Extreme weather –floods

Heat

Decreased water availability

Exposure to pollutants

Injuries

Cardiovascular Disease

Food Insecurity

Water-borne diseases

Respiratory Diseases

Climate Change

Deforestation

Urbanization

Changes in disease transmission dynamics

– Vectors, loss of biodiversity

Decreases in food yields

Loss of natural medicines (declines in biodiversity)

Mental Health – cultural impoverishment, nature deficit syndrome

Climate Change

Deforestation

Land Degradation

Changes in Hydrology

Urbanization

Emerging Infectious Diseases

(Ebola, West Nile)

New ranges for old diseases

(Malaria)

Livelihood loss

Population Displacement (Slum dwelling, Violence)

Food Insecurities /Malnutrition

Communicable Diseases

Water-borne diseases

Psychological Illness

Climate Change

Deforestation

Urbanization

High Human Densities

Poor Water Quality

Originally, competition kept tick hosts low

mouse, deer, and tick population increased with deforestation

Vector-borne diseases

Water-borne diseases

Diarrheal diseases

Soil-borne pathogens and toxins

Lack of sanitation infrastructure

Changes in agricultural productivity / food security

Addressing malnutrition

Malaria

Dengue

West Nile

Yellow Fever

Rift Valley Fever

Lymphatic Filariasis

Parasite (Plasmodium spp.)

Transmitted by Anopheles spp.

500 Million Clinical Cases / year

~1 million deaths / year

Children and pregnant women

>40% of global population at risk

A child dies every 30 seconds

Occurs in 100 Countries

90% cases in tropical Africa

malaria parasite lifecycle

Part one

Mosquito injects saliva and sporozoites (infective stage) into blood stream

– Sporozoites disappear from circulating blood in 1hr

• Sporozoites enter liver in 2 days

– initiates asexual reproduction

• Within liver next stage matures …-> infects blood cells

– Asexual reproduction in blood cells

– infective stage to mosquito is in blood

– Rupture of blood cells

10-15 days following bite

• Periodic chills and fever

– Frontal headache and muscle pain

• Young children - non-specific symptoms

– Fever, cough, vomiting, diarrhea

• Additional Symptoms

– Lack of energy, nausea, loss of appetite, abdominal pain

• Sickle Cell Trait – some protection

Severe fevers, recur every few hours to days

• Most pathogenic and accounts for most death

• Tropical and Subtropical

– Sub-Saharan Africa especially

• Disease:

– parasites sequestered to capillaries 

– Cerebral Malaria, Burkitt Lymphoma

• Classic Relapsing Malaria

– For up to 5 years post-infection

• Virus - Vectored by mosquito (Aedes aegypti)

• ~200,000 cases / year

– 30,000 deaths / year

• Vaccinations are available and required by many 

countries

Occurs only in Africa and South America

– Forestry and agricultural workers at greatest risk

– Occasional outbreaks in urban areas with migration –

becoming more common

Incubation for 6 days post bite

• Difficult to recognize early

– Confused with malaria, typhoid, hemorrhagic fevers

– Affects multiple organ systems

– Vomiting, bleeding from mouth, nose, eyes, in stool and 

vomitus

– 50% patients in toxic stage die in 10-14 days

– 50% recover without significant organ damage

Vectored by mosquitoes – Aedes aegypti

• Viral

• High fever, severe headache, backache, joint pain, 

eye pain, vomiting, and rash

• Younger children with greater immunity – milder 

illness

• Typically self-resolving

• Vector Control is current public health approach.

Trypanosoma cruzi

•South and Central America

•1990s:

•12-19 million infected 2-3 million 

with clinical symptoms 

•45,000 die/y

•Current:

•13 million in 15 countries

•200,000 cases/y

• Transmission – reduviid bugs – feces

• Intracellular parasite

– Asexual reproduction of parasite causes host cell 

death

• Trypomastigotes (infective stage) in blood

– Ingested by bug

Acute Stage

– Chagoma – swelling 

at bite

– Romañas signs

– Anemia, weakness, 

nervous disorders, 

chills, muscle and 

bone pain, heart 

failure

– Heart disease – failure

– Megacolon

– Megaesophagus

Leishmania spp.

• Vector – Sand fly (Phlebotomus)

• Leishmaniasis – complex of diseases

– Spread from Africa to SA with Slavery

– 15 million people infected (400,000/year)

– Parasite attacks the immune system

– Complicates HIV

– Complicated by some drug therapies

Wucheria bancrofti

Onchocerca volvulus

Loa loa

Dirofilaria immitis

One of the causes of Lymphatic Filariasis (Elephantiasis)

Distributed across wide equatorial belt

Central Africa, Asia, Australia, and South America

Parasite of lymphatic ducts

Periodicity of infective stage in blood corresponds to activity of the insect vector

Vectored by mosquitoes 

At least 10 Genera Including Anopheles, Aedes, and Culex

Seasonal Epidemic

Many infections with no symptoms (80%)

Mild Symptoms (~20%)

1 in 150 individuals develop serious illness

High fever, headache… severe neurological illness

Coma…death

Cholera

Shigellosis

Enterohemorrhagic E. coli

Viral Hepatitis A  (VHA)

Typhoid

Bacterial infection of Salmonella typhi

Some individuals recover, but become carriers

Can Cause Gut Perforations

waterbourne/ fecal disease

Very small intracellular parasites

Complications with AIDS patients

Prolific watery diarrhea (6-25X / day, 1-17 liters / day)

Milwaukee 1993

fecal/ water contamination

Obstruction of nutrients (especially fats)

1-2 wk incubation

Gray, Greasy, voluminous, malodorous diarrhea

fecal contamination of water

Cysts contaminate water

Invades colon –> Ulcerations 

tissue invasion and digestion

Can invade other tissues if the organism enters the bloodstream

Hepatic, brain and lung abscesses

caused by one of four pathogens

S. mansoni

S. haematobium

S. mekongi

S. japonicum

-Classic manifestation after many years with 

infection

• Chronic egg deposition
injury to tissues

– Schistosoma mansoni

• Damage to liver and intestine

– Schistosoma haematobium (Bilharzia)

• Damage to bladder

Bladder Carcinoma

– S. haematobium

– Possibly eggs function as carcinogen

• CNS Schistosomiasis

– S. mansoni & S. haematobium – spinal cord

– S. japonicum - brain

Infection via larval contact 

with skin

– Feet, hands, buttocks

• Larvae migrate to lungs, 

coughed up and 

swallowed

• Feed in intestines

– blood

Generally caused by 2 species

– Necator americanus

– Ancylostoma duodenale

Infections obtained via 

soil are dangerous

– Embryonated eggs 

ingested

– Cysticercosis

• Brain, eye, muscle

product of photosynthesis

• Blood sugar (dextrose)

• Most from breakdown of starches and sucrose

Carbohydrates 4 C/g

Proteins 4 C/g

Fats 9 C/g

fruit sugar

• Absorbed by small intestine, metabolized in liver

• Converted to glucose or used to form fat (storage)

• High fructose corn syrup – highly processed foods

typically bonded to lactose (milk)

• Metabolized to glucose or glycogen

Decreased growth

• Lack of energy

– apathy

– Effects learning

• Decreased Immunity

– Micro-organisms with 

advantage

• Entry and replication

– Poor absorption of 

nutrients (increased need)

– Breakdown of muscle / fat

– Longer recovery time

– Increase probability of 

death

– Marasmus

– Kwashiorkor

– Marasmic Kwashiorkor

• Extremely low weight

– <60 percent of 

reference weight

• Extreme wasting

– Loss of muscle and fat

• “Old Person’s Face”

– Anxious expression

• Pot Belly

– Weak abdominal 

muscles

• Irritable / fretful

•

*Edema

– Legs, arms, face

• Moon Face

– Due to edema

• Moderately low weight

– Not necessarily thin

• Wasted/weak muscles

– Pot belly

• Apathy / Misery

• Poor appetite

• Pale, thin, peeling skin

• Pale, sparse, hair

• Enlarged Liver

 Vitamins A, D, E, K

Stored in the liver and fatty tissues

vision, healthy epithelial cells, Growth, 

prevention of cardiovascular disease, Cancer 

prevention (prostate especially), Acne (vitamin A 

analogs)

also considered a hormone, regulates 

calcium and bone metabolism

antioxidant, protection against cardiovascular 

disease

Thiamin Pantothenic acid

Riboflavin Biotin

Niacin Vitamin B-6

Folate Vitamin B-12

Xerophthalmia

Infections

Most common among young children (Quick growth / deplete stores in liver)

“At Risk Places” -Dry regions – seasonally without fruits / vegetables

• Night blindness

– Difficulty seeing in dim 

light

• Corneal Lesions

– Cloudiness or sores

Beriberi

Symptoms

– Appetite loss

– Weakness (legs)

– Edema / cardiac

• At Risk

– Diets high in refined rice or 

cassava

– Breast-fed babies –

Thiamine deficient mothers

• Prevention

– Whole grains in diet

Scurvy

Sympotms:

– Anemia / lack of energy

– Swollen, bleeding gums

– Painful joints

Risk:

– Low birth-weight babies

– Children of mothers with deficiency

– Children who play indoors

– Women who cover themselves

• Prevention

– Spend at least 10 minutes / day outside

Rickets

Occurs in young 

children

• Signs

– Slow closure of soft 

spot

– Knock-knees

– Weak muscles

– Difficulty walking

Thyroid Gland

– Stores iodine

– When iodine is lacking, 

thyroid increases in size to 

collect iodine from blood

• Hypothyroidism

– Lack of energy, thinks 

slowly

• Cretinism

– Deafness, mental handicap