Communicable Diseases: Spread & Prevention

• Communicable diseases spread from person to person through blood, bodily fluids, airborne viruses, or insect bites

Spread Mechanisms for Communicable Diseases

• Direct physical contact with an infected individual, such as through touch (staphylococcus) or sexual intercourse (gonorrhea, HIV)
• Fecal/oral transmission, as seen in hepatitis A
• Transmission via droplets, exemplified by influenza and tuberculosis (TB)
• Contact with contaminated surfaces or objects, which may include the Norwalk virus
• Ingestion of contaminated food (salmonella, E. coli) or water (cholera)
• Insect or animal bites that transmit diseases, such as mosquitoes (malaria, yellow fever) and fleas (plague)
• Airborne transmission, including diseases like tuberculosis or measles

Food or Water-Borne Diseases

• Diarrheal diseases can be caused by bacteria like Salmonellae and Escherichia coli; with Shigella dysenteriae type 1 and Vibrio cholerae causing the most severe outbreaks
• Protozoa such as Giardia lamblia also cause diarrheal diseases
• Viruses like Rotavirus and the Norwalk virus can cause diarrheal disease
• Diarrheal Diseases has a case definition of three or more abnormally loose or fluid stools over 24 hours
• Primarily transmitted through the fecal-oral route, especially via food and water
• Salmonella has an incubation period of 8-48 hours and E. coli has a longer incubation period, typically 2-8 days and the symptoms usually last between 2-5 days
• Rotavirus has an incubation period of 48 hours and symptoms may last for up to one week
• Communicability lasts during the acute stage of the disease and for the duration of fecal excretion, with temporary Salmonella carriers continuing to exist for several months
• Management of diarrhea involves preventing dehydration, administering Oral Rehydration Salt or IV fluids during severe dehydration
• Antibiotic use depends on the infectious agent, and feeding should resume with a normal die when vomiting stops
• It is important to separate those eat, cook food on site, and continue breastfeeding infants and young children
• For epidemic control, it is important to inform health authorities if there is an unexpected increase in cases, confirm diagnosis and ensure prompt treatment, and confirm the outbreak follows WHO guidelines
• Safe drinking water, adequate supply, collection and storage, clean water maintenance, household storage, and safe disposal of human excreta can help in prevention
• Provision of adequate food storage facilities, cooking utensils, water, fuel, soap and handwashing guidance aids in prevention

Bacillary Dysentery (Shigellosis)

• Caused by the bacterium Genus Shigella, with Shigella dysenteriae type 1 causing the most severe cases and the largest epidemics
• Diarrhea with visible blood is the clinical case definition, and to confirm this, isolation of S. dysenteriae type 1 is required from stool
• Spread through the fecal-oral route by contaminated food and water
• Incubation period is usually 1-3 days but can extend up to one week for S. dysenteriae type 1
• Communicability lasts during acute infection and up to 4 weeks after illness if untreated, with appropriate treatment shortening it to just 2-3 days, even as asymptomatic carriers exist
• Appropriate antibiotic therapy is important; Nalidixic acid is often the first choice, with ciprofloxacin as a second option
• Dehydration prevention and case management utilizing ORS plays an important role
• Health authorities should be informed if one or more suspected cases appear
• During epidemic control, confirm the outbreak following WHO guidelines, using 10-20 stool samples taken with a rectal swab transported in Cary Blair medium to confirm cause, identify antibiotic sensitivity, and verify the outbreak

Cholera

• Bacterium Vibrio cholerae is the cause of Cholera
• The clinical definition requires a person aged over 5 years with severe dehydration from acute watery diarrhea, or a person aged over 2 with diarrhea in an area with a cholera outbreak
• Confirmed cases require isolation of Vibrio cholerae 01 or 0139 from diarrheal stool samples
• Fecal-oral route is the primary transmission route via water and food
• Incubation period is usually between 1 and 5 days
• Communicability occurs during the symptomatic phase and lasts until 2-3 days after recovery, but rarely can extend for months
• Managing cholera include dehydration treatment using ORS or IV fluids such as ringer lactate during severe cases
• Antibiotics, like doxycycline/tetracycline, is not essential but may shorten diarrhea duration
• For epidemic control, inform the Health Authorities if there are one or more suspected cases including stool sample test that meets Who Guidlines
• Two oral cholera vaccines are available: a killed cholera vaccine and a live attenuated vaccine.

Typhoid Fever

• Salmonella typhi is the bacterial agent
• Clinical diagnosis is difficult therefore any suspected case by a clinician is considered relevant
• Confirmed cases can be confirmed by laboratory analysis or blood/stool
• Spreads via the fecal-oral route and food and water
• Incubation takes 8-14 days, or 3 days up to a month
• Communicability can last from the symptomatic period for 2 weeks.
• Antimicrobial treatment should selected according to strain: ciprofloxacin; cotrimoxazole; chloramphenicol; ampicillin is usually prescribed
• A mass immunization with parental vaccines can control typhoid if medical resources arnt available
• Avoid vaccinating children under 2 years old or person using antibiotics

Poliomyelitis

• An Enterovirus and its main types are 1, 2, 3
• Acute flaccid paralysis (AFP) in a child aged <15 years or any paralytic illness
• Infection is confirmed through lab analysis of stool sample
• Virus is highly communicable through fecal-oral route
• There exists a 10—21 day incubation period between infection and onset of paralysis
• Communcability from first infection is around 36 hours and for the next 4-6 weeks
• Preventative measure are implemented through supplementary immunization activity

Acute Lower Respiratory Infections (ALRI)

• Streptococcus pneumoniae & Haemophilus influenzae are the common bacteria involved
• Includes Pneumonia, Bronchitis, Bronchiolitis
• Pneumonia is fatal to 10-20% of infected if not appropriately treated
• Symptoms involve cough or difficult breathing
• Breathing rates are important to identifying Alri ( 50 or more times per minute for infants aged 2 months to 1 year or Breathing 40 or more times per minute for children aged 1 to 5 years
• General danger signs include an inability to drink or breast feed, vomiting, convulsions, or being lethargic or unconscious
• Transmitted in the air and incubation is usually 2-5 days
• Communicability depends on infective agent with symptomatic phase
• For prevention, assess signs of malnutrition, and use antibiotics depending on what is available locally
• Feeding, fluids, and warmth are all important is helping the body deal with the condition.

Measles

• A respiratory disease that is caused by the Measles virus Clinical case definition involves symptoms such as fever, maculopapular rash (not vesicular), cough, runny nose or red eyes
• Isolation is confirmed by isolation of the IgM antibodies ( At least a fourfold increase in antibody titre or presence of measles specific IgM antibodies)
• Measles is primarily transmitted through the air via contact with infected nasal discharges, with an incubation period of 10-12 days
• Patients are most infectious 4 days before the rash until 1-2 days after rash onset
• Immunization is the best preventative measures
• Vitamen A supplement must be taken prophylactIcally.
• The priority is to immunize all children up to 5 years regardless of vaccination status and medical history
• Implement injection safety guidelines as set forth by the safe sharp's programs
• Manage fever with treatment, if there are complications, refer the case to a medical facility.

Tuberculosis

• Mycobacterium tuberculosis, M. tuberculosis, M. africanum(Humans), M. Bovis (cattle)
• Can be identified positively and negatively(Pulmonary TB smear-positive & Pulmonary TB smear-negative)
• Requires multiple tests to confirm, AFB count must be accurate.
• Can be suspected if cough lasts a long time, combined with blood, chest pains and breathlessness
• Usually spread through small water droplets
• Incubation to symptoms may only be weeks but some patients can have latent infections their whole life
• The viable tubercullus bacilli are communicable through the sputum. Effective treatment makes a patients noconomic
• A priority is to diagnose and treat the disease with a DOTS strategy to ensure appropriate treatment (Directly Observed Treatment Short Course) Combing sputum & chemotherapy are main types of treatment
• A combotheriphutic regimen must be put into effect to treat tuberculosis
• Chem is separated into 5 main sections.

Meningococcal Disease (Meningitis)

• Caused by Bacterium: Neisseria meningitidis serogroups A,B,C,Y,W1
• Can be identified through sudden onset of fever combined with: neck stiffness, altered consciousness, other meningeal sign, or petechial or purpural rash
• Cases can be identified in patients with fever and bulging area Can spread through blood
• Positive cerebrospinal fluid antigen detection or cerebrospinal fluid positive culture or blood positive culture is how Meningitis can be assessed
• The disease spreads through the air, and takes about 2-10 days for incubation
• The disease is communicable form start of symptoms until 24 hours after antibiotic intake
• Treatment involved prompt response with antibiotics.
• Supportive medication is important to treat the condition.

Vector-Borne Diseases: Malaria

• Protozoan parasites such as Plasmodium vivax, Plasmodium falciparum, Plasmodium malariae, and Plasmodium ovale is the cause for malaria.
• Clinical case definition is history of fever within the last 48 hours.
• The diseases is identified through blood samples and observation of parasites in the blood Main method for transmission is mosquitos
• Anopheles superpictus is the main vector for carrying the disease Can sometime transmit to babies due to trans-placental transfer or contact with blood.
• Incubation is roughly 12-17 days but can appear between 1 week after and 2 months following exposure.
• If untreated, the disease can last for years
• Treatment is dependent with the species contracted and require drug treatment.
• Prevention is accomplished through the elimination of residual insecticide spraying of shelters, insecticide-treated bednets.
• An effort to create high efficient public health education systems is important when educating people of the risk of contracting the malaria.

Dengue Fever

• A vector-borne disease transmitted by mosquitoes and caused by the Flavivirus group
• Presence of immunoglobin is the primary idicicant for identifying the infection
• Spread primary biting by mosquitos.
• Symptoms: high fever, headache, retro-orbital pain, muscle and joint pain, rash, haemorrhagic manifestations, and leucopenia
• Takes 3 - 14 days until symptoms are apparent
• Is not readily communicable after the host is infection ( no person top person transmission)
• Supportive treatment include monitoring patient and taking blood.
• Although symptoms may appear manageable, if un treated, then a person can develop dengue haemorrhagic which is deadly
• Epidemics can happen when larvae and mosquitos spread or the patient not using bug spray or protective clothing

Vector Diseases: Plague

• Caused by bacterium: Yersinia pestis
• Identifiable through observation of physical marks, and blood test
• Can be assessed through examining buboes, blood, or sputum which would then be tested for Yersinia pestis.
• Spread by rats is also known to increase infections in people
• Can transmit with a small amount of body fluid
• Incubation from contact can be from 1-7 days
• There is need for treatment (mostly antibiotic) in short time, before the infection kills the host.
• If plague can easily transmit through the air there will be pneumic plauge
• Patients should be isolated and be cared for with protective equipment.

Zoonotic diseases : Rabies

• Caused by virus called: Rhabdovirus, genus Lyssavirus
• Symptoms include hyperactivity, insomnia, anxiety, confusion, paralysis etc
• Post-mortum an brain sample must be taken, by FA or with pcr.
• If patient bit before death, extract for analysis is appropriate by FA.
• Supportive Care can be cleaning the wound immediately with detergent
• Modern rabies vaccine (Vero cell or chick embryo cell) is important against a positive case
• In many infections death is inevitable, must follow proper protocol.
• Killing suspected animals within area will help stop spread

Zoonotic disease : Anthrax

• Caused by Bacterium: Bacillus anthracis
• Infection includes: Cutaneous, Gastro-intestinal, Pulmonary (inhalation), Meningeal
• Anthrax is not contagious however deadly
• Extraction of fluids will help in the analysis
• If anthrax appears in animal check animals for sign of infection, remove the animal immediately and ensure sterilization of the region.