Inflammation of the stomach and intestines causing diarrhea, vomiting, abdominal cramps, and sometimes fever. Frequently caused by rotavirus, norovirus, or bacterial contamination of food/water.

Three or more loose or watery stools in a 24-hour period, often caused by viral, bacterial, or parasitic infections. A reportable condition under the Philippine Integrated Disease Surveillance and Response (PIDSR) system.

Joint pain without swelling or inflammation. A prominent and often debilitating symptom of dengue and chikungunya.

Showing no signs or symptoms of disease despite being infected. Asymptomatic carriers can still spread infections to others.

The proportion of a defined population that becomes ill during a specific outbreak. Calculated as (new cases ÷ population at risk) × 100.

A chronological record of changes made to data in LIGTAS, including who made the change, when, and why. Used for accountability and traceability — for example, when a CHO corrects a patient's household pin location.

The smallest administrative division in the Philippines, equivalent to a village or district. San Fernando City has 59 barangays.

Laboratory test that detects bacteria in the bloodstream. The definitive diagnostic test for typhoid fever, especially during the first week of illness.

A unique identifier automatically assigned to each reported case in LIGTAS, formatted as DISEASE-NNNN (e.g. HFMD-0042, DENGUE-0017) for tracking and reporting.

The proportion of confirmed cases of a disease that result in death within a specified period. An important measure of disease severity.

A viral disease transmitted by Aedes mosquitoes, causing sudden high fever and severe joint pain (arthralgia) that can persist for months. The name derives from a Makonde word meaning "that which bends up," referring to the stooped posture of sufferers.

An alphavirus transmitted primarily by Aedes aegypti and Aedes albopictus mosquitoes. Belongs to the Togaviridae family.

City Health Office — the local government unit responsible for public health services in San Fernando City, La Union.

City Health Office — the local government unit responsible for delivering public health services within a chartered city, including disease surveillance, immunization, and health education.

An aggregation of cases of a disease grouped closely together in space, time, or both, suggesting a common source or transmission pathway.

A patient with laboratory-confirmed HFMD infection through PCR or viral culture testing.

Redness of the conjunctiva (the membrane covering the white of the eye) without discharge or inflammation. A characteristic finding in leptospirosis.

The process of identifying and following up with people who may have been exposed to an infectious disease like HFMD.

A type of enterovirus commonly responsible for HFMD. Coxsackievirus A16 is the most frequently identified strain causing hand, foot, and mouth disease.

The most common viral cause of HFMD, generally causing milder illness compared to EV-A71. Member of the enterovirus genus.

Loss of body water exceeding intake. A major risk in AWD/AGE patients, especially young children. Managed via oral rehydration solution (ORS) or IV fluids in severe cases.

A mosquito-borne viral infection transmitted by Aedes aegypti mosquitoes, caused by any of four dengue virus serotypes (DENV-1 to DENV-4). Causes high fever, severe headache, joint and muscle pain, rash, and in severe cases hemorrhagic complications.

The four distinct serotypes of dengue virus. Infection with one provides lifelong immunity to that serotype but only short-term protection against the others. Secondary infection with a different serotype increases the risk of severe dengue.

An organism (typically an arthropod such as a mosquito or tick) that transmits a pathogen from one host to another. Aedes aegypti is the primary vector for dengue.

Department of Health — the executive department of the Philippine government responsible for ensuring access to basic public health services and managing the national health system.

The constant presence of a disease in a specific population or geographic area at a relatively stable, baseline rate.

A group of viruses that cause HFMD, including Enterovirus A71 (EV-A71) and Coxsackievirus A16, which are the most common strains.

A common cause of HFMD, especially associated with severe neurological complications including encephalitis. Outbreaks have been recorded across Asia-Pacific including the Philippines.

A widespread occurrence of an infectious disease in a community at a particular time, affecting more people than expected. Larger in scale than an outbreak.

A standardized way of counting weeks for disease surveillance, usually running Sunday-Saturday and numbered 1-52 (or 53) per year.

The study of how diseases spread in populations, including frequency, distribution, and determinants of health and disease.

A virtual geographic boundary, defined by GIS, that triggers a response when a device enters or leaves the area. LIGTAS uses geofencing to ensure household pinpoints fall within the selected barangay.

A standard format for encoding geographic data structures using JSON. LIGTAS uses GeoJSON to store and exchange barangay boundary polygons.

Geographic Information System — a framework for gathering, managing, and analyzing data rooted in the science of geography. LIGTAS uses GIS to map HFMD cases per barangay and purok.

Cleaning hands using soap and water or alcohol-based hand sanitizer to remove pathogens and prevent infection spread. A primary intervention for HFMD and AWD.

When a sufficient proportion of a population has become immune to an infection, reducing the likelihood of infection for individuals who lack immunity.

Hand, Foot, and Mouth Disease — a common viral illness caused by enteroviruses, typically affecting children under 5 years old. Symptoms include fever, mouth sores, and skin rash on hands and feet.

Blood tests that detect antibodies the body produces against pathogens. IgM indicates recent infection; IgG indicates past infection or immunity.

The process of becoming immune or resistant to an infectious disease, typically through vaccination. Includes both primary and booster doses.

A patient whose infection was acquired outside the surveillance area (e.g. while traveling) but is reported within the local jurisdiction.

The number of NEW cases of a disease occurring in a population over a specified period.

The time between exposure to the HFMD virus and the appearance of symptoms, typically 3 to 7 days.

The first identified patient in an outbreak, used as the starting point for contact tracing and epidemiological investigation.

A trained health worker (typically from the CHO) assigned to follow up on a reported case, conduct interviews, gather clinical samples, and oversee isolation compliance.

The recommended period during which a confirmed or suspected HFMD patient must avoid contact with others to prevent transmission, usually 7 to 10 days.

Tiny white spots with bluish-white centers found inside the mouth (on the buccal mucosa) — an early diagnostic sign of measles appearing 1-2 days before the rash.

An open-source JavaScript library for interactive maps used by LIGTAS to render barangay polygons, case markers, and pinpoint locations.

A genus of spiral-shaped bacteria (spirochetes) that cause leptospirosis. Survives in moist environments and is shed in the urine of infected animals, primarily rodents.

A bacterial infection caused by Leptospira bacteria, commonly transmitted through contact with water or soil contaminated by infected animal urine (especially rats). Often spikes after flooding events. Symptoms include fever, severe muscle pain, and calf pain.

Local Government Unit — a subnational administrative entity in the Philippines such as a province, city, municipality, or barangay.

A patient whose infection was contracted within the local surveillance area, indicating active local transmission.

A patient assessed with mild symptoms not fully meeting HFMD criteria, requiring monitoring but classified as low risk for community spread.

A barangay with 1-7 cases of a tracked disease in the current year. Highlighted in yellow on the LIGTAS surveillance map.

A highly contagious viral disease characterized by fever, cough, runny nose, red eyes (conjunctivitis), and a distinctive red rash that spreads from the face downward. Preventable through MCV (measles-containing vaccine).

The reference laboratory test for diagnosing leptospirosis. Detects antibodies against Leptospira in blood serum.

A barangay with 8-14 cases of a tracked disease in the current year. Highlighted in orange on the LIGTAS surveillance map.

The state of being diseased or unhealthy within a population. Morbidity rate measures the incidence of illness in a population over time.

The genus of viruses to which the measles virus belongs. A single-stranded RNA virus transmitted via respiratory droplets.

Death, especially on a large scale. Mortality rate measures the frequency of death in a defined population during a specified interval.

Muscle pain. A common symptom across many viral illnesses including dengue, leptospirosis, and chikungunya.

A patient initially suspected of having a disease but whose laboratory testing returned negative results, ruling out the suspected condition.

OpenStreetMap geocoding service used by LIGTAS to convert barangay/purok addresses into geographic coordinates for map plotting.

A disease that healthcare providers are legally required to report to public health authorities. The 7 diseases tracked by LIGTAS are all notifiable in the Philippines.

A rapid diagnostic test for dengue that detects the NS1 antigen produced by all four serotypes. Most sensitive during the first 5 days of illness.

A collaborative open-source map of the world used as the base tile layer for the LIGTAS GIS surveillance map.

A glucose-electrolyte solution given orally to replace fluids lost through diarrhea and vomiting. The WHO-recommended first-line treatment for AWD/AGE.

An occurrence of disease cases in excess of normal expectation for a given population, season, or area. Triggers active surveillance and response measures.

Coordinated public health actions taken to investigate, contain, and end a disease outbreak. Includes case investigation, contact tracing, vector control, and risk communication.

In LIGTAS, a purok or barangay is flagged as a risky zone when 3 or more HFMD cases are reported within the same area within a monitoring period.

An epidemic occurring on a global scale, crossing international boundaries and affecting a large number of people.

A unique identifier automatically assigned to each registered patient in LIGTAS, formatted as LGTS-NNNN (e.g. LGTS-0123).

Polymerase Chain Reaction — a laboratory method used to detect and identify the specific virus causing HFMD from throat swab, vesicle fluid, or stool samples.

A measure expressing the number of cases relative to the total population, usually per 100,000 people, allowing fair comparison between areas of different sizes.

Pinpoint round red or purple spots on the skin caused by minor bleeding from broken capillary blood vessels. A common sign in dengue and other hemorrhagic conditions.

Philippine Integrated Disease Surveillance and Response — the national system for monitoring notifiable diseases, established by the Department of Health.

A precise household-level latitude/longitude coordinate captured at case-report submission, allowing investigators to locate the patient's exact residence rather than just the barangay or purok.

The total number of cases (new AND existing) of a disease in a population at a specific point in time.

A patient whose symptoms strongly suggest a specific disease and who has an epidemiological link to a confirmed case, but who has not yet been laboratory-confirmed.

The period between the appearance of initial symptoms and the development of the disease's characteristic features (e.g. fever and cough before the measles rash).

Philippine Standard Geographic Code — a 9-digit code uniquely identifying every region, province, city/municipality, and barangay in the country. Used in LIGTAS for standardized geographic referencing.

A subdivision within a barangay, used for more precise geographic identification of HFMD cases in LIGTAS.

Restriction of movement of healthy people who may have been exposed to a contagious disease, to monitor for symptoms and prevent potential spread.

A sample collected from the rectum used to detect enteric pathogens. Useful in HFMD diagnosis since enteroviruses shed via the fecal route.

The average number of secondary infections produced by one infectious individual in a fully susceptible population. R0 > 1 indicates epidemic potential.

Rural Health Unit — the primary government health facility at the municipal level providing preventive, promotive, curative, and rehabilitative health services.

In LIGTAS, a barangay flagged as high-risk when it has 15 or more cases of a tracked disease in the current year. Visually highlighted in red on the surveillance map.

Small, faint pink macules typically appearing on the trunk during the second week of typhoid fever. A classic but inconsistent finding seen in about 30% of cases.

Reverse Transcription Polymerase Chain Reaction — a laboratory technique used to detect viral RNA. Considered the gold standard for confirming many viral infections including measles and dengue.

The bacterial pathogen causing typhoid fever. Strictly human-adapted — there is no animal reservoir. Transmitted via the fecal-oral route through contaminated food and water.

Laboratory test that grows microorganisms from a stool sample to identify pathogens causing diarrhea or gastroenteritis. Used for AWD/AGE workup.

A LIGTAS map mode that displays one dot per case scattered randomly within each barangay polygon, giving an at-a-glance sense of case density.

A visualization technique used in LIGTAS where multiple cases in the same barangay are displayed as dots arranged in a spiral around the barangay centroid, preventing marker overlap while preserving the count.

Systematic ongoing collection, analysis, and interpretation of health data essential to the planning, implementation, and evaluation of public health programs.

A patient who presents with symptoms consistent with HFMD (fever, mouth sores, hand/foot rash) but has not yet been laboratory confirmed.

Exhibiting observable signs and symptoms of disease.

A sample collected from the back of the throat using a sterile swab, used to detect respiratory pathogens including the HFMD-causing enteroviruses.

A simple clinical test for dengue: a blood pressure cuff is inflated for 5 minutes; a positive result is 10+ petechiae per square inch on the forearm, suggesting capillary fragility.

The examination of disease counts over time (weekly, monthly, yearly) to detect increases, decreases, or seasonal patterns that may signal an outbreak.

A bacterial infection caused by Salmonella Typhi, transmitted through contaminated food and water. Causes prolonged fever, abdominal pain, headache, and characteristic "rose spots" rash. Preventable through typhoid vaccine and water sanitation.

The administration of a vaccine to stimulate the immune system to develop protective immunity against a specific disease.

Activities aimed at reducing or eliminating disease-carrying organisms, such as fogging for mosquitoes or removing stagnant water breeding sites.

A small blister containing fluid that appears on the hands, feet, and in the mouth of HFMD patients as part of the characteristic rash.

A small fluid-filled blister on the skin or mucous membrane, characteristic of HFMD lesions on the hands, feet, and mouth.

A sample taken from the fluid inside skin blisters (vesicles) of HFMD patients for viral identification through PCR or culture.

Practices that ensure safe water supply free of contamination, critical for preventing AWD, typhoid, and other waterborne diseases.

A standardized DOH report summarizing the number of new cases of notifiable diseases observed in a given epidemiological week. Submitted by each LGU.

A disease that can be transmitted from animals to humans. Leptospirosis is a notable zoonotic disease (transmitted from rats).