Proceedings of the Seventy-Ninth Annual Meeting of the New Jersey Mosquito Control Association, Inc. 1992, pp 115-122.
(Please use this citation when referring to this work)
WAYNE J. CRANS, Mosquito Research & Control, Department of Entomology, Cook College, Rutgers University, New Brunswick, NJ 08903
Introduction
Human malaria is a disease of tropical and subtropical areas of the world that is transmitted solely by mosquitoes in the genus Anopheles. The causal agent is a parasitic protozoan in the genus Plasmodium that destroys red blood cells during its asexual reproductive processes. Complications during the course of infection may include anemia, general malaise, liver disfunction and brain damage. Previously infected humans function as the only reservoirs of infection; thus, human carriers serve as the sole source for the +300 million infections that are reported each year.
Four different species of Plasmodium produce infections in humans: P. vivax (Tertian), P. ovale (Mid Tertian), P. falciparum (Malignant Tertian) and P. malariae (Quartan). Malaria infections are most common among impoverished groups of people that have repeated contact with high anopheline populations; however, human malaria can be sustained in any area where there are 1) human carriers, 2) a non-immune human population, 3) suitable Anopheles vectors and 4) temperatures above 60 degrees F.
In 1991, the public was shocked to learn that 2 cases of mosquito-borne P. vivax malaria were contracted in New Jersey during the month of August. In fact, the 4 necessary ingredients for malaria transmission are present every year with: 1) human carriers (visitors to malarious areas), 2) a non-immune human population (virtually everyone in the United States), 3) suitable Anopheles vectors (An. quadrimaculatus) and 4) temperatures above 60 degrees F (New Jersey summer season).
Malaria was a serious health issue in New Jersey until its eradication the 1950's. This paper gives a brief history of the events that took place in Jersey's battle against the disease and the individuals that were instrumental in the disease's elimination.
Malaria in New Jersey Prior to Organized Mosquito Control
Human malaria was apparently introduced to the new world because there is no evidence that the disease occurred in American Indian populations prior to the arrival of Columbus. The first documented account of the disease in the western hemisphere is found in the records of Sir Francis Drake who claimed to have lost 500 men to malaria during a Caribbean voyage in 1588. The disease gained a firm foothold in the North American continent during the 1600's and plagued the colonization of the new world as far north as Massachusetts. Malaria had its greatest impact in the more southern colonies where ambient temperatures permitted transmission to take place nearly every month of the year.
The earliest health statistics that are available from New Jersey attribute 481 deaths to malaria in 1881, emphasizing that the disease was firmly entrenched in the State prior to the turn of the century. The reliability of the statistics are somewhat questionable since P. vivax (the parasite responsible for most of the cases in temperate climates) rarely results in death. It is possible that the unusually high death rate was due to diseases other than malaria or to extenuating complications during the course of a typical infection. Diagnostic procedures were in their infancy at the time and the disease was still regarded as a mysterious malady that was vaguely tied to swampland habitat.
In 1888, federal funds became available for the organized study of insects in New Jersey and the Department of Entomology was created in the Agricultural Experiment Station at Rutgers College. Reverend George D. Hulst was named State Entomologist and functioned as the sole member of the Department of Entomology for one year. In 1889, John Bernhard Smith succeeded Dr. Hulst as entomologist at the Station. Because of his efforts in the study of mosquitoes, Dr. Smith would ultimately become known as the father of mosquito control and would play a vital role in the earliest efforts to eliminate malaria from New Jersey.
John B. Smith had a background in law with no formal training in science. He was, however, fascinated by insects and joined the Brooklyn Entomological Society shortly after he was admitted to the bar. Dr. Smith was a regular contributor to the Society's bulletin and ultimately became its editor. The exposure he gained from the publication led to a federal appointment in the U.S. Department of Agriculture conducting field work on economic pests. He was also given an assistant curator post in the Division of Insects at the United States National Museum and functioned in both posts until he accepted the position at the New Jersey Agricultural Experiment Station.
When John B. Smith came to New Jersey, he focused primarily on economic pests and made significant contributions in this regard. He established a nursery inspection system in the State to prevent the spread of infested plants and then used his law background to make nursery inspections mandatory. Similarly, he framed a plan for bee inspection and had the legislature enact that plan into law to combat foulbrood disease in the State. Dr. Smith conducted notable research on hundreds of agricultural insect pests during his tenure at the Experiment Station. It was not until 1901 that he shifted his attention to mosquitoes and began to formulate his concepts for mosquito control.
It was inevitable that Dr. Smith would eventually move from agricultural insect problems in New Jersey to the health problems posed by mosquitoes. Residents as well as visitors were sarcastically calling New Jersey the "Mosquito State" and even irresponsible politicians found it hard to deny the name. Droves of mosquitoes emanated from the meadow lands around Newark and much of southern New Jersey was uninhabitable because of mosquitoes. Health statistics showed that malaria was claiming lives and malaria was now known to be mosquito transmitted. Dr. Smith used his experience as a taxonomist and curator to systematically subdivide the mosquitoes that occurred in New Jersey and then focused on the biology of each in quest of a weak link in their life cycle that might be used to facilitate their control. He became the first entomologist to prove that salt marsh mosquitoes differed from rain barrel mosquitoes and that numerous other saltwater and freshwater pests were present in the state. Dr. Smith also demonstrated that mosquitoes bred solely in water and that drainage, grading and burying water holding receptacles could be used to reduce their numbers. Dr. Smith firmly believed that New Jersey's mosquitoes could be reduced to the point where they would be practically unnoticeable within a decade if the proper steps were taken.
Dr. Smith's solution, however, was controversial in political circles because he contended that mosquitoes were a state problem rather than a local problem. He realized that the mosquitoes that were biting the public in municipalities such as East Orange were being produced from the wetlands surrounding Newark and that no amount of local effort conducted within the individual municipalities would alleviate the problem. Similarly, he realized that much of the mosquito nuisance in southern New Jersey emanated from marshlands that did not fall under the jurisdiction of the municipalities that received the annoyance. Using his judicial background, he proposed a state law to mandate mosquito control. As might be expected, his proposal was met with ridicule by the legislators. The feeling at that time was that mosquitoes, mosquito nuisance and malaria were a fact of life in New Jersey. The concept of mandating mosquito control was as ludicrous as a law to control the weather.
John B. Smith, however, was a persistent man and proved his points by example. He contracted with local boards of health and outlined, in detail, the mosquito problems of each separate municipality from the urban centers around Newark to the farmlands along Delaware Bay. He pointed out the differences between coastal salt marsh mosquitoes and inland malaria-bearing mosquitoes and presented plans for their elimination. Pilot projects were enacted with local funding in key areas and legislators were encouraged to visit site locales where significant progress was being made in the elimination of nuisance species. His persistence and diplomacy (which was backed by good science) slowly made believers of the numerous skeptics that he faced in state government and the concept of a law to mandate mosquito control ceased to be a total joke among the legislators.
By 1911, Dr. Smith had convinced the State that mosquito control was plausible and that malaria cases could be reduced but poor health prohibited him from participating in the final stages of the battle he had initiated. In 1912, Governor Woodrow Wilson signed Chapter 104 of the New Jersey Health Codes into Law which 1) mandated mosquito control into law, 2) created the county mosquito commissions and 3) declared malaria a reportable disease. Ironically, Dr. Smith died 9 days before the document was signed into law.
Malaria During the Early Days of Organized Mosquito Control
Dr. Thomas J. Headlee succeeded Dr. Smith as State Entomologist in 1912 and moved forward with the work that had been initiated by his predecessor. Like John B. Smith, Dr. Headlee had an interest in economic entomology and guided the Department of Entomology in that area with his considerable expertise in agricultural pests. Dr. Headlee, however, had inherited the newly formed county mosquito extermination commissions that were mandated by law and immediately took steps to assure that the mandate was carried out. Dr. Headlee took the law seriously and ruled mosquito control with an iron hand. In 1914, the N.J. Mosquito Extermination Association was formed and Dr. Headlee installed himself as its permanent Secretary to assure that the goals of the association reflected the letter of the law. In 1921, Dr. Headlee created the organization known as the Associated Executives in Mosquito Control Work in New Jersey and became its permanent President to assure that the technical workers in mosquito control had frequent contact with the Experiment Station. Both organizations were designed to encourage interaction among mosquito control workers but both were also completely controlled by Dr. T. J. Headlee. In addition, Dr. Headlee had the power to approve or disapprove any county commission budget and used that power to keep the mosquito commissions subservient to the philosophies of the Experiment Station.
At the time the Mosquito Extermination Commissions were formed, malaria cases averaged about 500 per year in New Jersey, with about 14 deaths being attributed to the disease each year. There was, at the time, a very real concern to reduce the amount of malaria transmission now that mosquito control had been mandated into law. Loss of time to wage earners and a marked decrease in school attendance were just some of the reasons cited. The health statistics from 1914 revealed that malaria was not evenly distributed in the state (Table 1.) Five counties (Sussex, Mercer, Bergen, Essex & Union) were reporting nearly 90% of the cases and many counties with high mosquito populations did not have a malaria problem if the statistics were to be believed. The statistics created a controversy within the mosquito control community. One faction felt that malaria cases were being under-reported and that physicians were ignoring the new law that made malaria a reportable disease. Another faction felt that cases were being over-reported with physicians recording every undiagnosed malady as malaria.
Table 1. Malaria cases in New Jersey by county in 1914. (Modified from Hunt, 1915)
County: No. Cases Reported, No.Deaths
The accuracy of the health statistics of 1914 may be suspect but there is little doubt that malaria was entrenched within the State during that era. The town of Princeton in Mercer County was cited as an example. Princeton had a population of just over 5000 in 1914 but accounted for 100 of the 771 malaria cases that were reported in the state. One faction within the mosquito control community contended that none of the cases had been confirmed by a blood smear and that it was hard to believe that all were true malaria. The other faction pointed out the atrocious mosquito breeding conditions that could be seen by anyone traveling through that area on the Pennsylvania Railroad and wondered why nothing was being done to drain those swamps in view of the malaria reports. The anti-mosquito contingency outnumbered the anti-physician contingency within mosquito control, and under T. J. Headlee's guidance, mosquito control workers in New Jersey began to focus on elimination of Anopheles habitat to reduce the amount of malaria transmission in the state of New Jersey.
From 1915 to 1934, the newly formed mosquito control commissions in New Jersey focused on training their personnel in the recognition and elimination of anopheline habitat. By 1934, the annual case rate had dropped to about 10 and many New Jersey counties were declaring themselves malaria free. In 1935, however, an epidemic in Camden County brought things into perspective. Camden County had been malaria free for 20 years but 92 cases were confirmed in Pennsauken Township alone during the month of August. Mosquito surveillance revealed that Anopheles quadrimaculatus mosquitoes were breeding in the vicinity and immediate funding was given for drainage. The work was completed within the year and the case rate dropped from 92 in 1935 to only 2 in 1936.
Dr. Headlee retired from his position as Chair of the Department of Entomology in 1943 and was succeeded by Dr. Bailey B. Pepper. Like his predecessors, Dr. Pepper was an economic entomologist but understood New Jersey's mandate for mosquito control. Dr. Pepper also understood Dr. Headlee's methods of enforcing that mandate and quickly took steps to assure that the Experiment Station retained leadership in all aspects of state-wide mosquito control.
Malaria in New Jersey Following World War II
Malaria cases declined steadily in New Jersey until the war years when returning troops re-introduced P. vivax to many areas of the state. Table 2 lists the case rate during the war period and shows that New Jersey's malaria cases rose steadily in military personnel until they peaked in 1945 with 1,397 infections in military personnel and 1,412 total. The vast majority of the military cases were contracted abroad and most of the civilian cases were contracted out of state. The soaring case rate (coupled with relapses in many who had been cured) allowed local Anopheles to participate in limited indigenous transmission in some areas of the State. As a result, mosquito control was again urged to wage its own war on the mosquito vectors and minimize the number of cases acquired locally.
Table 2. Malaria in New Jersey during the war years. (Modified from Eakins, 1947 & 1951)
Year: Military Cases, CivilianCases; Total: Contracted in N. J.
1941: 0, 13; 13: 0
1942: 4, 16; 20: 7
1943: 16, 4; 20: 0
1944: 78 8, 38; 826: 5
1945: 1397, 15; 1412: 5
1946: 917, 14; 931: 5
1947: 49, 50; 99: 2
The influx of the thousands of military personnel that had been exposed to malaria in tropical areas and the likelihood that those cases might trigger indigenous transmission prompted the State Department of Health, the State Entomologist and the County Mosquito Extermination Commissions to evolve a plan for malaria control with the hope of eventual eradication. The plan was enacted in 1944 and became known as New Jersey's Cooperative Plan of Malaria Control.
The Cooperative Plan of Malaria Control requested local boards of health to 1) Notify the superintendent of the county mosquito commission of the location of each new case, 2) Visit the patient's home to secure a case history, and, 3) Examine the patient's home with a representative of the mosquito commission for the presence of mosquitoes and advice on the installation of screening which would prevent future mosquito entry. The county mosquito commission was asked to 1) Survey the vicinity for anopheline breeding places, and, 2) Institute proper control measures. The State Department of Health was expected to 1) Tabulate the corresponding paperwork, 2) Notify the State Entomologist, 3) Supply district health officers when needed, 4) Urge all physicians to cooperate fully, and, 5) Offer physicians the services of the state laboratory for blood examination. Rutgers University (in cooperation with the State Health Department) was asked to 1) Offer an evening lecture course in tropical diseases, and, 2) Offer a Saturday lecture and laboratory course in malaria parasitology.
The Cooperative Plan of Malaria Control worked well and health statistics from the late 1940's and early 1950's showed a steady decline in imported malaria and a complete cessation in natural transmission. The statistics suggest that malaria was eradicated from New Jersey by 1951 and New Jersey remained malaria free for 20 years. There is no evidence that any new cases were contracted via mosquito bite until the summer of 1991 when the necessary ingredients for transmission were met once again: 1) human carriers, 2) a non-immune human population, 3) suitable Anopheles vectors and 4) temperatures above 60 degrees F.
Considering the numbers of people that are traveling to malarious areas and being admitted back into the New York metropolitan area without blood screening, it is amazing that the disease has not been introduced repeatedly over the past 20 years. Some experts in the field feel that many of the cases reported as "Introduced Malaria" have, in fact, been contracted by An. quadrimaculatus that acquired gametocytes from a carrier that had visited a malarious area. Since there is no hard evidence to support that supposition, we must assume that the cases reported in 1991 were "unique".
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