLAGUECausative agent: Yersinia pestisDistribution :Although the number of cases of plague have gradually declined, foci of the disease still exist in the Indian sub continental, China, South Asia, Africa, South America and Middle East.

Currently it is not existing in Pakistan.20

Agent factors:Agent: It is a gram negative, non motile cocco-bacillus.Reservoir: Wild rodents (e.g. field mice, skunks, gerbils and other small animals.Sources of infection: Infected rodents and fleas Cases of Pneumonic Plague

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Host factors:Age and sex: All ages and both sexes are susceptible.Human activities : Man may come into contact with natural foci in the course of hunting, grazing, cultivation, harvesting and construction activities.Movement of People: Plague is associated with movement of people and cargo by sea or land. Immunity: Man has no natural immunity. Immunity after recovery is relative.

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Environmental factors:Season: Plague season starts from September till May.Temperature and Humidity: A mean temperature of 20 - 25C and relative humidity of 60% and above are considered favorable for the spread of Plague.Human dwellings: Rats infested dwelling.Vectors: Rat flea (Xenopsilla cheopsis), X. astia, X. brasiliensis & Pulex irritans23

Fleas are wingless insects, 1/16 to 1/8-inch (1.5 to 3.3 mm) long, that are agile, usually dark colored.

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Period of communicabilityPneumonic plague is very communicable from person to person Bubonic plague is directly communicable only if there is terminal plague pneumonia. Fleas often remain infective for life. There is no trans-ovarian transmission.

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Mode of transmission:Most frequently contracted from the bite of an infected flea.Occasionally by direct contact with the tissues of an infected animal.By droplet infection from cases of pneumonic plague.

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Incubation periodBubonic plague2 - 7 daysSepticemic plague2 7 daysPneumonic plague1 3 days

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Clinical manifestationsThere are 4 recognized clinical forms:Bubonic plague: In this patient has sudden onset of fever, restlessness, prostration and Later the appearance of a painful bubo, which is an inflamed lymph node commonly of the inguinal region.Vesicular and pustular skin lesions many develop.

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Septicemic plague30

Pneumonic plague: It is the most deadly form. Patients develops fever, cough, hemoptysis. Sputum contain Y.Pestis in large numbers. Death occurs in 2-4days after onset.Sylvatic plague: It is the name given to plague that remains endemic in rodents in jungle. Man is affected accidentally while hunting.

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Laboratory diagnosis:Staining: It is important to prepare smears of the clinical material (e.g. bubo fluid, sputum) which should be fixed with alcohol and then stained with Giemsas or waysons stain to demonstrate bipolar bacilli in the specimen.Culture: Of organism from blood taken from patients.Serology: Acute and convalescent specimens of blood sera should be collected for antibody studies.32

Epidemiological triad of Plague33

PREVENTION AND CONTROL OF PLAGUEStrategiesActions 1. Targeting the agentCasesEND IT!!Carriers CT2. Targeting the vectorThe Flea DDT, BHC orCarbaryl, Malathion3. Targeting the hostVaccination Haffkine ; killed Plague vaccine4. Targeting the environmentThe rodentsHousing, sanitation, quality of lifeSurveillance of endemic areasHuman & rodent sME3S

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Prevention and controlA. Control of cases: (targeting the agent)Early diagnosis:Diagnosis of plague can be made readily on clinical grounds e.g. acute fever and painful lymph node.Rat falls (dead rats) provide a useful warning of a possible outbreak.Notification: If a human or rodents case is diagnosed health authorities must be notified promptly.35

Control of cases: (targeting the agent)Isolation : It is recommended whenever possible. Treatment : It should be started without waiting for confirmation of the disease.The drug of choice is streptomycin.Tetracycline is an alternative drug.Disinfection: Of sputum discharges and articles soiled by the patient. Dead bodies should be handled with aseptic precautions.

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B. Control of cases: (Carriers) (targeting the agent)Chemoprophylaxis : It is a valuable preventive measure. It should be offered to all plague contacts & suspected carriers. The drug of choice is tetracycline.

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38Food for thought!

How can you identify the carriers of plague?

1. cases of subclinical Plague2. untreated infections3. Asymptomatic pharyngeal infection in carriers

Control of Fleas (targeting the vector) The most effective method to break the chain of transmission (rodent-flea-man) is the destruction of rat fleas by the proper application of an effective insecticide.

In general DDT and BHC should be used.

In areas where resistance to one or both of these insecticides dust of carbaryl (2%) or malathion (5%) should prove effective.39

Flea indices a warning for imminent Plague outbreakUseful measurement of the density of fleas helpful in evaluating the effectiveness of a spraying programme.Total flea indexCheopsis indexSpecific percentage of fleasBurrow index40

What is blocked and partially blocked flea?Can it act as transmitter of the disease?

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Control of Rodents(targeting the environment) Continuous mass destruction of rodents is an important plague preventive measure. Control of rodents should be based on improvement of general sanitation, housing and quality of life.

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Surveillance(targeting the environment)Surveillance should cover all aspects of rodents and human plague for example:Microbiology, Serology, Entomology, Epidemiology and Ecology. On the basis of information provided by surveillance, effective control measures must be established.

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What should a Plague surveillance team do & look for?Detailed study of all cases of plague.Keep complete record of each case.Isolate strains of Y. pestis for detailed biochemical analysis.Serological survey of target population to identify untreated infections and asymptomatic pharyngeal carriers.Keep an eye on changes in human social and economic activities and rodent population.44

Keep a watch on containerized cargoes of grains and other food crops.Cooperate and coordinate with adjacent countries.Special attention to areas near sea ports and airports.45

Vaccination(targeting/upgrading the host)Immunization with plague vaccine is a valuable preventive measure. Vaccination should be carried out at least a week before an anticipated outbreak. Haffkine ; killed plague vaccineIt should be given subcutaneously in 2 doses of 0.5 and 1 ml at interval of 7-14 days.Immunity starts 5-7 days after inoculation and remains for 6 months. At risk population should be vaccinated biannually.

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Dosage of plague vaccine

47Age and genderPrimary inoculationBooster doses1st dose2nd doseAdult males1.0ml1.5ml1.0mlAdult females0.75ml1.0ml0.75mlChildren 1-4 years0.2mlDouble the first doseSame as the first dose5-10 years0.3ml11-16 years0.4mlInfants under 6 months of ageNot immunized

Health Education(targeting/upgrading the host)It is an essential part of any plague control programme.Education should aim at providing the public with the facts about plague and at enlisting their cooperation.Emphasis must be placed on the need for the prompt reporting of dead rats and suspected human cases.Medical practitioners should keep plague in mind differential diagnosis of any case of fever with lymphadenopathy.

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If these are the types of Plagues identify each and name it.49

TYPHUS FEVER They are caused by Rickettsia type of organism, which are coccobacilli. They are transmitted to man by an insect or other arthropods like tick or mite. They are classified according to their arthropod vectors into 4 principal diseases.Louse borne or epidemic typhusFlea born or Murine typhusTick born or Rocky Mountain spotted feverMite born or Scrub typhus (tsutsugamushi disease)50

DiseasesRicckettsial agentsInsect vectorsMammallion vectorsnemonicsTyphus group1. Epidemic typhusR. ProwazekiLouseHumansEPL2. Murine typhusR. TyphiFleaRodentsMTF3. Scrub typhusR. TsutsugamushiMiteRodents STsMSpotted fever group1. Indian tick typhusR. ConoriiTickRodents, dogsTCT2. Rocky mountain spotted feverR. RicketsiiTickRodents, dogs3. Rickettsial poxR. AkariMiteMiceothers1. Q feverC. BurnettiNilCattle, sheep, goats2. Trench feverRochalimaea quintanaLousehumans

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Differentiating symptoms of Typhus feversSign & symptoms of various Typhus feversEpidemic typhus/LouseMurine typhus/ Endemic/ Flea-borneScrub typhus/Mite-borneTick TyphusCommon to all: Headache, fever, chills, rashhigh fever (above 104 degrees Fahrenheit)Symptoms similar to louse-borne but milder and rarely fatal.Generalized swollen lymph nodesFever which persist for 2-3 weeksMacular rash that begins on the back or chest and spreadsred lesion or sore on the skin at the site of the biteMaculopapular rash appears first on extremetiesconfusionTirednessstupor and seeming out of touch with realitycoughlow blood pressure (hypotension)Punched out ulcer covered with blackened scab (eschar)Lesion or eschar at the site of biteeye sensitivity to bright lightssevere muscle pain

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LOUSE TYPHUSIt is the only fever in typhus group which appears in epidemic form. Causative organism : Rickettsia prowazeki Vector: Pediculus humanus capitis

53The headlouse(Pediculus humanus capitis) is an obligate ectoparasite , a wingless insects spending its entire life on the human scalp and feeding exclusively on human blood.

Host factors: Following factors favors its spread OvercrowdingPersonal unhygienic conditionMalnutritionLouse infestationIncubation period : 10 -14 daysClinical features: The onset of the disease is sudden in which patient develops fever with chills, headache which usually last for two weeks. The patient also develops rash which initially is papular later on it becomes macular and petechial rash which extends to arms and legs.Diagnosis: It is made by serological test called Weil Felix reaction.54

55Along withRickettsia prowazekiiandBartonella quintana,Borrelia recurrentisis one of three pathogens of which thebody louse(Pediculus humanus humanus) is a vector

Head lice and petechial rash caused by Louse bite56

ControlPreventive measures:Apply 10% DDT powder to clothes and bodies of person who are infected with lice.Living conditions should be improved. Frequent baths and washing of clothes should be encouraged.

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Control of infected persons, contacts and environment:Notify to local health authorityIsolation is not required after the patient has been delousedConcurrent disinfection: Apply insecticide powder to clothes and bedding of patient and contacts.Terminal disinfection: If death occurs before delousing, thorough application of insecticide to body and clothing.Quarantine : susceptible contacts may be released after applying DDTImmunization of all contacts Treatment of cases with tetracycline or chloremphenicol for 3 4 days.END IT58

Epidemic measures:Delousing : Insecticides should be applied to all contacts.ImmunizationInternational measures:Government should notify WHO Ships aircrafts and land transport arriving from typhus areas are given thorough application of residual insecticides. International travelers from Typhus endemic areas are allowed to enter after application of DDTThose persons entering typhus areas should get themselves vaccinated.59

Tick typhusCausative organism: Rickettsia conoriiReservoir: Wild animals, chiefly rodents and dogs. Tick itself.Mode of transmission: The infection is transmitted by the bite of hard tick known as Dermacentor Andersoni. Contamination of skin with crushed tissues or faeces of an infected ticks. 60

Incubation period: 3 - 7 daysClinical features:It is the mild form of typhus characterized by a black spot at the site of tick bite. The regional lymph nodes enlarge and the body is entirely covered with a maculopapular rash. Fever occur after 3 -7 days of bite. Rash appears first on extremitiesDiagnosis: The weil-felix reaction is usually positive with proteus 0X2.

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Control measures

Avoid infected localities and animals.Toavoid ticks, walk in the center of trails andavoidwalking through tall bushes or other vegetation. Use a repellent with DEET (on skin or clothing) or permethrin (on clothing and gear). Repellents containing 20% or more DEET (N, N-diethyl-m-toluamide) can be applied to the skin and can protect up to several hours.Wear tick proof clothes impregnated with dimethylphthalate in infected areas. 63

Frequent examination of whole body, if found they should be removed with forceps.Vaccination for contacts:2 injections with 10 days apart.Treatment with antibiotics.Health education of people regarding mode of transmission and its prevention.

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How to Prevent tick bite65

Murine typhus (flea-born-endemic)Causative organism: Rickettsia TyphiDistribution : World wide appears to be more prevalent in South East Asia.Vector: Rat flea( X. cheopsis)Reservoir : Rattus rattus and Rattus norvegicusMode of transmission:Inoculation into skin of faeces of infected fleas.Inhalation of derived infective faeces.Incubation period : 6 14 days66

Endemic or flea borne typhus

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Period of communicability: not communicable from man to man.Susceptibility: is general Immunity: One attack of murine typhus gives immunity which is not always permanent Clinical features : Resembles epidemic typhus but milder in intensity.Diagnosis : Weil felix reaction is usually positive with proteus OX-19 in 2nd week.Methods of control:Preventive measures: Apply DDT powder to rat runs and burrows to kill rat fleas.

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Control of Infected persons, contacts and environment:Notification to local health authority No need of isolationTreatment of the casesEpidemic measures: Wide spread use of DDT markedly reduces the flea index of rats. 69

Murine typhusa patient presents with persistent fever of 5 days' duration without explanation, there is a history of exposure to cats infested with wingless dark coloured insects approx 2-3mm long. Maculopapaular rash, hypotension and stupor is positive on examination. No bite marks are visible on the body. 70

Scrub or Mite typhusTsutsugamushi diseaseCausative organism: Rickettsia orientalist or R.tsutsugamushi.Vector : The disease is transmitted to man by larval mites.Mode of transmission: by the bite of infected larval mites. It is not directly transmitted from persons to persons. Incubation period : 6 -14 days71

Clinical features: Sudden onset of fever with chills, conjunctional infection and lymphadenopathy. Cutaneous rash appears on the 5th day.Diagnosis : The causative organism can be recovered from the blood during the febrile period. A positive weil felix reaction is usually obtained with proteus OXK.72

Methods of controlPreventive measures:Avoid infected localitiesInsecticides should be applied on individual clothes and body if he has to work in infected areas.No need of isolation and quarantineNo effective vaccine is available but prophylacticaly chloramphenicol can be taken..

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Treatment : Wash bite site with soap and waterApply ice pack to bite area to reduce swelling, itching and pain.In children trim fingernails to prevent further injury from scratching.Topical Benzocaine or lidocaine can be use for 7 days max to relieve itching and irritation.Calamine, oral antihistamine and topical hydrocortisone may be beneficial.Broad spectrum antibiotics are very effective in treating scrub typhus74

Eschar after the bite of mite

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77Trombiculid MiteFleaLouseHard tick

78Clinical presentations of Typhus fevers vary with the causative agent and patient; however, common symptoms that typically develop within 12 weeks of infection include fever, headache, malaise, rash, nausea, and vomiting. Many rickettsioses are accompanied by a maculopapular, vesicular, or petechial rash or sometimes an eschar at the site of the tick bite. Scrub typhus should be suspected in patients with a fever, headache, and myalgia after recent travel to Asia; eschar, lymphadenopathy, cough, and encephalitis may be present. Patients with murine or epidemic typhus usually present with a severe but nonspecific febrile illness, and approximately half will also present with a rash.

Relapsing feversRelapsing fever is a recurring febrile disease transmitted to humans by ticks (endemic form) and by body lice (epidemic form). It is caused by several differentBorreliaspecies.79

Rash of ScabiesScabies is a contagious skin disease marked by itching and small raised red spots, caused by the itch mite.80

ScabiesLife cycle from egg to adult form takes10 to 15 days.Adult mite live for 1 to 2 months. Mode of spread:Close contact (house hold infection)Contaminated Clothes.

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Site of Lesions:The disease classically affectsHands and wrist 63%Extension aspect of elbow 10.9%Axilla, buttocks, lower abdomenPalm in infants are all common sites of infestation.82

Control of ScabiesEssential to treat all the members of family whether or not they appears to be infested.Before start of treatment patient is given a god scrub with soap and hot water.Benzyl benzoate 25% is an effective sarcopticide. It should be applied with a paint brush or shaving brush to every inch of the body below the chin including the sole of feet and allowed to dry. 83

Application should be repeated after 12 hours. Other chemicals which are effective:HCH: 0.5 to 1.0% strength of gamma HCH (lindane) in coconut oil or any vegetable oil. Lindane is rarely used because of its side effects.Tetmoslol 5% of its solution is effective, there daily application are recommended.Sulphur ointment: 2.5 to 10% daily for 4 days is a cheap remedy.84

Before treatment,wash underwear, towels, and sleepwearin hot water. Items that cannot be washed or dry-cleaned can be decontaminated by removing from any body contact for at least 72 hours.Vacuum the carpets and upholstered furniture.Use calamine lotion and soak in a cool bath to ease itching.Take an oral antihistamine85

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