When properly treated, people with malaria can usually expect a complete recovery. However, severe malaria can progress extremely rapidly and cause death within hours or days. In the most severe cases of the disease, fatality rates can reach 20%, even with intensive care and treatment. Over the longer term, developmental impairments have been documented in children who have suffered episodes of severe malaria. Chronic infection without severe disease can occur in an immune-deficiency syndrome associated with a decreased responsiveness to "Salmonella" bacteria and the Epstein–Barr virus.

During childhood, malaria causes anemia during a period of rapid brain development, and also direct brain damage resulting from cerebral malaria. Some survivors of cerebral malaria have an increased risk of neurological and cognitive deficits, behavioural disorders, and epilepsy. Malaria prophylaxis was shown to improve cognitive function and school performance in clinical trials when compared to placebo groups.

Malaria parasites belong to the genus "Plasmodium" (phylum Apicomplexa). In humans, malaria is caused by "P. falciparum", "P. malariae", "P. ovale", "P. vivax" and "P. knowlesi". Among those infected, "P. falciparum" is the most common species identified (~75%) followed by "P. vivax" (~20%). Although "P. falciparum" traditionally accounts for the majority of deaths, recent evidence suggests that "P. vivax" malaria is associated with potentially life-threatening conditions about as often as with a diagnosis of "P. falciparum" infection. "P. vivax " proportionally is more common outside Africa. There have been documented human infections with several species of "Plasmodium" from higher apes; however, except for "P. knowlesi"—a zoonotic species that causes malaria in macaques—these are mostly of limited public health importance.

Global warming is likely to affect malaria transmission, but the severity and geographic distribution of such effects is uncertain.

More than 300 million people worldwide have asthma. The rate of asthma increases as countries become more urbanized and in many parts of the world those who develop asthma do not have access to medication and medical care. Within the United States, African Americans and Latinos are four times more likely to suffer from severe asthma than whites. The disease is closely tied to poverty and poor living conditions. Asthma is also prevalent in children in low income countries. Homes with roaches and mice, as well as mold and mildew put children at risk for developing asthma as well as exposure to cigarette smoke.

Unlike many other Western countries, the mortality rate for asthma has steadily risen in the United States over the last two decades. Mortality rates for African American children due to asthma are also far higher than that of other racial groups. For African Americans, the rate of visits to the emergency room is 330 percent higher than their white counterparts. The hospitalization rate is 220 percent higher and the death rate is 190 percent higher. Among Hispanics, Puerto Ricans are disporpotionatly affected by asthma with a disease rate that is 113 percent higher than non-Hispanic Whites and 50 percent higher than non-Hispanic Blacks. Studies have shown that asthma morbidity and mortality are concentrated in inner city neighborhoods characterized by poverty and large minority populations and this affects both genders at all ages. Asthma continues to have an adverse effects on the health of the poor and school attendance rates among poor children. 10.5 million days of school are missed each year due to asthma.

AIDS is a disease of the human immune system caused by the human immunodeficiency virus (HIV). Primary modes of HIV transmission in sub-Saharan Africa are sexual intercourse, mother-to-child transmission (vertical transmission), and through HIV-infected blood. Since rate of HIV transmission via heterosexual intercourse is so low, it is insufficient to cause AIDS disparities between countries. Critics of AIDS policies promoting safe sexual behaviors believe that these policies miss the biological mechanisms and social risk factors that contribute to the high HIV rates in poorer countries. In these developing countries, especially those in sub-Saharan Africa, certain health factors predispose the population to HIV infections.

Many of the countries in Sub-Saharan Africa are ravaged with poverty and many people live on less than one United States dollar a day. The poverty in these countries gives rise to many other factors that explain the high prevalence of AIDS. The poorest people in most African countries suffer from malnutrition, lack of access to clean water, and have improper sanitation. Because of a lack of clean water many people are plagued by intestinal parasites that significantly increase their chances of contracting HIV due to compromised immune system. Malaria, a disease still rampant in Africa also increases the risk of contracting HIV. These parasitic diseases, affect the body’s immune response to HIV, making people more susceptible to contracting the disease once exposed. Genital schistosomiasis, also prevalent in the topical areas of Sub-Saharan Africa and many countries worldwide, produces genital lesions and attract CD4 cells to the genital region which promotes HIV infection. All these factors contribute to the high rate of HIV in Sub-Saharan Africa. Many of the factors seen in Africa are also present in Latin America and the Caribbean and contribute to the high rates of infections seen in those regions. In the United States, poverty is a contributing factor to HIV infections. There is also a large racial disparity, with African Americans having a significantly higher rate of infection than their white counterparts.

More than 90% of the global burden of visceral leishmaniasis (VL) is contributed by six countries: Bangladesh, Brazil, Ethiopia, India, South Sudan and Sudan. In India, more than 70% VL cases are reported from the state of Bihar. North Bihar, India (including Araria, Purnea, and Kishanganj) is the endemic zone of this disease.The disease is endemic in Iran including Ardabil, Fars, North Khorasan...

But, while the disease's geographical range is broad, it is not continuous. The disease clusters around areas of drought, famine, and high population density. In Africa, this has meant a knot of infection centers mostly in Sudan, Kenya, and Somalia. Living conditions here have changed very little in the past century, and the people are not normally very mobile. Parts of the Sudan, in particular the Upper Nile region, are almost totally cut off from the rest of the country, and most people tend to remain at their place of birth.

There are no vaccines or preventive drugs for visceral leishmaniasis. The most effective method to prevent infection is to protect from sand fly bites. To decrease the risk of being bitten, these precautionary measures are suggested:

- Outdoors:

1. Avoid outdoor activities, especially from dusk to dawn, when sand flies generally are the most active.

2. When outdoors (or in unprotected quarters), minimize the amount of exposed (uncovered) skin to the extent that is tolerable in the climate. Wear long-sleeved shirts, long pants, and socks; and tuck your shirt into your pants.

3. Apply insect repellent to exposed skin and under the ends of sleeves and pant legs. Follow the instructions on the label of the repellent. The most effective repellents generally are those that contain the chemical DEET (N,N-diethylmetatoluamide).

- Indoors:

1. Stay in well-screened or air-conditioned areas.

2. Keep in mind that sand flies are much smaller than mosquitoes and therefore can get through smaller holes.

3. Spray living/sleeping areas with an insecticide to kill insects.

4. If you are not sleeping in a well-screened or air-conditioned area, use a bed net and tuck it under your mattress. If possible, use a bed net that has been soaked in or sprayed with a pyrethroid-containing insecticide. The same treatment can be applied to screens, curtains, sheets, and clothing (clothing should be retreated after five washings)."

On February 2012, the nonprofit Infectious Disease Research Institute launched a clinical trial of the visceral leishmaniasis vaccine. The vaccine is a recombinant form of two fused Leishmania parasite proteins with an adjuvant. Two phase 1 clinical trials with healthy volunteers are to be conducted. The first one takes place in Washington (state) and is followed by a trial in India.

There is some debate among the WHO, CDC, and infectious disease experts over which diseases are classified as neglected tropical diseases. Feasey, a researcher in neglected tropical diseases, notes 13 neglected tropical diseases: ascariasis, Buruli ulcer, Chagas disease, dracunculiasis, hookworm infection, human African trypanosomiasis, Leishmaniasis, leprosy, lymphatic filariasis, onchocerciasis, schistosomiasis, trachoma, and trichuriasis. Fenwick recognizes 12 "core" neglected tropical diseases: ascariasis, Buruli ulcer, Chagas disease, dracunculiasis, human African trypanosomiasis, Leishmaniasis, leprosy, lymphatic filariasis, onchocerciasis, schistosomiasis, trachoma, and trichuriasis.

These diseases result from four different classes of causative pathogens: (i) protozoa (for Chagas disease, human African trypanosomiasis, leishmaniases); (ii) bacteria (for Buruli ulcer, leprosy, trachoma, yaws), (iii) helminths or metazoan worms (for cysticercosis/taeniasis, dracunculiasis, echinococcosis, foodborne trematodiases, lymphatic filariasis, onchocerciasis, schistosomiasis, soil-transmitted helminthiasis); and (iv) viruses (dengue and chikungunya, rabies).

The World Health Organization recognizes the seventeen diseases below as neglected tropical diseases.

Globally, an estimated 125 million or more pregnant women per year risk contracting PAM. Pregnancy-related malaria causes around 100,000 infant deaths each year, due in large part to low birth weight.

Deworming treatments in infected children may have some nutritional benefit, as worms are often partially responsible for malnutrition. However, in areas where these infections are common, there is strong evidence that mass deworming campaigns do not have a positive effect on children's average nutritional status, levels of blood haemoglobin, cognitive abilities, performance at school or survival. To achieve health gains in the longer term, improvements in sanitation and hygiene behaviours are also required, together with deworming treatments.

The disease is found in tropical countries in Africa, the Caribbean, eastern South America, Southeast Asia, and the Middle East. "S. mansoni" is found in parts of South America and the Caribbean, Africa, and the Middle East; "S. haematobium" in Africa and the Middle East; and "S. japonicum" in the Far East. "S. mekongi" and "S. intercalatum" are found locally in Southeast Asia and central West Africa, respectively.

The disease is endemic in about 75 developing countries and mainly affects people living in rural agricultural and peri-urban areas.

Estimates regarding the number of deaths vary. Worldwide, the Global Burden of Disease Study issued in 2010 estimated 12,000 direct deaths while the WHO in 2014 estimated more than 200,000 annual deaths related to schistosomiasis. Another 20 million have severe consequences from the disease. It is the most deadly of the neglected tropical diseases.

Mosquito-borne diseases, such as dengue fever and malaria, typically affect third world countries and areas with tropical climates. Mosquito vectors are sensitive to climate changes and tend to follow seasonal patterns. Between years there are often dramatic shifts in incidence rates. The occurrence of this phenomenon in endemic areas makes mosquito-borne viruses difficult to treat.

Dengue fever is caused by infection through viruses of the family Flaviviridae. The illness is most commonly transmitted by Aedes aegypti mosquitoes in tropical and subtropical regions. Dengue virus has four different serotypes, each of which are antigenically related but have limited cross-immunity to reinfection.

Although dengue fever has a global incidence of 50-100 million cases, only several hundreds of thousands of these cases are life-threatening. The geographic prevalence of the disease can be examined by the spread of the Aedes aegypti. Over the last twenty years, there has been a geographic spread of the disease. Dengue incidence rates have risen sharply within urban areas which have recently become endemic hot spots for the disease. The recent spread of Dengue can also be attributed to rapid population growth, increased coagulation in urban areas, and global travel. Without sufficient vector control, the dengue virus has evolved rapidly over time, posing challenges to both government and public health officials.

Malaria is caused by a protozoan called Plasmodium falciparum. P. falciparum parasites are transmitted mainly by the Anopheles gambiae complex in rural Africa. In just this area, P. falciparum infections comprise an estimated 200 million clinical cases and 1 million annual deaths. 75% of individuals afflicted in this region are children. As with dengue, changing environmental conditions have led to novel disease characteristics. Due to increased illness severity, treatment complications, and mortality rates, many public health officials concede that malaria patterns are rapidly transforming in Africa. Scarcity of health services, rising instances of drug resistance, and changing vector migration patterns are factors that public health officials believe contribute to malaria’s dissemination.

Climate heavily affects mosquito vectors of malaria and dengue. Climate patterns influence the lifespan of mosquitos as well as the rate and frequency of reproduction. Climate change impacts have been of great interest to those studying these diseases and their vectors. Additionally, climate impacts mosquito blood feeding patterns as well as extrinsic incubation periods. Climate consistency gives researchers an ability to accurately predict annual cycling of the disease but recent climate unpredictability has eroded researchers’ ability to track the disease with such precision.

The arboviruses have expanded their geographic range and infected populations that had no recent community knowledge of the diseases carried by the "Aedes aegypti" mosquito. Education and community awareness campaigns are necessary for prevention to be effective. Communities are educated on how the disease is spread, how they can protect themselves from infection and the symptoms of infection. Community health education programs can identify and address the social/economic and cultural issues that can hinder preventative measures. Community outreach and education programs can identify which preventative measures a community is most likely to employ. Leading to a targeted prevention method that has a higher chance of success in that particular community. Community outreach and education includes engaging community health workers and local healthcare providers, local schools and community organizations to educate the public on mosquito vector control and disease prevention.

The disease results from the aggregation of erythrocytes infected by "Plasmodium falciparum" which have been shown to adhere to chondroitin sulfate A (CSA) on placental proteoglycans causing them to accumulate in the intervillous spaces of the placenta, blocking the crucial flow of nutrients from mother to embryo.

Some of the strategies for controlling tropical diseases include:

- Draining wetlands to reduce populations of insects and other vectors, or introducing natural predators of the vectors.

- The application of insecticides and/or insect repellents) to strategic surfaces such as clothing, skin, buildings, insect habitats, and bed nets.

- The use of a mosquito net over a bed (also known as a "bed net") to reduce nighttime transmission, since certain species of tropical mosquitoes feed mainly at night.

- Use of water wells, and/or water filtration, water filters, or water treatment with water tablets to produce drinking water free of parasites.

- Sanitation to prevent transmission through human waste.

- In situations where vectors (such as mosquitoes) have become more numerous as a result of human activity, a careful investigation can provide clues: for example, open dumps can contain stagnant water that encourage disease vectors to breed. Eliminating these dumps can address the problem. An education campaign can yield significant benefits at low cost.

- Development and use of vaccines to promote disease immunity.

- Pharmacologic pre-exposure prophylaxis (to prevent disease before exposure to the environment and/or vector).

- Pharmacologic post-exposure prophylaxis (to prevent disease after exposure to the environment and/or vector).

- Pharmacologic treatment (to treat disease after infection or infestation).

- Assisting with economic development in endemic regions. For example, by providing microloans to enable investments in more efficient and productive agriculture. This in turn can help subsistence farming to become more profitable, and these profits can be used by local populations for disease prevention and treatment, with the added benefit of reducing the poverty rate.

- Hospital for Tropical Diseases

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- List of epidemics

- Waterborne diseases

- Globalization and disease

Additional neglected tropical diseases include:

Some tropical diseases are very rare, but may occur in sudden epidemics, such as the Ebola hemorrhagic fever, Lassa fever and the Marburg virus. There are hundreds of different tropical diseases which are less known or rarer, but that, nonetheless, have importance for public health.

It is estimated that intestinal nematode infections cause 5 million disability-adjusted life years (DALYS) to be lost, of which hookworm infections account for more than 3 million DALYS and ascaris infections more than 1 million. There are also signs of progress: The Global Burden of Disease Study published in 2015 estimates a 46 percent (59 percent when age standardised) reduction in years lived with disability (YLD) for the 13-year time period from 1990 to 2013 for all intestinal/nematode infections, and even a 74 percent (80 percent when age standardised) reduction in YLD from ascariasis.

Even in areas of high prevalence, the frequency and severity of infection is not uniform within communities or families. A small proportion of community members harbour the majority of worms, and this depends on age. The maximum worm burden is at five to ten years of age, declining rapidly thereafter. Individual predisposition to helminthiasis for people with the same sanitation infrastructure and hygiene behavior is thought to result from differing immunocompetence, nutritional status, and genetic factors. Because individuals are predisposed to a high or a low worm burden, the burden reacquired after successful treatment is proportional to that before treatment.

Tropical and sub-tropical regions are the main areas affected by nematodes and parasitic worms, which often causes filariasis. Around 20% of immigrants to Spain are children from these regions. There are concerns about absolute eosinophilia in immigrants that is correlated with parasitic diseases that may go undiagnosed. Absolute eosinophilia is clinically diagnosed as >0.45×10 eosinophilic leucocytes/L of peripheral blood. Recent studies suggest that around 60% of children with relative eosinophilia contracted this via parasitic infections. Relative eosinophilia is different from absolute because relative refers to an increase in percentage of white blood cells (i.e. leukocytes) due to a loss of blood plasma; where as absolute eosinophilia is purely an increase in white blood cell production. Of those with relative eosinophilia, 40% were undiagnosed until these studies. Therefore, there is a great need for thorough parasitological studies in this area of tropical infectious diseases.

Acanthocheilonemiasis is caused by the parasite, "mansonella perstans." "M. perstans" is primarily found in central Africa and in some areas of South America, therefore the most affected populations are located in these areas. Acanthocheilonemiasis affects humans in these areas in equal numbers. The prevalence of this condition does significantly increase with age. Furthermore, the parasite is most commonly found in areas of tropical forests with alternating swamps and open ground.

Approximately 114 million people in Africa are infected with "M. perstans", including 33 sub-Saharan African countries. Recent studies focused on Gabon specifically, where febrile and tropical diseases are common. Contrary to popular recent suggestions, "M. perstans" does not influence the emergence of febrile diseases, including HIV, tuberculosis, bacteremia, and malaria. In general, hemoglobin levels in individuals with malaria are severely reduced from that of a healthy individual. Reduced levels occur because the malaria parasite, "Plasmodium falciparum," utilizes human hemoglobin as its major energy source. Filariasis, in combination with severe malaria, actually shows higher hemoglobin levels than in severe malaria alone. In addition, "M. perstans" did not have adverse effects on those with HIV, as there were actually higher levels of CD4 in HIV patients co-infected with "M. perstans". Further research in this area may allude to clinical manifestations of this infectious disease, as there could be possible benefits by contracting "M. perstans".

The cause of hemolytic crises in this disease is unknown (mainly due to intravascular haemolysis). There is rapid and massive destruction of red blood cells resulting in hemoglobinemia (hemoglobin in the blood, but outside the red blood cells), hemoglobinuria (hemoglobin in urine), intense jaundice, anuria (passing less than 50 milliliters of urine in a day), and finally death in the majority of cases.

The most probable explanation for blackwater fever is an autoimmune reaction apparently caused by the interaction of the malaria parasite and the use of quinine. Blackwater fever is caused by heavy parasitization of red blood cells with "Plasmodium falciparum". There has been at least one case, however, attributed to "Plasmodium vivax".

Blackwater fever is a serious complication of malaria, but cerebral malaria has a higher mortality rate. Blackwater fever is much less common today than it was before 1950. It may be that quinine plays a role in triggering the condition, and this drug is no longer commonly used for malaria prophylaxis. Quinine remains important for treatment of malaria.