Owing to the non-specific nature of the presentation of symptoms, diagnosis of malaria in non-endemic areas requires a high degree of suspicion, which might be elicited by any of the following: recent travel history, enlarged spleen, fever, low number of platelets in the blood, and higher-than-normal levels of bilirubin in the blood combined with a normal level of white blood cells. Reports in 2016 and 2017 from countries were malaria is common suggest high levels of over diagnosis due to insufficient or inaccurate laboratory testing.

Malaria is usually confirmed by the microscopic examination of blood films or by antigen-based rapid diagnostic tests (RDT). In some areas, RDTs need to be able to distinguish whether the malaria symptoms are caused by "Plasmodium falciparum" or by other species of parasites since treatment strategies could differ for non-"P. falciparum" infections. Microscopy is the most commonly used method to detect the malarial parasite—about 165 million blood films were examined for malaria in 2010. Despite its widespread usage, diagnosis by microscopy suffers from two main drawbacks: many settings (especially rural) are not equipped to perform the test, and the accuracy of the results depends on both the skill of the person examining the blood film and the levels of the parasite in the blood. The sensitivity of blood films ranges from 75–90% in optimum conditions, to as low as 50%. Commercially available RDTs are often more accurate than blood films at predicting the presence of malaria parasites, but they are widely variable in diagnostic sensitivity and specificity depending on manufacturer, and are unable to tell how many parasites are present.

In regions where laboratory tests are readily available, malaria should be suspected, and tested for, in any unwell person who has been in an area where malaria is endemic. In areas that cannot afford laboratory diagnostic tests, it has become common to use only a history of fever as the indication to treat for malaria—thus the common teaching "fever equals malaria unless proven otherwise". A drawback of this practice is overdiagnosis of malaria and mismanagement of non-malarial fever, which wastes limited resources, erodes confidence in the health care system, and contributes to drug resistance. Although polymerase chain reaction-based tests have been developed, they are not widely used in areas where malaria is common as of 2012, due to their complexity.

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.

A Zika virus infection might be suspected if symptoms are present and an individual has traveled to an area with known Zika virus transmission. Zika virus can only be confirmed by a laboratory test of body fluids, such as urine or saliva, or by blood test.

Laboratory blood tests can identify evidence of chikungunya or other similar viruses such as dengue and Zika. Blood test may confirm the presence of IgM and IgG anti-chikungunya antibodies. IgM antibodies are highest 3 to 5 weeks after the beginning of symptoms and will continue be present for about 2 months.

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.

Generally speaking, acanthocheilonemiasis does not show initial symptoms. However, if symptoms do arise, it is typically in individuals who are visiting highly infected areas rather than natives to those areas. A major common laboratory finding is an increase in specialized white blood cells, which is called eosinophilia.

Other symptoms include itchy skin, neurological symptoms, abdominal and chest pain, muscle pain, and swelling underneath the skin. If there are abnormally high levels of white blood cells, then a physical examination will most likely find an enlarged spleen or liver.

In certain scenarios, nematodes may physically lodge into the chest or abdomen, resulting in an inflammation. Diagnosis of this condition usually occurs via a blood smear examination under light microscopy.

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.

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.

Though heart disease is not exclusive to the poor, there are aspects of a life of poverty that contribute to its development. This category includes coronary heart disease, stroke and heart attack. Heart disease is the leading cause of death worldwide and there are disparities of morbidity between the rich and poor. Studies from around the world link heart disease to poverty. Low neighborhood income and education were associated with higher risk factors. Poor diet, lack of exercise and limited (or no) access to a specialist were all factors related to poverty, though to contribute to heart disease.

Both low income and low education were predictors of coronary heart disease, a subset of cardiovascular disease. Of those admitted to hospital in the United States for heart failure, women and African Americans were more likely to reside in lower income neighborhoods. In the developing world, there is a 10 fold increase in cardiac events in the black and urban populations.

Biotechnology companies in the developing world have targeted neglected tropical diseases due to need to improve global health.

Mass drug administration is considered a possible method for eradication, especially for lymphatic filariasis, onchocerciasis, and trachoma, although drug resistance is a potential problem. According to Fenwick, Pfizer donated 70 million doses of drugs in 2011 to eliminate trachoma through the International Trachoma Initiative. Merck has helped The African Programme for the Control of Onchocerciasis (APOC) and Oncho Elimination Programme for the Americas to greatly diminished the effect of Onchocerciasis by donating ivermectin. Merck KGaA pledged to give 200 million tablets of praziquantel over 10 years, the only cure for schistosomiasis. GlaxoSmithKline has donated two billion tablets of medicine for lymphatic filariasis and pledged 400 million deworming tablets per year for five years in 2010. Johnson & Johnson has pledged 200 million deworming tablets per year. Novartis has pledged leprosy treatment, EISAI pledged two billion tablets to help treat lymphatic filariasis.

There are currently only two donor-funded non-governmental organizations that focus exclusively on NTDs: the Schistosomiasis Control Initiative and Deworm the World. Despite under-funding, many neglected diseases are cost-effective to treat and prevent. The cost of treating a child for infection of soil transmitted helminths and schistosomes (some of the main causes of neglected diseases), is less than US$0.50 per year, when administered as part of school-based mass deworming by Deworm the World. This programme is recommended by Giving What We Can and the Copenhagen Consensus Centre as one of the most efficient and cost-effective solutions. The efforts of Schistosomiasis Control Initiative to combat neglected diseases include the use of rapid-impact packages: supplying schools with packages including four or five drugs, and training teachers in how to administer them.

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.

Evaluation of numerous public health interventions has generally shown that improvement in each individual component ordinarily attributed to poverty (for example, sanitation, health education and underlying nutrition status) often have minimal impact on transmission. For example, one study found that the introduction of latrines into a resource-limited community only reduced the prevalence of hookworm infection by four percent. However, another study in Salvador, Brazil found that improved drainage and sewerage had a significant impact (p<0.0001) on the prevalence of hookworm infection but no impact at all on the intensity of hookworm infection. This seems to suggest that environmental control alone has a limited but incomplete effect on the transmission of hookworms. It is imperative, therefore, that more research is performed to understand the efficacy and sustainability of integrated programs that combine numerous preventive methods including education, sanitation, and treatment.

Neonatal sepsis of the newborn is an infection that has spread through the entire body. The inflammatory response to this systematic infection can be as serious as the infection itself. In infants that weigh under 1500 g, sepsis is the most common cause of death. Three to four percent of infants per 1000 births contract sepsis. The mortality rate from sepsis is near 25%. Infected sepsis in an infant can be identified by culturing the blood and spinal fluid and if suspected, intravenous antibiotics are usually started. Lumbar puncture is controversial because in some cases it has found not to be necessary while concurrently, without it estimates of missing up to one third of infants with meningitis is predicted.

Only specialized laboratories can adequately diagnose "Babesia" infection in humans, so "Babesia" infections are considered highly under-reported. It develops in patients who live in or travel to an endemic area or receive a contaminated blood transfusion within the preceding 9 weeks, so this aspect of the medical history is vital. Babesiosis may be suspected when a person with such an exposure history develops persistent fevers and hemolytic anemia. The definitive diagnostic test is the identification of parasites on a Giemsa-stained thin-film blood smear.

So-called "Maltese cross formations" on the blood film are diagnostic (pathognomonic) of babesiosis, since they are not seen in malaria, the primary differential diagnosis. Careful examination of multiple smears may be necessary, since "Babesia" may infect less than 1% of circulating red blood cells, thus be easily overlooked.

Serologic testing for antibodies against "Babesia" (both IgG and IgM) can detect low-level infection in cases with a high clinical suspicion, but negative blood film examinations. Serology is also useful for differentiating babesiosis from malaria in cases where people are at risk for both infections. Since detectable antibody responses require about a week after infection to develop, serologic testing may be falsely negative early in the disease course.

A polymerase chain reaction (PCR) test has been developed for the detection of "Babesia" from the peripheral blood. PCR may be at least as sensitive and specific as blood-film examination in diagnosing babesiosis, though it is also significantly more expensive. Most often, PCR testing is used in conjunction with blood film examination and possibly serologic testing.

Other laboratory findings include decreased numbers of red blood cells and platelets on complete blood count.

In animals, babesiosis is suspected by observation of clinical signs (hemoglobinuria and anemia) in animals in endemic areas. Diagnosis is confirmed by observation of merozoites on thin film blood smear examined at maximum magnification under oil using Romonovski stains (methylene blue and eosin). This is a routine part of the veterinary examination of dogs and ruminants in regions where babesiosis is endemic.

"Babesia canis" and "B. bigemina" are "large "Babesia" species" that form paired merozoites in the erythrocytes, commonly described as resembling "two pears hanging together", rather than the "Maltese cross" of the "small "Babesia" species". Their merozoites are around twice the size of small ones.

Cerebral babesiosis is suspected "in vivo" when neurological signs (often severe) are seen in cattle that are positive for "B. bovis" on blood smear, but this has yet to be proven scientifically. Outspoken red discoloration of the grey matter "post mortem" further strengthens suspicion of cerebral babesiosis. Diagnosis is confirmed "post mortem" by observation of "Babesia"-infected erythrocytes sludged in the cerebral cortical capillaries in a brain smear.

Diagnosis depends on finding characteristic worm eggs on microscopic examination of the stools, although this is not possible in early infection. Early signs of infection in most dogs include limbular limping and anal itching. The eggs are oval or elliptical, measuring 60 µm by 40 µm, colorless, not bile stained and with a thin transparent hyaline shell membrane. When released by the worm in the intestine, the egg contains an unsegmented ovum. During its passage down the intestine, the ovum develops and thus the eggs passed in feces have a segmented ovum, usually with 4 to 8 blastomeres.

As the eggs of both "Ancylostoma" and "Necator" (and most other hookworm species) are indistinguishable, to identify the genus, they must be cultured in the lab to allow larvae to hatch out. If the fecal sample is left for a day or more under tropical conditions, the larvae will have hatched out, so eggs might no longer be evident. In such a case, it is essential to distinguish hookworms from "Strongyloides" larvae, as infection with the latter has more serious implications and requires different management. The larvae of the two hookworm species can also be distinguished microscopically, although this would not be done routinely, but usually for research purposes. Adult worms are rarely seen (except via endoscopy, surgery or autopsy), but if found, would allow definitive identification of the species. Classification can be performed based on the length of the buccal cavity, the space between the oral opening and the esophagus: hookworm rhabditoform larvae have long buccal cavities whereas "Strongyloides" rhabditoform larvae have short buccal cavities.

Recent research has focused on the development of DNA-based tools for diagnosis of infection, specific identification of hookworm, and analysis of genetic variability within hookworm populations. Because hookworm eggs are often indistinguishable from other parasitic eggs, PCR assays could serve as a molecular approach for accurate diagnosis of hookworm in the feces.

Specific helminths can be identified through microscopic examination of their eggs (ova) found in faecal samples. The number of eggs is measured in units of eggs per gram. However, it does not quantify mixed infections, and in practice, is inaccurate for quantifying the eggs of schistosomes and soil-transmitted helmiths. Sophisticated tests such as serological assays, antigen tests, and molecular diagnosis are also available; however, they are time-consuming, expensive and not always reliable.

For basic diagnosis, specific helminths can be generally identified from the faeces, and their eggs microscopically examined and enumerated using fecal egg count method. However, there are certain limitations such as the inability to identify mixed infections, and on clinical practice, the technique is inaccurate and unreliable.

A novel effective method for egg analysis is the Kato-Katz technique. It is a highly accurate and rapid method for "A. lumbricoides" and "T. trichiura"; however not so much for hookworm, which could be due to fast degeneration of the rather delicate hookworm eggs.

Biopsies or cultures of a person's tick wound (eschar) are used to diagnose ATBF. However, this requires special culture media and can only be done by a laboratory with biohazard protection. There are more specialized laboratory tests available that use quantitative polymerase chain reactions (qPCR), but can only be done by laboratories with special equipment. Immunofluorescence assays can also be used, but are hard to interpret because of cross-reactions with other rickettsiae bacteria.

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

- Tropical medicine

- Infectious disease

- Neglected diseases

- List of epidemics

- Waterborne diseases

- Globalization and disease

Symptoms and the isolation of the virus pathogen the upper respiratory tract is diagnostic. Virus identification is specific immunologic methods and PCR. The presence of the virus can be rapidly confirmed by the detection of the virus antigen. The methods and materials used for identifying the RSV virus has a specificity and sensitivity approaching 85% to 95%. Not all studies confirm this sensitivity. Antigen detection has comparatively lower sensitivity rates that approach 65% to 75%.

Yellow fever is most frequently a clinical diagnosis, made on the basis of symptoms and the diseased person's whereabouts prior to becoming ill. Mild courses of the disease can only be confirmed virologically. Since mild courses of yellow fever can also contribute significantly to regional outbreaks, every suspected case of yellow fever (involving symptoms of fever, pain, nausea and vomiting six to 10 days after leaving the affected area) is treated seriously.

If yellow fever is suspected, the virus cannot be confirmed until six to 10 days after the illness. A direct confirmation can be obtained by reverse transcription polymerase chain reaction where the genome of the virus is amplified. Another direct approach is the isolation of the virus and its growth in cell culture using blood plasma; this can take one to four weeks.

Serologically, an enzyme linked immunosorbent assay during the acute phase of the disease using specific IgM against yellow fever or an increase in specific IgG-titer (compared to an earlier sample) can confirm yellow fever. Together with clinical symptoms, the detection of IgM or a fourfold increase in IgG-titer is considered sufficient indication for yellow fever. Since these tests can cross-react with other flaviviruses, like dengue virus, these indirect methods cannot conclusively prove yellow fever infection.

Liver biopsy can verify inflammation and necrosis of hepatocytes and detect viral antigens. Because of the bleeding tendency of yellow fever patients, a biopsy is only advisable "post mortem" to confirm the cause of death.

In a differential diagnosis, infections with yellow fever must be distinguished from other feverish illnesses like malaria. Other viral hemorrhagic fevers, such as Ebola virus, Lassa virus, Marburg virus, and Junin virus, must be excluded as cause.

Diagnosis of ATBF is mostly based on symptoms, as many laboratory tests are not specific for ATBF. Common laboratory test signs of ATBF are a low white blood cell count (lymphopenia) and low platelet count (thrombocytopenia), a high C-reactive protein, and mildly high liver function tests.

A stool ova and parasites exam reveals the presence of typical whipworm eggs. Typically, the Kato-Katz thick-smear technique is used for identification of the "Trichuris trichiura" eggs in the stool sample.

Although colonoscopy is not typically used for diagnosis, as the adult worms can be overlooked, especially with imperfect colon, there have been reported cases in which colonoscopy has revealed adult worms. Colonoscopy can directly diagnose trichuriasis by identification of the threadlike form of worms with an attenuated, whip-like end. Colonoscopy has been shown to be a useful diagnostic tool, especially in patients infected with only a few male worms and with no eggs presenting in the stool sample.

Trichuriasis can be diagnosed when "T. trichiura" eggs are detected in stool examination. Eggs will appear barrel-shaped and unembryonated, having bipolar plugs and a smooth shell. Rectal prolapse can be diagnosed easily using defecating proctogram and is one of many methods for imaging the parasitic infection. Sigmoidoscopys show characteristic white bodies of adult worms hanging from inflamed mucosa ("coconut cake rectum").

Vaccination is recommended for those traveling to affected areas, because non-native people tend to develop more severe illness when infected. Protection begins by the 10th day after vaccine administration in 95% of people, and had been reported to last for at least 10 years. WHO now states that a single dose of vaccination is sufficient to confer lifelong immunity against yellow fever disease." The attenuated live vaccine stem 17D was developed in 1937 by Max Theiler. The World Health Organization (WHO) recommends routine vaccinations for people living in affected areas between the 9th and 12th month after birth.

Up to one in four people experience fever, aches, and local soreness and redness at the site of injection. In rare cases (less than one in 200,000 to 300,000), the vaccination can cause yellow fever vaccine–associated viscerotropic disease, which is fatal in 60% of cases. It is probably due to the genetic morphology of the immune system. Another possible side effect is an infection of the nervous system, which occurs in one in 200,000 to 300,000 cases, causing yellow fever vaccine-associated neurotropic disease, which can lead to meningoencephalitis and is fatal in less than 5% of cases.

The Yellow Fever Initiative, launched by WHO in 2006, vaccinated more than 105 million people in 14 countries in West Africa. No outbreaks were reported during 2015. The campaign was supported by the GAVI Alliance, and governmental organizations in Europe and Africa. According to the WHO, mass vaccination cannot eliminate yellow fever because of the vast number of infected mosquitoes in urban areas of the target countries, but it will significantly reduce the number of people infected.

In March 2017, WHO launched a vaccination campaign in Brazil with 3.5 million doses from an emergency stockpile. In March 2017 the WHO recommended vaccination for travellers to certain parts of Brazil.