Community Health Nursing I: Epidemiology of Communicable Diseases

Communicable Diseases

Malaria

• Causative agent: Plasmodium falciparum, vivax, ovale, malariae (Protozoa)
• Mode of transmission: Vector (female Anopheles mosquito)
• Incubation period: 7 days or longer
• Signs and symptoms: Recurrent fever, chills, profuse sweating, malaise, anemia
• Laboratory/diagnostic examination: Blood smear, history of having been in a malaria-endemic area
• Treatment: Chloroquine phosphate, Sulfadoxine, Primaquine, Pyrimethamine, Quinine sulfate, Tetracycline HCl
• Prevention and control: Mosquito control, chemical methods, biological methods, zooprophylaxis, environmental methods

Filariasis

• Causative agent: Wuchereria bancrofti, Brugia malayi
• Mode of transmission: Bite of mosquito
• Incubation period: 8 to 16 months
• Signs and symptoms: Chills, fever, myalgia, lymphangitis with gradual thickening of the skin (commonly affecting limbs, scrotum) resulting in elephantiasis and hydrocele
• Laboratory/diagnostic examination: Circulating filarial antigen (CFA) - finger prick
• Treatment: Diethylcarbamazine citrate (Hetrazan)
• Prevention and control: Sanitary disposal of feces, practice hand washing, avoid feces, fomites, flies, food, and fluids (5 Fs) that carry the infection

Typhoid Fever

• Causative agent: Salmonella typhosa
• Mode of transmission: Ingestion of contaminated food or water with feces or urine of infected individuals
• Incubation period: 7 to 14 days
• Signs and symptoms: Prodromal (headache, fever, ancrexia, lethargy, diarrhea, vomiting, abdominal pain), Fastigial (Ladder-like curve of temperature, rose spots on trunks, splenomegaly), Defervescence (fever gradually subsides, onset of complications)
• Laboratory/diagnostic examination: Typhidot test
• Treatment: Chloramphenicol, Co-trimoxazole
• Prevention and control: Safe water supply, handwashing, increase fluid intake, administer oral rehydrating solutions, monitor intake and output, and observe for signs of dehydration

Cholera

• Causative agent: Vibrio cholerae (El Tor)
• Mode of transmission: Ingestion of contaminated food, water, or milk
• Incubation period: 1 to 3 days
• Signs and symptoms: Rapid explosive watery stool, vomiting
• Laboratory/diagnostic examination: Stool Exam
• Treatment: Tetracycline, Furazolidone
• Prevention and control: Boiling and chlorination of water, sanitary disposal of human waste, administer vaccine per orem

Measles

• Causative agent: Morbili virus (Paramyxoviridae)
• Mode of transmission: Airborne
• Incubation period: 8 to 20 days
• Signs and symptoms: Acute onset of fever, rhinitis, conjunctivitis, bronchitis, excessive lacrimation, Koplik's spots (clustered white lesions) on the buccal mucosa, stomatitis, maculo papular rashes
• Laboratory/diagnostic examination: Tissue culture of naso-pharyngeal secretions and serological testing
• Treatment: Supportive care, antibiotic if with complications
• Prevention and control: Administer measles vaccine (MMR vaccine), isolation, increase fluid intake, provide eye, nasal, and oral care

Mumps

• Causative agent: Mumps virus (Paramyxovirus)
• Mode of transmission: Airborne or droplets, or direct contact with saliva or infected person
• Incubation period: 16 to 18 days
• Signs and symptoms: Acute onset of fever, painful swelling of the salivary or parotid glands, headache, complications range from meningo-encephalitis to permanent hearing impairment and orchitis
• Laboratory/diagnostic examination: Serological testing
• Treatment: Supportive care
• Prevention and control: Mumps vaccine (MMR vaccine), strict isolation, handwashing, use of mask when handling patient, terminal disinfection, provide oral care

Rubella or German Measles

• Causative agent: Rubella togaviridae virus
• Mode of transmission: Droplet and direct contact with nasopharyngeal secretions of infected person
• Incubation period: 10 to 21 days
• Signs and symptoms: Fever, headache, malaise, maculopapular rash, enlarged post auricular occipital and posterior cervical lymphadenopathy, sore throat, rhinitis, conjunctivitis, bronchitis, forchheimer's spot (small red spots) on the soft palate
• Laboratory/diagnostic examination: Serological testing
• Treatment: Supportive care
• Prevention and control: Rubella vaccine (MMR vaccine), isolation, handwashing, trim fingernails, daily bath

Poliomyelitis

• Causative agent: Legio debilitans or polio virus
• Mode of transmission: Fecal-oral, droplet
• Incubation period: 7 to 21 days
• Signs and symptoms: Abortive (fever, sore throat, low-lumbar backache/cervical stiffness on anteflexion of spine), Non-paralytic (recurrence of fever, poker spine, tightness, and spasm of hamstring hypersensitiveness of the skin, deep reflexes are exaggerated), Paralytic (with paralysis depending on part affected)
• Laboratory/diagnostic examination: Blood and throat culture, stool examination, lumbar tap
• Treatment: Symptomatic and supportive
• Prevention and control: Proper disposal of fecal waste, handwashing, proper preparation of food, immunization of oral polio vaccine

Enterobiasis

• Causative agent: Enterobius vermicularis or the human pinworm or seatworm
• Mode of transmission: Vehicle-ingestion of contaminated food
• Incubation period: 4 to 6 hours
• Signs and symptoms: Perianal itching, disturbed sleep, and nervousness
• Laboratory/diagnostic examination: Scotch tape swab test in the perianal region
• Treatment: Mebendazole single dose repeated at 2nd week for effectivity
• Prevention and control: Personal hygiene, handwashing, keeping fingernails short

Ascariasis

• Causative agent: Ascaris lumbricoides (roundworm)
• Mode of transmission: Fecal-oral
• Incubation period: 8 weeks
• Signs and symptoms: Abdominal pain, and passing out of worms
• Laboratory/diagnostic examination: Stool examination
• Treatment: Mebendazole or Albendazole
• Prevention and control: Proper disposal of feces, avoid using feces as fertilizer, handwashing, and proper washing of vegetables before consumption

Ancylostomiasis

• Causative agent: Ancylostoma duodenale
• Mode of transmission: Contact
• Incubation period: 4 to 6 weeks
• Signs and symptoms: Rash at site of inoculation, enlargement of the abdomen, diarrhea, body weakness
• Laboratory/diagnostic examination: Stool examination
• Treatment: Praziquantel (Biltricide), Oxamniquine for S.mansoni and S.haematobium
• Prevention and control: Proper disposal of feces and urine, proper irrigation of all stagnant bodies of water, prevent exposure to contaminated water, eradication of breeding places of snails, and use of molluscides

Schistosomiasis

• Causative agent: Schistosoma japonicum, S.mansoni, S.haematobium
• Mode of transmission: Contact
• Incubation period: 4 to 6 weeks
• Signs and symptoms: Dermatitis, abdominal pain, anemia, mentally and physically underdeveloped
• Laboratory/diagnostic examination: Stool examination
• Treatment: Mebendazole
• Prevention and control: Avoid walking barefooted, practice personal hygiene, and eradicate breeding places of snails

Zoonoses

• WHO (2019) defines zoonoses as diseases and infections that are naturally transmitted between vertebrate animals and humans
• A zoonotic agent may be a bacterium, a virus, a fungus, or other communicable disease agent### Rabies
• Causative agent: Rhabdovirus
• Mode of transmission: Bite of rabid animal
• Incubation period: 20-90 days for humans, 1 week to 7.5 months for dogs
• Signs and symptoms in dogs: Withdrawal, change in mood, nervousness, apprehension, unusual salivation, paralysis starting on hind legs, death
• Signs and symptoms in humans: Flu-like symptoms, headache, pain and numbness sensation at the site of bite, depression, penile erection or spontaneous ejaculation for males, anxiety, confusion, insomnia, dementia, intense excitement, difficulty in breathing, swallowing, hyrophobia, paralytic-flaccid ascending symmetric paralysis, coma, death
• Laboratory/diagnostic examination: Post-mortem direct fluorescent antibody staining test
• Treatment: Isolate patient, provide care and company, darken room and observe silence, give food if patient is hungry, observe universal precaution, wash hands frequently, remove oral and nasal secretions, dispose contaminated materials, perform terminal disinfection
• Prevention and control: Encourage family to provide care, administer anti-tetanus serum/tetanus anti-toxin and suture if severe wounds, observe dog for 10 days for signs of rabies

Leptospirosis

• Causative agent: Leptospira interrogans (bacteria)
• Mode of transmission: Inoculation into broken skin, mucous membrane or ingestion of contaminated food and water with urine of animals
• Incubation period: 7-13 days
• Vector: Urine of rodents, pet animals, and farm animals
• Signs and symptoms: Sepsis stage (high fever, calf pain, abdominal pain), immune/toxic stage (anicteric stage, icteric stage), convalescence stage (symptoms disappear but relapse may occur 4th-5th weeks)
• Laboratory/diagnostic examination: Blood/urine culture done on the 1st week, Leptospira Agglutination test (LAT) done on the 2nd to 3rd week
• Treatment: NI: Contact isolation, Penicillin or Tetracycline, Doxycycline
• Prevention and control: Laundry and iron soiled clothes, practice personal hygiene, terminal disinfection

Anthrax

• Causative agent: Bacillus anthracis
• Mode of transmission: Cutaneous (skin) anthrax by handling sick animals or contaminated animal wool, hair, hides, or bone meal products, inhalational anthrax by breathing anthrax spores into the lungs/woolsorter's disease, gastrointestinal anthrax by eating meat products containing anthrax
• Incubation period: Varies depending on the mode of transmission
• Signs and symptoms: Skin lesions, throat pain, difficulty swallowing, sepsis, meningitis
• Laboratory/diagnostic examination: Gram staining (+)
• Treatment: Formaldehyde, fluoroquinolones, ciprofloxacin
• Prevention and control: BioThrax vaccine, avoid contact with secretions, practice monogamous sexual contact

Sexually Transmitted Infections (STI)

• 4Cs in Syndromic Case Management for STI: Compliance, Counseling, Contact tracing, Condom use
• Prevention and control: Practice monogamy, sex education, promote condom use to risk individuals to reduce the chance of acquiring the disease

Gonorrhea

• Causative agent: Neisseria gonorrhoeae
• Mode of transmission: Sexual contact
• Incubation period: 2-7 days
• Signs and symptoms: Thick purulent urethral discharge, frequency of urination among females, burning urination among males/females
• Laboratory/diagnostic examination: Culture of specimen in cervix-female, Gram stain-male
• Treatment: Ceftriaxone
• Prevention and control: Practice monogamy, sex education

Syphilis

• Causative agent: Treponema pallidum
• Mode of transmission: Sexual contact
• Incubation period: 10-90 days
• Signs and symptoms: Primary (chancre), secondary (condylomata, throat, mucous patches of the mouth, macupapular rash), tertiary (gumma formation, cardiovascular and nervous system involvement)
• Laboratory/diagnostic examination: Darkfield illumination test, venereal disease research laboratory (VDRL) test, Fluorescent treponemal antibody test
• Treatment: Safe sexual practices, cesarean delivery if lesions are present during late pregnancy
• Prevention and control: Safe sexual practices, cesarean delivery if lesions are present during late pregnancy

Rabies

• Causative agent: Rhabdovirus
• Mode of transmission: Bite of rabid animal
• Incubation period: 20 to 90 days for humans, 1 week to 7.5 months for dogs
• Signs and symptoms: Myalgia, lymphangitis with gradual thickening of the skin, and hydrocele
• Prevention and control: Eradication of vectors, sanitary disposal of feces, practice hand washing, avoid feces, fomites, flies, food, and fluids (5 Fs) that carry the infection, immunization with Rabies vaccine
• Treatment: Post-exposure treatment includes washing the wound with soap and water, administering Anti-tetanus serum/tetanus anti toxin and suture if severe wounds, observing dog for 10 days for signs of rabies

Schistosomiasis

• Causative agents: Schistosoma japonicum, S. mansoni, S. haematobium
• Mode of transmission: Contact with contaminated water, faeces, and urine
• Incubation period: Flu-like symptoms, headache, pain and numbness sensation at the site of bite
• Signs and symptoms: Depression, penile paraesthesia, difficulty swallowing
• Laboratory/diagnostic examination: Circulating filarial antigen (CFA) test, finger prick
• Treatment: Diethylcarbamazine citrate (Hetrazan)
• Prevention and control: Proper disposal of feces and urine, proper irrigation of all stagnant bodies of water, prevention of exposure to contaminated water, eradication of breeding places of snails, use of molluscicides, avoid walking barefooted, and practice personal hygiene

Typhoid Fever

• Causative agent: Salmonella typhi
• Mode of transmission: Fecal-oral route, contaminated food and water
• Incubation period: 10-14 days
• Signs and symptoms: Fever, headache, myalgia, malaise
• Laboratory/diagnostic examination: Stool examination
• Treatment: Mebendazole
• Prevention and control: Sanitary disposal of feces, practice hand washing, avoid feces, fomites, flies, food, and fluids (5 Fs) that carry the infection, immunization with Typhoid vaccine

Haematobium

• Causative agent: Schistosoma haematobium
• Mode of transmission: Contact with contaminated water
• Incubation period: 20 to 90 days
• Signs and symptoms: Myalgia, lymphangitis with gradual thickening of the skin, and hydrocele
• Laboratory/diagnostic examination: Circulating filarial antigen (CFA) test, finger prick
• Treatment: Diethylcarbamazine citrate (Hetrazan)
• Prevention and control: Proper disposal of feces and urine, proper irrigation of all stagnant bodies of water, prevention of exposure to contaminated water, eradication of breeding places of snails, use of molluscicides, avoid walking barefooted, and practice personal hygiene

Zoonoses

• Definition: Diseases and infections that are naturally transmitted between vertebrate animals and humans
• Examples: Rabies, Schistosomiasis, Typhoid Fever

Gonorrhoea

• Causative agent: Neisseria gonorrhoeae
• Mode of transmission: Sexual contact
• Incubation period: 2 to 7 days
• Signs and symptoms: Thick purulent urethral discharge, frequency of urination, burning urination
• Laboratory/diagnostic examination: Culture of specimen in cervix-female, Gram stain-male
• Treatment: Ceftriaxone
• Prevention and control: Practice monogamy, sex education, avoid contact with secretions, use condoms

Syphilis

• Causative agent: Treponema pallidum
• Mode of transmission: Sexual contact
• Incubation period: 10-90 days
• Signs and symptoms: Primary: chancre, Secondary: condylomata, throat, mucous patches of the mouth, macupapular rash, Tertiary: gumma formation, cardiovascular and nervous system involvement
• Laboratory/diagnostic examination: Darkfield illumination test, venereal disease research laboratory (VDRL) test, Fluorescent treponemal antibody test
• Treatment: Penicillin, tetracycline, erythromycin
• Prevention and control: Practice safe sexual practices, test pregnant women, and educate on sexual health

Chlamydia

• Causative agent: Chlamydia trachomatis
• Mode of transmission: Sexual contact, contact with exudates from mucous membranes, childbirth
• Incubation period: 7-14 days
• Signs and symptoms: Urethritis with purulent discharge from anterior urethra (males), mucopurulent cervicitis often asymptomatic (females), endometritis, salphingitis, and pelvic peritonitis
• Laboratory/diagnostic examination: Culture & Nucleic acid amplification test (NAAT) of urine or swab samples
• Treatment: Doxycycline, Azithromycin single dose
• Prevention and control: Practice safe sexual practices, use condoms, and educate on sexual health

Genital Warts

• Causative agent: Human Papilloma Virus (HPV) with 100 types
• Mode of transmission: Direct contact with infected skin and mucous membranes, childbirth
• Incubation period: 2 to 3 months, range 1 to 20 months
• Signs and symptoms: Circumscribed lesions in cervix, vulva, anus, penis, vagina, oropharynx
• Laboratory/diagnostic examination: Visualization of lesion, excision and histological exam of lesion
• Treatment: Removal of warts by freezing with liquid nitrogen
• Prevention and control: HPV vaccine for individuals 11-12 years old, and safe sexual practices

HIV/AIDS

• Causative agent: Human Immunodeficiency Virus (HIV)
• Mode of transmission: Sexual contact, contact with infected blood, vertical transmission
• Incubation period: Variable, may take years
• Signs and symptoms: Opportunistic infections, malignancies, wasting syndrome
• Laboratory/diagnostic examination: ELISA, Western Blot, PCR
• Treatment: Antiretroviral therapy (ART), combination therapy
• Prevention and control: Practice safe sexual practices, use condoms, avoid sharing needles, and educate on sexual health