EPIDEMIOLOGY OF SPECIFIC COMMUNICABLE DISEASES

EPIDEMIOLOGY OF SPECIFIC COMMUNICABLE DISEASES. Unit 5.

CONTENT. Background Diseases caused by viruses Diseases Caused By Bacteria Diseases caused by Chlamydiae Diseases caused by Fungi Diseases caused by Protozoa.

BACKGROUND. Health Professions Act 56 of 1974 is a South African law that regulates the training, registration, and practice of health professions (HPCSA) . Health Professions Act 56 of 1974 : Regulations defining the scope of the profession of environmental health practitioners National Health Act 61 of 2003 provides a framework for a structured uniform health system within South Africa. Section 32(1) of the National Health Act 61 of 2003 defines municipal health services as a function of the District and Metropolitan Municipalities. National Health Act: Regulations relating to the Surveillance and the control of notifiable medical conditions.

NOTIFIABLE DISEASES. Category Must be reported immediately using the most rapid means upon clinical or laboratory diagnosis followed by a written or electronic notification within 24 hours of diagnosis. 1 NMC (22) Acute flaccid paralysis Acute rheumatic fever Anthrax Botulism Cholera Diphtheria Enteric fever (typhoid or paratyphoid fever) Food borne disease outbreak Haemolytic uraemic syndrome (HUS) Listeriosis Malaria Measles Meningococcal disease Pertussis Plague Poliomyelitis Rabies (human) Respiratory disease caused by a novel respiratory pathogen Rift valley fever (human) Smallpox Viral haemorrhagic fever diseases Yellow fever.

NOTIFIABLE DISEASES. Category 2 NMC (21) Must be reported through a written or electronic notification, within 7 days of clinical or laboratory diagnosis but preferably as soon as possible following diagnosis. Agricultural or stock remedy poisoning Bilharzia (schistosomiasis) Brucellosis Congenital rubella syndrome Congenital syphilis Haemophilus influenzae type B Hepatitis A Hepatitis B Hepatitis C Hepatitis E Lead poisoning Legionellosis Leprosy Maternal death (pregnancy, childbirth, puerperium) Mercury poisoning Soil transmitted helminths (Ascaris Lumbricoides, Trichuris trichiuria, Ancylostoma duodenale, Necator americanus) Tetanus Tuberculosis: pulmonary Tuberculosis: extra-pulmonary Tuberculosis: multidrug-resistant (MDR-TB) Tuberculosis: extensively drug-resistant (XDR-TB).

NOTIFIABLE DISEASES. Must be reported weekly by all public and private laboratories. Category 3 NMC Ceftriaxone-resistant Neisseria gonorrhea West Nile virus, Sindbis virus, Chikungunya virus Dengue fever virus, other imported arboviruses of medical importance Salmonella spp. other than S. Typhi and S.Paratyphi Rubella virus Shiga toxin-producing Escherichia coli Shigella spp..

NOTIFIABLE DISEASES. Category 4 NMC Must be reported monthly by Healthcare-associated infections or multidrug- private and public health resistant organisms of public health importance laboratories. • • • Carbapenemase-producing Enterobacteriaceae Vancomycin-resistant enterococci Staphylococcus aureus: hGlSA and GISA Colistin-resistant Pseudomonas aeruginosa Colistin-resistant Acinetobacter baumanii Clostridium difficile.

DISEASES CAUSED BY VIRUSES.

DISEASES CAUSED BY VIRUSES. Haemorrhagic Fevers of Africa, Measles, Mumps, Poliomyelitis, Rabies, Rubella, Viral Hepatitis..

VIRAL HAEMORRHAGIC FEVERS OF AFRICA. Group of illness caused by 4 families of viruses, Common features: affect many organs, damage the blood vessels, affect the body’s ability to regulate itself. Mild to severe condition(death).

VIRAL HAEMORRHAGIC FEVERS OF AFRICA. Ebola fever Yellow fever Lassa Fever Epidemiology Rural areas-West & Central Africa Central Africa Rural areas of west Africa Sources of contamination Monkey Aedes aegypti Mosquito Rat Mode of transmission Person-to-person via contact with bodily secretions (including sexual intercourse) Mosquito bite Person-to-person via contact with bodily secretions (including sexual intercourse) Clinical signs and symptoms Sudden onset, malaise, fever, myalgia, Hypotension & shock Sudden onset, malaise, fever. Gradual onset, malaise, fever, sore throat. Hypotension & shock Incubation period 2-21 days 3-6 days 6-21days.

VIRAL HAEMORRHAGIC FEVERS OF AFRICA. Ebola fever Yellow fever Lassa Fever Infectious period 2-3 months Central Africa 2-3 months Case-fatality rate 50-90% hospitalized cases 10% hospitalized cases 15-20% hospitalized cases Prevention and control Strict isolation of clinical case, strictly handling of body fluids. Immunization, Vaccination Avoid contact with rat excreta, strictly isolation of clinical case, Strictly handling of body fluids.

Ebolavirus Ecology Enzootic Cycle New evidence strongly implicates bats as the reservoir hosts for ebolaviruses. though tt•æ means of local enzootic maintanance and transnssion of the virus within bat populations remain unknown. Ebolaviruses: Ebola virus (formerly Zaire virus) Sudan virus Forest virus Bundibugyo virus Reston virus (non-human) Epizootic Cyde Epizootics caused by ebolaviruses appear sporadically. producing high mortabty among non-human and duikers and may precede human outbreaks. Epidemics caused by ebolaviruses produce acute disease among humans, with the exception of Reston virus which does produce detectable disease in humans. Little is known about how the virus frst passes to humans. triggering waves of human-to-human transmission, and an epidemic Human-to-human transmission is a predominant feature of epidemics. Following initial human infectibn through contact with an infected bat or other Wiki anirml. human-to-human often occurs..

EBOLA: KILLER VIRUS An outbreak of the deadly Ebola virus is spread by close contact and kills between 25 and 90 percent of victims. There is no cure or vaccine SYMPTOMS O Early stages Advanced stages Sore throat Impaired liver and kidney Diarrhoea O Vomiting O Rash Headache O Fever OFatique Bleeding from eyes, nose and mouth Muscle pain Preventative measures •Stop contact With infected animals and the consumption of their meat • Isolate the sick •Prompt disposal of victims' bodies • Disinfect homes Of dead and infected • protective clothing for healthcare workers Internal and external bleeding Source: *0+0.

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Measles or Rubeola, is an acute viral illness caused by a virus in the family paramyxovirus, genus Morbillivirus..

Measles is characterized by a prodrome of fever and malaise, cough, coryza, and conjunctivitis, followed by a maculopapular rash..

MEASLES. Measles is usually a mild or moderately severe illness. However, measles can result in complications such as pneumonia, encephalitis and death. Measles transmission is airborne by respiratory droplet nuclei spread or it can be transmitted by direct contact with infected nasal or throat secretions. The incubation period is approximately ten days but varies from 7 to 18 days from exposure to the onset of fever. It is usually 14 days until the rash appears..

Anyone who never had measles and has never been vaccinated. Babies younger than 12 months old, because they are too young to be vaccinated. Adults who were vaccinated before 1968, because some early vaccines did not give lasting protection. A very small percentage of vaccinated children and adults who may not have responded well to the vaccine..

PREVENTION OF MEASLES. Avoid exposing children to any person with fever or with acute catarrhal symptoms Isolation of cases from diagnosis until about 5-7 days after onset of rash Disinfection of all articles soiled with secretion of nose and throat Encourage by health department and by private physician of administration of measles immune globulin to susceptible infants and children under 3 years of age in families or institutions where measles occurs. Live attenuated and inactivated measles virus vaccines have been tested and are available for use in children with no history of measles, at 9 months of age or soon thereafter.

Continent N. America Island state Europe Jan '08 - Apr '11 Africa Country USA New Zealand France Bulgaria Zimbabwe South Africa Dates Jan —Aug '13 May '11 Cases >150 >400 Apr Sep '10 '10 - Jul '12 '09 -Jul '08 '09 — May Sep '09 — May Deaths 8 24 517 18.

MEASLES VERSUS GERMAN MEASLES Measles is caused by a virus which specifically infects the respiratory system More severe and can be life threatening Results in a red or reddish-brown rash German measles is caused by a virus, which invades the lymph nodes, skin and eyes Benign or milder disease, but pregnant woman should be cautious Include red spots with a white center known as Koplik spots, in oral cavity Pedica.ec•nu.

DISEASES CAUSED BY BACTERIA.

DISEASES CAUSED BY BACTERIA. Anthrax, Brucellosis, Cholera, Diphtheria, Leprosy, Leptospirosis, Meningitis, Pertussis, Pneumonia, Relapsing Fever, Salmonellosis, Shigellosis, Staphylococcal infections, Streptococcal infections, Tetanus, Typhoid fever..

Bacteria. MOT/ SOC Clinical symptoms Prevention/ control Anthrax Inhalation, ingestion, through skin abrasions Fever, respiratory distress depending on the type Antibiotics, vaccines, correct burial of carcasses cholera faecal-oral route/water Fever, vomiting, diarrhoea (rice-like stool), muscle cramps, Environmental interventions, proper sanitation, health education Leprosy Person-to-person/ respiratory tract Anaesthesia, swelling and contraction of fingers (depending on the type) Improve sanitation, vaccines available Staphylococcus infections Direct contact, Impetigo, boils, diarrhoea in food poisoning cases Aseptic techniques, screening, restrictions of infected persons Meningitis Airborne route High fever, haemorrhagic lesions, headache, stiff neck (depends on strain) vaccine, quarantine, prophylaxis Typhoid Oral /faecal-oral route/water, food Lethargy, malaise, fever, aches and pains, nausea, vomiting, diarrhoea, abdominal tenderness vaccine.

3 Strains Cutaneous(skin) Inhalation(lungs) Gastrointestinal (digestive) Caused by bacteria Bacillus anthracis.

Humans can become infected after handling infected animals Breathing anthrax spores from infected products Eating undercooked meat from infected animals.

Can be used as a biological weapon USA 2001-anthrax spores spread through postal system via letters containing spores.

1-7 days Inhalation anthrax- 7-60 days Raised itchy bump (resembles incest bite) 1-2 days, develops into a vesicle (cyst) Develops into painless ulcer (1-3cm diameter) Ulcer has black center Swelling of surrounding tissues Swelling of adjacent lymph glands.

The Anthrax Cycle Biting Fly From infected anima/ Ingestion Forms Bacteria Exposure in animal oxygen waste and decomposition.

Skin lesion from anthrax Skin anthrax lesion on the neck.

Anthrax Distribution Hyperememc epoemx Sporük 20,000 to 100,000 cases estimated globally/year http ://www.vetmed.lsu.edu/whocc/mp_world.htm Pudic 2011.

Anthrax vaccine, Antibiotics-after exposure Avoid contact with infected animals, Don’t eat improperly slaughtered/cooked meat-if not declared safe for human consumption, Proper disposal of infected carcasses (burial or other metheds),.

CHOLERA. Cholera is an acute diarrheal illness caused by infection of the intestine with the bacteria Vibrio cholerae It is a global public health threat and indicates inequity and lack of social and economic development. It is spread by ingestion of contaminated food or water Access to safe water, basic sanitation and hygiene is essential to prevent cholera and other waterborne diseases..

CHOLERA- SYMPTOMS. Cholera can cause severe acute watery diarrhoea, which can be fatal within hours if untreated Most people are asymptomatic but can spread the bacteria through their faeces for 1–10 days. Symptoms appear 12 hours to 5 days after infection Symptoms Nausea Vomiting Diarrhoea Dehydration Fever Dry Mouth Low blood pressure Rapid heartbeat.

CHOLERA- PREVENTION. Strengthening surveillance, Strengthen surveillance: Implement robust surveillance systems to detect cholera cases early and track outbreaks. Improve environmental monitoring: Monitor water sources, sanitation facilities, and food handling practices to identify potential risks. Improving access to portable water, Provide access to potable water sources: This could include wells, boreholes, or piped water supplies that are treated to remove cholera bacteria. Chlorinate water: Chlorine treatment can effectively kill cholera bacteria. Educate the public on safe water storage and use: This includes advising on proper storage containers, filtering methods, and boiling water practices Sanitation and hygiene ( WASH), Promote frequent handwashing: Encourage frequent handwashing with soap and clean water, especially before and after preparing food, before eating, and after using the toilet. Provide handwashing stations: Set up handwashing stations near latrines and in public places..

CHOLERA- PREVENTION. Health Education and community engagement, Conduct health education campaigns: Educate communities about the risks of cholera, the importance of hygiene and sanitation, and how to prevent the spread of the disease. Involve community members in cholera prevention efforts: Empower communities to take ownership of their health and safety by involving them in the planning and implementation of cholera control measures..

Diseases caused by Chlamydiae.

Chlamydiae/ Rickettsia. MOT/ SOC Clinical symptoms Prevention/ control Chlamydia- Trachoma Direct (sexual) or indirect contact Impaired vision Proper sanitation/ hygiene, Rickettsia- Q-fever Vectors or indirect contact, airborne Fever, chills, malaise pasteurized milk, avoid ticks, health education.

Sexually transmitted infections-Groups. HIV AIDS; Gonorrhoea; Herpes; Syphilis; Trichomoniasis.

43. Risk Factors. Adolescence New or multiple sex partners History of STI Presence of another STI Oral contraceptive user Lack of barrier contraception.

Diseases caused by Fungi.

45. Fungi. Fungal disease are usually divided into four types: Superficial, Cutaneous, Subcutaneous and Systemic. Superficial Fungal Infections: Dermatophytosis (ringworm): Skin, nail, and hair infections caused by various fungal species. Subcutaneous and Cutaneous Fungal Infections: Sporotrichosis: A skin infection caused by Sporothrix fungi, often acquired through contaminated soil or plant matter. Systemic Fungal Infections: Aspergillosis: An infection caused by Aspergillus molds, often affecting the lungs..

Fungi. MOT/ SOC Clinical symptoms Prevention/ control Tinea capitis /ring worm of the scalp Direct contact, fomites Scaly swellings, red rings, itching, dandruff, bald patches, broken hair Good hygiene, avoid overcrowding Tinea corporis/ ring worm of the body Direct contact, fomites Scaly swellings, red rings, itching, Keep skin dry, good hygiene Tinea cruris ( Jock’s itch). fungal infection that causes an itchy, ring-shaped rash in the groin and inner thigh area. dermatophyte fungi Direct contact, fomites Itching , groin, rash, redness Keep skin dry, good hygiene Tinea pedis ( Athlete’s foot) common fungal infection that affects the foot. associated with sports and athletes Direct contact, fomites Scaly rash, itching, burning, stinging, dryness, fissures good hygiene Tinea inguium, a fungal infection that affects the nails (both fingernails and toenails). Direct contact, fomites Brittle nails, crumbly nails good hygiene.

Diseases caused by Protozoa.

Protozoa. MOT/ SOC Clinical symptoms Prevention/ control Leshmaniasis Vector borne (sandflies) Lesions on the skin Vector control, environmental interventions Giardiasis Faecal-oral route Diarrhoea, dark greasy faeces, flatulence, abdominal discomfort, nausea Proper treatment of water sources Plasmodium Malaria Vector borne Fever, sweating, chills, shivering, nausea, vomiting , diarrhoea Vector control, chemoprophylaxis, insect repellents Toxoplasmosis Direct contact/ingestion High fever, weakness, respiratory illness Avoid handling domestic cats, avoid raw meat Amebiasis Oral /faecal-oral route/water, food Lethargy, malaise, fever, aches and pains, nausea, vomiting, severe diarrhoea, bloody stools, abdominal pains Proper treatment of water sources, good sanitary practices in human faecal waste treatment.

Malaria. Malaria is caused by a protozoan parasite belonging to the genus Plasmodium. There are four species of Plasmodium that primarily infect humans: P. falciparum, P. vivax, P. ovale, P. malariae. Humans are infected with Plasmodium protozoa when bitten by an infective female Anopheles mosquito vector. Globally in 2023, there were an estimated 263 million malaria cases and 597 000 malaria deaths in 83 countries. The WHO African Region carries a disproportionately high share of the global malaria burden. In 2023, the WHO African Region was home to 94% of malaria cases (246 million) and 95% (569 000) of malaria deaths. Children under 5 accounted for about 76% of all malaria deaths in the Region. Malaria is endemic in some areas of South Africa, namely north-eastern KwaZulu-Natal, parts of Mpumalanga and Limpopo. September to May is considered the malaria season..

Malaria. Incubation period Incubation period of malaria may be as short as 7 days after exposure but on average 10 to 21 days in patients who are non-immune and have not taken chemoprophylaxis. (Incubation periods may be prolonged in patients who have taken prophylaxis ) Symptoms Severe symptoms include: extreme tiredness and fatigue impaired consciousness multiple convulsions difficulty breathing dark or bloody urine jaundice (yellowing of the eyes and skin) abnormal bleeding..